WorldWideScience

Sample records for climate model simulations

  1. A Climate System Model, Numerical Simulation and Climate Predictability

    Institute of Scientific and Technical Information of China (English)

    ZENG Qingcun; WANG Huijun; LIN Zhaohui; ZHOU Guangqing; YU Yongqiang

    2007-01-01

    @@ The implementation of the project has lasted for more than 20 years. As a result, the following key innovative achievements have been obtained, ranging from the basic theory of climate dynamics, numerical model development and its related computational theory to the dynamical climate prediction using the climate system models:

  2. An Appraisal of Coupled Climate Model Simulations

    Energy Technology Data Exchange (ETDEWEB)

    Sperber, K; Gleckler, P; Covey, C; Taylor, K; Bader, D; Phillips, T; Fiorino, M; Achutarao, K

    2004-02-24

    In 2002, the Program for Climate Model Diagnosis and Intercomparison (PCMDI) proposed the concept for a state-of-the-science appraisal of climate models to be performed approximately every two years. Motivation for this idea arose from the perceived needs of the international modeling groups and the broader climate research community to document progress more frequently than provided by the Intergovernmental Panel on Climate Change (IPCC) Assessment Reports. A committee of external reviewers, which included senior researchers from four leading international modeling centers, supported the concept by stating in its review: ''The panel enthusiastically endorses the suggestion that PCMDI develop an independent appraisal of coupled model performance every 2-3 years. This would provide a useful 'mid-course' evaluation of modeling progress in the context of larger IPCC and national assessment activities, and should include both coupled and single-component model evaluations.''

  3. Climate system model, numerical simulation and climate predictability

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    @@ Thanks to its work of past more than 20 years,a research team led by Prof.ZENG Qingcun and Prof.WANG Huijun from the CAS Institute of Atmospheric Physics (IAP) has scored innovative achievements in their studies of basic theory of climate dynamics,numerical model development,its related computational theory,and the dynamical climate prediction using the climate system models.Their work received a second prize of the National Award for Natural Sciences in 2005.

  4. Regional climate simulations over Vietnam using the WRF model

    Science.gov (United States)

    Raghavan, S. V.; Vu, M. T.; Liong, S. Y.

    2016-10-01

    We present an analysis of the present-day (1961-1990) regional climate simulations over Vietnam. The regional climate model Weather Research and Forecasting (WRF) was driven by the global reanalysis ERA40. The performance of the regional climate model in simulating the observed climate is evaluated with a main focus on precipitation and temperature. The regional climate model was able to reproduce the observed spatial patterns of the climate, although with some biases. The model also performed better in reproducing the extreme precipitation and the interannual variability. Overall, the WRF model was able to simulate the main regional signatures of climate variables, seasonal cycles, and frequency distributions. This study is an evaluation of the present-day climate simulations of a regional climate model at a resolution of 25 km. Given that dynamical downscaling has become common for studying climate change and its impacts, the study highlights that much more improvements in modeling might be necessary to yield realistic simulations of climate at high resolutions before they can be used for impact studies at a local scale. The need for a dense network of observations is also realized as observations at high resolutions are needed when it comes to evaluations and validations of models at sub-regional and local scales.

  5. Evaluation of climate extremes in the CMIP5 model simulations

    Science.gov (United States)

    Sillmann, J.; Kharin, S.; Zhang, X.; Zwiers, F. W.

    2011-12-01

    Climate extremes manifest an important aspect of natural climate variability and anthropogenic climate change. To minimize human and financial losses caused by extreme events it is important to have reliable projections of their occurrence and intensity. State-of-the-art global climate models represented by the CMIP5 model ensemble are widely used as tools to simulate the present and project the future climate. Thus, it is crucial to get an understanding of how well climate extremes are simulated by these models in the present climate to be able to appraise their usefulness for future projections. We calculated a global set of well-defined indices for climate extremes based on daily temperature and precipitation data with the available CMIP5 models and use the indices to present a first-order evaluation of the model performance in comparison with re-analysis and a gridded observational dataset. We also focus our analysis on regional aspects of the model performance. Some of the indices are based on threshold exceedance, i.e. percentage of days below the 10th or above the 90th percentile of the maximum and minimum temperature. These indices require special attention for model evaluation as by definition the threshold exceedance is approximately 10% for individual models, re-analysis, and observations. We introduce a novel method to evaluate the model performance particular for these indices.

  6. A coupled climate model simulation of Marine Isotope Stage 3 stadial climate

    Directory of Open Access Journals (Sweden)

    J. Brandefelt

    2011-01-01

    Full Text Available We present a coupled global climate model (CGCM simulation, integrated for 1500 years to quasi-equilibrium, of a stadial (cold period within Marine Isotope Stage 3 (MIS 3. The simulated Greenland stadial 12 (GS12; ~44 ka BP annual global mean surface temperature (Ts is 5.5 °C higher than in the simulated recent past (RP climate and 1.3 °C lower than in the simulated Last Glacial Maximum (LGM; 21 ka BP climate. The simulated GS12 climate is evaluated against proxy data of sea surface temperature (SST. Simulated SSTs fall within the uncertainty range of the proxy SSTs for 30–50% of the sites depending on season. Proxy SSTs are higher than simulated SSTs in the Central North Atlantic, in contrast to earlier simulations of MIS 3 stadial climate in which proxy SSTs were found to be lower than simulated SST. The annual global mean Ts only changes by 0.10 °C from model years 500–599 to the last century of the simulation, indicating that the climate system may be close to equilibrium already after 500 years of integration. However, significant regional differences between the last century of the simulation and model years 500–599, with a maximum of 8 °C in temperature and 65% in precipitation in Southeastern Greenland in boreal winter, exist. Further, the agreement between simulated and proxy SST is improved from model years 500–599 to the last century of the simulation. El-Niño-Southern Oscillation (ENSO teleconnections in mean sea level pressure (MSLP are analysed for the last 300 years of the GS12, LGM and RP climate simulations. In agreement with an earlier study, we find that GS12 and LGM forcing and boundary conditions induce major modifications to ENSO teleconnections. However, significant differences in the teleconnection patterns are found between a 300-year time-slice starting after 195 model years and the last 300 years of the simulation. Thus we conclude that both the mean state and the

  7. Deficiencies in the simulation of the geographic distribution of climate types by global climate models

    Science.gov (United States)

    Zhang, Xianliang; Yan, Xiaodong

    2016-05-01

    The performances of General Circulation Models (GCMs) when checked with conventional methods (i.e. correlation, bias, root-mean-square error) can only be evaluated for each variable individually. The geographic distribution of climate type in GCM simulations, which reflects the spatial attributes of models and is related closely to the terrestrial biosphere, has not yet been evaluated. Thus, whether the geographic distribution of climate types was well simulated by GCMs was evaluated in this study for nine GCMs. The results showed that large areas of climate zones classified by the GCMs were allocated incorrectly when compared to the basic climate zones established by observed data. The percentages of wrong areas covered approximately 30-50 % of the total land area for most models. In addition, the temporal shift in the distribution of climate zones according to the GCMs was found to be inaccurate. Not only were the locations of shifts poorly simulated, but also the areas of shift in climate zones. Overall, the geographic distribution of climate types was not simulated well by the GCMs, nor was the temporal shift in the distribution of climate zones. Thus, a new method on how to evaluate the simulated distribution of climate types for GCMs was provided in this study.

  8. A coupled climate model simulation of Marine Isotope Stage 3 stadial climate

    Science.gov (United States)

    Brandefelt, J.; Kjellström, E.; Näslund, J.-O.; Strandberg, G.; Voelker, A. H. L.; Wohlfarth, B.

    2011-06-01

    We present a coupled global climate model (CGCM) simulation, integrated for 1500 yr to quasi-equilibrium, of a stadial (cold period) within Marine Isotope Stage 3 (MIS 3). The simulated Greenland stadial 12 (GS12; ~44 ka BP) annual global mean surface temperature (Ts) is 5.5 °C lower than in the simulated recent past (RP) climate and 1.3 °C higher than in the simulated Last Glacial Maximum (LGM; 21 ka BP) climate. The simulated GS12 is evaluated against proxy data and previous modelling studies of MIS3 stadial climate. We show that the simulated MIS 3 climate, and hence conclusions drawn regarding the dynamics of this climate, is highly model-dependent. The main findings are: (i) Proxy sea surface temperatures (SSTs) are higher than simulated SSTs in the central North Atlantic, in contrast to earlier simulations of MIS 3 stadial climate in which proxy SSTs were found to be lower than simulated SST. (ii) The Atlantic Meridional Overturning Circulation (AMOC) slows down by 50 % in the GS12 climate as compared to the RP climate. This slowdown is attained without freshwater forcing in the North Atlantic region, a method used in other studies to force an AMOC shutdown. (iii) El-Niño-Southern Oscillation (ENSO) teleconnections in mean sea level pressure (MSLP) are significantly modified by GS12 and LGM forcing and boundary conditions. (iv) Both the mean state and variability of the simulated GS12 is dependent on the equilibration. The annual global mean Ts only changes by 0.10 °C from model years 500-599 to the last century of the simulation, indicating that the climate system may be close to equilibrium already after 500 yr of integration. However, significant regional differences between the last century of the simulation and model years 500-599 exist. Further, the difference between simulated and proxy SST is reduced from model years 500-599 to the last century of the simulation. The results of the ENSO variability analysis is also shown to depend on the

  9. A coupled climate model simulation of Marine Isotope Stage 3 stadial climate

    Directory of Open Access Journals (Sweden)

    J. Brandefelt

    2011-06-01

    Full Text Available We present a coupled global climate model (CGCM simulation, integrated for 1500 yr to quasi-equilibrium, of a stadial (cold period within Marine Isotope Stage 3 (MIS 3. The simulated Greenland stadial 12 (GS12; ~44 ka BP annual global mean surface temperature (Ts is 5.5 °C lower than in the simulated recent past (RP climate and 1.3 °C higher than in the simulated Last Glacial Maximum (LGM; 21 ka BP climate. The simulated GS12 is evaluated against proxy data and previous modelling studies of MIS3 stadial climate. We show that the simulated MIS 3 climate, and hence conclusions drawn regarding the dynamics of this climate, is highly model-dependent. The main findings are: (i Proxy sea surface temperatures (SSTs are higher than simulated SSTs in the central North Atlantic, in contrast to earlier simulations of MIS 3 stadial climate in which proxy SSTs were found to be lower than simulated SST. (ii The Atlantic Meridional Overturning Circulation (AMOC slows down by 50 % in the GS12 climate as compared to the RP climate. This slowdown is attained without freshwater forcing in the North Atlantic region, a method used in other studies to force an AMOC shutdown. (iii El-Niño-Southern Oscillation (ENSO teleconnections in mean sea level pressure (MSLP are significantly modified by GS12 and LGM forcing and boundary conditions. (iv Both the mean state and variability of the simulated GS12 is dependent on the equilibration. The annual global mean Ts only changes by 0.10 °C from model years 500–599 to the last century of the simulation, indicating that the climate system may be close to equilibrium already after 500 yr of integration. However, significant regional differences between the last century of the simulation and model years 500–599 exist. Further, the difference between simulated and proxy SST is reduced from model years 500–599 to the last century of the simulation. The results of the ENSO variability

  10. Constraining Transient Climate Sensitivity Using Coupled Climate Model Simulations of Volcanic Eruptions

    KAUST Repository

    Merlis, Timothy M.

    2014-10-01

    Coupled climate model simulations of volcanic eruptions and abrupt changes in CO2 concentration are compared in multiple realizations of the Geophysical Fluid Dynamics Laboratory Climate Model, version 2.1 (GFDL CM2.1). The change in global-mean surface temperature (GMST) is analyzed to determine whether a fast component of the climate sensitivity of relevance to the transient climate response (TCR; defined with the 1%yr-1 CO2-increase scenario) can be estimated from shorter-time-scale climate changes. The fast component of the climate sensitivity estimated from the response of the climate model to volcanic forcing is similar to that of the simulations forced by abrupt CO2 changes but is 5%-15% smaller than the TCR. In addition, the partition between the top-of-atmosphere radiative restoring and ocean heat uptake is similar across radiative forcing agents. The possible asymmetry between warming and cooling climate perturbations, which may affect the utility of volcanic eruptions for estimating the TCR, is assessed by comparing simulations of abrupt CO2 doubling to abrupt CO2 halving. There is slightly less (~5%) GMST change in 0.5 × CO2 simulations than in 2 × CO2 simulations on the short (~10 yr) time scales relevant to the fast component of the volcanic signal. However, inferring the TCR from volcanic eruptions is more sensitive to uncertainties from internal climate variability and the estimation procedure. The response of the GMST to volcanic eruptions is similar in GFDL CM2.1 and GFDL Climate Model, version 3 (CM3), even though the latter has a higher TCR associated with a multidecadal time scale in its response. This is consistent with the expectation that the fast component of the climate sensitivity inferred from volcanic eruptions is a lower bound for the TCR.

  11. SIMULATION OF PRESENT CLIMATE OVER EAST ASIA BY A REGIONAL CLIMATE MODEL

    Institute of Scientific and Technical Information of China (English)

    ZHANG Dong-feng; GAO Xue-jie; OUYANG Li-cheng; DONG Wen-jie

    2008-01-01

    A 15-year simulation of climate over East Asia is conducted with the latest version of a regional climate model RegCM3 nested in one-way mode to the ERA40 Re-analysis data. The performance of themodel in simulating present climate over East Asia and China is investigated. Results show that RegCM3 can reproduce well the atmospheric circulation over East Asia. The simulation of the main distribution patterns of surface air temperature and precipitation over China and their seasonal cycle/evolution, are basically agree with that of the observation. Meanwhile a general cold bias is found in the simulation. AS for the precipitation, the model tends to overestimate the precipitation in northern China while underestimate it in southern China, particularly in winter. In general, the model has better performance in simulating temperature than precipitation.

  12. The Eemian climate simulated by two models of different complexities

    Science.gov (United States)

    Nikolova, Irina; Yin, Qiuzhen; Berger, Andre; Singh, Umesh; Karami, Pasha

    2013-04-01

    The Eemian period, also known as MIS-5, experienced warmer than today climate, reduction in ice sheets and important sea-level rise. These interesting features have made the Eemian appropriate to evaluate climate models when forced with astronomical and greenhouse gas forcings different from today. In this work, we present the simulated Eemian climate by two climate models of different complexities, LOVECLIM (LLN Earth system model of intermediate complexity) and CCSM3 (NCAR atmosphere-ocean general circulation model). Feedbacks from sea ice, vegetation, monsoon and ENSO phenomena are discussed to explain the regional similarities/dissimilarities in both models with respect to the pre-industrial (PI) climate. Significant warming (cooling) over almost all the continents during boreal summer (winter) leads to a largely increased (reduced) seasonal contrast in the northern (southern) hemisphere, mainly due to the much higher (lower) insolation received by the whole Earth in boreal summer (winter). The arctic is warmer than at PI through the whole year, resulting from its much higher summer insolation and its remnant effect in the following fall-winter through the interactions between atmosphere, ocean and sea ice. Regional discrepancies exist in the sea-ice formation zones between the two models. Excessive sea-ice formation in CCSM3 results in intense regional cooling. In both models intensified African monsoon and vegetation feedback are responsible for the cooling during summer in North Africa and on the Arabian Peninsula. Over India precipitation maximum is found further west, while in Africa the precipitation maximum migrates further north. Trees and grassland expand north in Sahel/Sahara, trees being more abundant in the results from LOVECLIM than from CCSM3. A mix of forest and grassland occupies continents and expand deep in the high northern latitudes in line with proxy records. Desert areas reduce significantly in Northern Hemisphere, but increase in North

  13. Climate simulations for 1880-2003 with GISS modelE

    CERN Document Server

    Hansen, J; Bauer, S; Baum, E; Cairns, B; Canuto, V; Chandler, M; Cheng, Y; Cohen, A; Faluvegi, G; Fleming, E; Friend, A; Genio, A D; Hall, T; Jackman, C; Jonas, J; Kelley, M; Kharecha, P; Kiang, N Y; Koch, D; Labow, G; Lacis, A; Lerner, J; Lo, K; Menon, S; Miller, R; Nazarenko, L; Novakov, T; Oinas, V; Perlwitz, J; Rind, D; Romanou, A; Ruedy, R; Russell, G; Sato, M; Schmidt, G A; Schmunk, R; Shindell, D; Stone, P; Streets, D; Sun, S; Tausnev, N; Thresher, D; Unger, N; Yao, M; Zhang, S; Perlwitz, Ja.; Perlwitz, Ju.

    2006-01-01

    We carry out climate simulations for 1880-2003 with GISS modelE driven by ten measured or estimated climate forcings. An ensemble of climate model runs is carried out for each forcing acting individually and for all forcing mechanisms acting together. We compare side-by-side simulated climate change for each forcing, all forcings, observations, unforced variability among model ensemble members, and, if available, observed variability. Discrepancies between observations and simulations with all forcings are due to model deficiencies, inaccurate or incomplete forcings, and imperfect observations. Although there are notable discrepancies between model and observations, the fidelity is sufficient to encourage use of the model for simulations of future climate change. By using a fixed well-documented model and accurately defining the 1880-2003 forcings, we aim to provide a benchmark against which the effect of improvements in the model, climate forcings, and observations can be tested. Principal model deficiencies...

  14. Simulations of LGM climate of East Asia by regional climate model

    Institute of Scientific and Technical Information of China (English)

    郑益群; 于革; 王苏民; 薛滨; 刘华强; 曾新民

    2003-01-01

    Climate conditions in the Last Glacial Maximum (LGM) were remarkably different from the present ones. Adopting a regional climate model (RCM) which has included a detailed land surface scheme, LGM climate of East Asia has been simulated. The effects of vegetation changes on LGM climate have been diagnosed by adding forces of LGM paleovegetation reconstructed from the geological records. The results of the simulations by RCM indicate that large decreases in whole year temperature of East Asia continent caused strongly enhanced winter monsoon and weakened summer monsoon. The strengthening and westward-stretching of the Subtropical High of West-Pacific are the key reasons of decreases of LGM summer precipitation in eastern China. Precipitation and effective precipitation were increased in the Tibetan Plateau and Middle-Asia, while the humid condition in the Tibetan Plateau was mainly caused by increase of precipitation. Accumulated snow of LGM was also increased in the Tibetan Plateau, which was helpful to developing glacier and permafrost. This experiment has simulated that the frozen soil areas extend southward to 30°N. In LGM climate simulation, climate effects caused by external forces were amplified by added paleovegetation, therefore, decreases of temperature, changes of precipitation and snowfall, and other climatic parameters were further strengthened, making the simulation results more approach to geological evidences.

  15. Sensitivity of climate models: Comparison of simulated and observed patterns for past climates

    Energy Technology Data Exchange (ETDEWEB)

    Prell, W.L.; Webb, T. III; Oglesby, R.J.

    1991-10-01

    Predicting the potential climatic effects of increased concentrations of atmospheric carbon dioxide requires the continuing development of climate models. As one index of the magnitude of past climates change, the global mean temperature increase during the past 18,000 years is similar to that predicted for carbon dioxide doubling. Simulating the climate changes of the past 18,000 years, as well as the warmer-than-present climate of 6000 years ago and the climate of the last interglacial, around 126,000 years ago, provides an excellent opportunity to test the models that are being used in global climate change research. During the past several years, we have used paleoclimatic data to test the accuracy of the NCAR CCMO (National Center for Atmospheric Research, Community Climate Model, Version 0), after changing its boundary conditions to those appropriate for past climates. We have assembled near-global paleoclimatic data sets of pollen, lake level, and marine plankton data and calibrated many of the data in terms of climatic variables. We have also developed methods that permit direct quantitative comparisons between the data and model results. Our comparisons have shown both some of the strengths and weaknesses of the model. The research so far has shown the feasibility of our methods for comparing paleoclimatic data and model results. Our research has also shown that comparing the model results with the data is an evolutionary process, because the models, the data, and the methods for comparison are continually being improved. During 1991, we have continued our studies and this Progress Report documents the results to date. During this year, we have completed new modeling experiments, compiled new data sets, made new comparisons between data and model results, and participated in workshops on paleoclimatic modeling. 37 refs.

  16. Evaluation of the Australian Community Climate and Earth-System Simulator Chemistry-Climate Model

    Directory of Open Access Journals (Sweden)

    K. A. Stone

    2015-07-01

    Full Text Available Chemistry climate models are important tools for addressing interactions of composition and climate in the Earth System. In particular, they are used for assessing the combined roles of greenhouse gases and ozone in Southern Hemisphere climate and weather. Here we present an evaluation of the Australian Community Climate and Earth System Simulator-Chemistry Climate Model, focusing on the Southern Hemisphere and the Australian region. This model is used for the Australian contribution to the international Chemistry-Climate Model Initiative, which is soliciting hindcast, future projection and sensitivity simulations. The model simulates global total column ozone (TCO distributions accurately, with a slight delay in the onset and recovery of springtime Antarctic ozone depletion, and consistently higher ozone values. However, October averaged Antarctic TCO from 1960 to 2010 show a similar amount of depletion compared to observations. A significant innovation is the evaluation of simulated vertical profiles of ozone and temperature with ozonesonde data from Australia, New Zealand and Antarctica from 38 to 90° S. Excess ozone concentrations (up to 26.4 % at Davis during winter and stratospheric cold biases (up to 10.1 K at the South Pole outside the period of perturbed springtime ozone depletion are seen during all seasons compared to ozonesondes. A disparity in the vertical location of ozone depletion is seen: centered around 100 hPa in ozonesonde data compared to above 50 hPa in the model. Analysis of vertical chlorine monoxide profiles indicates that colder Antarctic stratospheric temperatures (possibly due to reduced mid-latitude heat flux are artificially enhancing polar stratospheric cloud formation at high altitudes. The models inability to explicitly simulated supercooled ternary solution may also explain the lack of depletion at lower altitudes. The simulated Southern Annular Mode (SAM index compares well with ERA-Interim data. Accompanying

  17. Land use effects on climate in China as simulated by a regional climate model

    Institute of Scientific and Technical Information of China (English)

    GAO XueJie; ZHANG DongFeng; CHEN ZhongXin; J.S.PAL; F. GIORGI

    2007-01-01

    A regional climate model (RegCM3)nested within ERA40 re-analyzed data is used to investigate the climate effects of land use change over China. Two 15-year simulations (1987-2001),one with current land use and the other with potential vegetation cover without human intervention, are conducted for a domain encompassing China. The climate impacts of land use change are assessed from the difference between the two simulations. Results show that the current land use (modified by anthropogenic activities) influences local climate as simulated by the model through the reinforcement of the monsoon circulation in both the winter and summer seasons and through changes of the surface energy budget. In winter. Land use change leads to reduced precipitation and decreased surface air temperature south of the Yangtze River, and increased precipitation north of the Yangtze River. Land use change significantly affects summer climate in southern China, yielding increased precipitation over the region, decreased temperature along the Yangtze River and increased temperature in the South China area (south-end of China).In summer, a reduction of precipitation over northern China and a temperature rise over Northwest China are also simulated. Both daily maximum and minimum temperatures are affected in the simulations. In general, the current land use in China leads to enhanced mean annual precipitation and decreased annual temperature over south China along with decreased precipitation over North China.

  18. Land use effects on climate in China as simulated by a regional climate model

    Institute of Scientific and Technical Information of China (English)

    J.S.PAL; F.GIORGI

    2007-01-01

    A regional climate model (RegCM3) nested within ERA40 re-analyzed data is used to investigate the climate effects of land use change over China. Two 15-year simulations (1987―2001), one with current land use and the other with potential vegetation cover without human intervention, are conducted for a domain encompassing China. The climate impacts of land use change are assessed from the difference between the two simulations. Results show that the current land use (modified by anthropogenic ac- tivities) influences local climate as simulated by the model through the reinforcement of the monsoon circulation in both the winter and summer seasons and through changes of the surface energy budget. In winter, land use change leads to reduced precipitation and decreased surface air temperature south of the Yangtze River, and increased precipitation north of the Yangtze River. Land use change signifi- cantly affects summer climate in southern China, yielding increased precipitation over the region, de- creased temperature along the Yangtze River and increased temperature in the South China area (south-end of China). In summer, a reduction of precipitation over northern China and a temperature rise over Northwest China are also simulated. Both daily maximum and minimum temperatures are affected in the simulations. In general, the current land use in China leads to enhanced mean annual precipitation and decreased annual temperature over south China along with decreased precipitation over North China.

  19. Decadal Variability of Clouds and Comparison with Climate Model Simulations

    Science.gov (United States)

    Su, H.; Shen, T. J.; Jiang, J. H.; Yung, Y. L.

    2014-12-01

    An apparent climate regime shift occurred around 1998/1999, when the steady increase of global-mean surface temperature appeared to hit a hiatus. Coherent decadal variations are found in atmospheric circulation and hydrological cycles. Using 30-year cloud observations from the International Satellite Cloud Climatology Project, we examine the decadal variability of clouds and associated cloud radiative effects on surface warming. Empirical Orthogonal Function analysis is performed. After removing the seasonal cycle and ENSO signal in the 30-year data, we find that the leading EOF modes clearly represent a decadal variability in cloud fraction, well correlated with the indices of Pacific Decadal Oscillation (PDO) and Atlantic Multidecadal Oscillation (AMO). The cloud radiative effects associated with decadal variations of clouds suggest a positive cloud feedback, which would reinforce the global warming hiatus by a net cloud cooling after 1998/1999. Climate model simulations driven by observed sea surface temperature are compared with satellite observed cloud decadal variability. Copyright:

  20. Simulation of Effects of Land Use Change on Climate in China by a Regional Climate Model

    Institute of Scientific and Technical Information of China (English)

    高学杰; 罗勇; 林万涛; 赵宗慈; FilippoGIORGI

    2003-01-01

    Climate effects of land use change in China as simulated by a regional climate model (RegCM2)are investigated. The model is nested in one-way mode within a global coupled atmosphere-ocean model(CSIRO R21L9 AOGCM). Two multi-year simulations, one with current land use and the other with potential vegetation cover, are conducted. Statistically significant changes of precipitation, surface air temperature, and daily maximum and daily minimum temperature are analyzed based on the difference between the two simulations. The simulated effects of land use change over China include a decrease of mean annual precipitation over Northwest China, a region with a prevalence of arid and semi-arid areas;an increase of mean annual surfaoe air temperature over some areas; and a decrease of temperature along coastal areas. Summer mean daily maximum temperature increases in many locations, while winter mean daily minimum temperature decreases in East China and increases in Northwest China. The upper soil moisture decreases significantly across China. The results indicate that the same land use change may cause different climate effects in different regions depending on the surrounding environment and climate characteristics.

  1. Uncertainties in the regional climate models simulations of South-Asian summer monsoon and climate change

    Science.gov (United States)

    Syed, F. S.; Iqbal, Waheed; Syed, Ahsan Ali Bukhari; Rasul, G.

    2014-04-01

    The uncertainties in the regional climate models (RCMs) are evaluated by analyzing the driving global data of ERA40 reanalysis and ECHAM5 general circulation models, and the downscaled data of two RCMs (RegCM4 and PRECIS) over South-Asia for the present day simulation (1971-2000) of South-Asian summer monsoon. The differences between the observational datasets over South-Asia are also analyzed. The spatial and the quantitative analysis over the selected climatic regions of South-Asia for the mean climate and the inter-annual variability of temperature, precipitation and circulation show that the RCMs have systematic biases which are independent from different driving datasets and seems to come from the physics parameterization of the RCMs. The spatial gradients and topographically-induced structure of climate are generally captured and simulated values are within a few degrees of the observed values. The biases in the RCMs are not consistent with the biases in the driving fields and the models show similar spatial patterns after downscaling different global datasets. The annual cycle of temperature and rainfall is well simulated by the RCMs, however the RCMs are not able to capture the inter-annual variability. ECHAM5 is also downscaled for the future (2071-2100) climate under A1B emission scenario. The climate change signal is consistent between ECHAM5 and RCMs. There is warming over all the regions of South-Asia associated with increasing greenhouse gas concentrations and the increase in summer mean surface air temperature by the end of the century ranges from 2.5 to 5 °C, with maximum warming over north western parts of the domain and 30 % increase in rainfall over north eastern India, Bangladesh and Myanmar.

  2. Climate simulations for the last interglacial period by means of climate models of different complexity

    Energy Technology Data Exchange (ETDEWEB)

    Montoya, M.L. [GKSS-Forschungszentrum Geesthacht GmbH (Germany). Inst. fuer Hydrophysik

    1999-07-01

    Climatic conditions during the lst interglacial (125,000 years before present) are investigated with two climate models of different complexity: The atmosphere-ocean general circulation model ECHAM-1/LSG and the climate system model of intermediate complexity CLIMBER-2. In particular the role of vegetation at the last interglacial maximum, and its importance for a consistent simulation of the Mid-Holocene climate, has been investigated (EU project ASPEN: Air-Sea Wave Processes in Climate Change Models). Comparison of the results of the two models reveals a broad agreement in most large-scale features. Nevertheless, discrepancies are also detected. Essentially, the models differ in their ocean circulation responses. Profiting of the fast turnaround time of CLIMBER-2, a number of sensitivity experiments have been performed to try to explain the possible reasons for these differences, and to analyze additional effects not included in the previous simulations. In particular, the role of vegetation at the last interglacial maximum has been investigated. Comparison of the simulated responses against CLIMAP reconstructed SSTs for Marine Isotope Stage 5e shows a satisfactory agreement within the data uncertainties. (orig.) [German] Die klimatischen Bedingungen waehrend der letzten interglazialen Periode (vor 125 000 Jahren) werden anhand zweier Klimamodelle unterschiedlicher Komplexitaet untersucht: Dem Ozean-Atmosphaere gekoppelten allgemeinen Zirkulationsmodell ECHAM-1/LSG und dem Klimasystemmodell mittlerer Komplexitaet CLIMBER-2. Inbesondere wurde die Rolle der Vegetation in der letzten interglazialen Periode und ihre Bedeutung fuer eine konsistente Simulation des mittelholozaenischen Klimas untersucht (EU-Projekt ASPEN: Air-Sea Wave Processes in Climate Change Models - 'Klimavariationen in historischen Zeiten'). Der Vergleich der Ergebnisse beider Modelle zeigt eine gute Uebereinstimmung der meisten der grossskaligen Eigenschaften, allerdings zeigen sich

  3. Regional-Scale Climate Change: Observations and Model Simulations

    Energy Technology Data Exchange (ETDEWEB)

    Bradley, Raymond S; Diaz, Henry F

    2010-12-14

    This collaborative proposal addressed key issues in understanding the Earth's climate system, as highlighted by the U.S. Climate Science Program. The research focused on documenting past climatic changes and on assessing future climatic changes based on suites of global and regional climate models. Geographically, our emphasis was on the mountainous regions of the world, with a particular focus on the Neotropics of Central America and the Hawaiian Islands. Mountain regions are zones where large variations in ecosystems occur due to the strong climate zonation forced by the topography. These areas are particularly susceptible to changes in critical ecological thresholds, and we conducted studies of changes in phonological indicators based on various climatic thresholds.

  4. Using Transport Diagnostics to Understand Chemistry Climate Model Ozone Simulations

    Science.gov (United States)

    Strahan, S. E.; Douglass, A. R.; Stolarski, R. S.; Akiyoshi, H.; Bekki, S.; Braesicke, P.; Butchart, N.; Chipperfield, M. P.; Cugnet, D.; Dhomse, S.; Frith, S. M.; Gettleman, A.; Hardiman, S. C.; Kinnison, D. E.; Lamarque, J.-F.; Mancini, E.; Marchand, M.; Michou, M.; Morgenstern, O.; Nakamura, T.; Olivie, D.; Pawson, S.; Pitari, G.; Plummer, D. A.; Pyle, J. A.

    2010-01-01

    We demonstrate how observations of N2O and mean age in the tropical and midlatitude lower stratosphere (LS) can be used to identify realistic transport in models. The results are applied to 15 Chemistry Climate Models (CCMs) participating in the 2010 WMO assessment. Comparison of the observed and simulated N2O/mean age relationship identifies models with fast or slow circulations and reveals details of model ascent and tropical isolation. The use of this process-oriented N2O/mean age diagnostic identifies models with compensating transport deficiencies that produce fortuitous agreement with mean age. We compare the diagnosed model transport behavior with a model's ability to produce realistic LS O3 profiles in the tropics and midlatitudes. Models with the greatest tropical transport problems show the poorest agreement with observations. Models with the most realistic LS transport agree more closely with LS observations and each other. We incorporate the results of the chemistry evaluations in the SPARC CCMVal Report (2010) to explain the range of CCM predictions for the return-to-1980 dates for global (60 S-60 N) and Antarctic column ozone. Later (earlier) Antarctic return dates are generally correlated to higher (lower) vortex Cl(sub y) levels in the LS, and vortex Cl(sub y) is generally correlated with the model's circulation although model Cl(sub y) chemistry or Cl(sub y) conservation can have a significant effect. In both regions, models that have good LS transport produce a smaller range of predictions for the return-to-1980 ozone values. This study suggests that the current range of predicted return dates is unnecessarily large due to identifiable model transport deficiencies.

  5. Climate simulations for 1880-2003 with GISS modelE

    Energy Technology Data Exchange (ETDEWEB)

    Hansen, J. [NASA Goddard Inst. for Space Studies, New York, NY (United States)]|[Columbia Univ. Earth Inst., New York, NY (United States); Sato, M.; Kharecha, P.; Nazarenko, L.; Aleinov, I.; Bauer, S.; Chandler, M.; Faluvegi, G.; Jonas, J.; Lerner, J.; Perlwitz, J.; Unger, N.; Zhang, S. [Columbia Univ. Earth Inst., New York, NY (United States); Ruedy, R.; Lo, K.; Cheng, Y.; Oinas, V.; Schmunk, R.; Tausnev, N.; Yao, M. [Sigma Space Partners LLC, New York, NY (United States); Lacis, A.; Schmidt, G.A.; Del Genio, A.; Rind, D.; Romanou, A.; Shindell, D. [NASA Goddard Inst. for Space Studies, New York, NY (United States)]|[Columbia Univ., Dept. of Earth and Environmental Sciences, New York, NY (United States); Miller, R.; Hall, T. [NASA Goddard Inst. for Space Studies, New York, NY (United States)]|[Columbia Univ., Dept. of Applied Physics and Applied Mathematics, New York, NY (United States); Russell, G.; Canuto, V.; Kiang, N.Y. [NASA Goddard Inst. for Space Studies, New York, NY (United States); Baum, E.; Cohen, A. [Clean Air Task Force, Boston, MA (United States); Cairns, B.; Perlwitz, J. [Columbia Univ., Dept. of Applied Physics and Applied Mathematics, New York, NY (United States); Fleming, E.; Jackman, C.; Labow, G. [NASA Goddard Space Flight Center, Greenbelt, MD (United States); Friend, A.; Kelley, M. [Lab. des Sciences du Climat et de l' Environnement, Gif-sur-Yvette (France); Koch, D. [Columbia Univ. Earth Inst., New York, NY (United States)]|[Yale Univ., Dept. of Geology, New Haven, CT (United States); Menon, S.; Novakov, T. [Lawrence Berkeley National Lab., CA (United States); Stone, P. [Massachusetts Inst. of Tech., Cambridge, MA (United States); Sun, S. [NASA Goddard Inst. for Space Studies, New York, NY (United States)]|[Massachusetts Inst. of Tech., Cambridge, MA (United States); Streets, D. [Argonne National Lab., IL (United States); Thresher, D. [Columbia Univ., Dept. of Earth and Environmental Sciences, New York, NY (United States)

    2007-12-15

    We carry out climate simulations for 1880-2003 with GISS modelE driven by ten measured or estimated climate forcings. An ensemble of climate model runs is carried out for each forcing acting individually and for all forcing mechanisms acting together. We compare side-by-side simulated climate change for each forcing, all forcings, observations, unforced variability among model ensemble members, and, if available, observed variability. Discrepancies between observations and simulations with all forcings are due to model deficiencies, inaccurate or incomplete forcings, and imperfect observations. Although there are notable discrepancies between model and observations, the fidelity is sufficient to encourage use of the model for simulations of future climate change. By using a fixed well-documented model and accurately defining the 1880-2003 forcings, we aim to provide a benchmark against which the effect of improvements in the model, climate forcings, and observations can be tested. Principal model deficiencies include unrealistically weak tropical El Nino-like variability and a poor distribution of sea ice, with too much sea ice in the Northern Hemisphere and too little in the Southern Hemisphere. Greatest uncertainties in the forcings are the temporal and spatial variations of anthropogenic aerosols and their indirect effects on clouds. (orig.)

  6. Regional climate model simulations indicate limited climatic impacts by operational and planned European wind farms.

    Science.gov (United States)

    Vautard, Robert; Thais, Françoise; Tobin, Isabelle; Bréon, François-Marie; Devezeaux de Lavergne, Jean-Guy; Colette, Augustin; Yiou, Pascal; Ruti, Paolo Michele

    2014-01-01

    The rapid development of wind energy has raised concerns about environmental impacts. Temperature changes are found in the vicinity of wind farms and previous simulations have suggested that large-scale wind farms could alter regional climate. However, assessments of the effects of realistic wind power development scenarios at the scale of a continent are missing. Here we simulate the impacts of current and near-future wind energy production according to European Union energy and climate policies. We use a regional climate model describing the interactions between turbines and the atmosphere, and find limited impacts. A statistically significant signal is only found in winter, with changes within ±0.3 °C and within 0-5% for precipitation. It results from the combination of local wind farm effects and changes due to a weak, but robust, anticyclonic-induced circulation over Europe. However, the impacts remain much weaker than the natural climate interannual variability and changes expected from greenhouse gas emissions.

  7. Notes of Numerical Simulation of Summer Rainfall in China with a Regional Climate Model REMO

    Institute of Scientific and Technical Information of China (English)

    CUI Xuefeng; HUANG Gang; CHEN Wen

    2008-01-01

    Regional climate models are major tools for regional climate simulation and their output are mostly used for climate impact studies. Notes are reported from a series of numerical simulations of summer rainfall in China with a regional climate model. Domain sizes and running modes are major foci. The results reveal that the model in forecast mode driven by "perfect" boundaries could reasonably represent the inter-annual differences: heavy rainfall along the Yangtze River in 1998 and dry conditions in 1997. Model simulation in climate mode differs to a greater extent from observation than that in forecast mode. This may be due to the fact that in climate mode it departs further from the driving fields and relies more on internal model dynamical processes. A smaller domain in climate mode outperforms a larger one. Further development of model parameterizations including dynamic vegetation are encouraged in future studies.

  8. Simulations of present and future climates in the western U.S. with four nested regional climate models

    Energy Technology Data Exchange (ETDEWEB)

    Duffy, P B; Arritt, R W; Coquard, J; Gutowski, W; Han, J; Iorio, J; Kim, J; Leung, L R; Roads, J; Zeledon, E

    2004-06-15

    We analyze simulations of present and future climates in the western U.S. performed with four regional climate models (RCMs) nested within two global ocean-atmosphere climate models. Our primary goal is to assess the range of regional climate responses to increased greenhouse gases in available RCM simulations. The four RCMs used different geographical domains, different increased greenhouse gas scenarios for future-climate simulations, and (in some cases) different lateral boundary conditions. For simulations of the present climate, we compare RCM results to observations and to results of the GCM that provided lateral boundary conditions to the RCM. For future-climate (increased greenhouse gas) simulations, we compare RCM results to each other and to results of the driving GCMs. When results are spatially averaged over the western U.S., we find that the results of each RCM closely follow those of the driving GCM in the same region, in both present and future climates. In present-climate simulations, the RCMs have biases in spatially-averaged simulated precipitation and near-surface temperature that seem to be very close to those of the driving GCMs. In future-climate simulations, the spatially-averaged RCM-projected responses in precipitation and near-surface temperature are also very close to those of the respective driving GCMs. Precipitation responses predicted by the RCMs are in many regions not statistically significant compared to interannual variability. Where the predicted precipitation responses are statistically significant, they are positive. The models agree that near-surface temperatures will increase, but do not agree on the spatial pattern of this increase. The four RCMs produce very different estimates of water content of snow in the present climate, and of the change in this water content in response to increased greenhouse gases.

  9. Simulation of black carbon in snow and its climate impact in the Canadian Global Climate Model

    Science.gov (United States)

    Namazi, M.; von Salzen, K.; Cole, J. N. S.

    2015-09-01

    A new physically based parameterisation of black carbon (BC) in snow was developed and implemented in the Canadian Atmospheric Global Climate Model (CanAM4.2). Simulated BC snow mixing ratios and BC snow radiative forcings are in good agreement with measurements and results from other models. Simulations with the improved model yield considerable trends in regional BC concentrations in snow and BC snow radiative forcings during the time period from 1950-1959 to 2000-2009. Increases in radiative forcings for Asia and decreases for Europe and North America are found to be associated with changes in BC emissions. Additional sensitivity simulations were performed in order to study the impact of BC emission changes between 1950-1959 and 2000-2009 on surface albedo, snow cover fraction, and surface air temperature. Results from these simulations indicate that impacts of BC emission changes on snow albedos between these 2 decades are small and not significant. Overall, changes in BC concentrations in snow have much smaller impacts on the cryosphere than the net warming surface air temperatures during the second half of the 20th century.

  10. Simulation of black carbon in snow and its climate impact in the Canadian Global Climate Model

    Directory of Open Access Journals (Sweden)

    M. Namazi

    2015-07-01

    Full Text Available A new physically-based parameterization of black carbon (BC in snow was developed and implemented in the Canadian Atmospheric Global Climate Model (CanAM4.2. Simulated BC snow mixing ratios and BC snow radiative forcings are in good agreement with measurements and results from other models. Simulations with the improved model yield considerable trends in regional BC concentrations in snow and BC snow radiative forcings during the time period from 1950–1959 to 2000–2009. Increases in radiative forcings for Asia and decreases for Europe and North America are found to be associated with changes in BC emissions. Additional sensitivity simulations were performed in order to study the impact of BC emission changes between 1950–1959 and 2000–2009 on surface albedo, snow cover fraction, and surface air temperature. Results from these simulations indicate that impacts of BC emission changes on snow albedos between these two decades are small and not significant. Overall, changes in BC concentrations in snow have much smaller impacts on the cryosphere than the net warming surface air temperatures during the second half of the 20th century.

  11. Hydrologic modeling using elevationally adjusted NARR and NARCCAP regional climate-model simulations: Tucannon River, Washington

    Science.gov (United States)

    Praskievicz, Sarah; Bartlein, Patrick

    2014-09-01

    An emerging approach to downscaling the projections from General Circulation Models (GCMs) to scales relevant for basin hydrology is to use output of GCMs to force higher-resolution Regional Climate Models (RCMs). With spatial resolution often in the tens of kilometers, however, even RCM output will likely fail to resolve local topography that may be climatically significant in high-relief basins. Here we develop and apply an approach for downscaling RCM output using local topographic lapse rates (empirically-estimated spatially and seasonally variable changes in climate variables with elevation). We calculate monthly local topographic lapse rates from the 800-m Parameter-elevation Regressions on Independent Slopes Model (PRISM) dataset, which is based on regressions of observed climate against topographic variables. We then use these lapse rates to elevationally correct two sources of regional climate-model output: (1) the North American Regional Reanalysis (NARR), a retrospective dataset produced from a regional forecasting model constrained by observations, and (2) a range of baseline climate scenarios from the North American Regional Climate Change Assessment Program (NARCCAP), which is produced by a series of RCMs driven by GCMs. By running a calibrated and validated hydrologic model, the Soil and Water Assessment Tool (SWAT), using observed station data and elevationally-adjusted NARR and NARCCAP output, we are able to estimate the sensitivity of hydrologic modeling to the source of the input climate data. Topographic correction of regional climate-model data is a promising method for modeling the hydrology of mountainous basins for which no weather station datasets are available or for simulating hydrology under past or future climates.

  12. Climate Models

    Science.gov (United States)

    Druyan, Leonard M.

    2012-01-01

    Climate models is a very broad topic, so a single volume can only offer a small sampling of relevant research activities. This volume of 14 chapters includes descriptions of a variety of modeling studies for a variety of geographic regions by an international roster of authors. The climate research community generally uses the rubric climate models to refer to organized sets of computer instructions that produce simulations of climate evolution. The code is based on physical relationships that describe the shared variability of meteorological parameters such as temperature, humidity, precipitation rate, circulation, radiation fluxes, etc. Three-dimensional climate models are integrated over time in order to compute the temporal and spatial variations of these parameters. Model domains can be global or regional and the horizontal and vertical resolutions of the computational grid vary from model to model. Considering the entire climate system requires accounting for interactions between solar insolation, atmospheric, oceanic and continental processes, the latter including land hydrology and vegetation. Model simulations may concentrate on one or more of these components, but the most sophisticated models will estimate the mutual interactions of all of these environments. Advances in computer technology have prompted investments in more complex model configurations that consider more phenomena interactions than were possible with yesterday s computers. However, not every attempt to add to the computational layers is rewarded by better model performance. Extensive research is required to test and document any advantages gained by greater sophistication in model formulation. One purpose for publishing climate model research results is to present purported advances for evaluation by the scientific community.

  13. Formulation of an ocean model for global climate simulations

    Directory of Open Access Journals (Sweden)

    S. M. Griffies

    2005-01-01

    Full Text Available This paper summarizes the formulation of the ocean component to the Geophysical Fluid Dynamics Laboratory's (GFDL climate model used for the 4th IPCC Assessment (AR4 of global climate change. In particular, it reviews the numerical schemes and physical parameterizations that make up an ocean climate model and how these schemes are pieced together for use in a state-of-the-art climate model. Features of the model described here include the following: (1 tripolar grid to resolve the Arctic Ocean without polar filtering, (2 partial bottom step representation of topography to better represent topographically influenced advective and wave processes, (3 more accurate equation of state, (4 three-dimensional flux limited tracer advection to reduce overshoots and undershoots, (5 incorporation of regional climatological variability in shortwave penetration, (6 neutral physics parameterization for representation of the pathways of tracer transport, (7 staggered time stepping for tracer conservation and numerical efficiency, (8 anisotropic horizontal viscosities for representation of equatorial currents, (9 parameterization of exchange with marginal seas, (10 incorporation of a free surface that accomodates a dynamic ice model and wave propagation, (11 transport of water across the ocean free surface to eliminate unphysical ``virtual tracer flux' methods, (12 parameterization of tidal mixing on continental shelves. We also present preliminary analyses of two particularly important sensitivities isolated during the development process, namely the details of how parameterized subgridscale eddies transport momentum and tracers.

  14. Very high resolution regional climate model simulations over Greenland: Identifying added value

    DEFF Research Database (Denmark)

    Lucas-Picher, P.; Wulff-Nielsen, M.; Christensen, J.H.;

    2012-01-01

    This study presents two simulations of the climate over Greenland with the regional climate model (RCM) HIRHAM5 at 0.05° and 0.25° resolution driven at the lateral boundaries by the ERA-Interim reanalysis for the period 1989–2009. These simulations are validated against observations from meteorol...

  15. Spontaneous abrupt climate change due to an atmospheric blocking–sea-ice–ocean feedback in an unforced climate model simulation

    NARCIS (Netherlands)

    Drijfhout, S.S.; Gleeson, E.; Dijkstra, H.A.; Livina, V.

    2013-01-01

    Abrupt climate change is abundant in geological records, but climate models rarely have been able to simulate such events in response to realistic forcing. Here we report on a spontaneous abrupt cooling event, lasting for more than a century, with a temperature anomaly similar to that of the Little

  16. An evaluation of 20th century climate for the Southeastern United States as simulated by Coupled Model Intercomparison Project Phase 5 (CMIP5) global climate models

    Science.gov (United States)

    David E. Rupp,

    2016-05-05

    The 20th century climate for the Southeastern United States and surrounding areas as simulated by global climate models used in the Coupled Model Intercomparison Project Phase 5 (CMIP5) was evaluated. A suite of statistics that characterize various aspects of the regional climate was calculated from both model simulations and observation-based datasets. CMIP5 global climate models were ranked by their ability to reproduce the observed climate. Differences in the performance of the models between regions of the United States (the Southeastern and Northwestern United States) warrant a regional-scale assessment of CMIP5 models.

  17. The Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP): Overview and Description of Models, Simulations and Climate Diagnostics

    Science.gov (United States)

    Lamarque, J.-F.; Shindell, D. T.; Naik, V.; Plummer, D.; Josse, B.; Righi, M.; Rumbold, S. T.; Schulz, M.; Skeie, R. B.; Strode, S.; Young, P. J.; Cionni, I.; Dalsoren, S.; Eyring, V.; Bergmann, D.; Cameron-Smith, P.; Collins, W. J.; Doherty, R.; Faluvegi, G.; Folberth, G.; Ghan, S. J.; Horowitz, L. W.; Lee, Y. H.; MacKenzie, I. A.; Nagashima, T.

    2013-01-01

    The Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP) consists of a series of time slice experiments targeting the long-term changes in atmospheric composition between 1850 and 2100, with the goal of documenting composition changes and the associated radiative forcing. In this overview paper, we introduce the ACCMIP activity, the various simulations performed (with a requested set of 14) and the associated model output. The 16 ACCMIP models have a wide range of horizontal and vertical resolutions, vertical extent, chemistry schemes and interaction with radiation and clouds. While anthropogenic and biomass burning emissions were specified for all time slices in the ACCMIP protocol, it is found that the natural emissions are responsible for a significant range across models, mostly in the case of ozone precursors. The analysis of selected present-day climate diagnostics (precipitation, temperature, specific humidity and zonal wind) reveals biases consistent with state-of-the-art climate models. The model-to- model comparison of changes in temperature, specific humidity and zonal wind between 1850 and 2000 and between 2000 and 2100 indicates mostly consistent results. However, models that are clear outliers are different enough from the other models to significantly affect their simulation of atmospheric chemistry.

  18. Improved Regional Climate Model Simulation of Precipitation by a Dynamical Coupling to a Hydrology Model

    DEFF Research Database (Denmark)

    Larsen, Morten Andreas Dahl; Drews, Martin; Hesselbjerg Christensen, Jens;

    The complexity of precipitation processes makes it difficult for climate models to reliably simulate precipitation, particularly at sub-grid scales, where the important processes are associated with detailed land-atmosphere feedbacks like the vertical circulations driven by latent heat that affec...... including a detailed 3D redistribution of sub- and land surface water have a significant potential for improving climate projections even diminishing the need for bias correction in climate-hydrology studies.......The complexity of precipitation processes makes it difficult for climate models to reliably simulate precipitation, particularly at sub-grid scales, where the important processes are associated with detailed land-atmosphere feedbacks like the vertical circulations driven by latent heat that affect......- and river flow as well as land surface-atmosphere fluxes of water (evapotranspiration) and energy - significantly reduces precipitation bias compared to the regional climate model alone. For a six year simulation period (2004 – 2010) covering a 2500 km2 catchment substantial improvements in the reproduction...

  19. The Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP: overview and description of models, simulations and climate diagnostics

    Directory of Open Access Journals (Sweden)

    J.-F. Lamarque

    2012-08-01

    Full Text Available The Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP consists of a series of timeslice experiments targeting the long-term changes in atmospheric composition between 1850 and 2100, with the goal of documenting radiative forcing and the associated composition changes. Here we introduce the various simulations performed under ACCMIP and the associated model output. The ACCMIP models have a wide range of horizontal and vertical resolutions, vertical extent, chemistry schemes and interaction with radiation and clouds. While anthropogenic and biomass burning emissions were specified for all time slices in the ACCMIP protocol, it is found that the natural emissions lead to a significant range in emissions, mostly for ozone precursors. The analysis of selected present-day climate diagnostics (precipitation, temperature, specific humidity and zonal wind reveals biases consistent with state-of-the-art climate models. The model-to-model comparison of changes in temperature, specific humidity and zonal wind between 1850 and 2000 and between 2000 and 2100 indicates mostly consistent results, but with outliers different enough to possibly affect their representation of climate impact on chemistry.

  20. Effect of model resolution on a regional climate model simulation over southeast Australia

    KAUST Repository

    Evans, J. P.

    2013-03-26

    Dynamically downscaling climate projections from global climate models (GCMs) for use in impacts and adaptation research has become a common practice in recent years. In this study, the CSIRO Mk3.5 GCM is downscaled using the Weather Research and Forecasting (WRF) regional climate model (RCM) to medium (50 km) and high (10 km) resolution over southeast Australia. The influence of model resolution on the present-day (1985 to 2009) modelled regional climate and projected future (2075 to 2099) changes are examined for both mean climate and extreme precipitation characteristics. Increasing model resolution tended to improve the simulation of present day climate, with larger improvements in areas affected by mountains and coastlines. Examination of circumstances under which increasing the resolution decreased performance revealed an error in the GCM circulation, the effects of which had been masked by the coarse GCM topography. Resolution modifications to projected changes were largest in regions with strong topographic and coastline influences, and can be large enough to change the sign of the climate change projected by the GCM. Known physical mechanisms for these changes included orographic uplift and low-level blocking of air-masses caused by mountains. In terms of precipitation extremes, the GCM projects increases in extremes even when the projected change in the mean was a decrease: but this was not always true for the higher resolution models. Thus, while the higher resolution RCM climate projections often concur with the GCM projections, there are times and places where they differ significantly due to their better representation of physical processes. It should also be noted that the model resolution can modify precipitation characteristics beyond just its mean value.

  1. The research in climate system modeling, simulating and forecasting

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    @@ The major point of the World Climate Research Program (WCRP) is to predict the real-time climate change in seasons and years. Climate disasters in China occurred frequently, and resulted in a 200 billion RMB lost annually.

  2. Using statistical model to simulate the impact of climate change on maize yield with climate and crop uncertainties

    Science.gov (United States)

    Zhang, Yi; Zhao, Yanxia; Wang, Chunyi; Chen, Sining

    2016-09-01

    Assessment of the impact of climate change on crop productions with considering uncertainties is essential for properly identifying and decision-making agricultural practices that are sustainable. In this study, we employed 24 climate projections consisting of the combinations of eight GCMs and three emission scenarios representing the climate projections uncertainty, and two crop statistical models with 100 sets of parameters in each model representing parameter uncertainty within the crop models. The goal of this study was to evaluate the impact of climate change on maize (Zea mays L.) yield at three locations (Benxi, Changling, and Hailun) across Northeast China (NEC) in periods 2010-2039 and 2040-2069, taking 1976-2005 as the baseline period. The multi-models ensembles method is an effective way to deal with the uncertainties. The results of ensemble simulations showed that maize yield reductions were less than 5 % in both future periods relative to the baseline. To further understand the contributions of individual sources of uncertainty, such as climate projections and crop model parameters, in ensemble yield simulations, variance decomposition was performed. The results indicated that the uncertainty from climate projections was much larger than that contributed by crop model parameters. Increased ensemble yield variance revealed the increasing uncertainty in the yield simulation in the future periods.

  3. Correction of biased climate simulated by biased physics through parameter estimation in an intermediate coupled model

    Science.gov (United States)

    Zhang, Xuefeng; Zhang, Shaoqing; Liu, Zhengyu; Wu, Xinrong; Han, Guijun

    2016-09-01

    Imperfect physical parameterization schemes are an important source of model bias in a coupled model and adversely impact the performance of model simulation. With a coupled ocean-atmosphere-land model of intermediate complexity, the impact of imperfect parameter estimation on model simulation with biased physics has been studied. Here, the biased physics is induced by using different outgoing longwave radiation schemes in the assimilation and "truth" models. To mitigate model bias, the parameters employed in the biased longwave radiation scheme are optimized using three different methods: least-squares parameter fitting (LSPF), single-valued parameter estimation and geography-dependent parameter optimization (GPO), the last two of which belong to the coupled model parameter estimation (CMPE) method. While the traditional LSPF method is able to improve the performance of coupled model simulations, the optimized parameter values from the CMPE, which uses the coupled model dynamics to project observational information onto the parameters, further reduce the bias of the simulated climate arising from biased physics. Further, parameters estimated by the GPO method can properly capture the climate-scale signal to improve the simulation of climate variability. These results suggest that the physical parameter estimation via the CMPE scheme is an effective approach to restrain the model climate drift during decadal climate predictions using coupled general circulation models.

  4. Clouds and Precipitation Simulated by the US DOE Accelerated Climate Modeling for Energy (ACME)

    Science.gov (United States)

    Xie, S.; Lin, W.; Yoon, J. H.; Ma, P. L.; Rasch, P. J.; Ghan, S.; Zhang, K.; Zhang, Y.; Zhang, C.; Bogenschutz, P.; Gettelman, A.; Larson, V. E.; Neale, R. B.; Park, S.; Zhang, G. J.

    2015-12-01

    A new US Department of Energy (DOE) climate modeling effort is to develop an Accelerated Climate Model for Energy (ACME) to accelerate the development and application of fully coupled, state-of-the-art Earth system models for scientific and energy application. ACME is a high-resolution climate model with a 0.25 degree in horizontal and more than 60 levels in the vertical. It starts from the Community Earth System Model (CESM) with notable changes to its physical parameterizations and other components. This presentation provides an overview on the ACME model's capability in simulating clouds and precipitation and its sensitivity to convection schemes. Results with using several state-of-the-art cumulus convection schemes, including those unified parameterizations that are being developed in the climate community, will be presented. These convection schemes are evaluated in a multi-scale framework including both short-range hindcasts and free-running climate simulations with both satellite data and ground-based measurements. Running climate model in short-range hindcasts has been proven to be an efficient way to understand model deficiencies. The analysis is focused on those systematic errors in clouds and precipitation simulations that are shared in many climate models. The goal is to understand what model deficiencies might be primarily responsible for these systematic errors.

  5. Climate in Sweden during the past millennium - Evidence from proxy data, instrumental data and model simulations

    Energy Technology Data Exchange (ETDEWEB)

    Moberg, Anders; Gouirand, Isabelle; Schoning, Kristian; Wohlfarth, Barbara [Stockholm Univ. (Sweden). Dept. of Physical Geography and Quaternary Geology; Kjellstroem, Erik; Rummukainen, Markku [Swedish Meteorological and Hydrological Inst., Norrkoeping (Sweden). Rossby Centre; Jong, Rixt de [Lund Univ. (Sweden). Dept. of Quaternary Geology; Linderholm, Hans [Goeteborg Univ. (Sweden). Dept. of Earth Sciences; Zorita, Eduardo [GKSS Research Centre, Geesthacht (Germany)

    2006-12-15

    Knowledge about climatic variations is essential for SKB in its safety assessments of a geological repository for spent nuclear waste. There is therefore a need for information about possible future climatic variations under a range of possible climatic states. However, predictions of future climate in any deterministic sense are still beyond our reach. We can, nevertheless, try to estimate the magnitude of future climate variability and change due to natural forcing factors, by means of inferences drawn from natural climate variability in the past. Indeed, the climate of the future will be shaped by the sum of natural and anthropogenic climate forcing, as well as the internal climate variability. The aim here is to review and analyse the knowledge about Swedish climate variability, essentially during the past millennium. Available climate proxy data and long instrumental records provide empirical information on past climatic changes. We also demonstrate how climate modelling can be used to extend such knowledge. We use output from a global climate model driven with reconstructed radiative forcings (solar, volcanic and greenhouse gas forcing), to provide boundary conditions for a regional climate model. The regional model provides more details of the climate than the global model, and we develop a simulated climate history for Sweden that is complete in time and space and physically consistent. We use output from a regional model simulation for long periods in the last millennium, to study annual mean temperature, precipitation and runoff for the northern and southern parts of Sweden. The simulated data are used to place corresponding instrumental records for the 20th century into a plausible historical perspective. We also use output from the regional model to study how the frequency distribution of the daily temperature, precipitation, runoff and evaporation at Forsmark and Oskarshamn could have varied between unusually warm and cold 30-year periods during the

  6. Local impact analysis of climate change on precipitation extremes: are high-resolution climate models needed for realistic simulations?

    Science.gov (United States)

    Tabari, Hossein; De Troch, Rozemien; Giot, Olivier; Hamdi, Rafiq; Termonia, Piet; Saeed, Sajjad; Brisson, Erwan; Van Lipzig, Nicole; Willems, Patrick

    2016-09-01

    This study explores whether climate models with higher spatial resolutions provide higher accuracy for precipitation simulations and/or different climate change signals. The outputs from two convection-permitting climate models (ALARO and CCLM) with a spatial resolution of 3-4 km are compared with those from the coarse-scale driving models or reanalysis data for simulating/projecting daily and sub-daily precipitation quantiles. Validation of historical design precipitation statistics derived from intensity-duration-frequency (IDF) curves shows a better match of the convection-permitting model results with the observations-based IDF statistics compared to the driving GCMs and reanalysis data. This is the case for simulation of local sub-daily precipitation extremes during the summer season, while the convection-permitting models do not appear to bring added value to simulation of daily precipitation extremes. Results moreover indicate that one has to be careful in assuming spatial-scale independency of climate change signals for the delta change downscaling method, as high-resolution models may show larger changes in extreme precipitation. These larger changes appear to be dependent on the timescale, since such intensification is not observed for daily timescales for both the ALARO and CCLM models.

  7. Climate models and scenarios

    Energy Technology Data Exchange (ETDEWEB)

    Fortelius, C.; Holopainen, E.; Kaurola, J.; Ruosteenoja, K.; Raeisaenen, J. [Helsinki Univ. (Finland). Dept. of Meteorology

    1996-12-31

    In recent years the modelling of interannual climate variability has been studied, the atmospheric energy and water cycles, and climate simulations with the ECHAM3 model. In addition, the climate simulations of several models have been compared with special emphasis in the area of northern Europe

  8. The Impact of Different Absolute Solar Irradiance Values on Current Climate Model Simulations

    Science.gov (United States)

    Rind, David H.; Lean, Judith L.; Jonas, Jeffrey

    2014-01-01

    Simulations of the preindustrial and doubled CO2 climates are made with the GISS Global Climate Middle Atmosphere Model 3 using two different estimates of the absolute solar irradiance value: a higher value measured by solar radiometers in the 1990s and a lower value measured recently by the Solar Radiation and Climate Experiment. Each of the model simulations is adjusted to achieve global energy balance; without this adjustment the difference in irradiance produces a global temperature change of 0.48C, comparable to the cooling estimated for the Maunder Minimum. The results indicate that by altering cloud cover the model properly compensates for the different absolute solar irradiance values on a global level when simulating both preindustrial and doubled CO2 climates. On a regional level, the preindustrial climate simulations and the patterns of change with doubled CO2 concentrations are again remarkably similar, but there are some differences. Using a higher absolute solar irradiance value and the requisite cloud cover affects the model's depictions of high-latitude surface air temperature, sea level pressure, and stratospheric ozone, as well as tropical precipitation. In the climate change experiments it leads to an underestimation of North Atlantic warming, reduced precipitation in the tropical western Pacific, and smaller total ozone growth at high northern latitudes. Although significant, these differences are typically modest compared with the magnitude of the regional changes expected for doubled greenhouse gas concentrations. Nevertheless, the model simulations demonstrate that achieving the highest possible fidelity when simulating regional climate change requires that climate models use as input the most accurate (lower) solar irradiance value.

  9. A new model to simulate climate-change impacts on forest succession for local land management.

    Science.gov (United States)

    Yospin, Gabriel I; Bridgham, Scott D; Neilson, Ronald P; Bolte, John P; Bachelet, Dominique M; Gould, Peter J; Harrington, Constance A; Kertis, Jane A; Evers, Cody; Johnson, Bart R

    2015-01-01

    We developed a new climate-sensitive vegetation state-and-transition simulation model (CV-STSM) to simulate future vegetation at a fine spatial grain commensurate with the scales of human land-use decisions, and under the joint influences of changing climate, site productivity, and disturbance. CV-STSM integrates outputs from four different modeling systems. Successional changes in tree species composition and stand structure were represented as transition probabilities and organized into a state-and-transition simulation model. States were characterized based on assessments of both current vegetation and of projected future vegetation from a dynamic global vegetation model (DGVM). State definitions included sufficient detail to support the integration of CV-STSM with an agent-based model of land-use decisions and a mechanistic model of fire behavior and spread. Transition probabilities were parameterized using output from a stand biometric model run across a wide range of site productivities. Biogeographic and biogeochemical projections from the DGVM were used to adjust the transition probabilities to account for the impacts of climate change on site productivity and potential vegetation type. We conducted experimental simulations in the Willamette Valley, Oregon, USA. Our simulation landscape incorporated detailed new assessments of critically imperiled Oregon white oak (Quercus garryana) savanna and prairie habitats among the suite of existing and future vegetation types. The experimental design fully crossed four future climate scenarios with three disturbance scenarios. CV-STSM showed strong interactions between climate and disturbance scenarios. All disturbance scenarios increased the abundance of oak savanna habitat, but an interaction between the most intense disturbance and climate-change scenarios also increased the abundance of subtropical tree species. Even so, subtropical tree species were far less abundant at the end of simulations in CV-STSM than in

  10. Failure analysis of parameter-induced simulation crashes in climate models

    Directory of Open Access Journals (Sweden)

    D. D. Lucas

    2013-01-01

    Full Text Available Simulations using IPCC-class climate models are subject to fail or crash for a variety of reasons. Quantitative analysis of the failures can yield useful insights to better understand and improve the models. During the course of uncertainty quantification (UQ ensemble simulations to assess the effects of ocean model parameter uncertainties on climate simulations, we experienced a series of simulation crashes within the Parallel Ocean Program (POP2 component of the Community Climate System Model (CCSM4. About 8.5% of our CCSM4 simulations failed for numerical reasons at combinations of POP2 parameter values. We apply support vector machine (SVM classification from machine learning to quantify and predict the probability of failure as a function of the values of 18 POP2 parameters. A committee of SVM classifiers readily predicts model failures in an independent validation ensemble, as assessed by the area under the receiver operating characteristic (ROC curve metric (AUC > 0.96. The causes of the simulation failures are determined through a global sensitivity analysis. Combinations of 8 parameters related to ocean mixing and viscosity from three different POP2 parameterizations are the major sources of the failures. This information can be used to improve POP2 and CCSM4 by incorporating correlations across the relevant parameters. Our method can also be used to quantify, predict, and understand simulation crashes in other complex geoscientific models.

  11. Possible impact of climate change on meningitis in northwest Nigeria: an assessment using CMIP5 climate model simulations

    Science.gov (United States)

    Abdussalam, Auwal; Monaghan, Andrew; Steinhoff, Daniel; Dukic, Vanja; Hayden, Mary; Hopson, Thomas; Thornes, John; Leckebusch, Gregor

    2014-05-01

    Meningitis remains a major health burden throughout Sahelian Africa, especially in heavily-populated northwest Nigeria. Cases exhibit strong sensitivity to intra- and inter-annual climate variability, peaking during the hot and dry boreal spring months, raising concern that future climate change may increase the incidence of meningitis in the region. The impact of future climate change on meningitis risk in northwest Nigeria is assessed by forcing an empirical model of meningitis with monthly simulations from an ensemble of thirteen statistically downscaled global climate model projections from the Coupled Model Intercomparison Experiment Phase 5 (CMIP5) for RCPs 2.6, 6.0 and 8.5 scenarios. The results suggest future temperature increases due to climate change has the potential to significantly increase meningitis cases in both the early and late 21st century, and to increase the length of the meningitis season in the late century. March cases may increase from 23 per 100,000 people for present day (1990-2005), to 29-30 per 100,000 (p<0.01) in the early century (2020-2035) and 31-42 per 100,000 (p<0.01) in the late century (2060-2075), the range being dependent on the emissions scenario. It is noteworthy that these results represent the climatological potential for increased cases due to climate change, as we assume current prevention and treatment strategies remain similar in the future.

  12. The large influence of climate model bias on terrestrial carbon cycle simulations

    Science.gov (United States)

    Ahlström, Anders; Schurgers, Guy; Smith, Benjamin

    2017-01-01

    Global vegetation models and terrestrial carbon cycle models are widely used for projecting the carbon balance of terrestrial ecosystems. Ensembles of such models show a large spread in carbon balance predictions, ranging from a large uptake to a release of carbon by the terrestrial biosphere, constituting a large uncertainty in the associated feedback to atmospheric CO2 concentrations under global climate change. Errors and biases that may contribute to such uncertainty include ecosystem model structure, parameters and forcing by climate output from general circulation models (GCMs) or the atmospheric components of Earth system models (ESMs), e.g. as prepared for use in IPCC climate change assessments. The relative importance of these contributing factors to the overall uncertainty in carbon cycle projections is not well characterised. Here we investigate the role of climate model-derived biases by forcing a single global ecosystem-carbon cycle model, with original climate outputs from 15 ESMs and GCMs from the CMIP5 ensemble. We show that variation among the resulting ensemble of present and future carbon cycle simulations propagates from biases in annual means of temperature, precipitation and incoming shortwave radiation. Future changes in carbon pools, and thus land carbon sink trends, are also affected by climate biases, although to a smaller extent than the absolute size of carbon pools. Our results suggest that climate biases could be responsible for a considerable fraction of the large uncertainties in ESM simulations of land carbon fluxes and pools, amounting to about 40% of the range reported for ESMs. We conclude that climate bias-induced uncertainties must be decreased to make accurate coupled atmosphere-carbon cycle projections.

  13. Atmospheric Properties from the 2006 Niamey Deployment and Climate Simulation with a Geodesic Grid Coupled Climate Model Third Quarter 2008

    Energy Technology Data Exchange (ETDEWEB)

    JH Mather; DA Randall; CJ Flynn

    2008-06-30

    In 2008, the Atmospheric Radiation Measurement (ARM) Program and the Climate Change Prediction Program (CCPP) have been asked to produce joint science metrics. For CCPP, the metrics will deal with a decade-long control simulation using geodesic grid-coupled climate model. For ARM, the metrics will deal with observations associated with the 2006 deployment of the ARM Mobile Facility (AMF) to Niamey, Niger. Specifically, ARM has been asked to deliver data products for Niamey that describe cloud, aerosol, and dust properties. This report describes the aerosol optical depth (AOD) product.

  14. Conditional statistical models: a discourse about the local scale in climate simulations

    Energy Technology Data Exchange (ETDEWEB)

    Storch, H. von [GKSS-Forschungszentrum Geesthacht GmbH (Germany). Inst. fuer Hydrophysik

    1997-12-31

    The local scale of climate plays two different roles; it is the scale at which people experience climate, so that it is the dominant scale of applied climate research, ranging from climate impact to forecasting weather in the atmosphere and the ocean. On the other hand, the local scale is not important in its details for the formation of the global climate. For the understanding, and simulation, of the global climate, the small scales matter only in a statistical sense so that their influence may be described by means of parameterizations. In the present essay, we demonstrate that both processes, `downscaling` (the derivation of local information in climate change and climate variability simulations and in weather forecasts) and `parametrization` (the description of the net effect of small scales on the larger scales) may formally be understood as the building of empirical models whose parameters are conditioned upon larger-scale features of the state of the atmosphere or ocean. It is suggested to acknowledge the presence of unknown processes by building downscaling and parameterization procedures with a randomized design, conditioned upon the known resolved scales. (orig.)

  15. Improving plot- and regional-scale crop models for simulating impacts of climate variability and extremes

    Science.gov (United States)

    Tao, F.; Rötter, R.

    2013-12-01

    Many studies on global climate report that climate variability is increasing with more frequent and intense extreme events1. There are quite large uncertainties from both the plot- and regional-scale models in simulating impacts of climate variability and extremes on crop development, growth and productivity2,3. One key to reducing the uncertainties is better exploitation of experimental data to eliminate crop model deficiencies and develop better algorithms that more adequately capture the impacts of extreme events, such as high temperature and drought, on crop performance4,5. In the present study, in a first step, the inter-annual variability in wheat yield and climate from 1971 to 2012 in Finland was investigated. Using statistical approaches the impacts of climate variability and extremes on wheat growth and productivity were quantified. In a second step, a plot-scale model, WOFOST6, and a regional-scale crop model, MCWLA7, were calibrated and validated, and applied to simulate wheat growth and yield variability from 1971-2012. Next, the estimated impacts of high temperature stress, cold damage, and drought stress on crop growth and productivity based on the statistical approaches, and on crop simulation models WOFOST and MCWLA were compared. Then, the impact mechanisms of climate extremes on crop growth and productivity in the WOFOST model and MCWLA model were identified, and subsequently, the various algorithm and impact functions were fitted against the long-term crop trial data. Finally, the impact mechanisms, algorithms and functions in WOFOST model and MCWLA model were improved to better simulate the impacts of climate variability and extremes, particularly high temperature stress, cold damage and drought stress for location-specific and large area climate impact assessments. Our studies provide a good example of how to improve, in parallel, the plot- and regional-scale models for simulating impacts of climate variability and extremes, as needed for

  16. The simulation of cutoff lows in a regional climate model: reliability and future trends

    Energy Technology Data Exchange (ETDEWEB)

    Grose, Michael R. [University of Tasmania, Antarctic Climate and Ecosystems Cooperative Research Centre (ACE CRC), Private Bag 80, Hobart, TAS (Australia); Pook, Michael J.; McIntosh, Peter C.; Risbey, James S. [CSIRO Marine and Atmospheric Research, Centre for Australian Weather and Climate Research (CAWCR), Hobart, TAS (Australia); Bindoff, Nathaniel L. [University of Tasmania, Antarctic Climate and Ecosystems Cooperative Research Centre (ACE CRC), Private Bag 80, Hobart, TAS (Australia); CSIRO Marine and Atmospheric Research, Centre for Australian Weather and Climate Research (CAWCR), Hobart, TAS (Australia); University of Tasmania, Institute of Marine and Antarctic Studies (IMAS), Private Bag 129, Hobart, TAS (Australia)

    2012-07-15

    Cutoff lows are an important source of rainfall in the mid-latitudes that climate models need to simulate accurately to give confidence in climate projections for rainfall. Coarse-scale general circulation models used for climate studies show some notable biases and deficiencies in the simulation of cutoff lows in the Australian region and important aspects of the broader circulation such as atmospheric blocking and the split jet structure observed over Australia. The regional climate model conformal cubic atmospheric model or CCAM gives an improvement in some aspects of the simulation of cutoffs in the Australian region, including a reduction in the underestimate of the frequency of cutoff days by more than 15 % compared to a typical GCM. This improvement is due at least in part to substantially higher resolution. However, biases in the simulation of the broader circulation, blocking and the split jet structure are still present. In particular, a northward bias in the central latitude of cutoff lows creates a substantial underestimate of the associated rainfall over Tasmania in April to October. Also, the regional climate model produces a significant north-south distortion of the vertical profile of cutoff lows, with the largest distortion occurring in the cooler months that was not apparent in GCM simulations. The remaining biases and presence of new biases demonstrates that increased horizontal resolution is not the only requirement in the reliable simulation of cutoff lows in climate models. Notwithstanding the biases in their simulation, the regional climate model projections show some responses to climate warming that are noteworthy. The projections indicate a marked closing of the split jet in winter. This change is associated with changes to atmospheric blocking in the Tasman Sea, which decreases in June to November (by up to 7.9 m s{sup -1}), and increases in December to May. The projections also show a reduction in the number of annual cutoff days by 67

  17. On the Ability of the Regional Climate Model RIEMS to Simulate the Present Climate over Asia

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    A continuous 10-year simulation in Asia for the period of 1 July 1988 to 31 December 1998 was conducted using the Regional Integrated Environmental Model System (RIEMS) with NCEP Reanalysis Ⅱ data as the driving fields. The model processes include surface physics state package (BATS le), a Holtslag explicit planetary boundary layer formulation, a Grell cumulus parameterization, and a modified radiation package (CCM3). Model-produced surface temperature and precipitation are compared with observations from 1001 meteorology stations distributed over Asia and with the 0.5°× 0.5° CRU gridded dataset. The analysis results show that: (1) RIEMS reproduces well the spatial pattern and the seasonal cycle of surface temperature and precipitation; (2) When regionally averaged, the seasonal mean temperature biases are within 1-2°C. For precipitation, the model tends to give better simulation in winter than in summer,and seasonal precipitation biases are mostly in the range of -12%-50%; (3) Spatial correlation coefficients between observed and simulated seasonal precipitation are higher in north of the Yangtze River than in the south and higher in winter than in summer; (4) RIEMS can well reproduce the spatial pattern of seasonal mean sea level pressure. In winter, the model-simulated Siberian high is stronger than the observed. In summer, the simulated subtropical high is shifted northwestwards; (5) The temporal evolution of the East Asia summer monsoon rain belt, with steady phases separated by more rapid transitions, is reproduced.

  18. High resolution global climate modelling; the UPSCALE project, a large simulation campaign

    Directory of Open Access Journals (Sweden)

    M. S. Mizielinski

    2014-01-01

    Full Text Available The UPSCALE (UK on PRACE: weather-resolving Simulations of Climate for globAL Environmental risk project constructed and ran an ensemble of HadGEM3 (Hadley centre Global Environment Model 3 atmosphere-only global climate simulations over the period 1985–2011, at resolutions of N512 (25 km, N216 (60 km and N96 (130 km as used in current global weather forecasting, seasonal prediction and climate modelling respectively. Alongside these present climate simulations a parallel ensemble looking at extremes of future climate was run, using a time-slice methodology to consider conditions at the end of this century. These simulations were primarily performed using a 144 million core hour, single year grant of computing time from PRACE (the Partnership for Advanced Computing in Europe in 2012, with additional resources supplied by the Natural Environmental Research Council (NERC and the Met Office. Almost 400 terabytes of simulation data were generated on the HERMIT supercomputer at the high performance computing center Stuttgart (HLRS, and transferred to the JASMIN super-data cluster provided by the Science and Technology Facilities Council Centre for Data Archival (STFC CEDA for analysis and storage. In this paper we describe the implementation of the project, present the technical challenges in terms of optimisation, data output, transfer and storage that such a project involves and include details of the model configuration and the composition of the UPSCALE dataset. This dataset is available for scientific analysis to allow assessment of the value of model resolution in both present and potential future climate conditions.

  19. High-resolution global climate modelling: the UPSCALE project, a large-simulation campaign

    Directory of Open Access Journals (Sweden)

    M. S. Mizielinski

    2014-08-01

    Full Text Available The UPSCALE (UK on PRACE: weather-resolving Simulations of Climate for globAL Environmental risk project constructed and ran an ensemble of HadGEM3 (Hadley Centre Global Environment Model 3 atmosphere-only global climate simulations over the period 1985–2011, at resolutions of N512 (25 km, N216 (60 km and N96 (130 km as used in current global weather forecasting, seasonal prediction and climate modelling respectively. Alongside these present climate simulations a parallel ensemble looking at extremes of future climate was run, using a time-slice methodology to consider conditions at the end of this century. These simulations were primarily performed using a 144 million core hour, single year grant of computing time from PRACE (the Partnership for Advanced Computing in Europe in 2012, with additional resources supplied by the Natural Environment Research Council (NERC and the Met Office. Almost 400 terabytes of simulation data were generated on the HERMIT supercomputer at the High Performance Computing Center Stuttgart (HLRS, and transferred to the JASMIN super-data cluster provided by the Science and Technology Facilities Council Centre for Data Archival (STFC CEDA for analysis and storage. In this paper we describe the implementation of the project, present the technical challenges in terms of optimisation, data output, transfer and storage that such a project involves and include details of the model configuration and the composition of the UPSCALE data set. This data set is available for scientific analysis to allow assessment of the value of model resolution in both present and potential future climate conditions.

  20. Sensitivity of simulated regional Arctic climate to the choice of coupled model domain

    Directory of Open Access Journals (Sweden)

    Dmitry V. Sein

    2014-07-01

    Full Text Available The climate over the Arctic has undergone changes in recent decades. In order to evaluate the coupled response of the Arctic system to external and internal forcing, our study focuses on the estimation of regional climate variability and its dependence on large-scale atmospheric and regional ocean circulations. A global ocean–sea ice model with regionally high horizontal resolution is coupled to an atmospheric regional model and global terrestrial hydrology model. This way of coupling divides the global ocean model setup into two different domains: one coupled, where the ocean and the atmosphere are interacting, and one uncoupled, where the ocean model is driven by prescribed atmospheric forcing and runs in a so-called stand-alone mode. Therefore, selecting a specific area for the regional atmosphere implies that the ocean–atmosphere system can develop ‘freely’ in that area, whereas for the rest of the global ocean, the circulation is driven by prescribed atmospheric forcing without any feedbacks. Five different coupled setups are chosen for ensemble simulations. The choice of the coupled domains was done to estimate the influences of the Subtropical Atlantic, Eurasian and North Pacific regions on northern North Atlantic and Arctic climate. Our simulations show that the regional coupled ocean–atmosphere model is sensitive to the choice of the modelled area. The different model configurations reproduce differently both the mean climate and its variability. Only two out of five model setups were able to reproduce the Arctic climate as observed under recent climate conditions (ERA-40 Reanalysis. Evidence is found that the main source of uncertainty for Arctic climate variability and its predictability is the North Pacific. The prescription of North Pacific conditions in the regional model leads to significant correlation with observations, even if the whole North Atlantic is within the coupled model domain. However, the inclusion of the

  1. Simulating the link between ENSO and summer drought in Southern Africa using regional climate models

    Science.gov (United States)

    Meque, Arlindo; Abiodun, Babatunde J.

    2015-04-01

    This study evaluates the capability of regional climate models (RCMs) in simulating the link between El Niño Southern Oscillation (ENSO) and Southern African droughts. It uses the Standardized Precipitation-Evapotranspiration Index (SPEI, computed using rainfall and temperature data) to identify 3-month drought over Southern Africa, and compares the observed and simulated correlation between ENSO and SPEI. The observation data are from the Climate Research Unit, while the simulation data are from ten RCMs (ARPEGE, CCLM, HIRHAM, RACMO, REMO, PRECIS, RegCM3, RCA, WRF, and CRCM) that participated in the regional climate downscaling experiment (CORDEX) project. The study analysed the rainy season (December-February) data for 19 years (1989-2008). The results show a strong link between ENSO and droughts (SPEI) over Southern Africa. The link is owing to the influence of ENSO on both rainfall and temperature fields, but the correlation between ENSO and temperature is stronger than the correlation between ENSO and rainfall. Hence, using only rainfall to monitor droughts in Southern Africa may underestimate the influence of ENSO on the droughts. Only few CORDEX RCMs simulate the influence of ENSO on Southern African drought as observed. In this regard, the ARPEGE model shows the best simulation, while CRCM shows the worst. The different in the performance may be due to their lateral boundary conditions. The RCA-simulated link between ENSO and Southern African droughts is sensitive to the global dataset used as the lateral boundary conditions. In some cases, using RCA to downscale global circulation models (GCM) simulations adds value to the simulated link between ENSO and the droughts, but in other cases the downscaling adds no value to the link. The added value of RCA to the simulated link decreases as the capability of the GCM to simulate the link increases. This study suggests that downscaling GCM simulations with RCMs over Southern Africa may improve or depreciate the

  2. Simulation by CMIP5 models of the atlantic multidecadal oscillation and its climate impacts

    Science.gov (United States)

    Han, Zhe; Luo, Feifei; Li, Shuanglin; Gao, Yongqi; Furevik, Tore; Svendsen, Lea

    2016-12-01

    This study focuses on the climatic impacts of the Atlantic Multidecadal Oscillation (AMO) as a mode of internal variability. Given the difficulties involved in excluding the effects of external forcing from internal variation, i.e., owing to the short record length of instrumental observations and historical simulations, we assess and compare the AMO and its related climatic impacts both in observations and in the "Pre-industrial" experiments of models participating in CMIP5. First, we evaluate the skill of the 25 CMIP5 models' "Historical" simulations in simulating the observational AMO, and find there is generally a considerable range of skill among them in this regard. Six of the models with higher skill relative to the other models are selected to investigate the AMO-related climate impacts, and it is found that their "Pre-industrial" simulations capture the essential features of the AMO. A positive AMO favors warmer surface temperature around the North Atlantic, and the Atlantic ITCZ shifts northward leading to more rainfall in the Sahel and less rainfall in Brazil. Furthermore, the results confirm the existence of a teleconnection between the AMO and East Asian surface temperature, as well as the late withdrawal of the Indian summer monsoon, during positive AMO phases. These connections could be mainly caused by internal climate variability. Opposite patterns are true for the negative phase of the AMO.

  3. Coupled Model Intercomparison Project 5 (CMIP5) simulations of climate following volcanic eruptions

    KAUST Repository

    Driscoll, Simon

    2012-09-16

    The ability of the climate models submitted to the Coupled Model Intercomparison Project 5 (CMIP5) database to simulate the Northern Hemisphere winter climate following a large tropical volcanic eruption is assessed. When sulfate aerosols are produced by volcanic injections into the tropical stratosphere and spread by the stratospheric circulation, it not only causes globally averaged tropospheric cooling but also a localized heating in the lower stratosphere, which can cause major dynamical feedbacks. Observations show a lower stratospheric and surface response during the following one or two Northern Hemisphere (NH) winters, that resembles the positive phase of the North Atlantic Oscillation (NAO). Simulations from 13 CMIP5 models that represent tropical eruptions in the 19th and 20th century are examined, focusing on the large-scale regional impacts associated with the large-scale circulation during the NH winter season. The models generally fail to capture the NH dynamical response following eruptions. They do not sufficiently simulate the observed post-volcanic strengthened NH polar vortex, positive NAO, or NH Eurasian warming pattern, and they tend to overestimate the cooling in the tropical troposphere. The findings are confirmed by a superposed epoch analysis of the NAO index for each model. The study confirms previous similar evaluations and raises concern for the ability of current climate models to simulate the response of a major mode of global circulation variability to external forcings. This is also of concern for the accuracy of geoengineering modeling studies that assess the atmospheric response to stratosphere-injected particles.

  4. Simulation skill of APCC set of global climate models for Asian summer monsoon rainfall variability

    Science.gov (United States)

    Singh, U. K.; Singh, G. P.; Singh, Vikas

    2015-04-01

    The performance of 11 Asia-Pacific Economic Cooperation Climate Center (APCC) global climate models (coupled and uncoupled both) in simulating the seasonal summer (June-August) monsoon rainfall variability over Asia (especially over India and East Asia) has been evaluated in detail using hind-cast data (3 months advance) generated from APCC which provides the regional climate information product services based on multi-model ensemble dynamical seasonal prediction systems. The skill of each global climate model over Asia was tested separately in detail for the period of 21 years (1983-2003), and simulated Asian summer monsoon rainfall (ASMR) has been verified using various statistical measures for Indian and East Asian land masses separately. The analysis found a large variation in spatial ASMR simulated with uncoupled model compared to coupled models (like Predictive Ocean Atmosphere Model for Australia, National Centers for Environmental Prediction and Japan Meteorological Agency). The simulated ASMR in coupled model was closer to Climate Prediction Centre Merged Analysis of Precipitation (CMAP) compared to uncoupled models although the amount of ASMR was underestimated in both models. Analysis also found a high spread in simulated ASMR among the ensemble members (suggesting that the model's performance is highly dependent on its initial conditions). The correlation analysis between sea surface temperature (SST) and ASMR shows that that the coupled models are strongly associated with ASMR compared to the uncoupled models (suggesting that air-sea interaction is well cared in coupled models). The analysis of rainfall using various statistical measures suggests that the multi-model ensemble (MME) performed better compared to individual model and also separate study indicate that Indian and East Asian land masses are more useful compared to Asia monsoon rainfall as a whole. The results of various statistical measures like skill of multi-model ensemble, large spread

  5. Biases in simulation of the rice phenology models when applied in warmer climates

    Science.gov (United States)

    Zhang, T.; Li, T.; Yang, X.; Simelton, E.

    2015-12-01

    The current model inter-comparison studies highlight the difference in projections between crop models when they are applied to warmer climates, but these studies do not provide results on how the accuracy of the models would change in these projections because the adequate observations under largely diverse growing season temperature (GST) are often unavailable. Here, we investigate the potential changes in the accuracy of rice phenology models when these models were applied to a significantly warmer climate. We collected phenology data from 775 trials with 19 cultivars in 5 Asian countries (China, India, Philippines, Bangladesh and Thailand). Each cultivar encompasses the phenology observations under diverse GST regimes. For a given rice cultivar in different trials, the GST difference reaches 2.2 to 8.2°C, which allows us to calibrate the models under lower GST and validate under higher GST (i.e., warmer climates). Four common phenology models representing major algorithms on simulations of rice phenology, and three model calibration experiments were conducted. The results suggest that the bilinear and beta models resulted in gradually increasing phenology bias (Figure) and double yield bias per percent increase in phenology bias, whereas the growing-degree-day (GDD) and exponential models maintained a comparatively constant bias when applied in warmer climates (Figure). Moreover, the bias of phenology estimated by the bilinear and beta models did not reduce with increase in GST when all data were used to calibrate models. These suggest that variations in phenology bias are primarily attributed to intrinsic properties of the respective phenology model rather than on the calibration dataset. Therefore we conclude that using the GDD and exponential models has more chances of predicting rice phenology correctly and thus, production under warmer climates, and result in effective agricultural strategic adaptation to and mitigation of climate change.

  6. How well do integrated assessment models simulate climate change?

    NARCIS (Netherlands)

    van Vuuren, D.P.; Lowe, J.; Stehfest, E.; Gohar, L.; Hof, Andries; Hope, C.; Warren, R.; Meinshausen, M.; Plattner, G.K.

    2011-01-01

    Integrated assessment models (IAMs) are regularly used to evaluate different policies of future emissions reductions. Since the global costs associated with these policies are immense, it is vital that the uncertainties in IAMs are quantified and understood. We first demonstrate the significant spre

  7. First Evaluation of the CCAM Aerosol Simulation over Africa: Implications for Regional Climate Modeling

    Science.gov (United States)

    Horowitz, H.; Garland, R. M.; Thatcher, M. J.; Naidoo, M.; van der Merwe, J.; Landman, W.; Engelbrecht, F.

    2015-12-01

    An accurate representation of African aerosols in climate models is needed to understand the regional and global radiative forcing and climate impacts of aerosols, at present and under future climate change. However, aerosol simulations in regional climate models for Africa have not been well-tested. Africa contains the largest single source of biomass-burning smoke aerosols and dust globally. Although aerosols are short-lived relative to greenhouse gases, black carbon in particular is estimated to be second only to carbon dioxide in contributing to warming on a global scale. Moreover, Saharan dust is exported great distances over the Atlantic Ocean, affecting nutrient transport to regions like the Amazon rainforest, which can further impact climate. Biomass burning aerosols are also exported from Africa, westward from Angola over the Atlantic Ocean and off the southeastern coast of South Africa to the Indian Ocean. Here, we perform the first extensive quantitative evaluation of the Conformal-Cubic Atmospheric Model (CCAM) aerosol simulation against monitored data, focusing on aerosol optical depth (AOD) observations over Africa. We analyze historical regional simulations for 1999 - 2012 from CCAM consistent with the experimental design of CORDEX at 50 km global horizontal resolution, through the dynamical downscaling of ERA-Interim data reanalysis data, with the CMIP5 emissions inventory (RCP8.5 scenario). CCAM has a prognostic aerosol scheme for organic carbon, black carbon, sulfate, and dust, and non-prognostic sea salt. The CCAM AOD at 550nm was compared to AOD (observed at 440nm, adjusted to 550nm with the Ångström exponent) from long-term AERONET stations across Africa. Sites strongly impacted by dust and biomass burning and with long continuous records were prioritized. In general, the model captures the monthly trends of the AERONET data. This presentation provides a basis for understanding how well aerosol particles are represented over Africa in

  8. Climatic and economic parameters of the grape-wine simulation model

    Directory of Open Access Journals (Sweden)

    Károly Szenteleki

    2011-11-01

    Full Text Available The reliability of grape-wine product line models is depending mainly on the accuracy of the parameter estimations based on experts’ opinion. However, model parameter estimations can be based also on newly developed climatic data bases as well as other information systems concerning product lines. In this study we introduce a grape-wine simulation product line model with a new data base system of climatic parameters organized spatially for grape growing sites. The presented development plan makes a proposal for creating and maintaining an “Integrated Information System in the Grape-Wine Sector” (VINNET that enables an easier, more effective and more cost efficient collective platform leaning on the current systems. The system can serve a more accurate estimation of economic parameters that are necessary for simulation modelling.

  9. Simulation of the present-day climate with the climate model INMCM5

    Science.gov (United States)

    Volodin, E. M.; Mortikov, E. V.; Kostrykin, S. V.; Galin, V. Ya.; Lykossov, V. N.; Gritsun, A. S.; Diansky, N. A.; Gusev, A. V.; Iakovlev, N. G.

    2017-02-01

    In this paper we present the fifth generation of the INMCM climate model that is being developed at the Institute of Numerical Mathematics of the Russian Academy of Sciences (INMCM5). The most important changes with respect to the previous version (INMCM4) were made in the atmospheric component of the model. Its vertical resolution was increased to resolve the upper stratosphere and the lower mesosphere. A more sophisticated parameterization of condensation and cloudiness formation was introduced as well. An aerosol module was incorporated into the model. The upgraded oceanic component has a modified dynamical core optimized for better implementation on parallel computers and has two times higher resolution in both horizontal directions. Analysis of the present-day climatology of the INMCM5 (based on the data of historical run for 1979-2005) shows moderate improvements in reproduction of basic circulation characteristics with respect to the previous version. Biases in the near-surface temperature and precipitation are slightly reduced compared with INMCM4 as well as biases in oceanic temperature, salinity and sea surface height. The most notable improvement over INMCM4 is the capability of the new model to reproduce the equatorial stratospheric quasi-biannual oscillation and statistics of sudden stratospheric warmings.

  10. High Resolution Simulations of Future Climate in West Africa Using a Variable-Resolution Atmospheric Model

    Science.gov (United States)

    Adegoke, J. O.; Engelbrecht, F.; Vezhapparambu, S.

    2013-12-01

    In previous work demonstrated the application of a var¬iable-resolution global atmospheric model, the conformal-cubic atmospheric model (CCAM), across a wide range of spatial and time scales to investigate the ability of the model to provide realistic simulations of present-day climate and plausible projections of future climate change over sub-Saharan Africa. By applying the model in stretched-grid mode the versatility of the model dynamics, numerical formulation and physical parameterizations to function across a range of length scales over the region of interest, was also explored. We primarily used CCAM to illustrate the capability of the model to function as a flexible downscaling tool at the climate-change time scale. Here we report on additional long term climate projection studies performed by downscaling at much higher resolutions (8 Km) over an area that stretches from just south of Sahara desert to the southern coast of the Niger Delta and into the Gulf of Guinea. To perform these simulations, CCAM was provided with synoptic-scale forcing of atmospheric circulation from 2.5 deg resolution NCEP reanalysis at 6-hourly interval and SSTs from NCEP reanalysis data uses as lower boundary forcing. CCAM 60 Km resolution downscaled to 8 Km (Schmidt factor 24.75) then 8 Km resolution simulation downscaled to 1 Km (Schmidt factor 200) over an area approximately 50 Km x 50 Km in the southern Lake Chad Basin (LCB). Our intent in conducting these high resolution model runs was to obtain a deeper understanding of linkages between the projected future climate and the hydrological processes that control the surface water regime in this part of sub-Saharan Africa.

  11. Testing empirical relationships between global sea-level and global temperature in long climate model simulations

    Science.gov (United States)

    von Storch, H.; Zorita, E.; Gonzalez-Rouco, F.

    2009-04-01

    Estimations of future global sea-level rise brought about by increasing concentrations of atmospheric greenhouse gases of anthropogenic origin are based on simulations with coarse-resolution global climate models, which imposes some limitations on the skill of future projections because some of the processes that modulate the heat and fresh water flux into may not be adequately represented. To fill this gap, and until more complex climate models are available, some ad-hoc methods have been proposed that link the rise in global average temperature with the global mean sea-level rise. The statistical methods can be calibrated with observations and applied to the future global temperature rise simulated by climate models. This methods can be tested in the virtual reality simulated by global atmosphere.ocean models. Thereby, deficiencies can be identified and improvement suggested. The output of 1000-year long climate model simulation with the coupled atmosphere-ocean model ECHO-G over the past millennium has been used to determine the skill of different predictors to describe the variations of the rate of sea-level change in the simulation. These predictor variables comprise the global mean near-surface temperature, its rate of change with time and the heat-flux into the ocean. It is found that, in the framework of this climate simulation, global mean temperature is not a good predictor for the rate-of-change of sea-level. The correlation between both variables is not stable along the simulations and even its sign changes. A better predictor is the rate-of-change of temperature. Its correlation with the rate-of-change of sea-level is much more stable, it is always positive along the simulation, and there exists a lead-lag relationship between both that can be understood in simple physical terms. The best predictor among those tested is the heat-flux into the ocean. Its correlation is higher and there exists no time lag to the rate-of-change of sea-level, as expected

  12. Bias correction methods for regional climate model simulations considering the distributional parametric uncertainty underlying the observations

    Science.gov (United States)

    Kim, Kue Bum; Kwon, Hyun-Han; Han, Dawei

    2015-11-01

    In this paper, we present a comparative study of bias correction methods for regional climate model simulations considering the distributional parametric uncertainty underlying the observations/models. In traditional bias correction schemes, the statistics of the simulated model outputs are adjusted to those of the observation data. However, the model output and the observation data are only one case (i.e., realization) out of many possibilities, rather than being sampled from the entire population of a certain distribution due to internal climate variability. This issue has not been considered in the bias correction schemes of the existing climate change studies. Here, three approaches are employed to explore this issue, with the intention of providing a practical tool for bias correction of daily rainfall for use in hydrologic models ((1) conventional method, (2) non-informative Bayesian method, and (3) informative Bayesian method using a Weather Generator (WG) data). The results show some plausible uncertainty ranges of precipitation after correcting for the bias of RCM precipitation. The informative Bayesian approach shows a narrower uncertainty range by approximately 25-45% than the non-informative Bayesian method after bias correction for the baseline period. This indicates that the prior distribution derived from WG may assist in reducing the uncertainty associated with parameters. The implications of our results are of great importance in hydrological impact assessments of climate change because they are related to actions for mitigation and adaptation to climate change. Since this is a proof of concept study that mainly illustrates the logic of the analysis for uncertainty-based bias correction, future research exploring the impacts of uncertainty on climate impact assessments and how to utilize uncertainty while planning mitigation and adaptation strategies is still needed.

  13. Regionalizing global climate models

    NARCIS (Netherlands)

    Pitman, A.J.; Arneth, A.; Ganzeveld, L.N.

    2012-01-01

    Global climate models simulate the Earth's climate impressively at scales of continents and greater. At these scales, large-scale dynamics and physics largely define the climate. At spatial scales relevant to policy makers, and to impacts and adaptation, many other processes may affect regional and

  14. Characteristics of rainfall events in regional climate model simulations for the Czech Republic

    Science.gov (United States)

    Svoboda, Vojtěch; Hanel, Martin; Máca, Petr; Kyselý, Jan

    2017-02-01

    Characteristics of rainfall events in an ensemble of 23 regional climate model (RCM) simulations are evaluated against observed data in the Czech Republic for the period 1981-2000. Individual rainfall events are identified using the concept of minimum inter-event time (MIT) and only heavy events (15 % of events with the largest event depths) during the warm season (May-September) are considered. Inasmuch as an RCM grid box represents a spatial average, the effects of areal averaging of rainfall data on characteristics of events are investigated using the observed data. Rainfall events from the RCM simulations are then compared to those from the at-site and area-average observations. Simulated number of heavy events and seasonal total precipitation due to heavy events are on average represented relatively well despite the higher spatial variation compared to observations. RCM-simulated event depths are comparable to the area-average observations, while event durations are overestimated and other characteristics related to rainfall intensity are significantly underestimated. The differences between RCM-simulated and at-site observed rainfall event characteristics are in general dominated by the biases of the climate models rather than the areal-averaging effect. Most of the rainfall event characteristics in the majority of the RCM simulations show a similar altitude-dependence pattern as in the observed data. The number of heavy events and seasonal total precipitation due to heavy events increase with altitude, and this dependence is captured better by the RCM simulations with higher spatial resolution.

  15. An improved lake model for climate simulations: Model structure, evaluation, and sensitivity analyses in CESM1

    Directory of Open Access Journals (Sweden)

    Zachary Subin

    2012-02-01

    Full Text Available Lakes can influence regional climate, yet most general circulation models have, at best, simple and largely untested representations of lakes. We developed the Lake, Ice, Snow, and Sediment Simulator(LISSS for inclusion in the land-surface component (CLM4 of an earth system model (CESM1. The existing CLM4 lake modelperformed poorly at all sites tested; for temperate lakes, summer surface water temperature predictions were 10–25uC lower than observations. CLM4-LISSS modifies the existing model by including (1 a treatment of snow; (2 freezing, melting, and ice physics; (3 a sediment thermal submodel; (4 spatially variable prescribed lakedepth; (5 improved parameterizations of lake surface properties; (6 increased mixing under ice and in deep lakes; and (7 correction of previous errors. We evaluated the lake model predictions of water temperature and surface fluxes at three small temperate and boreal lakes where extensive observational data was available. We alsoevaluated the predicted water temperature and/or ice and snow thicknesses for ten other lakes where less comprehensive forcing observations were available. CLM4-LISSS performed very well compared to observations for shallow to medium-depth small lakes. For large, deep lakes, the under-prediction of mixing was improved by increasing the lake eddy diffusivity by a factor of 10, consistent with previouspublished analyses. Surface temperature and surface flux predictions were improved when the aerodynamic roughness lengths were calculated as a function of friction velocity, rather than using a constant value of 1 mm or greater. We evaluated the sensitivity of surface energy fluxes to modeled lake processes and parameters. Largechanges in monthly-averaged surface fluxes (up to 30 W m22 were found when excluding snow insulation or phase change physics and when varying the opacity, depth, albedo of melting lake ice, and mixing strength across ranges commonly found in real lakes. Typical

  16. Evaluation of a regional climate model for atmospheric simulation over Arctic river basins

    Institute of Scientific and Technical Information of China (English)

    MA Yan; CHEN Shang; HUA Feng; WEI Helin; D. H. BROMWICH

    2008-01-01

    Evaluation on a regional climate model was made with five-month atmospheric simulations over the Arctic river basins. The simulations were performed with a modified mesoscale model, Polar MM5 coupled to the NCAR Land Surface Model (LSM) to illustrate the skill of the coupled model (Polar MM5+LSM) in simulating atmospheric circulation over the Arctic river basins. Near-surface and upper-air observations were used to verify the simulations. Sensitivity studies between the Polar MM5 and Polar MMS+LSM simulations revealed that the coupled model could improve the forecast skill for surface variables at some sites. In addition, the extended evaluations of the coupled model simulations on the North American Arctic domain during December 15, 2002 to May 15, 2003 were carded out. The time series plots and statistics of the observations and Polar MM5+LSM simulations at six stations for near-surface and vertical profiles at 850 hPa and 500 hPa were analyzed. The model was found capable of reproducing the observed atmospheric behavior in both magnitude and variability, especially for temperature and near-surface wind direction.

  17. Using a Coupled Lake Model with WRF to Improve High-Resolution Regional Climate Simulations

    Science.gov (United States)

    Mallard, M.; Bullock, R.; Nolte, C. G.; Alapaty, K.; Otte, T.; Gula, J.

    2012-12-01

    Lakes can play a significant role in regional climate by modifying air masses through fluxes of heat and moisture and by modulating inland extremes in temperature. Representing these effects becomes more important as regional climate modeling efforts employ finer grid spacing in order to simulate smaller scales. The Weather Research and Forecasting (WRF) model does not simulate lakes explicitly. Instead, lake points are treated as ocean points, with sea surface temperatures (SSTs) interpolated from the nearest neighboring ocean point in the driving coarse-scale fields. This can result in substantial errors for inland lakes such as the Great Lakes. Although prescribed lake surface temperatures (LSTs) can be used for retrospective modeling applications, this may not be desirable for applications involving downscaling future climate scenarios from a global climate model (GCM). In such downscaling simulations, lakes that impact the regional climate in the area of interest may not be resolved by the coarser global input fields. Explicitly simulating the LST would allow WRF to better represent interannual variability in regions significantly affected by lakes, and the influence of such variability on temperature and precipitation patterns. Therefore, coupling a lake model to WRF may lead to more reliable assessments of the impacts of extreme events on human health and the environment. We employ a version of WRF coupled to the Freshwater Lake model, FLake (Gula and Peltier 2012). FLake is a 1D bulk lake model which provides updated LSTs and ice coverage throughout the integration. This two-layer model uses a temperature-depth profile which includes a homogeneous mixed layer at the surface and a thermocline below. The shape of the thermocline is assumed, based on past theoretical and observational studies. Therefore, additional variables required for FLake to run are minimal, and it does not require tuning for individual lakes. These characteristics are advantageous for a

  18. Atmospheric Properties from the 2006 Niamey Deployment and Climate Simulation with a Geodesic Grid Coupled Climate Model Fourth Quarter 2008

    Energy Technology Data Exchange (ETDEWEB)

    JH Mather; DA Randall; CJ Flynn

    2008-09-30

    In 2008, the Atmospheric Radiation Measurement (ARM) Program and the Climate Change Prediction Program (CCPP) have been asked to produce joint science metrics. For CCPP, the metrics will deal with a decade-long control simulation using geodesic grid-coupled climate model. For ARM, the metrics will deal with observations associated with the 2006 deployment of the ARM Mobile Facility (AMF) to Niamey, Niger. Specifically, ARM has been asked to deliver data products for Niamey that describe cloud, aerosol, and dust properties. The first quarter milestone was the initial formulation of the algorithm for retrieval of these properties. The second quarter milestone included the time series of ARM-retrieved cloud properties and a year-long CCPP control simulation. The third quarter milestone included the time series of ARM-retrieved aerosol optical depth and a three-year CCPP control simulation. This final fourth quarter milestone includes the time-series of aerosol and dust properties and a decade-long CCPP control simulation.

  19. Assessment Of The Impact Of ESA CCI Land Cover Information For Global Climate Model Simulations

    Science.gov (United States)

    Khlystova, Iryna G.; Loew, A.; Hangemann, S.; Defourny, P.; Brockmann, C.; Bontemps, S.

    2013-12-01

    Addressing the issues of climate change, the European Space Agency has recently initiated the Global Monitoring of an Essential Climate Variables program (ESA Climate Change Initiative). The main objective is to realize the full potential of the long-term global Earth Observation archives that ESA has established over the last thirty years. Due to well organized data access and transparency for the data quality, as well as long-term scientific and technical support, the provided datasets have become very attractive for the use in Earth System Modeling. The Max Plank Institute for Meteorology is contributing to the ESA CCI via the Climate Modeler User Group (CMUG) activities and is responsible for providing a modeler perspective on the Land Cover and Fire Essential Climate Variables. The new ESA land cover ECV has recently released a new global 300-m land cover dataset. This dataset is supported by an interactive tool which allows flexible horizontal re-scaling and conversion from currently accepted satellite specific land classes to the model- specific Plant Functional Types (PFT) categorization. Such a dataset is an ideal starting point for the generation of the land cover information for the initialization of model cover fractions. In this presentation, we show how the usage of this new dataset affects the model performance, comparing it to the standard model set-up, in terms of energy and water fluxes. To do so, we performed a number of offline land-system simulations with original standard JSBACH land cover information and with the new ESA CCI land cover product. We have analyzed the impact of land cover on a simulated surface albedo, temperature and energy fluxes as well as on the biomass load and fire carbon emissions.

  20. Improving climate model simulation of tropical Atlantic sea surface temperature: The importance of enhanced vertical atmosphere model resolution

    Science.gov (United States)

    Harlaß, Jan; Latif, Mojib; Park, Wonsun

    2015-04-01

    A long-standing problem in climate modeling is the inaccurate simulation of tropical Atlantic (TA) sea surface temperature (SST), known as the TA SST bias. It has far-reaching consequences for climate prediction in that area as it goes along, among others, with erroneous precipitation patterns. We show that the TA SST bias can be largely reduced by increasing both the atmospheric horizontal and vertical resolutions in a climate model. At high horizontal resolution, enhanced vertical resolution is indispensable to substantially improve the simulation of TA SST by enhancing surface wind stress. This also reduces biases in the upper ocean thermal structure and precipitation patterns. Although, enhanced horizontal resolution alone leads to some improvement in the mean climate, typical bias patterns characterized by a reversed zonal SST gradient at the equator and too warm SST in the Benguela upwelling region are mostly unchanged at a coarser vertical resolution.

  1. Multi-model ensemble analysis of Pacific and Atlantic SST variability in unperturbed climate simulations

    Science.gov (United States)

    Zanchettin, D.; Bothe, O.; Rubino, A.; Jungclaus, J. H.

    2016-08-01

    We assess internally-generated climate variability expressed by a multi-model ensemble of unperturbed climate simulations. We focus on basin-scale annual-average sea surface temperatures (SSTs) from twenty multicentennial pre-industrial control simulations contributing to the fifth phase of the Coupled Model Intercomparison Project. Ensemble spatial patterns of regional modes of variability and ensemble (cross-)wavelet-based phase-frequency diagrams of corresponding paired indices summarize the ensemble characteristics of inter-basin and regional-to-global SST interactions on a broad range of timescales. Results reveal that tropical and North Pacific SSTs are a source of simulated interannual global SST variability. The North Atlantic-average SST fluctuates in rough co-phase with the global-average SST on multidecadal timescales, which makes it difficult to discern the Atlantic Multidecadal Variability (AMV) signal from the global signal. The two leading modes of tropical and North Pacific SST variability converge towards co-phase in the multi-model ensemble, indicating that the Pacific Decadal Oscillation (PDO) results from a combination of tropical and extra-tropical processes. No robust inter- or multi-decadal inter-basin SST interaction arises from our ensemble analysis between the Pacific and Atlantic oceans, though specific phase-locked fluctuations occur between Pacific and Atlantic modes of SST variability in individual simulations and/or periods within individual simulations. The multidecadal modulation of PDO by the AMV identified in observations appears to be a recurrent but not typical feature of ensemble-simulated internal variability. Understanding the mechanism(s) and circumstances favoring such inter-basin SST phasing and related uncertainties in their simulated representation could help constraining uncertainty in decadal climate predictions.

  2. National level water quality simulation and climate change scenarios in Finland with WSFS-Vemala model

    Science.gov (United States)

    Huttunen, M.; Huttunen, I.; Seppänen, V.; Vehviläinen, B.

    2012-04-01

    included in the model. For natural background leaching and loading from forestry are used estimated values, process based description is under development. Sedimentation, erosion and denitrification are modelled for rivers. In lakes sedimentation, resuspension, release from sediments and denitrification are modelled. The WSFS-Vemala model is applied for load reduction and country wide climate change scenarios. In load reduction scenarios farming practices and fertilization of each field can be adjusted separately by the characteristics of the field. In climate change scenarios water quality until year 2060 is simulated. For the effects of climate change on agriculture we are using DREMFIA sector model scenarios from MTT Agrifood Research Finland. DREMFIA model gives scenarios as hectars of different crops, fertilization levels and number of cattle in four regions in Finland. Scenarios for point loading, scattered settlements, forestry and background leaching are based on expert estimates. WSFS-Vemala model is then simulated with modified weather, loading and farming input and results include concentrations in rivers and lakes and finally loading into the Baltic Sea. Preliminary scenario results show a slight increase in annual loading and remarkable shift in seasonal loading, with increased loading in winter. WSFS-Vemala model is also applied for real time simulation and forecasting of water quality, including forecasts for chlorophyll-a concentration. Forecasts are provided for the public by www pages at www.environment.fi/waterforecast.

  3. Performance Metrics for Climate Model Evaluation: Application to CMIP5 Precipitation Simulations

    Science.gov (United States)

    Mehran, A.; AghaKouchak, A.; Phillips, T. J.

    2013-12-01

    Validation of gridded climate model simulations is fundamental to future improvements in model developments. Among the metrics, the contingency table, which includes a number of categorical indices, is extensively used in evaluation studies. While the categorical indices offer invaluable information, they do not provide any insight into the volume of the variable detected correctly/incorrectly. In this study, the contingency table categorical metrics are extended to volumetric indices for evaluation of gridded data. The suggested indices include (a) Volumetric Hit Index (VHI): volume of correctly detected simulations relative to the volume of the correctly detected simulations and missed observations; (b) Volumetric False Alarm Ratio (VFAR): volume of false simulations relative to the sum of simulations; (c) Volumetric Miss Index (VMI): volume of missed observations relative to the sum of missed observations and correctly detected simulations; and (d) the Volumetric Critical Success Index (VCSI). The latter provides an overall measure of volumetric performance including volumetric hits, false alarms and misses. Numerous studies have emphasized that climate simulations are subject to various biases and uncertainties. The objective of this study is to cross-validate 34 Coupled Model Inter-comparison Project Phase 5 (CMIP5) historical simulations of precipitation against the Global Precipitation Climatology Project (GPCP) data using the proposed performance metrics, quantifying model pattern discrepancies and biases for both entire data distributions and their upper tails. The results of the Volumetric Hit Index (VHI) analysis of the total monthly precipitation amounts show that most CMIP5 simulations are in good agreement with GPCP patterns in many areas, but their replication of observed precipitation over arid regions and certain sub-continental regions (e.g., northern Eurasia, eastern Russia, central Australia) is problematical. Overall, the VHI of the multi-model

  4. Downscaling a Global Climate Model to Simulate Climate Change Impacts on U.S. Regional and Urban Air Quality

    Science.gov (United States)

    Trail, M.; Tsimpidi, A. P.; Liu, P.; Tsigaridis, K.; Hu, Y.; Nenes, A.; Russell, A. G.

    2013-01-01

    Climate change can exacerbate future regional air pollution events by making conditions more favorable to form high levels of ozone. In this study, we use spectral nudging with WRF to downscale NASA earth system GISS modelE2 results during the years 2006 to 2010 and 2048 to 2052 over the continental United States in order to compare the resulting meteorological fields from the air quality perspective during the four seasons of five-year historic and future climatological periods. GISS results are used as initial and boundary conditions by the WRF RCM to produce hourly meteorological fields. The downscaling technique and choice of physics parameterizations used are evaluated by comparing them with in situ observations. This study investigates changes of similar regional climate conditions down to a 12km by 12km resolution, as well as the effect of evolving climate conditions on the air quality at major U.S. cities. The high resolution simulations produce somewhat different results than the coarse resolution simulations in some regions. Also, through the analysis of the meteorological variables that most strongly influence air quality, we find consistent changes in regional climate that would enhance ozone levels in four regions of the U.S. during fall (Western U.S., Texas, Northeastern, and Southeastern U.S), one region during summer (Texas), and one region where changes potentially would lead to better air quality during spring (Northeast). We also find that daily peak temperatures tend to increase in most major cities in the U.S. which would increase the risk of health problems associated with heat stress. Future work will address a more comprehensive assessment of emissions and chemistry involved in the formation and removal of air pollutants.

  5. Intercomparison of Precipitation Simulated by Regional Climate Models over East Asia in 1997 and 1998

    Institute of Scientific and Technical Information of China (English)

    Dong-Kyou LEE; William J. GUTOWSKI, Jr.; Hyun-Suk KANG; Chun-Ji KIM

    2007-01-01

    Regional climate simulations in Asia from May 1997 to August 1998 were performed using the Seoul National University regional climate model (SNURCM) and Iowa State University regional climate model (ALT.MM5/LSM), which were developed by coupling the NCAR/Land Surface Model (LSM) and the Mesoscale Model (MM5). However, for physical processes of precipitation, the SNURCM used the Grell scheme for the convective parameterization scheme (CPS) and the simple ice scheme for the explicit moisture scheme (EMS), while the ALT.MM5/LSM used the Betts-Miller scheme for CPS and the mixed phase scheme for EMS.The simulated precipitation patterns and amounts over East Asia for the extreme climatic summer in 1997 (relative drought conditions) and 1998 (relative flood conditions) were especially focused upon. The ALT.MM5/LSM simulated more precipitation than was observed in 1997 due to more moisture and cloud water in the lower levels, despite weak upward motion. In the SNURCM, strong upward motion resulted in more precipitation than that was observed in 1998, with more moisture and cloud water in the middle levels. In the ALT.MM5/LSM, weak upward motion, unchanged moisture in the lower troposphere, and the decrease in latent heat flux at the surface increased convective precipitation only by 3% for the 1998 summer event. In the SNURCM, strong upward motion, the increase in moisture in the lower troposphere, and the increase in latent heat flux at the surface increased convective precipitation by 48% for the summer of 1998. The main differences between both simulations were moisture availability and horizontal momentum transport in the lower troposphere, which were also strongly influenced by large-scale forcing.

  6. Coupled Chemistry Climate Model Simulations of Stratospheric Temperature for the Recent Past

    Science.gov (United States)

    Austin, J.

    2007-12-01

    Temperature results for the recent past from multi-decadal simulations of eleven coupled chemistry climate models are analysed using multi-linear regression including a trend, solar cycle and volcanic aerosol terms. The climatology of the models since 1980 is in good agreement with observations for the troposphere but diverge from each other and from observations in the stratosphere. Overall, the models agree better with observations than previous assessments. As a function of latitude and pressure, the simulated trends vary substantially from model to model, although all models show several consistent features. These include statistically significant cooling trends from about the lower stratosphere upwards in the low and middle latitudes. Several models have statistically significant cooling in the lower stratosphere over the polar region. The temporal variation in the global average temperature in the lower stratosphere indicates a clear increase during volcanic eruptions, superimposed on an overall cooling. The model responses to the volcanic aerosol varies by about a factor of two with several models substantially overpredicting the observed response during the 1980s and 1990s. The globally averaged temperature simulated by the models is generally in agreement with corrected satellite observations over much of their range. Model trend comparisons are also shown for the polar spring and illlustrate even larger inter-model differences. These differences are caused by different simulations of trends in planetary waves and ozone amounts, and illustrate the challenge of predicting ozone recovery in polar regions.

  7. Assessment of precipitation and temperature data from CMIP3 global climate models for hydrologic simulation

    Science.gov (United States)

    McMahon, T. A.; Peel, M. C.; Karoly, D. J.

    2015-01-01

    The objective of this paper is to identify better performing Coupled Model Intercomparison Project phase 3 (CMIP3) global climate models (GCMs) that reproduce grid-scale climatological statistics of observed precipitation and temperature for input to hydrologic simulation over global land regions. Current assessments are aimed mainly at examining the performance of GCMs from a climatology perspective and not from a hydrology standpoint. The performance of each GCM in reproducing the precipitation and temperature statistics was ranked and better performing GCMs identified for later analyses. Observed global land surface precipitation and temperature data were drawn from the Climatic Research Unit (CRU) 3.10 gridded data set and re-sampled to the resolution of each GCM for comparison. Observed and GCM-based estimates of mean and standard deviation of annual precipitation, mean annual temperature, mean monthly precipitation and temperature and Köppen-Geiger climate type were compared. The main metrics for assessing GCM performance were the Nash-Sutcliffe efficiency (NSE) index and root mean square error (RMSE) between modelled and observed long-term statistics. This information combined with a literature review of the performance of the CMIP3 models identified the following better performing GCMs from a hydrologic perspective: HadCM3 (Hadley Centre for Climate Prediction and Research), MIROCm (Model for Interdisciplinary Research on Climate) (Center for Climate System Research (The University of Tokyo), National Institute for Environmental Studies, and Frontier Research Center for Global Change), MIUB (Meteorological Institute of the University of Bonn, Meteorological Research Institute of KMA, and Model and Data group), MPI (Max Planck Institute for Meteorology) and MRI (Japan Meteorological Research Institute). The future response of these GCMs was found to be representative of the 44 GCM ensemble members which confirms that the selected GCMs are reasonably

  8. Streamflow in the upper Mississippi river basin as simulated by SWAT driven by 20{sup th} century contemporary results of global climate models and NARCCAP regional climate models

    Energy Technology Data Exchange (ETDEWEB)

    Takle, Eugene S.; Jha, Manoj; Lu, Er; Arritt, Raymond W.; Gutowski, William J. [Iowa State Univ. Ames, IA (United States)

    2010-06-15

    We use Soil and Water Assessment Tool (SWAT) when driven by observations and results of climate models to evaluate hydrological quantities, including streamflow, in the Upper Mississippi River Basin (UMRB) for 1981-2003 in comparison to observed streamflow. Daily meteorological conditions used as input to SWAT are taken from (1) observations at weather stations in the basin, (2) daily meteorological conditions simulated by a collection of regional climate models (RCMs) driven by reanalysis boundary conditions, and (3) daily meteorological conditions simulated by a collection of global climate models (GCMs). Regional models used are those whose data are archived by the North American Regional Climate Change Assessment Program (NARCCAP). Results show that regional models correctly simulate the seasonal cycle of precipitation, temperature, and streamflow within the basin. Regional models also capture interannual extremes represented by the flood of 1993 and the dry conditions of 2000. The ensemble means of both the GCM-driven and RCM-driven simulations by SWAT capture both the timing and amplitude of the seasonal cycle of streamflow with neither demonstrating significant superiority at the basin level. (orig.)

  9. Modeled response of the West Nile virus vector Culex quinquefasciatus to changing climate using the dynamic mosquito simulation model

    Science.gov (United States)

    Morin, Cory W.; Comrie, Andrew C.

    2010-09-01

    Climate can strongly influence the population dynamics of disease vectors and is consequently a key component of disease ecology. Future climate change and variability may alter the location and seasonality of many disease vectors, possibly increasing the risk of disease transmission to humans. The mosquito species Culex quinquefasciatus is a concern across the southern United States because of its role as a West Nile virus vector and its affinity for urban environments. Using established relationships between atmospheric variables (temperature and precipitation) and mosquito development, we have created the Dynamic Mosquito Simulation Model (DyMSiM) to simulate Cx. quinquefasciatus population dynamics. The model is driven with climate data and validated against mosquito count data from Pasco County, Florida and Coachella Valley, California. Using 1-week and 2-week filters, mosquito trap data are reproduced well by the model ( P climate projection data generated by the National Center for Atmospheric Research CCSM3 general circulation model, we applied temperature and precipitation offsets to the climate data at each location to evaluate mosquito population sensitivity to possible future climate conditions. We found that temperature and precipitation shifts act interdependently to cause remarkable changes in modeled mosquito population dynamics. Impacts include a summer population decline from drying in California due to loss of immature mosquito habitats, and in Florida a decrease in late-season mosquito populations due to drier late summer conditions.

  10. The West African Monsoon simulated by global and regional climate models

    Science.gov (United States)

    Nikulin, Grigory; Jones, Colin; Kjellström, Erik; Gbobaniyi, Emiola

    2013-04-01

    We present results from two ensembles of global and regional climate simulations with a focus on the West African Monsoon (WAM). The first ensemble includes eight coupled atmosphere ocean general circulation models (AOGCMs) from the CMIP5 project, namely: CanESM2, CNRM-CM5, HadGEM2-ES, NorESM1-M, EC-EARTH, MIROC5, GFDL-ESM2M and MPI-ESM-LR. The second ensemble consists of corresponding downscaling of all 8 AOGCMs by a regional climate model - RCA4 produced at the Rossby Centre (SMHI) in the Africa-CORDEX activities. Spatial resolution varies from about 1° to 3° in the AOGCM ensemble while all regional simulations are at the same 0.44° resolution. To see what added value higher resolution can provide ability of the eight AOGCMs and the downscaled RCA4(AOGCMs) to simulate the key characteristics of the WAM rainy season are evaluated and then inter-compared between the global and regional ensembles. The main focus in our analysis is on the WAM rainy season onset, cessation, length, total precipitation, its mean intensity and intraseasonal variability. Future climate projections under the RCP45 and RCP85 scenarios are analyzed and again inter-compared for both ensembles in order to assess uncertainties in the future projections of the WAM rainy season from the global and regional ensembles.

  11. Simulation of land surface temperatures: comparison of two climate models and satellite retrievals

    Directory of Open Access Journals (Sweden)

    J. M. Edwards

    2009-03-01

    Full Text Available Recently there has been significant progress in the retrieval of land surface temperature from satellite observations. Satellite retrievals of surface temperature offer several advantages, including broad spatial coverage, and such data are potentially of great value in assessing general circulation models of the atmosphere. Here, retrievals of the land surface temperature over the contiguous United States are compared with simulations from two climate models. The models generally simulate the diurnal range realistically, but show significant warm biases during the summer. The models' diurnal cycle of surface temperature is related to their surface flux budgets. Differences in the diurnal cycle of the surface flux budget between the models are found to be more pronounced than those in the diurnal cycle of surface temperature.

  12. A numerical model to simulate physical states of snowpack for climate studies

    Science.gov (United States)

    Niwano, M.; Aoki, T.; Kuchiki, K.; Hosaka, M.; Kodama, Y.

    2011-12-01

    In recent years, several physically based snow albedo models for general circulation models (GCMs) have been developed to improve the accuracy of climate simulations. Since these snow albedo models generally require snow grain size or specific surface area of snow as an input parameter, internal physical states of snowpack should also be calculated accurately in GCMs. For this reason, we developed a multilayered physical snowpack model named Snow Metamorphism and Albedo Process (SMAP) model. SMAP model takes energy balance, mass balance, snow settlement, phase changes, water percolation, and snow metamorphism into account. We validated SMAP model using meteorological and snow impurities (black carbon and dust) data measured during 2007-2009 winters (November to April) at Sapporo, Japan. The root mean square error (RMSE) values of snow depth were 0.064 m for 2007-2008 winter and 0.075 m for 2008-2009 winter. The RMSE values of shortwave albedo were 0.051 for 2007-2008 winter and 0.084 for 2008-2009. Although the RMSE value of shortwave albedo during 2008-2009 winter was somewhat large, it was attributed to an error that SMAP model could not simulate rapid complete melting. In fact, we obtained the RMSE value of 0.048 from 1 January to 15 March, 2009 when simulated snowpack continuously survived whole time. These results confirm that SMAP model can be used for climate simulations as well as studies on snow physical processes. Using SMAP model, we investigated the effects of snow impurities on snowmelt at Sapporo by means of "pure snow experiment". We found that snowpack durations at Sapporo were shortened by 19 days during 2007-2008 winter and 16 days during 2008-2009 winter by the forcing of snow impurities.

  13. Albedo and heat transport in 3-D model simulations of the early Archean climate

    Directory of Open Access Journals (Sweden)

    H. Kienert

    2013-08-01

    Full Text Available At the beginning of the Archean eon (ca. 3.8 billion years ago, the Earth's climate state was significantly different from today due to the lower solar luminosity, smaller continental fraction, higher rotation rate and, presumably, significantly larger greenhouse gas concentrations. All these aspects play a role in solutions to the "faint young Sun paradox" which must explain why the ocean surface was not fully frozen at that time. Here, we present 3-D model simulations of climate states that are consistent with early Archean boundary conditions and have different CO2 concentrations, aiming at an understanding of the fundamental characteristics of the early Archean climate system. In order to do so, we have appropriately modified an intermediate complexity climate model that couples a statistical-dynamical atmosphere model (involving parameterizations of the dynamics to an ocean general circulation model and a thermodynamic-dynamic sea-ice model. We focus on three states: one of them is ice-free, one has the same mean surface air temperature of 288 K as today's Earth and the third one is the coldest stable state in which there is still an area with liquid surface water (i.e. the critical state at the transition to a "snowball Earth". We find a reduction in meridional heat transport compared to today, which leads to a steeper latitudinal temperature profile and has atmospheric as well as oceanic contributions. Ocean surface velocities are largely zonal, and the strength of the atmospheric meridional circulation is significantly reduced in all three states. These aspects contribute to the observed relation between global mean temperature and albedo, which we suggest as a parameterization of the ice-albedo feedback for 1-D model simulations of the early Archean and thus the faint young Sun problem.

  14. A simple regional coupled model experiment for summer-time climate simulation over southern Africa

    Energy Technology Data Exchange (ETDEWEB)

    Ratnam, J.V.; Behera, S.K. [Research Institute for Global Change, Yokohama, Kanagawa (Japan); Application Laboratory, Yokohama (Japan); Masumoto, Y. [Research Institute for Global Change, Yokohama, Kanagawa (Japan); Takahashi, K. [Application Laboratory, Yokohama (Japan); Earth Simulator Center, Yokohama (Japan); Yamagata, T. [Application Laboratory, Yokohama (Japan); The University of Tokyo, School of Science, Tokyo (Japan)

    2012-11-15

    The main aim of this paper is to evaluate the Advanced Research Weather Research and Forecasting (WRF) regional model in simulating the precipitation over southern Africa during austral summer. The model's ability to reproduce the southern African mean climate and its variability around this mean state was evaluated by using the two-tier approach of specifying sea surface temperature (SST) to WRF and by using the one-tier approach of coupling the WRF with a simple mixed-layer ocean model. The boundary conditions provided by the reanalysis-II data were used for the simulations. Model experiments were conducted for twelve austral summers from DJF1998-99 to DJF2009-10. The experiments using both the two-tier and one-tier approaches simulated the spatial and temporal distributions of the precipitation realistically. However, both experiments simulated negative biases over Mozambique. Furthermore, analysis of the wet and dry spells revealed that the one-tier approach is superior to the two-tier approach. Based on the analysis of the surface temperature and the zonal wind shear it is noted that the simple mixed-layer ocean model coupled to WRF can be effectively used in place of two-tier WRF to simulate the climate of southern Africa. This is an important result because specification of SST at higher temporal resolutions in the subtropics is the most difficult task in the two-tier approach for most regional prediction models. The one-tier approach with the simple mixed-layer model can effectively reduce the complicacy of finding good SST predictions. (orig.)

  15. Comparison of Explicitly Simulated and Downscaled Tropical Cyclone Activity in a High-Resolution Global Climate Model

    Directory of Open Access Journals (Sweden)

    Hirofumi Tomita

    2010-01-01

    Full Text Available The response of tropical cyclone activity to climate change is a matter of great inherent interest and practical importance. Most current global climate models are not, however, capable of adequately resolving tropical cyclones; this has led to the development of downscaling techniques designed to infer tropical cyclone activity from the large-scale fields produced by climate models. Here we compare the statistics of tropical cyclones simulated explicitly in a very high resolution (~14 km grid mesh global climate model to the results of one such downscaling technique driven by the same global model. This is done for a simulation of the current climate and also for a simulation of a climate warmed by the addition of carbon dioxide. The explicitly simulated and downscaled storms are similarly distributed in space, but the intensity distribution of the downscaled events has a somewhat longer high-intensity tail, owing to the higher resolution of the downscaling model. Both explicitly simulated and downscaled events show large increases in the frequency of events at the high-intensity ends of their respective intensity distributions, but the downscaled storms also show increases in low-intensity events, whereas the explicitly simulated weaker events decline in number. On the regional scale, there are large differences in the responses of the explicitly simulated and downscaled events to global warming. In particular, the power dissipation of downscaled events shows a 175% increase in the Atlantic, while the power dissipation of explicitly simulated events declines there.

  16. Cloud cover diurnal cycles in satellite data and regional climate model simulations

    Energy Technology Data Exchange (ETDEWEB)

    Pfeifroth, Uwe; Ahrens, Bodo [Frankfurt Univ., Frankfurt am Main (Germany). Inst. for Atmospheric and Environmental Sciences; Hollmann, Rainer [Deutscher Wetterdienst, Offenbach (Germany)

    2012-12-15

    The amount and diurnal cycle of cloud cover play an important role in the energy and water cycle of the earth-atmosphere system and influence the radiation budget of the earth. Due to its importance and the challenging nature of its quantification, cloud cover is considered the biggest uncertainty factor in climate modeling. There is a clear need for reliable cloud datasets suitable for climate model evaluation studies. This study analyzes two datasets of cloud cover and its diurnal cycle derived from satellite observations by the International Satellite Cloud Climatology Project (ISCCP) and by EUMETSAT's Satellite Application Facility on Climate Monitoring (CM SAF) in Africa and Europe. Two regions, Europe and the subtropical southern Atlantic Ocean, were identified as offering distinct cloud cover diurnal cycles reasonably observed by both satellite datasets. In these regions, simulations by the regional climate model COSMO-CLM (CCLM) were evaluated in terms of cloud cover and its diurnal cycle during the time period of 1990 to 2007. Results show that the satellite derived cloud diurnal cycles largely agree, while discrepancies occur under extreme conditions like in the Sahara region. The CCLM is able to simulate the diurnal cycle observed consistently in the two satellite datasets in the South-Atlantic ocean, but not in Europe. CCLM misses the afternoon maximum cloud cover in Summer in Europe, which implies deficiencies in the parameterization of convection and in the treatment of surface-atmosphere interactions. The simulation of the diurnal cycle of the more stratiform cloud cover over the subtropical Atlantic was satisfactory in CCLM. (orig.)

  17. Spatial analysis of future East Asian seasonal temperature using two regional climate model simulations

    Science.gov (United States)

    Kim, Yura; Jun, Mikyoung; Min, Seung-Ki; Suh, Myoung-Seok; Kang, Hyun-Suk

    2016-05-01

    CORDEX-East Asia, a branch of the coordinated regional climate downscaling experiment (CORDEX) initiative, provides high-resolution climate simulations for the domain covering East Asia. This study analyzes temperature data from regional climate models (RCMs) participating in the CORDEX - East Asia region, accounting for the spatial dependence structure of the data. In particular, we assess similarities and dissimilarities of the outputs from two RCMs, HadGEM3-RA and RegCM4, over the region and over time. A Bayesian functional analysis of variance (ANOVA) approach is used to simultaneously model the temperature patterns from the two RCMs for the current and future climate. We exploit nonstationary spatial models to handle the spatial dependence structure of the temperature variable, which depends heavily on latitude and altitude. For a seasonal comparison, we examine changes in the winter temperature in addition to the summer temperature data. We find that the temperature increase projected by RegCM4 tends to be smaller than the projection of HadGEM3-RA for summers, and that the future warming projected by HadGEM3-RA tends to be weaker for winters. Also, the results show that there will be a warming of 1-3°C over the region in 45 years. More specifically, the warming pattern clearly depends on the latitude, with greater temperature increases in higher latitude areas, which implies that warming may be more severe in the northern part of the domain.

  18. Significant Features Found in Simulated Tropical Climates Using a Cloud Resolving Model

    Science.gov (United States)

    Shie, C.-L.; Tao, W.-K.; Simpson, J.; Sui, C.-H.

    2000-01-01

    Cloud resolving model (CRM) has widely been used in recent years for simulations involving studies of radiative-convective systems and their role in determining the tropical regional climate. The growing popularity of CRMs usage can be credited for their inclusion of crucial and realistic features such like explicit cloud-scale dynamics, sophisticated microphysical processes, and explicit radiative-convective interaction. For example, by using a two-dimensional cloud model with radiative-convective interaction process, found a QBO-like (quasibiennial oscillation) oscillation of mean zonal wind that affected the convective system. Accordingly, the model-generated rain band corresponding to convective activity propagated in the direction of the low-level zonal mean winds; however, the precipitation became "localized" (limited within a small portion of the domain) as zonal mean winds were removed. Two other CRM simulations by S94 and Grabowski et al. (1996, hereafter G96), respectively that produced distinctive quasi-equilibrium ("climate") states on both tropical water and energy, i.e., a cold/dry state in S94 and a warm/wet state in G96, have later been investigated by T99. They found that the pattern of the imposed large-scale horizontal wind and the magnitude of the imposed surface fluxes were the two crucial mechanisms in determining the tropical climate states. The warm/wet climate was found associated with prescribed strong surface winds, or with maintained strong vertical wind shears that well-organized convective systems prevailed. On the other hand, the cold/dry climate was produced due to imposed weak surface winds and weak wind shears throughout a vertically mixing process by convection. In this study, considered as a sequel of T99, the model simulations to be presented are generally similar to those of T99 (where a detailed model setup can be found), except for a more detailed discussion along with few more simulated experiments. There are twelve major

  19. The Effects of Model Resolution on the Simulation of Regional Climate Extreme Events

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The fifth-generation Pennsylvania State University/NCAR Mesoscale Model Version 3 (MM5V3) was used to simulate extreme heavy rainfall events over the Yangtze River Basin in June 1999. The effects of model's horizontal and vertical resolution on the extreme climate events were investigated in detail. In principle, the model was able to characterize the spatial distribution of monthly heavy precipitation. The results indicated that the increase in horizontal resolution could reduce the bias of the modeled heavy rain and reasonably simulate the change of daily precipitation during the study period. A finer vertical resolution led to obviously improve rainfall simulations with smaller biases, and hence, better resolve heavy rainfall events. The increase in both horizontal and vertical resolution could produce better predictions of heavy rainfall events. Not only the rainfall simulation altered in the cases of different horizontal and vertical grid spacing, but also other meteorological fields demonstrated diverse variations in terms of resolution change in the model. An evident improvement in the simulated sea level pressure resulted from the increase of horizontal resolution, but the simulation was insensitive to vertical grid spacing. The increase in vertical resolution could enhance the simulation of surface temperature as well as atmospheric circulation at low levels, while the simulation of circulation at middle and upper levels were found to be much less dependent on changing resolution. In addition, cumulus parameterization schemes showed high sensitivity to horizontal resolution. Different convective schemes exhibited large discrepancies in rainfall simulations with regards to changing resolution. The percentage of convective precipitation in the Grell scheme increased with increasing horizontal resolution. In contrast, the Kain-Fritsch scheme caused a reduced ratio of convective precipitation to total rainfall accumulations corresponding to increasing

  20. Simulated discharge trends indicate robustness of hydrological models in a changing climate

    Science.gov (United States)

    Addor, Nans; Nikolova, Silviya; Seibert, Jan

    2016-04-01

    Assessing the robustness of hydrological models under contrasted climatic conditions should be part any hydrological model evaluation. Robust models are particularly important for climate impact studies, as models performing well under current conditions are not necessarily capable of correctly simulating hydrological perturbations caused by climate change. A pressing issue is the usually assumed stationarity of parameter values over time. Modeling experiments using conceptual hydrological models revealed that assuming transposability of parameters values in changing climatic conditions can lead to significant biases in discharge simulations. This raises the question whether parameter values should to be modified over time to reflect changes in hydrological processes induced by climate change. Such a question denotes a focus on the contribution of internal processes (i.e., catchment processes) to discharge generation. Here we adopt a different perspective and explore the contribution of external forcing (i.e., changes in precipitation and temperature) to changes in discharge. We argue that in a robust hydrological model, discharge variability should be induced by changes in the boundary conditions, and not by changes in parameter values. In this study, we explore how well the conceptual hydrological model HBV captures transient changes in hydrological signatures over the period 1970-2009. Our analysis focuses on research catchments in Switzerland undisturbed by human activities. The precipitation and temperature forcing are extracted from recently released 2km gridded data sets. We use a genetic algorithm to calibrate HBV for the whole 40-year period and for the eight successive 5-year periods to assess eventual trends in parameter values. Model calibration is run multiple times to account for parameter uncertainty. We find that in alpine catchments showing a significant increase of winter discharge, this trend can be captured reasonably well with constant

  1. Simulation of recent and future climates using CNRM and IPSL models; Simulation du climat recent et futur par les modeles du CNRM et de l'IPSL

    Energy Technology Data Exchange (ETDEWEB)

    Dufresne, J.L.; Bony, S.; Fairhead, L.; Grandpeix, J.Y.; Hourdin, F.; Idelkadi, A.; Musat, I. [Universite Pierre et Marie Curie, Lab. de Meteorologie Dynamique (LMD-IPSL), CNRS, 75 - Paris (France); Salas y Melia, D.; Tyteca, S.; Chauvin, F.; Deque, M.; Douville, H.; Gueremy, J.F.; Marquet, P.; Planton, S.; Royer, J.F.; Voldoire, A. [Meteo France Centre National de Recherches Meteorologiques, 31 - Toulouse (France); Denvil, S.; Cadule, P.; Foujols, M.A. [Universite Pierre et Marie Curie, Institut Pierre-Simon Laplace, CNRS, 75 - Paris (France); Arzel, O.; Fichefet, T. [Universite Catholique de Louvain (UCL), Louvain-la-Neuve (Belgium). Inst. d' Astronomie et de Geophysique G. Lemaitre; Braconnot, P.; Brockmann, P.; Caubel, A.; Friedlingstein, P.; Marti, O.; Swingedouw, D. [Laboratoire des Sciences du Climat et de l' Environnement, Domaine du CNRS, 91 - Gif Sur Yvette (France); Krinner, G. [Universite Joseph-Fourier, Grenoble I, Lab. de Glaciologie et Geophysique de l' Environnement (LGGE), CNRS, 38 - Saint Martin d' Heres (France); Levy, C.; Madec, G. [Universite Pierre et Marie Curie, Lab. d' Oceanographie et Climat (Locean-IPLS), CNRS, 75 - Paris (France)

    2006-11-15

    In support of the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) that should appear in early 2007, modelling groups world-wide have performed a huge coordinated exercise of climate change runs for the 20. and 21. centuries. In this paper we present the results of the two French climate models, CNRM and IPSL. In particular we emphasize the progress made since the previous IPCC report and we identify which results are comparable among models and which strongly differ. (authors)

  2. Coupled Model Simulations of Climate Changes in the 20th Century and Beyond

    Institute of Scientific and Technical Information of China (English)

    YU Jiaqiang; ZHI Hai; WANG Bin; WAN Hui; LI Chai; LIU Hailong; LI Wei; ZHENG Weipeng; ZHOU Tianjun

    2008-01-01

    Several scenario experiments of the IPCC 4th Assessment Report (AR4) are performed by version g1.0 of a Flexible coupled Ocean-Atmosphere-Land System Model (FGOALS) developed at the Institute of At- mospheric Physics, Chinese Academy of Sciences (IAP/CAS), including the "Climate of the 20th century experiment", "CO2 1% increase per year to doubling experiment" and two separate IPCC greenhouse gases emission scenarios AIB and B1 experiments. To distinguish between the different impacts of natural vari- ations and human activities on the climate change, three-member ensemble runs are performed for each scenario experiment. The coupled model simulations show: (1) from 1900 to 2000, the global mean temper- ature increases about 0.5℃ and the major increase occurs during the later half of the 20th century, which is in consistent with the observations that highlights the coupled model's ability to reproduce the climate changes since the industrial revolution; (2) the global mean surface air temperature increases about 1.6℃ in the CO2 doubling experiment and 1.5℃ and 2.4℃ in the AlB and Bl scenarios, respectively. The global warming is indicated by not only the changes of the surface temperature and precipitation but also the temperature increase in the deep ocean. The thermal expansion of the sea water would induce the rise of the global mean sea level. Both the control run and the 20th century climate change run are carried out again with version g1.1 of FGOALS, in which the cold biases in the high latitudes were removed. They are then compared with those from version g1.0 of FGOALS in order to distinguish the effect of the model biases on the simulation of global warming.

  3. Projected changes in atmospheric river events in Arizona as simulated by global and regional climate models

    Science.gov (United States)

    Rivera, Erick R.; Dominguez, Francina

    2016-09-01

    Inland-penetrating atmospheric rivers (ARs) affect the United States Southwest and significantly contribute to cool season precipitation. In this study, we examine the results from an ensemble of dynamically downscaled simulations from the North American Regional Climate Change Assessment Program (NARCCAP) and their driving general circulation models (GCMs) in order to determine statistically significant changes in the intensity of the cool season ARs impacting Arizona and the associated precipitation. Future greenhouse gas emissions follow the A2 emission scenario from the Intergovernmental Panel on Climate Change Fourth Assessment Report simulations. We find that there is a consistent and clear intensification of the AR-related water vapor transport in both the global and regional simulations which reflects the increase in water vapor content due to warmer atmospheric temperatures, according to the Clausius-Clapeyron relationship. However, the response of AR-related precipitation intensity to increased moisture flux and column-integrated water vapor is weak and no significant changes are projected either by the GCMs or the NARCCAP models. This lack of robust precipitation variations can be explained in part by the absence of meaningful changes in both the large-scale water vapor flux convergence and the maximum positive relative vorticity in the GCMs. Additionally, some global models show a robust decrease in relative humidity which may also be responsible for the projected precipitation patterns.

  4. Coupled model simulations of climate changes in the 20th century and beyond

    Science.gov (United States)

    Yu, Yongqiang; Zhi, Hai; Wang, Bin; Wan, Hui; Li, Chao; Liu, Hailong; Li, Wei; Zheng, Weipeng; Zhou, Tianjun

    2008-07-01

    Several scenario experiments of the IPCC 4th Assessment Report (AR4) are performed by version g1.0 of a Flexible coupled Ocean-Atmosphere-Land System Model (FGOALS) developed at the Institute of Atmospheric Physics, Chinese Academy of Sciences (IAP/CAS), including the “Climate of the 20th century experiment”, “CO2 1% increase per year to doubling experiment” and two separate IPCC greenhouse gases emission scenarios A1B and B1 experiments. To distinguish between the different impacts of natural variations and human activities on the climate change, three-member ensemble runs are performed for each scenario experiment. The coupled model simulations show: (1) from 1900 to 2000, the global mean temperature increases about 0.5°C and the major increase occurs during the later half of the 20th century, which is in consistent with the observations that highlights the coupled model’s ability to reproduce the climate changes since the industrial revolution; (2) the global mean surface air temperature increases about 1.6°C in the CO2 doubling experiment and 1.5°C and 2.4°C in the A1B and B1 scenarios, respectively. The global warming is indicated by not only the changes of the surface temperature and precipitation but also the temperature increase in the deep ocean. The thermal expansion of the sea water would induce the rise of the global mean sea level. Both the control run and the 20th century climate change run are carried out again with version g1.1 of FGOALS, in which the cold biases in the high latitudes were removed. They are then compared with those from version g1.0 of FGOALS in order to distinguish the effect of the model biases on the simulation of global warming.

  5. Arctic climate changes in the 21st century: Ensemble model estimates accounting for realism in present-day climate simulation

    Science.gov (United States)

    Eliseev, A. V.; Semenov, V. A.

    2016-11-01

    In the course of forecasting future climate changes in the Arctic Region based on calculations and an ensemble of the state-of-the-art global climate models, the results depend on the method of construction the statistics from the models.

  6. Extended contingency table: Performance metrics for satellite observations and climate model simulations

    Science.gov (United States)

    AghaKouchak, A.; Mehran, A.

    2013-10-01

    Validation of gridded satellite observations and climate model simulations are fundamental to future improvements in retrieval algorithms and model developments. Among the metrics, the contingency table, which includes a number of categorical indices, is extensively used in evaluation studies. While the categorical indices offer invaluable information, they do not provide any insight into the volume of the variable detected correctly/incorrectly. In this study, the contingency table categorical metrics are extended to volumetric indices for evaluation of gridded data. The suggested indices include (a) Volumetric Hit Index (VHI): volume of correctly detected simulations relative to the volume of the correctly detected simulations and missed observations; (b) Volumetric False Alarm Ratio (VFAR): volume of false simulations relative to the sum of simulations; (c) Volumetric Miss Index (VMI): volume of missed observations relative to the sum of missed observations and correctly detected simulations; and (d) the Volumetric Critical Success Index (VCSI). The latter provides an overall measure of volumetric performance including volumetric hits, false alarms, and misses. First, using two synthetic time series, the volumetric indices are evaluated against the contingency table categorical metrics. Then, the volumetric indices are used to evaluate a gridded data set at the continental scale. The results show that the volumetric indices provide additional information beyond the commonly used categorical metrics that can be useful in evaluating gridded data sets.

  7. Reinitialised versus continuous regional climate simulations using ALARO-0 coupled to the land surface model SURFEXv5

    Science.gov (United States)

    Berckmans, Julie; Giot, Olivier; De Troch, Rozemien; Hamdi, Rafiq; Ceulemans, Reinhart; Termonia, Piet

    2017-01-01

    Dynamical downscaling in a continuous approach using initial and boundary conditions from a reanalysis or a global climate model is a common method for simulating the regional climate. The simulation potential can be improved by applying an alternative approach of reinitialising the atmosphere, combined with either a daily reinitialised or a continuous land surface. We evaluated the dependence of the simulation potential on the running mode of the regional climate model ALARO coupled to the land surface model Météo-France SURFace EXternalisée (SURFEX), and driven by the ERA-Interim reanalysis. Three types of downscaling simulations were carried out for a 10-year period from 1991 to 2000, over a western European domain at 20 km horizontal resolution: (1) a continuous simulation of both the atmosphere and the land surface, (2) a simulation with daily reinitialisations for both the atmosphere and the land surface and (3) a simulation with daily reinitialisations of the atmosphere while the land surface is kept continuous. The results showed that the daily reinitialisation of the atmosphere improved the simulation of the 2 m temperature for all seasons. It revealed a neutral impact on the daily precipitation totals during winter, but the results were improved for the summer when the land surface was kept continuous. The behaviour of the three model configurations varied among different climatic regimes. Their seasonal cycle for the 2 m temperature and daily precipitation totals was very similar for a Mediterranean climate, but more variable for temperate and continental climate regimes. Commonly, the summer climate is characterised by strong interactions between the atmosphere and the land surface. The results for summer demonstrated that the use of a daily reinitialised atmosphere improved the representation of the partitioning of the surface energy fluxes. Therefore, we recommend using the alternative approach of the daily reinitialisation of the atmosphere for

  8. Abrupt climate change and high to low latitude teleconnections as simulated in climate models

    DEFF Research Database (Denmark)

    Cvijanovic, Ivana

    of the present day atmospheric mid-latitude energy transport compared to that of the Last Glacial Maximum, suggesting its ability to reorganize more easily and thereby dampen high latitude temperature anomalies that could arise from changes in the oceanic transport. The role of tropical SSTs in the tropical...... precipitation shifts was further re-examined in idealized simulations with the fixed tropical sea surface temperatures, showing that the SST changes are fundamental to the tropical precipitation shifts. Regarding the high latitude energy loss, it was shown that the main energy compensation comes from...... the southern tropics, with the energy gain originating from the cloud radiative feedbacks, temperature and longwave water vapor feedbacks. Extended consideration of the various scenarios that can induce the southward precipitation shifts showed that the Southern Hemisphere warming simulations, in addition...

  9. Demonstration of a geostatistical approach to physically consistent downscaling of climate modeling simulations

    KAUST Repository

    Jha, Sanjeev Kumar

    2013-01-01

    A downscaling approach based on multiple-point geostatistics (MPS) is presented. The key concept underlying MPS is to sample spatial patterns from within training images, which can then be used in characterizing the relationship between different variables across multiple scales. The approach is used here to downscale climate variables including skin surface temperature (TSK), soil moisture (SMOIS), and latent heat flux (LH). The performance of the approach is assessed by applying it to data derived from a regional climate model of the Murray-Darling basin in southeast Australia, using model outputs at two spatial resolutions of 50 and 10 km. The data used in this study cover the period from 1985 to 2006, with 1985 to 2005 used for generating the training images that define the relationships of the variables across the different spatial scales. Subsequently, the spatial distributions for the variables in the year 2006 are determined at 10 km resolution using the 50 km resolution data as input. The MPS geostatistical downscaling approach reproduces the spatial distribution of TSK, SMOIS, and LH at 10 km resolution with the correct spatial patterns over different seasons, while providing uncertainty estimates through the use of multiple realizations. The technique has the potential to not only bridge issues of spatial resolution in regional and global climate model simulations but also in feature sharpening in remote sensing applications through image fusion, filling gaps in spatial data, evaluating downscaled variables with available remote sensing images, and aggregating/disaggregating hydrological and groundwater variables for catchment studies.

  10. Remote sensing of aerosols in the Arctic for an evaluation of global climate model simulations.

    Science.gov (United States)

    Glantz, Paul; Bourassa, Adam; Herber, Andreas; Iversen, Trond; Karlsson, Johannes; Kirkevåg, Alf; Maturilli, Marion; Seland, Øyvind; Stebel, Kerstin; Struthers, Hamish; Tesche, Matthias; Thomason, Larry

    2014-07-16

    In this study Moderate Resolution Imaging Spectroradiometer (MODIS) Aqua retrievals of aerosol optical thickness (AOT) at 555 nm are compared to Sun photometer measurements from Svalbard for a period of 9 years. For the 642 daily coincident measurements that were obtained, MODIS AOT generally varies within the predicted uncertainty of the retrieval over ocean (ΔAOT = ±0.03 ± 0.05 · AOT). The results from the remote sensing have been used to examine the accuracy in estimates of aerosol optical properties in the Arctic, generated by global climate models and from in situ measurements at the Zeppelin station, Svalbard. AOT simulated with the Norwegian Earth System Model/Community Atmosphere Model version 4 Oslo global climate model does not reproduce the observed seasonal variability of the Arctic aerosol. The model overestimates clear-sky AOT by nearly a factor of 2 for the background summer season, while tending to underestimate the values in the spring season. Furthermore, large differences in all-sky AOT of up to 1 order of magnitude are found for the Coupled Model Intercomparison Project phase 5 model ensemble for the spring and summer seasons. Large differences between satellite/ground-based remote sensing of AOT and AOT estimated from dry and humidified scattering coefficients are found for the subarctic marine boundary layer in summer.

  11. Aerosol microphysics simulations of the Mt. Pinatubo eruption with the UKCA composition-climate model

    Directory of Open Access Journals (Sweden)

    S. S. Dhomse

    2014-01-01

    Full Text Available We have enhanced the capability of a microphysical aerosol-chemistry module to simulate the atmospheric aerosol and precursor gases for both tropospheric and stratospheric conditions. Using the Mount Pinatubo eruption (June 1991 as a test case, we evaluate simulated aerosol properties in a composition-climate model against a range of satellite and in-situ observations. Simulations are performed assuming an injection of 20 Tg SO2 at 19–27 km in tropical latitudes, without any radiative feedback from the simulated aerosol. In both quiescent and volcanically perturbed conditions, simulated aerosol properties in the lower stratosphere show reasonable agreement with the observations. The model captures the observed timing of the maximum aerosol optical depth (AOD and its decay timescale in both tropics and Northern Hemisphere (NH mid-latitudes. There is also good qualitative agreement with the observations in terms of spatial and temporal variation of the aerosol effective radius (Reff, which peaks 6–8 months after the eruption. However, the model shows significant biases against some observational data sets. Simulated AOD and Surface Area Density (SAD in the tropics are substantially higher than the gap-filled satellite data products during the first 6 months after the eruption. The model shows consistently weaker enhancement in Reff compared to satellite and in-situ measurements. Simulated aerosol particle size distribution is also compared to NH mid-latitude in-situ balloon sounding measurements of size-resolved number concentrations. Before the eruption, the model captures the observed profiles of lower stratospheric particle number concentrations with radii larger than 5, 150 and 250 nm (N5, N150 and N250 very well. However, in the first 6 months after the eruption, the model shows high bias in N5 concentrations in the lower stratosphere, suggesting too strong nucleation. Following particle growth via condensation and coagulation, this bias

  12. The Impact of Sea Ice Concentration Accuracies on Climate Model Simulations with the GISS GCM

    Science.gov (United States)

    Parkinson, Claire L.; Rind, David; Healy, Richard J.; Martinson, Douglas G.; Zukor, Dorothy J. (Technical Monitor)

    2000-01-01

    The Goddard Institute for Space Studies global climate model (GISS GCM) is used to examine the sensitivity of the simulated climate to sea ice concentration specifications in the type of simulation done in the Atmospheric Modeling Intercomparison Project (AMIP), with specified oceanic boundary conditions. Results show that sea ice concentration uncertainties of +/- 7% can affect simulated regional temperatures by more than 6 C, and biases in sea ice concentrations of +7% and -7% alter simulated annually averaged global surface air temperatures by -0.10 C and +0.17 C, respectively, over those in the control simulation. The resulting 0.27 C difference in simulated annual global surface air temperatures is reduced by a third, to 0.18 C, when considering instead biases of +4% and -4%. More broadly, least-squares fits through the temperature results of 17 simulations with ice concentration input changes ranging from increases of 50% versus the control simulation to decreases of 50% yield a yearly average global impact of 0.0107 C warming for every 1% ice concentration decrease, i.e., 1.07 C warming for the full +50% to -50% range. Regionally and on a monthly average basis, the differences can be far greater, especially in the polar regions, where wintertime contrasts between the +50% and -50% cases can exceed 30 C. However, few statistically significant effects are found outside the polar latitudes, and temperature effects over the non-polar oceans tend to be under 1 C, due in part to the specification of an unvarying annual cycle of sea surface temperatures. The +/- 7% and 14% results provide bounds on the impact (on GISS GCM simulations making use of satellite data) of satellite-derived ice concentration inaccuracies, +/- 7% being the current estimated average accuracy of satellite retrievals and +/- 4% being the anticipated improved average accuracy for upcoming satellite instruments. Results show that the impact on simulated temperatures of imposed ice concentration

  13. Evaluating regional climate models for simulating sub-daily rainfall extremes

    Science.gov (United States)

    Cortés-Hernández, Virginia Edith; Zheng, Feifei; Evans, Jason; Lambert, Martin; Sharma, Ashish; Westra, Seth

    2016-09-01

    Sub-daily rainfall extremes are of significant societal interest, with implications for flash flooding and the design of urban stormwater systems. It is increasingly recognised that extreme subdaily rainfall will intensify as a result of global temperature increases, with regional climate models (RCMs) representing one of the principal lines of evidence on the likely magnitude and spatiotemporal characteristics of these changes. To evaluate the ability of RCMs to simulate subdaily extremes, it is common to compare the simulated statistical characteristics of the extreme rainfall events with those from observational records. While such analyses are important, they provide insufficient insight into whether the RCM reproduces the correct underlying physical processes; in other words, whether the model "gets the right answers for the right reasons". This paper develops a range of metrics to assess the performance of RCMs in capturing the physical mechanisms that produce extreme rainfall. These metrics include the diurnal and seasonal cycles, relationship between rainfall intensity and temperature, temporal scaling, and the spatial structure of extreme rainfall events. We evaluate a high resolution RCM—the Weather Research Forecasting model—over the Greater Sydney region, using three alternative parametrization schemes. The model shows consistency with the observations for most of the proposed metrics. Where differences exist, these are dependent on both the rainfall duration and model parameterization strategy. The use of physically meaningful performance metrics not only enhances the confidence in model simulations, but also provides better diagnostic power to assist with future model improvement.

  14. Seasonal climate and air quality simulations for the northeastern US – Part 1: Model evaluation

    Directory of Open Access Journals (Sweden)

    H. Mao

    2009-09-01

    Full Text Available Regional climate and air quality simulations were conducted for summers 2001–2005 in the eastern US and subjected to extensive evaluation using various ground and airborne measurements. Climate evaluation focused on transport by comparing modeled dominant map types with ones from reanalysis. Reasonable agreement was found for their frequency of occurrence and distinctness of circulation patterns. The two most frequent map types from reanalysis were the Bermuda High (22% and passage of a Canadian cold frontal over the northeastern US (20%. The model captured their frequency of occurrence at 25% and 18% respectively. The simulated five average distributions of daily 1-h ozone (O3 daily maxima using the Community Multiscale Air Quality (CMAQ modeling system reproduced salient features in observations. This suggests that the ability of the regional climate model to depict transport processes accurately is critical for reasonable simulations of surface O3. Comparison of mean bias, root mean square error, and index of agreement for CMAQ summer surface 8-h O3 daily maxima and observations showed −0.6±14 nmol/mol, 14 nmol/mol, and 71% respectively. CMAQ performed best in moderately polluted conditions and less satisfactorily in highly polluted ones. This highlights the common problem of overestimating/underestimating lower/higher modeled O3 levels. Diagnostic analysis suggested that significant overestimation of inland nighttime low O3 mixing ratios may be attributed to underestimates of nitric oxide (NO emissions at night. The absence of the second daily peak in simulations for the Appledore Island marine site possibly resulted from coarse grid resolution misrepresentation of land surface type. Comparison with shipboard measurements suggested that CMAQ has an inherent problem of underpredicting O3 levels in continental outflow. Modeled O3 vertical profiles exhibited a

  15. Evaluation of the Regional Arctic System Model (RASM) - Process-resolving Arctic Climate Simulation

    Science.gov (United States)

    Maslowski, Wieslaw

    2016-04-01

    feedbacks will be discussed to emphasize the need for fully coupled climate model simulations, high model resolution and fine-tuning of many present parameterizations of sub-grid physical processes when changing model spatial resolution. We also investigate sensitivity of simulated sea ice states to scale dependence of model parameters controlling ice dynamics, thermodynamics and coupling with the atmosphere and ocean.

  16. Abrupt climate change and high to low latitude teleconnections as simulated in climate models

    DEFF Research Database (Denmark)

    Cvijanovic, Ivana

    of the present day atmospheric mid-latitude energy transport compared to that of the Last Glacial Maximum, suggesting its ability to reorganize more easily and thereby dampen high latitude temperature anomalies that could arise from changes in the oceanic transport. The role of tropical SSTs in the tropical......High to low latitude atmospheric teleconnections have been a topic of increasing scientific interest since it was shown that high latitude extratropical forcing can induce tropical precipitation shifts through atmosphere-surface ocean interactions. In this thesis, several aspects of high to low...... precipitation shifts was further re-examined in idealized simulations with the fixed tropical sea surface temperatures, showing that the SST changes are fundamental to the tropical precipitation shifts. Regarding the high latitude energy loss, it was shown that the main energy compensation comes from...

  17. Comparison of two bias correction methods for precipitation simulated with a regional climate model

    Science.gov (United States)

    Tschöke, Gabriele Vanessa; Kruk, Nadiane Smaha; de Queiroz, Paulo Ivo Braga; Chou, Sin Chan; de Sousa Junior, Wilson Cabral

    2017-02-01

    This study evaluates the performance of two bias correction techniques—power transformation and gamma distribution adjustment—for Eta regional climate model (RCM) precipitation simulations. For the gamma distribution adjustment, the number of dry days is not taken as a fixed parameter; rather, we propose a new methodology for handling dry days. We consider two cases: the first case is defined as having a greater number of simulated dry days than the observed number, and the second case is defined as the opposite. The present climate period was divided into calibration and validation sets. We evaluate the results of the two bias correction techniques using the Kolmogorov-Smirnov nonparametric test and the sum of the differences between the cumulative distribution curves. These tests show that both correction techniques were effective in reducing errors and consequently improving the reliability of the simulations. However, the gamma distribution correction method proved to be more efficient, particularly in reducing the error in the number of dry days.

  18. Impact of Land Use Change over North America as simulated by the Canadian Regional Climate Model

    Science.gov (United States)

    Chacon, A.; Sushama, L.; Beltrami, H.

    2014-12-01

    This study investigates the biogeophysical impacts of human-induced land cover change, particularly crops, on the regional climate of North America, using the fifth generation Canadian Regional Climate Model (CRCM5). To this effect, two simulations are performed with CRCM5 with different land cover datasets - one corresponding to the potential vegetation (i.e. without land use change) and the other corresponding to current land use. Most of the land use changes are concentrated over the US mid-west and south-central Canada, where forests and grasses have been replaced by crops. This transformation changes the surface parameters, particularly vegetation fractional area, leaf area index, albedo, roughness length and rooting depth among other variables, in the regions where land cover change takes place in these simulations. Both simulations span the 1988-2012 period and are driven by ERA-Interim at the lateral boundaries. The sea surface temperature and sea ice cover that vary inter-annually are also taken from ERA-Interim. Results suggest that regions where forests/grasses were replaced by crops generally show increases in albedo, particularly during the spring, fall and winter seasons, with the increase in albedo being largest for winter. This higher increase in albedo during winter is due to a snow-mediated positive feedback. The increased albedo values during winter, spring and fall are reflected in the cooler 2 meter temperature obtained in the simulation with land use change, compared to that with potential vegetation. Some cooling is observed in the summer for the simulation with land use change, mostly due to the increased latent heat fluxes. Increases in precipitation are noted for these regions, but are not statistically significant.

  19. Cross-scale intercomparison of climate change impacts simulated by regional and global hydrological models in eleven large river basins

    Energy Technology Data Exchange (ETDEWEB)

    Hattermann, F. F.; Krysanova, V.; Gosling, S. N.; Dankers, R.; Daggupati, P.; Donnelly, C.; Flörke, M.; Huang, S.; Motovilov, Y.; Buda, S.; Yang, T.; Müller, C.; Leng, G.; Tang, Q.; Portmann, F. T.; Hagemann, S.; Gerten, D.; Wada, Y.; Masaki, Y.; Alemayehu, T.; Satoh, Y.; Samaniego, L.

    2017-01-04

    Ideally, the results from models operating at different scales should agree in trend direction and magnitude of impacts under climate change. However, this implies that the sensitivity of impact models designed for either scale to climate variability and change is comparable. In this study, we compare hydrological changes simulated by 9 global and 9 regional hydrological models (HM) for 11 large river basins in all continents under reference and scenario conditions. The foci are on model validation runs, sensitivity of annual discharge to climate variability in the reference period, and sensitivity of the long-term average monthly seasonal dynamics to climate change. One major result is that the global models, mostly not calibrated against observations, often show a considerable bias in mean monthly discharge, whereas regional models show a much better reproduction of reference conditions. However, the sensitivity of two HM ensembles to climate variability is in general similar. The simulated climate change impacts in terms of long-term average monthly dynamics evaluated for HM ensemble medians and spreads show that the medians are to a certain extent comparable in some cases with distinct differences in others, and the spreads related to global models are mostly notably larger. Summarizing, this implies that global HMs are useful tools when looking at large-scale impacts of climate change and variability, but whenever impacts for a specific river basin or region are of interest, e.g. for complex water management applications, the regional-scale models validated against observed discharge should be used.

  20. Albedo and heat transport in 3-dimensional model simulations of the early Archean climate

    Directory of Open Access Journals (Sweden)

    H. Kienert

    2013-01-01

    Full Text Available At the beginning of the Archean eon (ca. 3.8 billion yr ago, the Earth's climate state was significantly different from today due to the lower solar luminosity, smaller continental fraction, higher rotation rate and, presumably, significantly larger greenhouse gas concentrations. All these aspects play a role in solutions to the "faint young Sun problem" which must explain why the ocean surface was not fully frozen at that time. Here, we present 3-dimensional model simulations of climate states that are consistent with early Archean boundary conditions and have different CO2 concentrations, aiming at an understanding of the fundamental characteristics of the early Archean climate system. We focus on three states: one of them is ice-free, one has the same mean surface air temperature of 288 K as today's Earth and the third one is the coldest stable state in which there is still an area with liquid surface water (i.e. the critical state at the transition to a "snowball Earth". We find a reduction in meridional heat transport compared to today which leads to a steeper latitudinal temperature profile and has atmospheric as well as oceanic contributions. Ocean surface velocities are largely zonal, and the strength of the atmospheric meridional circulation is significantly reduced in all three states. These aspects contribute to the observed relation between global mean temperature and albedo, which we suggest as a parameterisation of the ice-albedo feedback for 1-dimensional model simulations of the early Archean and thus the faint young Sun problem.

  1. Downscaling of general circulation model outputs: simulation of the snow climatology of the French Alps and sensitivity to climate change

    Energy Technology Data Exchange (ETDEWEB)

    Martin, E. [Centre Nat. de Recherches Meteorologiques Centre d`Etudes de la Neige, St. Martin d`Heres (France). Meteo-France; Timbal, B. [Groupe de Meteorologie a Grande Echelle et Climat, Toulouse (France); Brun, E. [Centre Nat. de Recherches Meteorologiques Centre d`Etudes de la Neige, St. Martin d`Heres (France). Meteo-France

    1996-12-01

    A downscaling method was developed to simulate the seasonal snow cover of the French Alps from general circulation model outputs under various scenarios. It consists of an analogue procedure, which associates a real meteorological situation to a model output. It is based on the comparison between simulated upper air fields and meteorological analyses from the European Centre for medium-range weather forecasts. The selection uses a nearest neighbour method at a daily time-step. In a second phase, the snow cover is simulated by the snow model CROCUS at several elevations and in the different regions of the French Alps by using data from the real meteorological situations. The method is tested with real data and applied to various ARPEGE/climate simulations: the present climate and two climate change scenarios. (orig.). With 10 figs., 4 tabs.

  2. Downscaling of general circulation model outputs: simulation of the snow climatology of the French Alps and sensitivity to climate change

    Science.gov (United States)

    Martin, E.; Timbal, B.; Brun, E.

    1996-12-01

    A downscaling method was developed to simulate the seasonal snow cover of the French Alps from general circulation model outputs under various scenarios. It consists of an analogue procedure, which associates a real meteorological situation to a model output. It is based on the comparison between simulated upper air fields and meteorological analyses from the European Centre for Medium-Range Weather Forecasts. The selection uses a nearest neighbour method at a daily time-step. In a second phase, the snow cover is simulated by the snow model CROCUS at several elevations and in the different regions of the French Alps by using data from the real meteorological situations. The method is tested with real data and applied to various ARPEGE/Climat simulations: the present climate and two climate change scenarios.

  3. [China's rice field greenhouse gas emission under climate change based on DNDC model simulation].

    Science.gov (United States)

    Tian, Zhan; Niu, Yi-long; Sun, Lai-xiang; Li, Chang-sheng; Liu, Chun-jiang; Fan, Dong-li

    2015-03-01

    In contrast to a large body of literature assessing the impact of agriculture greenhouse gas (GHG) emissions on climate change, there is a lack of research examining the impact of climate change on agricultural GHG emissions. This study employed the DNDC v9.5, a state-of-art biogeochemical model, to simulate greenhouse gas emissions in China' s rice-growing fields during 1971-2010. The results showed that owing to temperature rising (on average 0.49 °C higher in the second 20 years than in the first 20 year) and precipitation increase (11 mm more in the second 20 years than in the first 20 years) during the rice growing season, CH4 and N2O emissions in paddy field increased by 0.25 kg C . hm-2 and 0.25 kg N . hm-2, respectively. The rising temperature accelerated CH4 emission and N2O emission increased with precipitation. These results indicated that climate change exerted impact on the mechanism of GHG emissions in paddy field.

  4. The climate in China over the past 2000 years in a global Earth System Model simulation

    Science.gov (United States)

    Zorita, Eduardo; Wagner, Sebastian; Luterbacher, Jürg; Zhang, Huan

    2016-04-01

    The climate in China over the past 2000 years is analysed based on a global simulation with the Earth System Model MPI-ESM-P. This model has been used for the past millennium simulations of the Climate Model Intercomparison Project version 5. The model includes an atmospheric sub-model (ECHAM6), the ocean and sea-ice submodel MPI-OM. The carbon cycle and vegetation submodels of MPI-ESM-P were switched-off in the version of the Earth System Model. The climate model was forced by reconstructions of past volcanic activity, solar irradiance, greenhouse gases and land-use changes. Over the second millennium, these forcings are the same those used in the past-millennium CMIP5 simulations with the model MPI-ESM-P. For the first millennium, reconstructions of these forcings have been implemented, as described below. The reconstruction of the volcanic forcing is based on the sulphate data set of Sigl et al. (2013) and applying the algorithm of Crowley and Unterman (2012). The sulphate records are scaled to the Crowley and Unterman (2012) reconstruction used within CMIP5 in the second millennium. The solar forcing is based on the reconstruction of Vieira et al. (2011). Long-term changes represent a 0.1% difference between the Maunder Minimum (1645-1715 AD) and present-day values (1950-2000 AD). Land-use changes have been prescribed according to the CMIP5 protocol from 800 onwards and kept constant before this period. This global simulation is currently analysed, thus the presentation will show preliminary results on the past climate variations over China for the Common Era. The spatially averaged annual mean temperature clearly displays the known phases of a relatively warm Roman period, followed by colder conditions during the 'Dark Ages', warmer temperatures again during the Mediaeval Warm Period (MWP; peaking at about 1100 AD). The period from 1300 to 1800 was characterised by below normal temperatures. with an ensuing strong warming trend over approximately the last 200

  5. CIELO-A GIS integrated model for climatic and water balance simulation in islands environments

    Science.gov (United States)

    Azevedo, E. B.; Pereira, L. S.

    2003-04-01

    The model CIELO (acronym for "Clima Insular à Escala Local") is a physically based model that simulates the climatic variables in an island using data from a single synoptic reference meteorological station. The reference station "knows" its position in the orographic and dynamic regime context. The domain of computation is a GIS raster grid parameterised with a digital elevation model (DEM). The grid is oriented following the direction of the air masses circulation through a specific algorithm named rotational terrain model (RTM). The model consists of two main sub-models. One, relative to the advective component simulation, assumes the Foehn effect to reproduce the dynamic and thermodynamic processes occurring when an air mass moves through the island orographic obstacle. This makes possible to simulate the air temperature, air humidity, cloudiness and precipitation as influenced by the orography along the air displacement. The second concerns the radiative component as affected by the clouds of orographic origin and by the shadow produced by the relief. The initial state parameters are computed starting from the reference meteorological station across the DEM transept until the sea level at the windward side. Then, starting from the sea level, the model computes the local scale meteorological parameters according to the direction of the air displacement, which is adjusted with the RTM. The air pressure, temperature and humidity are directly calculated for each cell in the computational grid, while several algorithms are used to compute the cloudiness, net radiation, evapotranspiration, and precipitation. The model presented in this paper has been calibrated and validated using data from some meteorological stations and a larger number of rainfall stations located at various elevations in the Azores Islands.

  6. MODFLOW datasets for simulations of groundwater flow with downscaled global climate model data for the Suwannee River Basin, Florida

    Science.gov (United States)

    Swain, Eric D.; Davis, J. Hal

    2016-01-01

    A previously-developed groundwater model of the Suwannee River Basin was modified and calibrated to represent transient conditions. A simulation of recent conditions was developed for the 372-month period 1970-2000, and was compared with a simulation of future conditions for a similar-length period 2039-2069, which uses downscaled GCM (Global Climate Model) data. The MODFLOW groundwater-simulation code was used in both of these simulations, and two different MODFLOW boundary condition “packages” (River and Streamflow Routing Packages) were used to represent interactions between surface-water and groundwater features. The parameters for the simulation of future conditions were developed from dynamically downscaled precipitation and evapotranspiration data generated by the Community Climate System Model. The model was developed to examine the effect of downscaled climate model data on the predictions of future hydrology in the Suwannee River Basin. The development of the model input and output files included in this data release are documented in a journal article for the American Journal of Climate Change. Support is provided for correcting errors in the data release and clarification of the modeling conducted by the U.S. Geological Survey. Users are encouraged to review the model documentation report to understand the purpose, construction, and limitations of this model.

  7. Simulation of heat waves in climate models using large deviation algorithms

    Science.gov (United States)

    Ragone, Francesco; Bouchet, Freddy; Wouters, Jeroen

    2016-04-01

    One of the goals of climate science is to characterize the statistics of extreme, potentially dangerous events (e.g. exceptionally intense precipitations, wind gusts, heat waves) in the present and future climate. The study of extremes is however hindered by both a lack of past observational data for events with a return time larger than decades or centuries, and by the large computational cost required to perform a proper sampling of extreme statistics with state of the art climate models. The study of the dynamics leading to extreme events is especially difficult as it requires hundreds or thousands of realizations of the dynamical paths leading to similar extremes. We will discuss here a new numerical algorithm, based on large deviation theory, that allows to efficiently sample very rare events in complex climate models. A large ensemble of realizations are run in parallel, and selection and cloning procedures are applied in order to oversample the trajectories leading to the extremes of interest. The statistics and characteristic dynamics of the extremes can then be computed on a much larger sample of events. This kind of importance sampling method belongs to a class of genetic algorithms that have been successfully applied in other scientific fields (statistical mechanics, complex biomolecular dynamics), allowing to decrease by orders of magnitude the numerical cost required to sample extremes with respect to standard direct numerical sampling. We study the applicability of this method to the computation of the statistics of European surface temperatures with the Planet Simulator (Plasim), an intermediate complexity general circulation model of the atmosphere. We demonstrate the efficiency of the method by comparing its performances against standard approaches. Dynamical paths leading to heat waves are studied, enlightening the relation of Plasim heat waves with blocking events, and the dynamics leading to these events. We then discuss the feasibility of this

  8. Large-scale atmospheric circulation biases and changes in global climate model simulations and their importance for climate change in Central Europe

    Directory of Open Access Journals (Sweden)

    A. P. van Ulden

    2006-01-01

    Full Text Available The quality of global sea level pressure patterns has been assessed for simulations by 23 coupled climate models. Most models showed high pattern correlations. With respect to the explained spatial variance, many models showed serious large-scale deficiencies, especially at mid-latitudes. Five models performed well at all latitudes and for each month of the year. Three models had a reasonable skill. We selected the five models with the best pressure patterns for a more detailed assessment of their simulations of the climate in Central Europe. We analysed observations and simulations of monthly mean geostrophic flow indices and of monthly mean temperature and precipitation. We used three geostrophic flow indices: the west component and south component of the geostrophic wind at the surface and the geostrophic vorticity. We found that circulation biases were important, and affected precipitation in particular. Apart from these circulation biases, the models showed other biases in temperature and precipitation, which were for some models larger than the circulation induced biases. For the 21st century the five models simulated quite different changes in circulation, precipitation and temperature. Precipitation changes appear to be primarily caused by circulation changes. Since the models show widely different circulation changes, especially in late summer, precipitation changes vary widely between the models as well. Some models simulate severe drying in late summer, while one model simulates significant precipitation increases in late summer. With respect to the mean temperature the circulation changes were important, but not dominant. However, changes in the distribution of monthly mean temperatures, do show large indirect influences of circulation changes. Especially in late summer, two models simulate very strong warming of warm months, which can be attributed to severe summer drying in the simulations by these models. The models differ also

  9. Greenland ice sheet surface mass balance: evaluating simulations and making projections with regional climate models

    Directory of Open Access Journals (Sweden)

    J. G. L. Rae

    2012-06-01

    Full Text Available Four high-resolution regional climate models (RCMs have been set up for the area of Greenland, with the aim of providing future projections of Greenland ice sheet surface mass balance (SMB, and its contribution to sea level rise, with greater accuracy than is possible from coarser-resolution general circulation models (GCMs. This is the first time an intercomparison has been carried out of RCM results for Greenland climate and SMB. Output from RCM simulations for the recent past with the four RCMs is evaluated against available observations. The evaluation highlights the importance of using a detailed snow physics scheme, especially regarding the representations of albedo and meltwater refreezing. Simulations with three of the RCMs for the 21st century using SRES scenario A1B from two GCMs produce trends of between −5.5 and −1.1 Gt yr−2 in SMB (equivalent to +0.015 and +0.003 mm sea level equivalent yr−2, with trends of smaller magnitude for scenario E1, in which emissions are mitigated. Results from one of the RCMs whose present-day simulation is most realistic indicate that an annual-mean near-surface air temperature increase over Greenland of ~2 C would be required for the mass loss to increase such that it exceeds accumulation, thereby causing the SMB to become negative, which has been suggested as a threshold beyond which the ice-sheet would eventually be eliminated.

  10. Greenland ice sheet surface mass balance: evaluating simulations and making projections with regional climate models

    Directory of Open Access Journals (Sweden)

    J. G. L. Rae

    2012-11-01

    Full Text Available Four high-resolution regional climate models (RCMs have been set up for the area of Greenland, with the aim of providing future projections of Greenland ice sheet surface mass balance (SMB, and its contribution to sea level rise, with greater accuracy than is possible from coarser-resolution general circulation models (GCMs. This is the first time an intercomparison has been carried out of RCM results for Greenland climate and SMB. Output from RCM simulations for the recent past with the four RCMs is evaluated against available observations. The evaluation highlights the importance of using a detailed snow physics scheme, especially regarding the representations of albedo and meltwater refreezing. Simulations with three of the RCMs for the 21st century using SRES scenario A1B from two GCMs produce trends of between −5.5 and −1.1 Gt yr−2 in SMB (equivalent to +0.015 and +0.003 mm sea level equivalent yr−2, with trends of smaller magnitude for scenario E1, in which emissions are mitigated. Results from one of the RCMs whose present-day simulation is most realistic indicate that an annual mean near-surface air temperature increase over Greenland of ~ 2°C would be required for the mass loss to increase such that it exceeds accumulation, thereby causing the SMB to become negative, which has been suggested as a threshold beyond which the ice sheet would eventually be eliminated.

  11. Changes in Intense Rainfall Events over the Central United States in AOGCM-Driven Regional Climate Model Simulations

    Science.gov (United States)

    Daniel, A. R.; Arritt, R. W.; Groisman, P. Y.

    2014-12-01

    We have evaluated trends in extreme precipitation frequency for the central United States (Groisman et al. 2012) using atmosphere-ocean global climate model (AOGCM) driven regional climate simulations. Nested regional climate model simulations were conducted using RegCM4.4 over the CORDEX-North America domain with 50 km grid spacing. Initial and lateral boundary conditions are taken from the HadGEM2-ES and GFDL-ESM2M AOGCMs (for RCP8.5 emissions scenario) to simulate present and future climate (1951-2098). For each run, RegCM4 uses three different convection schemes: Emanuel scheme, Grell scheme, and Mixed scheme which uses the Emanuel scheme over water and Grell over land.Current findings show the regional climate simulations are of the same magnitude of average frequency for heavy ( 25.4-76.2 mm/day), and extreme (154.9+ mm/day) precipitation events while very heavy events (76.2+ mm/day) were less frequent by an order of magnitude. For current and recent past climate (1951-2005), frequency of precipitation events is similar in both HadGEM2-ES and GFDL-ESM2M AOGCM-driven regional climate simulations with most variation due to the convection scheme being used. Initial results seem to exhibit similar trends in the increase of frequency for each precipitation event as is seen in observations. In accordance with Groisman et al. (2012), preliminary findings also show months during the cold season had more frequent heavy events in comparison to very heavy and extreme events while months during the warm season had more frequent very heavy and extreme events in comparison to heavy events. Further analysis will better determine the correlation and accuracy of these regional climate simulations.

  12. Evaluation of Continental Precipitation in 20th-Century Climate Simulations: The Utility of Multi-Model Statistics

    Energy Technology Data Exchange (ETDEWEB)

    Phillips, T J; Gleckler, P J

    2005-11-01

    At the request of the Intergovernmental Panel on Climate Change (IPCC), simulations of 20th-century climate have been performed recently with some 20 global coupled ocean-atmosphere models. In view of its central importance for biological and socio-economic systems, model-simulated continental precipitation is evaluated relative to three observational estimates at both global and regional scales. Many models are found to display systematic biases, deviating markedly from the observed spatial variability and amplitude/phase of the seasonal cycle. However, the point-wise ensemble mean of all the models usually shows better statistical agreement with the observations than does any single model. Deficiencies of current models that may be responsible for the simulated precipitation biases as well as possible reasons for the improved estimate afforded by the multi-model ensemble mean are discussed. Implications of these results for water-resource managers also are briefly addressed.

  13. First synchronous realistic simulations of Antarctic and Greenland SMB in a fully coupled climate model

    Science.gov (United States)

    Lenaerts, J.; van Kampenhout, L.; Lipscomb, W. H.; Gettelman, A.; van den Broeke, M.; Sacks, W.; Fyke, J. G.; Vizcaino, M.; Löfverström, M.

    2015-12-01

    Here we use the global, coupled ocean-atmosphere-land Community Earth System Model (CESM) at a 1o degree horizontal resolution to simulate recent past (1850-now) and future (21st century) Greenland and Antarctic ice sheet SMB in tandem. To that end, we have recently improved the representation of firn in CESM. We increased the vertical thickness of snow, which enhances the buffering of meltwater through refreezing, and firn density, to allow for wind-induced snow compaction. Other model improvements focused on atmospheric clouds; the most recent CESM atmosphere model allows for more liquid water in clouds, which increases positive longwave cloud forcing, and has profound and beneficial impact on the ice sheet surface radiation balance. In this contribution, we will show that the above improvements enable a realistic CESM simulation of both Greenland and Antarctic SMB. This allows for analysis of future evolution of ice sheet SMB and the interactions between ice sheets and other components of the climate system.

  14. Future changes in extreme precipitation in the Rhine basin based on global and regional climate model simulations

    Directory of Open Access Journals (Sweden)

    S. C. van Pelt

    2012-12-01

    Full Text Available Probability estimates of the future change of extreme precipitation events are usually based on a limited number of available global climate model (GCM or regional climate model (RCM simulations. Since floods are related to heavy precipitation events, this restricts the assessment of flood risks. In this study a relatively simple method has been developed to get a better description of the range of changes in extreme precipitation events. Five bias-corrected RCM simulations of the 1961–2100 climate for a single greenhouse gas emission scenario (A1B SRES were available for the Rhine basin. To increase the size of this five-member RCM ensemble, 13 additional GCM simulations were analysed. The climate responses of the GCMs are used to modify an observed (1961–1995 precipitation time series with an advanced delta change approach. Changes in the temporal means and variability are taken into account. It is found that the range of future change of extreme precipitation across the five-member RCM ensemble is similar to results from the 13-member GCM ensemble. For the RCM ensemble, the time series modification procedure also results in a similar climate response compared to the signal deduced from the direct model simulations. The changes from the individual RCM simulations, however, systematically differ from those of the driving GCMs, especially for long return periods.

  15. An efficient regional energy-moisture balance model for simulation of the Greenland Ice Sheet response to climate change

    Directory of Open Access Journals (Sweden)

    A. Robinson

    2010-04-01

    Full Text Available In order to explore the response of the Greenland ice sheet (GIS to climate change on long (centennial to multi-millennial time scales, a regional energy-moisture balance model has been developed. This model simulates seasonal variations of temperature and precipitation over Greenland and explicitly accounts for elevation and albedo feedbacks. From these fields, the annual mean surface temperature and surface mass balance can be determined and used to force an ice sheet model. The melt component of the surface mass balance is computed here using both a positive degree day approach and a more physically-based alternative that includes insolation and albedo explicitly. As a validation of the climate model, we first simulated temperature and precipitation over Greenland for the prescribed, present-day topography. Our simulated climatology compares well to observations and does not differ significantly from that of a simple parameterization used in many previous simulations. Furthermore, the calculated surface mass balance using both melt schemes falls within the range of recent regional climate model results. For a prescribed, ice-free state, the differences in simulated climatology between the regional energy-moisture balance model and the simple parameterization become significant, with our model showing much stronger summer warming. When coupled to a three-dimensional ice sheet model and initialized with present-day conditions, the two melt schemes both allow realistic simulations of the present-day GIS.

  16. Errors and uncertainties introduced by a regional climate model in climate impact assessments: example of crop yield simulations in West Africa

    Science.gov (United States)

    Ramarohetra, Johanna; Pohl, Benjamin; Sultan, Benjamin

    2015-12-01

    The challenge of estimating the potential impacts of climate change has led to an increasing use of dynamical downscaling to produce fine spatial-scale climate projections for impact assessments. In this work, we analyze if and to what extent the bias in the simulated crop yield can be reduced by using the Weather Research and Forecasting (WRF) regional climate model to downscale ERA-Interim (European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis) rainfall and radiation data. Then, we evaluate the uncertainties resulting from both the choice of the physical parameterizations of the WRF model and its internal variability. Impact assessments were performed at two sites in Sub-Saharan Africa and by using two crop models to simulate Niger pearl millet and Benin maize yields. We find that the use of the WRF model to downscale ERA-Interim climate data generally reduces the bias in the simulated crop yield, yet this reduction in bias strongly depends on the choices in the model setup. Among the physical parameterizations considered, we show that the choice of the land surface model (LSM) is of primary importance. When there is no coupling with a LSM, or when the LSM is too simplistic, the simulated precipitation and then the simulated yield are null, or respectively very low; therefore, coupling with a LSM is necessary. The convective scheme is the second most influential scheme for yield simulation, followed by the shortwave radiation scheme. The uncertainties related to the internal variability of the WRF model are also significant and reach up to 30% of the simulated yields. These results suggest that regional models need to be used more carefully in order to improve the reliability of impact assessments.

  17. Spatial-Scale Characteristics of Precipitation Simulated by Regional Climate Models and the Implications for Hydrological Modeling

    DEFF Research Database (Denmark)

    Rasmussen, S.H.; Christensen, J. H.; Drews, Martin;

    2012-01-01

    , reflecting larger predictive certainty of the RCMs at larger scales. The findings on aggregated grid scales are shown to be largely independent of the underlying RCMs grid resolutions but not of the overall size of RCM domain. With regard to hydrological modeling applications, these findings indicate......Precipitation simulated by regional climate models (RCMs) is generally biased with respect to observations, especially at the local scale of a few tens of kilometers. This study investigates how well two different RCMs are able to reproduce the spatial correlation patterns of observed summer...

  18. A Hierarchical Evaluation of Regional Climate Simulations

    Energy Technology Data Exchange (ETDEWEB)

    Leung, Lai-Yung R.; Ringler, Todd; Collins, William D.; Taylor, Mark; Ashfaq, Moetasim

    2013-08-20

    Global climate models (GCMs) are the primary tools for predicting the evolution of the climate system. Through decades of development, GCMs have demonstrated useful skill in simulating climate at continental to global scales. However, large uncertainties remain in projecting climate change at regional scales, which limit our ability to inform decisions on climate change adaptation and mitigation. To bridge this gap, different modeling approaches including nested regional climate models (RCMs), global stretch-grid models, and global high-resolution atmospheric models have been used to provide regional climate simulations (Leung et al. 2003). In previous efforts to evaluate these approaches, isolating their relative merits was not possible because factors such as dynamical frameworks, physics parameterizations, and model resolutions were not systematically constrained. With advances in high performance computing, it is now feasible to run coupled atmosphere-ocean GCMs at horizontal resolution comparable to what RCMs use today. Global models with local refinement using unstructured grids have become available for modeling regional climate (e.g., Rauscher et al. 2012; Ringler et al. 2013). While they offer opportunities to improve climate simulations, significant efforts are needed to test their veracity for regional-scale climate simulations.

  19. Effects of elevated CO2 and drought on wheat : testing crop simulation models for different experimental and climatic conditions

    NARCIS (Netherlands)

    Ewert, F.; Rodriguez, D.; Jamieson, P.; Semenov, M.A.; Mitchell, R.A.C.; Goudriaan, J.; Porter, J.R.; Kimball, B.A.; Pinter, P.J.; Manderscheid, R.; Weigel, H.J.; Fangmeier, A.; Fereres, E.; Villalobos, F.

    2002-01-01

    Effects of increasing carbon dioxide concentration [CO2] on wheat vary depending on water supply and climatic conditions, which are difficult to estimate. Crop simulation models are often used to predict the impact of global atmospheric changes on food production. However, models have rarely been te

  20. Coupled climate model simulations of Mediterranean winter cyclones and large-scale flow patterns

    Directory of Open Access Journals (Sweden)

    B. Ziv

    2013-03-01

    Full Text Available The study aims to evaluate the ability of global, coupled climate models to reproduce the synoptic regime of the Mediterranean Basin. The output of simulations of the 9 models included in the IPCC CMIP3 effort is compared to the NCEP-NCAR reanalyzed data for the period 1961–1990. The study examined the spatial distribution of cyclone occurrence, the mean Mediterranean upper- and lower-level troughs, the inter-annual variation and trend in the occurrence of the Mediterranean cyclones, and the main large-scale circulation patterns, represented by rotated EOFs of 500 hPa and sea level pressure. The models reproduce successfully the two maxima in cyclone density in the Mediterranean and their locations, the location of the average upper- and lower-level troughs, the relative inter-annual variation in cyclone occurrences and the structure of the four leading large scale EOFs. The main discrepancy is the models' underestimation of the cyclone density in the Mediterranean, especially in its western part. The models' skill in reproducing the cyclone distribution is found correlated with their spatial resolution, especially in the vertical. The current improvement in model spatial resolution suggests that their ability to reproduce the Mediterranean cyclones would be improved as well.

  1. CMIP5 model simulations of Ethiopian Kiremt-season precipitation: current climate and future changes

    Science.gov (United States)

    Li, Laifang; Li, Wenhong; Ballard, Tristan; Sun, Ge; Jeuland, Marc

    2016-05-01

    Kiremt-season (June-September) precipitation provides a significant water supply for Ethiopia, particularly in the central and northern regions. The response of Kiremt-season precipitation to climate change is thus of great concern to water resource managers. However, the complex processes that control Kiremt-season precipitation challenge the capability of general circulation models (GCMs) to accurately simulate precipitation amount and variability. This in turn raises questions about their utility for predicting future changes. This study assesses the impact of climate change on Kiremt-season precipitation using state-of-the-art GCMs participating in the Coupled Model Intercomparison Project Phase 5. Compared to models with a coarse resolution, high-resolution models (horizontal resolution RCP) 4.5 scenario, these high-resolution models project an increase in precipitation over central Highlands and northern Great Rift Valley in Ethiopia, but a decrease in precipitation over the southern part of the country. Such a dipole pattern is attributable to the intensification of the North Atlantic subtropical high (NASH) in a warmer climate, which influences Ethiopian Kiremt-season precipitation mainly by modulating atmospheric vertical motion. Diagnosis of the omega equation demonstrates that an intensified NASH increases (decreases) the advection of warm air and positive vorticity into the central Highlands and northern Great Rift Valley (southern part of the country), enhancing upward motion over the northern Rift Valley but decreasing elsewhere. Under the RCP 4.5 scenario, the high-resolution models project an intensification of the NASH by 15 (3 × 105 m2 s-2) geopotential meters (stream function) at the 850-hPa level, contributing to the projected precipitation change over Ethiopia. The influence of the NASH on Kiremt-season precipitation becomes more evident in the future due to the offsetting effects of two other major circulation systems: the East African Low

  2. Simulating river discharge in a snowy region of Japan using output from a regional climate model

    Science.gov (United States)

    Ma, X.; Kawase, H.; Adachi, S.; Fujita, M.; Takahashi, H. G.; Hara, M.; Ishizaki, N.; Yoshikane, T.; Hatsushika, H.; Wakazuki, Y.; Kimura, F.

    2013-07-01

    Snowfall amounts have fallen sharply along the eastern coast of the Sea of Japan since the mid-1980s. Toyama Prefecture, located approximately in the center of the Japan Sea region, includes high mountains of the northern Japanese Alps on three of its sides. The scarcity of meteorological observation points in mountainous areas limits the accuracy of hydrological analysis. With the development of computing technology, a dynamical downscaling method is widely applied into hydrological analysis. In this study, we numerically modeled river discharge using runoff data derived by a regional climate model (4.5-km spatial resolution) as input data to river networks (30-arcseconds resolution) for the Toyama Prefecture. The five main rivers in Toyama (the Oyabe, Sho, Jinzu, Joganji, and Kurobe rivers) were selected in this study. The river basins range in area from 368 to 2720 km2. A numerical experiment using climate comparable to that at present was conducted for the 1980s and 1990s. The results showed that seasonal river discharge could be represented and that discharge was generally overestimated compared with measurements, except for Oyabe River discharge, which was always underestimated. The average correlation coefficient for 10-year average monthly mean discharge was 0.8, with correlation coefficients ranging from 0.56 to 0.88 for all five rivers, whereas the Nash-Sutcliffe efficiency coefficient indicated that the simulation accuracy was insufficient. From the water budget analysis, it was possible to speculate that the lack of accuracy of river discharge may be caused by insufficient accuracy of precipitation simulation.

  3. Testing the ability of RIEMS2.0 (Regional Integrated Environment Modeling System) on regional climate simulation in East Asia

    Science.gov (United States)

    Zhao, D.; Fu, C.; Yan, X.

    2010-12-01

    RIEMS1.0 (Regional Integrated Environmental Modeling System version 1.0) was developed by researchers from the START (Global change System for Analysis, Research, and Training) Regional Center for Temperate East Asia, IAP/CAS in 1998. The model was built on the thermodynamic frame of PSU/NCAR MM5V2, into which a land surface scheme (BATS1e) and radiative transfer scheme (the revised CCM3) are integrated. The model has been widely used in regional climate studies in the East Asia monsoon system and expresses excellent performance from RMIP (Regional Climate Model Inter-comparison Project). RIEMS2.0 is now being developed starting from RIEMS1.0 by the Key Laboratory of Regional Climate Environment Research for Temperate East Asia, IAP/CAS, and Nanjing University. The new version is built on the thermodynamic framework of nonhydrostatic approximation from MM5V3 with the same land surface model and radiation scheme as RIEMS1.0. To make it an integrated modeling system, the Princeton ocean mode (POM), Atmosphere-Vegetation interaction model (AVIM) and a chemical model are now being integrated. In order to test RIEMS2.0’s ability to simulate short-term climate, we perform ensemble simulations with different physics process schemes. The model will be used to perform ensemble simulations on two continuous extreme climate events, which is serve drought with high temperature in north China in the summer (June, July and August) of 1997 and serve flood in the Yangtze River valley in the summer of 1998. The results show that RIEMS2.0 can reproduce the spatial distribution of the precipitation and SAT from two continuous extreme climate events in the summer of 1997/1998, and disclose sub-regional characteristics. Though difference can be found among ensemble members, ensembles can decrease the model’s uncertainty and improve the simulation decision in a certain degree. In order to test RIEMS2.0’s ability to simulate long-term climate and climate change, we compare

  4. Antarctic ozone depletion between 1960 and 1980 in observations and chemistry-climate model simulations

    Science.gov (United States)

    Langematz, Ulrike; Schmidt, Franziska; Kunze, Markus; Bodeker, Gregory E.; Braesicke, Peter

    2016-12-01

    The year 1980 has often been used as a benchmark for the return of Antarctic ozone to conditions assumed to be unaffected by emissions of ozone-depleting substances (ODSs), implying that anthropogenic ozone depletion in Antarctica started around 1980. Here, the extent of anthropogenically driven Antarctic ozone depletion prior to 1980 is examined using output from transient chemistry-climate model (CCM) simulations from 1960 to 2000 with prescribed changes of ozone-depleting substance concentrations in conjunction with observations. A regression model is used to attribute CCM modelled and observed changes in Antarctic total column ozone to halogen-driven chemistry prior to 1980. Wintertime Antarctic ozone is strongly affected by dynamical processes that vary in amplitude from year to year and from model to model. However, when the dynamical and chemical impacts on ozone are separated, all models consistently show a long-term, halogen-induced negative trend in Antarctic ozone from 1960 to 1980. The anthropogenically driven ozone loss from 1960 to 1980 ranges between 26.4 ± 3.4 and 49.8 ± 6.2 % of the total anthropogenic ozone depletion from 1960 to 2000. An even stronger ozone decline of 56.4 ± 6.8 % was estimated from ozone observations. This analysis of the observations and simulations from 17 CCMs clarifies that while the return of Antarctic ozone to 1980 values remains a valid milestone, achieving that milestone is not indicative of full recovery of the Antarctic ozone layer from the effects of ODSs.

  5. Multiyear simulation of the African climate using a regional climate model (RegCM3) with the high resolution ERA-interim reanalysis

    Energy Technology Data Exchange (ETDEWEB)

    Sylla, Mouhamadou Bamba [Cheikh Anta Diop University, Laboratory for Atmospheric Physics, Simeon Fongang (LPASF), Polytechnic School, BP 5085, Dakar (Senegal); Coppola, E.; Giorgi, F.; Bi, X. [International Centre for Theoretical Physics (ICTP), Physics of Weather and Climate Group, Earth System Physics Section, Trieste (Italy); Mariotti, L. [International Centre for Theoretical Physics (ICTP), Physics of Weather and Climate Group, Earth System Physics Section, Trieste (Italy); University of L' Aquila, Department of Physics, Centre of Excellence CETEMPS, L' Aquila (Italy); Ruti, P.M.; Dell' Aquila, A. [Casaccia Center, Ente per le Nuove Technologie, l' Energia e l' Ambiente (ENEA), Climate Section, Rome (Italy)

    2010-07-15

    This study examines the ability of the latest version of the International Centre for Theoretical Physics (ICTP) regional climate model (RegCM3) to reproduce seasonal mean climatologies, annual cycle and interannual variability over the entire African continent and different climate subregions. The new European Center for Medium Range Weather Forecast (ECMWF) ERA-interim reanalysis is used to provide initial and lateral boundary conditions for the RegCM3 simulation. Seasonal mean values of zonal wind profile, temperature, precipitation and associated low level circulations are shown to be realistically simulated, although the regional model still shows some deficiencies. The West Africa monsoon flow is somewhat overestimated and the Africa Easterly Jet (AEJ) core intensity is underestimated. Despite these biases, there is a marked improvement in these simulated model variables compared to previous applications of this model over Africa. The mean annual cycle of precipitation, including single and multiple rainy seasons, is well captured over most African subregions, in some cases even improving the quality of the ERA-interim reanalysis. Similarly, the observed precipitation interannual variability is well reproduced by the regional model over most regions, mostly following, and sometimes improving, the quality of the ERA-interim reanalysis. It is assessed that the performance of this model over the entire African domain is of sufficient quality for application to the study of climate change and climate variability over the African continent. (orig.)

  6. Cross - Scale Intercomparison of Climate Change Impacts Simulated by Regional and Global Hydrological Models in Eleven Large River Basins

    Science.gov (United States)

    Hattermann, F. F.; Krysanova, V.; Gosling, S. N.; Dankers, R.; Daggupati, P.; Donnelly, C.; Florke, M.; Huang, S.; Motovilov, Y.; Buda, S.; Wada, Y.

    2017-01-01

    Ideally, the results from models operating at different scales should agree in trend direction and magnitude of impacts under climate change. However, this implies that the sensitivity to climate variability and climate change is comparable for impact models designed for either scale. In this study, we compare hydrological changes simulated by 9 global and 9 regional hydrological models (HM) for 11 large river basins in all continents under reference and scenario conditions. The foci are on model validation runs, sensitivity of annual discharge to climate variability in the reference period, and sensitivity of the long-term average monthly seasonal dynamics to climate change. One major result is that the global models, mostly not calibrated against observations, often show a considerable bias in mean monthly discharge, whereas regional models show a better reproduction of reference conditions. However, the sensitivity of the two HM ensembles to climate variability is in general similar. The simulated climate change impacts in terms of long-term average monthly dynamics evaluated for HM ensemble medians and spreads show that the medians are to a certain extent comparable in some cases, but have distinct differences in other cases, and the spreads related to global models are mostly notably larger. Summarizing, this implies that global HMs are useful tools when looking at large-scale impacts of climate change and variability. Whenever impacts for a specific river basin or region are of interest, e.g. for complex water management applications, the regional-scale models calibrated and validated against observed discharge should be used.

  7. GFDL's ESM2 global coupled climate-carbon Earth System Models. Part I: physical formulation and baseline simulation characteristics

    Science.gov (United States)

    Dunne, John P.; John, Jasmin G.; Adcroft, Alistair J.; Griffies, Stephen M.; Hallberg, Robert W.; Shevalikova, Elena; Stouffer, Ronald J.; Cooke, William; Dunne, Krista A.; Harrison, Matthew J.; Krasting, John P.; Malyshev, Sergey L.; Milly, P.C.D.; Phillipps, Peter J.; Sentman, Lori A.; Samuels, Bonita L.; Spelman, Michael J.; Winton, Michael; Wittenberg, Andrew T.; Zadeh, Niki

    2012-01-01

    We describe the physical climate formulation and simulation characteristics of two new global coupled carbon-climate Earth System Models, ESM2M and ESM2G. These models demonstrate similar climate fidelity as the Geophysical Fluid Dynamics Laboratory's previous CM2.1 climate model while incorporating explicit and consistent carbon dynamics. The two models differ exclusively in the physical ocean component; ESM2M uses Modular Ocean Model version 4.1 with vertical pressure layers while ESM2G uses Generalized Ocean Layer Dynamics with a bulk mixed layer and interior isopycnal layers. Differences in the ocean mean state include the thermocline depth being relatively deep in ESM2M and relatively shallow in ESM2G compared to observations. The crucial role of ocean dynamics on climate variability is highlighted in the El Niño-Southern Oscillation being overly strong in ESM2M and overly weak ESM2G relative to observations. Thus, while ESM2G might better represent climate changes relating to: total heat content variability given its lack of long term drift, gyre circulation and ventilation in the North Pacific, tropical Atlantic and Indian Oceans, and depth structure in the overturning and abyssal flows, ESM2M might better represent climate changes relating to: surface circulation given its superior surface temperature, salinity and height patterns, tropical Pacific circulation and variability, and Southern Ocean dynamics. Our overall assessment is that neither model is fundamentally superior to the other, and that both models achieve sufficient fidelity to allow meaningful climate and earth system modeling applications. This affords us the ability to assess the role of ocean configuration on earth system interactions in the context of two state-of-the-art coupled carbon-climate models.

  8. Climate Variability and Weather Extremes: Model-Simulated and Historical Data. Chapter 9

    Science.gov (United States)

    Schubert, Siegfried D.; Lim, Young-Kwon

    2012-01-01

    basic mechanisms by which extremes vary is incomplete. As noted in IPCC (2007), Incomplete global data sets and remaining model uncertainties still restrict understanding of changes in extremes and attribution of changes to causes, although understanding of changes in the intensity, frequency and risk of extremes has improved. Separating decadal and other shorter-term variability from climate change impacts on extremes requires a better understanding of the processes responsible for the changes. In particular, the physical processes linking sea surface temperature changes to regional climate changes, and a basic understanding of the inherent variability in weather extremes and how that is impacted by atmospheric circulation changes at subseasonal to decadal and longer time scales, are still inadequately understood. Given the fundamental limitations in the time span and quality of global observations, substantial progress on these issues will rely increasingly on improvements in models, with observations continuing to play a critical role, though less as a detection tool, and more as a tool for addressing physical processes, and to insure the quality of the climate models and the verisimilitude of the simulations (CCSP SAP 1.3, 2008).

  9. Improved confidence in regional climate model simulations of precipitation evaluated using drought statistics from the ENSEMBLES models

    Science.gov (United States)

    Maule, Cathrine Fox; Thejll, Peter; Christensen, Jens H.; Svendsen, Synne H.; Hannaford, Jamie

    2013-01-01

    An ensemble of regional climate model simulations from the European framework project ENSEMBLES is compared with observations of low precipitation events across a number of European regions. We characterize precipitation deficits in terms of two drought indices, the Standardized Precipitation Index and the self-calibrated Palmer Drought Severity Index. Models that robustly describe the observations for the period 1961-2000 in given regions are identified and an assessment of the overall performance of the ensemble is provided. The results show that in general, models capture the most severe drought events and that the ensemble mean model also performs well. Some regions that appear to be more problematic to simulate well are also identified. These are relatively small regions and have rather complex topographical features. The analysis suggests that assessment of future drought occurrence based on climate change experiments in general would appear to be robust. But due to the heterogeneous and often fine-scaled structure of drought occurrence, quantitative results should be used with great care, particularly in regions with complex terrain and limited information about past drought occurrence.

  10. The carbon cycle in the Australian Community Climate and Earth System Simulator (ACCESS-ESM1) - Part 1: Model description and pre-industrial simulation

    Science.gov (United States)

    Law, R. M.; Ziehn, T.; Matear, R. J.; Lenton, A.; Chamberlain, M. A.; Stevens, L. E.; Wang, Y. P.; Srbinovsky, J.; Bi, D.; Yan, H.; Vohralik, P. F.

    2015-09-01

    Earth System Models (ESMs) that incorporate carbon-climate feedbacks represent the present state of the art in climate modelling. Here, we describe the Australian Community Climate and Earth System Simulator (ACCESS)-ESM1 that combines existing ocean and land carbon models into the physical climate model to simulate exchanges of carbon between the land, atmosphere and ocean. The land carbon model can optionally include both nitrogen and phosphorous limitation on the land carbon uptake. The ocean carbon model simulates the evolution of nitrate, oxygen, dissolved inorganic carbon, alkalinity and iron with one class of phytoplankton and zooplankton. From two multi-centennial simulations of the pre-industrial period with different land carbon model configurations, we evaluate the equilibration of the carbon cycle and present the spatial and temporal variability in key carbon exchanges. For the land carbon cycle, leaf area index is simulated reasonably, and seasonal carbon exchange is well represented. Interannual variations of land carbon exchange are relatively large, driven by variability in precipitation and temperature. We find that the response of the ocean carbon cycle shows reasonable agreement with observations and very good agreement with existing Coupled Model Intercomparison Project (CMIP5) models. While our model over estimates surface nitrate values, the primary productivity agrees well with observations. Our analysis highlights some deficiencies inherent in the carbon models and where the carbon simulation is negatively impacted by known biases in the underlying physical model. We conclude the study with a brief discussion of key developments required to further improve the realism of our model simulation.

  11. The carbon cycle in the Australian Community Climate and Earth System Simulator (ACCESS-ESM1 – Part 1: Model description and pre-industrial simulation

    Directory of Open Access Journals (Sweden)

    R. M. Law

    2015-09-01

    Full Text Available Earth System Models (ESMs that incorporate carbon-climate feedbacks represent the present state of the art in climate modelling. Here, we describe the Australian Community Climate and Earth System Simulator (ACCESS-ESM1 that combines existing ocean and land carbon models into the physical climate model to simulate exchanges of carbon between the land, atmosphere and ocean. The land carbon model can optionally include both nitrogen and phosphorous limitation on the land carbon uptake. The ocean carbon model simulates the evolution of nitrate, oxygen, dissolved inorganic carbon, alkalinity and iron with one class of phytoplankton and zooplankton. From two multi-centennial simulations of the pre-industrial period with different land carbon model configurations, we evaluate the equilibration of the carbon cycle and present the spatial and temporal variability in key carbon exchanges. For the land carbon cycle, leaf area index is simulated reasonably, and seasonal carbon exchange is well represented. Interannual variations of land carbon exchange are relatively large, driven by variability in precipitation and temperature. We find that the response of the ocean carbon cycle shows reasonable agreement with observations and very good agreement with existing Coupled Model Intercomparison Project (CMIP5 models. While our model over estimates surface nitrate values, the primary productivity agrees well with observations. Our analysis highlights some deficiencies inherent in the carbon models and where the carbon simulation is negatively impacted by known biases in the underlying physical model. We conclude the study with a brief discussion of key developments required to further improve the realism of our model simulation.

  12. AN AGCM +SSiB MODEL SIMULATION ON CHANGES IN PALAEOMONSOON CLIMATE AT 21 KA BP IN CHINA

    Institute of Scientific and Technical Information of China (English)

    陈星; 于革; 刘健

    2001-01-01

    The numerical simulation experiment of climate at Last Glacial Maximum (LGM, 21 ka BP)in China is made by using an atmospheric general circulation model (AGCM) coupled with land surface processes (AGCM+SSiB) and earth orbital parameters and boundary forcing conditions at 21 ka. The modeled climate features are compared with reconstructed conditions at 21 ka from palco-lake data and pollen data. The results show that the simulated climate conditions at 21 ka in China are fairly comparable with palco-climatological data. The climate features at 21 ka in China from the experiment are characterized by a drier in the east and a wetter in the west and in the Tibetan Plateau as well. According to the analysis of distribution of pressure and precipitation, as well as the intensity of atmospheric circulation at 21 ka, monsoon circulation in eastern Asia was significantly weak comparing with the present. In the Tibetan Plateau, the intensity of summer monsoon circulation was strengthened, and winter monsoon was a little stronger than the present.The simulation with given forcing boundary conditions, especially the different vegetation coverage, can reproduce the climate condition at the LGM in China, and therefore provides dynamical mechanisms on the climate changes at 21 ka.

  13. The simulation of medicanes in a high-resolution regional climate model

    Energy Technology Data Exchange (ETDEWEB)

    Cavicchia, Leone [Centro Euro-Mediterraneo per i Cambiamenti Climatici, Bologna (Italy); Helmholtz-Zentrum Geesthacht, Institute of Coastal Research, Geesthacht (Germany); Ca' Foscari University, Venice (Italy); Storch, Hans von [Helmholtz-Zentrum Geesthacht, Institute of Coastal Research, Geesthacht (Germany); University of Hamburg, Meteorological Institute, Hamburg (Germany)

    2012-11-15

    Medicanes, strong mesoscale cyclones with tropical-like features, develop occasionally over the Mediterranean Sea. Due to the scarcity of observations over sea and the coarse resolution of the long-term reanalysis datasets, it is difficult to study systematically the multidecadal statistics of sub-synoptic medicanes. Our goal is to assess the long-term variability and trends of medicanes, obtaining a long-term climatology through dynamical downscaling of the NCEP/NCAR reanalysis data. In this paper, we examine the robustness of this method and investigate the value added for the study of medicanes. To do so, we performed several climate mode simulations with a high resolution regional atmospheric model (CCLM) for a number of test cases described in the literature. We find that the medicanes are formed in the simulations, with deeper pressures and stronger winds than in the driving global NCEP reanalysis. The tracks are adequately reproduced. We conclude that our methodology is suitable for constructing multi-decadal statistics and scenarios of current and possible future medicane activities. (orig.)

  14. Regional moisture change over India during the past Millennium: A comparison of multi-proxy reconstructions and climate model simulations

    Science.gov (United States)

    Polanski, Stefan; Fallah, Bijan; Befort, Daniel J.; Prasad, Sushma; Cubasch, Ulrich

    2014-11-01

    The Indian Monsoon Variability during the past Millennium has been simulated with the ECHAM5 model in two different time slices: Medieval Climate Anomaly and the Little Ice Age. The simulations are compared with new centennial-resolving paleo-reconstructions inferred from various well-dated multi-proxies from two core regions, the Himalaya and Central India. A qualitative moisture index is derived from the proxies and compared with simulated moisture anomalies. The reconstructed paleo-hydrological changes between the Little Ice Age and the Medieval Climate Anomaly depict a dipole pattern between Himalaya and Central India, which is also captured by the model. In the Medieval Climate Anomaly the model exhibits stronger (weaker) dipole signals during summer (winter) compared to Little Ice Age. In summer (winter) months of "Medieval Climate Anomaly minus Little Ice Age" the model simulates wetter conditions over eastern (western and central) Himalaya. Over Central India, a simulated weakening of Indian Summer Monsoon during warmer climate is coincident with reconstructed drying signal in the Lonar Lake record. Based on the model simulations, we can differentiate three physical mechanisms which can lead to the moisture anomalies: (i) the western and central Himalaya are influenced by extra-tropical Westerlies during winter, (ii) the eastern Himalaya is affected by summer variations of temperature gradient between Bay of Bengal and Indian subcontinent and by a zonal band of intensified Indian-East Asian monsoon link north of 25°N, and (iii) Central India is dominated by summer sea surface temperature anomalies in the northern Arabian Sea which have an effect on the large-scale advection of moist air masses. The temperatures in the Arabian Sea are linked to the Indo Pacific Warm Pool, which modulates the Indian monsoon strength.

  15. The Interactive Climate and Vegetation Along the Pole-Equator Belts Simulated by a Global Coupled Model

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The interaction between climate and vegetation along four Pole-Equator-Pole (PEP) belts were explored using a global two-way coupled model, AVIM-GOALS, which links the ecophysiological processes at the land surface with the general circulation model (GCM). The PEP belts are important in linking the climate change with the variation of sea and land, including terrestrial ecosystems. Previous PEP belts studies have mainly focused on the paleoclimate variation and its reconstruction. This study analyzes and discusses the interaction between modern climate and vegetation represented by leaf area index (LAI) and net primary production (NPP). The results show that the simulated LAI variation, corresponding to the observed LAI variation, agrees with the peak-valley variation of precipitation in these belts. The annual mean NPP simulated by the coupled model is also consistent with PIK NPP data in its overall variation trend along the four belts, which is a good example to promote global ecological studies by coupling the climate and vegetation models. A large discrepancy between the simulated and estimated LAI emerges to the south of 15°N along PEP 3 and to the south of 18°S in PEP 1S, and the discrepancy for the simulated NPP and PIK data in the two regions is relatively smaller in contrast to the LAI difference. Precipitation is a key factor affecting vegetation variation, and the overall trend of LAI and NPP corresponds more obviously to precipitation variation than temperature change along most parts of these PEP belts.

  16. Evidence for signiifcant climate impacts in monsoonal Asia at 8.2 ka from multiple proxies and model simulations

    Institute of Scientific and Technical Information of China (English)

    MORRILL Carrie; WAGNER Amy J; OTTO-BLIESNER Bette L; ROSENBLOOM Nan

    2011-01-01

    Given the likelihood of future reductions in the strength of the Atlantic Meridional Overturning Circulation (AMOC), it is important to document how changes in the AMOC have altered climate patterns in the past and to assess the skill of coupled climate models in reproducing these teleconnections. Of past abrupt changes in the AMOC, the 8.2 ka event provides a particularly useful case study because its duration, magnitude of AMOC reduction and background climate state are closest to conditions expected in the future. In this research, we present an expanded proxy synthesis of the 8.2 ka event in monsoonal Asia, including new high-resolution lake and bog records, more sites from the East Asia monsoon region and proxies of winter monsoon strength. We compare proxy evidence with a new simulation of the 8.2 ka event using the Community Climate System Model version 3 (CCSM3) and prescribing North Atlantic freshwater forcing according to the latest reconstructions. We ifnd clear and objectively-determined evidence for 8.2 ka climate anomalies at nearly all of the fourteen proxy sites, emphasizing the strong and widespread impacts of the event in monsoonal Asia during both summer and winter seasons. The model simulation corroborates that these anomalies, described generally as a weakening of the summer monsoon and strengthening of the winter monsoon, were likely caused by a reduction of the AMOC. Examination of regional anomalies in East Asia reveals some spatial heterogeneity, however, that in the model simulation is caused by contraction of the seasonal migration of the subtropical monsoon front. The duration of climate anomalies at 8.2 ka in monsoonal Asia, both in proxy records and the model simulation, generally matches the duration of the event in Greenland ice core δ18O, further supporting a tight connection to the North Atlantic.

  17. Global Climate Model Simulated Hydrologic Droughts and Floods in the Nelson-Churchill Watershed

    Science.gov (United States)

    Vieira, M. J. F.; Stadnyk, T. A.; Koenig, K. A.

    2014-12-01

    There is uncertainty surrounding the duration, magnitude and frequency of historical hydroclimatic extremes such as hydrologic droughts and floods prior to the observed record. In regions where paleoclimatic studies are less reliable, Global Climate Models (GCMs) can provide useful information about past hydroclimatic conditions. This study evaluates the use of Coupled Model Intercomparison Project 5 (CMIP5) GCMs to enhance the understanding of historical droughts and floods across the Canadian Prairie region in the Nelson-Churchill Watershed (NCW). The NCW is approximately 1.4 million km2 in size and drains into Hudson Bay in Northern Manitoba, Canada. One hundred years of observed hydrologic records show extended dry and wet periods in this region; however paleoclimatic studies suggest that longer, more severe droughts have occurred in the past. In Manitoba, where hydropower is the primary source of electricity, droughts are of particular interest as they are important for future resource planning. Twenty-three GCMs with daily runoff are evaluated using 16 metrics for skill in reproducing historic annual runoff patterns. A common 56-year historic period of 1950-2005 is used for this evaluation to capture wet and dry periods. GCM runoff is then routed at a grid resolution of 0.25° using the WATFLOOD hydrological model storage-routing algorithm to develop streamflow scenarios. Reservoir operation is naturalized and a consistent temperature scenario is used to determine ice-on and ice-off conditions. These streamflow simulations are compared with the historic record to remove bias using quantile mapping of empirical distribution functions. GCM runoff data from pre-industrial and future projection experiments are also bias corrected to obtain extended streamflow simulations. GCM streamflow simulations of more than 650 years include a stationary (pre-industrial) period and future periods forced by radiative forcing scenarios. Quantile mapping adjusts for magnitude

  18. Vegetation-climate feedback causes reduced precipitation in CMIP5 regional Earth system model simulation over Africa

    Science.gov (United States)

    Wu, Minchao; Smith, Benjamin; Schurgers, Guy; Lindström, Joe; Rummukainen, Markku; Samuelsson, Patrick

    2013-04-01

    Terrestrial ecosystems have been demonstrated to play a significant role within the climate system, amplifying or dampening climate change via biogeophysical and biogeochemical exchange with the atmosphere and vice versa (Cox et al. 2000; Betts et al. 2004). Africa is particularly vulnerable to climate change and studies of vegetation-climate feedback mechanisms on Africa are still limited. Our study is the first application of A coupled Earth system model at regional scale and resolution over Africa. We applied a coupled regional climate-vegetation model, RCA-GUESS (Smith et al. 2011), over the CORDEX Africa domain, forced by boundary conditions from a CanESM2 CMIP5 simulation under the RCP8.5 future climate scenario. The simulations were from 1961 to 2100 and covered the African continent at a horizontal grid spacing of 0.44°. RCA-GUESS simulates changes in the phenology, productivity, relative cover and population structure of up to eight plant function types (PFTs) in response to forcing from the climate part of the model. These vegetation changes feedback to simulated climate through dynamic adjustments in surface energy fluxes and surface properties. Changes in the net ecosystem-atmosphere carbon flux and its components net primary production (NPP), heterotrophic respiration and emissions from biomass burning were also simulated but do not feedback to climate in our model. Constant land cover was assumed. We compared simulations with and without vegetation feedback switched "on" to assess the influence of vegetation-climate feedback on simulated climate, vegetation and ecosystem carbon cycling. Both positive and negative warming feedbacks were identified in different parts of Africa. In the Sahel savannah zone near 15°N, reduced vegetation cover and productivity, and mortality caused by a deterioration of soil water conditions led to a positive warming feedback mediated by decreased evapotranspiration and increased sensible heat flux between vegetation and

  19. Evaluation of Present-day Aerosols over China Simulated from the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP)

    Science.gov (United States)

    Liao, H.; Chang, W.

    2014-12-01

    High concentrations of aerosols over China lead to strong radiative forcing that is important for both regional and global climate. To understand the representation of aerosols in China in current global climate models, we evaluate extensively the simulated present-day aerosol concentrations and aerosol optical depth (AOD) over China from the 12 models that participated in Atmospheric Chemistry & Climate Model Intercomparison Project (ACCMIP), by using ground-based measurements and satellite remote sensing. Ground-based measurements of aerosol concentrations used in this work include those from the China Meteorological Administration (CMA) Atmosphere Watch Network (CAWNET) and the observed fine-mode aerosol concentrations collected from the literature. The ground-based measurements of AOD in China are taken from the AErosol RObotic NETwork (AERONET), the sites with CIMEL sun photometer operated by Institute of Atmospheric Physics, Chinese Academy of Sciences, and from Chinese Sun Hazemeter Network (CSHNET). We find that the ACCMIP models generally underestimate concentrations of all major aerosol species in China. On an annual mean basis, the multi-model mean concentrations of sulfate, nitrate, ammonium, black carbon, and organic carbon are underestimated by 63%, 73%, 54%, 53%, and 59%, respectively. The multi-model mean AOD values show low biases of 20-40% at studied sites in China. The ACCMIP models can reproduce seasonal variation of nitrate but cannot capture well the seasonal variations of other aerosol species. Our analyses indicate that current global models generally underestimate the role of aerosols in China in climate simulations.

  20. Reproducibility of summertime diurnal precipitation over northern Eurasia simulated by CMIP5 climate models

    Science.gov (United States)

    Hirota, N.; Takayabu, Y. N.

    2015-12-01

    Reproducibility of diurnal precipitation over northern Eurasia simulated by CMIP5 climate models in their historical runs were evaluated, in comparison with station data (NCDC-9813) and satellite data (GSMaP-V5). We first calculated diurnal cycles by averaging precipitation at each local solar time (LST) in June-July-August during 1981-2000 over the continent of northern Eurasia (0-180E, 45-90N). Then we examined occurrence time of maximum precipitation and a contribution of diurnally varying precipitation to the total precipitation.The contribution of diurnal precipitation was about 21% in both NCDC-9813 and GSMaP-V5. The maximum precipitation occurred at 18LST in NCDC-9813 but 16LST in GSMaP-V5, indicating some uncertainties even in the observational datasets. The diurnal contribution of the CMIP5 models varied largely from 11% to 62%, and their timing of the precipitation maximum ranged from 11LST to 20LST. Interestingly, the contribution and the timing had strong negative correlation of -0.65. The models with larger diurnal precipitation showed precipitation maximum earlier around noon. Next, we compared sensitivity of precipitation to surface temperature and tropospheric humidity between 5 models with large diurnal precipitation (LDMs) and 5 models with small diurnal precipitation (SDMs). Precipitation in LDMs showed high sensitivity to surface temperature, indicating its close relationship with local instability. On the other hand, synoptic disturbances were more active in SDMs with a dominant role of the large scale condensation, and precipitation in SDMs was more related with tropospheric moisture. Therefore, the relative importance of the local instability and the synoptic disturbances was suggested to be an important factor in determining the contribution and timing of the diurnal precipitation. Acknowledgment: This study is supported by Green Network of Excellence (GRENE) Program by the Ministry of Education, Culture, Sports, Science and Technology

  1. Waves and eddies simulated by high-resolution Global Climate Modeling of Saturn's troposphere and stratosphere

    Science.gov (United States)

    Spiga, Aymeric; Guerlet, Sandrine; Meurdesoif, Yann; Indurain, Mikel; Millour, Ehouarn; Dubos, Thomas; Sylvestre, Mélody; Leconte, Jérémy; Fouchet, Thierry

    2015-11-01

    The longevity of the Cassini mission permitted a detailed analysis of Saturn's tropospheric storms, an exceptional coverage of Saturn's Great White Spot (and subsequent stratospheric warming), an assessment of the remarkable stability of the hexagonal polar jet, and the seasonal monitoring of Saturn's equatorial oscillation. Those observations open new questions that add to those related to the extent and forcing of Saturn's alternated jets. One of the best step forward to progress is to build a Global Climate Model (GCM) for giant planets by coupling an hydrodynamical solver (dynamical core) with physical models for external forcings on the fluid. We built a new GCM for Saturn both versatile and powerful enough to resolve resolve the eddies arising from hydrodynamical instabilities and forcing the planetary-scale jets, extend from the troposphere to the stratosphere with good enough vertical resolution, and use optimized radiative transfer to predict seasonal tendencies over decade-long giant planets' years. To that end, we coupled our seasonal radiative model tailored for Saturn with DYNAMICO, the next state-of-the-art dynamical core for Earth and planetary climate studies in our lab, using an original icosahedral mapping of the planetary sphere which ensures excellent conservation and scalability properties in massively parallel resources. Using a new petaflops acquisition by CINES (France), we run our GCM for Saturn down to unprecedented resolutions of 1/4° and 1/8°, and to run sensitivity tests at 1/2° resolution. Those high-resolution GCM runs show a detailed view into a striking variety of eddies and vortices on Saturn, as well as the arising of alternated banded jets, the formation of a polar vortex, the deformation of the polar jet into polygonal structures. We will assess the nature and characteristics of both eddies and eddy-driven features in the troposphere and in the stratosphere, using spectral and dynamical analysis. We will discuss how close our

  2. An evaluation of high-resolution regional climate model simulations of snow cover and albedo over the Rocky Mountains, with implications for the simulated snow-albedo feedback

    Science.gov (United States)

    Minder, Justin R.; Letcher, Theodore W.; Skiles, S. McKenzie

    2016-08-01

    The snow-albedo feedback (SAF) strongly influences climate over midlatitude mountainous regions. However, over these regions the skill of regional climate models (RCMs) at simulating properties such as snow cover and surface albedo is poorly characterized. These properties are evaluated in a pair of 7 year long high-resolution RCM simulations with the Weather Research and Forecasting model over the central Rocky Mountains. Key differences between the simulations include the computational domain (regional versus continental) and land surface model used (Noah versus Noah-MP). Simulations are evaluated against high-resolution satellite estimates of snow cover and albedo from the Moderate Resolution Imaging Spectroradiometer. Both simulations generally reproduce the observed seasonal and spatial variability of snow cover and also exhibit important biases. One simulation substantially overpredicts subpixel fractional snow cover over snowy pixels (by up to 0.4) causing large positive biases in surface albedo, likely due in part to inadequate representation of canopy effects. The other simulation exhibits a negative bias in areal snow extent (as much as 19% of the analysis domain). Surface measurements reveal large positive biases in snow albedo (exceeding 0.2) during late spring caused by neglecting radiative effects of impurities deposited onto snow. Semi-idealized climate change experiments show substantially different magnitudes of SAF-enhanced warming in the two simulations that can be tied to the differences in snow cover in their control climates. More confident projections of regional climate change over mountains will require further work to evaluate and improve representation of snow cover and albedo in RCMs.

  3. Simulation Modeling of Lakes in Undergraduate and Graduate Classrooms Increases Comprehension of Climate Change Concepts and Experience with Computational Tools

    Science.gov (United States)

    Carey, Cayelan C.; Gougis, Rebekka Darner

    2016-08-01

    Ecosystem modeling is a critically important tool for environmental scientists, yet is rarely taught in undergraduate and graduate classrooms. To address this gap, we developed a teaching module that exposes students to a suite of modeling skills and tools (including computer programming, numerical simulation modeling, and distributed computing) that students apply to study how lakes around the globe are experiencing the effects of climate change. In the module, students develop hypotheses about the effects of different climate scenarios on lakes and then test their hypotheses using hundreds of model simulations. We taught the module in a 4-hour workshop and found that participation in the module significantly increased both undergraduate and graduate students' understanding about climate change effects on lakes. Moreover, participation in the module also significantly increased students' perceived experience level in using different software, technologies, and modeling tools. By embedding modeling in an environmental science context, non-computer science students were able to successfully use and master technologies that they had previously never been exposed to. Overall, our findings suggest that modeling is a powerful tool for catalyzing student learning on the effects of climate change.

  4. Simulation Modeling of Lakes in Undergraduate and Graduate Classrooms Increases Comprehension of Climate Change Concepts and Experience with Computational Tools

    Science.gov (United States)

    Carey, Cayelan C.; Gougis, Rebekka Darner

    2017-02-01

    Ecosystem modeling is a critically important tool for environmental scientists, yet is rarely taught in undergraduate and graduate classrooms. To address this gap, we developed a teaching module that exposes students to a suite of modeling skills and tools (including computer programming, numerical simulation modeling, and distributed computing) that students apply to study how lakes around the globe are experiencing the effects of climate change. In the module, students develop hypotheses about the effects of different climate scenarios on lakes and then test their hypotheses using hundreds of model simulations. We taught the module in a 4-hour workshop and found that participation in the module significantly increased both undergraduate and graduate students' understanding about climate change effects on lakes. Moreover, participation in the module also significantly increased students' perceived experience level in using different software, technologies, and modeling tools. By embedding modeling in an environmental science context, non-computer science students were able to successfully use and master technologies that they had previously never been exposed to. Overall, our findings suggest that modeling is a powerful tool for catalyzing student learning on the effects of climate change.

  5. Combining state-and-transition simulations and species distribution models to anticipate the effects of climate change

    Directory of Open Access Journals (Sweden)

    Brian W. Miller

    2015-05-01

    Full Text Available State-and-transition simulation models (STSMs are known for their ability to explore the combined effects of multiple disturbances, ecological dynamics, and management actions on vegetation. However, integrating the additional impacts of climate change into STSMs remains a challenge. We address this challenge by combining an STSM with species distribution modeling (SDM. SDMs estimate the probability of occurrence of a given species based on observed presence and absence locations as well as environmental and climatic covariates. Thus, in order to account for changes in habitat suitability due to climate change, we used SDM to generate continuous surfaces of species occurrence probabilities. These data were imported into ST-Sim, an STSM platform, where they dictated the probability of each cell transitioning between alternate potential vegetation types at each time step. The STSM was parameterized to capture additional processes of vegetation growth and disturbance that are relevant to a keystone species in the Greater Yellowstone Ecosystem—whitebark pine (Pinus albicaulis. We compared historical model runs against historical observations of whitebark pine and a key disturbance agent (mountain pine beetle, Dendroctonus ponderosae, and then projected the simulation into the future. Using this combination of correlative and stochastic simulation models, we were able to reproduce historical observations and identify key data gaps. Results indicated that SDMs and STSMs are complementary tools, and combining them is an effective way to account for the anticipated impacts of climate change, biotic interactions, and disturbances, while also allowing for the exploration of management options.

  6. Simulating Global Climate Summits

    Science.gov (United States)

    Vesperman, Dean P.; Haste, Turtle; Alrivy, Stéphane

    2014-01-01

    One of the most persistent and controversial issues facing the global community is climate change. With the creation of the UN Framework Convention on Climate Change (UNFCCC) in 1992 and the Kyoto Protocol (1997), the global community established some common ground on how to address this issue. However, the last several climate summits have failed…

  7. Future changes in extreme precipitation in the Rhine basin based on global and regional climate model simulations

    Directory of Open Access Journals (Sweden)

    S. C. van Pelt

    2012-05-01

    Full Text Available Probability estimates of the future change of extreme precipitation events are usually based on a limited number of available Global Climate Model (GCM or Regional Climate Model (RCM simulations. Since floods are related to heavy precipitation events, this restricts the assessment of flood risks. In this study a relatively simple method has been developed to get a better picture of the range of changes in extreme precipitation events. Five bias corrected RCM simulations of the 1971–2100 climate for a single greenhouse gas emission scenario (A1B SRES were available for the Rhine basin. To increase the size of this five-member RCM ensemble, 13 additional GCM simulations were analysed. The climate responses of the GCMs are used to modify an observed (1961–1995 precipitation/temperature time series with an advanced delta change approach. Changes in the temporal means and variability are taken into account. Time series resampling was applied to extend 35-yr GCM and RCM time-slices to 3000-yr series to estimate extreme precipitation with return periods up to 1000 yr. It is found that the range of future change of extreme precipitation across the five-member RCM ensemble is similar to results from the 13-member GCM ensemble. For the RCM ensemble, the time series modification procedure also resulted in a similar climate response compared to the signal deduced from the direct model simulations. The changes from the individual RCM simulations, however, systematically differ from those of the driving GCMs, especially for long return periods.

  8. TRACKING CLIMATE MODELS

    Data.gov (United States)

    National Aeronautics and Space Administration — CLAIRE MONTELEONI*, GAVIN SCHMIDT, AND SHAILESH SAROHA* Climate models are complex mathematical models designed by meteorologists, geophysicists, and climate...

  9. Downscaling a global climate model to simulate climate change over the US and the implication on regional and urban air quality

    Directory of Open Access Journals (Sweden)

    M. Trail

    2013-09-01

    Full Text Available Climate change can exacerbate future regional air pollution events by making conditions more favorable to form high levels of ozone. In this study, we use spectral nudging with the Weather Research and Forecasting (WRF model to downscale NASA earth system GISS modelE2 results during the years 2006 to 2010 and 2048 to 2052 over the contiguous United States in order to compare the resulting meteorological fields from the air quality perspective during the four seasons of five-year historic and future climatological periods. GISS results are used as initial and boundary conditions by the WRF regional climate model (RCM to produce hourly meteorological fields. The downscaling technique and choice of physics parameterizations used are evaluated by comparing them with in situ observations. This study investigates changes of similar regional climate conditions down to a 12 km by 12 km resolution, as well as the effect of evolving climate conditions on the air quality at major US cities. The high-resolution simulations produce somewhat different results than the coarse-resolution simulations in some regions. Also, through the analysis of the meteorological variables that most strongly influence air quality, we find consistent changes in regional climate that would enhance ozone levels in four regions of the US during fall (western US, Texas, northeastern, and southeastern US, one region during summer (Texas, and one region where changes potentially would lead to better air quality during spring (Northeast. Changes in regional climate that would enhance ozone levels are increased temperatures and stagnation along with decreased precipitation and ventilation. We also find that daily peak temperatures tend to increase in most major cities in the US, which would increase the risk of health problems associated with heat stress. Future work will address a more comprehensive assessment of emissions and chemistry involved in the formation and removal of air

  10. An evaluation of the simulations of the Arctic Intermediate Water in climate models and reanalyses

    Institute of Scientific and Technical Information of China (English)

    LI Xiang; SU Jie; ZHAO Jinping

    2014-01-01

    The simulations of the Arctic Intermediate Water in four datasets of climate models and reanalyses, CCSM3, CCSM4, SODA and GLORYS, are analyzed and evaluated. The climatological core temperatures and depths in both CCSM models exhibit deviations over 0.5°C and 200 m from the PHC. SODA reanalysis reproduces relatively reasonable spatial patterns of core temperature and depth, while GLORYS, another reanalysis, shows a remarkable cooling and deepening drift compared with the result at the beginning of the dataset especially in the Eurasian Basin (about 2°C). The heat contents at the depth of intermediate water in the CCSM models are overestimated with large positive errors nearly twice of that in the PHC. To the contrary, the GLORYS in 2009 show a negative error with a similar magnitude, which means the characteristic of the water mass is totally lost. The circulations in the two reanalyses at the depth of intermediate water are more energetic and realistic than those in the CCSMs, which is attributed to the horizontal eddy-permitting reso-lution. The velocity fields and the transports in the Fram Strait are also investigated. The necessity of finer horizontal resolution is concluded again. The northward volume transports are much larger in the two re-analyses, although they are still weak comparing with mooring observations. Finally, an investigation of the impact of assimilation is done with an evidence of the heat input from assimilation. It is thought to be a reason for the good performance in the SODA, while the GLORYS drifts dramatically without assimilation data in the Arctic Ocean.

  11. Enhanced Vertical Atmosphere Resolution improves Climate Model Simulation of Tropical Atlantic Sea Surface Temperature and Interannual Variability

    Science.gov (United States)

    Harlass, Jan; Latif, Mojib; Park, Wonsun

    2015-04-01

    A long-standing problem in climate modelling is the inaccurate simulation of tropical Atlantic (TA) sea surface temperature (SST), known as the TA SST bias. Basically all state-of-the-art global climate models suffer from a reversed equatorial zonal SST gradient in the Atlantic and too warm surface temperatures in the Benguela upwelling region. These biases have far-reaching consequences for climate prediction as they go along, among others, with erroneous precipitation patterns. We used the coupled atmosphere-ocean-sea ice Kiel Climate Model (KCM) to conduct experiments with varying atmosphere model resolutions, while keeping the ocean component unchanged. Atmosphere model resolution has been increased not only in the horizontal (from T42 to T159), but also in the vertical (from L31 to L62). We show that the TA SST bias can be largely reduced by increasing both the atmospheric horizontal and vertical resolution. In particular, the zonal SST gradient along the equator is simulated with the correct sign. At high horizontal resolution, enhanced vertical resolution is indispensable to substantially improve the simulation of TA SST by enhancing the surface wind stress. This also reduces biases in the upper ocean thermal structure and precipitation. A major step forward is a more northward position of the Intertropical Convergence Zone. Although enhanced horizontal resolution alone leads to some improvement in the mean climate, typical bias patterns, characterized by a reversed zonal SST gradient at the equator and too warm SST along the Benguela Coast, remain. Notable changes in the pattern of interannual SST variability occur with increased resolution. Seasonal phase locking is captured only at high vertical resolution, although a phase lag of 2 months still exists. Our study highlights the importance of sufficiently high atmospheric model resolution and, equally important, a consistent choice of horizontal and vertical model resolution.

  12. Simulation of the intraseasonal variability over the Eastern Pacific ITCZ in climate models

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Xianan [Univ. of California, Los Angeles, CA (United States); Waliser, Duane E. [California Inst. of Technology (CalTech), La Canada Flintridge, CA (United States). Jet Propulsion Lab.; Kim, Daehyun [Columbia Univ., New York, NY (United States); Zhao, Ming [Princeton Univ., NJ (United States); Sperber, Kenneth R. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Stern, William F. [Princeton Univ., NJ (United States); Schubert, Siegfried D. [NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States); Zhang, Guang J. [Scripps Institute of Oceanography. La Jolla, California (United States); Wang, Wanqiu [National Oceanic and Atmospheric Administration (NOAA), National Centers for Environmental Protection. Camp Springs, MD (United States); Khairoutdinov, Marat [Institute for Terrestrial and Planetary Atmospheres. Stony Brook Univ., NY (United States); Neale, Richard B. [National Center for Atmospheric Research. Boulder, CO (United States); Lee, Myong-In [Ulsan National Institute for Science and Technology. Seoul (Korea)

    2012-08-01

    During boreal summer, convective activity over the eastern Pacific (EPAC) inter-tropical convergence zone (ITCZ) exhibits vigorous intraseasonal variability (ISV). Previous observational studies identified two dominant ISV modes over the EPAC, i.e., a 40-day mode and a quasi-biweekly mode (QBM). The 40-day ISV mode is generally considered a local expression of the Madden-Julian Oscillation. However, in addition to the eastward propagation, northward propagation of the 40-day mode is also evident. The QBM mode bears a smaller spatial scale than the 40-day mode, and is largely characterized by northward propagation. While the ISV over the EPAC exerts significant influences on regional climate/weather systems, investigation of contemporary model capabilities in representing these ISV modes over the EPAC is limited. In this study, the model fidelity in representing these two dominant ISV modes over the EPAC is assessed by analyzing six atmospheric and three coupled general circulation models (GCMs), including one super-parameterized GCM (SPCAM) and one recently developed high-resolution GCM (GFDL HIRAM) with horizontal resolution of about 50 km. While it remains challenging for GCMs to faithfully represent these two ISV modes including their amplitude, evolution patterns, and periodicities, encouraging simulations are also noted. In general, SPCAM and HIRAM exhibit relatively superior skill in representing the two ISV modes over the EPAC. While the advantage of SPCAM is achieved through explicit representation of the cumulus process by the embedded 2-D cloud resolving models, the improved representation in HIRAM could be ascribed to the employment of a strongly entraining plume cumulus scheme, which inhibits the deep convection, and thus effectively enhances the stratiform rainfall. The sensitivity tests based on HIRAM also suggest that fine horizontal resolution could also be conducive to realistically capture the ISV over the EPAC, particularly for the QBM mode

  13. Simulating Pacific Northwest Forest Response to Climate Change: How We Made Model Results Useful for Vulnerability Assessments

    Science.gov (United States)

    Kim, J. B.; Kerns, B. K.; Halofsky, J.

    2014-12-01

    GCM-based climate projections and downscaled climate data proliferate, and there are many climate-aware vegetation models in use by researchers. Yet application of fine-scale DGVM based simulation output in national forest vulnerability assessments is not common, because there are technical, administrative and social barriers for their use by managers and policy makers. As part of a science-management climate change adaptation partnership, we performed simulations of vegetation response to climate change for four national forests in the Blue Mountains of Oregon using the MC2 dynamic global vegetation model (DGVM) for use in vulnerability assessments. Our simulation results under business-as-usual scenarios suggest a starkly different future forest conditions for three out of the four national forests in the study area, making their adoption by forest managers a potential challenge. However, using DGVM output to structure discussion of potential vegetation changes provides a suitable framework to discuss the dynamic nature of vegetation change compared to using more commonly available model output (e.g. species distribution models). From the onset, we planned and coordinated our work with national forest managers to maximize the utility and the consideration of the simulation results in planning. Key lessons from this collaboration were: (1) structured and strategic selection of a small number climate change scenarios that capture the range of variability in future conditions simplified results; (2) collecting and integrating data from managers for use in simulations increased support and interest in applying output; (3) a structured, regionally focused, and hierarchical calibration of the DGVM produced well-validated results; (4) simple approaches to quantifying uncertainty in simulation results facilitated communication; and (5) interpretation of model results in a holistic context in relation to multiple lines of evidence produced balanced guidance. This latest

  14. Performance of CMIP5 Models in the Simulation of Climate Characteristics of Synoptic Patterns over East Asia

    Institute of Scientific and Technical Information of China (English)

    2015-01-01

    The evolution of daily synoptic weather patterns is the main driver of day-to-day weather change. These patterns are generally associated with changes in temperature, precipitation, etc., especially during extreme weathers. Evaluating the ability of climate models to reproduce the frequency and intensity of daily synoptic patterns is essential for increasing confi dence in future pro jections. In this study, we investigated the ability of 34 global climate models (GCMs) included in the Coupled Model Intercomparison Project Phase 5 (CMIP5) to simulate synoptic patterns over East Asia and their evolution features in winter and summer. Daily synoptic patterns in sea level pressure and their occurrence frequencies were identifi ed by using an objective clustering algorithm, self-organizing maps (SOMs). The evaluation consists of correlating the frequencies of these patterns in the 34 CMIP5 models with the frequencies in the NCEP reanalysis during the baseline period of 1980–1999. The results illustrated that most of these models were able to reproduce the synoptic patterns of the NCEP reanalysis. In addition, the frequencies of temporal sea level pressure (SLP) anomaly patterns were reproduced by most of the models over the baseline period, but the frequencies of spatial SLP anomaly patterns were only reproduced by a few GCMs. Overall, the models performed better in summer than in winter. Comprehensive evaluation shows that the four top-performing models for both winter and summer are bcc-csm1-1-m, NorESM1-M, MRI-CGCM3, and CCSM4. They show good performance in simulating the daily synoptic patterns in SLP and in reproducing their occurrence frequencies. The results showed that the SOM was an eff ective tool for diff erentiating characteristics of synoptic circulation patterns and for evaluating the ability of climate models to simulate the frequency of daily synoptic patterns. The results can also help users to choose a better model for future climate projection and

  15. Climate Model Simulation of Present and Future Extreme Events in Latin America and the Caribbean: What Spatial Resolution is Required?

    Science.gov (United States)

    Rowe, C. M.; Oglesby, R. J.; Mawalagedara, R.; Mohammad Abadi Kamarei, A.

    2015-12-01

    Latin America and the Caribbean are at risk of extreme climate events, including flooding rains, damaging winds, drought, heat waves, and in high elevation mountainous regions, excessive snowfalls. The causes of these events are numerous - flooding rains and damaging winds are often associated with tropical cyclones, but also can occur, either separately or in tandem, due to smaller, more localized storms. Similarly, heat waves and droughts can be large scale or localized, and frequently occur together (as excessive drying can lead to enhanced heating, while enhanced heating in turn promotes additional drying). Even in the tropics, extreme snow and ice events can have severe consequences due to avalanches, and also impact water resources. Understanding and modeling the climate controls behind these extreme events requires consideration of a range of time and space scales. A common strategy is to use a global climate model (GCM) to simulate the large-scale (~100km) daily atmospheric controls on extreme events. A limited area, high resolution regional climate model (RCM) is then employed to dynamically downscale the results, so as to better incorporate the influence of topography and, secondarily, the nature of the land cover. But what resolution is required to provide the necessary results, i.e., minimize biases due to improper resolution? In conjunction with our partners from participating Latin American and Caribbean nations, we have made an extensive series of simulations, both region-wide and for individual countries, using the WRF regional climate model to downscale output from a variety of GCMs, as well as Reanalyses (as a proxy for observations). The simulations driven by the Reanalyses are used for robust model verification against actual weather station observations. The simulations driven by GCMs are designed to provide projections of future climate, including importantly how the nature and number of extreme events may change through coming decades. Our

  16. Using the WRF Regional Model to Produce High Resolution AR4 Simulations of Climate Change for Mesoamerica

    Science.gov (United States)

    Oglesby, R. J.; Rowe, C. M.; Hays, C.

    2010-12-01

    Mesoamerica (the countries from Mexico to Colombia) has been identified by IPCC as a low-latitude, developing region at considerable risk to climate change. Furthermore, the complex topography of the region, and interactions with adjacent tropical oceans, makes understanding of potential climate change from global climate models alone very problematic. Statistical downscaling techniques for the region are not very robust, largely due to the lack of sufficient observations upon which to base the large-scale to small-scale relationships. Therefore, we have used the WRF regional climate model to dynamically downscale global results from a NCAR CCSM simulation employing the A2 emission scenario that was made for IPCC AR4. All of Mesoamerica is covered with a domain with a spatial resolution of 12 km, with selected high elevation regions of Mexico, Colombia, and Peru also covered by 4 km domains. A three-year simulation was made forced by NCEP reanalyses for the years 1991, 1992, and 1993. This run has been evaluated using actual station observations in addition to gridded datasets, in order to identify model strengths and weaknesses (biases) for this region. This comparison clearly demonstrated the need to properly resolve elevation, including both topographic heights and valleys. It also showed the difficulty that the model has in simulating extreme precipitation events, as it usually underestimates the actual amount. Additional five-year simulations were made forced with CCSM output for 2000-2004 (present-day control) and 2050-2054 (climate change scenario for the A2 emission scenario) to investigate potential climate change for the region. Summarizing key results, all land regions, except for a narrow strip along the Pacific coast of Mexico, showed a warming. This warming was largest (up to 3-4 deg C) in the highland regions and the Amazonian basin. The warming was less (generally 1-2 deg C) in the lowland and intermountain regions. Changes in precipitation strongly

  17. Abrupt change in climate and climate models

    Directory of Open Access Journals (Sweden)

    A. J. Pitman

    2006-01-01

    Full Text Available First, we review the evidence that abrupt climate changes have occurred in the past and then demonstrate that climate models have developing capacity to simulate many of these changes. In particular, the processes by which changes in the ocean circulation drive abrupt changes appear to be captured by climate models to a degree that is encouraging. The evidence that past changes in the ocean have driven abrupt change in terrestrial systems is also convincing, but these processes are only just beginning to be included in climate models. Second, we explore the likelihood that climate models can capture those abrupt changes in climate that may occur in the future due to the enhanced greenhouse effect. We note that existing evidence indicates that a major collapse of the thermohaline circulation seems unlikely in the 21st century, although very recent evidence suggests that a weakening may already be underway. We have confidence that current climate models can capture a weakening, but a collapse in the 21st century of the thermohaline circulation is not projected by climate models. Worrying evidence of instability in terrestrial carbon, from observations and modelling studies, is beginning to accumulate. Current climate models used by the Intergovernmental Panel on Climate Change for the 4th Assessment Report do not include these terrestrial carbon processes. We therefore can not make statements with any confidence regarding these changes. At present, the scale of the terrestrial carbon feedback is believed to be small enough that it does not significantly affect projections of warming during the first half of the 21st century. However, the uncertainties in how biological systems will respond to warming are sufficiently large to undermine confidence in this belief and point us to areas requiring significant additional work.

  18. Abrupt change in climate and climate models

    Directory of Open Access Journals (Sweden)

    A. J. Pitman

    2006-07-01

    Full Text Available First, we review the evidence that abrupt climate changes have occurred in the past and then demonstrate that climate models have developing capacity to simulate many of these changes. In particular, the processes by which changes in the ocean circulation drive abrupt changes appear to be captured by climate models to a degree that is encouraging. The evidence that past changes in the ocean have driven abrupt change in terrestrial systems is also convincing, but these processes are only just beginning to be included in climate models. Second, we explore the likelihood that climate models can capture those abrupt changes in climate that may occur in the future due to the enhanced greenhouse effect. We note that existing evidence indicates that a major collapse of the thermohaline circulate seems unlikely in the 21st century, although very recent evidence suggests that a weakening may already be underway. We have confidence that current climate models can capture a weakening, but a collapse of the thermohaline circulation in the 21st century is not projected by climate models. Worrying evidence of instability in terrestrial carbon, from observations and modelling studies, is beginning to accumulate. Current climate models used by the Intergovernmental Panel on Climate Change for the 4th Assessment Report do not include these terrestrial carbon processes. We therefore can not make statements with any confidence regarding these changes. At present, the scale of the terrestrial carbon feedback is believed to be small enough that it does not significantly affect projections of warming during the first half of the 21st century. However, the uncertainties in how biological systems will respond to warming are sufficiently large to undermine confidence in this belief and point us to areas requiring significant additional work.

  19. Evaluation of large-scale meteorological patterns associated with temperature extremes in the NARCCAP regional climate model simulations

    Science.gov (United States)

    Loikith, Paul C.; Waliser, Duane E.; Lee, Huikyo; Neelin, J. David; Lintner, Benjamin R.; McGinnis, Seth; Mearns, Linda O.; Kim, Jinwon

    2015-12-01

    Large-scale meteorological patterns (LSMPs) associated with temperature extremes are evaluated in a suite of regional climate model (RCM) simulations contributing to the North American Regional Climate Change Assessment Program. LSMPs are characterized through composites of surface air temperature, sea level pressure, and 500 hPa geopotential height anomalies concurrent with extreme temperature days. Six of the seventeen RCM simulations are driven by boundary conditions from reanalysis while the other eleven are driven by one of four global climate models (GCMs). Four illustrative case studies are analyzed in detail. Model fidelity in LSMP spatial representation is high for cold winter extremes near Chicago. Winter warm extremes are captured by most RCMs in northern California, with some notable exceptions. Model fidelity is lower for cool summer days near Houston and extreme summer heat events in the Ohio Valley. Physical interpretation of these patterns and identification of well-simulated cases, such as for Chicago, boosts confidence in the ability of these models to simulate days in the tails of the temperature distribution. Results appear consistent with the expectation that the ability of an RCM to reproduce a realistically shaped frequency distribution for temperature, especially at the tails, is related to its fidelity in simulating LMSPs. Each ensemble member is ranked for its ability to reproduce LSMPs associated with observed warm and cold extremes, identifying systematically high performing RCMs and the GCMs that provide superior boundary forcing. The methodology developed here provides a framework for identifying regions where further process-based evaluation would improve the understanding of simulation error and help guide future model improvement and downscaling efforts.

  20. Simulating the vegetation response to abrupt climate changes under glacial conditions with the ORCHIDEE/IPSL models

    Directory of Open Access Journals (Sweden)

    M.-N. Woillez

    2012-09-01

    Full Text Available The last glacial period has been punctuated by two types of abrupt climatic events, the Dansgaard-Oeschger (DO and Heinrich (HE events. These events, recorded in Greenland ice and in marine sediments, involved changes in the Atlantic Meridional Overturning Circulation (AMOC and led to major changes in the terrestrial biosphere.

    Here we use the dynamical global vegetation model ORCHIDEE to simulate the response of vegetation to abrupt changes in the AMOC strength. To do so, we force ORCHIDEE off-line with outputs from the IPSL_CM4 general circulation model, in which we have forced the AMOC to change by adding freshwater fluxes in the North Atlantic. We investigate the impact of a collapse and recovery of the AMOC, at different rates, and focus on Western Europe, where many pollen records are available to compare with.

    The impact of an AMOC collapse on the European mean temperatures and precipitations simulated by the GCM is relatively small but sufficient to drive an important regression of forests and expansion of grasses in ORCHIDEE, in qualitative agreement with pollen data for an HE event. On the contrary, a run with a rapid shift of the AMOC to an hyperactive state of 30 Sv, mimicking the warming phase of a DO event, does not exhibit a strong impact on the European vegetation compared to the glacial control state. For our model, simulating the impact of an HE event thus appears easier than simulating the abrupt transition towards the interstadial phase of a DO.

    For both a collapse or a recovery of the AMOC the vegetation starts to respond to climatic changes immediately but reaches equilibrium about 200 yr after the climate equilibrates, suggesting a possible bias in the climatic reconstructions based on pollen records, which assume equilibrium between climate and vegetation. However, our study does not take into account vegetation feedbacks on the atmosphere.

  1. Assessing the risk persistent drought using climate model simulations and paleoclimate data

    Science.gov (United States)

    Ault, Toby R.; Cole, Julia E.; Overpeck, Jonathan T.; Pederson, Gregory T.; Meko, David M.

    2014-01-01

    Projected changes in global rainfall patterns will likely alter water supplies and ecosystems in semiarid regions during the coming century. Instrumental and paleoclimate data indicate that natural hydroclimate fluctuations tend to be more energetic at low (multidecadal to multicentury) than at high (interannual) frequencies. State-of-the-art global climate models do not capture this characteristic of hydroclimate variability, suggesting that the models underestimate the risk of future persistent droughts. Methods are developed here for assessing the risk of such events in the coming century using climate model projections as well as observational (paleoclimate) information. Where instrumental and paleoclimate data are reliable, these methods may provide a more complete view of prolonged drought risk. In the U.S. Southwest, for instance, state-of-the-art climate model projections suggest the risk of a decade-scale megadrought in the coming century is less than 50%; the analysis herein suggests that the risk is at least 80%, and may be higher than 90% in certain areas. The likelihood of longer-lived events (>35 yr) is between 20% and 50%, and the risk of an unprecedented 50-yr megadrought is nonnegligible under the most severe warming scenario (5%–10%). These findings are important to consider as adaptation and mitigation strategies are developed to cope with regional impacts of climate change, where population growth is high and multidecadal megadrought—worse than anything seen during the last 2000 years—would pose unprecedented challenges to water resources in the region.

  2. Greenland ice sheet surface mass balance: evaluating simulations and making projections with regional climate models

    NARCIS (Netherlands)

    Rae, J.G.L.; Aðalgeirsdóttir, G.; Edwards, T.L.; Fettweis, X.; Gregory, J.M.; Hewitt, H.T.; Lowe, J.A.; Lucas-Picher, P.; Mottram, R.H.; Payne, A.J.; Ridley, J.K.; Shannon, S.R.; van de Berg, W.J.; van de Wal, R.S.W.; van den Broeke, M.R.

    2012-01-01

    Four high-resolution regional climate models (RCMs) have been set up for the area of Greenland, with the aim of providing future projections of Greenland ice sheet surface mass balance (SMB), and its contribution to sea level rise, with greater accuracy than is possible from coarser-resolution gener

  3. Testing the Ability of Numerical Model to Simulate Climate and Its Change With 4D-EOF Analysis

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The four-dimensional empirical orthogonal function (4D-EOF), which in reality is a simple combination of three-dimensional EOF (3D-EOF) and extended EOF (EEOF), is put forward in this paper to test the ability of numerical model to simulate climate and its change. The 4D-EOF analysis is able to reveal not only the horizontal characteristic pattern of analyzed variable, and its corresponding annual and inter-annual variations, but also the vertical structural characteristics. The method suggested is then used to analyze the monthly mean 100-, 500-, 700-, and 1000-hPa geopotential height fields (4941 grids and grid spacing 60 km) and their anomaly fields in 1989-1998 simulated by the MM5V3 from the RMIP (Regional Climate Model Inter-comparison Project for East Asia)-Ⅱ, as well as their counterparts (used as the observed fields)from the NCEP/NCAR re-analysis dataset in the same period. The ability of MM5V3 in simulating East Asian climate and its change is tested by comparing the 4D-EOF analysis results of the simulated and observed datasets. The comparative analyzed results show that the horizontal pattern of the first eigenvector of the observed monthly mean geopotential height fields and its vertical equivalent barotropic feature were well simulated; the simulations of the first two eigenvectors of the observed monthly mean geopotential height anomaly fields were also successful for their horizontal abnormal distributions and significant equivalent barotropic features in the vertical were well reproduced; and furthermore, the observed characteristics,such as the variation with height, the annual and inter-annual variations of the monthly mean geopotential height/anomaly fields were also well reflected in the simulation. Therefore, the 4D-EOF is able to comprehensively test numerical model's ability of simulating the climate and its change, and the simulation ability of MM5V3 for the climate and its change in East Asia in the 1990s was satisfactory.

  4. Potential for added value in precipitation simulated by high-resolution nested Regional Climate Models and observations

    Energy Technology Data Exchange (ETDEWEB)

    Di Luca, Alejandro; Laprise, Rene [Universite du Quebec a Montreal (UQAM), Centre ESCER (Etude et Simulation du Climat a l' Echelle Regionale), Departement des Sciences de la Terre et de l' Atmosphere, PK-6530, Succ. Centre-ville, B.P. 8888, Montreal, QC (Canada); De Elia, Ramon [Universite du Quebec a Montreal, Ouranos Consortium, Centre ESCER (Etude et Simulation du Climat a l' Echelle Regionale), Montreal (Canada)

    2012-03-15

    Regional Climate Models (RCMs) constitute the most often used method to perform affordable high-resolution regional climate simulations. The key issue in the evaluation of nested regional models is to determine whether RCM simulations improve the representation of climatic statistics compared to the driving data, that is, whether RCMs add value. In this study we examine a necessary condition that some climate statistics derived from the precipitation field must satisfy in order that the RCM technique can generate some added value: we focus on whether the climate statistics of interest contain some fine spatial-scale variability that would be absent on a coarser grid. The presence and magnitude of fine-scale precipitation variance required to adequately describe a given climate statistics will then be used to quantify the potential added value (PAV) of RCMs. Our results show that the PAV of RCMs is much higher for short temporal scales (e.g., 3-hourly data) than for long temporal scales (16-day average data) due to the filtering resulting from the time-averaging process. PAV is higher in warm season compared to cold season due to the higher proportion of precipitation falling from small-scale weather systems in the warm season. In regions of complex topography, the orographic forcing induces an extra component of PAV, no matter the season or the temporal scale considered. The PAV is also estimated using high-resolution datasets based on observations allowing the evaluation of the sensitivity of changing resolution in the real climate system. The results show that RCMs tend to reproduce relatively well the PAV compared to observations although showing an overestimation of the PAV in warm season and mountainous regions. (orig.)

  5. Simulation of the world ocean climate with a massively parallel numerical model

    Science.gov (United States)

    Ushakov, K. V.; Ibrayev, R. A.; Kalmykov, V. V.

    2015-07-01

    The INM-IO numerical World Ocean model is verified through the calculation of the model ocean climate. The numerical experiment was conducted for a period of 500 years following the CORE-I protocol. We analyze some basic elements of the large-scale ocean circulation and local and integral characteristics of the model solution. The model limitations and ways they are overcome are described. The results generally fit the level of leading models. This experiment is a necessary step preceding the transition to high-resolution diagnostic and prognostic calculations of the state of the World Ocean and its individual basins.

  6. SUNYA Regional Climate Model Simulations of East Asia Summer Monsoon: Effects of Cloud Vertical Structure on the Surface Energy Balance

    Directory of Open Access Journals (Sweden)

    Wei Gong Wei-Chyung Wang

    2007-01-01

    Full Text Available We used the State University of New York at Albany (SUNYA regional climate model to study the effect of cloud vertical distribution in affecting the surface energy balance of the East Asia summer monsoon (EASM. Simulations were conducted for the summers of 1988 and 1989, during which large contrast in the intra-seasonal cloud radiative forcing (CRF was observed at the top of the atmosphere.

  7. The climatic mass balance of Svalbard glaciers: a 10-year simulation with a coupled atmosphere-glacier mass balance model

    Science.gov (United States)

    Aas, Kjetil S.; Dunse, Thorben; Collier, Emily; Schuler, Thomas V.; Berntsen, Terje K.; Kohler, Jack; Luks, Bartłomiej

    2016-05-01

    In this study we simulate the climatic mass balance of Svalbard glaciers with a coupled atmosphere-glacier model with 3 km grid spacing, from September 2003 to September 2013. We find a mean specific net mass balance of -257 mm w.e. yr-1, corresponding to a mean annual mass loss of about 8.7 Gt, with large interannual variability. Our results are compared with a comprehensive set of mass balance, meteorological, and satellite measurements. Model temperature biases of 0.19 and -1.9 °C are found at two glacier automatic weather station sites. Simulated climatic mass balance is mostly within about 100 mm w.e. yr-1 of stake measurements, and simulated winter accumulation at the Austfonna ice cap shows mean absolute errors of 47 and 67 mm w.e. yr-1 when compared to radar-derived values for the selected years 2004 and 2006. Comparison of modeled surface height changes from 2003 to 2008, and satellite altimetry reveals good agreement in both mean values and regional differences. The largest deviations from observations are found for winter accumulation at Hansbreen (up to around 1000 mm w.e. yr-1), a site where sub-grid topography and wind redistribution of snow are important factors. Comparison with simulations using 9 km grid spacing reveal considerable differences on regional and local scales. In addition, 3 km grid spacing allows for a much more detailed comparison with observations than what is possible with 9 km grid spacing. Further decreasing the grid spacing to 1 km appears to be less significant, although in general precipitation amounts increase with resolution. Altogether, the model compares well with observations and offers possibilities for studying glacier climatic mass balance on Svalbard both historically as well as based on climate projections.

  8. Possible Influence of the Cultivated Land Reclamation on Surface Climate in India: A WRF Model Based Simulation

    Directory of Open Access Journals (Sweden)

    Yi Qu

    2013-01-01

    Full Text Available Land use/cover change (LUCC has become one of the most important factors for the global climate change. As one of the major types of LUCC, cultivated land reclamation also has impacts on regional climate change. Most of the previous studies focused on the correlation and simulation analysis of historical LUCC and climate change, with few explorations for the impacts of future LUCC on regional climate, especially impacts of the cultivated land reclamation. This study used the Weather Research and Forecasting (WRF model to forecast the changes of energy flux and temperature based on the future cultivated land reclamation in India and then analyzed the impacts of cultivated land reclamation on climate change. The results show that cultivated land reclamation will lead to a large amount of land conversions, which will overall result in the increase in latent heat flux of regional surface as well as the decrease in sensible heat flux and further lead to changes of regional average temperature. Furthermore, the impact on climate change is seasonally different. The cultivated land reclamation mainly leads to a temperature decrease in the summer, while it leads to a temperature increase in the winter.

  9. On the role of domain size and resolution in the simulations with the HIRHAM region climate model

    DEFF Research Database (Denmark)

    Larsen, Morten Andreas Dahl; Thejll, Peter; Christensen, Jens H.;

    2013-01-01

    We investigate the simulated temperature and precipitation of the HIRHAM regional climate model using systematic variations in domain size, resolution and detailed location in a total of eight simulations. HIRHAM was forced by ERA-Interim boundary data and the simulations focused on higher...... resolutions in the range of 5.5–12 km. HIRHAM outputs of seasonal precipitation and temperature were assessed by calculating distributed model errors against a higher resolution data set covering Denmark and a 0.25° resolution data set covering Europe. Furthermore the simulations were statistically tested......, the temperature errors were more highly significant than precipitation. In similarly sized domains, 12 of 16 combinations of variables, observation validation data and seasons showed better results for the highest resolution domain, but generally the most significant improvements were seen when varying the domain...

  10. CoFoLaMo: Comparing forest landscape model simulations under different climate, interaction- and land use scenarios

    Science.gov (United States)

    Lischke, Heike; Speich, Matthias; Schmatz, Dirk; Vacchiano, Giorgio; Mairota, Paola; Leronni, Vincenzo; Schuler, Laura; Bugmann, Harald; Bruna, Josef; Thom, Dominik; Seidl, Rupert; Reineking, Björn

    2016-04-01

    Forests play an important role in the global climate system, and are themselves strongly affected by the changing climate. Forest dynamics do not only act at the stand scale, but are also influenced by larger scale drivers, such as landscape management, and by spatial interactions, such as fire spread or seed dispersal. Forest landscape models run on areas larger than a stand and interact spatially and thus are capable of taking into account these effects. We present the setup of the forest landscape model intercomparison CoFoLaMo (which is based on the setup of the ISI-MIP forest stand model comparison), where we examine several forest landscape models- LandClim, ForHyCS, TreeMig, LANDIS II and iLand - in terms of their usefulness for different kinds of applications. We compare the models with respect to their general approach, scales, resolution, and data requirements, processes, interactions, drivers, disturbances, outputs, and uncertainties. We run simulations in different test regions across temperate Europe, e.g., in the northern(Davos)and southern Alps (Valle d'Aosta), the Bavarian Forest and southern Italy (Puglia). Climate drivers (mostly daily T and P) are downscaled to 100 m resolution in the respective regions. For spinup and model testing we use past observed climate, extrapolated back to 1600 AD, for future simulations a set of different RCPs of different model chains from the ISI-MIP community. For model testing we use appropriate spatial forest data available for each region, ranging from NFI data, terrestrial vegetation type maps, or remote sensing derived forest types and high resolution canopy height. To address the landscape aspect of the models, we compare them in different scenarios of spatially interacting disturbances, spatial interactions by seed dispersal and land use.

  11. Modeling of hydrologic conditions and solute movement in processed oil shale waste embankments under simulated climatic conditions

    Energy Technology Data Exchange (ETDEWEB)

    Reeves, T.L.; Turner, J.P.; Hasfurther, V.R.; Skinner, Q.D.

    1992-06-01

    The scope of this program is to study interacting hydrologic, geotechnical, and chemical factors affecting the behavior and disposal of combusted processed oil shale. The research combines bench-scale testing with large scale research sufficient to describe commercial scale embankment behavior. The large scale approach was accomplished by establishing five lysimeters, each 7.3 [times] 3.0 [times] 3.0 m deep, filled with processed oil shale that has been retorted and combusted by the Lurgi-Ruhrgas (Lurgi) process. Approximately 400 tons of Lurgi processed oil shale waste was provided by RBOSC to carry out this study. Research objectives were designed to evaluate hydrologic, geotechnical, and chemical properties and conditions which would affect the design and performance of large-scale embankments. The objectives of this research are: assess the unsaturated movement and redistribution of water and the development of potential saturated zones and drainage in disposed processed oil shale under natural and simulated climatic conditions; assess the unsaturated movement of solubles and major chemical constituents in disposed processed oil shale under natural and simulated climatic conditions; assess the physical and constitutive properties of the processed oil shale and determine potential changes in these properties caused by disposal and weathering by natural and simulated climatic conditions; assess the use of previously developed computer model(s) to describe the infiltration, unsaturated movement, redistribution, and drainage of water in disposed processed oil shale; evaluate the stability of field scale processed oil shale solid waste embankments using computer models.

  12. Modeling of hydrologic conditions and solute movement in processed oil shale waste embankments under simulated climatic conditions

    Energy Technology Data Exchange (ETDEWEB)

    Reeves, T.L.; Turner, J.P.; Hasfurther, V.R.; Skinner, Q.D.

    1992-06-01

    The scope of this program is to study interacting hydrologic, geotechnical, and chemical factors affecting the behavior and disposal of combusted processed oil shale. The research combines bench-scale testing with large scale research sufficient to describe commercial scale embankment behavior. The large scale approach was accomplished by establishing five lysimeters, each 7.3 {times} 3.0 {times} 3.0 m deep, filled with processed oil shale that has been retorted and combusted by the Lurgi-Ruhrgas (Lurgi) process. Approximately 400 tons of Lurgi processed oil shale waste was provided by RBOSC to carry out this study. Research objectives were designed to evaluate hydrologic, geotechnical, and chemical properties and conditions which would affect the design and performance of large-scale embankments. The objectives of this research are: assess the unsaturated movement and redistribution of water and the development of potential saturated zones and drainage in disposed processed oil shale under natural and simulated climatic conditions; assess the unsaturated movement of solubles and major chemical constituents in disposed processed oil shale under natural and simulated climatic conditions; assess the physical and constitutive properties of the processed oil shale and determine potential changes in these properties caused by disposal and weathering by natural and simulated climatic conditions; assess the use of previously developed computer model(s) to describe the infiltration, unsaturated movement, redistribution, and drainage of water in disposed processed oil shale; evaluate the stability of field scale processed oil shale solid waste embankments using computer models.

  13. Variation of Surface Temperature during the Last Millennium in a Simulation with the FGOALS-g1 Climate System Model

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jie; Laurent LI; ZHOU Tianjun; XIN Xiaoge

    2013-01-01

    A reasonable past millennial climate simulation relies heavily on the specified external forcings,including both natural and anthropogenic forcing agents.In this paper,we examine the surface temperature responses to specified external forcing agents in a millennium-scale transient climate simulation with the fast version of LASG IAP Flexible Global Ocean-Atmosphere-Land System model (FGOALS-gl) developed in the State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics,Institute of Atmospheric Physics (LASG/IAP).The model presents a reasonable performance in comparison with reconstructions of surface temperature.Differentiated from significant changes in the 20th century at the global scale,changes during the natural-forcing-dominant period are mainly manifested in the Northern Hemisphere.Seasonally,modeled significant changes are more pronounced during the wintertime at higher latitudes.This may be a manifestation of polar amplification associated with sea-ice-temperature positive feedback.The climate responses to total external forcings can explain about half of the climate variance during the whole millennium period,especially at decadal timescales.Surface temperature in the Antarctic shows heterogeneous and insignificant changes during the preindustrial period and the climate response to external forcings is undetectable due to the strong internal variability.The model response to specified external forcings is modulated by cloud radiative forcing (CRF).The CRF acts against the fluctuations of external forcings.Effects of clouds are manifested in shortwave radiation by changes in cloud water during the natural-forcing-dominant period,but mainly in longwave radiation by a decrease in cloud amount in the anthropogenic-forcing-dominant period.

  14. Validation of precipitation over Japan during 1985-2004 simulated by three regional climate models and two multi-model ensemble means

    Energy Technology Data Exchange (ETDEWEB)

    Ishizaki, Yasuhiro [Meteorological Research Institute, Tsukuba (Japan); National Institute for Environmental Studies, Tsukuba (Japan); Nakaegawa, Toshiyuki; Takayabu, Izuru [Meteorological Research Institute, Tsukuba (Japan)

    2012-07-15

    We dynamically downscaled Japanese reanalysis data (JRA-25) for 60 regions of Japan using three regional climate models (RCMs): the Non-Hydrostatic Regional Climate Model (NHRCM), modified RAMS version 4.3 (NRAMS), and modified Weather Research and Forecasting model (TWRF). We validated their simulations of the precipitation climatology and interannual variations of summer and winter precipitation. We also validated precipitation for two multi-model ensemble means: the arithmetic ensemble mean (AEM) and an ensemble mean weighted according to model reliability. In the 60 regions NRAMS simulated both the winter and summer climatological precipitation better than JRA-25, and NHRCM simulated the wintertime precipitation better than JRA-25. TWRF, however, overestimated precipitation in the 60 regions in both the winter and summer, and NHRCM overestimated precipitation in the summer. The three RCMs simulated interannual variations, particularly summer precipitation, better than JRA-25. AEM simulated both climatological precipitation and interannual variations during the two seasons more realistically than JRA-25 and the three RCMs overall, but the best RCM was often superior to the AEM result. In contrast, the weighted ensemble mean skills were usually superior to those of the best RCM. Thus, both RCMs and multi-model ensemble means, especially multi-model ensemble means weighted according to model reliability, are powerful tools for simulating seasonal and interannual variability of precipitation in Japan under the current climate. (orig.)

  15. Simulated Future Air Temperature and Precipitation Climatology and Variability in the Mediterranean Basin by Using Downscaled Global Climate Model Outputs

    Science.gov (United States)

    Ozturk, Tugba; Pelin Ceber, Zeynep; Türkeş, Murat; Kurnaz, M. Levent

    2014-05-01

    The Mediterranean Basin is one of the regions that shall be affected most by the impacts of the future climate changes on temperature regime including changes in heat waves intensity and frequency, seasonal and interannual precipitation variability including changes in summer dryness and drought events, and hydrology and water resources. In this study, projected future changes in mean air temperature and precipitation climatology and inter-annual variability over the Mediterranean region were simulated. For performing this aim, the future changes in annual and seasonal averages for the future period of 2070-2100 with respect to the period from 1970 to 2000 were investigated. Global climate model outputs of the World Climate Research Program's (WCRP's) Coupled Model Intercomparison Project Phase 3 (CMIP3) multi-model dataset were used. SRES A2, A1B and B1 emission scenarios' outputs of the Intergovernmental Panel on Climate Change (IPCC) were used in future climate model projections. Future surface mean air temperatures of the larger Mediterranean basin increase mostly in summer and least in winter, and precipitation amounts decreases in all seasons at almost all parts of the basin. Future climate signals for surface air temperatures and precipitation totals will be much larger than the inter-model standard deviation. Inter-annual temperature variability increases evidently in summer season and decreases in the northern part of the domain in the winter season, while precipitation variability increases in almost all parts of domain. Probability distribution functions are found to be shifted and flattened for future period compared to reference period. This indicates that occurrence frequency and intensity of extreme weather conditions will increase in the future period. This work has been supported by Bogazici University BAP under project number 7362. One of the authors (MLK) was partially supported by Mercator-IPC Fellowship Program.

  16. Simulation of the last glacial cycle with a coupled climate ice-sheet model of intermediate complexity

    Directory of Open Access Journals (Sweden)

    A. Ganopolski

    2010-04-01

    Full Text Available A new version of the Earth system model of intermediate complexity, CLIMBER-2, which includes the three-dimensional polythermal ice-sheet model SICOPOLIS, is used to simulate the last glacial cycle forced by variations of the Earth's orbital parameters and atmospheric concentration of major greenhouse gases. The climate and ice-sheet components of the model are coupled bi-directionally through a physically-based surface energy and mass balance interface. The model accounts for the time-dependent effect of aeolian dust on planetary and snow albedo. The model successfully simulates the temporal and spatial dynamics of the major Northern Hemisphere (NH ice sheets, including rapid glacial inception and strong asymmetry between the ice-sheet growth phase and glacial termination. Spatial extent and elevation of the ice sheets during the last glacial maximum agree reasonably well with palaeoclimate reconstructions. A suite of sensitivity experiments demonstrates that simulated ice-sheet evolution during the last glacial cycle is very sensitive to some parameters of the surface energy and mass-balance interface and dust module. The possibility of a considerable acceleration of the climate ice-sheet model is discussed.

  17. Contribution of the North Atlantic subtropical high to regional climate model (RCM) skill in simulating southeastern United States summer precipitation

    Science.gov (United States)

    Li, Laifang; Li, Wenhong; Jin, Jiming

    2015-07-01

    This study assesses the skill of advanced regional climate models (RCMs) in simulating southeastern United States (SE US) summer precipitation and explores the physical mechanisms responsible for the simulation skill at a process level. Analysis of the RCM output for the North American Regional Climate Change Assessment Program indicates that the RCM simulations of summer precipitation show the largest biases and a remarkable spread over the SE US compared to other regions in the contiguous US. The causes of such a spread are investigated by performing simulations using the Weather Research and Forecasting (WRF) model, a next-generation RCM developed by the US National Center for Atmospheric Research. The results show that the simulated biases in SE US summer precipitation are due mainly to the misrepresentation of the modeled North Atlantic subtropical high (NASH) western ridge. In the WRF simulations, the NASH western ridge shifts 7° northwestward when compared to that in the reanalysis ensemble, leading to a dry bias in the simulated summer precipitation according to the relationship between the NASH western ridge and summer precipitation over the southeast. Experiments utilizing the four dimensional data assimilation technique further suggest that the improved representation of the circulation patterns (i.e., wind fields) associated with the NASH western ridge substantially reduces the bias in the simulated SE US summer precipitation. Our analysis of circulation dynamics indicates that the NASH western ridge in the WRF simulations is significantly influenced by the simulated planetary boundary layer (PBL) processes over the Gulf of Mexico. Specifically, a decrease (increase) in the simulated PBL height tends to stabilize (destabilize) the lower troposphere over the Gulf of Mexico, and thus inhibits (favors) the onset and/or development of convection. Such changes in tropical convection induce a tropical-extratropical teleconnection pattern, which modulates the

  18. Climate and Habitability of Kepler 452b Simulated with a Fully Coupled Atmosphere–Ocean General Circulation Model

    Science.gov (United States)

    Hu, Yongyun; Wang, Yuwei; Liu, Yonggang; Yang, Jun

    2017-01-01

    The discovery of Kepler 452b is a milestone in searching for habitable exoplanets. While it has been suggested that Kepler 452b is the first Earth-like exoplanet discovered in the habitable zone of a Sun-like star, its climate states and habitability require quantitative studies. Here, we first use a three-dimensional fully coupled atmosphere–ocean climate model to study the climate and habitability of an exoplanet around a Sun-like star. Our simulations show that Kepler 452b is habitable if CO2 concentrations in its atmosphere are comparable or lower than that in the present-day Earth atmosphere. However, our simulations also suggest that Kepler 452b can become too hot to be habitable if there is the lack of silicate weathering to limit CO2 concentrations in the atmosphere. We also address whether Kepler 452b could retain its water inventory after 6.0 billion years of lifetime. These results in the present Letter will provide insights about climate and habitability for other undiscovered exoplanets similar to Kepler 452b, which may be observable by future observational missions.

  19. The amplitude of decadal to multidecadal variability in precipitation simulated by state-of-the-art climate models

    Science.gov (United States)

    Ault, T. R.; Cole, J. E.; St. George, S.

    2012-11-01

    We assess the magnitude of decadal to multidecadal (D2M) variability in Climate Model Intercomparison Project 5 (CMIP5) simulations that will be used to understand, and plan for, climate change as part of the Intergovernmental Panel on Climate Change's 5th Assessment Report. Model performance on D2M timescales is evaluated using metrics designed to characterize the relative and absolute magnitude of variability at these frequencies. In observational data, we find that between 10% and 35% of the total variance occurs on D2M timescales. Regions characterized by the high end of this range include Africa, Australia, western North America, and the Amazon region of South America. In these areas D2M fluctuations are especially prominent and linked to prolonged drought. D2M fluctuations account for considerably less of the total variance (between 5% and 15%) in the CMIP5 archive of historical (1850-2005) simulations. The discrepancy between observation and model based estimates of D2M prominence reflects two features of the CMIP5 archive. First, interannual components of variability are generally too energetic. Second, decadal components are too weak in several key regions. Our findings imply that projections of the future lack sufficient decadal variability, presenting a limited view of prolonged drought and pluvial risk.

  20. Interpreting Recent Global-Mean Temperature Changes in the Lower Stratosphere Simulated by Climate Models

    Science.gov (United States)

    Geller, M. A.; Zhou, T.; Martin, W. G. K.; Song, H.; Wang, S.; Nazarenko, L.; Lo, K. W. K.

    2014-12-01

    It has been suggested that state-of-the-art climate models, both with interactive chemistry and without interactive chemistry (CCMVal-2 and CMIP5) do not reproduce the observed lower stratosphere temperature anomalies that are observed by satellite microwave sounding instruments. We find that making two changes in the analysis can eliminate this disagreement. One is a change in the definition of the temperature anomalies as being zero for the 4-year mean (1979-1982) at the beginning of the data and modeling analysis period. Such a definition of the zero temperature anomaly does not take into proper account that observations over a relatively short period represent a single realization of several possible climate states, and thus this zero anomaly definition can be misleading when comparing anomalies from observations and models. The other change is our taking into account all CMIP-5 and CCMVal-2 model runs that ran realistic scenarios for the period 1979-2005. With these two changes in the analysis, we conclude that temperature changes from both CMIP-5 and CCMVal-2 models agree well with MSU-4 observations over the period 1979-2005.

  1. Evaluation of precipitation over an oceanic region of Japan in convection-permitting regional climate model simulations

    Science.gov (United States)

    Murata, Akihiko; Sasaki, Hidetaka; Kawase, Hiroaki; Nosaka, Masaya

    2017-03-01

    We investigated the performance of a convection-permitting regional climate model with respect to precipitation in the present climate around the southwestern oceanic region of Japan. The effects of explicit representation of convective processes without cumulus parameterization can be properly estimated by using a model domain without complex topography or convoluted coastlines. The amounts of annual and monthly precipitation and the frequencies of daily and hourly precipitation were well reproduced by the convection-permitting model with a 2-km grid spacing, and its performance was better than that of a model with a coarser mesh. In particular, the frequencies of hourly precipitation in the convection-permitting simulation matched the observed frequencies for precipitation intensities below 20 mm h-1. Above intensities of 20 mm h-1, however, the convection-permitting model tended to overestimate the frequency of hourly precipitation. To explore the mechanism of this overestimation of heavy hourly precipitation, the sensitivity of the frequency distribution of precipitation to the horizontal resolution was tested by changing the horizontal grid spacing of the model from 2 to 4 km and then 1.5 km. The results showed that the overestimation was increased when the horizontal resolution was coarser, owing to spurious grid-scale precipitation, which causes heavy precipitation to be highly concentrated in a single grid. This spurious grid-scale precipitation may be caused by insufficient representation of convective downdrafts in convection-permitting simulations by models with coarser resolutions.

  2. DUE PERMAFROST: A Circumpolar Remote Sensing Service for Permafrost - Evaluation Case Studies and Intercomparison with Regional Climate Model Simulations

    Science.gov (United States)

    Heim, B.; Bartsch, A.; Elger, K. K.; Rinke, A.; Matthes, H.; Zhou, X.; Klehmet, K.; Buchhorn, M.; Soliman, A. S.; Duguay, C. R.

    2013-12-01

    stakeholders and the IPA, and the ongoing evaluation of the remote sensing derived products make the DUE Permafrost products accepted by the scientific community. The Helmholtz Climate Initiative REKLIM (Regionale KlimaAnderungen/Regional climate change) is a climate research program where regional observations and process studies are coupled with model simulations (http://www.reklim.de/en/home/). The ESA DUE Permafrost User workshops initiated the use of the DUE time series within the REKLIM framework for inter-comparison experiments in order to assist the evaluation of calculated parameter fields of models. Within the REKLIM framework we spatio-temporally compare the geophysical surface parameters simulated by regional climate models with the spatio-temporal variability of Earth Observational remote sensing products. Earth Observational remote sensing products are: DUE Permafrost, DUE GlobSnow (http://www.globsnow.info) and the MODIS albedo product (MOD 43). We show intercomparison substudies on simulated fields of surface temperature and ground frozen, non-frozen state simulated by the regional climate models HIRHAM for the circumpolar domain and COSMO-CLM for Central Siberia.

  3. Sensitivity of sea ice and ocean simulations to sea ice salinity in a coupled global climate model

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The impacts of the spatiotemporal variations of sea ice salinity on sea ice and ocean characteristics have not been studied in detail, as the existing climate models neglect or misrepresent this process. To address this issue, this paper formulated a parameterization with more realistic sea ice salinity budget, and examined the sensitivity of sea ice and ocean simulations to the ice salinity variations and associated salt flux into the ocean using a coupled global climate model. Results show that the inclusion of such a parameterization leads to an increase and thickening of sea ice in the Eurasian Arctic and within the ice pack in the Antarctic circumpolar region, and a weakening of the North Atlantic Deep Water and a strengthening of the Antarctic Bottom Water. The atmospheric responses associated with the ice changes were also discussed.

  4. Evaluation of water balance components in the Elbe river catchment simulated by the regional climate model CCLM

    Directory of Open Access Journals (Sweden)

    Jan Volkholz

    2014-12-01

    Full Text Available For investigations of feedbacks between the hydrological cycle and the climate system, we assess the performance of the regional climate model CCLM in reconstructing the water balance of the Elbe river catchment. To this end long-term mean precipitation, evapotranspiration and runoff are evaluated. Extremes (90th percentile are also considered in the case of precipitation. The data are provided by a CCLM present-day simulation for Europe that was driven by large-scale global reanalyses. The quality of the model results is analyzed with respect to suitable reference data for the period 1970 to 1999. The principal components of the hydrological cycle and their seasonal variations were captured well. Basin accumulated, averaged daily precipitation, evapotranspiration and runoff differ by no more than 10 % from observations. Larger deviations occur mainly in summer, and at specific areas.

  5. Solar cycle variations of stratospheric ozone and temperature in simulations of a coupled chemistry-climate model

    Science.gov (United States)

    Austin, J.; Hood, L. L.; Soukharev, B. E.

    2007-03-01

    The results from three 45-year simulations of a coupled chemistry climate model are analysed for solar cycle influences on ozone and temperature. The simulations include UV forcing at the top of the atmosphere, which includes a generic 27-day solar rotation effect as well as the observed monthly values of the solar fluxes. The results are analysed for the 27-day and 11-year cycles in temperature and ozone. In accordance with previous results, the 27-day cycle results are in good qualitative agreement with observations, particularly for ozone. However, the results show significant variations, typically a factor of two or more in sensitivity to solar flux, depending on the solar cycle. In the lower and middle stratosphere we show good agreement also between the modelled and observed 11-year cycle results for the ozone vertical profile averaged over low latitudes. In particular, the minimum in solar response near 20 hPa is well simulated. In comparison, experiments of the model with fixed solar phase (solar maximum/solar mean) and climatological sea surface temperatures lead to a poorer simulation of the solar response in the ozone vertical profile, indicating the need for variable phase simulations in solar sensitivity experiments. The role of sea surface temperatures and tropical upwelling in simulating the ozone minimum response are also discussed.

  6. Solar cycle variations of stratospheric ozone and temperature in simulations of a coupled chemistry-climate model

    Directory of Open Access Journals (Sweden)

    J. Austin

    2007-01-01

    Full Text Available The results from three 45-year simulations of a coupled chemistry climate model are analysed for solar cycle influences on ozone and temperature. The simulations include UV forcing at the top of the atmosphere, which includes a generic 27-day solar rotation effect as well as the observed monthly values of the solar fluxes. The results are analysed for the 27-day and 11-year cycles in temperature and ozone. In accordance with previous results, the 27-day cycle results are in good qualitative agreement with observations, particularly for ozone. However, the results show significant variations, typically a factor of two or more in sensitivity to solar flux, depending on the solar cycle. In the lower and middle stratosphere we show good agreement also between the modelled and observed 11-year cycle results for the ozone vertical profile averaged over low latitudes. In particular, the minimum in solar response near 20 hPa is well simulated. In comparison, experiments of the model with fixed solar phase (solar maximum/solar mean and climatological sea surface temperatures lead to a poorer simulation of the solar response in the ozone vertical profile, indicating the need for variable phase simulations in solar sensitivity experiments. The role of sea surface temperatures and tropical upwelling in simulating the ozone minimum response are also discussed.

  7. Soil erosion under climate change in Great Britain: long-term simulations using high-resolution regional models

    Science.gov (United States)

    Ciampalini, Rossano; Kendon, Elizabeth; Constantine, José Antonio; Schindewolf, Marcus; Hall, Ian

    2016-04-01

    Twenty-first century climate change simulations for Great Britain reveal an increase in heavy precipitation that may lead to widespread soil loss and reduced soil carbon stores by increasing the likelihood of surface runoff. We find the quality and resolution of the simulated rainfall used to drive soil loss variation can widely influence the results. Hourly high definition rainfall simulations from a 1.5km resolution regional climate model are used to examine the soil erosion response in two UK catchments. The catchments have different sensitivity to soil erosion. "Rother" in West Sussex, England, reports some of the most erosive events that have been observed during the last 50 years in the UK. "Conwy" in North Wales, is resilient to soil erosion because of the abundant natural vegetation cover and very limited agricultural practises. We modelled with Erosion3D to check variations in soil erosion as influenced by climate variations for the periods 1996-2009 and 2086-2099. Our results indicate the Rother catchment is the most erosive, while the Conwy catchment is confirmed as the more resilient to soil erosion. The values of the reference-base period are consistent with the values of those locally observed in the previous decades. A soil erosion comparison for the two periods shows an increasing of sediment production (off-site erosion) for the end of the century at about 27% in the Rother catchment and about 50% for the Conwy catchment. The results, thanks to high-definition rainfall predictions, throw some light on the effect of climatic change effects in Great Britain.

  8. Spatial spin-up of fine scales in a regional climate model simulation driven by low-resolution boundary conditions

    Science.gov (United States)

    Matte, Dominic; Laprise, René; Thériault, Julie M.; Lucas-Picher, Philippe

    2016-09-01

    In regional climate modelling, it is well known that domains should be neither too large to avoid a large departure from the driving data, nor too small to provide a sufficient distance from the lateral inflow boundary to allow the full development of the small-scale (SS) features permitted by the finer resolution. Although most practitioners of dynamical downscaling are well aware that the jump of resolution between the lateral boundary condition (LBC) driving data and the nested regional climate model affects the simulated climate, this issue has not been fully investigated. In principle, as the jump of resolution becomes larger, the region of interest in the limited-area domain should be located further away from the lateral inflow boundary to allow the full development of the SS features. A careless choice of domain might result in a suboptimal use of the full finer resolution potential to develop fine-scale features. To address this issue, regional climate model (RCM) simulations using various resolution driving data are compared following the perfect-prognostic Big-Brother protocol. Several experiments were carried out to evaluate the width of the spin-up region (i.e. the distance between the lateral inflow boundary and the domain of interest required for the full development of SS transient eddies) as a function of the RCM and LBC resolutions, as well as the resolution jump. The spin-up distance turns out to be a function of the LBC resolution only, independent of the RCM resolution. When varying the RCM resolution for a given resolution jump, it is found that the spin-up distance corresponds to a fixed number of RCM grid points that is a function of resolution jump only. These findings can serve a useful purpose to guide the choice of domain and RCM configuration for an optimal development of the small scales allowed by the increased resolution of the nested model.

  9. Evaluation of regional climate model simulations versus gridded observed and regional reanalysis products using a combined weighting scheme

    Energy Technology Data Exchange (ETDEWEB)

    Eum, Hyung-Il; Laprise, Rene [University of Quebec at Montreal, ESCER (Etude et Simulation du Climat a l' Echelle Regionale), Montreal, QC (Canada); Gachon, Philippe [University of Quebec at Montreal, ESCER (Etude et Simulation du Climat a l' Echelle Regionale), Montreal, QC (Canada); Environment Canada, Adaptation and Impacts Research Section, Climate Research Division, Montreal, QC (Canada); Ouarda, Taha [University of Quebec, INRS-ETE (Institut National de la Recherche Scientifique, Centre Eau-Terre-Environnement), Quebec, QC (Canada)

    2012-04-15

    This study presents a combined weighting scheme which contains five attributes that reflect accuracy of climate data, i.e. short-term (daily), mid-term (annual), and long-term (decadal) timescales, as well as spatial pattern, and extreme values, as simulated from Regional Climate Models (RCMs) with respect to observed and regional reanalysis products. Southern areas of Quebec and Ontario provinces in Canada are used for the study area. Three series of simulation from two different versions of the Canadian RCM (CRCM4.1.1, and CRCM4.2.3) are employed over 23 years from 1979 to 2001, driven by both NCEP and ERA40 global reanalysis products. One series of regional reanalysis dataset (i.e. NARR) over North America is also used as reference for comparison and validation purpose, as well as gridded historical observed daily data of precipitation and temperatures, both series have been beforehand interpolated on the CRCM 45-km grid resolution. Monthly weighting factors are calculated and then combined into four seasons to reflect seasonal variability of climate data accuracy. In addition, this study generates weight averaged references (WARs) with different weighting factors and ensemble size as new reference climate data set. The simulation results indicate that the NARR is in general superior to the CRCM simulated precipitation values, but the CRCM4.1.1 provides the highest weighting factors during the winter season. For minimum and maximum temperature, both the CRCM4.1.1 and the NARR products provide the highest weighting factors, respectively. The NARR provides more accurate short- and mid-term climate data, but the two versions of the CRCM provide more precise long-term data, spatial pattern and extreme events. Or study confirms also that the global reanalysis data (i.e. NCEP vs. ERA40) used as boundary conditions in the CRCM runs has non-negligible effects on the accuracy of CRCM simulated precipitation and temperature values. In addition, this study demonstrates

  10. Stochastic Climate Theory and Modelling

    CERN Document Server

    Franzke, Christian L E; Berner, Judith; Williams, Paul D; Lucarini, Valerio

    2014-01-01

    Stochastic methods are a crucial area in contemporary climate research and are increasingly being used in comprehensive weather and climate prediction models as well as reduced order climate models. Stochastic methods are used as subgrid-scale parameterizations as well as for model error representation, uncertainty quantification, data assimilation and ensemble prediction. The need to use stochastic approaches in weather and climate models arises because we still cannot resolve all necessary processes and scales in comprehensive numerical weather and climate prediction models. In many practical applications one is mainly interested in the largest and potentially predictable scales and not necessarily in the small and fast scales. For instance, reduced order models can simulate and predict large scale modes. Statistical mechanics and dynamical systems theory suggest that in reduced order models the impact of unresolved degrees of freedom can be represented by suitable combinations of deterministic and stochast...

  11. Chemistry and dynamics of the Arctic winter 2015/2016: Simulations with the Chemistry-Climate Model EMAC

    Science.gov (United States)

    Khosrawi, Farahnaz; Kirner, Ole; Sinnhuber, Bjoern-Martin; Ruhnke, Roland; Hoepfner, Michael; Woiwode, Wolfgang; Oelhaf, Hermann; Santee, Michelle L.; Manney, Gloria L.; Froidevaux, Lucien; Murtagh, Donal; Braesicke, Peter

    2016-04-01

    Model simulations of the Arctic winter 2015/2016 were performed with the atmospheric chemistry-climate model ECHAM5/MESSy Atmospheric Chemistry (EMAC) for the POLSTRACC (Polar Stratosphere in a Changing Climate) project. The POLSTRACC project is a HALO mission (High Altitude and LOng Range Research Aircraft) that aims to investigate the structure, composition and evolution of the Arctic Upper Troposphere Lower Stratosphere (UTLS) in a changing climate. Especially, the chemical and physical processes involved in Arctic stratospheric ozone depletion, transport and mixing processes in the UTLS at high latitudes, polar stratospheric clouds as well as cirrus clouds are investigated. The model simulations were performed with a resolution of T42L90, corresponding to a quadratic Gaussian grid of approximately 2.8°× 2.8° degrees in latitude and longitude, and 90 vertical layers from the surface up to 0.01 hPa (approx. 80 km). A Newtonian relaxation technique of the prognostic variables temperature, vorticity, divergence and surface pressure towards ECMWF data was applied above the boundary layer and below 10 hPa, in order to nudge the model dynamics towards the observed meteorology. During the Arctic winter 2015/2016 a stable vortex formed in early December, with a cold pool where temperatures reached below the Nitric Acid Trihydrate (NAT) existence temperature of 195 K, thus allowing Polar Stratospheric Clouds (PSCs) to form. The early winter has been exceptionally cold and satellite observations indicate that sedimenting PSC particles have lead to denitrification as well as dehydration of stratospheric layers. In this presentation an overview of the chemistry and dynamics of the Arctic winter 2015/2016 as simulated with EMAC will be given and comparisons to satellite observations such as e.g. Aura/MLS and Odin/SMR will be shown.

  12. Simulation of Asian Monsoon Seasonal Variations with Climate Model R42L9/LASG

    Institute of Scientific and Technical Information of China (English)

    王在志; 吴国雄; 吴统文; 宇如聪

    2004-01-01

    The seasonal variations of the Asian monsoon were explored by applying the atmospheric general circulation model R42L9 that was developed recently at the State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics, Chinese Academy of Sciences (LASG/IAP/CAS). The 20-yr (1979-1998) simulation was done using the prescribed20-yr monthly SST and sea-ice data as required by Atmospheric Model Intercomparison Project (AMIP)Ⅱ in the model. The monthly precipitation and monsoon circulations were analyzed and compared with the observations to validate the model's performance in simulating the climatological mean and seasonal variations of the Asian monsoon. The results show that the model can capture the main features of the spatial distribution and the temporal evolution of precipitation in the Indian and East Asian monsoon areas. The model also reproduced the basic patterns of monsoon circulation. However, some biases exist in this model. The simulation of the heating over the Tibetan Plateau in summer was too strong. The overestimated heating caused a stronger East Asian monsoon and a weaker Indian monsoon than the observations. In the circulation fields, the South Asia high was stronger and located over the Tibetan Plateau. The western Pacific subtropical high was extended westward, which is in accordance with the observational results when the heating over the Tibetan Plateau is stronger. Consequently, the simulated rainfall around this area and in northwest China was heavier than in observations, but in the Indian monsoon area and west Pacific the rainfall was somewhat deficient.

  13. Impact of high resolution land surface initialization in Indian summer monsoon simulation using a regional climate model

    Science.gov (United States)

    Unnikrishnan, C. K.; Rajeevan, M.; Rao, S. Vijaya Bhaskara

    2016-06-01

    The direct impact of high resolution land surface initialization on the forecast bias in a regional climate model in recent years over Indian summer monsoon region is investigated. Two sets of regional climate model simulations are performed, one with a coarse resolution land surface initial conditions and second one used a high resolution land surface data for initial condition. The results show that all monsoon years respond differently to the high resolution land surface initialization. The drought monsoon year 2009 and extended break periods were more sensitive to the high resolution land surface initialization. These results suggest that the drought monsoon year predictions can be improved with high resolution land surface initialization. Result also shows that there are differences in the response to the land surface initialization within the monsoon season. Case studies of heat wave and a monsoon depression simulation show that, the model biases were also improved with high resolution land surface initialization. These results show the need for a better land surface initialization strategy in high resolution regional models for monsoon forecasting.

  14. Assessment of future scenarios for wind erosion sensitivity changes based on ALADIN and REMO regional climate model simulation data

    Directory of Open Access Journals (Sweden)

    Mezősi Gábor

    2016-07-01

    Full Text Available The changes in rate and pattern of wind erosion sensitivity due to climate change were investigated for 2021–2050 and 2071–2100 compared to the reference period (1961–1990 in Hungary. The sensitivities of the main influencing factors (soil texture, vegetation cover and climate factor were evaluated by fuzzy method and a combined wind erosion sensitivity map was compiled. The climate factor, as the driving factor of the changes, was assessed based on observed data for the reference period, while REMO and ALADIN regional climate model simulation data for the future periods. The changes in wind erosion sensitivity were evaluated on potentially affected agricultural land use types, and hot spot areas were allocated. Based on the results, 5–6% of the total agricultural areas were high sensitive areas in the reference period. In the 21st century slight or moderate changes of wind erosion sensitivity can be expected, and mostly ‘pastures’, ‘complex cultivation patterns’, and ‘land principally occupied by agriculture with significant areas of natural vegetation’ are affected. The applied combination of multi-indicator approach and fuzzy analysis provides novelty in the field of land sensitivity assessment. The method is suitable for regional scale analysis of wind erosion sensitivity changes and supports regional planning by allocating priority areas where changes in agro-technics or land use have to be considered.

  15. Assessment of future scenarios for wind erosion sensitivity changes based on ALADIN and REMO regional climate model simulation data

    Science.gov (United States)

    Mezősi, Gábor; Blanka, Viktória; Bata, Teodóra; Ladányi, Zsuzsanna; Kemény, Gábor; Meyer, Burghard C.

    2016-07-01

    The changes in rate and pattern of wind erosion sensitivity due to climate change were investigated for 2021-2050 and 2071-2100 compared to the reference period (1961-1990) in Hungary. The sensitivities of the main influencing factors (soil texture, vegetation cover and climate factor) were evaluated by fuzzy method and a combined wind erosion sensitivity map was compiled. The climate factor, as the driving factor of the changes, was assessed based on observed data for the reference period, while REMO and ALADIN regional climate model simulation data for the future periods. The changes in wind erosion sensitivity were evaluated on potentially affected agricultural land use types, and hot spot areas were allocated. Based on the results, 5-6% of the total agricultural areas were high sensitive areas in the reference period. In the 21st century slight or moderate changes of wind erosion sensitivity can be expected, and mostly `pastures', `complex cultivation patterns', and `land principally occupied by agriculture with significant areas of natural vegetation' are affected. The applied combination of multi-indicator approach and fuzzy analysis provides novelty in the field of land sensitivity assessment. The method is suitable for regional scale analysis of wind erosion sensitivity changes and supports regional planning by allocating priority areas where changes in agro-technics or land use have to be considered.

  16. Simulation of polar stratospheric clouds in the chemistry-climate-model EMAC via the submodel PSC

    Directory of Open Access Journals (Sweden)

    O. Kirner

    2011-03-01

    Full Text Available The submodel PSC of the ECHAM5/MESSy Atmospheric Chemistry model (EMAC has been developed to simulate the main types of polar stratospheric clouds (PSC. The parameterisation of the supercooled ternary solutions (STS, type 1b PSC in the submodel is based on Carslaw et al. (1995b, the thermodynamic approach to simulate ice particles (type 2 PSC on Marti and Mauersberger (1993. For the formation of nitric acid trihydrate (NAT particles (type 1a PSC two different parameterisations exist. The first is based on an instantaneous thermodynamic approach from Hanson and Mauersberger (1988, the second is new implemented and considers the growth of the NAT particles with the aid of a surface growth factor based on Carslaw et al. (2002. It is possible to choose one of this NAT parameterisation in the submodel. This publication explains the background of the submodel PSC and the use of the submodel with the goal of simulating realistic PSC in EMAC.

  17. Do regional climate models represent regional climate?

    Science.gov (United States)

    Maraun, Douglas; Widmann, Martin

    2014-05-01

    When using climate change scenarios - either from global climate models or further downscaled - to assess localised real world impacts, one has to ensure that the local simulation indeed correctly represents the real world local climate. Representativeness has so far mainly been discussed as a scale issue: simulated meteorological variables in general represent grid box averages, whereas real weather is often expressed by means of point values. As a result, in particular simulated extreme values are not directly comparable with observed local extreme values. Here we argue that the issue of representativeness is more general. To illustrate this point, assume the following situations: first, the (GCM or RCM) simulated large scale weather, e.g., the mid-latitude storm track, might be systematically distorted compared to observed weather. If such a distortion at the synoptic scale is strong, the simulated local climate might be completely different from the observed. Second, the orography even of high resolution RCMs is only a coarse model of true orography. In particular in mountain ranges the simulated mesoscale flow might therefore considerably deviate from the observed flow, leading to systematically displaced local weather. In both cases, the simulated local climate does not represent observed local climate. Thus, representativeness also encompasses representing a particular location. We propose to measure this aspect of representativeness for RCMs driven with perfect boundary conditions as the correlation between observations and simulations at the inter-annual scale. In doing so, random variability generated by the RCMs is largely averaged out. As an example, we assess how well KNMIs RACMO2 RCM at 25km horizontal resolution represents winter precipitation in the gridded E-OBS data set over the European domain. At a chosen grid box, RCM precipitation might not be representative of observed precipitation, in particular in the rain shadow of major moutain ranges

  18. The Monash University Interactive Simple Climate Model

    Science.gov (United States)

    Dommenget, D.

    2013-12-01

    The Monash university interactive simple climate model is a web-based interface that allows students and the general public to explore the physical simulation of the climate system with a real global climate model. It is based on the Globally Resolved Energy Balance (GREB) model, which is a climate model published by Dommenget and Floeter [2011] in the international peer review science journal Climate Dynamics. The model simulates most of the main physical processes in the climate system in a very simplistic way and therefore allows very fast and simple climate model simulations on a normal PC computer. Despite its simplicity the model simulates the climate response to external forcings, such as doubling of the CO2 concentrations very realistically (similar to state of the art climate models). The Monash simple climate model web-interface allows you to study the results of more than a 2000 different model experiments in an interactive way and it allows you to study a number of tutorials on the interactions of physical processes in the climate system and solve some puzzles. By switching OFF/ON physical processes you can deconstruct the climate and learn how all the different processes interact to generate the observed climate and how the processes interact to generate the IPCC predicted climate change for anthropogenic CO2 increase. The presentation will illustrate how this web-base tool works and what are the possibilities in teaching students with this tool are.

  19. Multi-year simulation of the East Asian Monsoon and Precipitation in China using a Regional Climate Model and Evaluation

    Institute of Scientific and Technical Information of China (English)

    LI Qiaoping; DING Yihui

    2005-01-01

    By using the regional climate model (RegCM_NCC), East Asian monsoon and precipitation over China during 1998 to 2002 are simulated. Results show that the model can well reproduce the seasonal patterns of mean circulation as well as the intensity and seasonal march of the East Asian monsoon. The simulated onset or retreat time of the West Pacific subtropical high, and the intensity and location of the South Asian high are consistent with the fact. The spatial distribution and transport of moisture in lower layer are also well simulated. The seasonal variations of regional rainfall and temperature are reproduced in the model, with three northward shift time and intensity of the rain belts over the sub-regions (such as Mid-Lower Yangtze basins and South China) well corresponding to the observation. However, the simulated summer monsoon is stronger compared with NCEP reanalysis fields, with the location of subtropical high being further north by 2-3 degrees than normal. Error evaluation shows that there is a discernible systematic bias in the simulated mean circulation pattern, with air temperature bias being positive over the land and negative over the ocean in the lower troposphere in summer. The systematic bias exaggerates the summer temperature difference between the land and ocean, which may be a main responsible factor for the stronger simulated summer monsoon, thus resulting in the overestimated rainfall in North China and it can not reflect well the abnormal rainfall distribution in these 5 years. The deficiency may be mainly contributed to the complex topography and cloud-radiation parameterization scheme. The analyses also indicate that it is difficult to simulate the persistent abnormal precipitation pattern over China. It is necessary to improve the model's capability further.

  20. Serious Simulation Role-Playing Games for Transformative Climate Change Education: "World Climate" and "Future Climate"

    Science.gov (United States)

    Rooney-Varga, J. N.; Sterman, J.; Sawin, E.; Jones, A.; Merhi, H.; Hunt, C.

    2012-12-01

    Climate change, its mitigation, and adaption to its impacts are among the greatest challenges of our times. Despite the importance of societal decisions in determining climate change outcomes, flawed mental models about climate change remain widespread, are often deeply entrenched, and present significant barriers to understanding and decision-making around climate change. Here, we describe two simulation role-playing games that combine active, affective, and analytical learning to enable shifts of deeply held conceptions about climate change. The games, World Climate and Future Climate, use a state-of-the-art decision support simulation, C-ROADS (Climate Rapid Overview and Decision Support) to provide users with immediate feedback on the outcomes of their mitigation strategies at the national level, including global greenhouse gas (GHG) emissions and concentrations, mean temperature changes, sea level rise, and ocean acidification. C-ROADS outcomes are consistent with the atmosphere-ocean general circulation models (AOGCMS), such as those used by the IPCC, but runs in less than one second on ordinary laptops, providing immediate feedback to participants on the consequences of their proposed policies. Both World Climate and Future Climate role-playing games provide immersive, situated learning experiences that motivate active engagement with climate science and policy. In World Climate, participants play the role of United Nations climate treaty negotiators. Participant emissions reductions proposals are continually assessed through interactive exploration of the best available science through C-ROADS. Future Climate focuses on time delays in the climate and energy systems. Participants play the roles of three generations: today's policymakers, today's youth, and 'just born.' The game unfolds in three rounds 25 simulated years apart. In the first round, only today's policymakers make decisions; In the next round, the young become the policymakers and inherit the

  1. How well do climate models simulate atmospheric teleconnctions over the North Pacific and East Asia associated with ENSO?

    Science.gov (United States)

    Kim, Sunyong; Son, Hye-Young; Kug, Jong-Seong

    2017-02-01

    During the El Niño and La Niña mature phase, atmospheric teleconnections over the North Pacific and East Asia vary considerably on sub-seasonal time scales, and are strongly phase-locked to the sub-seasonal evolution. In this study, we investigate how well climate models that participated in the Coupled Model Intercomparison Project Phase 5 (CMIP5) simulate the sub-seasonal evolution of teleconnections over the North Pacific and East Asia associated with El Niño-Southern Oscillation (ENSO). In the observations, there is a prominent anticyclone anomaly over the Kuroshio extension region (i.e. Kuroshio anticyclone), which significantly affects East Asian climate in the early winter (November-December) of El Niño years. However, in January, the Kuroshio anticyclone suddenly disappears, and a cyclonic flow dominates over the North Pacific. It is found here that the CMIP5 models simulate the overall extratropical teleconnection patterns, but they fail to reproduce some of these sub-seasonally-varying features in atmospheric circulation. For example, the models tend to simulate a weaker Kuroshio anticyclone in the early winter during El Niño phases, and fail to capture the abrupt decay of the Kuroshio anticyclone in the late winter. We demonstrate here that these systematic errors in ENSO teleconnection can be explained by systematic errors in tropical precipitation associated with ENSO. That is, negative precipitation anomalies over the western North Pacific (WNP) are too weak in the models compared to that in the observations, and their amplitude tends to be strengthened from December to the following January, while they are weakened in the observations. In addition, analyses on the inter-model diversity strongly support that relative magnitudes of WNP and central Pacific precipitation anomalies are critical for determining sub-seasonal evolution of ENSO teleconnections over the North Pacific and East Asia.

  2. Assessment of Potential Yield andClimate Change Sensitivity of Peanut Crop in Cagayan Valley, Philippines using DSSAT Simulation Model

    Science.gov (United States)

    Balderama, O. F.

    2013-12-01

    Peanut is a major upland crop in Cagayan Valley and a leguminous crop that requires less water and therefore, considered an important crop in improving productivity of upland and rainfed areas. However, little information is available on the potential productivity of the crop and analysis on the production constraints including climate change sensitivity. This study was aimed to determine yield potential and production constraints of peanut crop in Cagayan Valley through the use of Decision Support System for Agrotechnology Transfer (DSSAT) simulation modeling; analyze yield gaps between simulated and actual yield levels and to provide decision support to further optimize peanut production under climate change condition. Site of experiment for model calibration and validation was located on-station at Isabela State University, Echague, Isabela. Rainfall and other climatic variables were monitored using a HOBO weather station (Automatic Weather Station) which is strategically installed inside experimental zone.The inputs required to run the CSM model include information on soil and weather conditions, crop management practices and cultivar specific genetic coefficients. In the first step,a model calibration was conducted to determine the cultivar coefficients for certain peanut cultivar that are normally grown in Cagayan Valley. Crop growth and yield simulation modeling was undertaken using the Decision Support System for Agro-Technology Transfer (DSSAT) for small seeded peanut (Pn9). An evaluation of the CSM-CROPGRO-peanut model was performed with data sets from peanut experiment conducted from December 2011 to April 2012. The model was evaluated in the estimation of potential yield of peanut under rainfed condition and low-nitrogen application. Yield potential for peanut limited only by temperature and solar radiation and no-water and nutrient stress, ranged from 3274 to 4805 kg per hectare for six planting dates (October 1, October 15, November 1, November 15

  3. Do Coupled Climate Models Correctly SImulate the Upward Branch of the Deept Ocean Global Conveyor?

    Energy Technology Data Exchange (ETDEWEB)

    Sarmiento, Jorge L; Downes, Stephanie; Bianchi, Daniele

    2013-01-17

    The large-scale meridional overturning circulation (MOC) connects the deep ocean, a major reservoir of carbon, to the other components of the climate system and must therefore be accurately represented in Earth System Models. Our project aims to address the specific question of the pathways and mechanisms controlling the upwelling branch of the MOC, a subject of significant disagreement between models and observational syntheses, and among general circulation models. Observations of these pathways are limited, particularly in regions of complex hydrography such as the Southern Ocean. As such, we rely on models to examine theories of the overturning circulation, both physically and biogeochemically. This grant focused on a particular aspect of the meridional overturning circulation (MOC) where there is currently significant disagreement between models and observationally based analyses of the MOC, and amongst general circulation models. In particular, the research focused on addressing the following questions: 1. Where does the deep water that sinks in the polar regions rise to the surface? 2. What processes are responsible for this rise? 3. Do state-of-the-art coupled GCMs capture these processes? Our research had three key components: observational synthesis, model development and model analysis. In this final report we outline the key results from these areas of research for the 2007 to 2012 grant period. The research described here was carried out primarily by graduate student, Daniele Bianchi (now a Postdoc at McGill University, Canada), and Postdoc Stephanie Downes (now a Research Fellow at The Australian national University, Australia). Additional support was provided for programmers Jennifer Simeon as well as Rick Slater.

  4. Simulation of the spatiotemporal variability of the World Ocean sea surface hight by the INM climate models

    Science.gov (United States)

    Iakovlev, N. G.; Volodin, E. M.; Gritsun, A. S.

    2016-07-01

    The results of simulations of the World Ocean sea surface hight (SSH) in by various versions of the Climate Model of the Institute of Numerical Mathematics, Russian Academy of Sciences, are compared with the CNES-CLS09 fields of the mean dynamic topography (deviation of the ocean level from the geoid). Three models with different ocean blocks are considered which slightly differ in numerical schemes and have various horizontal spatial resolution, i.e., the INMCM4 model, which participated in the Climate Model Intercomparison Project (CMIP Phase 5, resolution of 1° × 1/2°); the INMCM5 model, which participates in the next project, CMIP6 (resolution of 1/2° × 1/4°); and the advanced INMCM-ER eddy-resolving model (resolution of 1/6° × 1/8°). It is shown that an increase in the spatial resolution improves the reproduction of ocean currents (with Agulhas and Kuroshio currents as examples) and their variability. A probable cause of relatively high errors in the reproduction of the SSH of Southern and Indian oceans is discussed.

  5. Future water availability in North African dams simulated by high-resolution regional climate models

    Science.gov (United States)

    Tramblay, Yves; Jarlan, Lionel; Hanich, Lahoucine; Somot, Samuel

    2016-04-01

    In North Africa, the countries of Morocco, Algeria and Tunisia are already experiencing water scarcity and a strong interannual variability of precipitation. To better manage their existing water resources, several dams and reservoirs have been built on most large river catchments. The objective of this study is to provide quantitative scenarios of future changes in water availability for the 47 major dams and reservoirs catchments located in North Africa. An ensemble of regional climate models (RCM) with a spatial resolution of 12km, driven by different general circulation models (GCM), from the EuroCORDEX experiment have been considered to analyze the projected changes on temperature, precipitation and potential evapotranspiration (PET) for two scenarios (RCP4.5 and RCP8.5) and two time horizons (2040-2065 and 2065-2090). PET is estimated from RCM outputs either with the FAO-Penman-Monteith (PM) equation, requiring air temperature, relative humidity, net radiation and wind, or with the Hargreave Samani (HS) equation, requiring only air temperature. The water balance is analyzed by comparing the climatic demand and supply of water, considering that for most of these catchments groundwater storage is negligible over long time periods. Results indicated a future temperature increase for all catchments between +1.8° and +4.2°, depending on the emission scenario and the time period considered. Precipitation is projected to decrease between -14% to -27%, mainly in winter and spring, with a strong East to West gradient. PET computed from PM or HS formulas provided very similar estimates and projections, ranging between +7% to +18%. Changes in PET are mostly driven by rising temperatures and are greatest during dry summer months than for the wet winter season. Therefore the increased PET has a lower impact than declining precipitation on future water availability, which is expected to decrease by -19% to -33% on average.

  6. Assessment of high latitude variability and extreme events in the Bering Sea as simulated by a global climate model

    Science.gov (United States)

    Walston, Joshua M.

    Atmospheric and Oceanic observations of the Arctic and Subarctic are relatively sparse and hinder our ability to analyze short term variability and long-duration anomalies of physical and biological variables over decadal time scales. Earth System Models (ESM's), such as the Community Earth System Model (CESM1), represent a useful tool to advance the understanding and the predictive potential of large-scale shifts in the climate and climate related impacts. This thesis initially focuses on assessing the skill of the Community Climate System Model (CCSM4), to capture natural variability of the climate system. Subsequently, I examine the impacts of variability and seasonal-scale extremes of the physical environment on the marine ecosystem of the eastern Bering Sea as simulated by an earth system model, the CESM1, which includes the CCSM4 and earth system elements. A performance assessment of key atmospheric components (air temperature, sea level pressure, wind speed and direction) simulated by the CCSM4 over the Bering Sea and Arctic domains suggests a general improvement in model predictions at high latitudes relative to the model's predecessor, the CCSM3. However, several shortcomings, with possible implications for marine ecosystem modeling, still remain in this version of the CCSM. The most important of which includes an under-simulated Siberian High and a large northwest displacement of the Aleutian Low resulting in a negative bias of up to 8 hPa over the Bering Sea. The simulated inter-annual variability of surface air temperature and sea level pressure over the Bering Sea was found to exceed observed variability by ˜1.5 to 2 times. The displaced pressure systems and increased variability could have important ramifications for modeling efforts that use CCSM atmospheric output as drivers for marine ecosystem studies. When the CCSM was combined with other earth system elements to form the CESM, the coupled model was found to simulate strong linear relationships

  7. Evaluation of the present climate simulated by the regional Eta model driven by the Brazilian Global coupled ocean-atmosphere Model

    Science.gov (United States)

    Chou, Sin Chan; Lyra, André; Juliano Silva, Adan; Nobre, Paulo

    2013-04-01

    The Eta Model is used operationally by INPE at the Centre for Weather Forecasts and Climate Studies (CPTEC) to produce weather forecasts over South America since 1997 and seasonal climate forecasts since 2002. The model has gone through upgrades along these years and is able to produce decadal integrations to downscale climate projections. Likewise, the INPE global atmospheric model has been coupled to MOM4 ocean model and decadal integrations in the period 1960-2105 was produced and contributed to the CMIP5 dataset. The development of the Brazilian Earth System Model (BESM) has been ongoing parallel to the development of the Brazilian regional earth system model (BESM-R). The objective of this work is to evaluate the regional Eta model nested in the BESM in the present climate simulations, from 1961-1990. The Eta model was configured with 20-km horizontal resolution and 38 layers, in a domain covering all South America. In the lower boundary, sea surface temperature was provided by the BESM and was updated daily during the regional integration, whereas the lateral boundaries were updated every 6 hours with the BESM atmospheric conditions. Continuous 30-year integrations were carried out by the regional model. Large scale circulation pattern at upper and low levels are shown in comparison with the respective BESM flow and evaluated against reanalyses. The regional model shows improvement in the precipitation and temperature pattern over the continent. Seasonal cycle of precipitation and temperature are also shown.

  8. Multi-model ensemble simulation and projection in the climate change in the Mekong River Basin. Part I: temperature.

    Science.gov (United States)

    Huang, Yong; Wang, Fengyou; Li, Yi; Cai, Tijiu

    2014-11-01

    This paper evaluates the performance of the Coupled Model Intercomparison Project phase 5 (CMIP5) in simulating annual and decadal temperature in the Mekong River Basin from 1950 to 2005. By use of Bayesian multi-model averaging method, the future projection of temperature variation under different scenarios are also analyzed. The results show, the performances of climate model are more accurate in space than time, the model can catch the warming characteristics in the Mekong river Basin, but the accuracy of simulation is not good enough. Bayesian multi-model averaging method can improve the annual and decadal temperature simulation when compared to a single result. The projected temperature in Mekong River will increase by 0.88 °C/100 year, 2.15 °C/100 year and 4.96 °C/100 year for the RCP2.6, RCP4.5, and RCP8.5 scenarios, respectively, over the twenty-first century. The findings will be beneficial for local people and policy-maker to formulate regional strategies against the potential menaces of warming scenarios.

  9. Simulations of the Tropical Intraseasonal Oscillation by the Atmospheric General Circulation Model of the Beijing Climate Center

    Institute of Scientific and Technical Information of China (English)

    DONG Min; WU Tongwen; WANG Zaizhi; ZHANG Fang

    2010-01-01

    The performance of BCC (Beijing Climate Center) AGCM 2.0.1 (Atmospheric General Circulation Model version 2.0.1) in simulating the tropical intraseasonal oscillation (TIO) is examined in this paper.The simulations are validated against observation and compared with the NCAR CAM3 (Community Atmosphere Model version 3) results.The BCC AGCM2.0.1 is developed based on the original BCC AGCM (version 1) and NCAR CAM3.New reference atmosphere and reference pressure are introduced into the model.Therefore,the original prognostic variables of temperature and surface pressure become their departures from the reference atmosphere.A new Zhang-McFarlane convective parameterization scheme is incorporated into the model with a few modifications.Other modifications include those in the boundary layer process and snow cover calculation.All simulations are run for 52 yr from 1949 to 2001 under the lower boundary conditions of observed monthly SST.The TIOs from the model are analyzed.The comparison shows that the NCAR CAM3 has a poor ability in simulating the TIO.The simulated strength of the TIO is very weak.The energy of the eastward moving waves is similar to that of the westward moving waves in CAM3.While in observation the former is much larger than the latter.The seasonal variation and spatial distribution of the TIO produced by CAM3 are also much different from the observation.The ability of the BCC AGCM2.0.1 in simulating the TIO is significantly better.The simulated TIO is evident.The strength of the TIO produced by the BCC AGCM2.0.1 is close to the observation.The energy of eastward moving.waves is much stronger than that of the westward moving waves,which is consistent with the observation.There is no significant difference in the seasonal variation and spatial distribution of the TIO between the BCC model simulation and the observation.In general,the BCC model performs better than CAM3 in simulating the TIO.

  10. An evaluation of Arctic cloud and radiation processes during the SHEBA year: simulation results from eight Arctic regional climate models

    Energy Technology Data Exchange (ETDEWEB)

    Wyser, K.; Willen, U. [Rossby Centre, SMHI, Norrkoeping (Sweden); Jones, C.G.; Du, P.; Girard, E.; Laprise, R. [Universite du Quebec a Montreal, Canadian Regional Climate Modelling and Diagnostics Network, Montreal (Canada); Cassano, J.; Serreze, M.; Shaw, M.J. [University of Colorado, Cooperative Institute for Research in Environmental Sciences and Department of Atmospheric and Oceanic Sciences, Boulder, CO (United States); Christensen, J.H. [Danish Meteorological Institute, Copenhagen (Denmark); Curry, J.A. [School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA (United States); Dethloff, K.; Rinke, A. [Alfred Wegener Institute for Polar and Marine Research, Research Unit, Potsdam (Germany); Haugen, J.-E.; Koeltzow, M. [Norwegian Meteorological Institute, Oslo (Norway); Jacob, D.; Pfeifer, S. [Max Planck Institute for Meteorology, Hamburg (Germany); Lynch, A. [Monash University, School of Geography and Environmental Science, Melbourne (Australia); Tjernstroem, M.; Zagar, M. [Stockholm University, Department of Meteorology, Stockholm (Sweden)

    2008-02-15

    Eight atmospheric regional climate models (RCMs) were run for the period September 1997 to October 1998 over the western Arctic Ocean. This period was coincident with the observational campaign of the Surface Heat Budget of the Arctic Ocean (SHEBA) project. The RCMs shared common domains, centred on the SHEBA observation camp, along with a common model horizontal resolution, but differed in their vertical structure and physical parameterizations. All RCMs used the same lateral and surface boundary conditions. Surface downwelling solar and terrestrial radiation, surface albedo, vertically integrated water vapour, liquid water path and cloud cover from each model are evaluated against the SHEBA observation data. Downwelling surface radiation, vertically integrated water vapour and liquid water path are reasonably well simulated at monthly and daily timescales in the model ensemble mean, but with considerable differences among individual models. Simulated surface albedos are relatively accurate in the winter season, but become increasingly inaccurate and variable in the melt season, thereby compromising the net surface radiation budget. Simulated cloud cover is more or less uncorrelated with observed values at the daily timescale. Even for monthly averages, many models do not reproduce the annual cycle correctly. The inter-model spread of simulated cloud-cover is very large, with no model appearing systematically superior. Analysis of the co-variability of terms controlling the surface radiation budget reveal some of the key processes requiring improved treatment in Arctic RCMs. Improvements in the parameterization of cloud amounts and surface albedo are most urgently needed to improve the overall performance of RCMs in the Arctic. (orig.)

  11. Climate Variability-Observations, Reconstructions, and Model Simulations for the Atlantic-European and Alpine Region from 1500-2100 AD

    Energy Technology Data Exchange (ETDEWEB)

    Raible, Christoph C. [Climate and Environmental Physics, Physics Institute, University of Bern, Sidlerstrasse 5, CH-3012 Bern (Switzerland); Casty, C.; Luterbacher, J.; Pauling, A.; Wanner, H. [Institute of Geography, University of Bern, Hallerstrasse 12, CH-3012 Bern (Switzerland); Esper, J.; Frank, D.C.; Buentgen, U. [Swiss Federal Research Institute WSL, Zuercherstrasse 111, CH-8903 Birmensdorf (Switzerland); Roesch, A.C.; Tschuck, P.; Wild, M.; Vidale, P.L.; Schaer, C. [Institute for Atmospheric and Climate Science ETH, Winterthurerstrasse 190, CH-8057 Zuerich (Switzerland)

    2006-11-15

    A detailed analysis is undertaken of the Atlantic-European climate using data from 500-year-long proxy-based climate reconstructions, a long climate simulation with perpetual 1990 forcing, as well as two global and one regional climate change scenarios. The observed and simulated interannual variability and teleconnectivity are compared and interpreted in order to improve the understanding of natural climate variability on interannual to decadal time scales for the late Holocene. The focus is set on the Atlantic-European and Alpine regions during the winter and summer seasons, using temperature, precipitation, and 500 hPa geopotential height fields. The climate reconstruction shows pronounced interdecadal variations that appear to 'lock' the atmospheric circulation in quasi-steady long-term patterns over multi-decadal periods controlling at least part of the temperature and precipitation variability. Different circulation patterns are persistent over several decades for the period 1500 to 1900. The 500-year-long simulation with perpetual 1990 forcing shows some substantial differences, with a more unsteady teleconnectivity behaviour. Two global scenario simulations indicate a transition towards more stable teleconnectivity for the next 100 years. Time series of reconstructed and simulated temperature and precipitation over the Alpine region show comparatively small changes in interannual variability within the time frame considered, with the exception of the summer season, where a substantial increase in interannual variability is simulated by regional climate models.

  12. Comparison of Hydrological Impacts of Climate Change Simulated by WASMOD and HBV Models in Different Climatic Zones China, Ethiopia, and Norway

    OpenAIRE

    Eregno, Fasil Ejigu

    2009-01-01

    Abstract Recent advances in hydrological impact studies points that the response of specific catchments to climate change scenario using a single model approach is questionable. Based on this hypothesis, this study was aimed at investigating the impact of climate change on the hydrological regime of river basins in three different climatic zones (China, Ethiopia and Norway) using WASMOD and HBV hydrological models. Specifically the objectives include (i) examining and comparing the hydrolo...

  13. Climate change, forest management and nitrogen deposition influence on carbon sequestration in forest ecosystems in Russia: simulation modelling approach

    Science.gov (United States)

    Komarov, Alexander; Kudeyarov, Valery; Shanin, Vladimir

    2014-05-01

    Russian land ecosystems occupy more than 1/9th global land area. Therefore its carbon budget is an essential contribution to the global carbon budget. The first rough estimate of carbon balance on Russian territory was made on comparison data on total soil respiration (Kudeyarov et. al., 1995) and NPP calculated on data on biological productivity of different ecosystems over Russia. The carbon balance was evaluated as a C-sink. Further estimates of Russian C budget by V.Kudeyarov et al., (2007) and I.Kurganova et al., (2010) were more correct and included soil microbial flux, and non-respiratory processes: fossil fuel, agriculture, forest fires and post-fire emissions, insect damage, etc. According to estimates the total C-sink of Russian territory for early nineties was about -0.8-1.0 Pg C per year. The later IIASA account developed by A.Shvidenko et al. (2010) has provided current estimates of C fluxes and storages in Russia and showed that its terrestrial ecosystems served as a net carbon sink of -0.5-0.7 PgC yr-1 during the last decade. Taking into account big uncertainties of determination of carbon balance constituents one can say that results by IIASA and our Institute are rather close. Resulting effect of two processes (sequestration and CO2 emission) can be analysed by mathematical modelling only. Corresponding system of models of organic matter dynamics in forest ecosystems EFIMOD was developed in our Institute last decade and applied in Russia and other countries for evaluation of impacts of climate changes, forest management and forest fires. The comparative simulations of carbon and nitrogen dynamics in the mixed forest ecosystems of Central Russia from different climatic zones and site conditions have been made. Three large forest areas with the total square of about 17,000 km2 distinct in environmental conditions were chosen. We used the data of the forest inventory for model initialization. Four simulation scenarios (without disturbances, with

  14. Impacts of using spectral nudging on regional climate model RCA4 simulations of the Arctic

    Directory of Open Access Journals (Sweden)

    P. Berg

    2013-01-01

    Full Text Available The performance of the Rossby Centre regional climate model RCA4 is investigated for the Arctic CORDEX region, with an emphasis on its suitability to be coupled to a regional ocean and sea-ice model. Large biases in mean sea level pressure (MSLP are identified, with pronounced too high pressure centred over the North Pole in summer of over 5 hPa, and too low pressure in winter of a similar magnitude. These lead to biases in the surface winds, which will potentially lead to strong sea-ice biases in a future coupled system. The large scale circulation is believed to be the major reason for the biases, and an implementation of spectral nudging is applied to remedy the problems by constraining the large scale components of the driving fields within the interior domain. It is found that the spectral nudging generally corrects for the MSLP and wind biases, while not significantly affecting other variables such as surface radiative components, two metre temperature and precipitation.

  15. Coupling of regional atmospheric-ocean models for climate applications in the Mediterranean basin by using CORDEX-compliant simulations

    Science.gov (United States)

    Jimenez-Guerrero, Pedro; Montávez, Juan P.; Lorente-Plazas, Raquel

    2013-04-01

    Nowadays, most regional climate models (RCMs) are essentially composed of an atmospheric component coupled to a land surface scheme and driven over ocean areas by prescribed sea surface temperature (SST). Although such a RCM can be sufficient for many applications, there are cases (like in the Mediterranean basin) in which fine scale feedbacks associated with air-sea interactions can substantially influence the spatial and temporal structure of regional climates. Therefore, in this work we present the first testing phase of the application of a coupled atmospheric-ocean regional climate model (AORCM) for the Mediterranean basin under the framework of the CORWES project. CORWES is a Spanish consortium of research groups using the Weather Research and Forecasting (WRF) model to contribute to the Coordinated Regional Climate Downscaling Experiment (CORDEX). We use WRF and ROMS models as the atmospheric and oceanic component, respectively. Coupling between WRF and ROMS is achieved in the following way: on a prescribed interval of 2 h, WRF sends wind stress, surface heat and water fluxes to ROMS time-averaged over the previous two hours. One hour later, and also with a prescribed interval of 2 h, ROMS sends time-averaged SST to WRF. Here, we mainly focus on the performance of the coupled system in reproducing the ocean surface temperatures. To separate effects of the coupling on SST, additional uncoupled atmospheric simulations are also done in parallel. The case study covers the years 2001-2005 and is described below. The resolution of the domain used is 12 km. The number of vertical levels is 30 for WRF. The ROMS domain, with 32 vertical levels, is slightly smaller than WRF innermost nest and has a higher resolution of 4 km. The lateral atmospheric boundary conditions for WRF are taken from ERA-Interim reanalysis. The lateral oceanic boundary conditions for ROMS come from the downscaling of the Simple Ocean Data Assimilation analysis (SODA) by an uncoupled nested ROMS

  16. Simulation of polar stratospheric clouds in the chemistry-climate-model EMAC via the submodel PSC

    Directory of Open Access Journals (Sweden)

    O. Kirner

    2010-11-01

    Full Text Available The submodel PSC of the ECHAM5/MESSy Atmospheric Chemistry model (EMAC has been developed to simulate the main types of polar stratospheric clouds (PSC. The parameterisation of the supercooled ternary solutions (STS, type 1b PSC in the submodel is based on Carslaw et al. (1995b, the thermodynamical approach to simulate ice particles (type 2 PSC on Marti and Mauersberger (1993. For the formation of nitric acid trihydrate (NAT particles (type 1a PSC two different parameterisations exist. The first one is based on an instantaneous thermodynamical approach from Hanson and Mauersberger (1988, the second one (new implemented by Kirner, 2008 considers the growth of the NAT particles with aid of a surface growth factor based on Carslaw et al. (2002. Via namelist switches the NAT parameterisation, as well as some parameters for the NAT and ice formation can be chosen. This publication explains the background of the submodel PSC and the use of the submodel with the goal to simulate realistic PSC in EMAC.

  17. The impact of land-cover modification on the June meteorology of China since 1700, simulated using a regional climate model

    NARCIS (Netherlands)

    Wang, H.; Pitman, A.J.; Zhao, M.; Leemans, R.

    2003-01-01

    A series of simulations was conducted using a regional climate model with a domain covering mainland China. Simulations were conducted for a single June using estimated land cover for 1700, 1750, 1800, 1850, 1900, 1950, 1970 and 1990. The conversion of land cover between these periods was extensive

  18. NASA Center for Climate Simulation (NCCS) Presentation

    Science.gov (United States)

    Webster, William P.

    2012-01-01

    The NASA Center for Climate Simulation (NCCS) offers integrated supercomputing, visualization, and data interaction technologies to enhance NASA's weather and climate prediction capabilities. It serves hundreds of users at NASA Goddard Space Flight Center, as well as other NASA centers, laboratories, and universities across the US. Over the past year, NCCS has continued expanding its data-centric computing environment to meet the increasingly data-intensive challenges of climate science. We doubled our Discover supercomputer's peak performance to more than 800 teraflops by adding 7,680 Intel Xeon Sandy Bridge processor-cores and most recently 240 Intel Xeon Phi Many Integrated Core (MIG) co-processors. A supercomputing-class analysis system named Dali gives users rapid access to their data on Discover and high-performance software including the Ultra-scale Visualization Climate Data Analysis Tools (UV-CDAT), with interfaces from user desktops and a 17- by 6-foot visualization wall. NCCS also is exploring highly efficient climate data services and management with a new MapReduce/Hadoop cluster while augmenting its data distribution to the science community. Using NCCS resources, NASA completed its modeling contributions to the Intergovernmental Panel on Climate Change (IPCG) Fifth Assessment Report this summer as part of the ongoing Coupled Modellntercomparison Project Phase 5 (CMIP5). Ensembles of simulations run on Discover reached back to the year 1000 to test model accuracy and projected climate change through the year 2300 based on four different scenarios of greenhouse gases, aerosols, and land use. The data resulting from several thousand IPCC/CMIP5 simulations, as well as a variety of other simulation, reanalysis, and observationdatasets, are available to scientists and decision makers through an enhanced NCCS Earth System Grid Federation Gateway. Worldwide downloads have totaled over 110 terabytes of data.

  19. Application of all-relevant feature selection for the failure analysis of parameter-induced simulation crashes in climate models

    Science.gov (United States)

    Paja, Wiesław; Wrzesien, Mariusz; Niemiec, Rafał; Rudnicki, Witold R.

    2016-03-01

    Climate models are extremely complex pieces of software. They reflect the best knowledge on the physical components of the climate; nevertheless, they contain several parameters, which are too weakly constrained by observations, and can potentially lead to a simulation crashing. Recently a study by Lucas et al. (2013) has shown that machine learning methods can be used for predicting which combinations of parameters can lead to the simulation crashing and hence which processes described by these parameters need refined analyses. In the current study we reanalyse the data set used in this research using different methodology. We confirm the main conclusion of the original study concerning the suitability of machine learning for the prediction of crashes. We show that only three of the eight parameters indicated in the original study as relevant for prediction of the crash are indeed strongly relevant, three others are relevant but redundant and two are not relevant at all. We also show that the variance due to the split of data between training and validation sets has a large influence both on the accuracy of predictions and on the relative importance of variables; hence only a cross-validated approach can deliver a robust prediction of performance and relevance of variables.

  20. SUNYA Regional Climate Model Simulations of East Asia Summer Monsoon: Effects of Cloud Vertical Structure on the Surface Energy Balance

    Directory of Open Access Journals (Sweden)

    Wei Gong and Wei-Chyung Wang

    2007-01-01

    Full Text Available We used the State University of New York at Albany (SUNYA regional climate model to study the effect of cloud vertical distribution in affecting the surface energy balance of the East Asia summer monsoon (EASM. Simulations were conducted for the summers of 1988 and 1989, during which large contrast in the intra-seasonal cloud radiative forcing (CRF was observed at the top of the atmosphere. The model results indicate that both the high and low clouds are persistent throughout the summer months in both years. Because of large cloud water, low clouds significantly reduce the solar radiation flux reaching the surface, which nevertheless still dominate the surface energy balance, accounting for more than 50% of the surface heating. The low clouds also contribute significantly the downward longwave radiation to the surface with values strongly dependent on the cloud base temperature. The presence of low clouds effectively decreases the temperature and moisture gradients near surface, resulting in a substantial decrease in the sensible and latent heat fluxes from surface, which partially compensate the decrease of the net radiative cooling of the surface. For example, in the two days, May 8 and July 11 of 1988, the total cloud cover of 80% is simulated, but the respective low cloud cover (water was 63% (114 gm-2 and 22% (21 gm-2. As a result, the downward solar radiation is smaller by 161 Wm-2 in May 8. On the other hand, the cloud temperature was _ lower, yielding 56 Wm-2 smaller downward longwave radiation. The near surface temperature and gradient is more than _ smaller (and moisture gradient, leading to 21 and 81 Wm-2 smaller sensible heat and latent heat fluxes. It is also demonstrated that the model is capable to reproduce the intraseasonal variation of shortwave CRF, and catches the relationship between total cloud cover and SW CRF. The model results show the dominance of high cloud on the regional mean longwave CRF and low cloud on the intra

  1. Vegetation-climate feedback causes reduced precipitation and tropical rainforest cover in CMIP5 regional Earth system model simulation over Africa

    Science.gov (United States)

    Wu, M.; Smith, B.; Samuelsson, P.; Rummukainen, M.; Schurgers, G.

    2012-12-01

    We applied a coupled regional climate-vegetation model, RCA-GUESS (Smith et al. 2011), over the CORDEX Africa domain, forced by boundary conditions from a CanESM2 CMIP5 simulation under the RCP8.5 future climate scenario. The simulations were from 1961 to 2100 and covered the African continent at a horizontal grid spacing of 0.44°. RCA-GUESS simulates changes in the phenology, productivity, relative cover and population structure of up to eight plant function types (PFTs) in response to forcing from the climate part of the model. These vegetation changes feed back to simulated climate through dynamic adjustments in surface energy fluxes and surface properties. Changes in the net ecosystem-atmosphere carbon flux and its components net primary production (NPP), heterotrophic respiration and emissions from biomass burning were also simulated but do not feed back to climate in our model. Constant land cover was assumed. We compared simulations with and without vegetation feedback switched "on" to assess the influence of vegetation-climate feedback on simulated climate, vegetation and ecosystem carbon cycling. Both positive and negative warming feedbacks were identified in different parts of Africa. In the Sahel savannah zone near 15°N, reduced vegetation cover and productivity, and mortality caused by a deterioration of soil water conditions led to a positive warming feedback mediated by decreased evapotranspiration and increased sensible heat flux between vegetation and the atmosphere. In the equatorial rainforest stronghold region of central Africa, a feedback syndrome characterised by reduced plant production and LAI, a dominance shift from tropical trees to grasses, reduced soil water and reduced rainfall was identified. The likely underlying mechanism was a decline in evaporative water recycling associated with sparser vegetation cover, reminiscent of Earth system model studies in which a similar feedback mechanism was simulated to force dieback of tropical

  2. The role of lateral boundary conditions in simulations of mineral aerosols by a regional climate model of Southwest Asia

    Energy Technology Data Exchange (ETDEWEB)

    Marcella, Marc Pace [Ralph M. Parsons Laboratory, Department of Civil and Environmental Engineering, Cambridge, MA (United States); Massachusetts Institute of Technology, Cambridge, Massachusetts (United States); Eltahir, Elfatih A.B. [Massachusetts Institute of Technology, Cambridge, Massachusetts (United States)

    2012-01-15

    The importance of specifying realistic lateral boundary conditions in the regional modeling of mineral aerosols has not been examined previously. This study examines the impact of assigning values for mineral aerosol (dust) concentrations at the lateral boundaries of Regional Climate Model version 3 (RegCM3) and its aerosol model over Southwest Asia. Currently, the dust emission module of RegCM3 operates over the interior of the domain, allowing dust to be transported to the boundaries, but neglecting any dust emitted at these points or from outside the domain. To account for possible dust occurring at, or entering from the boundaries, mixing ratios of dust concentrations from a larger domain RegCM3 simulation are specified at the boundaries of a smaller domain over Southwest Asia. The lateral boundary conditions are monthly averaged concentration values ({mu}g of dust per kg of dry air) resolved in the vertical for all four dust bin sizes within RegCM3's aerosol model. RegCM3 simulations with the aerosol/dust model including lateral boundary conditions for dust are performed for a five year period and compared to model simulations without prescribed dust concentrations at the boundaries. Results indicate that specifying boundary conditions has a significant impact on dust loading across the entire domain over Southwest Asia. More specifically, a nearly 30% increase in aerosol optical depth occurs during the summer months from specifying realistic dust boundary conditions, bringing model results closer to observations such as MISR. In addition, smaller dust particles at the boundaries have a more important impact than large particles in affecting the dust loading within the interior of this domain. Moreover, increases in aerosol optical depth and dust concentrations within the interior domain are not entirely caused by inflow from the boundaries; results indicate that an increase in the gradient of concentration at the boundaries causes an increase of

  3. Indicators of Arctic Sea Ice Bistability in Climate Model Simulations and Observations

    Science.gov (United States)

    2014-09-30

    1 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. Indicators of Arctic Sea Ice Bistability in Climate...possibility that the climate system supports multiple Arctic sea ice states that are relevant for the evolution of sea ice during the next several...the most relevant scalar quantities related to the hemisphere-scale Arctic sea ice cover that indicate the presence of bistability, as well as the

  4. Micro Climate Simulation in new Town 'Hashtgerd'

    Science.gov (United States)

    Sodoudi, S.; Langer, I.; Cubasch, U.

    2012-04-01

    One of the objectives of climatological part of project Young Cities 'Developing Energy-Efficient Urban Fabric in the Tehran-Karaj Region' is to simulate the micro climate (with 1m resolution) in 35ha of new town Hashtgerd, which is located 65 km far from mega city Tehran. The Project aims are developing, implementing and evaluating building and planning schemes and technologies which allow to plan and build sustainable, energy-efficient and climate sensible form mass housing settlements in arid and semi-arid regions ("energy-efficient fabric"). Climate sensitive form also means designing and planning for climate change and its related effects for Hashtgerd New Town. By configuration of buildings and open spaces according to solar radiation, wind and vegetation, climate sensitive urban form can create outdoor thermal comfort. To simulate the climate on small spatial scales, the micro climate model Envi-met has been used to simulate the micro climate in 35 ha. The Eulerian model ENVI-met is a micro-scale climate model which gives information about the influence of architecture and buildings as well as vegetation and green area on the micro climate up to 1 m resolution. Envi-met has been run with information from topography, downscaled climate data with neuro-fuzzy method, meteorological measurements, building height and different vegetation variants (low and high number of trees) Through the optimal Urban Design and Planning for the 35ha area the microclimate results shows, that with vegetation the microclimate in streets will be change: • 2 m temperature is decreased by about 2 K • relative humidity increase by about 10 % • soil temperature is decreased by about 3 K • wind speed is decreased by about 60% The style of buildings allows free movement of air, which is of high importance for fresh air supply. The increase of inbuilt areas in 35 ha reduces the heat island effect through cooling caused by vegetation and increase of air humidity which caused by

  5. Tropical-temperate interactions over southern Africa simulated by a regional climate model

    Energy Technology Data Exchange (ETDEWEB)

    Vigaud, N.; Pohl, B.; Cretat, J. [UMR 6282 Biogeosciences CNRS/Universite de Bourgogne, Centre de Recherches de Climatologie, Dijon (France)

    2012-12-15

    The Weather Research and Forecasting model (WRF) forced by ERA40 re-analyses, is used to examine, at regional scale, the role of key features of the local atmospheric circulation on the origin and development of Tropical Temperate Troughs (TTTs) representing a major contribution to South African rainfall during austral summer. A cluster analysis applied on 1971-2000 ERA40 and WRF simulated daily outgoing longwave radiation reveals for the November-February season three coherent regimes characteristic of TTTs over the region. Analyses of WRF simulated TTTs suggest that their occurrence is primarily linked with mid-latitude westerly waves and their phasing. Ensemble experiments designed for the case of austral summer 1996/1997 allow to examine the reproducibility of TTT events. The results obtained illustrate the importance of westerly waves phasing regarding the persistence of rain-producing continental TTT events. Moreover, oceanic surface conditions prevailing over the Agulhas current regions of the South West Indian Ocean (SWIO) are also found to influence TTT persistence for regional experiments with an oceanic mixed layer, warmer sea surface temperatures being associated with increased moisture advection from the SWIO where latent heat release is enhanced, favoring baroclinic instability and thus sustaining convection activity locally. (orig.)

  6. Quality assessment of atmospheric surface fields over the Baltic Sea from an ensemble of regional climate model simulations with respect to ocean dynamics

    Directory of Open Access Journals (Sweden)

    H. E. Markus Meier

    2011-05-01

    Full Text Available Climate model results for the Baltic Sea region from an ensemble of eight simulations using the Rossby Centre Atmosphere model version 3 (RCA3 driven with lateral boundary data from global climate models (GCMs are compared with results from a downscaled ERA40 simulation and gridded observations from 1980-2006. The results showed that data from RCA3 scenario simulations should not be used as forcing for Baltic Sea models in climate change impact studies because biases of the control climate significantly affect the simulated changes of future projections. For instance, biases of the sea ice cover in RCA3 in the present climate affect the sensitivity of the model's response to changing climate due to the ice-albedo feedback. From the large ensemble of available RCA3 scenario simulations two GCMs with good performance in downscaling experiments during the control period 1980-2006 were selected. In this study, only the quality of atmospheric surface fields over the Baltic Sea was chosen as a selection criterion. For the greenhouse gas emission scenario A1B two transient simulations for 1961-2100 driven by these two GCMs were performed using the regional, fully coupled atmosphere-ice-ocean model RCAO. It was shown that RCAO has the potential to improve the results in downscaling experiments driven by GCMs considerably, because sea surface temperatures and sea ice concentrations are calculated more realistically with RCAO than when RCA3 has been forced with surface boundary data from GCMs. For instance, the seasonal 2 m air temperature cycle is closer to observations in RCAO than in RCA3 downscaling simulations. However, the parameterizations of air-sea fluxes in RCAO need to be improved.

  7. Air traffic simulation in chemistry-climate model EMAC 2.41: AirTraf 1.0

    Science.gov (United States)

    Yamashita, Hiroshi; Grewe, Volker; Jöckel, Patrick; Linke, Florian; Schaefer, Martin; Sasaki, Daisuke

    2016-09-01

    Mobility is becoming more and more important to society and hence air transportation is expected to grow further over the next decades. Reducing anthropogenic climate impact from aviation emissions and building a climate-friendly air transportation system are required for a sustainable development of commercial aviation. A climate optimized routing, which avoids climate-sensitive regions by re-routing horizontally and vertically, is an important measure for climate impact reduction. The idea includes a number of different routing strategies (routing options) and shows a great potential for the reduction. To evaluate this, the impact of not only CO2 but also non-CO2 emissions must be considered. CO2 is a long-lived gas, while non-CO2 emissions are short-lived and are inhomogeneously distributed. This study introduces AirTraf (version 1.0) that performs global air traffic simulations, including effects of local weather conditions on the emissions. AirTraf was developed as a new submodel of the ECHAM5/MESSy Atmospheric Chemistry (EMAC) model. Air traffic information comprises Eurocontrol's Base of Aircraft Data (BADA Revision 3.9) and International Civil Aviation Organization (ICAO) engine performance data. Fuel use and emissions are calculated by the total energy model based on the BADA methodology and Deutsches Zentrum für Luft- und Raumfahrt (DLR) fuel flow method. The flight trajectory optimization is performed by a genetic algorithm (GA) with respect to a selected routing option. In the model development phase, benchmark tests were performed for the great circle and flight time routing options. The first test showed that the great circle calculations were accurate to -0.004 %, compared to those calculated by the Movable Type script. The second test showed that the optimal solution found by the algorithm sufficiently converged to the theoretical true-optimal solution. The difference in flight time between the two solutions is less than 0.01 %. The dependence of

  8. Simulation of the Westerly Jet Axis in Boreal Winter by the Climate System Model FGOALS-g2

    Institute of Scientific and Technical Information of China (English)

    XIAO Chuliang; ZHANG Yaocun

    2013-01-01

    The major features of the westerly jets in boreal winter,consisting of the Middle East jet stream (MEJS),East Asian jet stream (EAJS) and North Atlantic jet stream (NAJS),simulated by a newly developed climate system model,were evaluated with an emphasis on the meridional location of the westerly jet axis (WJA).The model was found to exhibit fairly good performance in simulating the EAJS and NAJS,whereas the MEJS was much weaker and indistinguishable in the model.Compared with the intensity bias,the southward shift of the WJA seems to be a more remarkable deficiency.From the perspective of Ertel potential vorticity,the profiles along different westerly jet cores in the model were similar with those in the reanalysis but all shifted southward,indicating an equatorward displacement of the dynamic tropopause and associated climatology.Diagnosis of the thermodynamic equation revealed that the model produced an overall stronger heating source and the streamfunction quantifying the convection and overturning Hadley circulation shifted southward significantly in the middle and upper troposphere.The two maximum centers of eddy kinetic energy,corresponding to the EAJS and NAJS,were reproduced,whereas they all shifted southwards with a much reduced intensity.A lack of transient eddy activity will reduce the efficiency of poleward heat transport,which may partially contribute to the meridionally non-uniform cooling in the middle and upper troposphere.As the WJA is closely related to the location of the Hadley cell,tropopause and transient eddy activity,the accurate simulation of westerly jets will greatly improve the atmospheric general circulation and associated climatology in the model.

  9. Connections between simulations and observation in climate computer modeling. Scientist's practices and "bottom-up epistemology" lessons

    Science.gov (United States)

    Guillemot, Hélène

    Climate modeling is closely tied, through its institutions and practices, to observations from satellites and to the field sciences. The validity, quality and scientific credibility of models are based on interaction between models and observation data. In the case of numerical modeling of climate and climate change, validation is not solely a scientific interest: the legitimacy of computer modeling, as a tool of knowledge, has been called into question in order to deny the reality of any anthropogenic climate change; model validations thereby bring political issues into play as well. There is no systematic protocol of validation: one never validates a model in general, but the capacity of a model to account for a defined climatic phenomenon or characteristic. From practices observed in the two research centers developing and using a climate model in France, this paper reviews different ways in which the researchers establish links between models and empirical data (which are not reduced to the latter validating the former) and convince themselves that their models are valid. The analysis of validation practices-relating to parametrization, modes of variability, climatic phenomena, etc.-allows us to highlight some elements of the epistemology of modeling.

  10. Tree-ring proxy based temperature reconstructions and climate model simulations: cross-comparison at the Pyrenees

    Directory of Open Access Journals (Sweden)

    I. Dorado Liñán

    2011-11-01

    Full Text Available May-to-September mean temperatures over the larger Pyrenees area (Northern Spain and Southern France are reconstructed for the last Millennium from 22 maximum density (MXD tree-ring chronologies. For the standardization of the tree-ring series, two detrending methods (Regional Curve Standardization (RCS and 300-yr spline were combined with and without an adaptive power transform (PT for variance stabilization in the individual series. Thus, four different standardization procedures were applied to the data. Additionally, different regional chronologies were generated by computing a mean composite, averaging the local chronologies, or by applying Principal Components Analysis (PCA to extract common variance from the subsets of individual MXD chronologies.

    Calibration-verification trials were performed using the product of the three regional aggregation methods in split periods: 1900–1952 and 1953–2006. Two methods were used to calibrate the regional chronology: regression and a simple variance-matching, sometimes also known as composite-plus-scaling. The resulting set of temperature reconstructions was compared with climate simulations performed with global (ECHO-G over the last Millennium for the target region and regional (MM5 climate models.

    The reconstructions reveal inter-annual to multi-centennial temperature variations at the Pyrenees region for the last 750 yr. Generally, variations at inter-decadal timescales, including the cold periods associated with the solar minima, are common to all reconstruction variants although some discrepancies are found at longer timescales.

    The simulations of the global circulation model ECHO-G and the regional model MM5 agree with the tree-ring based reconstructions at decadal to multi-decadal time-scales. However, the comparison also highlights differences that need to be understood, such as the amplitude of the temperature variations and the discrepancies regarding the 20th

  11. A New Weighting Function for Estimating Microwave Sounding Unit Channel 4 Temperature Trends Simulated by CMIP5 Climate Models

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xuanze; ZHENG Xiaogu; YANG Chi; LUO San

    2013-01-01

    A new static microwave sounding unit (MSU) channel 4 weighting function is obtained from using Coupled Model Inter-comparison Project,Phase 5 (CMIP5) historical multimodel simulations as inputs into the fast Radiative Transfer Model for TOVS (RTTOV vl0).For the same CMIP5 model simulations,it is demonstrated that the computed MSU channel 4 brightness temperature (T4) trends in the lower stratosphere over both the globe and the tropics using the proposed weighting function are equivalent to those calculated by RTTOV,but show more cooling than those computed using the traditional UAH (University of Alabama at Huntsville) or RSS (Remote Sensing Systems in Santa Rosa,California) static weighting functions.The new static weighting function not only reduces the computational cost,but also reveals reasons why trends using a radiative transfer model are different from those using a traditional static weighting function.This study also shows that CMIP5 model simulated T4 trends using the traditional UAH or RSS static weighting functions show less cooling than satellite observations over the globe and the tropics.Although not completely removed,this difference can be reduced using the proposed weighting function to some extent,especially over the tropics.This work aims to explore the reasons for the trend differences and to see to what extent they are related to the inaccurate weighting functions.This would also help distinguish other sources for trend errors and thus better understand the climate change in the lower stratosphere.

  12. The El Niño-Southern Oscillation cycle simulated by the climate system model of Chinese Academy of Sciences

    Institute of Scientific and Technical Information of China (English)

    SU Tonghua; XUE Feng; SUN Hongchuan; ZHOU Guangqing

    2015-01-01

    On the basis of more than 200-year control run, the performance of the climate system model of Chinese Academy of Sciences (CAS-ESM-C) in simulating the El Niño-Southern Oscillation (ENSO) cycle is evalu-ated, including the onset, development and decay of the ENSO. It is shown that, the model can reasonably simulate the annual cycle and interannual variability of sea surface temperature (SST) in the tropical Pacif-ic, as well as the seasonal phase-locking of the ENSO. The model also captures two prerequisites for the El Niño onset, i.e., a westerly anomaly and a warm SST anomaly in the equatorial western Pacific. Owing to too strong forcing from an extratropical meridional wind, however, the westerly anomaly in this region is largely overestimated. Moreover, the simulated thermocline is much shallower with a weaker slope. As a result, the warm SST anomaly from the western Pacific propagates eastward more quickly, leading to a faster develop-ment of an El Niño. During the decay stage, owing to a stronger El Niño in the model, the secondary Gill-type response of the tropical atmosphere to the eastern Pacific warming is much stronger, thereby resulting in a persistent easterly anomaly in the western Pacific. Meanwhile, a cold anomaly in the warm pool appears as a result of a lifted thermocline via Ekman pumping. Finally, an El Niño decays into a La Niña through their interactions. In addition, the shorter period and larger amplitude of the ENSO in the model can be attribut-ed to a shallower thermocline in the equatorial Pacific, which speeds up the zonal redistribution of a heat content in the upper ocean.

  13. Climate for Culture : assessing the impact of climate change on the future indoor climate in historic buildings using simulations

    OpenAIRE

    2015-01-01

    Background The present study reports results from the large-scale integrated EU project "Climate for Culture". The full name, or title, of the project is Climate for Culture: damage risk assessment, economic impact and mitigation strategies for sustainable preservation of cultural heritage in times of climate change. This paper focusses on implementing high resolution regional climate models together with new building simulation tools in order to predict future outdoor and indoor climate cond...

  14. Simulated long-term climate response to idealized solar geoengineering

    Science.gov (United States)

    Cao, Long; Duan, Lei; Bala, Govindasamy; Caldeira, Ken

    2016-03-01

    Solar geoengineering has been proposed as a potential means to counteract anthropogenic climate change, yet it is unknown how such climate intervention might affect the Earth's climate on the millennial time scale. Here we use the HadCM3L model to conduct a 1000 year sunshade geoengineering simulation in which solar irradiance is uniformly reduced by 4% to approximately offset global mean warming from an abrupt quadrupling of atmospheric CO2. During the 1000 year period, modeled global climate, including temperature, hydrological cycle, and ocean circulation of the high-CO2 simulation departs substantially from that of the control preindustrial simulation, whereas the climate of the geoengineering simulation remains much closer to that of the preindustrial state with little drift. The results of our study do not support the hypothesis that nonlinearities in the climate system would cause substantial drift in the climate system if solar geoengineering was to be deployed on the timescale of a millennium.

  15. Large-eddy simulation of stable atmospheric boundary layers to develop better turbulence closures for climate and weather models

    Science.gov (United States)

    Bou-Zeid, Elie; Huang, Jing; Golaz, Jean-Christophe

    2011-11-01

    A disconnect remains between our improved physical understanding of boundary layers stabilized by buoyancy and how we parameterize them in coarse atmospheric models. Most operational climate models require excessive turbulence mixing in such conditions to prevent decoupling of the atmospheric component from the land component, but the performance of such a model is unlikely to be satisfactory under weakly and moderately stable conditions. Using Large-eddy simulation, we revisit some of the basic challenges in parameterizing stable atmospheric boundary layers: eddy-viscosity closure is found to be more reliable due to an improved alignment of vertical Reynolds stresses and mean strains under stable conditions, but the dependence of the magnitude of the eddy viscosity on stability is not well represented by several models tested here. Thus, we propose a new closure that reproduces the different stability regimes better. Subsequently, tests of this model in the GFDL's single-column model (SCM) are found to yield good agreement with LES results in idealized steady-stability cases, as well as in cases with gradual and sharp changes of stability with time.

  16. Sensitivity of a regional climate model to land surface parameterization schemes for East Asian summer monsoon simulation

    Science.gov (United States)

    Li, Wenkai; Guo, Weidong; Xue, Yongkang; Fu, Congbin; Qiu, Bo

    2016-10-01

    Land surface processes play an important role in the East Asian Summer Monsoon (EASM) system. Parameterization schemes of land surface processes may cause uncertainties in regional climate model (RCM) studies for the EASM. In this paper, we investigate the sensitivity of a RCM to land surface parameterization (LSP) schemes for long-term simulation of the EASM. The Weather Research and Forecasting (WRF) Model coupled with four different LSP schemes (Noah-MP, CLM4, Pleim-Xiu and SSiB), hereafter referred to as Sim-Noah, Sim-CLM, Sim-PX and Sim-SSiB respectively, have been applied for 22-summer EASM simulations. The 22-summer averaged spatial distributions and strengths of downscaled large-scale circulation, 2-m temperature and precipitation are comprehensively compared with ERA-Interim reanalysis and dense station observations in China. Results show that the downscaling ability of RCM for the EASM is sensitive to LSP schemes. Furthermore, this study confirms that RCM does add more information to the EASM compared to reanalysis that imposes the lateral boundary conditions (LBC) because it provides 2-m temperature and precipitation that are with higher resolution and more realistic compared to LBC. For 2-m temperature and monsoon precipitation, Sim-PX and Sim-SSiB simulations are more consistent with observation than simulations of Sim-Noah and Sim-CLM. To further explore the physical and dynamic mechanisms behind the RCM sensitivity to LSP schemes, differences in the surface energy budget between simulations of Ens-Noah-CLM (ensemble mean averaging Sim-Noah and Sim-CLM) and Ens-PX-SSiB (ensemble mean averaging Sim-PX and Sim-SSiB) are investigated and their subsequent impacts on the atmospheric circulation are analyzed. It is found that the intensity of simulated sensible heat flux over Asian continent in Ens-Noah-CLM is stronger than that in Ens-PX-SSiB, which induces a higher tropospheric temperature in Ens-Noah-CLM than in Ens-PX-SSiB over land. The adaptive

  17. A Regulation of Tropical Climate by Radiative Cooling as Simulated in a Cumulus Ensemble Model

    Science.gov (United States)

    Sui, Chung-Hsiung; Lau, K.-M.; Li, X.; Chou, M.-D.; Einaudi, Franco (Technical Monitor)

    2000-01-01

    Responses of tropical atmosphere to low-boundary forcing are investigated in a 2-D cumulus ensemble model (CEM) with an imposed warm-pool and cold-pool SST contrast (deltaSST). The domain-mean vertical motion is constrained to produce heat sink and moisture source as in the observed tropical climate. In a series of experiments, the warm pool SST is specified at different values while the cold pool SST is specified at 26 C. The strength of the circulation increases with increasing deltaSST until deltaSST reaches 3.5 C, and remains unchanged as deltaSST exceeds 3.5 C. The regulation of tropical convection by zonal SST gradient is constrained by the radiative cooling over the cold pool. For deltaSST less than 3.5 C, an enhanced subsidence warming is balanced by a reduced condensation heating over the cold pool. For deltaSST greater than 3.5 C, the subsidence regime expands over the entire cold pool where no condensation heating exist so that a further enhanced subsidence warming can no longer be sustained. The above regulation mechanism is also evident in the change of energy at the top of the atmosphere (TOA) that is dominated by cloud and water vapor greenhouse effect (c (sub LW)) and G (sub clear). The change in shortwave radiation at TOA is largely cancelled between the warm pool and cold pool, likely due to the same imposed vertical motion in our experiments. For deltaSST less than 3.5 C, an increase of deltaSST is associated with a large increase in c (sub Lw) due to increased total clouds in response to enhanced SST-induced circulation. For deltaSST greater than 3.5 C, clouds over the warm pool decrease with increasing SST, and the change in c (sub LW) is much smaller. In both dSST regimes, the change in CLW is larger than the change in G(sub clear) which is slightly negative. However, in the case of uniform warming (deltaSST=0), DeltaG(sub clear), is positive, approximately 5 W per square meters per degree change of SST.

  18. Modeling the Effect of Climate Change on Large Fire Size, Counts, and Intensities Using the Large Fire Simulator (FSim)

    Science.gov (United States)

    Riley, K. L.; Haas, J. R.; Finney, M.; Abatzoglou, J. T.

    2013-12-01

    Changes in climate can be expected to cause changes in wildfire activity due to a combination of shifts in weather (temperature, precipitation, relative humidity, wind speed and direction) and vegetation. Changes in vegetation could include type conversions, altered forest structure, and shifts in species composition, the effects of which could be mitigated or exacerbated by management activities. Further, changes in suppression response and effectiveness may alter potential wildfire activity, as well as the consequences of wildfire. Feedbacks among these factors are extremely complex and uncertain. The ability to anticipate changes driven by fire weather (largely outside of human control) can lead to development of fire and fuel management strategies aimed at mitigating current and future risk. Therefore, in this study we focus on isolating the effects of climate-induced changes in weather on wildfire activity. Specifically, we investigated the effect of changes in weather on fire activity in the Canadian Rockies ecoregion, which encompasses Glacier National Park and several large wilderness areas to the south. To model the ignition, growth, and containment of wildfires, we used the Large Fire Simulator (FSim), which we coupled with current and projected future climatic conditions. Weather streams were based on data from 14 downscaled Global Circulation Models (GCMs) from the Coupled Model Intercomparison Project Phase 5 (CMIP5) using the Representative Concentration Pathways (RCP) 45 and 85 for the years 2040-2060. While all GCMs indicate increases in temperature for this area, which would be expected to exacerbate fire activity, precipitation predictions for the summer wildfire season are more variable, ranging from a decrease of approximately 50 mm to an increase of approximately 50 mm. Windspeeds are generally predicted to decrease, which would reduce rates of spread and fire intensity. The net effect of these weather changes on the size, number, and intensity

  19. Glacial marine carbon cycle sensitivities to Atlantic ocean circulation reorganization by coupled climate model simulations

    Directory of Open Access Journals (Sweden)

    M. O. Chikamoto

    2011-04-01

    Full Text Available A series of Last Glacial Maximum (LGM marine carbon cycle sensitivity experiments is conducted to test the effect of different physical processes, as simulated by two atmosphere-ocean general circulation model (AOGCM experiments, on the atmospheric pCO2. One AOGCM solution exhibits an increase in North Atlantic Deep Water (NADW formation, whereas the other mimics an increase in Antarctic Bottom Water (AABW associated with a weaker NADW. Due to enhanced gas solubility associated with lower sea surface temperature, both experiments generate a reduction of atmospheric pCO2 by about 20–23 ppm. However, neither a weakening of NADW nor an increase of AABW formation causes a large atmospheric pCO2 change. A marked enhancement in AABW formation is required to represent the reconstructed vertical gradient of dissolved inorganic carbon (DIC during LGM conditions. The efficiency of Southern Ocean nutrient utilization reduces in response to an enhanced AABW formation, which counteracts the circulation-induced ocean carbon uptake.

  20. Forecasting carbon budget under climate change and CO2 fertilization for subtropical region in China using integrated biosphere simulator (IBIS) model

    Science.gov (United States)

    Zhu, Q.; Jiang, H.; Liu, J.; Peng, C.; Fang, X.; Yu, S.; Zhou, G.; Wei, X.; Ju, W.

    2011-01-01

    The regional carbon budget of the climatic transition zone may be very sensitive to climate change and increasing atmospheric CO2 concentrations. This study simulated the carbon cycles under these changes using process-based ecosystem models. The Integrated Biosphere Simulator (IBIS), a Dynamic Global Vegetation Model (DGVM), was used to evaluate the impacts of climate change and CO2 fertilization on net primary production (NPP), net ecosystem production (NEP), and the vegetation structure of terrestrial ecosystems in Zhejiang province (area 101,800 km2, mainly covered by subtropical evergreen forest and warm-temperate evergreen broadleaf forest) which is located in the subtropical climate area of China. Two general circulation models (HADCM3 and CGCM3) representing four IPCC climate change scenarios (HC3AA, HC3GG, CGCM-sresa2, and CGCM-sresb1) were used as climate inputs for IBIS. Results show that simulated historical biomass and NPP are consistent with field and other modelled data, which makes the analysis of future carbon budget reliable. The results indicate that NPP over the entire Zhejiang province was about 55 Mt C yr-1 during the last half of the 21st century. An NPP increase of about 24 Mt C by the end of the 21st century was estimated with the combined effects of increasing CO2 and climate change. A slight NPP increase of about 5 Mt C was estimated under the climate change alone scenario. Forests in Zhejiang are currently acting as a carbon sink with an average NEP of about 2.5 Mt C yr-1. NEP will increase to about 5 Mt C yr-1 by the end of the 21st century with the increasing atmospheric CO2 concentration and climate change. However, climate change alone will reduce the forest carbon sequestration of Zhejiang's forests. Future climate warming will substantially change the vegetation cover types; warm-temperate evergreen broadleaf forest will be gradually substituted by subtropical evergreen forest. An increasing CO2 concentration will have little

  1. Eco-hydrologic model cascades: Simulating land use and climate change impacts on hydrology, hydraulics and habitats for fish and macroinvertebrates.

    Science.gov (United States)

    Guse, Björn; Kail, Jochem; Radinger, Johannes; Schröder, Maria; Kiesel, Jens; Hering, Daniel; Wolter, Christian; Fohrer, Nicola

    2015-11-15

    Climate and land use changes affect the hydro- and biosphere at different spatial scales. These changes alter hydrological processes at the catchment scale, which impact hydrodynamics and habitat conditions for biota at the river reach scale. In order to investigate the impact of large-scale changes on biota, a cascade of models at different scales is required. Using scenario simulations, the impact of climate and land use change can be compared along the model cascade. Such a cascade of consecutively coupled models was applied in this study. Discharge and water quality are predicted with a hydrological model at the catchment scale. The hydraulic flow conditions are predicted by hydrodynamic models. The habitat suitability under these hydraulic and water quality conditions is assessed based on habitat models for fish and macroinvertebrates. This modelling cascade was applied to predict and compare the impacts of climate- and land use changes at different scales to finally assess their effects on fish and macroinvertebrates. Model simulations revealed that magnitude and direction of change differed along the modelling cascade. Whilst the hydrological model predicted a relevant decrease of discharge due to climate change, the hydraulic conditions changed less. Generally, the habitat suitability for fish decreased but this was strongly species-specific and suitability even increased for some species. In contrast to climate change, the effect of land use change on discharge was negligible. However, land use change had a stronger impact on the modelled nitrate concentrations affecting the abundances of macroinvertebrates. The scenario simulations for the two organism groups illustrated that direction and intensity of changes in habitat suitability are highly species-dependent. Thus, a joined model analysis of different organism groups combined with the results of hydrological and hydrodynamic models is recommended to assess the impact of climate and land use changes on

  2. A vertically resolved, global, gap-free ozone database for assessing or constraining global climate model simulations

    Directory of Open Access Journals (Sweden)

    G. E. Bodeker

    2013-02-01

    Full Text Available High vertical resolution ozone measurements from eight different satellite-based instruments have been merged with data from the global ozonesonde network to calculate monthly mean ozone values in 5° latitude zones. These ''Tier 0'' ozone number densities and ozone mixing ratios are provided on 70 altitude levels (1 to 70 km and on 70 pressure levels spaced ~ 1 km apart (878.4 hPa to 0.046 hPa. The Tier 0 data are sparse and do not cover the entire globe or altitude range. To provide a gap-free database, a least squares regression model is fitted to the Tier 0 data and then evaluated globally. The regression model fit coefficients are expanded in Legendre polynomials to account for latitudinal structure, and in Fourier series to account for seasonality. Regression model fit coefficient patterns, which are two dimensional fields indexed by latitude and month of the year, from the N-th vertical level serve as an initial guess for the fit at the N + 1-th vertical level. The initial guess field for the first fit level (20 km/58.2 hPa was derived by applying the regression model to total column ozone fields. Perturbations away from the initial guess are captured through the Legendre and Fourier expansions. By applying a single fit at each level, and using the approach of allowing the regression fits to change only slightly from one level to the next, the regression is less sensitive to measurement anomalies at individual stations or to individual satellite-based instruments. Particular attention is paid to ensuring that the low ozone abundances in the polar regions are captured. By summing different combinations of contributions from different regression model basis functions, four different ''Tier 1'' databases have been compiled for different intended uses. This database is suitable for assessing ozone fields from chemistry-climate model simulations or for providing the ozone boundary conditions for global climate model simulations that do not

  3. A vertically resolved, global, gap-free ozone database for assessing or constraining global climate model simulations

    Directory of Open Access Journals (Sweden)

    G. E. Bodeker

    2012-10-01

    Full Text Available High vertical resolution ozone measurements from eight different satellite-based instruments have been merged with data from the global ozonesonde network to calculate monthly mean ozone values in 5° latitude zones. These "Tier 0" ozone number densities and ozone mixing ratios are provided on 70 altitude levels (1 to 70 km and on 70 pressure levels spaced ~1 km apart (878.4 hPa to 0.046 hPa. The Tier 0 data are sparse and do not cover the entire globe or altitude range. To provide a gap-free database, a least squares regression model is fitted to the Tier 0 data and then evaluated globally. The regression model fit coefficients are expanded in Legendre polynomials to account for latitudinal structure, and in Fourier series to account for seasonality. Regression model fit coefficient patterns, which are two dimensional fields indexed by latitude and month of the year, from the N-th vertical level serve as an initial guess for the fit at the N+1th vertical level. The initial guess field for the first fit level (20 km/58.2 hPa was derived by applying the regression model to total column ozone fields. Perturbations away from the initial guess are captured through the Legendre and Fourier expansions. By applying a single fit at each level, and using the approach of allowing the regression fits to change only slightly from one level to the next, the regression is less sensitive to measurement anomalies at individual stations or to individual satellite-based instruments. Particular attention is paid to ensuring that the low ozone abundances in the polar regions are captured. By summing different combinations of contributions from different regression model basis functions, four different "Tier 1" databases have been compiled for different intended uses. This database is suitable for assessing ozone fields from chemistry-climate model simulations or for providing the ozone boundary conditions for global climate model simulations that do

  4. Accelerating Climate Simulations Through Hybrid Computing

    Science.gov (United States)

    Zhou, Shujia; Sinno, Scott; Cruz, Carlos; Purcell, Mark

    2009-01-01

    Unconventional multi-core processors (e.g., IBM Cell B/E and NYIDIDA GPU) have emerged as accelerators in climate simulation. However, climate models typically run on parallel computers with conventional processors (e.g., Intel and AMD) using MPI. Connecting accelerators to this architecture efficiently and easily becomes a critical issue. When using MPI for connection, we identified two challenges: (1) identical MPI implementation is required in both systems, and; (2) existing MPI code must be modified to accommodate the accelerators. In response, we have extended and deployed IBM Dynamic Application Virtualization (DAV) in a hybrid computing prototype system (one blade with two Intel quad-core processors, two IBM QS22 Cell blades, connected with Infiniband), allowing for seamlessly offloading compute-intensive functions to remote, heterogeneous accelerators in a scalable, load-balanced manner. Currently, a climate solar radiation model running with multiple MPI processes has been offloaded to multiple Cell blades with approx.10% network overhead.

  5. Evaluation of surface air temperature and urban effects in Japan simulated by non-hydrostatic regional climate model

    Science.gov (United States)

    Murata, A.; Sasaki, H.; Hanafusa, M.; Kurihara, K.

    2012-12-01

    We evaluated the performance of a well-developed nonhydrostatic regional climate model (NHRCM) with a spatial resolution of 5 km with respect to temperature in the present-day climate of Japan, and estimated urban heat island (UHI) intensity by comparing the model results and observations. The magnitudes of root mean square error (RMSE) and systematic error (bias) for the annual average of daily mean (Ta), maximum (Tx), and minimum (Tn) temperatures are within 1.5 K, demonstrating that the temperatures of the present-day climate are reproduced well by NHRCM. These small errors indicate that temperature variability produced by local-scale phenomena is represented well by the model with a higher spatial resolution. It is also found that the magnitudes of RMSE and bias in the annually-average Tx are relatively large compared with those in Ta and Tn. The horizontal distributions of the error, defined as the difference between simulated and observed temperatures (simulated minus observed), illustrate negative errors in the annually-averaged Tn in three major metropolitan areas: Tokyo, Osaka, and Nagoya. These negative errors in urban areas affect the cold bias in the annually-averaged Tx. The relation between the underestimation of temperature and degree of urbanization is therefore examined quantitatively using National Land Numerical Information provided by the Ministry of Land, Infrastructure, Transport, and Tourism. The annually-averaged Ta, Tx, and Tn are all underestimated in the areas where the degree of urbanization is relatively high. The underestimations in these areas are attributed to the treatment of urban areas in NHRCM, where the effects of urbanization, such as waste heat and artificial structures, are not included. In contrast, in rural areas, the simulated Tx is underestimated and Tn is overestimated although the errors in Ta are small. This indicates that the simulated diurnal temperature range is underestimated. The reason for the relatively large

  6. Comparative analysis of the influence of climate change and nitrogen deposition on carbon sequestration in forest ecosystems in European Russia: simulation modelling approach

    OpenAIRE

    Komarov, A. S.; V. N. Shanin

    2012-01-01

    An individual-based simulation model, EFIMOD, was used to simulate the response of forest ecosystems to climate change and additional nitrogen deposition. The general scheme of the model includes forest growth depending on nitrogen uptake by plants and mineralization of soil organic matter. The mineralization rate is dependent on nitrogen content in litter and forest floor horizons. Three large forest areas in European Central Russia with a total area of about 17 000 km2

  7. Comparative analysis of the influence of climate change and nitrogen deposition on carbon sequestration in forest ecosystems in European Russia: simulation modelling approach

    OpenAIRE

    Komarov, A. S.; V. N. Shanin

    2012-01-01

    An individual-based simulation model, EFIMOD, was used to simulate the response of forest ecosystems to climate change and additional nitrogen deposition. The general scheme of the model includes forest growth depending on nitrogen uptake by plants and mineralization of soil organic matter. The mineralization rate is dependent on nitrogen content in litter and forest floor horizons. Three large forest areas in European Central Russia with a total area of about 17 000 km2 in ...

  8. Assessment of simulated rainfall and temperature from the regional climate model REMO and future changes over Central Africa

    Science.gov (United States)

    Fotso-Nguemo, Thierry C.; Vondou, Derbetini A.; Tchawoua, Clément; Haensler, Andreas

    2016-07-01

    This work investigates spatial and temporal changes in rainfall and temperature over Central Africa, using historical and representative concentration pathways (RCP2.6, RCP4.5 and RCP8.5) of the regional climate model REMO forced by two general climate models: the Europe-wide Consortium Earth System Model (EC-Earth) and the Max Planck Institute-Earth System Model (MPI-ESM). We found that in the present period (1980-2005), the spatial distribution of rainfall is simulated with an annual spatial pattern correlation coefficient (PCC) of 0.76 for REMO driven by EC-Earth and 0.74 for REMO driven by MPI-ESM respectively when compared to CRU data. In terms of temperature, the annual PCC is 0.93 for the two REMO outputs. According to the climatology of Central Africa, we subdivided the study area into five sub-regions, we also noticed that the annual and seasonal PCC depend on the considered sub-region. For the future period (2070-2095), temperature is projected to increase following all the three scenarios. The rainfall amount is projected to decrease by up to 5 mm/day towards the end of the twenty first century under RCP8.5 scenario, and by 1-2 mm/day under RCP4.5 and RCP2.6 scenarios over Equatorial Guinea, Gabon, Congo, north-western Democratic Republic of Congo (DRC) and the Lake Victoria. Significant decrease is predicted to occur mostly in the northern part of the domain under RCP8.5 scenario. However, future rainfall over High Lands of Cameroon, Adamawa Plateau, north-eastern DRC and Atlantic Ocean is projected to increase.

  9. Dynamical amplification of the stratospheric solar response simulated with the Chemistry-Climate Model LMDz-Reprobus

    Science.gov (United States)

    Marchand, M.; Keckhut, P.; Lefebvre, S.; Claud, C.; Cugnet, D.; Hauchecorne, A.; Lefèvre, F.; Lefebvre, M.-P.; Jumelet, J.; Lott, F.; Hourdin, F.; Thuillier, G.; Poulain, V.; Bossay, S.; Lemennais, P.; David, C.; Bekki, S.

    2012-02-01

    The impact of the 11-year solar cycle on the stratosphere and, in particular, on the polar regions is investigated using simulations from the Chemistry Climate Model (CCM) LMDz-Reprobus. The annual solar signal clearly shows a stratospheric response largely driven by radiative and photochemical processes, especially in the upper stratosphere. A month-by-months analysis suggests that dynamical feedbacks play an important role in driving the stratospheric response on short timescales. CCM outputs on a 10 days frequency indicate how, in the northern hemisphere, changes in solar heating in the winter polar stratosphere may influence the upward propagation of planetary waves and thus their deposition of momentum, ultimately modifying the strength of the mean stratospheric overtuning circulation at middle and high latitudes. The model results emphasize that the main temperature and wind responses in the northern hemisphere can be explained by a different timing in the occurrence of Sudden Stratospheric Warmings (SSWs) that are caused by small changes in planetary wave propagation depending on solar conditions. The differences between simulations forced by different solar conditions indicate successive positive and negative responses during the course of the winter. The solar minimum simulation generally indicates a slightly stronger polar vortex early in the winter while the solar maximum simulation experiences more early SSWs with a stronger wave-mean flow interaction and reduced zonal wind at mid-latitudes in the upper stratosphere. The opposite response is observed during mid-winter, in February, with more SSWs simulated for solar minimum conditions while solar maximum conditions are associated with a damped planetary wave activity and a reinforced vortex after the initial stratospheric warming period. In late winter, the response is again reversed, as noticed in the temperature differences, with major SSW mostly observed in the solar maximum simulation and less

  10. Regional Climate Simulations of the Hydrological Cycle in the Iberian Peninsula with a Coupled WRF-HYDRO Model

    Science.gov (United States)

    Rios-Entenza, A.; Miguez-Macho, G.

    2008-12-01

    Land-atmosphere water exchanges and heat fluxes play an important role in climate and particularly in controlling precipitation in water-limited regions. One of such regions is the Iberian Peninsula, and in this study we examine the relevance of water recycling in convective precipitation regimes of the Fall and Spring there, when rainfall is critical for agriculture and many other human activities. We conducted simulations with WRF-ARW model at 5 km horizontal resolution, using a 1500 km x 1500 km nested grid that covers the Iberian Peninsula, with a parent domain that uses spectral nudging in order to avoid the distortion of the large-scale circulation caused by the interaction of the modeled flow with the lateral boundaries of the nested grid. For land-surface interactions we coupled WRF with the LEAF-HYDRO land surface model, which includes water table dynamics. We use therefore a tool that simulates the entire water cycle, including the water table, which has been reported to be critical for soil moisture dynamics in semi-arid regions like the Iberian Peninsula. For each one of the events that we selected, we performed two simulations: a control one, where all land-atmosphere feedbacks are taken into account, and the experiment, where infiltration of the precipitated water into the soil was suppressed. In this manner we explore the role of upward latent and sensible heat fluxes and evapotranspiration in precipitation dynamics. Preliminary results suggest that water recycling is a key factor in extending convective precipitation during several days, and that the total new water added in the area as a whole is only a fraction of the total measured rainfall. An estimation of this fraction is very important to better understanding the water budget and for hydrological planning in this water-stressed region.

  11. Capability of a regional climate model to simulate climate variables requested for water balance computation: a case study over northeastern France

    Science.gov (United States)

    Boulard, Damien; Castel, Thierry; Camberlin, Pierre; Sergent, Anne-Sophie; Bréda, Nathalie; Badeau, Vincent; Rossi, Aurélien; Pohl, Benjamin

    2016-05-01

    This paper documents the capability of the ARW/WRF regional climate model to regionalize near-surface atmospheric variables at high resolution (8 km) over Burgundy (northeastern France) from daily to interannual timescales. To that purpose, a 20-year continuous simulation (1989-2008) was carried out. The WRF model driven by ERA-Interim reanalyses was compared to in situ observations and a mesoscale atmospheric analyses system (SAFRAN) for five near-surface variables: precipitation, air temperature, wind speed, relative humidity and solar radiation, the last four variables being used for the calculation of potential evapotranspiration (ET0). Results show a significant improvement upon ERA-Interim. This is due to a good skill of the model to reproduce the spatial distribution for all weather variables, in spite of a slight over-estimation of precipitation amounts mostly during the summer convective season, and wind speed during winter. As compared to the Météo-France observations, WRF also improves upon SAFRAN analyses, which partly fail at showing realistic spatial distributions for wind speed, relative humidity and solar radiation—the latter being strongly underestimated. The SAFRAN ET0 is thus highly under-estimated too. WRF ET0 is in better agreement with observations. In order to evaluate WRF's capability to simulate a reliable ET0, the water balance of thirty Douglas-fir stands was computed using a process-based model. Three soil water deficit indexes corresponding to the sum of the daily deviations between the relative extractible water and a critical value of 40 % below which the low soil water content affects tree growth, were calculated using the nearest weather station, SAFRAN analyses weather data, or by merging observation and WRF weather variables. Correlations between Douglas-fir growth and the three estimated soil water deficit indexes show similar results. These results showed through the ET0 estimation and the relation between mean annual SWDI

  12. Enabling Philippine Farmers to Adapt to Climate Variability Using Seasonal Climate and Weather Forecast with a Crop Simulation Model in an SMS-based Farmer Decision Support System

    Science.gov (United States)

    Ebardaloza, J. B. R.; Trogo, R.; Sabido, D. J.; Tongson, E.; Bagtasa, G.; Balderama, O. F.

    2015-12-01

    Corn farms in the Philippines are rainfed farms, hence, it is of utmost importance to choose the start of planting date so that the critical growth stages that are in need of water will fall on dates when there is rain. Most farmers in the Philippines use superstitions and traditions as basis for farming decisions such as when to start planting [1]. Before climate change, superstitions like planting after a feast day of a saint has worked for them but with the recent progression of climate change, farmers now recognize that there is a need for technological intervention [1]. The application discussed in this paper presents a solution that makes use of meteorological station sensors, localized seasonal climate forecast, localized weather forecast and a crop simulation model to provide recommendations to farmers based on the crop cultivar, soil type and fertilizer type used by farmers. It is critical that the recommendations given to farmers are not generic as each farmer would have different needs based on their cultivar, soil, fertilizer, planting schedule and even location [2]. This application allows the farmer to inquire about whether it will rain in the next seven days, the best date to start planting based on the potential yield upon harvest, when to apply fertilizer and by how much, when to water and by how much. Short messaging service (SMS) is the medium chosen for this application because while mobile penetration in the Philippines is as high as 101%, the smart phone penetration is only at 15% [3]. SMS has been selected as it has been identified as the most effective way of reaching farmers with timely agricultural information and knowledge [4,5]. The recommendations while derived from making use of Automated Weather Station (AWS) sensor data, Weather Research Forecasting (WRF) models and DSSAT 4.5 [9], are translated into the local language of the farmers and in a format that is easily understood as recommended in [6,7,8]. A pilot study has been started

  13. Simulation of long-term future climate changes with the green McGill paleoclimate model. The next glacial inception

    Energy Technology Data Exchange (ETDEWEB)

    Cochelin, A.S.B.; Mysak, L.A.; Wang, Zhaomin Wang [Department of Atmospheric and Oceanic Sciences, McGill University, 805 Sherbrooke Street West, Montreal, Quebec H3A 2K6 (Canada)

    2006-12-15

    The multi-component 'green' McGill Paleoclimate Model (MPM), which includes interactive vegetation, is used to simulate the next glacial inception under orbital and prescribed atmospheric CO2 forcing. This intermediate complexity model is first run for short-term periods with an increasing atmospheric CO2 concentration; the model's response is in general agreement with the results of GCMs for CO2 doubling. The green MPM is then used to derive projections of the climate for the next 100 kyr. Under a constant CO2 level, the model produces three types of evolution for the ice volume: an imminent glacial inception (low CO2 levels), a glacial inception in 50 kyr (CO2 levels of 280 or 290 ppm), or no glacial inception during the next 100 kyr (CO2 levels of 300 ppm and higher). This high sensitivity to the CO2 level is due to the exceptionally weak future variations of the summer insolation at high northern latitudes. The changes in vegetation re-inforce the buildup of ice sheets after glacial inception. Finally, if an initial global warming episode of finite duration is included, after which the atmospheric CO2 level is assumed to stabilize at 280, 290 or 300 ppm, the impact of this warming is seen only in the first 5 kyr of the run; after this time the response is insensitive to the early warming perturbation.

  14. Simulation of medicanes over the Mediterranean Sea in a regional climate model ensemble: impact of ocean-atmosphere coupling and increased resolution

    Science.gov (United States)

    Gaertner, Miguel Ángel; González-Alemán, Juan Jesús; Romera, Raquel; Domínguez, Marta; Gil, Victoria; Sánchez, Enrique; Gallardo, Clemente; Miglietta, Mario Marcello; Walsh, Kevin J. E.; Sein, Dmitry V.; Somot, Samuel; Dell'Aquila, Alessandro; Teichmann, Claas; Ahrens, Bodo; Buonomo, Erasmo; Colette, Augustin; Bastin, Sophie; van Meijgaard, Erik; Nikulin, Grigory

    2016-11-01

    Medicanes are cyclones over the Mediterranean Sea having a tropical-like structure but a rather small size, that can produce significant damage due to the combination of intense winds and heavy precipitation. Future climate projections, performed generally with individual atmospheric climate models, indicate that the intensity of the medicanes could increase under climate change conditions. The availability of large ensembles of high resolution and ocean-atmosphere coupled regional climate model (RCM) simulations, performed in MedCORDEX and EURO-CORDEX projects, represents an opportunity to improve the assessment of the impact of climate change on medicanes. As a first step towards such an improved assessment, we analyze the ability of the RCMs used in these projects to reproduce the observed characteristics of medicanes, and the impact of increased resolution and air-sea coupling on their simulation. In these storms, air-sea interaction plays a fundamental role in their formation and intensification, a different mechanism from that of extra-tropical cyclones, where the baroclinic instability mechanism prevails. An observational database, based on satellite images combined with high resolution simulations (Miglietta et al. in Geophys Res Lett 40:2400-2405, 2013), is used as a reference for evaluating the simulations. In general, the simulated medicanes do not coincide on a case-by-case basis with the observed medicanes. However, observed medicanes with a high intensity and relatively long duration of tropical characteristics are better replicated in simulations. The observed spatial distribution of medicanes is generally well simulated, while the monthly distribution reveals the difficulty of simulating the medicanes that first appear in September after the summer minimum in occurrence. Increasing the horizontal resolution has a systematic and generally positive impact on the frequency of simulated medicanes, while the general underestimation of their intensity is

  15. Aerosol microphysics simulations of the Mt.~Pinatubo eruption with the UM-UKCA composition-climate model

    Science.gov (United States)

    Dhomse, S. S.; Emmerson, K. M.; Mann, G. W.; Bellouin, N.; Carslaw, K. S.; Chipperfield, M. P.; Hommel, R.; Abraham, N. L.; Telford, P.; Braesicke, P.; Dalvi, M.; Johnson, C. E.; O'Connor, F.; Morgenstern, O.; Pyle, J. A.; Deshler, T.; Zawodny, J. M.; Thomason, L. W.

    2014-10-01

    We use a stratosphere-troposphere composition-climate model with interactive sulfur chemistry and aerosol microphysics, to investigate the effect of the 1991 Mount Pinatubo eruption on stratospheric aerosol properties. Satellite measurements indicate that shortly after the eruption, between 14 and 23 Tg of SO2 (7 to 11.5 Tg of sulfur) was present in the tropical stratosphere. Best estimates of the peak global stratospheric aerosol burden are in the range 19 to 26 Tg, or 3.7 to 6.7 Tg of sulfur assuming a composition of between 59 and 77 % H2SO4. In light of this large uncertainty range, we performed two main simulations with 10 and 20 Tg of SO2 injected into the tropical lower stratosphere. Simulated stratospheric aerosol properties through the 1991 to 1995 period are compared against a range of available satellite and in situ measurements. Stratospheric aerosol optical depth (sAOD) and effective radius from both simulations show good qualitative agreement with the observations, with the timing of peak sAOD and decay timescale matching well with the observations in the tropics and mid-latitudes. However, injecting 20 Tg gives a factor of 2 too high stratospheric aerosol mass burden compared to the satellite data, with consequent strong high biases in simulated sAOD and surface area density, with the 10 Tg injection in much better agreement. Our model cannot explain the large fraction of the injected sulfur that the satellite-derived SO2 and aerosol burdens indicate was removed within the first few months after the eruption. We suggest that either there is an additional alternative loss pathway for the SO2 not included in our model (e.g. via accommodation into ash or ice in the volcanic cloud) or that a larger proportion of the injected sulfur was removed via cross-tropopause transport than in our simulations. We also critically evaluate the simulated evolution of the particle size distribution, comparing in detail to balloon-borne optical particle counter (OPC

  16. Uncertainty in Simulating Wheat Yields Under Climate Change

    Energy Technology Data Exchange (ETDEWEB)

    Asseng, S.; Ewert, F.; Rosenzweig, C.; Jones, J.W.; Hatfield, Jerry; Ruane, Alex; Boote, K. J.; Thorburn, Peter; Rotter, R.P.; Cammarano, D.; Brisson, N.; Basso, B.; Martre, P.; Aggarwal, P.K.; Angulo, C.; Bertuzzi, P.; Biernath, C.; Challinor, AJ; Doltra, J.; Gayler, S.; Goldberg, R.; Grant, Robert; Heng, L.; Hooker, J.; Hunt, L.A.; Ingwersen, J.; Izaurralde, Roberto C.; Kersebaum, K.C.; Mueller, C.; Naresh Kumar, S.; Nendel, C.; O' Leary, G.O.; Olesen, JE; Osborne, T.; Palosuo, T.; Priesack, E.; Ripoche, D.; Semenov, M.A.; Shcherbak, I.; Steduto, P.; Stockle, Claudio O.; Stratonovitch, P.; Streck, T.; Supit, I.; Tao, F.; Travasso, M.; Waha, K.; Wallach, D.; White, J.W.; Williams, J.R.; Wolf, J.

    2013-09-01

    Anticipating the impacts of climate change on crop yields is critical for assessing future food security. Process-based crop simulation models are the most commonly used tools in such assessments1,2. Analysis of uncertainties in future greenhouse gas emissions and their impacts on future climate change has been increasingly described in the literature3,4 while assessments of the uncertainty in crop responses to climate change are very rare. Systematic and objective comparisons across impact studies is difficult, and thus has not been fully realized5. Here we present the largest coordinated and standardized crop model intercomparison for climate change impacts on wheat production to date. We found that several individual crop models are able to reproduce measured grain yields under current diverse environments, particularly if sufficient details are provided to execute them. However, simulated climate change impacts can vary across models due to differences in model structures and algorithms. The crop-model component of uncertainty in climate change impact assessments was considerably larger than the climate-model component from Global Climate Models (GCMs). Model responses to high temperatures and temperature-by-CO2 interactions are identified as major sources of simulated impact uncertainties. Significant reductions in impact uncertainties through model improvements in these areas and improved quantification of uncertainty through multi-model ensembles are urgently needed for a more reliable translation of climate change scenarios into agricultural impacts in order to develop adaptation strategies and aid policymaking.

  17. Comparative Visualization of Climate Simulation Data

    Science.gov (United States)

    Röber, Niklas; Meier-Fleischer, Karin; Böttinger, Michael

    2014-05-01

    Visualization is the process of transforming abstract (scientific) data into a graphical representation, to aid in the understanding of the information contained within the data. Climate data sets are typically quite large, time varying, and consist of many different variables that are sampled on an underlying grid. A variety of different climate models - and sub models - are developed to simulate the climate system and its components, such as the physics of the atmosphere and the ocean, marine biogeochemical processes and the land biosphere. Visualization software is used to assist in the process of visualization and data analysis by transforming the abstract numerical information into a graphical illustration. Different approaches exist in the design of visualization software and for the process of visualization itself, depending on the type and nature of the data as well as on the visualization goal. In addition to a large high performance compute cluster that is exclusively used for climate simulations, the German Climate Computing Centre (DKRZ) also hosts a dedicated visualization cluster for post-processing, data analysis and visualization. On this visualization server, a variety of software is installed to assist the user in the data visualization task. Amongst others, the software stack includes Avizo Green, CDO, NCL, Paraview and SimVis. Each tool has its own strengths and weaknesses, and is selected by the user with regard to the visualization goal. While Avizo Green is great for visualizing the data out of the box, SimVis and Paraview are better suited for an interactive and explorative data analysis. This PICO presentation uses several different visualization solutions - among them Avizo Green, NCL, Paraview and SimVis - to analyze and visualize the same climate data set. We will thereby explicitly focus on each software's strengths, and not highlight its weaknesses. This PICO interactively shows that - depending on the visualization tool used - not

  18. Regional climate model simulations for Europe at 6 k and 0.2 k yr BP: sensitivity to changes in anthropogenic deforestation

    Directory of Open Access Journals (Sweden)

    G. Strandberg

    2013-10-01

    Full Text Available This study aims to evaluate the direct effects of anthropogenic deforestation on simulated climate at two contrasting periods in the Holocene, ~6 k BP and ~0.2 k BP in Europe. We apply RCA3, a regional climate model with 50 km spatial resolution, for both time periods, considering three alternative descriptions of the past vegetation: (i potential natural vegetation (V simulated by the dynamic vegetation model LPJ-GUESS, (ii potential vegetation with anthropogenic land cover (deforestation as simulated by the HYDE model (V + H, and (iii potential vegetation with anthropogenic land cover as simulated by the KK model (V + K. The KK model estimates are closer to a set of pollen-based reconstructions of vegetation cover than the HYDE model estimates. The climate-model results show that the simulated effects of deforestation depend on both local/regional climate and vegetation characteristics. At ~6 k BP the extent of simulated deforestation in Europe is generally small, but there are areas where deforestation is large enough to produce significant differences in summer temperatures of 0.5–1 °C. At ~0.2 k BP, simulated deforestation is much more extensive than previously assumed, in particular according to the KK model. This leads to significant temperature differences in large parts of Europe in both winter and summer. In winter, deforestation leads to lower temperatures because of the differences in albedo between forested and unforested areas, particularly in the snow-covered regions. In summer, deforestation leads to higher temperatures in central and eastern Europe since evapotranspiration from unforested areas is lower than from forests. Summer evaporation is already limited in the southernmost parts of Europe under potential vegetation conditions and, therefore, cannot become much lower. Accordingly, the albedo effect dominates also in summer, which implies that deforestation causes a decrease in temperatures. Differences in summer

  19. Natural variability of CO2 and O2 fluxes: What can we learn from centuries-long climate models simulations?

    Science.gov (United States)

    Resplandy, L.; Séférian, R.; Bopp, L.

    2015-01-01

    carbon uptake and oxygen content estimates over the past decades suggest that the anthropogenic carbon sink has changed and that the oxygen concentration in the ocean interior has decreased. Although these detected changes appear consistent with those expected from anthropogenic forced climate change, large uncertainties remain in the contribution of natural variability. Using century-long simulations (500-1000 years) of unforced natural variability from six Earth System Models (ESMs), we examine the internally driven natural variability of carbon and oxygen fluxes from interannual to multidecadal time scales. The intensity of natural variability differs between the ESMs, in particular, decadal variability locally accounts for 10-50% of the total variance. Although the variability is higher in all regions with strong climate modes (North Atlantic, North Pacific, etc.), we find that only the Southern Ocean and the tropical Pacific significantly modulate the global fluxes. On (multi)decadal time scales, deep convective events along the Antarctic shelf drive the global fluxes variability by transporting deep carbon-rich/oxygen-depleted waters to the surface and by reducing the sea-ice coverage. On interannual time scales, the global flux is modulated by (1) variations of the upwelling of circumpolar deep waters associated with the southern annular mode in the subpolar Southern Ocean and (2) variations of the equatorial/costal upwelling combined with changes in the solubility-driven fluxes in response to El Niño Southern Oscillation (ENSO) in the tropical Pacific. We discuss the challenges of measuring and detecting long-term trends from a few decade-long records influenced by internal variability.

  20. Coupled atmosphere ocean climate model simulations in the Mediterranean region: effect of a high-resolution marine model on cyclones and precipitation

    Directory of Open Access Journals (Sweden)

    A. Sanna

    2013-06-01

    Full Text Available In this study we investigate the importance of an eddy-permitting Mediterranean Sea circulation model on the simulation of atmospheric cyclones and precipitation in a climate model. This is done by analyzing results of two fully coupled GCM (general circulation models simulations, differing only for the presence/absence of an interactive marine module, at very high-resolution (~ 1/16°, for the simulation of the 3-D circulation of the Mediterranean Sea. Cyclones are tracked by applying an objective Lagrangian algorithm to the MSLP (mean sea level pressure field. On annual basis, we find a statistically significant difference in vast cyclogenesis regions (northern Adriatic, Sirte Gulf, Aegean Sea and southern Turkey and in lifetime, giving evidence of the effect of both land–sea contrast and surface heat flux intensity and spatial distribution on cyclone characteristics. Moreover, annual mean convective precipitation changes significantly in the two model climatologies as a consequence of differences in both air–sea interaction strength and frequency of cyclogenesis in the two analyzed simulations.

  1. Antarctic 20th Century Accumulation Changes Based on Regional Climate Model Simulations

    Directory of Open Access Journals (Sweden)

    Klaus Dethloff

    2010-01-01

    investigated on the basis of ERA-40 data and HIRHAM simulations. It is shown that the regional accumulation changes are largely driven by changes in the transient activity around the Antarctic coasts due to the varying AAO phases. During positive AAO, more transient pressure systems travelling towards the continent, and Western Antarctica and parts of South-Eastern Antarctica gain more precipitation and mass. Over central Antarctica the prevailing anticyclone causes a strengthening of polar desertification connected with a reduced surface mass balance in the northern part of East Antarctica.

  2. Influence of ecohydrologic feedbacks from simulated crop growth on integrated regional hydrologic simulations under climate scenarios

    NARCIS (Netherlands)

    Walsum, van P.E.V.; Supit, I.

    2012-01-01

    Hydrologic climate change modelling is hampered by climate-dependent model parameterizations. To reduce this dependency, we extended the regional hydrologic modelling framework SIMGRO to host a two-way coupling between the soil moisture model MetaSWAP and the crop growth simulation model WOFOST, acc

  3. A global model simulation of present and future nitrate aerosols and their direct radiative forcing of climate

    Science.gov (United States)

    Hauglustaine, D. A.; Balkanski, Y.; Schulz, M.

    2014-10-01

    The ammonia cycle and nitrate particle formation are introduced into the LMDz-INCA (Laboratoire de Météorologie Dynamique, version 4 - INteraction with Chemistry and Aerosols, version 3) global model. An important aspect of this new model is that both fine nitrate particle formation in the accumulation mode and coarse nitrate forming on existing dust and sea-salt particles are considered. The model simulates distributions of nitrates and related species in agreement with previous studies and observations. The calculated present-day total nitrate direct radiative forcing since the pre-industrial is -0.056 W m-2. This forcing corresponds to 18% of the sulfate forcing. Fine particles largely dominate the nitrate forcing, representing close to 90% of this value. The model has been used to investigate the future changes in nitrates and direct radiative forcing of climate based on snapshot simulations for the four representative concentration pathway (RCP) scenarios and for the 2030, 2050, and 2100 time horizons. Due to a decrease in fossil fuel emissions in the future, the concentration of most of the species involved in the nitrate-ammonium-sulfate system drop by 2100 except for ammonia, which originates from agricultural practices and for which emissions significantly increase in the future. Despite the decrease of nitrate surface levels in Europe and North America, the global burden of accumulation mode nitrates increases by up to a factor of 2.6 in 2100. This increase in ammonium nitrate in the future arises despite decreasing NOx emissions due to increased availability of ammonia to form ammonium nitrate. The total aerosol direct forcing decreases from its present-day value of -0.234 W m-2 to a range of -0.070 to -0.130 W m-2 in 2100 based on the considered scenario. The direct forcing decreases for all aerosols except for nitrates, for which the direct negative forcing increases to a range of -0.060 to -0.115 W m-2 in 2100. Including nitrates in the radiative

  4. Assessing the role of deep rooted vegetation in the climate system with model simulations: mechanism, comparison to observations and implications for Amazonian deforestation

    Energy Technology Data Exchange (ETDEWEB)

    Kleidon, A.; Heimann, M. [Max-Planck-Institut fuer Meteorologie, Hamburg (Germany)

    2000-02-01

    Deep rooted vegetation (of up to 68 m) has been found in many parts of the tropics. However, models of the general atmospheric circulation (GCMs) typically use rooting depths of less than 2 m in their land surface parametrizations. How does the incorporation of deep roots into such a model affect the simulated climate? We assess this question by using a GCM and find that deeper roots lead to a pronounced seasonal response. During the dry season, evapotranspiration and the associated latent heat flux are considerably increased over large regions leading to a cooling of up to 8 K. The enhanced atmospheric moisture is transported towards the main convection areas in the inner tropical convergence zone where it supplies more energy to convection thus intensifying the tropical circulation patterns. Comparison to different kinds of data reveals that the simulation with deeper roots is much closer to observations. The inclusion of deep roots also leads to a general increased climatic sensitivity to rooting depth change. We investigate this aspect in the context of the climatic effects of large-scale deforestation in Amazonia. Most of the regional and remote changes can be attributed to the removal of deep roots. We conclude that deep rooted vegetation is an important part of the tropical climate system. Without the consideration of deep roots, the present-day surface climate cannot adequately be simulated. (orig.)

  5. A global model simulation of present and future nitrate aerosols and their direct radiative forcing of climate

    Directory of Open Access Journals (Sweden)

    D. A. Hauglustaine

    2014-03-01

    Full Text Available The ammonia cycle and nitrate particle formation have been introduced in the LMDz-INCA global model. Both fine nitrate particles formation in the accumulation mode and coarse nitrate forming on existing dust and sea-salt particles are considered. The model simulates distributions of nitrates and related species in agreement with previous studies and observations. The calculated present-day total nitrate direct radiative forcing since the pre-industrial is −0.056 W m−2. This forcing has the same magnitude than the forcing associated with organic carbon particles and represents 18% of the sulfate forcing. Fine particles largely dominate the nitrate forcing representing close to 90% of this value. The model has been used to investigate the future changes in nitrates and direct radiative forcing of climate based on snapshot simulations for the four Representative Concentration Pathway (RCP scenarios and for the 2030, 2050 and 2100 time horizons. Due to a decrease in fossil fuel emissions in the future, the concentrations of most of the species involved in the nitrate-ammonium-sulfate system drop by 2100 except for ammonia which originates from agricultural practices and for which emissions significantly increase in the future. Despite the decrease of nitrate surface levels in Europe and Northern America, the global burden of accumulation mode nitrates increases by up to a factor of 2.6 in 2100. This increase in nitrate in the future arises despite decreasing NOx emissions due to increased availability of ammonia to form ammonium nitrate. The total aerosol direct forcing decreases from its present-day value of −0.234 W m−2 to a range of −0.070 to −0.130 W m−2 in 2100 based on the considered scenario. The direct forcing decreases for all aerosols except for nitrates for which the direct negative forcing increases to a range of −0.060 to −0.115 W m−2 in 2100. Including nitrates in the radiative forcing calculations increases the

  6. Evaluation of Mediterranean Sea water and heat budgets simulated by an ensemble of high resolution regional climate models

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez-Gomez, E. [CERFACS/CNRS, SUC URA1875, Toulouse Cedex (France); Somot, S.; Dubois, C.; Deque, M. [CNRM/GAME, Meteo-France/CNRS, Toulouse (France); Josey, S.A. [National Oceanography Centre, Southampton (United Kingdom); Elguindi, N. [LA, CNRS, Toulouse (France)

    2011-11-15

    Air-sea heat and freshwater water fluxes in the Mediterranean Sea play a crucial role in dense water formation. Here, we compare estimates of Mediterranean Sea heat and water budgets from a range of observational datasets and discuss the main differences between them. Taking into account the closure hypothesis at the Gibraltar Strait, we have built several observational estimates of water and heat budgets by combination of their different observational components. We provide then three estimates for water budget and one for heat budget that satisfy the closure hypothesis. We then use these observational estimates to assess the ability of an ensemble of ERA40-driven high resolution (25 km) Regional Climate Models (RCMs) from the FP6-EU ENSEMBLES database, to simulate the various components, and net values, of the water and heat budgets. Most of the RCM Mediterranean basin means are within the range spanned by the observational estimates of the different budget components, though in some cases the RCMs have a tendency to overestimate the latent heat flux (or evaporation) with respect to observations. The RCMs do not show significant improvements of the total water budget estimates comparing to ERA40. Moreover, given the large spread found in observational estimates of precipitation over the sea, it is difficult to draw conclusions on the performance of RCM for the freshwater budget and this underlines the need for better precipitation observations. The original ERA40 value for the basin mean net heat flux is -15 W/m{sup 2} which is 10 W/m{sup 2} less than the value of -5 W/m{sup 2} inferred from the transport measurements at Gibraltar Strait. The ensemble of heat budget values estimated from the models show that most of RCMs do not achieve heat budget closure. However, the ensemble mean value for the net heat flux is -7 {+-} 21 W/m{sup 2}, which is close to the Gibraltar value, although the spread between the RCMs is large. Since the RCMs are forced by the same

  7. East Asian monsoon climate simulated in the PlioMIP

    Directory of Open Access Journals (Sweden)

    R. Zhang

    2013-02-01

    Full Text Available Based on the simulations with fifteen climate models in the Pliocene Model Intercomparison Project (PlioMIP, the regional climate of East Asia (focusing on China during the mid-Pliocene is investigated in this study. Compared to the pre-industrial, the multi-model ensemble mean (MMM of all models shows the East Asian summer wind (EASW largely strengthens in monsoon China, and the East Asian winter wind (EAWW strengthens in south monsoon China but slightly weakens in north monsoon China in mid-Pliocene. The MMM of all models also illustrates a warmer and wetter mid-Pliocene climate in China. The simulated weakened mid-Pliocene EAWW in north monsoon China and intensified EASW in monsoon China agree well with geological reconstructions. However, the model-model discrepancy in simulating mid-Pliocene East Asian monsoon climate, in particular EAWW, should be further addressed in the future work of PlioMIP.

  8. Simulating the Hydrologic Effects of Climate Change in 5 Research Watersheds using a Distributed-Parameter Watershed Model

    Science.gov (United States)

    Walker, J. F.; Hunt, R.; Aulenbach, B. T.; Clow, D. W.; Murphy, S.; Shanley, J. B.; Scholl, M. A.; Hay, L.; Regan, R. S.; Markstrom, S. L.

    2013-12-01

    A new focus of the U.S. Geological Survey's Water, Energy, and Biogeochemical Budgets (WEBB) program is the development of watershed models to predict hydrologic response to future conditions including land-use and climate change. Fine-scale models of 5 WEBB watersheds were constructed and embedded in coarse-scale models of larger stream systems. The WEBB watersheds range in size from 41 to 3,260 hectares; the coarse-scale models range in size from 1,100 to 4,800 square kilometers. The coarse-scale models were calibrated using data collected from 1980 to 2012 and included streamflow, snow-water equivalent (where appropriate), and seasonal distributions of solar radiation and potential evapotranspiration. Solar radiation and potential evapotranspiration were retrieved from a national gridded dataset using the USGS Geodata Portal (GDP) tool. Snowpack data was available as a national gridded dataset from December 2003 through November 2012, and was retrieved using the GDP. A stepwise approach was taken to identify specific hydrologic processes pertinent to the calibration targets. Calibration was carried out using the Parameter ESTimation (PEST) suite of automated calibration tools. Several climate models and three emission scenarios were selected from a range of Intergovernmental Panel on Climate Change (IPCC) climate projections to investigate the potential hydrologic effects of climate change in the WEBB watersheds. The GDP was used to construct input data sets for each coarse-scale model using a national dataset of downscaled climate data. Comparisons include projected changes in the dominant hydrologic processes across the five WEBB headwater basins, as well as, differences between headwater streams and higher-order streams at a regional scale.

  9. Obliquity and Precession in the Quaternary: Analyzing Climate Responses Using Single-Forcing GCM Simulations and Bayesian Model-Proxy Comparison

    Science.gov (United States)

    Erb, M. P.; Jackson, C. S.; Broccoli, A. J.; Lea, D. W.

    2015-12-01

    We present a detection and attribution approach to interpret the forcings and feedbacks that shaped Quaternary climate stemming from known variations in Earth's obliquity, precession, greenhouse gases, and ice sheet extent. Because future climate changes will be driven largely by only one forcing, CO2, it is important to better separate and understand the individual contributions of different forcings in producing past recorded changes. We use idealized equilibrium GCM simulations to fingerprint the annual mean and seasonal responses to individual changes in obliquity, precession, CO2, and ice sheets. These idealized "fingerprint" simulations are scaled by time series of past forcings and summed together to create a time-varying linear reconstruction of past climate that can be compared against proxy records. A multiple linear regression is conducted using Bayesian inference between the components of the linear reconstruction and long proxy time series, such as temperature from deuterium in Antarctic ice cores, to determine whether the modeled response to each forcing needs to be stronger or weaker to better match the data. This methodology offers a simple framework for exploring uncertainties affecting the interpretation of long time series of Quaternary climate variability and a way to use proxy data to test climate response processes relevant to future climate change.

  10. Uncertainty in simulating wheat yields under climate change

    DEFF Research Database (Denmark)

    Asseng, A; Ewert, F; Rosenzweig, C

    2013-01-01

    of environments, particularly if the input information is sufficient. However, simulated climate change impacts vary across models owing to differences in model structures and parameter values. A greater proportion of the uncertainty in climate change impact projections was due to variations among crop models...... than to variations among downscaled general circulation models. Uncertainties in simulated impacts increased with CO2 concentrations and associated warming. These impact uncertainties can be reduced by improving temperature and CO2 relationships in models and better quantified through use of multi......Projections of climate change impacts on crop yields are inherently uncertain1. Uncertainty is often quantified when projecting future greenhouse gas emissions and their influence on climate2. However, multi-model uncertainty analysis of crop responses to climate change is rare because systematic...

  11. Understanding and simulating the link between African easterly waves and Atlantic tropical cyclones using a regional climate model: the role of domain size and lateral boundary conditions

    Energy Technology Data Exchange (ETDEWEB)

    Caron, Louis-Philippe [MISU, Stockholm University, Stockholm (Sweden); Universite du Quebec a Montreal, CRCMD Network, Montreal, QC (Canada); Jones, Colin G. [Swedish Meterological and Hydrological Institute, Rossby Center, Norrkoeping (Sweden)

    2012-07-15

    Using a suite of lateral boundary conditions, we investigate the impact of domain size and boundary conditions on the Atlantic tropical cyclone and african easterly Wave activity simulated by a regional climate model. Irrespective of boundary conditions, simulations closest to observed climatology are obtained using a domain covering both the entire tropical Atlantic and northern African region. There is a clear degradation when the high-resolution model domain is diminished to cover only part of the African continent or only the tropical Atlantic. This is found to be the result of biases in the boundary data, which for the smaller domains, have a large impact on TC activity. In this series of simulations, the large-scale Atlantic atmospheric environment appears to be the primary control on simulated TC activity. Weaker wave activity is usually accompanied by a shift in cyclogenesis location, from the MDR to the subtropics. All ERA40-driven integrations manage to capture the observed interannual variability and to reproduce most of the upward trend in tropical cyclone activity observed during that period. When driven by low-resolution global climate model (GCM) integrations, the regional climate model captures interannual variability (albeit with lower correlation coefficients) only if tropical cyclones form in sufficient numbers in the main development region. However, all GCM-driven integrations fail to capture the upward trend in Atlantic tropical cyclone activity. In most integrations, variations in Atlantic tropical cyclone activity appear uncorrelated with variations in African easterly wave activity. (orig.)

  12. Influence of feedbacks from simulated crop growth on integrated regional hydrologic simulations under climate scenarios

    NARCIS (Netherlands)

    Walsum, van P.E.V.

    2011-01-01

    Climate change impact modelling of hydrologic responses is hampered by climate-dependent model parameterizations. Reducing this dependency was one of the goals of extending the regional hydrologic modelling system SIMGRO with a two-way coupling to the crop growth simulation model WOFOST. The couplin

  13. Multi-year Simulations and Experimental Seasonal Predictions for Rainy Seasons in China by Using a Nested Regional Climate Model (RegCM_NCC). Part Ⅰ: Sensitivity Study

    Institute of Scientific and Technical Information of China (English)

    DING Yihui; SHI Xueli; LIU Yiming; LIU Yan; LI Qingquan; QIAN Yongfu; MIAO Manqian; ZHAI Guoqing; GAO Kun

    2006-01-01

    A modified version of the NCAR/RegCM2 has been developed at the National Climate Center (NCC), China Meteorological Administration, through a series of sensitivity experiments and multi-year simulations and hindcasts, with a special emphasis on the adequate choice of physical parameterization schemes suitable for the East Asian monsoon climate. This regional climate model is nested with the NCC/IAP (Institute of Atmospheric Physics) T63 coupled GCM to make an experimental seasonal prediction for China and East Asia. The four-year (2001 to 2004) prediction results are encouraging. This paper is the first part of a two-part paper, and it mainly describes the sensitivity study of the physical process parameterization represented in the model. The systematic errors produced by the different physical parameterization schemes such as the land surface processes, convective precipitation, cloud-radiation transfer process, boundary layer process and large-scale terrain features have been identified based on multi-year and extreme flooding event simulations. A number of comparative experiments has shown that the mass flux scheme (MFS) and Betts-Miller scheme (BM) for convective precipitation, the LPMI (land surface process model I) and LPMII (land surface process model Ⅱ) for the land surface process, the CCM3 radiation transfer scheme for cloud-radiation transfer processes, the TKE (turbulent kinetic energy) scheme for the boundary layer processes and the topography treatment schemes for the Tibetan Plateau are suitable for simulations and prediction of the East Asia monsoon climate in rainy seasons. Based on the above sensitivity study, a modified version of the RegCM2 (RegCM_NCC) has been set up for climate simulations and seasonal predictions.

  14. Shifts of climate zones in multi-model climate change experiments using the Koeppen climate classification

    Energy Technology Data Exchange (ETDEWEB)

    Hanf, Franziska; Koerper, Janina; Spangehl, Thomas; Cubash, Ulrich [Freie Univ. Berlin (Germany). Inst. fuer Meteorologie

    2012-04-15

    This study investigates the future changes in the climate zones' distribution of the Earth's land area due to increasing atmospheric greenhouse gas concentrations in three IPCC SRES emissions scenarios (A1B, A2 and B1). The Koeppen climate classification is applied to climate simulations of seven atmosphere-ocean general circulation models (AOGCMs) and their multi-model mean. The evaluation of the skill of the individual climate models compared to an observation-reanalysis-based climate classification provides a first order estimate of relevant model uncertainties and serves as assessment for the confidence in the scenario projections. Uncertainties related to differences in simulation pathways of the future projections are estimated by both, the multi-model ensemble spread of the climate change signals for a given scenario and differences between different scenarios. For the recent climate the individual models fail to capture the exact Koeppen climate types in about 24-39 % of the global land area excluding Antarctica due to temperature and precipitation biases, while the multi-model ensemble mean simulates the present day observation-reanalysis-based distribution of the climate types more accurately. For the end of the 21{sup st} century compared to the present day climate the patterns of change are similar across the three scenarios, while the magnitude of change is largest for the highest emission scenario. Moreover, the temporal development of the climate shifts from the end of the 20st century and during the 21{sup st} century show that changes of the multi-model ensemble mean for the A2 and B1 scenario are generally within the ensemble spread of the individual models for the A1B scenario, illustrating that for the given range of scenarios the model uncertainty is even larger than the spread given by the different GHG concentration pathways. The multi-model ensemble mean's projections show climate shifts to dryer climates in the subtropics

  15. Glacial-interglacial variability in Tropical Pangaean Precipitation during the Late Paleozoic Ice Age: simulations with the Community Climate System Model

    Directory of Open Access Journals (Sweden)

    N. G. Heavens

    2012-05-01

    Full Text Available The Late Paleozoic Ice Age (LPIA, the Earth's penultimate "icehouse climate", was a critical time in the history of biological and ecological evolution. Many questions remain about the connections between high-latitude glaciation in Gondwanaland and low-latitude precipitation variability in Pangaea. We have simulated the Earth's climate during Asselian-Sakmarian time (299–284 Ma with the Community Climate System Model version 3 (CCSM3, a coupled dynamic atmosphere-ocean-land-sea-ice model. Our simulations test the sensitivity of the model climate to direct and indirect effects of glaciation as well as variability in the Earth's orbit. Our focus is on precipitation variability in tropical (30° S–30° N Pangaea, where there has been the most interpretation of glacial-interglacial climate change during the LPIA. The results of these simulations suggest that glacials generally were drier than interglacials in tropical Pangaea, though exceptional areas may have been wetter, depending on location and the mode of glaciation. Lower sea level, an indirect effect of changes in glacial extent, appears to reduce tropical Pangaean precipitation more than the direct radiative/topographic effects of high-latitude glaciation. Glaciation of the Central Pangaean Mountains would have greatly reduced equatorial Pangaean precipitation, while perhaps enhancing precipitation at higher tropical latitudes and in equatorial rain shadows. Variability evident in strata with 5th order stratigraphic cycles may have resulted from precipitation changes owing to precession forcing of monsoon circulations and would have differed in character between greenhouse and icehouse climates.

  16. Improved climatic chamber for desiccation simulation

    Directory of Open Access Journals (Sweden)

    Lozada Catalina

    2016-01-01

    Full Text Available The climatic chamber at the Universidad de Los Andes was improved for modeling desiccation in soil layers. This chamber allows the measurement of different environmental variables. In this research, evaporation tests were conducted in water imposing boundary conditions for drying, and then these tests were performed in a soil layer. The soil was prepared from a slurry state and was drying controlling the temperature, the infrared radiation, the wind velocity, and the relative humidity. In the first part of this paper, a description of the climatic chamber, operation ranges and theoretical work principles of the climatic chamber are presented. Then, the second part shows the results for desiccation in water and soil. The desiccation tests performed with the climatic chamber allow simulating all environmental conditions accurately during drying coupling the effect of all environmental variables. As a result, the evaporation rate increases with infrared radiation in soil and water. The rate at the beginning of the desiccation tests in clays is the same as in water. However, this evaporation rate decreases as the soil becomes desiccated.

  17. Integrated climate and hydrology modelling

    DEFF Research Database (Denmark)

    Larsen, Morten Andreas Dahl

    global warming and increased frequency of extreme events. The skill in developing projections of both the present and future climate depends essentially on the ability to numerically simulate the processes of atmospheric circulation, hydrology, energy and ecology. Previous modelling efforts of climate...... and hydrology models to more directly include the interaction between the atmosphere and the land surface. The present PhD study is motivated by an ambition of developing and applying a modelling tool capable of including the interaction and feedback mechanisms between the atmosphere and the land surface...... to the LSM in HIRHAM. A wider range of processes are included at the land surface, subsurface flow is distributed in three dimensions and the temporal and spatial resolution is higher. Secondly, the feedback mechanisms of e.g. soil moisture and recipitation between the two models are included...

  18. An Assessment on the Performance of IPCC AR4 Climate Models in Simulating Interdecadal Variations of the East Asian Summer Monsoon

    Institute of Scientific and Technical Information of China (English)

    SUN Ying; DING Yihui

    2008-01-01

    Observations from several data centers together with a categorization method are used to evaluate the IPCC AR4 (Intergovernmental Panel on Climate Change, the Fourth Assessment Report) climate models' performance in simulating the interdecadal variations of summer precipitation and monsoon circulation in East Asia. Out of 19 models under examination, 9 models can relatively well reproduce the 1979-1999 mean June-July-August (JJA) precipitation in East Asia, but only 3 models (Category-1 models) can capture the interdecadal variation of precipitation in East Asia. These 3 models are: GFDL-CM2.0, MIROC3.2 (hires), and MIROC3.2 (medres), among which the GFDL-CM2.0 gives the best performance. The reason for the poor performance of most models in simulating the East Asian summer monsoon interdecadal variation lies in that the key dynamic and thermal-dynamic mechanisms behind the East Asian monsoon change are missed by the models, e.g., the large-scale tropospheric cooling and drying over East Asia. In contrast, the Category-1 models relatively well reproduce the variations in vertical velocity and water vapor over East Asia and thus show a better agreement with observations in simulating the pattern of "wet south and dry north" in China in the past 20 years.It is assessed that a single model's performance in simulating a particular variable has great impacts on the ensemble results. More realistic outputs can be obtained when the multi-model ensemble is carried out using a suite of well-performing models for a specific variable, rather than using all available models. This indicates that although a multi-model ensemble is in general better than a single model, the best ensemble mean cannot be achieved without looking into each member model's performance.

  19. Climate envelope modeling and dispersal simulations show little risk of range extension of the Shipworm, Teredo navalis (L., in the Baltic sea.

    Directory of Open Access Journals (Sweden)

    Christin Appelqvist

    Full Text Available The shipworm, Teredo navalis, is absent from most of the Baltic Sea. In the last 20 years, increased frequency of T. navalis has been reported along the southern Baltic Sea coasts of Denmark, Germany, and Sweden, indicating possible range-extensions into previously unoccupied areas. We evaluated the effects of historical and projected near-future changes in salinity, temperature, and oxygen on the risk of spread of T. navalis in the Baltic. Specifically, we developed a simple, GIS-based, mechanistic climate envelope model to predict the spatial distribution of favourable conditions for adult reproduction and larval metamorphosis of T. navalis, based on published environmental tolerances to these factors. In addition, we used a high-resolution three-dimensional hydrographic model to simulate the probability of spread of T. navalis larvae within the study area. Climate envelope modeling showed that projected near-future climate change is not likely to change the overall distribution of T. navalis in the region, but will prolong the breeding season and increase the risk of shipworm establishment at the margins of the current range. Dispersal simulations indicated that the majority of larvae were philopatric, but those that spread over a wider area typically spread to areas unfavourable for their survival. Overall, therefore, we found no substantive evidence for climate-change related shifts in the distribution of T. navalis in the Baltic Sea, and no evidence for increased risk of spread in the near-future.

  20. Apparent limitations in the ability of CMIP5 climate models to simulate recent multi-decadal change in surface temperature: implications for global temperature projections

    Science.gov (United States)

    Power, Scott; Delage, François; Wang, Guomin; Smith, Ian; Kociuba, Greg

    2016-09-01

    Observed surface temperature trends over the period 1998-2012/2014 have attracted a great deal of interest because of an apparent slowdown in the rate of global warming, and contrasts between climate model simulations and observations of such trends. Many studies have addressed the statistical significance of these relatively short-trends, whether they indicate a possible bias in the model values and the implications for global warming generally. Here we re-examine these issues, but as they relate to changes over much longer-term changes. We find that on multi-decadal time scales there is little evidence for any change in the observed global warming rate, but some evidence for a recent temporary slowdown in the warming rate in the Pacific. This multi-decadal slowdown can be partly explained by a cool phase of the Interdecadal Pacific Oscillation and a short-term excess of La Niña events. We also analyse historical and projected changes in 38 CMIP climate models. All of the model simulations examined simulate multi-decadal warming in the Pacific over the past half-century that exceeds observed values. This difference cannot be fully explained by observed internal multi-decadal climate variability, even if allowance is made for an apparent tendency for models to underestimate internal multi-decadal variability in the Pacific. Models which simulate the greatest global warming over the past half-century also project warming that is among the highest of all models by the end of the twenty-first century, under both low and high greenhouse gas emission scenarios. Given that the same models are poorest in representing observed multi-decadal temperature change, confidence in the highest projections is reduced.

  1. Simulating the climatic mass balance of Svalbard glaciers from 2003 to 2013 with a high-resolution coupled atmosphere-glacier model

    Directory of Open Access Journals (Sweden)

    K. S. Aas

    2015-10-01

    Full Text Available In this study we simulate the climatic mass balance of Svalbard glaciers with a coupled atmosphere-glacier model with 3 km grid spacing, from September 2003 to September 2013. We find a mean specific net mass balance of −167 mm w.e. yr−1, corresponding to a mean annual mass loss of about 5.7 Gt, with large interannual variability. Our results are compared with a comprehensive set of mass balance, meteorological and satellite measurements. Model temperature biases of 0.17 and −1.9 °C are found at two glacier automatic weather station sites. Simulated climatic mass balance is mostly within about 0.1 m w.e. yr−1 of stake measurements, and simulated winter accumulation at the Austfonna ice cap shows mean absolute errors of 0.05 and 0.06 m w.e. yr−1 when compared to radar-derived values for the selected years 2004 and 2006. Comparison of surface height changes from 2003 to 2008 from model, and satellite altimetry reveals good agreement in both mean values and regional differences. The largest deviations from observations are found for winter accumulation at Hansbreen (up to around 1 m w.e. yr−1, a site where sub-grid topography and wind redistribution of snow are important factors. Comparison with simulations using a 9 km grid spacing reveal considerable differences on regional and local scales. In addition, the 3 km grid spacing allows for a much more detailed comparison with observations than what is possible with a 9 km grid spacing. Further decreasing the grid spacing to 1 km appears to be less significant, although in general precipitation amounts increase with resolution. Altogether, the model compares well with observations and offers possibilities for studying glacier climatic mass balance on Svalbard both historically as well as based on climate projections.

  2. Snow cover and permafrost evolution in Siberia as simulated by the MGO regional climate model in the 20th and 21st centuries

    Science.gov (United States)

    Shkolnik, I. M.; Nadyozhina, E. D.; Pavlova, T. V.; Molkentin, E. K.; Semioshina, A. A.

    2010-01-01

    An approach to ground thermodynamics description using a coupled system of atmospheric regional climate and ground heat transfer models is improved by accounting for the time varying snow density. The simulations are compared to available observational analyses, and the sensitivity of the ground thermal regime to variable snow density is analysed. Projected changes of the ground thermal regime in the 21st century relative to the late 20th century are shown and compared to earlier estimates.

  3. The effect of climate change on the population of sycamore lace bug (Corythuca ciliata, Say) based on a simulation model with phenological response

    OpenAIRE

    2006-01-01

    Climate change affects on insect populations in many ways: it can cause a shift in geographical spread, abundance, or diversity, it can change the location, the timing and the magnitude of outbreaks of pests and it can define the phenological or even the genetic properties of the species. Long-time investigations of special insect populations, simulation models and scenario studies give us very important information about the response of the insects far away and near to our century. Gettin...

  4. White book Escrime. Climatic simulation studies; Livre blanc Escrime. Etude des simulations climatiques

    Energy Technology Data Exchange (ETDEWEB)

    Terray, L. [CERFACS, 31 - Toulouse (France); Braconnot, P. [Institut Pierre-Simon Laplace IPSL/LSCE, CEA-Orme des Merisiers, 91 - Gif-sur-Yvette (France)

    2007-01-15

    The ESCRIME project aims to manage the analysis realized on the climatic simulations on the framework of the fourth report of the GIEC (group of intergovernmental experts on the climate evolution), in particularly the simulations based on french models. This white book is constituted by 8 chapters: the global scenario, the climatic sensibility, the variation modes, the regionalization and the extremes, the hydrological cycle, the polar regions and the cryo-sphere, the carbon cycle, detection and attributions. (A.L.B.)

  5. Modelling Interglacial Climate

    DEFF Research Database (Denmark)

    Pedersen, Rasmus Anker

    , with maximum warming occurring in winter. The three scenarios all affect the climate beyond the Arctic, especially the mid-latitude circulation which is sensitive to the location of the ice loss. Together, the results presented in this thesis illustrate that the changes in the Arctic sea ice cover......, while the insolation appears to be the dominant cause of the expected ice sheet reduction. The second part explores the atmospheric sensitivity to the location of sea ice loss. Three investigated sea ice scenarios with ice loss in different regions all exhibit substantial near-surface warming...... involves some of the same mechanisms in the two climate states. This thesis aims to investigate these mechanisms through climate model experiments. This two-part study has a special focus on the Arctic region, and the main paleoclimate experiments are supplemented by idealized experiments detailing...

  6. Solar irradiance reduction to counteract radiative forcing from a quadrupling of CO2: climate responses simulated by four earth system models

    Directory of Open Access Journals (Sweden)

    M. Lawrence

    2012-06-01

    Full Text Available In this study we compare the response of four state-of-the-art Earth system models to climate engineering under scenario G1 of two model intercomparison projects: GeoMIP (Geoengineering Model Intercomparison Project and IMPLICC (EU project "Implications and risks of engineering solar radiation to limit climate change". In G1, the radiative forcing from an instantaneous quadrupling of the CO2 concentration, starting from the preindustrial level, is balanced by a reduction of the solar constant. Model responses to the two counteracting forcings in G1 are compared to the preindustrial climate in terms of global means and regional patterns and their robustness. While the global mean surface air temperature in G1 remains almost unchanged compared to the control simulation, the meridional temperature gradient is reduced in all models. Another robust response is the global reduction of precipitation with strong effects in particular over North and South America and northern Eurasia. In comparison to the climate response to a quadrupling of CO2 alone, the temperature responses are small in experiment G1. Precipitation responses are, however, in many regions of comparable magnitude but globally of opposite sign.

  7. Advance in Application of Regional Climate Models in China

    Institute of Scientific and Technical Information of China (English)

    ZHANG Wei; YAN Minhua; CHEN Panqin; XU Helan

    2008-01-01

    Regional climate models have become the powerful tools for simulating regional climate and its changeprocess and have been widely used in China. Using regional climate models, some research results have been obtainedon the following aspects: 1) the numerical simulation of East Asian monsoon climate, including exceptional monsoonprecipitation, summer precipitation distribution, East Asian circulation, multi-year climate average condition, summerrain belt and so on; 2) the simulation of arid climate of the western China, including thermal effect of the Qing-hai-Tibet Plateau, the plateau precipitation in the Qilian Mountains; and the impacts of greenhouse effects (CO2 dou-bling) upon climate in the western China; and 3) the simulation of the climate effect of underlying surface changes, in-cluding the effect of soil on climate formation, the influence of terrain on precipitation, the effect of regional soil deg-radation on regional climate, the effect of various underlying surfaces on regional climate, the effect of land-sea con-trast on the climate formulation, the influence of snow cover over the plateau regions on the regional climate, the effectof vegetation changes on the regional climate, etc. In the process of application of regional climate models, the prefer-ences of the models are improved so that better simulation results are gotten. At last, some suggestions are made aboutthe application of regional climate models in regional climate research in the future.

  8. Using records from submarine, aircraft and satellite to evaluate climate model simulations of Arctic sea ice thickness

    Directory of Open Access Journals (Sweden)

    J. Stroeve

    2014-04-01

    Full Text Available Arctic sea ice thickness distributions from models participating in the World Climate Research Programme Coupled Model Intercomparison Project Phase 5 are evaluated against observations from submarines, aircraft and satellites. While it's encouraging that the mean thickness distributions from the models are in general agreement with observations, the spatial patterns of sea ice thickness are poorly represented in most models. The poor spatial representation of thickness patterns is associated with a failure of models to represent details of the mean atmospheric circulation pattern that governs the transport and spatial distribution of sea ice. The climate models as a whole also tend to underestimate the rate of ice volume loss from 1979 to 2013, though the multi-model ensemble mean trend remains within the uncertainty of that from the Pan-Arctic Ice Ocean Modeling and Assimilation System. These results raise concerns regarding the ability of CMIP5 models to realistically represent the processes driving the decline of Arctic sea ice and project the timing of when a seasonally ice-free Arctic may be realized.

  9. Simulation Modeling of Lakes in Undergraduate and Graduate Classrooms Increases Comprehension of Climate Change Concepts and Experience with Computational Tools

    Science.gov (United States)

    Carey, Cayelan C.; Gougis, Rebekka Darner

    2017-01-01

    Ecosystem modeling is a critically important tool for environmental scientists, yet is rarely taught in undergraduate and graduate classrooms. To address this gap, we developed a teaching module that exposes students to a suite of modeling skills and tools (including computer programming, numerical simulation modeling, and distributed computing)…

  10. MODFLOW datasets for simulations of groundwater flow with downscaled global climate model data for the Suwannee River Basin, Florida

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — A previously-developed groundwater model of the Suwannee River Basin was modified and calibrated to represent transient conditions. A simulation of recent conditions...

  11. Simulation and Analysis of China Climate Using Two-Way Interactive Atmosphere-Vegetation Model (RIEMS-AVIM)

    Institute of Scientific and Technical Information of China (English)

    GAO Rong; DONG Wenjie; WEI Zhigang

    2008-01-01

    In this paper, an Atmosphere-Vegetation Interaction Model (AVIM) is coupled to the Regional Integrated Environment Model System (RIEMS), and a 10-year integration for China is performed using the RIEMS-AVIM. The analysis of the results of the 10-year integration shows that the characters of the spatial distributions of temperature and precipitation over China are well simulated. The patterns of simulated surface sensible and latent heat fluxes match well with the spatial climatological atlas: the values of winter surface sensible and latent heat fluxes are both lower than climatological values over the whole country. Summer surface sensible heat flux is higher than climatological values in western China and lower in eastern China, while summer surface latent heat flux is higher than climatological values in the eastern and lower in the western. Seasonal variations of simulated temperature and precipitation of RIMES-AVIM agree with those of the observed. Simulated temperature is lower than the observed in the Tibetan Plateau and North-west China for the whole year, slightly lower in the remaining regions in winter, but consistent with the observed in summer. The simulated temperature of RIEMS-AVIM is higher in winter and lower in summer than that of RIEMS, which shows that the simulated tempcrature of RIEMS-AVIM is closer to the observed value. Simulated precipitation is excessive in the first half of the year, but consistent with the observed in the second half of the year. The simulated summer precipitation of RIEMS-AVIM has significant improvement compared to that of RIEMS, which is less and closer to the observed value. The interannual variations of temperature and precipitation are also fairly well simulated, with temperature simulation being superior to precipitation simulation. The interannual variation of simulated temperature is significantly correlated with the observed in Northeast China, the Transition Region, South China, and the Tibetan Plateau, but

  12. Changes in Extreme Events as Simulated by a High-Resolution Regional Climate Model for the Next 20-30 Years over China

    Institute of Scientific and Technical Information of China (English)

    XU Ji-Yun; SHI Ying; GAO Xue-Jie

    2012-01-01

    In this paper, the changes in temperature and precipitation extremes over the next 20-30 years (2021-2050) in relative to the present day (1986-2005) under the Intergovernmental Panel on Climate Change (IPCC) Special Report on Emissions Scenarios (SRES) A1B scenario are analyzed based on a high-resolution climate change simulation performed by a regional climate model (the Abdus Salam International Center for Theoretical Physics (ICTP) RegCM3). The extreme indices of summer days (SU), frost days (FD), and growing season length (GSL) for temperature and simple daily intensity index (SDII), number of days with precipitation ≥10 mm d-1 (R10), and consecutive dry days (CDD) for precipitation are used as the indicators of the extremes. The results show that the indices simulated by RegCM3 in the present day show good agreement with the observed. A general increase in SU, a decrease in FD, and an increase in GSL are found to occur in the next 20-30 years over China. A general increase in SDII, an increase in R10 over western China, and a decrease in R10 in north, northeast, and central China are simulated by the model. Changes in CDD are characterized by a decrease in the north and an increase in the south and the Tibetan Plateau.

  13. Evaluation Case Studies and Intercomparison with Regional Climate Model Simulations based on the DUE PERMAFROST Circumpolar Remote Sensing Service for Permafrost

    Science.gov (United States)

    Heim, Birgit; Bartsch, Annett; Elger, Kirsten; Rinke, Annette; Matthes, Heidrun; Zhou, Xu; Klehmet, Katharina; Buchhorn, Marcel; Duguay, Claude

    2014-05-01

    Permafrost is a subsurface phenomenon. However, monitoring from Earth Observation (EO) platforms can provide spatio-temporal data sets on permafrost-related indicators and geophysical parameters used in modelling and monitoring. The ESA Data User Element (DUE) Permafrost project (2009-2012) developed a suite of EO satellite-derived products: Land Surface Temperature (LST), Surface Soil Moisture (SSM), Surface Frozen and Thawed State (Freeze/Thaw), Terrain, Land Cover, and Surface Water. The satellite-derived products are weekly and monthly averages of the bio- and geophysical terrestrial parameters and static circum-Arctic maps. The final DUE Permafrost products cover the years 2007 to 2011 with a circum-Arctic coverage (north of 50°N). The products were released in 2012, and updated in 2013. Further information is available at geo.tuwien.ac.at/permafrost/. The remote sensing service also supports the EU-FP7 funded project PAGE21 - Changing Permafrost in the Arctic and its Global Effects in the 21st Century (www.page21.eu). The Global Terrestrial Network for Permafrost (GTN-P), initiated by the International Permafrost Association (IPA), is the prime program concerned with monitoring of permafrost. It provides an important database for the evaluation of EO-derived products and climate and permafrost models. GTN-P ground data ranges from air-, ground-, and borehole temperature data to active layer monitoring, soil moisture measurements, and the description of landform and vegetation. The involvement of scientific stakeholders and the IPA, and the ongoing evaluation of the satellite-derived products make the DUE Permafrost products relevant to the scientific community. The Helmholtz Climate Initiative REKLIM (Regionale KlimaAnderungen/Regional Climate Change) is a climate research program where regional observations and process studies are coupled with model simulations (http://www.reklim.de/en/home/). ESA DUE Permafrost User workshops initiated the use of EO

  14. ESA Data User Element DUE PERMAFROST Circumpolar Remote Sensing Service for Permafrost - Evaluation Case Studies and Intercomparison with Regional Climate Model Simulations

    Science.gov (United States)

    Heim, Birgit; Bartsch, Annett; Elger, Kirsten; Rinke, Annette; Matthes, Heidrun; Zhou, Xu; Klehmet, Katharina; Rockel, Burkhardt; Lantuit, Hugues; Duguay, Claude

    2015-04-01

    Permafrost is a subsurface phenomenon. However, monitoring from Earth Observation (EO) platforms can provide spatio-temporal data sets on permafrost-related indicators and quantities used in modelling and monitoring. The ESA Data User Element (DUE) Permafrost project (2009-2012) developed a suite of EO satellite-derived products: Land Surface Temperature (LST), Surface Soil Moisture (SSM), Surface Frozen and Thawed State (Freeze/Thaw), Terrain, Land Cover, and Surface Water. The satellite-derived products are weekly and monthly averages of the bio- and geophysical terrestrial parameters and static circum-Arctic maps. The final DUE Permafrost products cover the years 2007 to 2011, some products up to 2013, with a circum-Arctic coverage (north of 50°N). The products were released in 2012, and updated in 2013 and 2014. Further information is available at geo.tuwien.ac.at/permafrost/. The remote sensing service also supports the EU-FP7 funded project PAGE21 - Changing Permafrost in the Arctic and its Global Effects in the 21st Century (www.page21.eu). The Global Terrestrial Network for Permafrost (GTN-P), initiated by the International Permafrost Association (IPA), is the prime program concerned with monitoring of permafrost. It provides an important database for the evaluation of EO-derived products and climate and permafrost models. GTN-P ground data ranges from air-, ground-, and borehole temperature data to active layer monitoring, soil moisture measurements, and the description of landform and vegetation. The involvement of scientific stakeholders and the IPA, and the ongoing evaluation of the satellite-derived products make the DUE Permafrost products relevant to the scientific community. The Helmholtz Climate Initiative REKLIM (Regionale KlimaAnderungen/Regional Climate Change) is a climate research program where regional observations and process studies are coupled with model simulations (http://www.reklim.de/en/home/). ESA DUE Permafrost User workshops

  15. Simulating Crop Net Primary Production in China from 2000 to 2050 by Linking the Crop-C model with a FGOALS's Model Climate Change Scenario

    Institute of Scientific and Technical Information of China (English)

    ZHANG Wen; HUANG Yao; SUN Wenjuan; YU Yongqiang

    2007-01-01

    Net primary production (NPP) of crop represents the capacity of sequestrating atmospheric CO2 in agro-ecosystem, and it plays an important role in terrestrial carbon cycling. By linking the Crop-C model with climate change scenario projected by a coupled GCM FGOALS via geographical information system(GIS) techniques, crop NPP in China was simulated from 2000 to 2050. The national averaged surface air temperature from FGOALS is projected to increase by 1.0°C over this period and the corresponding atmospheric CO2 concentration is 535 ppm by 2050 under the IPCC A1B scenario. With a spatial resolution of 10 × 10 km2, model simulation indicated that an annual average increase of 0.6 Tg C yr-1 (Tg=1012g)would be possible under the A1B scenario. The NPP in the late 2040s would increase by 5% (30 Tg C)within the 98×106 hm2 cropland area in contrast with that in the early 2000s. A further investigation suggested that changes in the NPP would not be evenly distributed in China. A higher increase would occur in a majority of regions located in eastern and northwestern China, while a slight reduction would appear in Hebei and Tianjin in northern China. The spatial characteristics of the crop NPP change are attributed primarily to the uneven distribution of temperature change.

  16. Improvements in precipitation simulation over South America for past and future climates via multi-model combination

    Science.gov (United States)

    Coutinho, Maytê Duarte Leal; Lima, Kellen Carla; Santos e Silva, Cláudio Moisés

    2016-09-01

    Combining individual forecasts is one of the practices used to improve weather prediction results. Identifying which combination of techniques results in a more accurate forecast is the subject of many comparative studies as well proposals for combined methods. Here we compare three combination techniques: (1) principal component regression (PCR), (2) convex combination by mean squared errors (MSE) and (3) ensemble average to combine six regional climate models of the Regional Climate Change Assessment for the La Plata Basin Project (CLARIS-LPB) for variable rainfall in three regions: Amazon (AMZ), Northeastern Brazil (NEB) and La Plata Basin (LPB), for the past (1961-1990) and future (2071-2100) climates. The results indicate that the average RMSE values showed improved representation of climate for LPB in some months, which is an important advance in climate studies. On the other hand, PCR presented greater accuracy (lower RMSE) than MSE in the AMZ and NEB regions. In winter months, both combinations presented lower RMSE results, mainly PCR in the three study regions. The correlation coefficient supports the results already found, namely, PCR obtained moderate to strong correlations, which were statistically significant at 5 % in both regions for all months, while MSE presented low to moderate correlations, which were statically significant at 5 % only in some months. Based on that, PCR achieved the best corrected forecast, as it was superior in forecasting precipitation due to the lower RMSE value. It is noteworthy that the PCR data were first subjected to principal component analysis (PCA) and the scores were used to perform the prediction.

  17. Impact of CO2-Induced Warming on Simulated Hurricane Intensity and Precipitation: Sensitivity to the Choice of Climate Model and Convective Parameterization.

    Science.gov (United States)

    Knutson, Thomas R.; Tuleya, Robert E.

    2004-09-01

    Previous studies have found that idealized hurricanes, simulated under warmer, high-CO2 conditions, are more intense and have higher precipitation rates than under present-day conditions. The present study explores the sensitivity of this result to the choice of climate model used to define the CO2-warmed environment and to the choice of convective parameterization used in the nested regional model that simulates the hurricanes. Approximately 1300 five-day idealized simulations are performed using a higher-resolution version of the GFDL hurricane prediction system (grid spacing as fine as 9 km, with 42 levels). All storms were embedded in a uniform 5 m s-1 easterly background flow. The large-scale thermodynamic boundary conditions for the experiments— atmospheric temperature and moisture profiles and SSTs—are derived from nine different Coupled Model Intercomparison Project (CMIP2+) climate models. The CO2-induced SST changes from the global climate models, based on 80-yr linear trends from +1% yr-1 CO2 increase experiments, range from about +0.8° to +2.4°C in the three tropical storm basins studied. Four different moist convection parameterizations are tested in the hurricane model, including the use of no convective parameterization in the highest resolution inner grid. Nearly all combinations of climate model boundary conditions and hurricane model convection schemes show a CO2-induced increase in both storm intensity and near-storm precipitation rates. The aggregate results, averaged across all experiments, indicate a 14% increase in central pressure fall, a 6% increase in maximum surface wind speed, and an 18% increase in average precipitation rate within 100 km of the storm center. The fractional change in precipitation is more sensitive to the choice of convective parameterization than is the fractional change of intensity. Current hurricane potential intensity theories, applied to the climate model environments, yield an average increase of intensity

  18. Interannual-to-decadal variability of the stratosphere during the 20th century: ensemble simulations with a chemistry-climate model

    Directory of Open Access Journals (Sweden)

    A. M. Fischer

    2008-07-01

    Full Text Available Interannual-to-decadal variability in stratospheric ozone and climate have a number of common sources, such as variations in solar irradiance, stratospheric aerosol loading due to volcanic eruptions, El Niño Southern Oscillation variability and the quasi-biennial oscillation (QBO. Currently available data records as well as model simulations addressing stratospheric chemical climate variability mostly cover only the past few decades, which is often insufficient to address natural interannual-to-decadal variability. Here we make use of recently reconstructed and re-evaluated data products to force and validate transient ensemble model simulations (nine members across the twentieth century computed by means of the chemistry-climate model SOCOL. The forcings included sea surface temperatures, sea ice, solar irradiance, stratospheric aerosols, QBO, changes in land properties, greenhouse gases, ozone depleting substances, and emissions of carbon monoxides, and nitrogen oxides. The transient simulations are in good agreement with observations, reconstructions and reanalyses and allow quantification of interannual-to-decadal variability during the 20th century. All ensemble members are able to capture the low-frequency variability in tropical and mid-latitudinal total ozone as well as in the strength of the subtropical jet, suggesting a realistic response to external forcings in this area. The region of the northern polar vortex exhibits a large internal model variability that is found in the frequency, seasonality, and strength of major warmings as well as in the strength of the modeled polar vortex. Results from process-oriented analysis, such as correlation between the vertical Eliassen Palm flux (EP flux component and polar variables as well as stratospheric ozone trends, are of comparable magnitude to those observed and are consistent in all analysed ensemble members. Yet, trend estimates of the vertical EP flux component vary greatly among

  19. Climate warming due to increasing atmospheric CO2 - Simulations with a multilayer coupled atmosphere-ocean seasonal energy balance model

    Science.gov (United States)

    Li, Peng; Chou, Ming-Dah; Arking, Albert

    1987-01-01

    The transient response of the climate to increasing CO2 is studied using a modified version of the multilayer energy balance model of Peng et al. (1982). The main characteristics of the model are described. Latitudinal and seasonal distributions of planetary albedo, latitude-time distributions of zonal mean temperatures, and latitudinal distributions of evaporation, water vapor transport, and snow cover generated from the model and derived from actual observations are analyzed and compared. It is observed that in response to an atmospheric doubling of CO2, the model reaches within 1/e of the equilibrium response of global mean surface temperature in 9-35 years for the probable range of vertical heat diffusivity in the ocean. For CO2 increases projected by the National Research Council (1983), the model's transient response in annually and globally averaged surface temperatures is 60-75 percent of the corresponding equilibrium response, and the disequilibrium increases with increasing heat diffusivity of the ocean.

  20. Validation of two high‐resolution climate simulations over Scandinavia

    DEFF Research Database (Denmark)

    Mayer, Stephanie; Maule, Cathrine Fox; Sobolowski, Stefan

    2014-01-01

    Before running climate projections with numerical models it is important to validate their performance under present climate conditions. Within the RiskChange project two high‐resolution regional climate models were run as a perfect boundary experiment over Scandinavia. The simulations are valida......Before running climate projections with numerical models it is important to validate their performance under present climate conditions. Within the RiskChange project two high‐resolution regional climate models were run as a perfect boundary experiment over Scandinavia. The simulations...... are validated with respect to timing, location and intensity of extreme events. The main objective of the RiskChange project (www.riskchange.dhigroup.com) is to establish a consistent scientifically‐based framework for risk‐based design using state‐of‐the‐art knowledge of future changes in climate extreme...... statistics. Very high resolution is required in impact models that are employed to address particular societal needs and risks in terms of adaptation to future climate challenges, (e.g. future storm surge protection of coastlines and low‐level lands or drainage systems in urban areas). The purpose...

  1. The importance of equilibration in glacial climate simulations

    Science.gov (United States)

    Brandefelt, Jenny; Kjellström, Erik; Näslund, Jens-Ove; Strandberg, Gustav; Voelker, Antje; Wohlfarth, Barbara

    2010-05-01

    Last Glacial Maximum (21 000 yrs BP; LGM) and Greenland Stadial 12 (44 000 yrs BP; GS12) climate has been simulated with the National Centre for Atmospheric Research (NCAR) Community Climate System Model version 3 (CCSM3). Although the simulations were initiated from simulated glacial climates, both simulations required 1500 years of additional integration to reach equilibrium under the imposed boundary conditions and forcings. The annual global mean surface temperature changes by only 0.1oC during the last 1000 years of the 1500 year long GS12 simulation. Despite this small global change the slow equilibration is important for the simulated regional climate. The corresponding change in the annual mean surface air temperature in the North Atlantic region is more than 3oC with a maximum of 8oC in south-eastern Greenland. This regional change is coupled to a decrease of the sea ice extent in the North Atlantic region. Both climates are compared to available proxy data of sea surface temperature (SST). The simulated SST changes by up to 2oC in the North Atlantic region during the last 1000 years of the GS12 integration which leads to a better agreement with proxy data. Simulated LGM SSTs are colder than the proxy data but show similar spatial patterns. Simulated GS12 SSTs are in better agreement with the available proxy data.

  2. Narrowing of the Upwelling Branch of the Brewer-Dobson Circulation and Hadley Cell in Chemistry-Climate Model Simulations of the 21st Century

    Science.gov (United States)

    Li, Feng; Stolarski, Richard S.; Pawson, Steven; Newman, Paul A.; Waugh, Darryn

    2010-01-01

    Changes in the width of the upwelling branch of the Brewer-Dobson circulation and Hadley cell in the 21st Century are investigated using simulations from a coupled chemistry-climate model. In these model simulations the tropical upwelling region narrows in the troposphere and lower stratosphere. The narrowing of the Brewer-Dobson circulation is caused by an equatorward shift of Rossby wave critical latitudes and Eliassen-Palm flux convergence in the subtropical lower stratosphere. In the troposphere, the model projects an expansion of the Hadley cell's poleward boundary, but a narrowing of the Hadley cell's rising branch. Model results suggest that eddy forcing may also play a part in the narrowing of the rising branch of the Hadley cell.

  3. Statistical framework for evaluation of climate model simulations by use of climate proxy data from the last millennium – Part 3: Practical considerations, relaxed assumptions, and using tree-ring data to address the amplitude of solar forcing

    Directory of Open Access Journals (Sweden)

    A. Moberg

    2014-06-01

    Full Text Available Practical issues arise when applying a statistical framework for unbiased ranking of alternative forced climate model simulations by comparison with climate observations from instrumental and proxy data (Part 1 in this series. Given a set of model and observational data, several decisions need to be made; e.g. concerning the region that each proxy series represents, the weighting of different regions, and the time resolution to use in the analysis. Objective selection criteria cannot be made here, but we argue to study how sensitive the results are to the choices made. The framework is improved by the relaxation of two assumptions; to allow autocorrelation in the statistical model for simulated climate variability, and to enable direct comparison of alternative simulations to test if any of them fit the observations significantly better. The extended framework is applied to a set of simulations driven with forcings for the pre-industrial period 1000–1849 CE and fifteen tree-ring based temperature proxy series. Simulations run with only one external forcing (land-use, volcanic, small-amplitude solar, or large-amplitude solar, do not significantly capture the variability in the tree-ring data – although the simulation with volcanic forcing does so for some experiment settings. When all forcings are combined (using either the small- or large-amplitude solar forcing including also orbital, greenhouse-gas and non-volcanic aerosol forcing, and additionally used to produce small simulation ensembles starting from slightly different initial ocean conditions, the resulting simulations are highly capable of capturing some observed variability. Nevertheless, for some choices in the experiment design, they are not significantly closer to the observations than when unforced simulations are used, due to highly variable results between regions. It is also not possible to tell whether the small-amplitude or large-amplitude solar forcing causes the multiple

  4. Westerly jet stream and past millennium climate change in Arid Central Asia simulated by COSMO-CLM model

    Science.gov (United States)

    Fallah, Bijan; Sodoudi, Sahar; Cubasch, Ulrich

    2016-05-01

    This study tackles one of the most debated questions around the evolution of Central Asian climate: the "Puzzle" of moisture changes in Arid Central Asia (ACA) throughout the past millennium. A state-of-the-art Regional Climate Model (RCM) is subsequently employed to investigate four different 31-year time slices of extreme dry and wet spells, chosen according to changes in the driving data, in order to analyse the spatio-temporal evolution of the moisture variability in two different climatological epochs: Medieval Climate Anomaly (MCA) and Little Ice Age (LIA). There is a clear regime behavior and bimodality in the westerly Jet phase space throughout the past millennium in ACA. The results indicate that the regime changes during LIA show a moist ACA and a dry East China. During the MCA, the Kazakhstan region shows a stronger response to the westerly jet equatorward shift than during the LIA. The out-of-phase pattern of moisture changes between India and ACA exists during both the LIA and the MCA. However, the pattern is more pronounced during the LIA.

  5. Regional Climate Model Intercomparison Project for Asia.

    Science.gov (United States)

    Fu, Congbin; Wang, Shuyu; Xiong, Zhe; Gutowski, William J.; Lee, Dong-Kyou; McGregor, John L.; Sato, Yasuo; Kato, Hisashi; Kim, Jeong-Woo; Suh, Myoung-Seok

    2005-02-01

    Improving the simulation of regional climate change is one of the high-priority areas of climate study because regional information is needed for climate change impact assessments. Such information is especially important for the region covered by the East Asian monsoon where there is high variability in both space and time. To this end, the Regional Climate Model Intercomparison Project (RMIP) for Asia has been established to evaluate and improve regional climate model (RCM) simulations of the monsoon climate. RMIP operates under joint support of the Asia-Pacific Network for Global Change Research (APN), the Global Change System for Analysis, Research and Training (START), the Chinese Academy of Sciences, and several projects of participating nations. The project currently involves 10 research groups from Australia, China, Japan, South Korea, and the United States, as well as scientists from India, Italy, Mongolia, North Korea, and Russia.RMIP has three simulation phases: March 1997-August 1998, which covers a full annual cycle and extremes in monsoon behavior; January 1989-December 1998, which examines simulated climatology; and a regional climate change scenario, involving nesting with a global model. This paper is a brief report of RMIP goals, implementation design, and some initial results from the first phase studies.

  6. A model for simulating the response of runoff from the mountainous watersheds of inland river basins in the arid area of northwest China to climatic changes

    Institute of Scientific and Technical Information of China (English)

    康尔泗; 程国栋; 蓝永超; 金会军

    1999-01-01

    A model for simulating the response of monthly runoff from the mountainous watersheds to climatic changes is developed.The model is based on the modifications to the HBV runoff model, and therefore represents the characteristics and runoff generation processes of inland river basins in the arid area of northwest China. Taking the mountainous watershed of an inland river, the Heihe River originating from the Qilian Mountains and running through the Hexi Corridor as an example, the monthly runoff changes under different climate scenarios are simulated. The simulation indicates that, during the years from 1994 to 2030, if the annual mean air temperature increases by 0.5℃, and precipitation keeps unchanged, then the runoff of May and October will increase because of the increase of the snow melt runoff, but the runoff of July and August will decrease to some extent because of the increase of evaporation, and as a result, the annual runoff will decrease by 4%. If the precipitation still keeps unchanged, an

  7. Towards Cloud-Resolving European-Scale Climate Simulations using a fully GPU-enabled Prototype of the COSMO Regional Model

    Science.gov (United States)

    Leutwyler, David; Fuhrer, Oliver; Cumming, Benjamin; Lapillonne, Xavier; Gysi, Tobias; Lüthi, Daniel; Osuna, Carlos; Schär, Christoph

    2014-05-01

    The representation of moist convection is a major shortcoming of current global and regional climate models. State-of-the-art global models usually operate at grid spacings of 10-300 km, and therefore cannot fully resolve the relevant upscale and downscale energy cascades. Therefore parametrization of the relevant sub-grid scale processes is required. Several studies have shown that this approach entails major uncertainties for precipitation processes, which raises concerns about the model's ability to represent precipitation statistics and associated feedback processes, as well as their sensitivities to large-scale conditions. Further refining the model resolution to the kilometer scale allows representing these processes much closer to first principles and thus should yield an improved representation of the water cycle including the drivers of extreme events. Although cloud-resolving simulations are very useful tools for climate simulations and numerical weather prediction, their high horizontal resolution and consequently the small time steps needed, challenge current supercomputers to model large domains and long time scales. The recent innovations in the domain of hybrid supercomputers have led to mixed node designs with a conventional CPU and an accelerator such as a graphics processing unit (GPU). GPUs relax the necessity for cache coherency and complex memory hierarchies, but have a larger system memory-bandwidth. This is highly beneficial for low compute intensity codes such as atmospheric stencil-based models. However, to efficiently exploit these hybrid architectures, climate models need to be ported and/or redesigned. Within the framework of the Swiss High Performance High Productivity Computing initiative (HP2C) a project to port the COSMO model to hybrid architectures has recently come to and end. The product of these efforts is a version of COSMO with an improved performance on traditional x86-based clusters as well as hybrid architectures with GPUs

  8. A new framework for quantifying uncertainties in modelling studies for future climates - how more certain are CMIP5 precipitation and temperature simulations compared to CMIP3?

    Science.gov (United States)

    Sharma, A.; Woldemeskel, F. M.; Sivakumar, B.; Mehrotra, R.

    2014-12-01

    We outline a new framework for assessing uncertainties in model simulations, be they hydro-ecological simulations for known scenarios, or climate simulations for assumed scenarios representing the future. This framework is illustrated here using GCM projections for future climates for hydrologically relevant variables (precipitation and temperature), with the uncertainty segregated into three dominant components - model uncertainty, scenario uncertainty (representing greenhouse gas emission scenarios), and ensemble uncertainty (representing uncertain initial conditions and states). A novel uncertainty metric, the Square Root Error Variance (SREV), is used to quantify the uncertainties involved. The SREV requires: (1) Interpolating raw and corrected GCM outputs to a common grid; (2) Converting these to percentiles; (3) Estimating SREV for model, scenario, initial condition and total uncertainty at each percentile; and (4) Transforming SREV to a time series. The outcome is a spatially varying series of SREVs associated with each model that can be used to assess how uncertain the system is at each simulated point or time. This framework, while illustrated in a climate change context, is completely applicable for assessment of uncertainties any modelling framework may be subject to. The proposed method is applied to monthly precipitation and temperature from 6 CMIP3 and 13 CMIP5 GCMs across the world. For CMIP3, B1, A1B and A2 scenarios whereas for CMIP5, RCP2.6, RCP4.5 and RCP8.5 representing low, medium and high emissions are considered. For both CMIP3 and CMIP5, model structure is the largest source of uncertainty, which reduces significantly after correcting for biases. Scenario uncertainly increases, especially for temperature, in future due to divergence of the three emission scenarios analysed. While CMIP5 precipitation simulations exhibit a small reduction in total uncertainty over CMIP3, there is almost no reduction observed for temperature projections

  9. A comparison of climate simulations for the last glacial maximum with three different versions of the ECHAM model and implications for summer-green tree refugia

    Directory of Open Access Journals (Sweden)

    K. Arpe

    2011-02-01

    Full Text Available Model simulations of the last glacial maximum (21 ± 2 ka with the ECHAM3 T42 atmosphere-only, ECHAM5-MPIOM T31 atmosphere-ocean coupled and ECHAM5 T106 atmosphere-only models are compared. The topography, land-sea mask and glacier distribution for the ECHAM5 simulations were taken from the Paleoclimate Modelling Intercomparison Project Phase II (PMIP2 data set while for ECHAM3 they were taken from PMIP1. The ECHAM5-MPIOM T31 model produced its own sea surface temperatures (SST while the ECHAM5 T106 simulations were forced at the boundaries by this coupled model SSTs corrected from their present-day biases and the ECHAM3 T42 model was forced with prescribed SSTs provided by Climate/Long-Range Investigation, Mapping, and Prediction project (CLIMAP.

    The SSTs in the ECHAM5-MPIOM simulation for the last glacial maximum (LGM were much warmer in the northern Atlantic than those suggested by CLIMAP or Overview of Glacial Atlantic Ocean Mapping (GLAMAP while the SSTs were cooler everywhere else. This had a clear effect on the temperatures over Europe, warmer for winters in western Europe and cooler for eastern Europe than the simulation with CLIMAP SSTs.

    Considerable differences in the general circulation patterns were found in the different simulations. A ridge over western Europe for the present climate during winter in the 500 hPa height field remains in both ECHAM5 simulations for the LGM, more so in the T106 version, while the ECHAM3 CLIMAP-SST simulation provided a trough which is consistent with cooler temperatures over western Europe. The zonal wind between 30° W and 10° E shows a southward shift of the polar and subtropical jets in the simulations for the LGM, least obvious in the ECHAM5 T31 one, and an extremely strong polar jet for the ECHAM3 CLIMAP-SST run. The latter can probably be assigned to the much stronger north-south gradient in the CLIMAP SSTs. The southward shift of the polar jet during the LGM is supported by

  10. The uncertainty of UTCI due to uncertainties in the determination of radiation fluxes derived from numerical weather prediction and regional climate model simulations.

    Science.gov (United States)

    Schreier, Stefan F; Suomi, Irene; Bröde, Peter; Formayer, Herbert; Rieder, Harald E; Nadeem, Imram; Jendritzky, Gerd; Batchvarova, Ekaterina; Weihs, Philipp

    2013-03-01

    In this study we examine the determination accuracy of both the mean radiant temperature (Tmrt) and the Universal Thermal Climate Index (UTCI) within the scope of numerical weather prediction (NWP), and global (GCM) and regional (RCM) climate model simulations. First, Tmrt is determined and the so-called UTCI-Fiala model is then used for the calculation of UTCI. Taking into account the uncertainties of NWP model (among others the HIgh Resolution Limited Area Model HIRLAM) output (temperature, downwelling short-wave and long-wave radiation) stated in the literature, we simulate and discuss the uncertainties of Tmrt and UTCI at three stations in different climatic regions of Europe. The results show that highest negative (positive) differences to reference cases (under assumed clear-sky conditions) of up to -21°C (9°C) for Tmrt and up to -6°C (3.5°C) for UTCI occur in summer (winter) due to cloudiness. In a second step, the uncertainties of RCM simulations are analyzed: three RCMs, namely ALADIN (Aire Limitée Adaptation dynamique Développement InterNational), RegCM (REGional Climate Model) and REMO (REgional MOdel) are nested into GCMs and used for the prediction of temperature and radiation fluxes in order to estimate Tmrt and UTCI. The inter-comparison of RCM output for the three selected locations shows that biases between 0.0 and ±17.7°C (between 0.0 and ±13.3°C) for Tmrt (UTCI), and RMSE between ±0.5 and ±17.8°C (between ±0.8 and ±13.4°C) for Tmrt (UTCI) may be expected. In general the study shows that uncertainties of UTCI, due to uncertainties arising from calculations of radiation fluxes (based on NWP models) required for the prediction of Tmrt, are well below ±2°C for clear-sky cases. However, significant higher uncertainties in UTCI of up to ±6°C are found, especially when prediction of cloudiness is wrong.

  11. High resolution modeling of the upper troposphere and lower stratosphere region over the Arctic - GEM-AC simulations for the future climate with and without aviation emissions.

    Science.gov (United States)

    Porebska, Magdalena; Struzewska, Joanna; Kaminski, Jacek W.

    2016-04-01

    Upper troposphere and lower stratosphere (UTLS) region is a layer around the tropopause. Perturbation of the chemical composition in the UTLS region can impact physical and dynamical processes that can lead to changes in cloudiness, precipitation, radiative forcing, stratosphere-troposphere exchange and zonal flow. The objective of this study is to investigate the potential impacts of aviation emissions on the upper troposphere and lower stratosphere. In order to assess the impact of the aviation emissions we will focus on changes in atmospheric dynamic due to changes in chemical composition in the UTLS over the Arctic. Specifically, we will assess perturbations in the distribution of the wind, temperature and pressure fields in the UTLS region. Our study will be based on simulations using a high resolution chemical weather model for four scenarios of current (2006) and future (2050) climate: with and without aircraft emissions. The tool that we use is the GEM-AC (Global Environmental Multiscale with Atmospheric Chemistry) chemical weather model where air quality, free tropospheric and stratospheric chemistry processes are on-line and interactive in an operational weather forecast model of Environment Canada. In vertical, the model domain is defined on 70 hybrid levels with model top at 0.1 mb. The gas-phase chemistry includes detailed reactions of Ox, NOx, HOx, CO, CH4, ClOx and BrO. Also, the model can address aerosol microphysics and gas-aerosol partitioning. Aircraft emissions are from the AEDT 2006 database developed by the Federal Aviation Administration (USA) and the future climate simulations are based on RCP8.5 projection presented by the IPCC in the fifth Assessment Report AR5. Results from model simulations on a global variable grid with 0.5o x 0.5o uniform resolution over the Arctic will be presented.

  12. The freshwater balance of polar regions in transient simulations from 1500 to 2100 AD using a comprehensive coupled climate model

    Energy Technology Data Exchange (ETDEWEB)

    Lehner, Flavio; Raible, Christoph C.; Hofer, Dominik; Stocker, Thomas F. [University of Bern, Climate and Environmental Physics, Physics Institute, and Oeschger Centre for Climate Change Research, Bern (Switzerland)

    2012-07-15

    The ocean and sea ice in both polar regions are important reservoirs of freshwater within the climate system. While the response of these reservoirs to future climate change has been studied intensively, the sensitivity of the polar freshwater balance to natural forcing variations during preindustrial times has received less attention. Using an ensemble of transient simulations from 1500 to 2100 AD we put present-day and future states of the polar freshwater balance in the context of low frequency variability of the past five centuries. This is done by focusing on different multi-decadal periods of characteristic external forcing. In the Arctic, freshwater is shifted from the ocean to sea ice during the Maunder Minimum while the total amount of freshwater within the Arctic domain remains unchanged. In contrast, the subsequent Dalton Minimum does not leave an imprint on the slow-reacting reservoirs of the ocean and sea ice, but triggers a drop in the import of freshwater through the atmosphere. During the twentieth and twenty-first century the build-up of freshwater in the Arctic Ocean leads to a strengthening of the liquid export. The Arctic freshwater balance is shifted towards being a large source of freshwater to the North Atlantic ocean. The Antarctic freshwater cycle, on the other hand, appears to be insensitive to preindustrial variations in external forcing. In line with the rising temperature during the industrial era the freshwater budget becomes increasingly unbalanced and strengthens the high latitude's Southern Ocean as a source of liquid freshwater to lower latitude oceans. (orig.)

  13. Seasonal cycle of Martian climate : Experimental data and numerical simulation

    NARCIS (Netherlands)

    Rodin, A. V.; Willson, R. J.

    2006-01-01

    The most adequate theoretical method of investigating the present-day Martian climate is numerical simulation based on a model of general circulation of the atmosphere. First and foremost, such models encounter the greatest difficulties in description of aerosols and clouds, which in turn essentiall

  14. Modeling and assessing international climate financing

    Science.gov (United States)

    Wu, Jing; Tang, Lichun; Mohamed, Rayman; Zhu, Qianting; Wang, Zheng

    2016-06-01

    Climate financing is a key issue in current negotiations on climate protection. This study establishes a climate financing model based on a mechanism in which donor countries set up funds for climate financing and recipient countries use the funds exclusively for carbon emission reduction. The burden-sharing principles are based on GDP, historical emissions, and consumptionbased emissions. Using this model, we develop and analyze a series of scenario simulations, including a financing program negotiated at the Cancun Climate Change Conference (2010) and several subsequent programs. Results show that sustained climate financing can help to combat global climate change. However, the Cancun Agreements are projected to result in a reduction of only 0.01°C in global warming by 2100 compared to the scenario without climate financing. Longer-term climate financing programs should be established to achieve more significant benefits. Our model and simulations also show that climate financing has economic benefits for developing countries. Developed countries will suffer a slight GDP loss in the early stages of climate financing, but the longterm economic growth and the eventual benefits of climate mitigation will compensate for this slight loss. Different burden-sharing principles have very similar effects on global temperature change and economic growth of recipient countries, but they do result in differences in GDP changes for Japan and the FSU. The GDP-based principle results in a larger share of financial burden for Japan, while the historical emissions-based principle results in a larger share of financial burden for the FSU. A larger burden share leads to a greater GDP loss.

  15. Comparisons of observed seasonal climate features with a winter and summer numerical simulation produced with the GLAS general circulation model

    Science.gov (United States)

    Halem, M.; Shukla, J.; Mintz, Y.; Wu, M. L.; Godbole, R.; Herman, G.; Sud, Y.

    1979-01-01

    Results are presented from numerical simulations performed with the general circulation model (GCM) for winter and summer. The monthly mean simulated fields for each integration are compared with observed geographical distributions and zonal averages. In general, the simulated sea level pressure and upper level geopotential height field agree well with the observations. Well simulated features are the winter Aleutian and Icelandic lows, the summer southwestern U.S. low, the summer and winter oceanic subtropical highs in both hemispheres, and the summer upper level Tibetan high and Atlantic ridge. The surface and upper air wind fields in the low latitudes are in good agreement with the observations. The geographical distirbutions of the Earth-atmosphere radiation balance and of the precipitation rates over the oceans are well simulated, but not all of the intensities of these features are correct. Other comparisons are shown for precipitation along the ITCZ, rediation balance, zonally averaged temperatures and zonal winds, and poleward transports of momentum and sensible heat.

  16. Selecting global climate models for regional climate change studies

    Science.gov (United States)

    Pierce, David W.; Barnett, Tim P.; Santer, Benjamin D.; Gleckler, Peter J.

    2009-01-01

    Regional or local climate change modeling studies currently require starting with a global climate model, then downscaling to the region of interest. How should global models be chosen for such studies, and what effect do such choices have? This question is addressed in the context of a regional climate detection and attribution (D&A) study of January-February-March (JFM) temperature over the western U.S. Models are often selected for a regional D&A analysis based on the quality of the simulated regional climate. Accordingly, 42 performance metrics based on seasonal temperature and precipitation, the El Nino/Southern Oscillation (ENSO), and the Pacific Decadal Oscillation are constructed and applied to 21 global models. However, no strong relationship is found between the score of the models on the metrics and results of the D&A analysis. Instead, the importance of having ensembles of runs with enough realizations to reduce the effects of natural internal climate variability is emphasized. Also, the superiority of the multimodel ensemble average (MM) to any 1 individual model, already found in global studies examining the mean climate, is true in this regional study that includes measures of variability as well. Evidence is shown that this superiority is largely caused by the cancellation of offsetting errors in the individual global models. Results with both the MM and models picked randomly confirm the original D&A results of anthropogenically forced JFM temperature changes in the western U.S. Future projections of temperature do not depend on model performance until the 2080s, after which the better performing models show warmer temperatures. PMID:19439652

  17. Evaluation of a present-day climate simulation with a new coupled atmosphere-ocean model GENMOM

    Directory of Open Access Journals (Sweden)

    J. R. Alder

    2011-02-01

    Full Text Available We present a new, non-flux corrected AOGCM, GENMOM, that combines the GENESIS version 3 atmospheric GCM (Global Environmental and Ecological Simulation of Interactive Systems and MOM2 (Modular Ocean Model version 2 nominally at T31 resolution. We evaluate GENMOM by comparison with reanalysis products (e.g., NCEP2 and three models used in the IPCC AR4 assessment. GENMOM produces a global temperature bias of 0.6 °C. Atmospheric features such as the jet stream structure and major semi-permanent sea level pressure centers are well simulated as is the mean planetary-scale wind structure that is needed to produce the correct position of stormtracks. Most ocean surface currents are reproduced except where they are not resolvable at T31 resolution. Overall, GENMOM captures reasonably well the observed gradients and spatial distributions of annual surface temperature and precipitation and the simulations are on par with other AOGCMs. Deficiencies in the GENMOM simulations include a warm bias in the surface temperature over the southern oceans, a split in the ITCZ and weaker-than-observed overturning circulation.

  18. Climate Model Diagnostic Analyzer Web Service System

    Science.gov (United States)

    Lee, S.; Pan, L.; Zhai, C.; Tang, B.; Kubar, T. L.; Li, J.; Zhang, J.; Wang, W.

    2015-12-01

    Both the National Research Council Decadal Survey and the latest Intergovernmental Panel on Climate Change Assessment Report stressed the need for the comprehensive and innovative evaluation of climate models with the synergistic use of global satellite observations in order to improve our weather and climate simulation and prediction capabilities. The abundance of satellite observations for fundamental climate parameters and the availability of coordinated model outputs from CMIP5 for the same parameters offer a great opportunity to understand and diagnose model biases in climate models. In addition, the Obs4MIPs efforts have created several key global observational datasets that are readily usable for model evaluations. However, a model diagnostic evaluation process requires physics-based multi-variable comparisons that typically involve large-volume and heterogeneous datasets, making them both computationally- and data-intensive. In response, we have developed a novel methodology to diagnose model biases in contemporary climate models and implementing the methodology as a web-service based, cloud-enabled, provenance-supported climate-model evaluation system. The evaluation system is named Climate Model Diagnostic Analyzer (CMDA), which is the product of the research and technology development investments of several current and past NASA ROSES programs. The current technologies and infrastructure of CMDA are designed and selected to address several technical challenges that the Earth science modeling and model analysis community faces in evaluating and diagnosing climate models. In particular, we have three key technology components: (1) diagnostic analysis methodology; (2) web-service based, cloud-enabled technology; (3) provenance-supported technology. The diagnostic analysis methodology includes random forest feature importance ranking, conditional probability distribution function, conditional sampling, and time-lagged correlation map. We have implemented the

  19. Evaluating adaptation options for urban flooding based on new high-end emission scenario regional climate model simulations

    DEFF Research Database (Denmark)

    Arnbjerg-Nielsen, Karsten; Leonardsen, L.; Madsen, Henrik

    2015-01-01

    a regional climate model projection forced to a global temperature increase of 6 degrees C in 2100 as well as a projection based on a high radiative forcing scenario (RCP8.5). With these scenarios, projected impacts of extreme precipitation increase significantly. For extreme sea surges, the impacts do...... by almost 4 and 8 times the current EAD for the RCP8.5 and 6 degrees C scenario, respectively. For both hazards, business-as-usual is not a possible scenario, since even in the absence of policy-driven changes, significant autonomous adaptation is likely to occur. Copenhagen has developed an adaptation plan...... is significantly reduced (corresponding to 0.6-1.0 and 1.2-2.1 times the current EAD for the RCP8.5 and 6 degrees C scenario, respectively)....

  20. The Community Climate System Model: CCSM3

    Energy Technology Data Exchange (ETDEWEB)

    Collins, W D; Blackmon, M; Bitz, C; Bonan, G; Bretherton, C S; Carton, J A; Chang, P; Doney, S; Hack, J J; Kiehl, J T; Henderson, T; Large, W G; McKenna, D; Santer, B D; Smith, R D

    2004-12-27

    A new version of the Community Climate System Model (CCSM) has been developed and released to the climate community. CCSM3 is a coupled climate model with components representing the atmosphere, ocean, sea ice, and land surface connected by a flux coupler. CCSM3 is designed to produce realistic simulations over a wide range of spatial resolutions, enabling inexpensive simulations lasting several millennia or detailed studies of continental-scale climate change. This paper will show results from the configuration used for climate-change simulations with a T85 grid for atmosphere and land and a 1-degree grid for ocean and sea-ice. The new system incorporates several significant improvements in the scientific formulation. The enhancements in the model physics are designed to reduce or eliminate several systematic biases in the mean climate produced by previous editions of CCSM. These include new treatments of cloud processes, aerosol radiative forcing, land-atmosphere fluxes, ocean mixed-layer processes, and sea-ice dynamics. There are significant improvements in the sea-ice thickness, polar radiation budgets, equatorial sea-surface temperatures, ocean currents, cloud radiative effects, and ENSO teleconnections. CCSM3 can produce stable climate simulations of millenial duration without ad hoc adjustments to the fluxes exchanged among the component models. Nonetheless, there are still systematic biases in the ocean-atmosphere fluxes in western coastal regions, the spectrum of ENSO variability, the spatial distribution of precipitation in the Pacific and Indian Oceans, and the continental precipitation and surface air temperatures. We conclude with the prospects for extending CCSM to a more comprehensive model of the Earth's climate system.

  1. Improvements in Climate Simulation with Modifications to the Tiedtke Convective Parameterization in the Grid-Point Atmospheric Model of IAP LASG (GAMIL)

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The grid-point atmospheric model of IAP LASG (GAMIL) was developed in and has been evaluated since early 2004. Although the model shows its ability in simulating the global climate, it suffers from some problems in simulating precipitation in the tropics. These biases seem to result mainly from the treatment of the subgrid scale convection, which is parameterized with Tiedtke's massflux scheme (or the Zhang-McFarlane scheme, as an option) in the model. In order to reduce the systematic biases, several modifications were made to the Tiedtke scheme used in GAMIL, including (1) an increase in lateral convective entrainment/detrainment rate for shallow convection, (2) inclusion of a relative humidity threshold for the triggering of deep convection, and (3) a reduced efficiency for the conversion of cloud water to rainwater in the convection scheme.Two experiments, one with the original Tiedtke scheme used in GAMIL and the other with the modified scheme, were conducted to evaluate the performance of the modified scheme in this study. The results show that both the climatological mean state, such as precipitation, temperature and specific humidity, and interannual variability in the model simulation are improved with the use of this modified scheme. Results from several additional experiments show that the improvements in the model performance in different regions mainly result from either the introduction of the relative humidity threshold for triggering of the deep convection or the suppressed shallow convection due to enhanced lateral convective entrainment/detrainment rates.

  2. Simulation of the Atlantic meridional overturning circulation in an atmosphere-ocean global coupled model. Part II: weakening in a climate change experiment: a feedback mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Guemas, Virginie [Meteo-France, CNRS, Centre National de Recherches Meteorologiques/Groupe d' Etude de l' Atmosphere Meteorologique (CNRM/GMGEC), Toulouse Cedex (France); CEA-CNRS-UVSQ, Laboratoire des Sciences du Climat et de l' Environnement, UMR 1572, Gif-sur-Yvette (France); Salas-Melia, David [Meteo-France, CNRS, Centre National de Recherches Meteorologiques/Groupe d' Etude de l' Atmosphere Meteorologique (CNRM/GMGEC), Toulouse Cedex (France)

    2008-06-15

    Most state-of-the art global coupled models simulate a weakening of the Atlantic meridional overturning circulation (MOC) in climate change scenarios but the mechanisms leading to this weakening are still being debated. The third version of the CNRM (Centre National de Recherches Meteorologiques) global atmosphere-ocean-sea ice coupled model (CNRM-CM3) was used to conduct climate change experiments for the Intergovernmental Panel on Climate Change Fourth Assessment Report (IPCC AR4). The analysis of the A1B scenario experiment shows that global warming leads to a slowdown of North Atlantic deep ocean convection and thermohaline circulation south of Iceland. This slowdown is triggered by a freshening of the Arctic Ocean and an increase in freshwater outflow through Fram Strait. Sea ice melting in the Barents Sea induces a local amplification of the surface warming, which enhances the cyclonic atmospheric circulation around Spitzberg. This anti-clockwise circulation forces an increase in Fram Strait outflow and a simultaneous increase in ocean transport of warm waters toward the Barents Sea, favouring further sea ice melting and surface warming in the Barents Sea. Additionally, the retreat of sea ice allows more deep water formation north of Iceland and the thermohaline circulation strengthens there. The transport of warm and saline waters toward the Barents Sea is further enhanced, which constitutes a second positive feedback. (orig.)

  3. Understanding the past to interpret the future: comparison of simulated groundwater recharge in the upper Colorado River basin (USA) using observed and general-circulation-model historical climate data

    Science.gov (United States)

    Tillman, Fred D.; Gangopadhyay, Subhrendu; Pruitt, Tom

    2016-10-01

    In evaluating potential impacts of climate change on water resources, water managers seek to understand how future conditions may differ from the recent past. Studies of climate impacts on groundwater recharge often compare simulated recharge from future and historical time periods on an average monthly or overall average annual basis, or compare average recharge from future decades to that from a single recent decade. Baseline historical recharge estimates, which are compared with future conditions, are often from simulations using observed historical climate data. Comparison of average monthly results, average annual results, or even averaging over selected historical decades, may mask the true variability in historical results and lead to misinterpretation of future conditions. Comparison of future recharge results simulated using general circulation model (GCM) climate data to recharge results simulated using actual historical climate data may also result in an incomplete understanding of the likelihood of future changes. In this study, groundwater recharge is estimated in the upper Colorado River basin, USA, using a distributed-parameter soil-water balance groundwater recharge model for the period 1951-2010. Recharge simulations are performed using precipitation, maximum temperature, and minimum temperature data from observed climate data and from 97 CMIP5 (Coupled Model Intercomparison Project, phase 5) projections. Results indicate that average monthly and average annual simulated recharge are similar using observed and GCM climate data. However, 10-year moving-average recharge results show substantial differences between observed and simulated climate data, particularly during period 1970-2000, with much greater variability seen for results using observed climate data.

  4. Understanding the past to interpret the future: comparison of simulated groundwater recharge in the upper Colorado River basin (USA) using observed and general-circulation-model historical climate data

    Science.gov (United States)

    Tillman, Fred D.; Gangopadhyay, Subhrendu; Pruitt, Tom

    2017-03-01

    In evaluating potential impacts of climate change on water resources, water managers seek to understand how future conditions may differ from the recent past. Studies of climate impacts on groundwater recharge often compare simulated recharge from future and historical time periods on an average monthly or overall average annual basis, or compare average recharge from future decades to that from a single recent decade. Baseline historical recharge estimates, which are compared with future conditions, are often from simulations using observed historical climate data. Comparison of average monthly results, average annual results, or even averaging over selected historical decades, may mask the true variability in historical results and lead to misinterpretation of future conditions. Comparison of future recharge results simulated using general circulation model (GCM) climate data to recharge results simulated using actual historical climate data may also result in an incomplete understanding of the likelihood of future changes. In this study, groundwater recharge is estimated in the upper Colorado River basin, USA, using a distributed-parameter soil-water balance groundwater recharge model for the period 1951-2010. Recharge simulations are performed using precipitation, maximum temperature, and minimum temperature data from observed climate data and from 97 CMIP5 (Coupled Model Intercomparison Project, phase 5) projections. Results indicate that average monthly and average annual simulated recharge are similar using observed and GCM climate data. However, 10-year moving-average recharge results show substantial differences between observed and simulated climate data, particularly during period 1970-2000, with much greater variability seen for results using observed climate data.

  5. Global climate simulations at 3000 year intervals for the last 21 000 years with the GENMOM coupled atmosphere–ocean model

    Directory of Open Access Journals (Sweden)

    J. R. Alder

    2014-07-01

    Full Text Available We apply GENMOM, a coupled atmosphere–ocean climate model, to simulate eight equilibrium "time-segments" at 3000 yr intervals for the past 21 000 years forced by changes in Earth-Sun geometry, atmospheric greenhouse gases (GHGs, continental ice sheets and sea level. Simulated global cooling during the Last Glacial Maximum (LGM is 3.8 °C and the rate of post-glacial warming is in overall agreement with recently published temperature reconstructions. The greatest rate of warming occurs between 15 and 12 ka (2.4 °C over land, 0.7 °C over oceans and 1.4 °C globally in response to changes in radiative forcing from the diminished extent of the Northern Hemisphere (NH ice sheets and increases in GHGs and NH summer insolation. The modeled LGM and 6 ka temperature and precipitation climatologies are generally consistent with proxy reconstructions, the PMIP2 and PMIP3 simulations, and other paleoclimate data-model analyses. The model does not capture the mid-Holocene "thermal maximum" and gradual cooling to pre-industrial global temperature found in the data. Simulated monsoonal precipitation in North Africa peaks between 12 and 9 ka at values ~ 50% greater than those of the PI, and Indian monsoonal precipitation peaks at 12 and 9 ka at values ~ 45% greater than the PI. GENMOM captures the reconstructed LGM extent of NH and Southern Hemisphere (SH sea ice. The simulated present-day Antarctica Circumpolar Current (ACC is ~ 48% weaker than observed (62 vs. 119 Sv. The simulated present-day Atlantic Meridional Overturning Circulation (AMOC of 19.3 ± 1.4 Sv on the Bermuda Rise (33° N is comparable with the observed value of 17.4 Sv. AMOC at 33° N is reduced by ~ 15% during the LGM, and the largest post-glacial increase (~ 11% occurs, unforced, during the 15 ka time slice.

  6. A new version of the CNRM Chemistry-Climate Model, CNRM-CCM: description and improvements from the CCMVal-2 simulations

    Directory of Open Access Journals (Sweden)

    M. Michou

    2011-10-01

    Full Text Available This paper presents a new version of the Météo-France CNRM Chemistry-Climate Model, so-called CNRM-CCM. It includes some fundamental changes from the previous version (CNRM-ACM which was extensively evaluated in the context of the CCMVal-2 validation activity. The most notable changes concern the radiative code of the GCM, and the inclusion of the detailed stratospheric chemistry of our Chemistry-Transport model MOCAGE on-line within the GCM. A 47-yr transient simulation (1960–2006 is the basis of our analysis. CNRM-CCM generates satisfactory dynamical and chemical fields in the stratosphere. Several shortcomings of CNRM-ACM simulations for CCMVal-2 that resulted from an erroneous representation of the impact of volcanic aerosols as well as from transport deficiencies have been eliminated.

    Remaining problems concern the upper stratosphere (5 to 1 hPa where temperatures are too high, and where there are biases in the NO2, N2O5 and O3 mixing ratios. In contrast, temperatures at the tropical tropopause are too cold. These issues are addressed through the implementation of a more accurate radiation scheme at short wavelengths. Despite these problems we show that this new CNRM CCM is a useful tool to study chemistry-climate applications.

  7. An empirical model simulating diurnal and seasonal CO2 flux for diverse vegetation types and climate conditions

    Directory of Open Access Journals (Sweden)

    A. D. Richardson

    2009-04-01

    Full Text Available We present an empirical model for the estimation of diurnal variability in net ecosystem CO2 exchange (NEE in various biomes. The model is based on the use of a simple saturated function for photosynthetic response of the canopy, and was constructed using the AmeriFlux network dataset that contains continuous eddy covariance CO2 flux data obtained at 24 ecosystems sites from seven biomes. The physiological parameters of maximum CO2 uptake rate by the canopy and ecosystem respiration have biome-specific responses to environmental variables. The model uses simplified empirical expression of seasonal variability in biome-specific physiological parameters based on air temperature, vapor pressure deficit, and annual precipitation. The model was validated using measurements of NEE derived from 10 AmeriFlux and four AsiaFlux ecosystem sites. The predicted NEE had reasonable magnitude and seasonal variation and gave adequate timing for the beginning and end of the growing season; the model explained 83–95% and 76–89% of the observed diurnal variations in NEE for the AmeriFlux and AsiaFlux ecosystem sites used for validation, respectively. The model however worked less satisfactorily in two deciduous broadleaf forests, a grassland, a savanna, and a tundra ecosystem sites where leaf area index changed rapidly. These results suggest that including additional plant physiological parameters may improve the model simulation performance in various areas of biomes.

  8. Stratospheric Ozone and Temperature Changes in the Past: The Impact of Increased Concentrations of CFCs in Simulations with a Chemistry-Climate Model

    Science.gov (United States)

    Meul, S.; Oberländer, S.; Abalichin, J.; Kubin, A.; Langematz, U.

    2012-04-01

    Changes in stratospheric ozone between 1960 and the end of the 20th century are investigated analysing simulations with the Chemistry-Climate-Model (CCM) EMAC in FUB configuration (i.e. 39 layers with FUBRad parameterisation). In order to analyse the impact of increasing emissions of chlorofluorocarbons (CFCs) from 1960 to 2000 two sensitivity studies have been performed: a reference simulation with boundary conditions for the year 2000 and one analogue simulation but with CFC emissions reduced to 1960 levels. By comparing to a transient simulation (1960 to 2100) using the CCMVal SCN-B2d scenario it is possible to isolate the ozone changes that are caused by the CFC-increase only and separate the CFC-effect from other processes affecting ozone, e.g. climate change. By applying the method of Garny et al. (2011) the relative ozone changes arising from the CFC-modification can be attributed to changes in transport, chemical production and loss. Furthermore, it is analysed how the processes related to the CFC-increase contribute to the stratospheric cooling of up to 4K that is simulated by the SCN-B2d run between the 1960s and the 2000s in the upper stratosphere. The temperature change due to increased CFCs is caused by a reduced absorption of solar radiation by decreased ozone concentrations combined with the greenhouse gas (GHG) effect of the CFCs. In the upper stratosphere a cooling of up to 2.5K can be explained by the CFC-increase.

  9. Water Vapor Transport and Cross-Equatorial Flow over the Asian-Australia Monsoon Region Simulated by CMIP5 Climate Models

    Institute of Scientific and Technical Information of China (English)

    SONG Yajuan; QIAO Fangli; SONG Zhenya; JIANG Chunfei

    2013-01-01

    The summer mean water vapor transport (WVT) and cross-equatorial flow (CEF) over the AsianAustralian monsoon region simulated by 22 coupled atmospheric-oceanic general circulation models (AOGCMs)from the World Climate Research Programme's Coupled Model Intercomparison Project Phase 5 (CMIP5)were evaluated.Based on climatology of the twentieth-century simulations,most of models have a reasonably realistic representation of summer monsoon WVT characterized by southeast water vapor conveyor belt over the South Indian Ocean and southwest belt from the Arabian Sea to the East Asian.The correlation coefficients between NCEP reanalysis and simulations of BCC-CSM1-1,BNU-ESM,CanESM2,FGOALS-s2,MIROC4h and MPI-ESM-LR are up to 0.8.The simulated CEF depicted by the meridional wind along the equator includes the Somali jet and eastern CEF in low atmosphere and the reverse circulation in upper atmosphere,which were generally consistent with NCEP reanalysis.Multi-model ensemble means (MME) can reproduce more reasonable climatological features in spatial distribution both of WVT and CEF.Ten models with more reasonable WVT simulations were selected for future projection studies,including BCCCSM1-1,BNU-ESM,CanESM2,CCSM4,FGOALS-s2,FIO-ESM,GFDL-ESM2G,MRIOC5,MPI-ESM-LR and NorESM-1M.Analysis based on the future projection experiments in RCP (Representative Concentration Pathway) 2.6,RCP4.5,RCP6 and RCP8.5 show that the global warming forced by different RCP scenarios will results in enhanced WVT over the Indian area and the west Pacific and weaken WVT in the low latitudes of tropical Indian Ocean.

  10. CMIP5 model-simulated onset, duration and intensity of the Asian summer monsoon in current and future climate

    Science.gov (United States)

    Dong, Guangtao; Zhang, H.; Moise, A.; Hanson, L.; Liang, P.; Ye, H.

    2016-01-01

    A number of significant weaknesses existed in our previous analysis of the changes in the Asian monsoon onset/retreat from coupled model intercomparison project phase 3 (CMIP3) models, including a lack of statistical significance tests, a small number of models analysed, and limited understanding of the causes of model uncertainties. Yet, the latest IPCC report acknowledges limited confidence for projected changes in monsoon onset/retreat. In this study we revisit the topic by expanding the analysis to a large number of CMIP5 models over much longer period and with more diagnoses. Daily 850 hPa wind, volumetric atmospheric precipitable water and rainfall data from 26 CMIP5 models over two sets of 50-year periods are used in this study. The overall model skill in reproducing the temporal and spatial patterns of the monsoon development is similar between CMIP3 and CMIP5 models. They are able to show distinct regional characteristics in the evolutions of Indian summer monsoon (ISM), East Asian summer monsoon (EASM) and West North Pacific summer monsoon (WNPSM). Nevertheless, the averaged onset dates vary significantly among the models. Large uncertainty exists in model-simulated changes in onset/retreat dates and the extent of uncertainty is comparable to that in CMIP3 models. Under global warming, a majority of the models tend to suggest delayed onset for the south Asian monsoon in the eastern part of tropical Indian Ocean and Indochina Peninsula and nearby region, primarily due to weakened tropical circulations and eastward shift of the Walker circulation. The earlier onset over the Arabian Sea and part of the Indian subcontinent in a number of the models are related to an enhanced southwesterly flow in the region. Weak changes in other domains are due to the offsetting results among the models, with some models showing earlier onsets but others showing delayed onsets. Different from the analysis of CMIP3 model results, this analysis highlights the importance of SST

  11. Sensitivity of the Himalayan orography representation in simulation of winter precipitation using Regional Climate Model (RegCM) nested in a GCM

    Science.gov (United States)

    Tiwari, P. R.; Kar, S. C.; Mohanty, U. C.; Dey, S.; Sinha, P.; Shekhar, M. S.

    2017-02-01

    The role of the Himalayan orography representation in a Regional Climate Model (RegCM4) nested in NCMRWF global spectral model is examined in simulating the winter circulation and associated precipitation over the Northwest India (NWI; 23°-37.5°N and 69°-85°E) region. For this purpose, nine different set of orography representations for nine distinct precipitation years (three years each for wet, normal and dry) have been considered by increasing (decreasing) 5, 10, 15, and 20% from the mean height (CNTRL) of the Himalaya in RegCM4 model. Validation with various observations revealed a good improvement in reproducing the precipitation intensity and distribution with increased model height compared to the results obtained from CNTRL and reduced orography experiments. Further it has been found that, increase in height by 10% (P10) increases seasonal precipitation about 20%, while decrease in height by 10% (M10) results around 28% reduction in seasonal precipitation as compared to CNTRL experiment over NWI region. This improvement in precipitation simulation comes due to better representation of vertical pressure velocity and moisture transport as these factors play an important role in wintertime precipitation processes over NWI region. Furthermore, a comparison of model-simulated precipitation with observed precipitation at 17 station locations has been also carried out. Overall, the results suggest that when the orographic increment of 10% (P10) is applied on RegCM4 model, it has better skill in simulating the precipitation over the NWI region and this model is a useful tool for further regional downscaling studies.

  12. Impacts of Upper Tropospheric Cooling upon the Late Spring Drought in East Asia Simulated by a Regional Climate Model

    Institute of Scientific and Technical Information of China (English)

    XIN Xiaoge; Zhaoxin LI; YU Rucong; ZHOU Tianjun

    2008-01-01

    Responses of late spring (21 April-20 May) rainfall to the upper tropospheric cooling over East Asia are investigated with a regional climate model based on Laboratoire de Météorologie Dynamique Zoom (LMDZ4-RCM). A control experiment is performed with two runs driven by the mean ERA-40 data during 1958-1977 and 1981-2000, respectively. The model reproduces the major decadal-scale circulation changes in late spring over East Asia, including a cooling in the upper troposphere and an anomalous meridional cell. Accordingly, the precipitation decrease is also captured in the southeast of the upper-level cooling region. To quantify the role of the upper-level cooling in the drought mechanism, a sensitivity experiment is further conducted with the cooling imposed in the upper troposphere. It is demonstrated that the upper-level cooling can generate the anomalous meridional cell and consequently the drought to the southeast of the cooling center. Therefore, upper tropospheric cooling should have played a dominant role in the observed late spring drought over Southeast China in recent decades.

  13. Changes in Winter Stratospheric Circulation in CMIP5 Scenarios Simulated by the Climate System Model FGOALS-s2

    Institute of Scientific and Technical Information of China (English)

    REN Rongcai; YANG Yang

    2012-01-01

    Diagnosis of changes in the winter stratospheric circulation in the Fifth Coupled Model Intercomparison Project (CMIP5) scenarios simulated by the Flexible Global Ocean-Atmosphere-Land System model,second version spectrum (FGOALS-s2),indicates that the model can generally reproduce the present climatology of the stratosphere and can capture the general features of its long-term changes during 1950 2000,including the global stratospheric cooling and the strengthening of the westerly polar jet,though the simulated polar vortex is much cooler,the jet is much stronger,and the projected changes are generally weaker than those revealed by observation data.With the increase in greenhouse gases (GHGs) effect in the historical simulation from 1850 to 2005 (called the HISTORICAL run) and the two future projections for Representative Concentration Pathways (called the RCP4.5 and RCP8.5 scenarios) from 2006 to 2100,the stratospheric response was generally steady,with an increasing stratospheric cooling and a strengthening polar jet extending equatorward.Correspondingly,the leading oscillation mode,defined as the Polar Vortex Oscillation (PVO),exhibited a clear positive trend in each scenario,confirming the steady strengthening of the polar vortex.However,the positive trend of the PVO and the strengthening of the polar jet were not accompanied by decreased planetary-wave dynamical heating,suggesting that the cause of the positive PVO trend and the polar stratospheric cooling trend is probably the radiation cooling effect due to increase in GHGs.Nevertheless,without the long-term linear trend,the temporal variations of the wave dynamic heating,the PVO,and the polar stratospheric temperature are still closely coupled in the interannual and decadal time scales.

  14. 35 ka BP climate simulations in East Asia and probing the mechanisms of climate changes

    Institute of Scientific and Technical Information of China (English)

    YU Ge; ZHENG Yiqun; KE Xiankun

    2005-01-01

    Paleoclimate modeling has become an important tool to detect the future climate of the global warming that is difficult to be validated. The paleoclimate modeling has to be evaluated by regionally geological data in order to determine if it is able to reproduce a reality of climate states. Geological evidence shows that there was a warm-wet interstadial at 35000±3000 a BP in China, which provides an important climate period to be historical analogue for the future climate changes induced by greenhouse gas emissions. Integrated geological records of later phase of the MSI3 from China also provide basements for evaluation of 35 ka BP climate modeling. This paper reports the paleoclimate experiments applied by various forces, and validates the outputs by geological data, consequently improving the boundary conditions in the experiments and making the paleoclimates more approach the reality. The simulations show an increased temperature in the mid-low latitudes and an extended rain-belt northwards in East Asia, while a decreased temperature in high latitudes and a strong exchange of the N-S atmospheric circulation. As there is only ca. 10-15 ka from 35 ka BP to the LGM (21 ka BP) during which climate rapidly changed from a warm-wet interstadial to a typical ice age, this simulation provides scientific basis to recognize the criteria of global warming and trends of natural climate development.

  15. Calibration, uncertainties and use of soybean crop simulation models for evaluating strategies to mitigate the effects of climate change in Southern Brazil

    OpenAIRE

    Rafael Battisti

    2016-01-01

    The water deficit is a major factor responsible for the soybean yield gap in Southern Brazil and tends to increase under climate change. Crop models are a tool that differ on levels of complexity and performance and can be used to evaluate strategies to manage crops, according the climate conditions. Based on that, the aims of this study were: to assess five soybean crop models and their ensemble; to evaluate the sensitivity of these models to systematic changes in climate; to assess soybean ...

  16. Uncertainty Quantification in Climate Modeling

    Science.gov (United States)

    Sargsyan, K.; Safta, C.; Berry, R.; Debusschere, B.; Najm, H.

    2011-12-01

    We address challenges that sensitivity analysis and uncertainty quantification methods face when dealing with complex computational models. In particular, climate models are computationally expensive and typically depend on a large number of input parameters. We consider the Community Land Model (CLM), which consists of a nested computational grid hierarchy designed to represent the spatial heterogeneity of the land surface. Each computational cell can be composed of multiple land types, and each land type can incorporate one or more sub-models describing the spatial and depth variability. Even for simulations at a regional scale, the computational cost of a single run is quite high and the number of parameters that control the model behavior is very large. Therefore, the parameter sensitivity analysis and uncertainty propagation face significant difficulties for climate models. This work employs several algorithmic avenues to address some of the challenges encountered by classical uncertainty quantification methodologies when dealing with expensive computational models, specifically focusing on the CLM as a primary application. First of all, since the available climate model predictions are extremely sparse due to the high computational cost of model runs, we adopt a Bayesian framework that effectively incorporates this lack-of-knowledge as a source of uncertainty, and produces robust predictions with quantified uncertainty even if the model runs are extremely sparse. In particular, we infer Polynomial Chaos spectral expansions that effectively encode the uncertain input-output relationship and allow efficient propagation of all sources of input uncertainties to outputs of interest. Secondly, the predictability analysis of climate models strongly suffers from the curse of dimensionality, i.e. the large number of input parameters. While single-parameter perturbation studies can be efficiently performed in a parallel fashion, the multivariate uncertainty analysis

  17. Impact of absorbing aerosols on the simulation of climate over the Indian region in an atmospheric general circulation model

    Directory of Open Access Journals (Sweden)

    A. Chakraborty

    2004-04-01

    Full Text Available The impact of anthropogenic absorbing aerosols (such as soot on the climate over the Indian region has been studied using the NCMRWF general circulation model. The absorbing aerosols increase shortwave radiative heating of the lower troposphere and reduce the heating at the surface. These effects have been incorporated as heating of the lower troposphere (up to 700hPa and cooling over the continental surface based on INDOEX measurements. The heating effect is constant in the pre-monsoon season and reduces to zero during the monsoon season. It is shown that even in the monsoon season when the aerosol forcing is zero, there is an overall increase in rainfall and a reduction in surface temperature over the Indian region. The rainfall averaged over the Tropics shows a small reduction in most of the months during the January to September period. The impact of aerosol forcing, the model's sensitivity to this forcing and its interaction with model-physics has been studied by changing the cumulus parameterization from the Simplified Arakawa-Schubert (SAS scheme to the Kuo scheme. During the pre-monsoon season the major changes in precipitation occur in the oceanic Inter Tropical Convergence Zone (ITCZ, where both the schemes show an increase in precipitation. This result is similar to that reported in Chung2002. On the other hand, during the monsoon season the changes in precipitation in the continental region are different in the SAS and Kuo schemes. It is shown that the heating due to absorbing aerosols changes the vertical moist-static stability of the atmosphere. The difference in the precipitation changes in the two cumulus schemes is on account of the different responses in the two parameterization schemes to changes in vertical stability.

    Key words. Atmospheric composition and structure (aerosols and particles – Meteorology and atmospheric dynamics (tropical meteorology; precipitation

  18. Simulating Baltic Sea climate for the period 1902-1998 with the Rossby Centre coupled ice-ocean model

    Energy Technology Data Exchange (ETDEWEB)

    Meier, H.E. Markus [Swedish Meteorological and Hydrological Inst., Rossby Centre, Norrkoeping (Sweden); Kauker, Frank [Alfred Wegener Inst. for Polar and Marine Research, Bremerhaven (Germany)

    2002-12-01

    Hindcast simulations for the period 1902-1998 have been performed using a 3D coupled ice-ocean model for the Baltic Sea. Daily sea level observations in Kattegat, monthly basin-wide discharge data, and reconstructed atmospheric surface data have been used to force the Baltic Sea model. The reconstruction utilizes a statistical model to calculate daily sea level pressure and monthly surface air temperature, dew point temperature, precipitation, and cloud cover fields on a 1 deg x 1 deg regular horizontal grid for the Baltic Sea region. An improved turbulence scheme has been implemented into the Baltic Sea model to simulate saltwater inflows realistically. The results are validated against available observational datasets for sea level, salinity, saltwater inflow, volume transport, and sea ice. In addition, a comparison is performed with simulations for the period 1980-1993 using 3-hourly gridded atmospheric observations from synoptic stations. It is shown that the results of the Baltic Sea model forced with the reconstructed data are satisfactory. Sensitivity experiments have been performed to explore the impact of internal mixing, fresh and saltwater inflows, sea ice, and the sea level in Kattegat on the salinity of the Baltic Sea. It is found that the decadal variability of mean salinity is explained partly by decadal volume variations of the accumulated freshwater inflow from river runoff and net precipitation and partly by decadal variations of the large-scale sea level pressure over Scandinavia. During the last century two exceptionally long stagnation periods are found, the 1920s to the 1930s and the 1980s to the mid 1990s. During these periods precipitation, runoff and westerly winds were stronger than normal. Stronger westerly winds caused increased eastward surface-layer transports. Consequently, the mean eastward lower layer transports through the Stolpe Channel is reduced. The response time scale of the Baltic Sea is of the order of 30-40 years. The large

  19. Improved ENSO simulation from climate system model FGOALS-g1.0 to FGOALS-g2

    Science.gov (United States)

    Chen, Lin; Yu, Yongqiang; Zheng, Weipeng

    2016-10-01

    This study presents an overview of the improvement in the simulation of El Niño-Southern Oscillation (ENSO) in the latest generation of the Institute of Atmospheric Physics' coupled general circulation model (CGCM), the Flexible Global Ocean-Atmosphere-Land System model Grid-point Version 2 (FGOALS-g2; hereafter referred to as "g2") from its predecessor FGOALS-g1.0 (referred to as "g1"), including the more realistic amplitude, irregularity, and ENSO cycle. The changes have been analyzed quantitatively based on the Bjerknes stability index, which serves as a measure of ENSO growth rate. The improved simulation of ENSO amplitude is mainly due to the reasonable representation of the thermocline and thermodynamic feedbacks: On the one hand, the deeper mean thermocline results in a weakened thermocline response to the zonal wind stress anomaly, and the looser vertical stratification of mean temperature leads to a weakened response of anomalous subsurface temperature to anomalous thermocline depth, both of which cause the reduced thermocline feedback in g2; on the other hand, the alleviated cold bias of mean sea surface temperature leads to more reasonable thermodynamic feedback in g2. The regular oscillation of ENSO in g1 is associated with its unsuccessful representation of the role of atmospheric noise over the western-central equatorial Pacific (WCEP) in triggering ENSO events, which arises from the weak synoptic-intraseasonal variability of zonal winds over the WCEP in g1. The asymmetric transition of ENSO in g1 is attributed to the asymmetric effect of thermocline feedback, which is due to the annual cycle of mean upwelling in the eastern Pacific. This study highlights the great impact of improving the representation of mean states on the improved simulation of air-sea feedback processes and ultimately more reasonable depiction of ENSO behaviors in CGCMs.

  20. Hydrological Cycle in the Danube basin in present-day and XXII century simulations by IPCCAR4 global climate models

    CERN Document Server

    Lucarini, Valerio; Kriegerova, Ida; Speranza, Antonio; 10.1029/2007JD009167

    2011-01-01

    We present an intercomparison and verification analysis of 20 GCMs included in the 4th IPCC assessment report regarding their representation of the hydrological cycle on the Danube river basin for 1961-2000 and for the 2161-2200 SRESA1B scenario runs. The basin-scale properties of the hydrological cycle are computed by spatially integrating the precipitation, evaporation, and runoff fields using the Voronoi-Thiessen tessellation formalism. The span of the model simulated mean annual water balances is of the same order of magnitude of the observed Danube discharge of the Delta; the true value is within the range simulated by the models. Some land components seem to have deficiencies since there are cases of violation of water conservation when annual means are considered. The overall performance and the degree of agreement of the GCMs are comparable to those of the RCMs analyzed in a previous work, in spite of the much higher resolution and common nesting of the RCMs. The reanalyses are shown to feature severa...

  1. Holism, entrenchment, and the future of climate model pluralism

    Science.gov (United States)

    Lenhard, Johannes; Winsberg, Eric

    In this paper, we explore the extent to which issues of simulation model validation take on novel characteristics when the models in question become particularly complex. Our central claim is that complex simulation models in general, and global models of climate in particular, face a form of confirmation holism. This holism, moreover, makes analytic understanding of complex models of climate either extremely difficult or even impossible. We argue that this supports a position we call convergence skepticism: the belief that the existence of a plurality of different models making a plurality of different forecasts of future climate is likely to be a persistent feature of global climate science.

  2. Evaluating the dominant components of warming in Pliocene climate simulations

    Directory of Open Access Journals (Sweden)

    D. J. Hill

    2013-03-01

    Full Text Available The Pliocene Model Intercomparison Project is the first coordinated climate model comparison for a warmer palaeoclimate with atmospheric CO2 significantly higher than pre-industrial concentrations. The simulations of the mid-Pliocene warm period show global warming of between 1.8 and 3.6 °C above pre-industrial surface air temperatures, with significant polar amplification. Here we perform energy balance calculations on all eight of the coupled ocean–atmosphere simulations within PlioMIP Experiment 2 to evaluate the causes of the increased temperatures and differences between the models. In the tropics simulated warming is dominated by greenhouse gas increases, with cloud albedo feedbacks enhancing the warming in most of the models, but by widely varying amounts. The responses to mid-Pliocene climate forcing in the Northern Hemisphere mid-latitudes are substantially different between the climate models, with the only consistent response being a warming due to increased greenhouse gases. In the high latitudes all the energy balance components become important, but the dominant warming influence comes from the clear sky albedo. This demonstrates the importance of specified ice sheet and high latitude vegetation boundary conditions and simulated sea ice and snow albedo feedbacks. The largest components in the overall uncertainty are associated with cloud albedo feedbacks in the tropics and polar clear sky albedo, particularly in sea ice regions. These simulations show that high latitude albedo feedbacks provide the most significant enhancements to Pliocene greenhouse warming.

  3. How does increasing horizontal resolution in a global climate model improve the simulation of aerosol-cloud interactions?

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Po -Lun [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); Rasch, Philip J. [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); Wang, Minghuai [Nanjing Univ., Nanjing (China); Jiangsu Collaborative Innovation Center Climate Change, Nanjing (China); Wang, Hailong [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); Ghan, Steven J. [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); Easter, Richard C. [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); Gustafson, Jr., William I. [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); Liu, Xiaohong [Univ. of Wyo; Zhang, Yuying [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Ma, Hsi -Yen [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-06-28

    The Community Atmosphere Model Version 5 is run at horizontal grid spacing of 2, 1, 0.5, and 0.25 degrees, with the meteorology nudged towards the Year Of Tropical Convection analysis, and cloud simulators and the collocated A-Train satellite observations are used to explore the resolution dependence of aerosol-cloud interactions. The higher-resolution model produces results that agree better with observations, showing an increase of susceptibility of cloud droplet size, indicating a stronger first aerosol indirect forcing (AIF), and a decrease of susceptibility of precipitation probability, suggesting a weaker second AIF. The resolution sensitivities of AIF are attributed to those of droplet nucleation and precipitation parameterizations. The annual average AIF in the northern hemisphere mid-latitudes (where most anthropogenic emissions occur) in the 0.25° model is reduced by about 1 W m⁻² (-30%) compared to the 2° model, leading to a 0.26 W m⁻² reduction (-15%) in the global annual average AIF.

  4. Transient climate-carbon simulations of planetary geoengineering.

    Science.gov (United States)

    Matthews, H Damon; Caldeira, Ken

    2007-06-12

    Geoengineering (the intentional modification of Earth's climate) has been proposed as a means of reducing CO2-induced climate warming while greenhouse gas emissions continue. Most proposals involve managing incoming solar radiation such that future greenhouse gas forcing is counteracted by reduced solar forcing. In this study, we assess the transient climate response to geoengineering under a business-as-usual CO2 emissions scenario by using an intermediate-complexity global climate model that includes an interactive carbon cycle. We find that the climate system responds quickly to artificially reduced insolation; hence, there may be little cost to delaying the deployment of geoengineering strategies until such a time as "dangerous" climate change is imminent. Spatial temperature patterns in the geoengineered simulation are comparable with preindustrial temperatures, although this is not true for precipitation. Carbon sinks in the model increase in response to geoengineering. Because geoengineering acts to mask climate warming, there is a direct CO2-driven increase in carbon uptake without an offsetting temperature-driven suppression of carbon sinks. However, this strengthening of carbon sinks, combined with the potential for rapid climate adjustment to changes in solar forcing, leads to serious consequences should geoengineering fail or be stopped abruptly. Such a scenario could lead to very rapid climate change, with warming rates up to 20 times greater than present-day rates. This warming rebound would be larger and more sustained should climate sensitivity prove to be higher than expected. Thus, employing geoengineering schemes with continued carbon emissions could lead to severe risks for the global climate system.

  5. Climate Forcings and Climate Sensitivities Diagnosed from Coupled Climate Model Integrations

    Energy Technology Data Exchange (ETDEWEB)

    Forster, P M A F; Taylor, K E

    2006-07-25

    A simple technique is proposed for calculating global mean climate forcing from transient integrations of coupled Atmosphere Ocean General Circulation Models (AOGCMs). This 'climate forcing' differs from the conventionally defined radiative forcing as it includes semi-direct effects that account for certain short timescale responses in the troposphere. Firstly, we calculate a climate feedback term from reported values of 2 x CO{sub 2} radiative forcing and surface temperature time series from 70-year simulations by twenty AOGCMs. In these simulations carbon dioxide is increased by 1%/year. The derived climate feedback agrees well with values that we diagnose from equilibrium climate change experiments of slab-ocean versions of the same models. These climate feedback terms are associated with the fast, quasi-linear response of lapse rate, clouds, water vapor and albedo to global surface temperature changes. The importance of the feedbacks is gauged by their impact on the radiative fluxes at the top of the atmosphere. We find partial compensation between longwave and shortwave feedback terms that lessens the inter-model differences in the equilibrium climate sensitivity. There is also some indication that the AOGCMs overestimate the strength of the positive longwave feedback. These feedback terms are then used to infer the shortwave and longwave time series of climate forcing in 20th and 21st Century simulations in the AOGCMs. We validate the technique using conventionally calculated forcing time series from four AOGCMs. In these AOGCMs the shortwave and longwave climate forcings we diagnose agree with the conventional forcing time series within {approx}10%. The shortwave forcing time series exhibit order of magnitude variations between the AOGCMs, differences likely related to how both natural forcings and/or anthropogenic aerosol effects are included. There are also factor of two differences in the longwave climate forcing time series, which may indicate

  6. Building an advanced climate model: Program plan for the CHAMMP (Computer Hardware, Advanced Mathematics, and Model Physics) Climate Modeling Program

    Energy Technology Data Exchange (ETDEWEB)

    1990-12-01

    The issue of global warming and related climatic changes from increasing concentrations of greenhouse gases in the atmosphere has received prominent attention during the past few years. The Computer Hardware, Advanced Mathematics, and Model Physics (CHAMMP) Climate Modeling Program is designed to contribute directly to this rapid improvement. The goal of the CHAMMP Climate Modeling Program is to develop, verify, and apply a new generation of climate models within a coordinated framework that incorporates the best available scientific and numerical approaches to represent physical, biogeochemical, and ecological processes, that fully utilizes the hardware and software capabilities of new computer architectures, that probes the limits of climate predictability, and finally that can be used to address the challenging problem of understanding the greenhouse climate issue through the ability of the models to simulate time-dependent climatic changes over extended times and with regional resolution.

  7. Simulating the Black Saturday 2009 smoke plume with an interactive composition-climate model: Sensitivity to emissions amount, timing, and injection height

    Science.gov (United States)

    Field, Robert D.; Luo, Ming; Fromm, Mike; Voulgarakis, Apostolos; Mangeon, Stéphane; Worden, John

    2016-04-01

    We simulated the high-altitude smoke plume from the early February 2009 Black Saturday bushfires in southeastern Australia using the NASA Goddard Institute for Space Studies ModelE2. To the best of our knowledge, this is the first single-plume analysis of biomass burning emissions injected directly into the upper troposphere/lower stratosphere (UTLS) using a full-complexity composition-climate model. We compared simulated carbon monoxide (CO) to a new Aura Tropospheric Emission Spectrometer/Microwave Limb Sounder joint CO retrieval, focusing on the plume's initial transport eastward, anticyclonic circulation to the north of New Zealand, westward transport in the lower stratospheric easterlies, and arrival over Africa at the end of February. Our goal was to determine the sensitivity of the simulated plume to prescribed injection height, emissions amount, and emissions timing from different sources for a full-complexity model when compared to Aura. The most realistic plumes were obtained using injection heights in the UTLS, including one drawn from ground-based radar data. A 6 h emissions pulse or emissions tied to independent estimates of hourly fire behavior produced a more realistic plume in the lower stratosphere compared to the same emissions amount being released evenly over 12 or 24 h. Simulated CO in the plume was highly sensitive to the differences between emissions amounts estimated from the Global Fire Emissions Database and from detailed, ground-based estimates of fire growth. The emissions amount determined not only the CO concentration of the plume but also the proportion of the plume that entered the stratosphere. We speculate that this is due to either or both nonlinear CO loss with a weakened OH sink or plume self-lofting driven by shortwave absorption of the coemitted aerosols.

  8. The coupled chemistry-climate model LMDz-REPROBUS: description and evaluation of a transient simulation of the period 1980–1999

    Directory of Open Access Journals (Sweden)

    F. Lott

    2008-06-01

    Full Text Available We present a description and evaluation of the Chemistry-Climate Model (CCM LMDz-REPROBUS, which couples interactively the extended version of the Laboratoire de Météorologie Dynamique General Circulation Model (LMDz GCM and the stratospheric chemistry module of the REactive Processes Ruling the Ozone BUdget in the Stratosphere (REPROBUS model. The transient simulation evaluated here covers the period 1980–1999. The introduction of an interactive stratospheric chemistry module improves the model dynamical climatology, with a substantial reduction of the temperature biases in the lower tropical stratosphere. However, at high latitudes in the Southern Hemisphere, a negative temperature bias, that is already present in the GCM version, albeit with a smaller magnitude, leads to an overestimation of the ozone depletion and its vertical extent in the CCM. This in turn contributes to maintain low polar temperatures in the vortex, delay the break-up of the vortex and the recovery of polar ozone. The latitudinal and vertical variation of the mean age of air compares favourable with estimates derived from long-lived species measurements, though the model mean age of air is 1–3 years too young in the middle stratosphere. The model also reproduces the observed "tape recorder" in tropical total hydrogen (=H2O+2×CH4, but its propagation is about 30% too fast and its signal fades away slightly too quickly. The analysis of the global distributions of CH4 and N2O suggests that the subtropical transport barriers are correctly represented in the simulation. LMDz-REPROBUS also reproduces fairly well most of the spatial and seasonal variations of the stratospheric chemical species, in particular ozone. However, because of the Antarctic cold bias, large discrepancies are found for most species at high latitudes in the Southern Hemisphere during the spring and early summer. In the Northern Hemisphere, polar ozone depletion and its variability are underestimated

  9. On the reduced lifetime of nitrous oxide due to climate change induced acceleration of the Brewer-Dobson circulation as simulated by the MPI Earth System Model

    Science.gov (United States)

    Kracher, D.; Manzini, E.; Reick, C. H.; Schultz, M. G.; Stein, O.

    2014-12-01

    Greenhouse gas induced climate change will modify the physical conditions of the atmosphere. One of the projected changes is an acceleration of the Brewer-Dobson circulation in the stratosphere, as it has been shown in many model studies. This change in the stratospheric circulation consequently bears an effect on the transport and distribution of atmospheric components such as N2O. Since N2O is involved in ozone destruction, a modified distribution of N2O can be of importance for ozone chemistry. N2O is inert in the troposphere and decays only in the stratosphere. Thus, changes in the exchange between troposphere and stratosphere can also affect the stratospheric sink of N2O, and consequently its atmospheric lifetime. N2O is a potent greenhouse gas with a global warming potential of currently approximately 300 CO2-equivalents in a 100-year perspective. A faster decay in atmospheric N2O mixing ratios, i.e. a decreased atmospheric lifetime of N2O, will also reduce its global warming potential. In order to assess the impact of climate change on atmospheric circulation and implied effects on the distribution and lifetime of atmospheric N2O, we apply the Max Planck Institute Earth System Model, MPI-ESM. MPI-ESM consists of the atmospheric general circulation model ECHAM, the land surface model JSBACH, and MPIOM/HAMOCC representing ocean circulation and ocean biogeochemistry. Prognostic atmospheric N2O concentrations in MPI-ESM are determined by land N2O emissions, ocean-atmosphere N2O exchange and atmospheric tracer transport. As stratospheric chemistry is not explicitly represented in MPI-ESM, stratospheric decay rates of N2O are prescribed from a MACC MOZART simulation. Increasing surface temperatures and CO2 concentrations in the stratosphere impact atmospheric circulation differently. Thus, we conduct a series of transient runs with the atmospheric model of MPI-ESM to isolate different factors governing a shift in atmospheric circulation. From those transient

  10. Distributions and climate effects of atmospheric aerosols from the preindustrial era to 2100 along Representative Concentration Pathways (RCPs simulated using the global aerosol model SPRINTARS

    Directory of Open Access Journals (Sweden)

    T. Takemura

    2012-12-01

    Full Text Available Global distributions and associated climate effects of atmospheric aerosols were simulated using a global aerosol climate model, SPRINTARS, from 1850 to the present day and projected forward to 2100. Aerosol emission inventories used by the Coupled Model Intercomparison Project Phase 5 (CMIP5 were applied to this study. Scenarios based on the Representative Concentration Pathways (RCPs were used for the future projection. Aerosol loading in the atmosphere has already peaked and is now reducing in Europe and North America. However, in Asia where rapid economic growth is ongoing, aerosol loading is estimated to reach a maximum in the first half of this century. Atmospheric aerosols originating from the burning of biomass have maintained high loadings throughout the 21st century in Africa, according to the RCPs. Evolution of the adjusted forcing by direct and indirect aerosol effects over time generally correspond to the aerosol loading. The probable future pathways of global mean forcing differ based on the aerosol direct effect for different RCPs. Because aerosol forcing will be close to the preindustrial level by the end of the 21st century for all RCPs despite the continuous increases in greenhouse gases, global warming will be accelerated with reduced aerosol negative forcing.

  11. Distributions and climate effects of atmospheric aerosols from the preindustrial era to 2100 along Representative Concentration Pathways (RCPs simulated using a global aerosol model SPRINTARS

    Directory of Open Access Journals (Sweden)

    T. Takemura

    2012-08-01

    Full Text Available Global distributions and associated climate effects of atmospheric aerosols were simulated using a global aerosol climate model, SPRINTARS, from 1850 to the present day and projected forward to 2100. Aerosol emission inventories used by the Coupled Model Intercomparison Project Phase 5 (CMIP5 were applied to this study. Scenarios based on the Representative Concentration Pathways (RCPs were used for the future projection. Aerosol loading in the atmosphere has already peaked and is now reducing in Europe and North America. However, in Asia where rapid economic growth is ongoing, aerosol loading is estimated to reach a maximum in the first half of this century. Atmospheric aerosols originating from the burning of biomass have maintained high loadings throughout the 21st century in Africa, according to the RCPs. Evolution of the adjusted forcing by direct and indirect aerosol effects over time generally correspond to the aerosol loading. The probable future pathways of global mean forcing differ based on the aerosol direct effect for different RCPs. Because aerosol forcing will be close to the preindustrial level by the end of the 21st century for all RCPs despite the continuous increases in greenhouse gases, global warming will be accelerated with reduced aerosol negative forcing.

  12. Synthetic Scenarios from CMIP5 Model Simulations for Climate Change Impact Assessments in Managed Ecosystems and Water Resources: Case Study in South Asian Countries

    Science.gov (United States)

    Anandhi, A.; Omani, N.; Chaubey, I.; Horton, R.; Bader, D.; Nanjundiah, R. S.

    2017-01-01

    Increasing population, urbanization, and associated demand for food production compounded by climate change and variability have important implications for the managed ecosystems and water resources of a region. This is particularly true for south Asia, which supports one quarter of the global population, half of whom live below the poverty line. This region is largely dependent on monsoon precipitation for water. Given the limited resources of the developing countries in this region, the objective of our study was to empirically explore climate change in south Asia up to the year 2099 using monthly simulations from 35 global climate models (GCMs) participating in the fifth phase of the Climate Model Inter-comparison Project (CMIP5) for two future emission scenarios (representative concentration pathways RCP4.5 and RCP8.5) and provide a wide range of potential climate change outcomes. This was carried out using a three-step procedure: calculating the mean annual, monsoon, and non-monsoon precipitation and temperatures; estimating the percent change from historical conditions; and developing scenario funnels and synthetic scenarios. This methodology was applied for the entire south Asia region; however, the percent change information generated at 1.5deg grid scale can be used to generate scenarios at finer spatial scales. Our results showed a high variability in the future change in precipitation (-23% to 52%, maximum in the non-monsoon season) and temperature (0.8% to 2.1%) in the region. Temperatures in the region consistently increased, especially in the Himalayan region, which could have impacts including a faster retreat of glaciers and increased floods. It could also change rivers from perennial to seasonal, leading to significant challenges in water management. Increasing temperatures could further stress groundwater reservoirs, leading to withdrawal rates that become even more unsustainable. The high precipitation variability (with higher propensity for

  13. Köppen bioclimatic evaluation of CMIP historical climate simulations

    Science.gov (United States)

    Phillips, Thomas J.; Bonfils, Céline J. W.

    2015-06-01

    Köppen bioclimatic classification relates generic vegetation types to characteristics of the interactive annual-cycles of continental temperature (T) and precipitation (P). In addition to predicting possible bioclimatic consequences of past or prospective climate change, a Köppen scheme can be used to pinpoint biases in model simulations of historical T and P. In this study a Köppen evaluation of Coupled Model Intercomparison Project (CMIP) simulations of historical climate is conducted for the period 1980-1999. Evaluation of an example CMIP5 model illustrates how errors in simulating Köppen vegetation types (relative to those derived from observational reference data) can be deconstructed and related to model-specific temperature and precipitation biases. Measures of CMIP model skill in simulating the reference Köppen vegetation types are also developed, allowing the bioclimatic performance of a CMIP5 simulation of T and P to be compared quantitatively with its CMIP3 antecedent. Although certain bioclimatic discrepancies persist across model generations, the CMIP5 models collectively display an improved rendering of historical T and P relative to their CMIP3 counterparts. In addition, the Köppen-based performance metrics are found to be quite insensitive to alternative choices of observational reference data or to differences in model horizontal resolution.

  14. Climatic effects of irrigation over the Huang-Huai-Hai Plain in China simulated by the weather research and forecasting model: Simulated Irrigation Effects in China

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Ben [CMA-NJU Joint Laboratory for Climate Prediction Studies, Institute for Climate and Global Change Research, School of Atmospheric Sciences, Nanjing China; Collaborative Innovation Center of Climate Change, Jiangsu Province China; Zhang, Yaocun [CMA-NJU Joint Laboratory for Climate Prediction Studies, Institute for Climate and Global Change Research, School of Atmospheric Sciences, Nanjing China; Collaborative Innovation Center of Climate Change, Jiangsu Province China; Qian, Yun [Pacific Northwest National Laboratory, Richland Washington USA; Tang, Jian [China Meteorological Administration, Beijing China; Liu, Dongqing [Nanjing Meteorological Bureau, Nanjing China

    2016-03-14

    In this study, we apply the Weather Research and Forecasting model coupled with an operational-like irrigation scheme to investigate the climatic effects of irrigation over the Huang-Huai-Hai plain (3HP) in China. Multiple numerical experiments with irrigation off/on during spring, summer and both spring and summer are conducted, respectively. Our results show that the warm bias in surface temperature and dry bias in soil moisture are reduced over the 3HP region during growing seasons when irrigation is turned on in the model. Air temperature during non-growing seasons is also affected by irrigation due to the persistent effects of soil moisture on land-air energy exchanges and ground heat storage. Irrigation can induce a cooler planetary boundary layer (PBL) during growing seasons, causing a wetter PBL with more low-level clouds during spring but relatively dryer PBL in summer. Further analyses indicate that the dryer summer is highly related to the changes in the East Asian summer monsoon (EASM) circulation that is modified by irrigation effect. Spring irrigation may induce a decreased land-ocean thermal contrast, leading to a possible weaker EASM. Summer irrigation, however, evidently cools the atmosphere column and forces a southward shift of the upper-level jet, which results in more precipitation in Yangtze River basin but less over southern and northern China during summer.

  15. Wave climate of the Adriatic Sea: a future scenario simulation

    Directory of Open Access Journals (Sweden)

    A. Benetazzo

    2012-06-01

    Full Text Available We present a study on expected wind wave severity changes in the Adriatic Sea for the period 2070–2099 and their impact on extremes. To do so, the phase-averaged spectral wave model SWAN is forced using wind fields computed by the high-resolution regional climate model COSMO-CLM, the climate version of the COSMO meteorological model downscaled from a global climate model running under the IPCC-A1B emission scenario. Namely, the adopted wind fields are given with a horizontal resolution of 14 km and 40 vertical levels, and they are prepared by the Italian Aerospace Research Centre (CIRA. Firstly, in order to infer the wave model accuracy in predicting seasonal variability and extreme events, SWAN results are validated against a control simulation, which covers the period 1965–1994. In particular, numerical predictions of the significant wave height Hs are compared against available in-situ data. Further, a statistical analysis is carried out to estimate changes on wave storms and extremes during the simulated periods (control and future scenario simulations. In particular, the generalized Pareto distribution is used to predict changes of storm peak Hs for frequent and rare storms in the Adriatic Sea. Finally, Borgman's theory is applied to estimate the spatial pattern of the expected maximum wave height Hmax during a storm, both for the present climate and that of the future scenario. Results show a future wave climate in the Adriatic Sea milder than the present climate, even though increases of wave severity can occur locally.

  16. Zonda downslope winds in the central Andes of South America in a 20-year climate simulation with the Eta model

    Science.gov (United States)

    Antico, Pablo L.; Chou, Sin Chan; Mourão, Caroline

    2015-12-01

    The Zonda wind is a local version of the alpine foehn in the central Andes Mountains in South America. It blows on the eastern slopes and produces an extremely warm and dry condition in Argentina. In this study, the occurrence of Zonda wind events during a 20-year simulation from the regional Eta model is analyzed and results are compared to previous studies of Zonda wind events based on weather observations. We define a set of parameters to account for the zonal pressure gradient across the mountain, vertical movement, and air humidity typical of Zonda wind events. These parameters are applied to characterize Zonda wind events in model run and to classify them as surface-level or high-level episodes. The resulting annual distribution of Zonda occurrences based on composite analyses shows a preference for winter and spring with rare occurrences during summer. For the surface-level Zonda wind events, the highest frequency occurs during spring. Whereas surface-level Zonda wind episodes more commonly initiate in the afternoon, high-level Zonda wind events show no preference for a given initiation time. Our results are mostly in agreement with previous observational results.

  17. Climate change in Central America and Mexico: regional climate model validation and climate change projections

    Energy Technology Data Exchange (ETDEWEB)

    Karmalkar, Ambarish V. [University of Oxford, School of Geography and the Environment, Oxford (United Kingdom); Bradley, Raymond S. [University of Massachusetts, Department of Geosciences, Amherst, MA (United States); Diaz, Henry F. [NOAA/ESRL/CIRES, Boulder, CO (United States)

    2011-08-15

    Central America has high biodiversity, it harbors high-value ecosystems and it's important to provide regional climate change information to assist in adaptation and mitigation work in the region. Here we study climate change projections for Central America and Mexico using a regional climate model. The model evaluation shows its success in simulating spatial and temporal variability of temperature and precipitation and also in capturing regional climate features such as the bimodal annual cycle of precipitation and the Caribbean low-level jet. A variety of climate regimes within the model domain are also better identified in the regional model simulation due to improved resolution of topographic features. Although, the model suffers from large precipitation biases, it shows improvements over the coarse-resolution driving model in simulating precipitation amounts. The model shows a dry bias in the wet season and a wet bias in the dry season suggesting that it's unable to capture the full range of precipitation variability. Projected warming under the A2 scenario is higher in the wet season than that in the dry season with the Yucatan Peninsula experiencing highest warming. A large reduction in precipitation in the wet season is projected for the region, whereas parts of Central America that receive a considerable amount of moisture in the form of orographic precipitation show significant decreases in precipitation in the dry season. Projected climatic changes can have detrimental impacts on biodiversity as they are spatially similar, but far greater in magnitude, than those observed during the El Nino events in recent decades that adversely affected species in the region. (orig.)

  18. Climate change in Central America and Mexico: regional climate model validation and climate change projections

    Science.gov (United States)

    Karmalkar, Ambarish V.; Bradley, Raymond S.; Diaz, Henry F.

    2011-08-01

    Central America has high biodiversity, it harbors high-value ecosystems and it's important to provide regional climate change information to assist in adaptation and mitigation work in the region. Here we study climate change projections for Central America and Mexico using a regional climate model. The model evaluation shows its success in simulating spatial and temporal variability of temperature and precipitation and also in capturing regional climate features such as the bimodal annual cycle of precipitation and the Caribbean low-level jet. A variety of climate regimes within the model domain are also better identified in the regional model simulation due to improved resolution of topographic features. Although, the model suffers from large precipitation biases, it shows improvements over the coarse-resolution driving model in simulating precipitation amounts. The model shows a dry bias in the wet season and a wet bias in the dry season suggesting that it's unable to capture the full range of precipitation variability. Projected warming under the A2 scenario is higher in the wet season than that in the dry season with the Yucatan Peninsula experiencing highest warming. A large reduction in precipitation in the wet season is projected for the region, whereas parts of Central America that receive a considerable amount of moisture in the form of orographic precipitation show significant decreases in precipitation in the dry season. Projected climatic changes can have detrimental impacts on biodiversity as they are spatially similar, but far greater in magnitude, than those observed during the El Niño events in recent decades that adversely affected species in the region.

  19. Modeling of Past Climates: Some Perspectives

    Science.gov (United States)

    Kutzbach, J. E.

    2008-12-01

    variability and abrupt change. Another huge challenge will be to represent, with the climate models, the processes that create the environmental records of past climate: if that goal is reached, then the 'output' of the model will be simulated environmental records that can, in turn, be compared directly to observed environmental records. In most cases, that kind of comparison of simulations and observations isn't possible now. What's past is prologue.

  20. Nitrate fluxes to groundwater under citrus orchards in a Mediterranean climate: observations, calibrated models, simulations and agro-hydrological conclusions.

    Science.gov (United States)

    Kurtzman, Daniel; Shapira, Roi H; Bar-Tal, Asher; Fine, Pinchas; Russo, David

    2013-08-01

    Nitrate contamination of groundwater under land used for intensive-agriculture is probably the most worrisome agro-hydrological sustainability problem worldwide. Vadose-zone samples from 0 to 9 m depth under citrus orchards overlying an unconfined aquifer were analyzed for variables controlling water flow and the fate and transport of nitrogen fertilizers. Steady-state estimates of water and NO3-N fluxes to groundwater were found to vary spatially in the ranges of 90-330 mm yr(-1) and 50-220 kg ha(-1) yr(-1), respectively. Calibration of transient models to two selected vadose-zone profiles required limiting the concentration of NO3-N in the solution that is taken up by the roots to 30 mg L(-1). Results of an independent lysimeter experiment showed a similar nitrogen-uptake regime. Simulations of past conditions revealed a significant correlation between NO3-N flux to groundwater and the previous year's precipitation. Simulations of different nitrogen-application rates showed that using half of the nitrogen fertilizer added to the irrigation water by farmers would reduce average NO3-N flux to groundwater by 70%, decrease root nitrogen uptake by 20% and reduce the average pore water NO3-N concentration in the deep vadose zone to below the Israeli drinking water standard; hence this rate of nitrogen application was found to be agro-hydrologically sustainable. Beyond the investigation of nitrate fluxes to groundwater under citrus orchards and the interesting case-study aspects, this work demonstrates a methodology that enables skillful decisions concerning joint sustainability of both the water resource and agricultural production in a common environmental setting.

  1. Observationally-Based Data/Model Metrics from the Southern Ocean Climate Model Atlas

    Science.gov (United States)

    Abell, J.; Russell, J. L.; Goodman, P. J.

    2015-12-01

    The Southern Ocean Climate Model Atlas makes available observationally-based standardized data/model metrics of the latest simulations of climate and projections of climate change from available climate models. Global climate model simulations differ greatly in the Southern Ocean, so the development of consistent, observationally-based metrics, by which to assess the fidelity of model simulations is essential. We will present metrics showing and quantifying the results of the modern day climate simulations over the Southern Ocean from models submitted as part of the CMIP5/IPCC-AR5 process. Our analysis will focus on the simulations of the temperature, salinity and carbon at various depths and along significant hydrographic sections. The models exhibit different skill levels with various metrics between models and also within individual models.

  2. MODIS land cover uncertainty in regional climate simulations

    Science.gov (United States)

    Li, Xue; Messina, Joseph P.; Moore, Nathan J.; Fan, Peilei; Shortridge, Ashton M.

    2017-02-01

    MODIS land cover datasets are used extensively across the climate modeling community, but inherent uncertainties and associated propagating impacts are rarely discussed. This paper modeled uncertainties embedded within the annual MODIS Land Cover Type (MCD12Q1) products and propagated these uncertainties through the Regional Atmospheric Modeling System (RAMS). First, land cover uncertainties were modeled using pixel-based trajectory analyses from a time series of MCD12Q1 for Urumqi, China. Second, alternative land cover maps were produced based on these categorical uncertainties and passed into RAMS. Finally, simulations from RAMS were analyzed temporally and spatially to reveal impacts. Our study found that MCD12Q1 struggles to discriminate between grasslands and croplands or grasslands and barren in this study area. Such categorical uncertainties have significant impacts on regional climate model outputs. All climate variables examined demonstrated impact across the various regions, with latent heat flux affected most with a magnitude of 4.32 W/m2 in domain average. Impacted areas were spatially connected to locations of greater land cover uncertainty. Both biophysical characteristics and soil moisture settings in regard to land cover types contribute to the variations among simulations. These results indicate that formal land cover uncertainty analysis should be included in MCD12Q1-fed climate modeling as a routine procedure.

  3. Simulation of Room Climate of Public Buildings

    Directory of Open Access Journals (Sweden)

    Prorokova Maria

    2016-01-01

    Full Text Available The article presents the details of modeling of heat exchange and mass transfer in a room in the formation of a microclimate. The mathematical model is implemented in the program ANSYS Fluent and is used to predict the climate parameters after the implementation of energy saving measures in the building. Verification of the mathematical model by comparing the experimental data with the results of the measurement of microclimate parameters of the experiment.

  4. Quantifying the role of biosphere-atmosphere feedbacks in climate change: coupled model simulations for 6000 years BP and comparison with palaeodata for northern Eurasia and northern Africa

    Energy Technology Data Exchange (ETDEWEB)

    Texier, D.; de Noblet, N. [CEA Saclay, Gif-sur-Yvette (France). Lab. de Modelisation du Climat et de l`Environnement; Harrison, S.P.; Laarif, F. [Dynamic Palaeoclimatology, Lund University, Box 117, S-221 00 Lund (Sweden); Haxeltine, A. [Physical Geography, Lund University, S-22100 Lund (Sweden); Jolly, D.; Prentice, I.C. [Global Systems Group, Department of Ecology, Ecology Building, S-223 b2 Lund (Sweden); Joussaume, S. [CEA Saclay, Gif-sur-Yvette (France). Lab. de Modelisation du Climat et de l`Environnement]|[Laboratoire d`Oceanographie Dynamique et de Climatologie, CNRS/ORSTOM/UPCM, Paris (France); Tarasov, P. [Dynamic Palaeoclimatology, Lund University, Box 117, S-221 00 Lund (Sweden)]|[Department of Geography, Moscow State University, 119 899 Moscow (Russian Federation)

    1997-12-01

    The LMD AGCM was iteratively coupled to the global BIOME1 model in order to explore the role of vegetation-climate interactions in response to mid-Holocene (6000 y BP) orbital forcing. The sea-surface temperature and sea-ice distribution used were present-day and CO{sub 2} concentration was preindustrial. The land surface was initially prescribed with present-day vegetation. Initial climate ``anomalies`` (differences between AGCM results for 6000 y BP and control) were used to drive BIOME1; the simulated vegetation was provided to a further AGCM run, and so on. Results after five iterations were compared to the initial results in order to identify vegetation feedbacks. These were centred on regions showing strong initial responses. The orbitally induced high-latitude summer warming, and the intensification and extension of Northern Hemisphere tropical monsoons, were both amplified by vegetation feedbacks. Vegetation feedbacks were smaller than the initial orbital effects for most regions and seasons, but in West Africa the summer precipitation increase more than doubled in response to changes in vegetation. In the last iteration, global tundra area was reduced by 25% and the southern limit of the Sahara desert was shifted 2.5 N north (to 18 N) relative to today. These results were compared with 6000 y BP observational data recording forest-tundra boundary changes in northern Eurasia and savana-desert boundary changes in northern Africa. Although the inclusion of vegetation feedbacks improved the qualitative agreement between the model results and the data, the simulated changes were still insufficient, perhaps due to the lack of ocean-surface feedbacks. (orig.) With 8 figs., 4 tabs., 80 refs.

  5. Numerical Simulation of Long-Term Climate Change in East Asia

    Institute of Scientific and Technical Information of China (English)

    TANG Jianping; SU Bingkai; ZHAO Ming; ZHAO Deming

    2006-01-01

    A 10-yr regional climate simulation was performed using the fifth-generation PSU/NCAR Mesoscale Model Version 3 (MM5V3) driven by large-scale NCEP/NCAR reanalyses. Simulations of winter and summer mean regional climate features were examined against observations. The results showed that the model could well simulate the 10-yr winter and summer mean circulation, temperature, and moisture transport at middle and low levels. The simulated winter and summer mean sea level pressure agreed with the NCAR/NCEP reanalysis data. The model could well simulate the distribution and intensity of winter mean precipitation rates as well as the distribution of summer mean precipitation rates, but it overestimated the summer mean precipitation over North China. The model's ability to simulate the regional climate change in winter was superior to that in summer. In addition, the model could simulate the inter-annual variation of seasonal precipitation and surface air temperature. Geopotential heights and temperature at middle and high levels between simulations and observations exhibited high anomaly correlation coefficients. The model also showed large variability to simulate the regional climate change associated with the El Nino events. The MM5V3 well simulated the anomalies of summer mean precipitation in 1992 and 1995, while it demonstrated much less ability to simulate that in 1998. Generally speaking, the MM5V3 is capable of simulating the regional climate change, and could be used for long-term regional climate simulation.

  6. Evaluation of moisture sources of the Central European summer flood of May/June 2013 based on an ensemble of regional climate model simulations

    Science.gov (United States)

    Kelemen, Fanni D.; Ludwig, Patrick; Reyers, Mark; Ulbrich, Sven; Pinto, Joaquim G.

    2015-04-01

    In May/June 2013, heavy precipitation hit Central Europe, triggering damaging floods both on the Danube and on Elbe basins. In this study, we perform a detailed analysis of the synoptic development of the event based on an ensemble of regional climate model simulations performed with the COSMO-CLM. Simulations are performed with reanalysis data boundary conditions in multiple set-ups and horizontal resolutions of 0.375° and 0.125°. In particular, the aim is to identify potential moisture sources, and how they contributed to the event quantitatively. A control simulation with undisturbed (reanalysis) boundary conditions and sensitivity experiments with modified evaporation characteristics are performed to distinguish the role of moisture evaporated from marine and land areas. To keep the structure of the simulations close to reality as possible, spectral nudging is applied on the upper level atmospheric wind fields. For all simulations, the synoptic situations and cyclone tracks are evaluated against an independent reanalysis dataset, and simulated precipitation amounts are validated against E-OBS precipitation data. In general, the upper level atmospheric characteristics, which trigger the cyclones, are similar in the simulations compared to the reanalysis. Moreover, the time evolution of the precipitation event is well simulated. Nevertheless there are some differences in the spatial and temporal distribution of the precipitation. In both, the reanalysis and the control simulation, the cyclones relevant for this event were moving westward (retrograde movement), counterclockwise from the Mediterranean region over Eastern Europe towards the northern slopes of the Alps. The pre-existing moist soil over East and Central Europe and the circulation associated with the cyclones contributed to intense evapotranspiration, and thus the westward propagating cyclones brought a lot of moisture along their tracks towards Central Europe. The sensitivity studies performed with

  7. Tsengwen Reservoir Watershed Hydrological Flood Simulation Under Global Climate Change Using the 20 km Mesh Meteorological Research Institute Atmospheric General Circulation Model (MRI-AGCM

    Directory of Open Access Journals (Sweden)

    Nobuaki Kimura

    2014-01-01

    Full Text Available Severe rainstorms have occurred more frequently in Taiwan over the last decade. To understand the flood characteristics of a local region under climate change, a hydrological model simulation was conducted for the Tsengwen Reservoir watershed. The model employed was the Integrated Flood Analysis System (IFAS, which has a conceptual, distributed rainfall-runoff analysis module and a GIS data-input function. The high-resolution rainfall data for flood simulation was categorized into three terms: 1979 - 2003 (Present, 2015 - 2039 (Near-future, and 2075 - 2099 (Future, provided by the Meteorological Research Institute atmospheric general circulation model (MRI-AGCM. Ten extreme rainfall (top ten events were selected for each term in descending order of total precipitation volume. Due to the small watershed area the MRI-AGCM3.2S data was downsized into higher resolution data using the Weather Research and Forecasting Model. The simulated discharges revealed that most of the Near-future and Future peaks caused by extreme rainfall increased compared to the Present peak. These ratios were 0.8 - 1.6 (Near-future/Present and 0.9 - 2.2 (Future/Present, respectively. Additionally, we evaluated how these future discharges would affect the reservoir¡¦s flood control capacity, specifically the excess water volume required to be stored while maintaining dam releases up to the dam¡¦s spillway capacity or the discharge peak design for flood prevention. The results for the top ten events show that the excess water for the Future term exceeded the reservoir¡¦s flood control capacity and was approximately 79.6 - 87.5% of the total reservoir maximum capacity for the discharge peak design scenario.

  8. Steric Sea Level Change in Twentieth Century Historical Climate Simulation and IPCC-RCP8.5 Scenario Projection: A Comparison of Two Versions of FGOALS Model

    Institute of Scientific and Technical Information of China (English)

    DONG Lu; ZHOU Tianjun

    2013-01-01

    To reveal the steric sea level change in 20th century historical climate simulations and future climate change projections under the IPCC's Representative Concentration Pathway 8.5 (RCP8.5) scenario,the results of two versions of LASG/IAP's Flexible Global Ocean-Atmosphere-Land System model (FGOALS) are analyzed.Both models reasonably reproduce the mean dynamic sea level features,with a spatial pattern correlation coefficient of 0.97 with the observation.Characteristics of steric sea level changes in the 20th century historical climate simulations and RCP8.5 scenario projections are investigated.The results show that,in the 20th century,negative trends covered most parts of the global ocean.Under the RCP8.5 scenario,global-averaged steric sea level exhibits a pronounced rising trend throughout the 21st century and the general rising trend appears in most parts of the global ocean.The magnitude of the changes in the 21st century is much larger than that in the 20th century.By the year 2100,the global-averaged steric sea level anomaly is 18 cm and 10 cm relative to the year 1850 in the second spectral version of FGOALS (FGOALS-s2) and the second grid-point version of FGOALS (FGOALS-g2),respectively.The separate contribution of the thermosteric and halosteric components from various ocean layers is further evaluated.In the 20th century,the steric sea level changes in FGOALS-s2 (FGOALS-g2) are largely attributed to the thermosteric (halosteric) component relative to the pre-industrial control run.In contrast,in the 21st century,the thermosteric component,mainly from the upper 1000 m,dominates the steric sea level change in both models under the RCP8.5 scenario.In addition,the steric sea level change in the marginal sea of China is attributed to the thermosteric component.

  9. Construction of a novel economy-climate model

    Institute of Scientific and Technical Information of China (English)

    CHOU JieMing; DONG WenJie; YE DuZheng

    2007-01-01

    An attempt has been made to construct a novel economy-climate model by combining climate change research with agricultural economy research to evaluate the influence of global climate change on grain yields. The insertion of a climate change factor into the economic C-D (Cobb-Dauglas) production function model yields a novel evaluation model, which connects the climate change factor to the economic variation factor, and the performance and reasonableness of the novel evaluation model are also preliminarily simulated and verified.

  10. Impact of high resolution land surface initialization in Indian summer monsoon simulation using a regional climate model

    Indian Academy of Sciences (India)