WorldWideScience

Sample records for aqua modis reflectance

  1. On-orbit performance and calibration improvements for the reflective solar bands of Terra and Aqua MODIS

    Science.gov (United States)

    Angal, Amit; Xiong, Xiaoxiong (Jack); Wu, Aisheng; Chen, Hongda; Geng, Xu; Link, Daniel; Li, Yonghong; Wald, Andrew; Brinkmann, Jake

    2016-05-01

    Moderate Resolution Imaging Spectroradiometer (MODIS) is the keystone instrument for NASA's EOS Terra and Aqua missions, designed to extend and improve heritage sensor measurements and data records of the land, oceans and atmosphere. The reflective solar bands (RSB) of MODIS covering wavelengths from 0.41 μm to 2.2 μm, are calibrated on-orbit using a solar diffuser (SD), with its on-orbit bi-directional reflectance factor (BRF) changes tracked using a solar diffuser stability monitor (SDSM). MODIS is a scanning radiometer using a two-sided paddle-wheel mirror to collect earth view (EV) data over a range of +/-55° off instrument nadir. In addition to the solar calibration provided by the SD and SDSM system, lunar observations at nearly constant phase angles are regularly scheduled to monitor the RSB calibration stability. For both Terra and Aqua MODIS, the SD and lunar observations are used together to track the on-orbit changes of RSB response versus scan angle (RVS) as the SD and SV port are viewed at different angles of incidence (AOI) on the scan mirror. The MODIS Level 1B (L1B) Collection 6 (C6) algorithm incorporated several enhancements over its predecessor Collection 5 (C5) algorithm. A notable improvement was the use of the earth-view (EV) response trends from pseudo-invariant desert targets to characterize the on-orbit RVS for select RSB (Terra bands 1-4, 8, 9 and Aqua bands 8, 9) and the time, AOI, and wavelength-dependent uncertainty. The MODIS Characterization Support Team (MCST) has been maintaining and enhancing the C6 algorithm since its first update in November, 2011 for Aqua MODIS, and February, 2012 for Terra MODIS. Several calibration improvements have been incorporated that include extending the EV-based RVS approach to other RSB, additional correction for SD degradation at SWIR wavelengths, and alternative approaches for on-orbit RVS characterization. In addition to the on-orbit performance of the MODIS RSB, this paper also discusses in

  2. MODIS/AQUA MYD09Q1 Surface Reflectance 8-Day L3 Global 250m

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The MODIS Surface Reflectance products provide an estimate of the surface spectral reflectance as it would be measured at ground level in the absence of atmospheric...

  3. MODIS/AQUA MYD09GQ Surface Reflectance Daily L2G Global 250m

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The MODIS Surface Reflectance products provide an estimate of the surface spectral reflectance as it would be measured at ground level in the absence of atmospheric...

  4. MODIS/AQUA MYD09A1 Surface Reflectance 8-Day L3 Global 500m

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The MODIS Surface Reflectance products provide an estimate of the surface spectral reflectance as it would be measured at ground level in the absence of atmospheric...

  5. Remote Sensing Reflectance at 667 nm , Aqua MODIS, NPP, 0.125 degrees, Gulf of Mexico

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — MODIS measures the remote sensing reflectance (Rrs) at 667nm. This can be used to view very high concentrations of phytoplankton in the very surface of the water.

  6. MODIS/AQUA MYD09CMG Surface Reflectance Daily L3 Global 0.05Deg CMG

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The MODIS Surface Reflectance products provide an estimate of the surface spectral reflectance as it would be measured at ground level in the absence of atmospheric...

  7. MODIS/AQUA MYD09GA Surface Reflectance Daily L2G Global 1km and 500m Version 6

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The MODIS Surface Reflectance products provide an estimate of the surface spectral reflectance as it would be measured at ground level in the absence of atmospheric...

  8. MODIS/AQUA MYD09CMG Surface Reflectance Daily L3 Global 0.05Deg CMG Version 6

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The MODIS Surface Reflectance products provide an estimate of the surface spectral reflectance as it would be measured at ground level in the absence of atmospheric...

  9. MODIS/AQUA MYD09GA Surface Reflectance Daily L2G Global 1km and 500m

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The MODIS Surface Reflectance products provide an estimate of the surface spectral reflectance as it would be measured at ground level in the absence of atmospheric...

  10. MODIS/AQUA MYD09A1 Surface Reflectance 8-Day L3 Global 500m Version 6

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The MODIS Surface Reflectance products provide an estimate of the surface spectral reflectance as it would be measured at ground level in the absence of atmospheric...

  11. MODIS/AQUA MYD09Q1 Surface Reflectance 8-Day L3 Global 250m Version 6

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The MODIS Surface Reflectance products provide an estimate of the surface spectral reflectance as it would be measured at ground level in the absence of atmospheric...

  12. MODIS/AQUA MYD09GQ Surface Reflectance Daily L2G Global 250m Version 6

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The MODIS Surface Reflectance products provide an estimate of the surface spectral reflectance as it would be measured at ground level in the absence of atmospheric...

  13. Summary of Terra and Aqua MODIS Long-Term Performance

    Science.gov (United States)

    Xiong, Xiaoxiong (Jack); Wenny, Brian N.; Angal, Amit; Barnes, William; Salomonson, Vincent

    2011-01-01

    Since launch in December 1999, the MODIS ProtoFlight Model (PFM) onboard the Terra spacecraft has successfully operated for more than 11 years. Its Flight Model (FM) onboard the Aqua spacecraft, launched in May 2002, has also successfully operated for over 9 years. MODIS observations are made in 36 spectral bands at three nadir spatial resolutions and are calibrated and characterized regularly by a set of on-board calibrators (OBC). Nearly 40 science products, supporting a variety of land, ocean, and atmospheric applications, are continuously derived from the calibrated reflectances and radiances of each MODIS instrument and widely distributed to the world-wide user community. Following an overview of MODIS instrument operation and calibration activities, this paper provides a summary of both Terra and Aqua MODIS long-term performance. Special considerations that are critical to maintaining MODIS data quality and beneficial for future missions are also discussed.

  14. MYDOCGA: MODIS/Aqua Ocean Reflectance Daily L2G-Lite Global 1 km SIN Grid Version 6

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The Version 6 Level 2 Gridded (L2G) Ocean Reflectance product consists of 1 kilometer reflectance data from MODIS bands 8-16. The product is referred to as ocean...

  15. Comparison of Reflected Solar Radiance Using Aqua Modis and Airborne Remote Sensing (case : Deep Convective Clouds and Cirrus Clouds)

    Science.gov (United States)

    Krisna, T. C.; Ehrlich, A.; Werner, F.; Wendisch, M.

    2015-12-01

    Deep Convective Clouds (DCCs) have key role in the tropical region. Despite they only have small spatial coverage, but they account most of the total precipitation in these region which often make flooding. There are such of aviation accidents caused by strong vertical wind, hailing, icing and lightning inside the clouds. Pollutions caused by biomass burning and land degradation can change the aerosol properties as well as cloud properties, therefore will influence the radiation and formation of the DCCs. Those are the major reasons that better understanding of DCCs formation and life cycle are necessary. Between Sept. 01 - Oct. 14, ACRIDICON (Aerosol, Cloud, Precipitation, and Radiation Interactions and Dynamics of Concevtive Clouds Systems) campaign was conducted over Amazonia. It is suitable area to be the site-study due to has strong contrast environtment (pristine and polluted), regular convection activities and stable meteorological condition. In this study we focus on the 2 satellite validation missions designed to fly collocated but in different altitude with A-TRAIN constellation. In order to study DCCs-solar radiation interaction, we use SMART (Spectral Modular Airborne Radiation Measurements System) installed on HALO (High Altitude and Long-Range Research Aircraft) which measures spectral Irradiance (F) and Radiance (I) at the wavelength between 300-2200 nm corresponding to satellite. Due to the limitation in spatial and temporal, airborne measurements only give snapshots of atmosphere condition and DCCs formation, therefore we use multi-satellite data as DCCs have high vertical and horizontal distance, long temporal development and complex form. The comparison of AQUA MODIS and SMART Radiance at 645 nm (non-absorbing) in the clear-sky condition gives strong agreement, but in the multilayer-cloud condition gives worse and results in high underestimation (-86%) in SMART data especially at lower altitude. The bias is caused by interference from clouds

  16. Corrections to the MODIS Aqua Calibration Derived From MODIS Aqua Ocean Color Products

    Science.gov (United States)

    Meister, Gerhard; Franz, Bryan Alden

    2013-01-01

    Ocean color products such as, e.g., chlorophyll-a concentration, can be derived from the top-of-atmosphere radiances measured by imaging sensors on earth-orbiting satellites. There are currently three National Aeronautics and Space Administration sensors in orbit capable of providing ocean color products. One of these sensors is the Moderate Resolution Imaging Spectroradiometer (MODIS) on the Aqua satellite, whose ocean color products are currently the most widely used of the three. A recent improvement to the MODIS calibration methodology has used land targets to improve the calibration accuracy. This study evaluates the new calibration methodology and describes further calibration improvements that are built upon the new methodology by including ocean measurements in the form of global temporally averaged water-leaving reflectance measurements. The calibration improvements presented here mainly modify the calibration at the scan edges, taking advantage of the good performance of the land target trending in the center of the scan.

  17. Early on-orbit calibration results from Aqua MODIS

    Science.gov (United States)

    Xiong, Xiaoxiong; Barnes, William L.

    2003-04-01

    Aqua MODIS, also known as the MODIS Flight Model 1 (FM1), was launched on May 4, 2002. It opened its nadir aperture door (NAD) on June 24, 2002, beginning its Earth observing mission. In this paper, we present early results from Aqua MODIS on-orbit calibration and characterization and assess the instrument's overall performance. MODIS has 36 spectral bands located on four focal plane assemblies (FPAs). Bands 1-19, and 26 with wavelengths from 0.412 to 2.1 microns are the reflective solar bands (RSB) that are calibrated on-orbit by a solar diffuser (SD). The degradation of the SD is tracked using a solar diffuser stability monitor (SDSM). The bands 20-25, and 27-36 with wavelengths from 3.75 to 14.5 microns are the thermal emissive bands (TEB) that are calibrated on-orbit by a blackbody (BB). Early results indicate that the on-orbit performance has been in good agreement with the predications determined from pre-launch measurements. Except for band 21, the low gain fire band, band 6, known to have some inoperable detectors from pre-launch characterization, and one noisy detector in band 36, all of the detectors' noise characterizations are within their specifications. Examples of the sensor's short-term and limited long-term responses in both TEB and RSB will be provided to illustrate the sensor's on-orbit stability. In addition, we will show some of the improvements that Aqua MODIS made over its predecessor, Terra MODIS (Protoflight Model - PFM), such as removal of the optical leak into the long-wave infrared (LWIR) photoconductive (PC) bands and reduction of electronic crosstalk and out-of-band (OOB) thermal leak into the short-wave infrared (SWIR) bands.

  18. SST, Aqua MODIS, NPP, 0.0125 degrees, Indonesia, Daytime

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA CoastWatch provides SST data from NASA's Aqua Spacecraft. Measurements are gathered by the Moderate Resolution Imaging Spectroradiometer (MODIS) carried aboard...

  19. Cross-calibration of the Oceansat-2 Ocean Colour Monitor (OCM) with Terra and Aqua MODIS

    Science.gov (United States)

    Angal, Amit; Brinkmann, Jake; Kumar, A. Senthil; Xiong, Xiaoxiong

    2016-05-01

    The Ocean Colour Monitor (OCM) sensor on-board the Oceansat-2 spacecraft has been operational since its launch in September, 2009. The Oceansat 2 OCM primary design goal is to provide continuity to Oceansat-1 OCM to obtain information regarding various ocean-colour variables. OCM acquires Earth scene measurements in eight multi-spectral bands in the range from 402 to 885 nm. The MODIS sensor on the Terra and Aqua spacecraft has been successfully operating for over a decade collecting measurements of the earth's land, ocean surface and atmosphere. The MODIS spectral bands, designed for land and ocean applications, cover the spectral range from 412 to 869 nm. This study focuses on comparing the radiometric calibration stability of OCM using near-simultaneous TOA measurements with Terra and Aqua MODIS acquired over the Libya 4 target. Same-day scene-pairs from all three sensors (OCM, Terra and Aqua MODIS) between August, 2014 and September, 2015 were chosen for this analysis. On a given day, the OCM overpass is approximately an hour after the Terra overpass and an hour before the Aqua overpass. Due to the orbital differences between Terra and Aqua, MODIS images the Libya 4 site at different scan-angles on a given day. Some of the high-gain ocean bands for MODIS tend to saturate while viewing the bright Libya 4 target, but bands 8-10 (412 nm - 486 nm) provide an unsaturated response and are used for comparison with the spectrally similar OCM bands. All the standard corrections such as bidirectional reflectance factor (BRDF), relative spectral response mismatch, and impact for atmospheric water-vapor are applied to obtain the reflectance differences between OCM and the two MODIS instruments. Furthermore, OCM is used as a transfer radiometer to obtain the calibration differences between Terra and Aqua MODIS reflective solar bands.

  20. Retrieval of Aerosol Properties from MODIS Terra, MODIS Aqua, and VIIRS SNPP: Calibration Focus

    Science.gov (United States)

    Levy, Robert C.; Mattoo, Shana; Sawyer, Virginia; Kleidman, Richard; Patadia, Falguni; Zhou, Yaping; Gupta, Pawan; Shi, Yingxi; Remer, Lorraine; Holz, Robert

    2016-01-01

    MODIS-DT Collection 6 - Aqua/Terra level 2, 3; entire record processed - "Trending" issues reduced - Still a 15% or 0.02 Terra vs Aqua offset. - Terra/Aqua convergence improved with C6+, but bias remains. - Other calibration efforts yield mixed results. VIIRS-­-DT in development - VIIRS is similar, yet different then MODIS - With 50% wider swath, VIIRS has daily coverage - Ensures algorithm consistency with MODIS. - Currently: 20% NPP vs Aqua offset over ocean. - Only small bias (%) over land (2012-­-2016) - Can VIIRS/MODIS create aerosol CDR? Calibration for MODIS - VIIRS continues to fundamentally important. It's not just Terra, or just Aqua, or just NPP-­-VIIRS, I really want to push synergistic calibration.

  1. MODIS solar reflective calibration traceability

    Science.gov (United States)

    Xiong, Xiaoxiong; Butler, Jim

    2009-08-01

    Long-term climate data records often consist of observations made by multiple sensors. It is, therefore, extremely important to have instrument overlap, to be able to track instrument stability, to quantify measurement uncertainties, and to establish an absolute measurement scale traceable to the International System of Units (SI). The Moderate Resolution Imaging Spectroradiometer (MODIS) is a key instrument for both the Terra and Aqua missions, which were launched in December 1999 and May 2002, respectively. It has 20 reflective solar bands (RSB) with wavelengths from 0.41 to 2.2μm and observes the Earth at three nadir spatial resolutions: 0.25km, 0.5km, and 1km. MODIS RSB on-orbit calibration is reflectance based with reference to the bi-directional reflectance factor (BRF) of its on-board solar diffuser (SD). The SD BRF characterization was made pre-launch by the instrument vendor using reference samples traceable directly to the National Institute of Standards and Technology (NIST). On-orbit SD reflectance degradation is tracked by an on-board solar diffuser stability monitor (SDSM). This paper provides details of this calibration chain, from pre-launch to on-orbit operation, and associated uncertainty assessments. Using MODIS as an example, this paper also discusses challenges and key design requirements for future missions developed for accurate climate studies.

  2. MODIS Solar Reflective Calibration Traceability

    Science.gov (United States)

    Xiong, Xiaoxiong; Butler, Jim

    2009-01-01

    Long-term climate data records often consist of observations made by multiple sensors. It is, therefore, extremely important to have instrument overlap, to be able to track instrument stability, to quantify, measurement uncertainties, and to establish absolute scale traceable to the International System of Units (SI). The Moderate Resolution Imaging Spectroradiometer (MODIS) is a key instrument for both the Terra and Aqua missions, which were launched in December 1999 and May 2002, respectively. It has 20 reflective solar bands (RSB) with wavelengths from 0.41 to 2.2 micrometers and observes the Earth at three nadir spatial resolutions: 0.25km, 0.5km, and 1km. MODIS RSB on-orbit calibration is reflectance based with reference to the bidirectional reflectance factor (BRF) of its on-board solar diffuser (SD). The SD BRF characterization was made pre-launch by the instrument vendor using reference samples traceable directly to the National Institute of Standards and Technology (NIST). On-orbit SD reflectance degradation is tracked by an on-board solar diffuser monitor (SDSM). This paper provides details of this calibration chain, from prelaunch to on-orbit operation, and associated uncertainty assessments. Using MODIS as an example, this paper also discusses challenges and key design requirements for future missions developed for accurate climate studies.

  3. Moderate Resolution Imaging Spectroradiometer (MODIS) - Aqua

    Data.gov (United States)

    National Aeronautics and Space Administration — This dataset represents multiple products archived at the multiple archive centers for the MODIS (Moderate Resolution Imaging Spectroradiometer) instrument aboard...

  4. An Overview of Lunar Calibration and Characterization for the EOS Terra and Aqua MODIS

    Science.gov (United States)

    Xiong, X.; Salomonson, V. V.; Sun, J.; Chiang, K.; Xiong, S.; Humphries, S.; Barnes, W.; Guenther, B.

    2004-01-01

    The Moon can be used as a stable source for Earth-observing sensors on-orbit radiometric and spatial stability monitoring in the VIS and NIR spectral regions. It can also serve as a calibration transfer vehicle among multiple sensors. Nearly identical copies of the Moderate Resolution Imaging Spectroradiometer (MODE) have been operating on-board the NASA's Earth Observing System (EOS) Terra and Aqua satellites since their launches in December 1999 and May 2002, respectively. Terra and Aqua MODIS each make observations in 36 spectral bands covering the spectral range from 0.41 to 14.5 microns and are calibrated on-orbit by a set of on-board calibrations (OBCs) including: 1) a solar diffuser (SD), 2) a solar diffuser stability monitor (SDSM), 3) a blackbody (BB), and 4) a spectro-radiometric calibration assembly (SRCA). In addition to fully utilizing the OBCs, the Moon has been used extensively by both Terra and Aqua MODIS to support their on-orbit calibration and characterization. A 4 This paper provides an overview of applications of lunar calibration and characterization from the MODIS perspective, including monitoring radiometric calibration stability for the reflective solar bands (RSBs), tracking changes of the sensors response versus scan-angle (RVS), examining the sensors spatial performance , and characterizing optical leaks and electronic crosstalk among different spectral bands and detectors. On-orbit calibration consistency between the two MODIS instruments is also addressed. Based on the existing on-orbit time series of the Terra and Aqua MODIS lunar observations, the radiometric difference between the two sensors is less than +/-1% for the RSBs. This method provides a powerful means of performing calibration comparisons among Earth-observing sensors and assures consistent data and science products for the long-term studies of climate and environmental changes.

  5. Comparisons of Terra- and Aqua MODIS in band reflectance and vegetation index%Terra MODIS和Aqua MODIS波段反射率及植被指数比较

    Institute of Scientific and Technical Information of China (English)

    王静; 郭铌

    2008-01-01

    对Terra MODIS和Aqua MODIS之间单波段反射率及植被指数进行了比较.结果表明:Terra MODIS和Aqua MODIS单波段反射率及植被指数具有极显著的相关性,植被指数较单波段反射率相关性更高些;Terra MODIS单波段反射率值普遍较Aqua MODIS值低,而植被指数值普遍较Aqua MODIS值高;不同时段Terra MODIS和Aqua MODIS单波段反射率及植被指数间差异不同,植被指数在冬季差异最大,而单波段反射率则在夏秋季差异较大;不同植被类型Terra MODIS和Aqua MODIS间植被指数差异总体规律相似,但单波段反射率间差异较为复杂;草甸、草原无论是单波段反射率还是植被指数,Terra MODIS和AquaMODIS的差异均比其他几种植被类型小,而阔叶林和一年两熟作物则差异相对大些.

  6. Aerosol retrieval over land by exploiting the synergy of TERRA and AQUA MODIS DATA

    Institute of Scientific and Technical Information of China (English)

    TANG; Jiakui; XUE; Yong; YU; Tong; GUAN; Yanning; CAI; Guoyin

    2006-01-01

    Aerosol retrieval over land from satellite remotely sensed data remains internationally a difficult task. By using MODIS data, the Dark Dense Vegetation (DDV) algorithm aerosol distribution and properties retrieval over land has shown excellent competence. However, this algorithm is restricted to lower surface reflectance such as water bodies and dense vegetation, which limits its actual application, and is unable to be used for high reflective surface such as over urban areas. In this paper, we introduce a new aerosol retrieval model by exploiting the Synergy of TERRA and AQUA MODIS data (SYNTAM), which can be used for various ground surfaces, including for high reflective surface. Preliminary validations have been carried out by comparing with AERONET measured data, which shows good accuracy and promising potential. Further research work is undergoing.

  7. A Comparison of Cirrus Clouds Retrieved From POLDER-3/PARASOL and MODIS/Aqua

    Science.gov (United States)

    Zhang, Z.; Yang, P.; Riedi, J.; Kattawar, G.

    2007-12-01

    MODIS on board Aqua and POLDER-3 on board PARASOL are two key instruments in the A-Train constellation of satellites. MODIS has 36 spectral bands with wavelength ranging from 0.41 to 14.5 μm, but makes measurement at only one direction without information about polarization. POLDER performs multidirectional measurements, of both reflectance and polarization, at nine spectral channels (from 443 to 1020 nm). The two instruments offer different, and somehow complementary, advantages for the remote sensing of microphysical and optical properties of cirrus clouds. In this study, a comparison of cirrus clouds retrieved from the two instruments is made to obtain understanding of the possibility, advantages and limitations of synergetic retrieval. First, the comparison is made between the single scattering properties of "Inhomogeneous Hexagonal Monocrystals" (IHM) used in POLDER retrieval algorithm and the ice-crystal ensemble model used for MODIS. Substantial differences are found in the scattering phase matrix. Co-located cloud mask and cloud top height retrievals are compared, with the emphasis on high and thin cirrus clouds. The optical thicknesses of cirrus clouds retrieved by POLDER are compared with those by MODIS, with and without the constraint that the cloud effective particle size retrieved by MODIS must be similar to that of IHM.

  8. Primary Productivity, NASA Aqua MODIS, 4.4 km, Global, EXPERIMENTAL

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Primary Productivity is calculated from NASA Aqua MODIS Chl a SST data. THIS IS AN EXPERIMENTAL PRODUCT: intended strictly for scientific evaluation by professional...

  9. Debris Likelihood, based on GhostNet, NASA Aqua MODIS, and GOES Imager, EXPERIMENTAL

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Debris Likelihood Index (Estimated) is calculated from GhostNet, NASA Aqua MODIS Chl a and NOAA GOES Imager SST data. THIS IS AN EXPERIMENTAL PRODUCT: intended...

  10. SST, Aqua MODIS, NPP, 0.025 degrees, Pacific Ocean, Daytime

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA CoastWatch provides SST data from NASA's Aqua Spacecraft. Measurements are gathered by the Moderate Resolution Imaging Spectroradiometer (MODIS) carried aboard...

  11. SST, Aqua MODIS, NPP, 0.0125 degrees, Gulf of Mexico, Night time (4 microns)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA CoastWatch provides SST data from NASA's Aqua Spacecraft. Measurements are gathered by the Moderate Resolution Imaging Spectroradiometer (MODIS) carried aboard...

  12. SST, Aqua MODIS, NPP, 0.0125 degrees, East US, Day and Night

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA CoastWatch provides SST data from NASA's Aqua Spacecraft. Measurements are gathered by the Moderate Resolution Imaging Spectroradiometer (MODIS) carried aboard...

  13. Global NOAA CoastWatch Chlorophyll Frontal Product from MODIS/Aqua (NCEI Accession 0110333)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — MODIS/Aqua chlorophyll frontal products: the NOAA Okeanos operational production system produces near real-time chlorophyll frontal products (magnitude and...

  14. Spatial and Temporal Distribution of Clouds Observed by MODIS Onboard the Terra and Aqua Satellites

    Science.gov (United States)

    King, Michael D.; Platnick, Steven; Menzel, W. Paul; Ackerman, Steven A.; Hubanks, Paul A.

    2012-01-01

    The Moderate Resolution Imaging Spectroradiometer (MODIS) was developed by NASA and launched aboard the Terra spacecraft on December 18, 1999 and Aqua spacecraft on May 4, 2002. A comprehensive set of remote sensing algorithms for the retrieval of cloud physical and optical properties have enabled over twelve years of continuous observations of cloud properties from Terra and over nine years from Aqua. The archived products from these algorithms include 1 km pixel-level (Level-2) and global gridded Level-3 products. In addition to an extensive cloud mask, products include cloud-top properties (temperature, pressure, effective emissivity), cloud thermodynamic phase, cloud optical and microphysical parameters (optical thickness, effective particle radius, water path), as well as derived statistics. Results include the latitudinal distribution of cloud optical and radiative properties for both liquid water and ice clouds, as well as latitudinal distributions of cloud top pressure and cloud top temperature. MODIS finds the cloud fraction, as derived by the cloud mask, is nearly identical during the day and night, with only modest diurnal variation. Globally, the cloud fraction derived by the MODIS cloud mask is approx.67%, with somewhat more clouds over land during the afternoon and less clouds over ocean in the afternoon, with very little difference in global cloud cover between Terra and Aqua. Overall, cloud fraction over land is approx.55%, with a distinctive seasonal cycle, whereas the ocean cloudiness is much higher, around 72%, with much reduced seasonal variation. Cloud top pressure and temperature have distinct spatial and temporal patterns, and clearly reflect our understanding of the global cloud distribution. High clouds are especially prevalent over the northern hemisphere continents between 30 and 50 . Aqua and Terra have comparable zonal cloud top pressures, with Aqua having somewhat higher clouds (cloud top pressures lower by 100 hPa) over land due to

  15. Combining vegetation index and model inversion methods for theextraction of key vegetation biophysical parameters using Terra and Aqua MODIS reflectance data

    DEFF Research Database (Denmark)

    Houborg, Rasmus Møller; Søgaard, Henrik; Bøgh, Eva

    2007-01-01

    and computationally efficient VI approach makes the combined retrieval scheme for LAI, TCab, and VWC suitable for large-scale mapping operations. In order to facilitate application of the canopy reflectance model to heterogeneous forested areas, a simple correction scheme was elaborated, which was found to improve...... forest LAI predictions significantly and also provided more realistic values of leaf chlorophyll contents. The inversion scheme was designed to enable biophysical parameter retrievals for land cover classes characterized by contrasting canopy architectures, leaf inclination angles, and leaf biochemical...

  16. Terra and Aqua MODIS Thermal Emissive Bands On-Orbit Calibration and Performance

    Science.gov (United States)

    Xiong, Xiaoxiong; Wu, Aisheng; Wenny, Brian N.; Madhavan, Sriharsha; Wang, Zhipeng; Li, Yonghong; Chen, Na; Barnes, William L.; Salomonson, Vincent V.

    2015-01-01

    Since launch, the Moderate Resolution Imaging Spectroradiometer (MODIS) instruments on the Terra and Aqua spacecraft have operated successfully for more than 14 and 12 years, respectively. A key instrument for National Aeronautics and Space Administration Earth Observing System missions, MODIS was designed to make continuous observations for studies of Earth's land, ocean, and atmospheric properties and to extend existing data records from heritage Earth observing sensors. The 16 thermal emissive bands (TEBs) (3.75-14.24 micrometers) are calibrated on orbit using a temperature controlled blackbody (BB). Both Terra and Aqua MODIS BBs have displayed minimal drift over the mission lifetime, and the seasonal variations of the BB temperature are extremely small in Aqua MODIS. The long-term gain and noise equivalent difference in temperature performance of the 160 TEB detectors on both MODIS instruments have been well behaved and generally very stable. Small but noticeable variations of Aqua MODIS bands 33-36 (13.34-14.24 micrometer) response in recent years are primarily due to loss of temperature control margin of its passive cryoradiative cooler. As a result, fixed calibration coefficients, previously used by bands when the BB temperature is above their saturation temperatures, are replaced by the focal-plane-temperature-dependent calibration coefficients. This paper presents an overview of the MODIS TEB calibration, the on-orbit performance, and the challenging issues likely to impact the instruments as they continue operating well past their designed lifetime of six years.

  17. Intercomparison of column aerosol optical depths from CALIPSO and MODIS-Aqua

    OpenAIRE

    Kittaka, C.; Winker, D. M.; M. A. Vaughan; Omar, A.; Remer, L. A.

    2011-01-01

    The Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) is carried on the CALIPSO satellite and has acquired global aerosol profiles since June 2006. CALIPSO is flown in formation with the Aqua satellite as part of the A-train satellite constellation, so that a large number of coincident aerosol observations are available from CALIOP and the MODIS-Aqua instrument. This study compares column aerosol optical depth at 0.532 μm derived from CALIOP aerosol profiles with MO...

  18. Inter-satellite comparison and evaluation of Navy SNPP VIIRS and MODIS-Aqua ocean color properties

    Science.gov (United States)

    Ladner, S. D.; Arnone, R.; Vandermeulen, R.; Martinolich, P.; Lawson, A.; Bowers, J.; Crout, R.; Ondrusek, M.; Fargion, G.

    2014-05-01

    Navy operational ocean color products of inherent optical properties and radiances are evaluated for the Suomi-NPP VIIRS and MODIS-Aqua sensors. Statistical comparisons with shipboard measurements were determined in a wide variety of coastal, shelf and offshore locations in the Northern Gulf of Mexico during two cruises in 2013. Product consistency between MODIS-Aqua, nearing its end-of-life expectancy, and Suomi-NPP VIIRS is being evaluated for the Navy to retrieve accurate ocean color properties operationally from VIIRS in a variety of water types. Currently, the existence, accuracy and consistency of multiple ocean color sensors (VIIRS, MODIS-Aqua) provides multiple looks per day for monitoring the temporal and spatial variability of coastal waters. Consistent processing methods and algorithms are used in the Navy's Automated Processing System (APS) for both sensors for this evaluation. The inherent optical properties from both sensors are derived using a coupled ocean-atmosphere NIR correction extending well into the bays and estuaries where high sediment and CDOM absorption dominate the optical signature. Coastal optical properties are more complex and vary from chlorophyll-dominated waters offshore. The in-water optical properties were derived using vicariously calibrated remote sensing reflectances and the Quasi Analytical Algorithm (QAA) to derive the Inherent Optical Properties (IOP's). The Naval Research Laboratory (NRL) and the JPSS program have been actively engaged in calibration/validation activities for Visible Infrared Imager Radiometer Suite (VIIRS) ocean color products.

  19. Assessment of diverse algorithms applied on MODIS Aqua and Terra data over land surfaces in Europe

    OpenAIRE

    Glantz, P.; Tesche, M

    2012-01-01

    The aim of the present study is to validate AOT (aerosol optical thickness) and Ångström exponent (α), obtained with the SAER (Satellite AErosol Retrieval) algorithm for MODIS (MODerate resolution Imaging Spectroradiometer) Aqua and Terra calibrated level 1 data (1 km horizontal resolution at ground) and MODIS Collection 5 (c005) standard product retrievals (10 km), against AERONET (AErosol RObotic NETwork) observations over land surfaces in Europe. The three time periods investigated in ...

  20. U.S. West Coast MODIS Aqua High Resolution SST Climatology Fields (July 2002 - March 2014)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This suite of CHLA and SST climatology and anomaly data products are derived from daily, 0.0125 degree x 0.0125 degree, MODIS Aqua CHLA and SST fields that cover...

  1. U.S. West Coast MODIS Aqua High Resolution CHLA Anomaly Fields (July 2002 - March 2014)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This suite of CHLA and SST climatology and anomaly data products are derived from daily, 0.0125 degree x 0.0125 degree, MODIS Aqua CHLA and SST fields that cover...

  2. U.S. West Coast MODIS Aqua High Resolution CHLA Climatology Fields (July 2002 - March 2014)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This suite of CHLA and SST climatology and anomaly data products are derived from daily, 0.0125 degree x 0.0125 degree, MODIS Aqua CHLA and SST fields that cover...

  3. U.S. West Coast MODIS Aqua High Resolution SST Anomaly Fields (July 2002 - March 2014)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This suite of CHLA and SST climatology and anomaly data products are derived from daily, 0.0125 degree x 0.0125 degree, MODIS Aqua CHLA and SST fields that cover...

  4. Assessment of diverse algorithms applied on MODIS Aqua and Terra data over land surfaces in Europe

    Directory of Open Access Journals (Sweden)

    P. Glantz

    2012-03-01

    Full Text Available The aim of the present study is to validate AOT (aerosol optical thickness and Ångström exponent (α, obtained with the SAER (Satellite AErosol Retrieval algorithm for MODIS (MODerate resolution Imaging Spectroradiometer Aqua and Terra calibrated level 1 data (1 km horizontal resolution at ground and MODIS Collection 5 (c005 standard product retrievals (10 km, against AERONET (AErosol RObotic NETwork observations over land surfaces in Europe. The three time periods investigated in this study have been chosen to enable a validation of the algorithm for a maximal possible variation in sun elevations. For several of the cases analyzed here the Aqua and Terra satellites passed the investigation area twice during a day. Thus, beside a variation in the sun elevation the satellite retrievals have also on a daily basis been performed with a significant variation in the satellite-viewing geometry. An inter-comparison of the two algorithms has also been performed. The validation with AERONET shows that the MODIS c005 retrieved AOT is, for the wavelengths 0.469 and 0.500 nm, on the whole within the expected uncertainty for one standard deviation of the MODIS c005 retrievals over Europe (Δ AOT = ±0.05±0.15 AOT. The SAER estimated AOT for the wavelength 0.443 nm also agree reasonable well with AERONET. Thus, the majority of the SAER AOT values are within the MODIS expected uncertainty range, although somewhat larger root mean square deviation occurs compared to the results obtained with the MODIS c005 algorithm. The discrepancy between SAER and AERONET AOT is, however, substantially larger for the wavelength 488 nm, which means that the values are to a large extent outside of the expected MODIS uncertainty range. Both satellite retrieval algorithms are unable to estimate α accurately, although the MODIS c005 algorithm performs better. Based on the inter-comparison of the SAER and MODIS c005 algorithms it was found that the SAER is able to obtain

  5. Fluorescence, Aqua MODIS, NPP, 0.125 degrees, West US

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — MODIS measures chlorophyll fluorescence, which gives insight into the physiology of phytoplankton in the ocean. When phytoplankton are under stress, the rate at...

  6. Fluorescence, Aqua MODIS, NPP, 0.125 degrees, East US

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — MODIS measures chlorophyll fluorescence, which gives insight into the physiology of phytoplankton in the ocean. When phytoplankton are under stress, the rate at...

  7. Electronic Crosstalk in Aqua MODIS Long-Wave Infrared Photovoltaic Bands

    Directory of Open Access Journals (Sweden)

    Junqiang Sun

    2016-09-01

    Full Text Available Recent investigations have discovered that Terra MODerate-resolution Imaging Spectroradiometer (MODIS long-wave infrared (LWIR photovoltaic (PV bands, bands 27–30, have strong crosstalk among themselves. The linear model developed to test the electronic crosstalk effect was instrumental in the first discovery of the effect in Terra MODIS band 27, and through subsequent investigations the model and the correction algorithm were tested further and established to be correct. It was shown that the correction algorithm successfully mitigated the anomalous features in the calibration coefficients as well as the severe striping and the long-term drift in the Earth view (EV retrievals for the affected Terra bands. Here, the examination into Aqua MODIS using the established methodology confirms the existence of significant crosstalk contamination in its four LWIR PV, although the finding shows the overall effect to be of lesser degree. The crosstalk effect is characterized and the crosstalk correction coefficients are derived for all four Aqua LWIR PV bands via analysis of signal contamination in the lunar imagery. Sudden changes in the crosstalk contamination are clearly seen, as also in the Terra counterparts in previous investigations. These sudden changes are consistent with the sudden jumps observed in the linear calibration coefficients for many years, thus this latest finding provides an explanation to the long-standing but unexplained anomalies in the calibration coefficients of the four Aqua LWIR bands. It is also shown that the crosstalk contamination for these bands are of similar level for the two MODIS instruments in the early mission that can lead to as much as 2 K increase in brightness temperature for the affected bands, thus demonstrating significant impact on the science results already started at the early going. As Aqua MODIS is a legacy sensor, the crosstalk correction to its LWIR PV bands will be important to remove the impact of

  8. Validation of MODIS Terra and Aqua Ice Surface Temperatures at Summit, Greenland

    Science.gov (United States)

    Hall, D. K.; Shuman, C. A.; Xiong, X.; Wenny, B. N.; DiGirolamo, N. E.

    2014-12-01

    Ice-surface temperature (IST) is used in many studies, for example for validation of model output and for detection of leads and thin ice in sea ice. The MODerate-resolution Imaging Spectroradiometer (MODIS) instruments on the Terra and Aqua satellites are useful for mapping IST of sea ice and the Greenland ice sheet (Hall et al., 2012), and validation of the ISTs derived from MODIS has been an ongoing effort (e.g., Koenig & Hall, 2010; Shuman et al., 2014). Recent results call into question the calibration of the MODIS-derived ISTs at very cold temperatures that are characteristic of the Greenland ice sheet high interior during winter (Shuman et al., 2014). In the present work, we investigate the calibration of MODIS IR bands 31 (10.780 - 11.280 µm) and 32 (11.770 - 12.270 µm) under very cold conditions. MODIS IR bands are calibrated using a quadratic algorithm. In Collection 6 (C6), the offset and nonlinear calibration coefficients are computed from data collected during the blackbody cool-down vs the warm-up data used in Collection 5 (C5). To improve the calibration accuracy for low-temperature scenes, the offset terms are set to 0. In general, Aqua MODIS bands 31 and 32 perform better than Terra MODIS bands 31 and 32. One of the reasons is that the Aqua bands have a lower saturation temperature (~340 K) than the Terra (~380 K) bands, and lower saturation or smaller dynamic range means better resolution. As compared to ~2-m NOAA air temperatures (TA) at Summit, Greenland, Shuman et al. (2014) show a small (~0.5°C) offset in Terra MODIS-derived IST vs TA near 0°C, and an increasingly larger offset (up to ~5°C) as TA drops to -60°C. To investigate this further, we compare Terra and Aqua C5 and C6 ISTs with TA data from Summit. This work will document the calibration of bands 31 and 32 at very low temperatures in C5 and C6. Hall, D.K., et al., 2012: Satellite-Derived Climate-Quality Data Record of the Clear-Sky Surface Temperature of the Greenland Ice Sheet

  9. Estimation of Daily Sunshine Duration from Terra and Aqua MODIS Data

    OpenAIRE

    Kandirmaz, H. M.; K. Kaba

    2014-01-01

    Some studies have shown that the estimation of global sunshine duration can be done with the help of geostationary satellites because they can record several images of the same location in a day. In this paper, images obtained from the MODIS (Moderate Resolution Imaging Spectroradiometer) sensors of polar orbiting satellites Aqua and Terra were used to estimate daily global sunshine duration for any region in Turkey. A new quadratic correlation between daily mean cloud cover index and relati...

  10. Optimized Merger of Ocean Chlorophyll Algorithms of MODIS-Aqua and VIIRS

    OpenAIRE

    Kahru, M.; Kudela, RM; Anderson, CR; Mitchell, BG

    2015-01-01

    Standard ocean chlorophyll-a (Chla) products from currently operational satellite sensors Moderate Resolution Imaging Spectroradiometer (MODIS) Aqua and Visible Infrared Imager Radiometer Suite (VIIRS) underestimate medium and high in situ Chla concentrations and have approximately 9% bias between each other in the California Current. By using the regional optimization approach of Kahru et al., we minimized the differences between satellite estimates and in situ match-ups as well as between e...

  11. Inter-comparison of Terra and Aqua MODIS Feflective Solar Bands using Suomi NPP VIIRS

    OpenAIRE

    Blonski, Slawomir; Cao, Changyong; Uprety, Sirish; Shao, Xi

    2013-01-01

    VIIRS (Visible Infrared Imager Radiometer Suite) onboard the Suomi NPP (National Polar-orbiting Partnership) satellite has been acquiring Earth observations for more than a year. During that time, SNO (Simultaneous Nadir Overpass) events have provided many opportunities for inter-comparisons between VIIRS and the MODIS (Moderate Resolution Imaging Spectroradiometer) instruments from the Aqua and Terra satellites. The SNOs have occurred over snow-covered Antarctica, which provided bright surfa...

  12. Use of LST images from MODIS/AQUA sensor as an indication of frost occurrence in RS

    Directory of Open Access Journals (Sweden)

    Débora de S. Simões

    2015-10-01

    Full Text Available ABSTRACTAlthough frost occurrence causes severe losses in agriculture, especially in the south of Brazil, the data of minimum air temperature (Tmin currently available for monitoring and predicting frosts show insufficient spatial distribution. This study aimed to evaluate the MDY11A1 (LST – Land Surface Temperature product, from the MODIS sensor on board the AQUA satellite as an estimator of frost occurrence in the southeast of the state of Rio Grande do Sul, Brazil. LST images from the nighttime overpass of the MODIS/AQUA sensor for the months of June, July and August from 2006 to 2012, and data from three conventional weather stations of the National Institute of Meteorology (INMET were used. Consistency was observed between Tmin data measured in weather stations and LST data obtained from the MODIS sensor. According to the results, LSTs below 3 ºC recorded by the MODIS/AQUA sensor are an indication of a favorable scenario to frost occurrence.

  13. Evaluation of monthwise and overall trends of AOD over Indian cities using MODIS Aqua and Terra retrievals

    Science.gov (United States)

    Banerjee, Subhasis; Ghosh, Sanjay

    2016-07-01

    Atmospheric aerosols have been shown to have profound impact on climate system and human health. Regular and systematic monitoring of ambient air is thus necessary in order to asses its impact. There are several ground based stations worldwide employed in this service but still their numbers are inadequate and it is even almost impossible to have such stations at difficult geographical terrains and take measurement throughout the year. Aerosol optical depth or AOD, which is a measure of extinction of incoming solar radiation, serves as proxy to atmospheric aerosol loading. Various sensors onboard different satellites take routine measurement of AOD throughout the year. Satellite based AOD is used in many studies due to their wide coverage and availability for a longer time period. Satellite measures reflected solar radiation at the top of the atmosphere. Column integrated value of aerosol are routinely estimated from those measurements using suitable inversion algorithms. MODIS instrument onboard Aqua and Terra satellites of Earth Observing System takes routine measurement in wide spectral range. We used those data to evaluate trend of AOD over almost fifty Indian cities having population more than a million. The cities we have chosen spread over almost entire length and breadth of the country. Few such studies have already been conducted using MODIS data. They typically used level 3 data. Since Level 3 data comes in 1x 1 degree gridded form they provide average value over a vast geographical region. We used level 2 dataset to enable us taking smaller region(1/2 x 1/2 degree here) centering the region of our interest . We used seasonal Mann-Kendall (M-K) statistics coupled with Sen's non-parametric slope estimation procedure to estimate monthwise and overall(i.e., yearly trend taking seasonality into account) AOD trend. We used median AOD for each month of every year to discard very high AOD's which we often get due to cloud contamination. Seasonal M-K test takes

  14. Optimized extraction of daily bio-optical time series derived from MODIS/Aqua imagery for Lake Tanganyika, Africa

    DEFF Research Database (Denmark)

    Horion, Stéphanie; Bergamino, N; Stenuite, S;

    2010-01-01

    Lake Tanganyika is one of the world's great freshwater ecosystems. In recent decades its hydrodynamic characteristics have undergone important changes that have had consequences on the lake's primary productivity. The establishment of a long-term Ocean Color dataset for Lake Tanganyika...... the MODIS-Aqua sensor. Standard MODIS Aqua Ocean Color products were found to not provide a suitable calibration for high altitude lakes such as the Lake Tanganyika. An optimization of the extraction process and the validation of the dataset were performed with independent sets of in situ measurements. Our...

  15. Fractional Snowcover Estimates from Earth Observing System (EOS) Terra and Aqua Moderate Resolution Imaging Spectroradiometer (MODIS)

    Science.gov (United States)

    Salomonson, Vincent V.

    2002-01-01

    The Moderate Resolution Imaging Spectroradiometer (MODIS) on the NASA Earth Observing System (EOS) Terra and Aqua missions has shown considerable capability for mapping snowcover. The typical approach that has used, along with other criteria, the Normalized Snow Difference Index (NDSI) that takes the difference between 500 meter observations at 1.64 micrometers (MODIS band 6) and 0.555 micrometers (MODIS band 4) over the sum of these observations to determine whether MODIS pixels are snowcovered or not in mapping the extent of snowcover. For many hydrological and climate studies using remote sensing of snowcover, it is desirable to assess if the MODIS snowcover observations could not be enhanced by providing the fraction of snowcover in each MODIS observation (pixel). Pursuant to this objective studies have been conducted to assess whether there is sufficient "signal%o in the NDSI parameter to provide useful estimates of fractional snowcover in each MODIS 500 meter pixel. To accomplish this objective high spatial resolution (30 meter) Landsat snowcover observations were used and co-registered with MODIS 500 meter pixels. The NDSI approach was used to assess whether a Landsat pixel was or was not snowcovered. Then the number of snowcovered Landsat pixels within a MODIS pixel was used to determine the fraction of snowcover within each MODIS pixel. The e results were then used to develop statistical relationships between the NDSI value for each 500 meter MODIS pixel and the fraction of snowcover in the MODIS pixel. Such studies were conducted for three widely different areas covered by Landsat scenes in Alaska, Russia, and the Quebec Province in Canada. The statistical relationships indicate that a 10 percent accuracy can be attained. The variability in the statistical relationship for the three areas was found to be remarkably similar (-0.02 for mean error and less than 0.01 for mean absolute error and standard deviation). Independent tests of the relationships were

  16. Surface circulation patterns in the Gulf of California derived from MODIS Aqua 250 m

    Science.gov (United States)

    Martínez-Flores, G.; Salinas-González, F.; Gutiérrez de Velasco-Sanromán, G.; Godínez-Orta, L.

    2009-04-01

    The Gulf of California (GC) is a marginal elongated and semi-enclosed sea located at northwest of Mexico, between the Peninsula of Baja California and the mainland Mexico. The considered area average 150 km in width and 1500 km in length, from the mouth of the Colorado River to Cabo Corrientes, Jalisco. It has a maximum depth of 3600 m at the southern inlet and the northern region average 200 m in deep. The study of superficial circulation patterns in the GC is of interest because its relevance to the mechanisms of transport for distribution of a variety of materials -plankton, contaminants, microalgae, etc.- and its association with areas of sedimentary deposits, zones where there is a higher probability for fishing or related to the presence of certain species of marine life. Recent studies explain the circulation of the GC as a result of the Pacific Ocean's forcing, wind, heat fluxes on the sea surface and the interaction between the flow produced by these agents and bathymetry. The objective of this work was to obtain evidence of the patterns of surface circulation using a spatial resolution of 250 m over a period of two to seven days (depending on cloud cover), which offered images from the MODIS Level 1B. This essay is an attempt to contribute with more information to the understanding of the regional dynamics of the GC and its local influence on the zones bordering the coast. Thus, MODIS Aqua 250 m data was used, to which algorithms were applied in order to enhance the contrast of reflectance levels of these bands (0.620-0.670 and 0.841-0.876 µm) within the marine environment. The results are associated with suspended particulate matter (SPM), which we used as tracers of the surface circulation, using a sequence of images from January 2004 to December 2008. Algorithms for dust and cloud detection were used and incorporated with thermal band images, in which zones of terrigenous contribution by eolian transport were identified. Furthermore, pluvial

  17. Assessment of two aerosol optical thickness retrieval algorithms applied to MODIS Aqua and Terra measurements in Europe

    OpenAIRE

    Glantz, P.; Tesche, M

    2012-01-01

    The aim of the present study is to validate AOT (aerosol optical thickness) and Ångström exponent (α), obtained from MODIS (MODerate resolution Imaging Spectroradiometer) Aqua and Terra calibrated level 1 data (1 km horizontal resolution at ground) with the SAER (Satellite AErosol Retrieval) algorithm and with MODIS Collection 5 (c005) standard product retrievals (10 km horizontal resolution), against AERONET (AErosol RObotic NETwork) sun photometer observations over land su...

  18. Response versus scan-angle corrections for MODIS reflective solar bands using deep convective clouds

    Science.gov (United States)

    Bhatt, Rajendra; Angal, Amit; Doelling, David R.; Xiong, Xiaoxiong; Wu, Aisheng; Haney, Conor O.; Scarino, Benjamin R.; Gopalan, Arun

    2016-05-01

    The absolute radiometric calibration of the reflective solar bands (RSBs) of Aqua- and Terra-MODIS is performed using on-board calibrators. A solar diffuser (SD) panel along with a solar diffuser stability monitor (SDSM) system, which tracks the degradation of the SD over time, provides the baseline for calibrating the MODIS sensors. MODIS also views the moon and deep space through its space view (SV) port for lunar-based calibration and computing the background, respectively. The MODIS instrument views the Earth's surface using a two-sided scan mirror, whose reflectance is a function of the angle of incidence (AOI) and is described by response versus scan-angle (RVS). The RVS for both MODIS instruments was characterized prior to launch. MODIS also views the SD and the moon at two different AOIs. There is sufficient evidence that the RVS is changing on orbit over time and as a function of wavelength. The SD and lunar observation scans can only track the RVS variation at two AOIs. Consequently, the MODIS Characterization Support Team (MCST) developed enhanced approaches that supplement the onboard calibrator measurements with responses from the pseudo-invariant desert sites. This approach has been implemented in Level 1B (L1B) Collection 6 (C6) for select short-wavelength bands. This paper presents an alternative approach of characterizing the mirror RVS to derive the time-dependent RVS correction factors for MODIS RSBs using tropical deep convective cloud (DCC) targets. An initial assessment of the DCC response from Aqua-MODIS band 1 C6 data indicates evidence of RVS artifacts, which are not uniform across the scans and are more prevalent at the beginning of the earth-view scan.

  19. Variability of particulate organic carbon in inland waters observed from MODIS Aqua imagery

    International Nuclear Information System (INIS)

    Surface concentrations of particulate organic carbon (POC) in shallow inland lakes were estimated using MODIS Aqua data. A power regression model of the direct empirical relationship between POC and the atmospherically Rayleigh-corrected MODIS product (Rrc,645-Rrc,1240)/(Rrc,859-Rrc,1240) was developed (R2 = 0.72, RMSE = 35.86 μgL−1, p < 0.0001, N = 47) and validated (RMSE = 44.46 μgL−1, N = 16) with field data from 56 lakes in the Middle and Lower reaches of the Yangtze River, China. This algorithm was applied to an 11 year series of MODIS data to determine the spatial and temporal distribution of POC in a wide range of lakes with different trophic and optical properties. The results indicate that there is a general increase in minimum POC concentrations in lakes from middle to lower reaches of the Yangtze River. The temporal dynamics of springtime POC in smaller lakes were found to be influenced by local meteorological conditions, in particular precipitation and wind speed, while larger lakes were found to be more sensitive to air temperature. (letter)

  20. Validation of JAXA/MODIS Sea Surface Temperature in Water around Taiwan Using the Terra and Aqua Satellites

    Directory of Open Access Journals (Sweden)

    Ming-An Lee

    2010-01-01

    Full Text Available The research vessel-based Conductivity Temperature Depth profiler (CTD provides underwater measurements of the bulk sea surface temperature (SST at the depths of shallower than 5 m. The CTD observations of the seas around Taiwan provide useful data for comparison with SST of MODIS (Moderate Resolution Imaging Spectroradiometers aboard Aqua and Terra satellites archived by JAXA (Japan Aerospace Exploration Agency. We produce a high-resolution (1 km MODIS SST by using Multi-Channel SST (MCSST algorithm. There were 1516 cloud-free match-up data pairs of MODIS SST and in situ measurements during the period from 2003 - 2005. The difference of the root mean square error (RMSE of satellite observations from each platform during the day and at night was: _ in Aqua daytime, _ in Aqua nighttime, _ in Terra daytime, and _ in Terra nighttime. The total analysis of MODIS-derived SST shows good agreement with a bias of _ and RMSE of _ The analyses indicate that the bias of Aqua daytime was always positive throughout the year and the large RMSE should be attributed to the large positive bias _ under diurnal warming. It was also found that the bias of Terra daytime was usually negative with a mean bias of _ its large RMSE should be treated with care because of low solar radiation in the morning.

  1. MODIS/Aqua Clear Sky Radiance Statistics Daily L3 Global 25km Equal Area V006

    Data.gov (United States)

    National Aeronautics and Space Administration — MODIS daily averaged clear-sky radiance (thermal bands) and reflectance (visible bands) statistics in selected MODIS bands are stored on a global grid map....

  2. Effect of MODIS Terra Radiometric Calibration Improvements on Collection 6 Deep Blue Aerosol Products: Validation and Terra/Aqua Consistency

    Science.gov (United States)

    Sayer, A. M.; Hsu, N. C.; Bettenhausen, C.; Jeong, M.-J.; Meister, G.

    2015-01-01

    The Deep Blue (DB) algorithm's primary data product is midvisible aerosol optical depth (AOD). DB applied to Moderate Resolution Imaging Spectroradiometer (MODIS) measurements provides a data record since early 2000 for MODIS Terra and mid-2002 for MODIS Aqua. In the previous data version (Collection 5, C5), DB production from Terra was halted in 2007 due to sensor degradation; the new Collection 6 (C6) has both improved science algorithms and sensor radiometric calibration. This includes additional calibration corrections developed by the Ocean Biology Processing Group to address MODIS Terra's gain, polarization sensitivity, and detector response versus scan angle, meaning DB can now be applied to the whole Terra record. Through validation with Aerosol Robotic Network (AERONET) data, it is shown that the C6 DB Terra AOD quality is stable throughout the mission to date. Compared to the C5 calibration, in recent years the RMS error compared to AERONET is smaller by approximately 0.04 over bright (e.g., desert) and approximately 0.01-0.02 over darker (e.g., vegetated) land surfaces, and the fraction of points in agreement with AERONET within expected retrieval uncertainty higher by approximately 10% and approximately 5%, respectively. Comparisons to the Aqua C6 time series reveal a high level of correspondence between the two MODIS DB data records, with a small positive (Terra-Aqua) average AOD offset Terra DB AOD data remain stable (to better than 0.01 AOD) throughout the mission to date, suitable for quantitative scientific analyses.

  3. The NASA Earth Observing System (EOS) Terra and Aqua Mission Moderate Resolution Imaging Spectroradiometer (MODIS: Science and Applications

    Science.gov (United States)

    Salomnson, Vincent V.

    2003-01-01

    The Moderate Resolution Imaging Spectroradiometer (MODIS) on the Earth Observing System (EOS) Terra Mission began to produce data in February 2000. The EOS Aqua mission was launched successfully May 4,2002 with another MODIS on it and "first light" observations occurred on June 24,2002. The Terra MODIS is in a sun-synchronous orbit going north to south in the daylight portion of the orbit crossing the equator at about 1030 hours local time. The Aqua spacecraft operates in a sun-synchronous orbit going south to north in the daylight portion of the orbit crossing the equator at approximately 1330 hours local time. The spacecraft, instrument, and data systems for both MODIS instruments are performing well and are producing a wide variety of data products useful for scientific and applications studies in relatively consistent fashion extending from November 2000 to the present. Within the approximately 40 MODIS data products, several are new and represent powerful and exciting capabilities such the ability to provide observations over the globe of fire occurrences, microphysical properties of clouds and sun-stimulated fluorescence from phytoplankton in the surface waters of the ocean. The remainder of the MODIS products exceeds or, at a minimum, matches the capabilities of products from heritage sensors such as, for example, the Advanced Very High Resolution Radiometer (AVHRR). Efforts are underway to provide data sets for the greater Earth science community and to improve access to these products at the various Distributed Active Archive Centers (DAAC's) or through Direct Broadcast (DB) stations.

  4. GHRSST Level 2P Global Skin Sea Surface Temperature from the Moderate Resolution Imaging Spectroradiometer (MODIS) on the NASA Aqua satellite (GDS version 1)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Moderate-resolution Imaging Spectroradiometer (MODIS) is a scientific instrument (radiometer) launched by NASA in 2002 on board the Aqua satellite platform (a...

  5. MODIS/Aqua MYD11A2 Land Surface Temperature & Emissivity 8-Day L3 Global 1km Gird SIN Version 6

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The MODIS/Aqua Land Surface Temperature and Emissivity (LST/E) products provide per-pixel temperature and emissivity values in a sequence of swath-based global...

  6. MODIS/Aqua MYD11_L2 Land Surface Temperature and Emissivity 5-Minute L2 Swath 1 km Version 6

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The MODIS/Aqua Land Surface Temperature and Emissivity (LST/E) products provide per-pixel temperature and emissivity values in a sequence of swath-based global...

  7. MODIS/Aqua MYD11C3 Land Surface Temperature/Emissivity Monthly L3 Global 0.05Deg CMG Version 6

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The MODIS/Aqua Land Surface Temperature and Emissivity (LST/E) products provide per-pixel temperature and emissivity values in a sequence of swath-based global...

  8. MODIS/Aqua MYD11A1 Land Surface Temperature and Emissivity Daily L3 Global 1 km Grid SIN Version 6

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The MODIS/Aqua Land Surface Temperature and Emissivity (LST/E) products provide per-pixel temperature and emissivity values in a sequence of swath-based global...

  9. MODIS/Aqua MYD11C2 Land Surface Temperature/Emissivity 8-Day L3 Global 0.05Deg CMG Version 6

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The MODIS/Aqua Land Surface Temperature and Emissivity (LST/E) products provide per-pixel temperature and emissivity values in a sequence of swath-based global...

  10. MODIS/Aqua MYD11B1 Land Surface Temperature and Emissivity Daily L3 Global 5 km Grid SIN Version 6

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The MODIS/Aqua Land Surface Temperature and Emissivity (LST/E) products provide per-pixel temperature and emissivity values in a sequence of swath-based global...

  11. MODIS/Aqua MYD11C1 Land Surface Temperature and Emissivity Daily L3 Global 0.05Deg CMG Version 6

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The MODIS/Aqua Land Surface Temperature and Emissivity (LST/E) products provide per-pixel temperature and emissivity values in a sequence of swath-based global...

  12. Effect of MODIS Terra radiometric calibration improvements on Collection 6 Deep Blue aerosol products: Validation and Terra/Aqua consistency

    Science.gov (United States)

    Sayer, A. M.; Hsu, N. C.; Bettenhausen, C.; Jeong, M.-J.; Meister, G.

    2015-12-01

    The Deep Blue (DB) algorithm's primary data product is midvisible aerosol optical depth (AOD). DB applied to Moderate Resolution Imaging Spectroradiometer (MODIS) measurements provides a data record since early 2000 for MODIS Terra and mid-2002 for MODIS Aqua. In the previous data version (Collection 5, C5), DB production from Terra was halted in 2007 due to sensor degradation; the new Collection 6 (C6) has both improved science algorithms and sensor radiometric calibration. This includes additional calibration corrections developed by the Ocean Biology Processing Group to address MODIS Terra's gain, polarization sensitivity, and detector response versus scan angle, meaning DB can now be applied to the whole Terra record. Through validation with Aerosol Robotic Network (AERONET) data, it is shown that the C6 DB Terra AOD quality is stable throughout the mission to date. Compared to the C5 calibration, in recent years the RMS error compared to AERONET is smaller by ˜0.04 over bright (e.g., desert) and ˜0.01-0.02 over darker (e.g., vegetated) land surfaces, and the fraction of points in agreement with AERONET within expected retrieval uncertainty higher by ˜10% and ˜5%, respectively. Comparisons to the Aqua C6 time series reveal a high level of correspondence between the two MODIS DB data records, with a small positive (Terra-Aqua) average AOD offset radiometric calibration efforts and that the C6 MODIS Terra DB AOD data remain stable (to better than 0.01 AOD) throughout the mission to date, suitable for quantitative scientific analyses.

  13. Assessment of two aerosol optical thickness retrieval algorithms applied to MODIS Aqua and Terra measurements in Europe

    Directory of Open Access Journals (Sweden)

    P. Glantz

    2012-07-01

    Full Text Available The aim of the present study is to validate AOT (aerosol optical thickness and Ångström exponent (α, obtained from MODIS (MODerate resolution Imaging Spectroradiometer Aqua and Terra calibrated level 1 data (1 km horizontal resolution at ground with the SAER (Satellite AErosol Retrieval algorithm and with MODIS Collection 5 (c005 standard product retrievals (10 km horizontal resolution, against AERONET (AErosol RObotic NETwork sun photometer observations over land surfaces in Europe. An inter-comparison of AOT at 0.469 nm obtained with the two algorithms has also been performed. The time periods investigated were chosen to enable a validation of the findings of the two algorithms for a maximal possible variation in sun elevation. The satellite retrievals were also performed with a significant variation in the satellite-viewing geometry, since Aqua and Terra passed the investigation area twice a day for several of the cases analyzed. The validation with AERONET shows that the AOT at 0.469 and 0.555 nm obtained with MODIS c005 is within the expected uncertainty of one standard deviation of the MODIS c005 retrievals (ΔAOT = ± 0.05 ± 0.15 · AOT. The AOT at 0.443 nm retrieved with SAER, but with a much finer spatial resolution, also agreed reasonably well with AERONET measurements. The majority of the SAER AOT values are within the MODIS c005 expected uncertainty range, although somewhat larger average absolute deviation occurs compared to the results obtained with the MODIS c005 algorithm. The discrepancy between AOT from SAER and AERONET is, however, substantially larger for the wavelength 488 nm. This means that the values are, to a larger extent, outside of the expected MODIS uncertainty range. In addition, both satellite retrieval algorithms are unable to estimate α accurately, although the MODIS c005 algorithm performs better. Based on the inter-comparison of the SAER and MODIS c005 algorithms, it was found that SAER on the whole is

  14. Comparison of chlorophyll in the Red Sea derived from MODIS-Aqua and in vivo fluorescence

    KAUST Repository

    Brewin, Robert J W

    2013-09-01

    The Red Sea is a unique marine environment but relatively unexplored. The only available long-term biological dataset at large spatial and temporal scales is remotely-sensed chlorophyll observations (an index of phytoplankton biomass) derived using satellite measurements of ocean colour. Yet such observations have rarely been compared with in situ data in the Red Sea. In this paper, satellite chlorophyll estimates in the Red Sea from the MODIS instrument onboard the Aqua satellite are compared with three recent cruises of in vivo fluorometric chlorophyll measurements taken in October 2008, March 2010 and September to October 2011. The performance of the standard NASA chlorophyll algorithm, and that of a new band-difference algorithm, is found to be comparable with other oligotrophic regions in the global ocean, supporting the use of satellite ocean colour in the Red Sea. However, given the unique environmental conditions of the study area, regional algorithms are likely to fare better and this is demonstrated through a simple adjustment to the band-difference algorithm. © 2013 Elsevier Inc.

  15. One of the Possible Causes for Diatom Appearance in Ariake Bay Area in Japan In the Winter from 2010 to 2015 (Clarified with AQUA/MODIS

    Directory of Open Access Journals (Sweden)

    Kohei Arai

    2016-10-01

    Full Text Available One of the possible causes for diatom appearance in Ariake bay area I Japan in the winter seasons from 2010 to 2015 is clarified with AQUA/MODIS of remote sensing satellite. Two months (January and February AQUA/MODIS derived chlorophyll-a concentration are used for analysis of diatom appearance. Match-up data of AQUA/MODIS with the evidence of the diatom appearance is extracted from the MODIS database. Through experiments, it is found that diatom appears after a long period time of relatively small size of red tide appearance. Also, it depends on the weather conditions and tidal effect as well as water current in the bay area in particular.

  16. The Characterization of Deep Convective Cloud Albedo as a Calibration Target Using MODIS Reflectances

    Science.gov (United States)

    Doelling, David R.; Hong, Gang; Morstad, Daniel; Bhatt, Rajendra; Gopalan, Arun; Xiong, Jack

    2010-01-01

    There are over 25 years of historical satellite data available to climate analysis. The historical satellite data needs to be well calibrated, especially in the visible, where there is no onboard calibration on operational satellites. The key to the vicarious calibration of historical satellites relies on invariant targets, such as the moon, Dome C, and deserts. Deep convective clouds (DCC) also show promise of being a stable invariant or predictable target viewable by all satellites, since they behave as solar diffusers. However DCC have not been well characterized for calibration. Ten years of well-calibrated MODIS is now available. DCC can easily be identified using IR thresholds, where the IR calibration can be traced to the onboard black-bodies. The natural variability of DCC albedo will be analyzed geographically and seasonally, especially difference of convection initiated over land or ocean. Functionality between particle size and ozone absorption with DCC albedo will be examined. Although DCC clouds are nearly Lambertion, the angular distribution of reflectances will be sampled and compared with theoretical models. Both Aqua and Terra MODIS DCC angular models will be compared for consistency. Normalizing angular geostationary DCC reflectances, which were calibrated against MODIS, with SCIAMACHY spectral reflectances and comparing them to MODIS DCC reflectances will inspect the usage of DCC albedos as an absolute calibration target.

  17. Modeling and Mapping Oyster Norovirus Outbreak Risks in Gulf of Mexico Using NASA MODIS Aqua Data

    Science.gov (United States)

    Deng, Z.; Wang, J.

    2015-12-01

    Norovirus is a highly infectious virus and the leading cause of foodborne disease outbreaks such as oyster norovirus outbreaks. Currently, there is no vaccine to prevent norovirus infection and no drug to treat it. This paper presents an integrated modeling and mapping framework for predicting the risk of norovirus outbreaks in oyster harvesting waters in the Northern Gulf of Mexico coast. The framework involves (1) the construction of three novel remote sensing algorithms for the retrieval of sea surface salinity, sea surface temperature, and gage height (tide level) using NASA MODIS Aqua data; (2) the development of probability-based Artificial Neural Network (ANN) model for the prediction of oyster norovirus outbreak risk, and (3) the application of the Local Indicators of Spatial Association (LISA) for mapping norovirus outbreak risks in oyster harvesting areas in the Northern Gulf of Mexico using the remotely sensed NASA data, retrieved data from the three remote sensing algorithms, and the ANN model predictions. The three remote sensing algorithms are able to correctly retrieve 94.1% of sea surface salinity, 94.0% of sea surface temperature, and 77.8% of gage height observed along the US coast, including the Pacific coast, the Gulf of Mexico coast, and the Atlantic coast. The gage height, temperature, and salinity are the three most important explanatory variables of the ANN model in terms of spatially distributed input variables. The ANN model is capable of hindcasting/predicting all oyster norovirus outbreaks occurred in oyster growing areas along the Gulf of Mexico coast where environmental data are available. The integrated modeling and mapping framework makes it possible to map daily risks of norovirus outbreaks in all oyster harvesting waters and particularly the oyster growing areas where no in-situ environmental data are available, greatly improving the safety of seafood and reducing outbreaks of foodborne disease.

  18. MODIS-Aqua detects Noctiluca scintillans and hotspots in the central Arabian Sea.

    Science.gov (United States)

    Dwivedi, R; Priyaja, P; Rafeeq, M; Sudhakar, M

    2016-01-01

    Northern Arabian Sea is considered as an ecologically sensitive area as it experiences a massive upwelling and long-lasting algal bloom, Noctiluca scintillans (green tide) during summer and spring-winter, respectively. Diatom bloom is also found to be co-located with N. scintillans and both have an impact on ecology of the basin. In-house technique of detecting species of these blooms from Moderate Resolution Imaging Spectroradiometer (MODIS)-Aqua data was used to generate a time-series of images revealing their spatial distribution. A study of spatial-temporal variability of these blooms using satellite data expressed a cyclic pattern of their spread over a period of 13 years. An average distribution of the blooms for January-March period revealed a peak in 2015 and minimum in 2013. Subsequently, a time-series of phytoplankton species images were generated for these 2 years to study their inter-annual variability and the associated factors. Species images during active phase of the bloom (February) in 2015 indicated development of N. scintillans and diatom in the central Arabian Sea also, up to 12° N. This observation was substantiated with relevant oceanic parameters measured from the ship as well as satellite data and the same is highlight of the paper. While oxygen depletion and release of ammonia associated with N. scintillans are detrimental for waters on the western side; it is relatively less extreme and supports the entire food chain on the eastern side. In view of these contrasting eco-sensitive events, it is a matter of concern to identify biologically active persistent areas, hot spots, in order to study their ecology in detail. An ecological index, persistence of the bloom, was derived from the time-series of species images and it is another highlight of our study. PMID:26690080

  19. MODIS/AQUA MYD14A1 Thermal Anomalies & Fire Daily L3 Global 1km

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — MODIS Thermal Anomalies/Fire products are primarily derived from MODIS 4- and 11-micrometer radiances. The fire detection strategy is based on absolute detection of...

  20. MODIS/AQUA MYD14 Thermal Anomalies & Fire 5-Min L2 Swath 1km

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — MODIS Thermal Anomalies/Fire products are primarily derived from MODIS 4- and 11-micrometer radiances. The fire detection strategy is based on absolute detection of...

  1. Inter-Comparison of S-NPP VIIRS and Aqua MODIS Thermal Emissive Bands Using Hyperspectral Infrared Sounder Measurements as a Transfer Reference

    OpenAIRE

    Yonghong Li; Aisheng Wu; Xiaoxiong Xiong

    2016-01-01

    This paper compares the calibration consistency of the spectrally-matched thermal emissive bands (TEB) between the Suomi National Polar-orbiting Partnership (S-NPP) Visible Infrared Imaging Radiometer Suite (VIIRS) and the Aqua Moderate Resolution Imaging Spectroradiometer (MODIS), using observations from their simultaneous nadir overpasses (SNO). Nearly-simultaneous hyperspectral measurements from the Aqua Atmospheric Infrared Sounder(AIRS) and the S-NPP Cross-track Infrared Sounder (CrIS) a...

  2. The comparison of MODIS-Aqua (C5 and CALIOP (V2 & V3 aerosol optical depth

    Directory of Open Access Journals (Sweden)

    J. Redemann

    2012-03-01

    Full Text Available We assess the consistency between instantaneously collocated level-2 aerosol optical depth (AOD retrievals from MODIS-Aqua (C5 and CALIOP (Version 2 & 3, comparing the standard MODIS AOD (MYD04_L2 data to the AOD calculated from CALIOP aerosol extinction profiles for both the previous release (V2 and the latest release (V3 of CALIOP data. Based on data collected in January 2007, we investigate the most useful criteria for screening the MODIS and CALIOP retrievals to achieve the best agreement between the two data sets. Applying these criteria to eight months of data (Jan, Apr, Jul, Oct 2007 and 2009, we find an order of magnitude increase for the CALIOP V3 data density (by comparison to V2, that is generally accompanied by equal or better agreement with MODIS AOD. Differences in global, monthly mean, over-ocean AOD (532 nm between CALIOP and MODIS range between 0.03 and 0.04 for CALIOP V3, with CALIOP generally biased low, when all available data from both sensors are considered. Root-mean-squares (RMS differences in instantaneously collocated AOD retrievals by the two instruments are reduced from values ranging between 0.14 and 0.19 using the unscreened V3 data to values ranging from 0.09 to 0.1 for the screened data. A restriction to scenes with cloud fractions less than 1% (as defined in the MODIS aerosol retrievals generally results in improved correlation (R2>0.5, except for the month of July when correlations remain relatively lower. Regional assessments show hot spots in disagreement between the two sensors in Asian outflow during April and off the coast of South Africa in July.

  3. On the Relative Stability of CERES Reflected Shortwave and MISR and MODIS Visible Radiance Measurements During the Terra Satellite Mission

    Science.gov (United States)

    Corbett, J. G.; Loeb, N. G.

    2015-01-01

    Fifteen years of visible, near-infrared, and broadband shortwave radiance measurements from Clouds and the Earth's Radiant Energy System (CERES), Multiangle Imaging Spectroradiometer (MISR), and Moderate Resolution Imaging Spectroradiometer (MODIS) instruments on board NASA's Terra satellite are analyzed in order to assess their long-term relative stability for climate purposes. A regression-based approach between CERES, MODIS, and MISR (An camera only) reflectances is used to calculate the bias between the different reflectances relative to a reference year. When compared to the CERES shortwave broadband reflectance, relative drift between the MISR narrowbands is within 1%/decade. Compared to the CERES shortwave reflectance, the MODIS narrowband reflectances show a relative drift of less than -1.33%/decade. When compared to MISR, the MODIS reflectances show a relative drift of between -0.36%/decade and -2.66%/decade. We show that the CERES Terra SW measurements are stable over the time period relative to CERES Aqua. Using this as evidence that CERES Terra may be absolutely stable, we suggest that the CERES, MISR, and MODIS instruments meet the radiometric stability goals for climate applications set out in Ohring et al. (2005).

  4. Evaluation of model simulated and MODIS-Aqua retrieved sea surface chlorophyll in the eastern Arabian Sea

    Science.gov (United States)

    Chakraborty, Kunal; Gupta, Anubhav; Lotliker, Aneesh A.; Tilstone, Gavin

    2016-11-01

    In this study we assess the accuracy of sea surface Chlorophyll-a (Chla) retrieved from satellite (MODIS-Aqua), using standard OC3M algorithm, and from a Regional Ocean Modelling System (ROMS) biophysical model against in situ data, measured in surface waters of the eastern Arabian Sea, from April 2009 to December 2012. MODIS-Aqua OC3M Chla concentrations showed a high correlation with the in situ data with slope close to unity and low root mean square error. In comparison, the ROMS model underestimated Chla, though the correlation was significant indicating that the model is capable of reproducing the trend in in situ Chla. Time Series trends in Chla were examined against wind driven Upwelling Indices (UIW) from April 2009 to December 2012 in north-eastern (Gujarat) and south-eastern (Kochi) coastal waters of the Arabian Sea. The annual peak in Chla along the Kochi coast during the summer monsoon was adequately captured by the model. It is well known that the peak in surface Chla along the Kochi and Gujarat coasts during the summer monsoon is the result of coastal upwelling, which the ROMS model was able to reproduce accurately. The maximum surface Chla along the Gujarat coast during the winter monsoon is due to convective mixing, which was also significantly captured by ROMS biophysical model. There was a lag of approximately one week between the maximum surface Chla and the peak in the Upwelling Index.

  5. Diffuse Attenuation Coef. K490, Aqua MODIS, NPP, 0.125 degrees, Gulf of Mexico

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NASA distributes Diffuse Attenuation Coefficient at 490 nm Wavelength data from NASA's Aqua satellite. Measurements are gathered by the Moderate Resolution Imaging...

  6. Chlorophyll-a, Aqua MODIS, NPP, 0.0125 degrees, Gulf of Mexico, EXPERIMENTAL

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA CoastWatch distributes chlorophyll-a concentration data from NASA's Aqua Spacecraft. Measurements are gathered by the Moderate Resolution Imaging...

  7. Diffuse Attenuation Coef. K490, Aqua MODIS, NPP, 0.05 degrees, Global, Science Quality

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NASA distributes Diffuse Attenuation Coefficient at 490 nm Wavelength data from NASA's Aqua satellite. Measurements are gathered by the Moderate Resolution Imaging...

  8. Chlorophyll-a, Aqua MODIS, OSU DB, 0.0125 degrees, West US

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA CoastWatch distributes chlorophyll-a concentration data from NASA's Aqua satellite. Measurements are gathered by the Moderate Resolution Imaging...

  9. Chlorophyll-a, Aqua MODIS, NPP, 0.0125 degrees, West US, EXPERIMENTAL

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA CoastWatch distributes chlorophyll-a concentration data from NASA's Aqua Spacecraft. Measurements are gathered by the Moderate Resolution Imaging...

  10. Chlorophyll-a, Aqua MODIS, NPP, 0.025 degrees, Pacific Ocean, EXPERIMENTAL

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA CoastWatch distributes chlorophyll-a concentration data from NASA's Aqua Spacecraft. Measurements are gathered by the Moderate Resolution Imaging...

  11. Chlorophyll-a, Aqua MODIS, NPP, 0.0125 degrees, East US, EXPERIMENTAL

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA CoastWatch distributes chlorophyll-a concentration data from NASA's Aqua Spacecraft. Measurements are gathered by the Moderate Resolution Imaging...

  12. Diffuse Attenuation Coef. K490, Aqua MODIS, 0.125 degrees, Indonesia

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — OSU distributes Diffuse Attenuation Coefficient at 490 nm Wavelength data from NASA's Aqua satellite. Measurements are gathered by the Moderate Resolution Imaging...

  13. Chlorophyll-a, Aqua MODIS, NPP, 0.0125 degrees, Indonesia

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA CoastWatch distributes chlorophyll-a concentration data from NASA's Aqua Spacecraft. Measurements are gathered by the Moderate Resolution Imaging...

  14. Chlorophyll-a, Aqua MODIS, NPP, 0.05 degrees, Global, Science Quality

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA CoastWatch distributes chlorophyll-a concentration data from NASA's Aqua Spacecraft. Measurements are gathered by the Moderate Resolution Imaging...

  15. Aerosol optical depth over central north Asia based on MODIS-Aqua data

    Science.gov (United States)

    Avgousta Foutsi, Athina; Korras Carraca, Marios Bruno; Matsoukas, Christos; Biskos, George

    2016-04-01

    Atmospheric aerosols, both natural and anthropogenic, can affect the regional and global climate through their direct, indirect, and semi-direct effects on the radiative energy budget of the Earth-atmosphere system. To quantify these effects it is important to determine the aerosol load, and an effective way to do that is by measuring the aerosol optical depth (AOD). The central Asia region (mainly the Caspian and Aral sea basins), the arid and semi-arid regions of Western China as well as Siberia are of great interest due to the significant natural sources of mineral aerosols originating from local deserts and biomass burning from wildfires in boreal forests. What is of particular interest in the region is the phenomenal shrinking and desertification of the Aral Sea that drives an intense salt and dust transport from the exposed sea-bed to the surrounding regions with important implications in regional air quality. Anthropogenic particles are also observed due to fossil-fuel combustion occurring mainly at oil refineries in the Caspian Sea basin. Here we investigate the spatial and temporal variability of the AOD at 550 nm over central Asia, Siberia and western China, in the region located between 35° N - 65° N and 45° E - 110° E. For our analysis we use Level-3 daily MODIS - Aqua Dark Target - Deep Blue combined product, from the latest collection (006), available in a 1°×1° resolution (ca. 100 km × 100 km) over the period 2002-2014. Our results indicate a significant spatial variability of the aerosol load over the study region. The highest AODs are observed over the Aral Sea year-round, with extreme values reaching 2.1 during July. In the rest of our study region a clear seasonal cycle with highest AOD values (up to 1.2 over the Taklamakan Desert) during spring and summer is observed. The arid parts of central north Asia are characterized by larger aerosol loads during spring, lower but still high AOD in summer and much lower values in autumn and spring

  16. Photosynthetically Available Radiation, Aqua MODIS, NPP, 0.125 degrees, Gulf of Mexico

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — MODIS measures photosynthetically available radiation that may be used to mode primary productivity. THIS IS AN EXPERIMENTAL PRODUCT: intended strictly for...

  17. Photosynthetically Available Radiation, Aqua MODIS, NPP, 0.125 degrees, East US

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — MODIS measures photosynthetically available radiation that may be used to mode primary productivity. THIS IS AN EXPERIMENTAL PRODUCT: intended strictly for...

  18. Fluorescence, Aqua MODIS, NPP, 0.05 degrees, West US, Science Quality

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — MODIS measures chlorophyll fluorescence, which gives insight into the physiology of phytoplankton in the ocean. When phytoplankton are under stress, the rate at...

  19. SST, Aqua MODIS, NPP, 0.0125 degrees, Gulf of Mexico, Day time (11 microns)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA CoastWatch provides SST data from NASA's Terra Spacecraft. Measurements are gathered by the Moderate Resolution Imaging Spectroradiometer (MODIS) carried...

  20. SST, Aqua MODIS, NPP, 0.0125 degrees, Gulf of Mexico, Day and Night

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA CoastWatch provides SST data from NASA's Terra Spacecraft. Measurements are gathered by the Moderate Resolution Imaging Spectroradiometer (MODIS) carried...

  1. Chromophoric Dissolved Organic Material, Aqua MODIS, NPP, 0.125 degrees, East US

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — MODIS data is used to develop an index of the amount of chromophoric dissolved organic material (CDOM) in the surface waters. CDOM absorbs heavily in the blue...

  2. SST, Aqua MODIS, NPP, 0.0125 degrees, Gulf of Mexico, Night time (4 microns)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA CoastWatch provides SST data from NASA's Terra Spacecraft. Measurements are gathered by the Moderate Resolution Imaging Spectroradiometer (MODIS) carried...

  3. Photosynthetically Available Radiation, Aqua MODIS, NPP, 0.125 degrees, West US

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — MODIS measures photosynthetically available radiation that may be used to mode primary productivity. THIS IS AN EXPERIMENTAL PRODUCT: intended strictly for...

  4. Photosynthetically Available Radiation, Aqua MODIS, NPP, 0.05 degrees, Global, Science Quality

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — MODIS measures photosynthetically available radiation that may be used to mode primary productivity. THIS IS AN EXPERIMENTAL PRODUCT: intended strictly for...

  5. MODIS/AQUA MYD13A3 Vegetation Indices Monthly L3 Global 1km

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Global MODIS vegetation indices are designed to provide consistent spatial and temporal comparisons of vegetation conditions. Blue, red, and near-infrared...

  6. Chromophoric Dissolved Organic Material, Aqua MODIS, NPP, 0.05 degrees, Global, Science Quality

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — MODIS data is used to develop an index of the amount of chromophoric dissolved organic material (CDOM) in the surface waters. CDOM absorbs heavily in the blue...

  7. MODIS/AQUA MYD13A2 Vegetation Indices 16-Day L3 Global 1km

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Global MODIS vegetation indices are designed to provide consistent spatial and temporal comparisons of vegetation conditions. Blue, red, and near-infrared...

  8. MODIS/AQUA MYD13Q1 Vegetation Indices 16-Day L3 Global 250m

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Global MODIS vegetation indices are designed to provide consistent spatial and temporal comparisons of vegetation conditions. Blue, red, and near-infrared...

  9. Chromophoric Dissolved Organic Material, Aqua MODIS, NPP, 0.125 degrees, West US

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — MODIS data is used to develop an index of the amount of chromophoric dissolved organic material (CDOM) in the surface waters. CDOM absorbs heavily in the blue...

  10. MODIS/AQUA MYD13A1 Vegetation Indices 16-Day L3 Global 500m

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Global MODIS vegetation indices are designed to provide consistent spatial and temporal comparisons of vegetation conditions. Blue, red, and near-infrared...

  11. Characterization of turbidity in Florida's Lake Okeechobee and Caloosahatchee and St. Lucie estuaries using MODIS-Aqua measurements.

    Science.gov (United States)

    Wang, Menghua; Nim, Carl J; Son, Seunghyun; Shi, Wei

    2012-10-15

    This paper describes the use of ocean color remote sensing data from the Moderate Resolution Imaging Spectroradiometer (MODIS) onboard the Aqua satellite to characterize turbidity in Lake Okeechobee and its primary drainage basins, the Caloosahatchee and St. Lucie estuaries from 2002 to 2010. Drainage modification and agricultural development in southern Florida transport sediments and nutrients from watershed agricultural areas to Lake Okeechobee. As a result of development around Lake Okeechobee and the estuaries that are connected to Lake Okeechobee, estuarine conditions have also been adversely impacted, resulting in salinity and nutrient fluctuations. The measurement of water turbidity in lacustrine and estuarine ecosystems allows researchers to understand important factors such as light limitation and the potential release of nutrients from re-suspended sediments. Based on a strong correlation between water turbidity and normalized water-leaving radiance at the near-infrared (NIR) band (nL(w)(869)), a new satellite water turbidity algorithm has been developed for Lake Okeechobee. This study has shown important applications with satellite-measured nL(w)(869) data for water quality monitoring and measurements for turbid inland lakes. MODIS-Aqua-measured water property data are derived using the shortwave infrared (SWIR)-based atmospheric correction algorithm in order to remotely obtain synoptic turbidity data in Lake Okeechobee and normalized water-leaving radiance using the red band (nL(w)(645)) in the Caloosahatchee and St. Lucie estuaries. We found varied, but distinct seasonal, spatial, and event driven turbidity trends in Lake Okeechobee and the Caloosahatchee and St. Lucie estuary regions. Wind waves and hurricanes have the largest influence on turbidity trends in Lake Okeechobee, while tides, currents, wind waves, and hurricanes influence the Caloosahatchee and St. Lucie estuarine areas.

  12. Reconstruction of MODIS Spectral Reflectance under Cloudy-Sky Condition

    Directory of Open Access Journals (Sweden)

    Bo Gao

    2016-09-01

    Full Text Available Clouds usually cause invalid observations for sensors aboard satellites, which corrupts the spatio-temporal continuity of land surface parameters retrieved from remote sensing data (e.g., MODerate Resolution Imaging Spectroradiometer (MODIS data and prevents the fusing of multi-source remote sensing data in the field of quantitative remote sensing. Based on the requirements of spatio-temporal continuity and the necessity of methods to restore bad pixels, primarily resulting from image processing, this study developed a novel method to derive the spectral reflectance for MODIS band of cloudy pixels in the visual–near infrared (VIS–NIR spectral channel based on the Bidirectional Reflectance Distribution Function (BRDF and multi-spatio-temporal observations. The proposed method first constructs the spatial distribution of land surface reflectance based on the corresponding BRDF and the solar-viewing geometry; then, a geographically weighted regression (GWR is introduced to individually derive the spectral surface reflectance for MODIS band of cloudy pixels. A validation of the proposed method shows that a total root-mean-square error (RMSE of less than 6% and a total R2 of more than 90% are detected, which indicates considerably better precision than those exhibited by other existing methods. Further validation of the retrieved white-sky albedo based on the spectral reflectance for MODIS band of cloudy pixels confirms an RMSE of 3.6% and a bias of 2.2%, demonstrating very high accuracy of the proposed method.

  13. Inferences of all-sky solar irradiance using Terra and Aqua MODIS satellite data

    DEFF Research Database (Denmark)

    Houborg, Rasmus Møller; Søgaard, Henrik; Emmerich, W.;

    2007-01-01

    contrasting climates and cloud environments. Information on the atmospheric state was provided by MODIS data products and verifications against AErosol RObotic NETwork (AERONET) data demonstrated usefulness of MODIS aerosol optical depth and total precipitable water vapour retrievals for the delineation......) and 26.6% (72 W m-2) for Southern Arizona and the Island of Zealand, respectively. For both regions, hourly satellite estimates were shown to be more reliable than pyranometer measurements from ground stations only 15 km away from the point of interest, which is comparable to the accuracy level...

  14. Quality Assessment of Landsat Surface Reflectance Products Using MODIS Data

    Science.gov (United States)

    Feng, Min; Huang, Chengquan; Channan, Saurabh; Vermote, Eric; Masek, Jeffrey G.; Townshend, John R.

    2012-01-01

    Surface reflectance adjusted for atmospheric effects is a primary input for land cover change detection and for developing many higher level surface geophysical parameters. With the development of automated atmospheric correction algorithms, it is now feasible to produce large quantities of surface reflectance products using Landsat images. Validation of these products requires in situ measurements, which either do not exist or are difficult to obtain for most Landsat images. The surface reflectance products derived using data acquired by the Moderate Resolution Imaging Spectroradiometer (MODIS), however, have been validated more comprehensively. Because the MODIS on the Terra platform and the Landsat 7 are only half an hour apart following the same orbit, and each of the 6 Landsat spectral bands overlaps with a MODIS band, good agreements between MODIS and Landsat surface reflectance values can be considered indicators of the reliability of the Landsat products, while disagreements may suggest potential quality problems that need to be further investigated. Here we develop a system called Landsat-MODIS Consistency Checking System (LMCCS). This system automatically matches Landsat data with MODIS observations acquired on the same date over the same locations and uses them to calculate a set of agreement metrics. To maximize its portability, Java and open-source libraries were used in developing this system, and object-oriented programming (OOP) principles were followed to make it more flexible for future expansion. As a highly automated system designed to run as a stand-alone package or as a component of other Landsat data processing systems, this system can be used to assess the quality of essentially every Landsat surface reflectance image where spatially and temporally matching MODIS data are available. The effectiveness of this system was demonstrated using it to assess preliminary surface reflectance products derived using the Global Land Survey (GLS) Landsat

  15. Quality assessment of Landsat surface reflectance products using MODIS data

    Science.gov (United States)

    Feng, Min; Huang, Chengquan; Channan, Saurabh; Vermote, Eric F.; Masek, Jeffrey G.; Townshend, John R.

    2012-01-01

    Surface reflectance adjusted for atmospheric effects is a primary input for land cover change detection and for developing many higher level surface geophysical parameters. With the development of automated atmospheric correction algorithms, it is now feasible to produce large quantities of surface reflectance products using Landsat images. Validation of these products requires in situ measurements, which either do not exist or are difficult to obtain for most Landsat images. The surface reflectance products derived using data acquired by the Moderate Resolution Imaging Spectroradiometer (MODIS), however, have been validated more comprehensively. Because the MODIS on the Terra platform and the Landsat 7 are only half an hour apart following the same orbit, and each of the 6 Landsat spectral bands overlaps with a MODIS band, good agreements between MODIS and Landsat surface reflectance values can be considered indicators of the reliability of the Landsat products, while disagreements may suggest potential quality problems that need to be further investigated. Here we develop a system called Landsat-MODIS Consistency Checking System (LMCCS). This system automatically matches Landsat data with MODIS observations acquired on the same date over the same locations and uses them to calculate a set of agreement metrics. To maximize its portability, Java and open-source libraries were used in developing this system, and object-oriented programming (OOP) principles were followed to make it more flexible for future expansion. As a highly automated system designed to run as a stand-alone package or as a component of other Landsat data processing systems, this system can be used to assess the quality of essentially every Landsat surface reflectance image where spatially and temporally matching MODIS data are available. The effectiveness of this system was demonstrated using it to assess preliminary surface reflectance products derived using the Global Land Survey (GLS) Landsat

  16. Climatology and trends of aerosol optical depth over the Mediterranean basin during the last 12years (2002-2014) based on Collection 006 MODIS-Aqua data.

    Science.gov (United States)

    Floutsi, A A; Korras-Carraca, M B; Matsoukas, C; Hatzianastassiou, N; Biskos, G

    2016-05-01

    The Mediterranean basin is a region of particular interest for studying atmospheric aerosols due to the large variety of air masses it receives, and its sensitivity to climate change. In this study we use the newest collection (C006) of aerosol optical depth from MODIS-Aqua, from which we also derived the fine-mode fraction and Ångström exponent over the last 12years (i.e., from 2002 to 2014), providing the longest analyzed dataset for this region. The long-term regional optical depth average is 0.20±0.05, with the indicated uncertainty reflecting the inter-annual variability. Overall, the aerosol optical depth exhibits a south-to-north decreasing gradient and an average decreasing trend of 0.0030 per year (19% total decrease over the study period). The correlation between the reported AOD observations with measurements from the ground AERONET stations is high (R=0.76-0.80 depending on the wavelength), with the MODIS-Aqua data being slightly overestimated. Both fine-fraction and Ångström exponent data highlight the dominance of anthropogenic aerosols over the northern, and of desert aerosols over the southern part of the region. Clear intrusions of desert dust over the Eastern Mediterranean are observed principally in spring, and in some cases in winter. Dust intrusions dominate the Western Mediterranean in the summer (and sometimes in autumn), whereas anthropogenic aerosols dominate the sub-region of the Black Sea in all seasons but especially during summer. Fine-mode optical depth is found to decrease over almost all areas of the study region during the 12-year period, marking the decreasing contribution of anthropogenic particulate matter emissions over the study area. Coarse-mode aerosol load also exhibits an overall decreasing trend. However, its decrease is smaller than that of fine aerosols and not as uniformly distributed, underlining that the overall decrease in the region arises mainly from reduced anthropogenic emissions. PMID:26878641

  17. Data Assimilation of the High-Resolution Sea Surface Temperature Obtained from the Aqua-Terra Satellites (MODIS-SST) Using an Ensemble Kalman Filter

    OpenAIRE

    Takuji Waseda; Varlamov, Sergey M.; Xinyu Guo; Hiroshi Murakami; Toru Miyama; Sourav Sil; Yasumasa Miyazawa

    2013-01-01

    We develop an assimilation method of high horizontal resolution sea surface temperature data, provided from the Moderate Resolution Imaging Spectroradiometer (MODIS-SST) sensors boarded on the Aqua and Terra satellites operated by National Aeronautics and Space Administration (NASA), focusing on the reproducibility of the Kuroshio front variations south of Japan in February 2010. Major concerns associated with the development are (1) negative temperature bias due to the cloud effects, and (2)...

  18. A surface reflectance scheme for retrieving aerosol optical depth over urban surfaces in MODIS Dark Target retrieval algorithm

    Science.gov (United States)

    Gupta, Pawan; Levy, Robert C.; Mattoo, Shana; Remer, Lorraine A.; Munchak, Leigh A.

    2016-07-01

    The MODerate resolution Imaging Spectroradiometer (MODIS) instruments, aboard the two Earth Observing System (EOS) satellites Terra and Aqua, provide aerosol information with nearly daily global coverage at moderate spatial resolution (10 and 3 km). Almost 15 years of aerosol data records are now available from MODIS that can be used for various climate and air-quality applications. However, the application of MODIS aerosol products for air-quality concerns is limited by a reduction in retrieval accuracy over urban surfaces. This is largely because the urban surface reflectance behaves differently than that assumed for natural surfaces. In this study, we address the inaccuracies produced by the MODIS Dark Target (MDT) algorithm aerosol optical depth (AOD) retrievals over urban areas and suggest improvements by modifying the surface reflectance scheme in the algorithm. By integrating MODIS Land Surface Reflectance and Land Cover Type information into the aerosol surface parameterization scheme for urban areas, much of the issues associated with the standard algorithm have been mitigated for our test region, the continental United States (CONUS). The new surface scheme takes into account the change in underlying surface type and is only applied for MODIS pixels with urban percentage (UP) larger than 20 %. Over the urban areas where the new scheme has been applied (UP > 20 %), the number of AOD retrievals falling within expected error (EE %) has increased by 20 %, and the strong positive bias against ground-based sun photometry has been eliminated. However, we note that the new retrieval introduces a small negative bias for AOD values less than 0.1 due to the ultra-sensitivity of the AOD retrieval to the surface parameterization under low atmospheric aerosol loadings. Global application of the new urban surface parameterization appears promising, but further research and analysis are required before global implementation.

  19. GLOBAL LAND COVER CLASSIFICATION USING MODIS SURFACE REFLECTANCE PROSUCTS

    OpenAIRE

    Fukue, Kiyonari; Shimoda, Haruhisa

    2016-01-01

    The objective of this study is to develop high accuracy land cover classification algorithm for Global scale by using multi-temporal MODIS land reflectance products. In this study, time-domain co-occurrence matrix was introduced as a classification feature which provides time-series signature of land covers. Further, the non-parametric minimum distance classifier was introduced for timedomain co-occurrence matrix, which performs multi-dimensional pattern matching for time-domain co-o...

  20. GLOBAL LAND COVER CLASSIFICATION USING MODIS SURFACE REFLECTANCE PRODUCTS

    OpenAIRE

    Shimoda, H; K. Fukue

    2012-01-01

    The objective of this study is to develop high accuracy land cover classification algorithm for Global scale by using multi-temporal MODIS land reflectance products. In this study, time-domain co-occurrence matrix was introduced as a classification feature which provides time-series signature of land covers. Further, the non-parametric minimum distance classifier was introduced for timedomain co-occurrence matrix, which performs multi-dimensional pattern matching for time-domain co-o...

  1. Downscaling MODIS Surface Reflectance to Improve Water Body Extraction

    Directory of Open Access Journals (Sweden)

    Xianghong Che

    2015-01-01

    Full Text Available Inland surface water is essential to terrestrial ecosystems and human civilization. Accurate mapping of surface water dynamic is vital for both scientific research and policy-driven applications. MODIS provides twice observation per day, making it perfect for monitoring temporal water dynamic. Although MODIS provides two bands at 250 m resolution, accurately deriving water area always depends on observations from the spectral bands with 500 m resolution, which limits its discrimination ability over small lakes and rivers. The paper presents an automated method for downscaling the 500 m MODIS surface reflectance (SR to 250 m to improve the spatial discrimination of water body extraction. The method has been tested at Co Ngoin and Co Bangkog in Qinghai-Tibet plateau. The downscaled SR and the derived water bodies were compared to SR and water body mapped from Landsat-7 ETM+ images were acquired on the same date. Consistency metrics were calculated to measure their agreement and disagreement. The comparisons indicated that the downscaled MODIS SR showed significant improvement over the original 500 m observations when compared with Landsat-7 ETM+ SR, and both commission and omission errors were reduced in the derived 250 m water bodies.

  2. Winter wheat leaf area index retrieval with multi-angle and multi-spectral Terra/Aqua MODIS data%联合Terra/Aqua MODIS多角度多光谱数据反演冬小麦叶面积指数

    Institute of Scientific and Technical Information of China (English)

    何维; 杨华

    2013-01-01

      Terra 与 Aqua 双星搭载的 MODIS 传感器可实现每日上下午分别对同一地点观测一次,并且由于卫星轨道漂移形成累积连续多天的多角度观测特点,加上多通道的光谱响应,极大地丰富了地表目标的观测信息,为 LAI等地表参数的实时准确反演提供了可能。该文利用 MODIS 双星高质量的连续多天的多波段地表反射率数据,结合 PROSAIL(PROSPECT+SAIL,properties spectra + scattering by arbitrarily inclined leaves)模型和查找表方法反演冬小麦 LAI,并与 MODIS LAI 产品及野外采样点实测 LAI 对比,结果表明,联合双星高质量的多角度多波段数据能够较准确反演冬小麦 LAI,其反演结果无论从空间分布还是时序变化特征来讲,较 MODIS LAI 产品更符合实际情况,也更接近地面实测值。该文的研究为充分利用 MODIS 数据的角度和光谱信息反演小麦等农作物的 LAI提供了一定的借鉴。%MODIS sensors, carried onboard Terra and Aqua satellites, scan the same location daily at a fixed time. Because of the sequential multidirectional information contributed by satellite orbit drift along with multi-channel spectral responses, MODIS data greatly enriches the observations of land surface targets, which makes it possible to estimate the land surface parameters accurately and timely, such as leaf area index (LAI). Many researchers have focused on LAI estimation using MODIS data, among whom most used the multispectral data of a single satellite in one day or eight days, while few comprehensively utilized the multispectral and multidirectional information obtained by the both MODIS sensors in some sequence of days. MODIS LAI products have developed a series of generations, the fifth version (MODIS V005) has integrated data from both Terra and Aqua. It is proven that this version is improved with single satellite data, however, it only utilizes red and near-infrared band observations. It has been suggested

  3. A surface reflectance scheme for retrieving aerosol optical depth over urban surfaces in MODIS dark target retrieval algorithm

    OpenAIRE

    Gupta, P.; R. C. Levy; S. Mattoo; L. A. Remer; L. A. Munchak

    2016-01-01

    The MODerate resolution Imaging Spectroradiometer (MODIS) instruments, aboard two Earth Observing Satellites (EOS) Terra and Aqua, provide aerosol information with nearly daily global coverage at moderate spatial resolution (10 km and 3 km). Almost 15 years of aerosol data records are now available from MODIS that can be used for various climate and air quality applications. However, the application of MODIS aerosol products for air quality concerns is limited by a reduction in retrieval accu...

  4. Global Land Cover Classification Using Modis Surface Reflectance Prosucts

    Science.gov (United States)

    Fukue, Kiyonari; Shimoda, Haruhisa

    2016-06-01

    The objective of this study is to develop high accuracy land cover classification algorithm for Global scale by using multi-temporal MODIS land reflectance products. In this study, time-domain co-occurrence matrix was introduced as a classification feature which provides time-series signature of land covers. Further, the non-parametric minimum distance classifier was introduced for timedomain co-occurrence matrix, which performs multi-dimensional pattern matching for time-domain co-occurrence matrices of a classification target pixel and each classification classes. The global land cover classification experiments have been conducted by applying the proposed classification method using 46 multi-temporal(in one year) SR(Surface Reflectance) and NBAR(Nadir BRDF-Adjusted Reflectance) products, respectively. IGBP 17 land cover categories were used in our classification experiments. As the results, SR and NBAR products showed similar classification accuracy of 99%.

  5. AIRS Pixel Cloud Detection Based on MODIS Cloud Products on Aqua Satellite%EOS卫星上基于MODIS云产品的AIRS像素云检测

    Institute of Scientific and Technical Information of China (English)

    王丹凤; 张记龙; 王志斌; 陈媛媛; 陈友华

    2012-01-01

    联合使用搭载在地球观测系统(EOS) Aqua卫星上的中分辨力成像光谱仪MODIS和大气红外探测器AIRS,能够提高对全球云量分布情况的检测.利用几何扫描特性的空间匹配算法,MODIS云分类掩膜和云相态掩膜产品,结合业务上的云检测算法,实现了用空间匹配的MODIS数据对AIRS像素云特性的检测.结果表明,用MODIS 1 km分辨力产品可以鉴别出AIRS像素中不同的云类型、云层信息(低云、中云或者高云)和云相态信息(水云、冰云或者混合相态信息).%The combined systems of the Moderate Resolution Imaging Spectroradiometer(MODIS) and the Atmospheric Infrared Sounder (AIRS) measurements from the Earth Observing System's (EOS's) Aqua satellite enable improve global monitoring of the distribution of clouds. Using the space collocation algorithms based on the scanning geometry, MODIS cloud phase mask, MODIS classification mask, also combing with the operational algorithm of MODIS cloud retrieval, the function of testing AIRS Subpixel Cloud Characterization based on space collocationed of MODIS data is realized. The results show that MODIS 1 km-spatial-resolution data is applied to identify various cloud types. Cloud-layer information(lower, midlevel, or high clouds) and phase information (water,ice,or mixed-phase clouds)within an AIRS footprint.

  6. Alternative method of on-orbit response-versus-scan-angle characterization for MODIS reflective solar bands

    Science.gov (United States)

    Chen, Hongda; Xiong, Xiaoxiong; Angal, Amit; Geng, Xu; Wu, Aisheng

    2016-04-01

    The moderate resolution imaging spectroradiometer (MODIS) has 20 reflective solar bands (RSB), covering a spectral range from 0.41 to 2.2 μm, which are calibrated on-orbit using its onboard calibrators, which include a solar diffuser, a solar diffuser stability monitor, and a spectroradiometric calibration assembly. A space view (SV) port is used to provide a background reference and also facilitates near-monthly lunar observations through a spacecraft roll. In every scan, the Earth's surface, SV, and onboard calibrators are viewed via a two-sided scan mirror, the reflectance of which depends on the angle of incidence (AOI) as well as the wavelength of the incident light. Response-versus-scan-angle (RVS) is defined as a dependence function of the scan mirror's reflectance over AOI. An initial RVS for each RSB was measured prelaunch for both Terra and Aqua MODIS. Algorithms have been developed to track the on-orbit RVS variation using the measurements from the onboard calibrators, supplemented with the earth view (EV) trends from pseudoinvariant desert targets obtained at different AOI. Since the mission beginning, the MODIS characterization support team (MCST) has dedicated efforts in evaluating approaches of characterizing the on-orbit RVS. A majority of the approaches focused on fitting the data at each AOI over time and then deriving the relative change at different AOI. The current version of the on-orbit RVS algorithm, as implemented in the collection 6 (C6) level-1B (L1B), is also based on the above rationale. It utilizes the EV response trends from the pseudoinvariant Libyan desert targets to supplement the gain derived from the onboard calibrators. The primary limitation of this approach is the assumption of the temporal stability of these desert sites. Consequently, MCST developed an approach that derives the on-orbit RVS change using measurements from a single desert site, combined with the on-orbit lunar measurements. In addition, the EV and onboard

  7. Alternative Method of On-Orbit Response-Versus-Scan-Angle Characterization for MODIS Reflective Solar Bands

    Science.gov (United States)

    Chen, Hongda; Xiong, Xiaoxiong; Angal, Amit; Geng, Xu; Wu, Aisheng

    2016-01-01

    The moderate resolution imaging spectroradiometer (MODIS) has 20 reflective solar bands (RSB), covering a spectral range from 0.41 to 2.2 microns, which are calibrated on-orbit using its onboard calibrators, which include a solar diffuser, a solar diffuser stability monitor, and a spectroradiometric calibration assembly. A space view (SV) port is used to provide a background reference and also facilitates near-monthly lunar observations through a spacecraft roll. In every scan, the Earth's surface, SV, and onboard calibrators are viewed via a two-sided scan mirror, the reflectance of which depends on the angle of incidence (AOI) as well as the wavelength of the incident light. Response-versus-scan-angle (RVS) is defined as a dependence function of the scan mirror's reflectance over AOI. An initial RVS for each RSB was measured prelaunch for both Terra and Aqua MODIS. Algorithms have been developed to track the on-orbit RVS variation using the measurements from the onboard calibrators, supplemented with the earth view (EV) trends from pseudoinvariant desert targets obtained at different AOI. Since the mission beginning, the MODIS characterization support team (MCST) has dedicated efforts in evaluating approaches of characterizing the on-orbit RVS. A majority of the approaches focused on fitting the data at each AOI over time and then deriving the relative change at different AOI. The current version of the on-orbit RVS algorithm, as implemented in the collection 6 (C6) level-1B (L1B), is also based on the above rationale. It utilizes the EV response trends from the pseudoinvariant Libyan desert targets to supplement the gain derived from the onboard calibrators. The primary limitation of this approach is the assumption of the temporal stability of these desert sites. Consequently, MCST developed an approach that derives the on-orbit RVS change using measurements from a single desert site, combined with the on-orbit lunar measurements. In addition, the EV and onboard

  8. Evaluation of BRDF Archetypes for Representing Surface Reflectance Anisotropy Using MODIS BRDF Data

    OpenAIRE

    Hu Zhang; Ziti Jiao; Yadong Dong; Xiaowen Li

    2015-01-01

    Bidirectional reflectance distribution function (BRDF) archetypes extracted from the Moderate Resolution Imaging Spectroradiometer (MODIS) BRDF/Albedo product over the global Earth Observing System Land Validation Core Sites can be used to simplify BRDF models. The present study attempts to evaluate the representativeness of BRDF archetypes for surface reflectance anisotropy. Five-year forward-modeled MODIS multi-angular reflectance (MCD-ref) and aditional actual MODIS multi-angular observat...

  9. MODIS/AQUA MYD14A2 Thermal Anomalies & Fire 8-Day L3 Global 1km

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — MODIS Thermal Anomalies/Fire products are primarily derived from MODIS 4- and 11-micrometer radiances. The fire detection strategy is based on absolute detection of...

  10. MODIS/AQUA MYD14A2 Thermal Anomalies & Fire 8-Day L3 Global 1km Version 6

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — MODIS Thermal Anomalies/Fire products are primarily derived from MODIS 4- and 11-micrometer radiances. The fire detection strategy is based on absolute detection of...

  11. MODIS/AQUA MYD14 Thermal Anomalies & Fire 5-Min L2 Swath 1km Version 6

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — MODIS Thermal Anomalies/Fire products are primarily derived from MODIS 4- and 11-micrometer radiances. The fire detection strategy is based on absolute detection of...

  12. MODIS/AQUA MYD14A1 Thermal Anomalies & Fire Daily L3 Global 1km Version 6

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — MODIS Thermal Anomalies/Fire products are primarily derived from MODIS 4- and 11-micrometer radiances. The fire detection strategy is based on absolute detection of...

  13. Drought Monitoring and Category of Vegetation Temperature Condition Index Using Aqua-MODIS Data%基于Aqua-MODIS数据的条件植被温度指数干旱等级监测研究

    Institute of Scientific and Technical Information of China (English)

    林巧; 王鹏新; 张树誉; 刘峻明; 李俐

    2014-01-01

    以陕西关中平原为研究区域,选取2003年~2012年每年3月~5月的Aqua-MODIS数据,计算MODIS-VTCI干旱监测结果,通过气象数据对结果进行验证,对比MODIS和AVHRR数据多年同一旬的VTCI干旱监测及等级划分结果,发现两种监测结果反映出的旱情分布规律相同.MODIS-VTCI干旱监测结果表明,2003年、2004年、2005年和2009年关中地区春旱严重,其中3月中旬至4月下旬旱情发生频率较高.2009年MODIS-VTCI干旱等级监测结果表明,关中地区2009年3月中旬、4月上旬和中旬干旱程度严重,且关中东部地区旱情比西部严重.

  14. Prediksi Zona Tangkapan Ikan Menggunakan Citra Klorofil-a Dan Citra Suhu Permukaan Laut Satelit Aqua MODIS Di Perairan Pulo Aceh

    Directory of Open Access Journals (Sweden)

    Mursyidin Mursyidin

    2015-12-01

    prediction of fishing zone can be done by detecting chlorophyll-a and sea surface temperature distribution of Aqua MODIS Imagery. The aim of this study is to predict fishing zone on the waters of Pulo Aceh based on the chlorophyll distribution and sea surface temperature by utilizing the data of Aqua MODIS Satellite Imagery level 3. The stages of this study included collecting imagery, cutting the image according to the desired area, giving lands mark to display a more informative image, extracting information of chlorophyll-a and the distribution of sea surface temperature, and interpolating by using Kriging method. The highest distribution of chlorophyll-a happened in June and August, the spread moved from the the North Pulo Aceh to the South. The distribution of sea surface temperature that suitable for fishing was detected in August around the North Ujung Pulo Breuh and around pulau Keureusik. The potential zone of fishing on the waters of Pulo Aceh was only detected in August in the eastern of pulau Keureusik to Ujong Keumuroh. Pulo Aceh waters is suitable for fishing destination in August.

  15. A Semi-Analytic Model for Estimating Total Suspended Sediment Concentration in Turbid Coastal Waters of Northern Western Australia Using MODIS-Aqua 250 m Data

    Directory of Open Access Journals (Sweden)

    Passang Dorji

    2016-06-01

    Full Text Available Knowledge of the concentration of total suspended sediment (TSS in coastal waters is of significance to marine environmental monitoring agencies to determine the turbidity of water that serve as a proxy to estimate the availability of light at depth for benthic habitats. TSS models applicable to data collected by satellite sensors can be used to determine TSS with reasonable accuracy and of adequate spatial and temporal resolution to be of use for coastal water quality monitoring. Thus, a study is presented here where we develop a semi-analytic sediment model (SASM applicable to any sensor with red and near infrared (NIR bands. The calibration and validation of the SASM using bootstrap and cross-validation methods showed that the SASM applied to Moderate Resolution Imaging Spectroradiometer (MODIS-Aqua band 1 data retrieved TSS with a root mean square error (RMSE and mean averaged relative error (MARE of 5.75 mg/L and 33.33% respectively. The application of the SASM over our study region using MODIS-Aqua band 1 data showed that the SASM can be used to monitor the on-going, post and pre-dredging activities and identify daily TSS anomalies that are caused by natural and anthropogenic processes in coastal waters of northern Western Australia.

  16. MODIS/TERRA MOD09A1 Surface Reflectance 8-Day L3 Global 500m

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The MODIS Surface Reflectance products provide an estimate of the surface spectral reflectance as it would be measured at ground level in the absence of atmospheric...

  17. MODIS/TERRA MOD09GQ Surface Reflectance Daily L2G Global 250m

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The MODIS Surface Reflectance products provide an estimate of the surface spectral reflectance as it would be measured at ground level in the absence of atmospheric...

  18. MODIS/TERRA MOD09Q1 Surface Reflectance 8-Day L3 Global 250m

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The MODIS Surface Reflectance products provide an estimate of the surface spectral reflectance as it would be measured at ground level in the absence of atmospheric...

  19. MYDTBGA: MODIS/AQUA Thermal Bands Daily L2G Global 1 km SIN Grid Version 6

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The Version 6 MODIS Level 2 Gridded (L2G) Thermal Band product consists of brightness temperature data from MODIS bands 20, 31, and 32 and albedo data from band 20...

  20. MODIS/AQUA MYD13C2 Vegetation Indices Monthly L3 Global 0.05Deg CMG Version 6

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The MODIS Vegetation Indices Version 6 product provides a Vegetation Index (VI) value at a per pixel basis. There are 2 primary vegetation layers. The algorithm for...

  1. MODIS/Aqua MYD11A1 Land Surface Temperature and Emissivity Daily L3 Global 1 km Grid SIN

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The MODIS/Terra Land Surface Temperature and Emissivity (LST/E) products provide per-pixel temperature and emissivity values in a sequence of swath-based to...

  2. MODIS/AQUA MYD17A2 Gross Primary Productivity 8-Day L4 Global 1km

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The MODerate-resolution Imaging Spectroradiometer (MODIS) Gross Primary Productivity (GPP) products are a cumulative composite of GPP values based on the radiation...

  3. MODIS/AQUA MYD13C1 Vegetation Indices 16-Day L3 Global 0.05Deg CMG

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Global MODIS vegetation indices are designed to provide consistent spatial and temporal comparisons of vegetation conditions. Blue, red, and near-infrared...

  4. MODIS/AQUA MYD13C2 Vegetation Indices Monthly L3 Global 0.05Deg CMG

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Global MODIS vegetation indices are designed to provide consistent spatial and temporal comparisons of vegetation conditions. Blue, red, and near-infrared...

  5. MODIS/AQUA MYD13A1 Vegetation Indices 16-Day L3 Global 500m Version 6

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The MODIS Vegetation Indices Version 6 product provides a Vegetation Index (VI) value at a per pixel basis. There are 2 primary vegetation layers. The algorithm for...

  6. MODIS/AQUA MYD13A3 Vegetation Indices Monthly L3 Global 1km Version 6

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The MODIS Vegetation Indices Version 6 product provides a Vegetation Index (VI) value at a per pixel basis. There are 2 primary vegetation layers. The algorithm for...

  7. MODIS/AQUA MYD13Q1 Vegetation Indices 16-Day L3 Global 250m Version 6

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The MODIS Vegetation Indices Version 6 product provides a Vegetation Index (VI) value at a per pixel basis. There are 2 primary vegetation layers. The algorithm for...

  8. MODIS/AQUA MYD13A2 Vegetation Indices 16-Day L3 Global 1km Version 6

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The MODIS Vegetation Indices Version 6 product provides a Vegetation Index (VI) value at a per pixel basis. There are 2 primary vegetation layers. The algorithm for...

  9. MODIS/Aqua 8-Day Clear Sky Radiance Bias Daily L3 Global 1Deg Zonal Bands V006

    Data.gov (United States)

    National Aeronautics and Space Administration — MODIS 8-day clear-sky radiance bias (observed - calculated) statistics are provided for 1Deg latitudinal zones and selected thermal bands. Separation by day and...

  10. Evaluation of BRDF Archetypes for Representing Surface Reflectance Anisotropy Using MODIS BRDF Data

    Directory of Open Access Journals (Sweden)

    Hu Zhang

    2015-06-01

    Full Text Available Bidirectional reflectance distribution function (BRDF archetypes extracted from the Moderate Resolution Imaging Spectroradiometer (MODIS BRDF/Albedo product over the global Earth Observing System Land Validation Core Sites can be used to simplify BRDF models. The present study attempts to evaluate the representativeness of BRDF archetypes for surface reflectance anisotropy. Five-year forward-modeled MODIS multi-angular reflectance (MCD-ref and aditional actual MODIS multi-angular observations (MCD-obs in four growing periods in 2008 over three tiles were taken as validation data. First, BRDF archetypes in the principal plane were qualitatively compared with the time-series MODIS BRDF product of randomly sampled pixels. Secondly, BRDF archetypes were used to fit MCD-ref, and the average root-mean-squared errors (RMSEs over each tile were examined for these five years. Finally, both BRDF archetypes and the MODIS BRDF were used to fit MCD-obs, and the histograms of the fit-RMSEs were compared. The consistency of the directional reflectance between the BRDF archetypes and MODIS BRDFs in nadir-view, hotspot and entire viewing hemisphere at 30° and 50° solar geometries were also examined. The results confirm that BRDF archetypes are representative of surface reflectance anisotropy for available snow-free MODIS data.

  11. Improved retrieval of aerosol optical thickness from MODIS measurements through derived surface reflectance over Nanjing, China

    Energy Technology Data Exchange (ETDEWEB)

    Yong, Zha; Jianjun, Jiang; Heng, Lu; Jiazhu, Huang (Key Laboratory of Virtual Geographic Environment, Ministry of Education, College of Geographic Science, Nanjing Normal Univ., Nanjing (China)), e-mail: yzha@njnu.edu.cn; Qiao, Wang (Satellite Environment Center, Ministry of Environmental Protection, Beijing (China)); Jie, Yuan (Shaanxi Bureau of Surveying and Mapping, Xian (China)); Jay, Gao (School of Geography, Geology and Environmental Science, Univ. of Auckland, Auckland (New Zealand))

    2011-11-15

    Determination of surface reflectance in the red and blue channels is a critical step in retrieving aerosol optical thickness (AOT) from Moderate Resolution Imaging Spectroradiometer (MODIS) measurements. The MODIS Collection 005 (C005) aerosol algorithm uses a ratio method to determine the surface reflectance in the red (0.66 mum) and blue (0.47 mum) channels from the surface reflectance in the 2.1 mum channel using global surface reflectance relationships. In this study, we attempted to improve the retrieval of AOT from MODIS measurements using a new surface parameterization derived using ground-based sunphotometer data and 6S radiative transfer code. The estimated surface reflectance in the red, blue and near-IR channel were used to derive ratio between them for use in the new retrieval from MODIS data. Our results demonstrate that the ratio of surface reflectance in the red and blue channels to the surface reflectance in the 2.1 mum channel varies seasonally in the Xianlin district of Nanjing City, China. These ratios are different from those assumed by the MODIS aerosol algorithm for the retrieval of AOT over land. The use of the appropriate ratio for the study area in a given season significantly improves the accuracy with the absolute error decreased from 0.15 to 0.08 and the relative error reduced from 31% to 17% in retrieving AOT from MODIS data

  12. Remote Sensing Reflectance at 667 nm, Terra MODIS, NPP, 0.05 degrees, Global, Science Quality

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — MODIS measures the remote sensing reflectance (Rrs) at 667nm. This can be used to view very high concentrations of phytoplankton in the very surface of the water.

  13. Downscaling MODIS Surface Reflectance to Improve Water Body Extraction

    OpenAIRE

    Xianghong Che; Min Feng; Hao Jiang; Jia Song; Bei Jia

    2015-01-01

    Inland surface water is essential to terrestrial ecosystems and human civilization. Accurate mapping of surface water dynamic is vital for both scientific research and policy-driven applications. MODIS provides twice observation per day, making it perfect for monitoring temporal water dynamic. Although MODIS provides two bands at 250 m resolution, accurately deriving water area always depends on observations from the spectral bands with 500 m resolution, which limits its discrimination abilit...

  14. An Algorithm for the Retrieval of 30-m Snow-Free Albedo from Landsat Surface Reflectance and MODIS BRDF

    Science.gov (United States)

    Shuai, Yanmin; Masek, Jeffrey G.; Gao, Feng; Schaaf, Crystal B.

    2011-01-01

    We present a new methodology to generate 30-m resolution land surface albedo using Landsat surface reflectance and anisotropy information from concurrent MODIS 500-m observations. Albedo information at fine spatial resolution is particularly useful for quantifying climate impacts associated with land use change and ecosystem disturbance. The derived white-sky and black-sky spectral albedos maybe used to estimate actual spectral albedos by taking into account the proportion of direct and diffuse solar radiation arriving at the ground. A further spectral-to-broadband conversion based on extensive radiative transfer simulations is applied to produce the broadband albedos at visible, near infrared, and shortwave regimes. The accuracy of this approach has been evaluated using 270 Landsat scenes covering six field stations supported by the SURFace RADiation Budget Network (SURFRAD) and Atmospheric Radiation Measurement Southern Great Plains (ARM/SGP) network. Comparison with field measurements shows that Landsat 30-m snow-free shortwave albedos from all seasons generally achieve an absolute accuracy of +/-0.02 - 0.05 for these validation sites during available clear days in 2003-2005,with a root mean square error less than 0.03 and a bias less than 0.02. This level of accuracy has been regarded as sufficient for driving global and regional climate models. The Landsat-based retrievals have also been compared to the operational 16-day MODIS albedo produced every 8-days from MODIS on Terra and Aqua (MCD43A). The Landsat albedo provides more detailed landscape texture, and achieves better agreement (correlation and dynamic range) with in-situ data at the validation stations, particularly when the stations include a heterogeneous mix of surface covers.

  15. Improved retrieval of aerosol optical thickness from MODIS measurements through derived surface reflectance over Nanjing, China

    OpenAIRE

    Zha, Yong; Wang, Qiao; Yuan, Jie; Gao, Jay; Jiang, Jianjun; Lu, Heng; Huang, Jiazhu

    2011-01-01

    Determination of surface reflectance in the red and blue channels is a critical step in retrieving aerosol optical thickness (AOT) from Moderate Resolution Imaging Spectroradiometer (MODIS) measurements. The MODIS Collection 005 (C005) aerosol algorithm uses a ratio method to determine the surface reflectance in the red (0.66 μm) and blue (0.47 μm) channels from the surface reflectance in the 2.1 μm channel using global surface reflectance relationships. In this study, we attempted to improve...

  16. Inter-annual variability of aerosol optical depth over the tropical Atlantic Ocean based on MODIS-Aqua observations over the period 2002-2012

    Science.gov (United States)

    Gkikas, Antonis; Hatzianastassiou, Nikolaos

    2013-04-01

    The tropical Atlantic Ocean is affected by dust and biomass burning aerosol loads transported from the western parts of the Saharan desert and the sub-Sahel regions, respectively. The spatial and temporal patterns of this transport are determined by the aerosol emission rates, their deposition (wet and dry), by the latitudinal shift of the Intertropical Convergence Zone (ITCZ) and the prevailing wind fields. More specifically, in summer, Saharan dust aerosols are transported towards the Atlantic Ocean, even reaching the Gulf of Mexico, while in winter the Atlantic Ocean transport takes place in more southern latitudes, near the equator, sometimes reaching the northern parts of South America. In the later case, dust is mixed with biomass burning aerosols originating from agricultural activities in the sub-Sahel, associated with prevailing north-easterly airflow (Harmattan winds). Satellite observations are the appropriate tool for describing this African aerosol export, which is important to atmospheric, oceanic and climate processes, offering the advantage of complete spatial coverage. In the present study, we use satellite measurements of aerosol optical depth at 550nm (AOD550nm), on a daily and monthly basis, derived from MODIS-Aqua platform, at 1ox1o spatial resolution (Level 3), for the period 2002-2012. The primary objective is to determine the pixel-level and regional mean anomalies of AOD550nm over the entire study period. The regime of the anomalies of African export is interpreted in relation to the aerosol source areas, precipitation, wind patterns and temporal variability of the North Atlantic Oscillation Index (NAOI). In order to ensure availability of AOD over the Sahara desert, MODIS-Aqua Deep Blue products are also used. As for precipitation, Global Precipitation Climatology Project (GPCP) data at 2.5ox2.5o are used. The wind fields are taken from the National Center for Environmental Prediction (NCEP). Apart from the regime of African aerosol export

  17. Compositing MODIS Terra and Aqua 250m daily surface reflectance data sets for vegetation monitoring

    Science.gov (United States)

    Remote sensing based vegetation Indices have been proven valuable in providing a spatially complete view of crop’s vegetation condition, which also manifests the impact of the disastrous events such as massive flood and drought. VegScape, a web GIS application for crop vegetation condition monitorin...

  18. Long-term trend of aerosol optical depth derived from MODIS Aqua using linear regression and ensemble empirical mode decomposition over East Asia

    Science.gov (United States)

    KIM, J.

    2015-12-01

    Aerosol has played an important role in air quality for short term and climate change for long term. Especially, it is important to understand how aerosol optical depth (AOD) has changed to date for the prognosis of future atmospheric state and radiation budget which are related to human life. In this study, the trend of AOD at 550 nm from MODIS Aqua (MYD08) was estimated for 10 years from 2004 to 2014 using linear regression method and ensemble empirical mode decomposition method (EEMD). Search region was selected to East Asia [18.5°N-51.5°N, 85.5°E-150.5°E] which is considered to be of great interest in emission source. The result of linear regression shows remarkably increasing trend in North and East China including Sanjiang, Hailun, Beijing, Beijing forest and Jinozhou Bay, than rather downward trend in other neighboring regions. Actually, however, AOD has seasonality itself and its trend is also affected by external source consistently, so non-linear trend analysis was conducted to analyze the changing tendency of AOD trends. Consequently, secular trends of AOD defined by EEMD showed almost similar values over the entire region, but their shapes over time are quite different with those of linear regression. Here, AOD linear trend in Beijing has monotonically increased [0.03% yr-1] since 2004, but its non-linear trend shows that initial increasing trend has alleviated and even turned into downward trend from about 2010. Lastly, the validation of MODIS AOD with AErosol RObotic NETwork (AERONET) was conducted additionally which showed fairly good agreement with those of AERONET (R=0.901, RMSE=0.226, MAE=0.031, MBE=-0.001).

  19. Multitemporal Cross-Calibration of the Terra MODIS and Landsat 7 ETM+ Reflective Solar Bands

    Science.gov (United States)

    Angal, Amit; Xiong, Xiaoxiong; Wu, Aisheng; Changler, Gyanesh; Choi, Taeyoyung

    2013-01-01

    In recent years, there has been a significant increase in the use of remotely sensed data to address global issues. With the open data policy, the data from the Moderate Resolution Imaging Spectroradiometer (MODIS) and Enhanced Thematic Mapper Plus (ETM+) sensors have become a critical component of numerous applications. These two sensors have been operational for more than a decade, providing a rich archive of multispectral imagery for analysis of mutitemporal remote sensing data. This paper focuses on evaluating the radiometric calibration agreement between MODIS and ETM+ using the near-simultaneous and cloud-free image pairs over an African pseudo-invariant calibration site, Libya 4. To account for the combined uncertainties in the top-of-atmosphere (TOA) reflectance due to surface and atmospheric bidirectional reflectance distribution function (BRDF), a semiempirical BRDF model was adopted to normalize the TOA reflectance to the same illumination and viewing geometry. In addition, the spectra from the Earth Observing-1 (EO-1) Hyperion were used to compute spectral corrections between the corresponding MODIS and ETM+ spectral bands. As EO-1 Hyperion scenes were not available for all MODIS and ETM+ data pairs, MODerate resolution atmospheric TRANsmission (MODTRAN) 5.0 simulations were also used to adjust for differences due to the presence or lack of absorption features in some of the bands. A MODIS split-window algorithm provides the atmospheric water vapor column abundance during the overpasses for the MODTRAN simulations. Additionally, the column atmospheric water vapor content during the overpass was retrieved using the MODIS precipitable water vapor product. After performing these adjustments, the radiometric cross-calibration of the two sensors was consistent to within 7%. Some drifts in the response of the bands are evident, with MODIS band 3 being the largest of about 6% over 10 years, a change that will be corrected in Collection 6 MODIS processing.

  20. Evaluation of Aqua MODIS Collection 6 AOD Parameters for Air Quality Research over the Continental United States

    Directory of Open Access Journals (Sweden)

    J. H. Belle

    2016-10-01

    Full Text Available Satellite-retrieved aerosol optical depth (AOD has become an important predictor of ground-level particulate matter (PM and greatly empowered air pollution research worldwide. We evaluated the AOD parameters included in the Collection 6 aerosol product of the Moderate Resolution Imaging Spectroradiometer (MODIS for two key factors affecting their applications in air quality research—coverage and accuracy—over the continental US. For the high confidence retrievals (QAC 3, the 10 km DB-DT combined AOD has the best coverage nationwide (29.7% of the days in a year in any given 12 km grid cell. While the Eastern US generally had more successful AOD retrievals, the highest spatial coverage of AOD parameters were found in California (>55% and other vegetated parts of the Western US. If lower QAC retrievals were included, the coverage of the 10 km DB AOD was dramatically increased to 49.6%. In the Eastern US, the QAC 3 retrievals of all four AOD parameters are highly correlated with AERONET observations (correlation coefficients between 0.80 and 0.92. In the Western US, positive retrieval errors existed in all MODIS AOD parameters, resulting in lower correlations with AERONET. AOD retrieval errors showed significant dependence on flight geometry, land cover type, and weather conditions. To ensure appropriate use of these AOD values, air quality researchers should carefully balance the needs for coverage and accuracy, and develop additional data screening criteria based on their study design.

  1. Assessment of biases in MODIS surface reflectance due to Lambertian approximation

    Energy Technology Data Exchange (ETDEWEB)

    Cook, Robert B [ORNL; SanthanaVannan, Suresh K [ORNL

    2010-08-01

    Using MODIS data and the AERONET-based Surface Reflectance Validation Network (ASRVN), this work studies errors of MODIS atmospheric correction caused by the Lambertian approximation. On one hand, this approximation greatly simplifies the radiative transfer model, reduces the size of the look-up tables, and makes operational algorithm faster. On the other hand, uncompensated atmospheric scattering caused by Lambertian model systematically biases the results. For example, for a typical bowl-shaped bidirectional reflectance distribution function (BRDF), the derived reflectance is underestimated at high solar or view zenith angles, where BRDF is high, and is overestimated at low zenith angles where BRDF is low. The magnitude of biases grows with the amount of scattering in the atmosphere, i.e., at shorter wavelengths and at higher aerosol concentration. The slope of regression of Lambertian surface reflectance vs. ASRVN bidirectional reflectance factor (BRF) is about 0.85 in the red and 0.6 in the green bands. This error propagates into the MODIS BRDF/albedo algorithm, slightly reducing the magnitude of overall reflectance and anisotropy of BRDF. This results in a small negative bias of spectral surface albedo. An assessment for the GSFC (Greenbelt, USA) validation site shows the albedo reduction by 0.004 in the near infrared, 0.005 in the red, and 0.008 in the green MODIS bands.

  2. Biomass Burning Aerosol Absorption Measurements with MODIS Using the Critical Reflectance Method

    Science.gov (United States)

    Zhu, Li; Martins, Vanderlei J.; Remer, Lorraine A.

    2010-01-01

    This research uses the critical reflectance technique, a space-based remote sensing method, to measure the spatial distribution of aerosol absorption properties over land. Choosing two regions dominated by biomass burning aerosols, a series of sensitivity studies were undertaken to analyze the potential limitations of this method for the type of aerosol to be encountered in the selected study areas, and to show that the retrieved results are relatively insensitive to uncertainties in the assumptions used in the retrieval of smoke aerosol. The critical reflectance technique is then applied to Moderate Resolution Imaging Spectrometer (MODIS) data to retrieve the spectral aerosol single scattering albedo (SSA) in South African and South American 35 biomass burning events. The retrieved results were validated with collocated Aerosol Robotic Network (AERONET) retrievals. One standard deviation of mean MODIS retrievals match AERONET products to within 0.03, the magnitude of the AERONET uncertainty. The overlap of the two retrievals increases to 88%, allowing for measurement variance in the MODIS retrievals as well. The ensemble average of MODIS-derived SSA for the Amazon forest station is 0.92 at 670 nm, and 0.84-0.89 for the southern African savanna stations. The critical reflectance technique allows evaluation of the spatial variability of SSA, and shows that SSA in South America exhibits higher spatial variation than in South Africa. The accuracy of the retrieved aerosol SSA from MODIS data indicates that this product can help to better understand 44 how aerosols affect the regional and global climate.

  3. The Collection 6 MODIS aerosol products over land and ocean

    OpenAIRE

    R. C. Levy; Mattoo, S; L. A. Munchak; Remer, L. A.; A. M. Sayer; F. Patadia; Hsu, N. C.

    2013-01-01

    The twin Moderate resolution Imaging Spectroradiometer (MODIS) sensors have been flying on Terra since 2000 and Aqua since 2002, creating an extensive data set of global Earth observations. Here, we introduce the Collection 6 (C6) algorithm to retrieve aerosol optical depth (AOD) and aerosol size parameters from MODIS-observed spectral reflectance. While not a major overhaul from the previous Collection 5 (C5) version, there are enough changes that there are significant impa...

  4. The Collection 6 MODIS aerosol products over land and ocean

    OpenAIRE

    R. C. Levy; Mattoo, S; L. A. Munchak; Remer, L. A.; A. M. Sayer; Hsu, N. C.

    2013-01-01

    The twin Moderate Imaging resolution Spectroradiometer (MODIS) sensors have been flying on Terra since 2000 and Aqua since 2002, creating an incredible dataset of global Earth observations. Here, we introduce the Collection 6 (C6) algorithm to retrieve aerosol optical depth (AOD) and aerosol size parameters from MODIS-observed spectral reflectance. While not a major overhaul from the previous Collection 5 (C5) version, there are enough changes that there is significant impact on the products ...

  5. Variation of MODIS reflectance and vegetation indices with viewing geometry and soybean development.

    Science.gov (United States)

    Breunig, Fábio M; Galvão, Lênio S; Formaggio, Antônio R; Epiphanio, José C N

    2012-06-01

    Directional effects introduce a variability in reflectance and vegetation index determination, especially when large field-of-view sensors are used (e.g., Moderate Resolution Imaging Spectroradiometer - MODIS). In this study, we evaluated directional effects on MODIS reflectance and four vegetation indices (Normalized Difference Vegetation Index - NDVI; Enhanced Vegetation Index - EVI; Normalized Difference Water Index - NDWI(1640) and NDWI(2120)) with the soybean development in two growing seasons (2004-2005 and 2005-2006). To keep the reproductive stage for a given cultivar as a constant factor while varying viewing geometry, pairs of images obtained in close dates and opposite view angles were analyzed. By using a non-parametric statistics with bootstrapping and by normalizing these indices for angular differences among viewing directions, their sensitivities to directional effects were studied. Results showed that the variation in MODIS reflectance between consecutive phenological stages was generally smaller than that resultant from viewing geometry for closed canopies. The contrary was observed for incomplete canopies. The reflectance of the first seven MODIS bands was higher in the backscattering. Except for the EVI, the other vegetation indices had larger values in the forward scattering direction. Directional effects decreased with canopy closure. The NDVI was lesser affected by directional effects than the other indices, presenting the smallest differences between viewing directions for fixed phenological stages. PMID:22473302

  6. MODIS Instrument Operation and Calibration Improvements

    Science.gov (United States)

    Xiong, X.; Angal, A.; Madhavan, S.; Link, D.; Geng, X.; Wenny, B.; Wu, A.; Chen, H.; Salomonson, V.

    2014-01-01

    Terra and Aqua MODIS have successfully operated for over 14 and 12 years since their respective launches in 1999 and 2002. The MODIS on-orbit calibration is performed using a set of on-board calibrators, which include a solar diffuser for calibrating the reflective solar bands (RSB) and a blackbody for the thermal emissive bands (TEB). On-orbit changes in the sensor responses as well as key performance parameters are monitored using the measurements of these on-board calibrators. This paper provides an overview of MODIS on-orbit operation and calibration activities, and instrument long-term performance. It presents a brief summary of the calibration enhancements made in the latest MODIS data collection 6 (C6). Future improvements in the MODIS calibration and their potential applications to the S-NPP VIIRS are also discussed.

  7. Detection of frequently-burn locations using multi-temporal Terra/Aqua MODIS fire product (MOD14) in Oudomxay province, Laos

    International Nuclear Information System (INIS)

    Wildfire is natural and man-made disaster that relates to global warming and climate change. Wildfire is prominent disaster that destroys natural resources, and causes enormous danger to human life and property. The study on the spatial and temporal distribution of wildfire is significant to understand wildfire occurrence and behavior. In the past, people usually study on the pattern of wildfire and open-space burning according to the daily number of active fire detected by MODIS sensor onboard of Terra and Aqua satellites for a particular area at the time of satellite over pass. However, there is no study that focused on the active fire that frequently occurred at the same location for a given period of time. Therefore, in this paper, the authors has focused on the study of frequently-burn locations in Oudomxay province of Laos, which has the 3rd highest active fire number in burning season of year 2007-2009 using spatial and statistical analysis of the active fire distribution and occurrence by time and space. The results of the study show that the highest number of burning frequency is 6 and 7 times within the study period and these numbers are located at 3 districts. One is Xai district which has the highest frequently-burn location for 7 times during the study period at the coordinate of N20.72° and E101.88°. The second districts are Beng and Nga districts which has the 2nd highest frequently-burn location for 6 times during the study period at the coordinate of N 20.28°, E101.68°, and N20.17°, E102.02°, respectively. The obtained information on frequently-burn locations in the province would be useful to identify the repeat burning activity by the local people occurred in the same location and allows the forestry and agricultural officers understand the wildfire distribution pattern

  8. MODIS/TERRA MOD09Q1 Surface Reflectance 8-Day L3 Global 250m Version 6

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The MODIS Surface Reflectance products provide an estimate of the surface spectral reflectance as it would be measured at ground level in the absence of atmospheric...

  9. MODIS/TERRA MOD09CMG Surface Reflectance Daily L3 Global 0.05Deg CMG

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The MODIS Surface Reflectance products provide an estimate of the surface spectral reflectance as it would be measured at ground level in the absence of atmospheric...

  10. MODIS/TERRA MOD09A1 Surface Reflectance 8-Day L3 Global 500m Version 6

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The MODIS Surface Reflectance products provide an estimate of the surface spectral reflectance as it would be measured at ground level in the absence of atmospheric...

  11. MODIS/TERRA MOD09GA Surface Reflectance Daily L2G Global 1km and 500m Version 6

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The MODIS Surface Reflectance products provide an estimate of the surface spectral reflectance as it would be measured at ground level in the absence of atmospheric...

  12. MODIS/TERRA MOD09GQ Surface Reflectance Daily L2G Global 250m Version 6

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The MODIS Surface Reflectance products provide an estimate of the surface spectral reflectance as it would be measured at ground level in the absence of atmospheric...

  13. MODIS/TERRA MOD09CMG Surface Reflectance Daily L3 Global 0.05Deg CMG Version 6

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The MODIS Surface Reflectance products provide an estimate of the surface spectral reflectance as it would be measured at ground level in the absence of atmospheric...

  14. MODIS/TERRA MOD09GA Surface Reflectance Daily L2G Global 1km and 500m

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The MODIS Surface Reflectance products provide an estimate of the surface spectral reflectance as it would be measured at ground level in the absence of atmospheric...

  15. Comparison of chlorophyll products derived from MODIS-Aqua and modification of operational algorithms in the South China Sea%南海海域MODIS-Aqua叶绿素浓度产品的精度对比和区域性算法修正

    Institute of Scientific and Technical Information of China (English)

    赵文静; 曹文熙; 王桂芬; 胡水波; 林俊芳; 许占堂

    2014-01-01

    利用2004~2012年在南海获得的9个航次的实测Chl-a数据,采用NASA标准业务化算法OC3和针对低Chl-a水体所发展的最新算法OCI反演获得了相应的MODIS-Aqua Chl-a产品.通过建立实测与遥感产品的时空匹配数据对,开展了Chl-a产品的适用性评估,并对比分析了上述两种算法的性能.在此基础上,利用南海实测遥感反射率(Rrs(λ))和MODIS-AquaRrs(λ)产品以及相应实测Chl-a的匹配数据集,分别对算法OC3和OCI进行了区域性修正.结果显示:基于算法OC3和OCI反演所得的MODIS-Aqua Chl-a产品值均高估了实测值,平均绝对误差(APD)的精度分别为56.30%和42.58%,且算法OCI可明显改善低Chl-a水体(<0.25 mg· m-3)的反演精度;采用南海MODIS-AquaRrs(λ)产品与实测Chl-a匹配数据集(N=82)修正后的区域性算法NOC3和NOCI的精度均有不同程度提高,APD精度分别为37.85%和36.74%;采用现场实测Rrs(λ)与Chl-a匹配数据集(N=123)进行区域性修正后的算法INOC3和INOCI的APD精度分别为36.61%和37.79%,上述两种方案精度较为接近.因此,对于南海海域而言,算法的区域性修正对于改善MODIS-Aqua Chl-a产品精度非常重要.

  16. 基于遗传算法综合Terra/Aqua MODIS热红外数据反演地表组分温度%Genetic algorithm based surface component temperatures retrieval by integrating MODIS TIR DATA from Terra and Aqua satellites

    Institute of Scientific and Technical Information of China (English)

    孙珂; 陈圣波

    2012-01-01

    混合像元组分温度相对来说更有应用价值,而多角度热红外遥感的发展推动了混合像元组分温度反演基础和方法的发展.根据前期数值模拟得到Terra和Aqua卫星上的MODIS测量可以认为是同一卫星在两个不同观测时间和观测角度上的测量,综合利用Terra和Aqua卫星上的MODIS数据反演混合像元内土壤和植被组分温度.根据混合像元热红外辐射模型,利用遗传算法,分别模拟Terra卫星MODIS的32和33通道,以及Terra和Aqua卫星上MODIS的32通道辐射反演了河北怀来试验区范围内植被覆盖率、土壤组分温度和比辐射率、植被组分温度和比辐射率等表面参数.通过与实测数据进行比较,综合利用上午Terra和下午Aqua卫星32通道数据反演的上午植被组分温度与地面同步测量温度偏差在1℃内,而利用上午Terra卫星32和33通道数据反演的上午植被组分温度与地面同步测量值偏差在1.4℃内.尽管利用双星数据反演的组分温度精度相对较高,但针对同一个像元,两个方案反演的结果有一定偏差.%The component temperatures are key parameters in the environment problems. The multi-angle thermal infrared data are important for the retrieval of component temperature. MODIS (Moderate Resolution Imaging Spectroradiom-eter) is one of the sensors onboard EOS-Terra and EOS-Aqua, two sun-synchronous polar orbiting satellites. The sensitivity analysis shows that the same MODIS bands of Terra and Aqua satellites measures in the same behavior under the same variations of atmospheric water vapor, solar and viewing geometries. These MODIS bands may be considered to be the observations of a satellite at two viewing angles and two viewing times. In the study, the foliage and soil component temperature were retrieved by integrating these MODIS data. Based on linear thermal infrared radiation model, the bands 32 and 33 in Terra-MODIS, or the band 32 in Tcrra-MODIS and Aqua-MODIS

  17. MODIS Directional Surface Reflectance Product: Method, Error Estimates and Validation

    Science.gov (United States)

    Vermote, Eric; Kotchenova, Svetlana

    The surface bidirectional reflectance factor (BRF) is the ratio between reflected radiance measured in specific observation geometry (zenith and azimuth) within an infinitely small solid angle and irradiance incident on the surface from a direct source of illumination (zenith and azimuth). The BRF is determined from satellite observations through an atmospheric correction (AC) process. When properly retrieved, the surface BRF is fully decoupled from an atmospheric signal, and thus represents the value as measured by an ideal sensor held at the same view geometry and located just above the Earth's surface assuming an absence of atmosphere.

  18. Linking glacier annual mass balance and glacier albedo retrieved from MODIS data

    OpenAIRE

    Dumont, M; Gardelle, J.; P. Sirguey; A. Guillot; Six, D.; Rabatel, A.; Y. Arnaud

    2012-01-01

    Albedo is one of the variables controlling the mass balance of temperate glaciers. Multispectral imagers, such as MODerate Imaging Spectroradiometer (MODIS) on board the TERRA and AQUA satellites, provide a means to monitor glacier surface albedo. In this study, different methods to retrieve broadband glacier surface albedo from MODIS data are compared. The effect of multiple reflections due to the rugged topography and of the anisotropic reflection of snow and ...

  19. Daily MODIS 500 m Reflectance Anisotropy Direct Broadcast (DB) Products for Monitoring Vegetation Phenology Dynamics

    Science.gov (United States)

    Shuai, Yanmin; Schaaf, Crystal; Zhang, Xiaoyang; Strahler, Alan; Roy, David; Morisette, Jeffrey; Wang, Zhuosen; Nightingale, Joanne; Nickeson, Jaime; Richardson, Andrew D.; Xie, Donghui; Wang, Jindi; Li, Xiaowen; Strabala, Kathleen; Davies, James E.

    2013-01-01

    Land surface vegetation phenology is an efficient bio-indicator for monitoring ecosystem variation in response to changes in climatic factors. The primary objective of the current article is to examine the utility of the daily MODIS 500 m reflectance anisotropy direct broadcast (DB) product for monitoring the evolution of vegetation phenological trends over selected crop, orchard, and forest regions. Although numerous model-fitted satellite data have been widely used to assess the spatio-temporal distribution of land surface phenological patterns to understand phenological process and phenomena, current efforts to investigate the details of phenological trends, especially for natural phenological variations that occur on short time scales, are less well served by remote sensing challenges and lack of anisotropy correction in satellite data sources. The daily MODIS 500 m reflectance anisotropy product is employed to retrieve daily vegetation indices (VI) of a 1 year period for an almond orchard in California and for a winter wheat field in northeast China, as well as a 2 year period for a deciduous forest region in New Hampshire, USA. Compared with the ground records from these regions, the VI trajectories derived from the cloud-free and atmospherically corrected MODIS Nadir BRDF (bidirectional reflectance distribution function) adjusted reflectance (NBAR) capture not only the detailed footprint and principal attributes of the phenological events (such as flowering and blooming) but also the substantial inter-annual variability. This study demonstrates the utility of the daily 500 m MODIS reflectance anisotropy DB product to provide daily VI for monitoring and detecting changes of the natural vegetation phenology as exemplified by study regions comprising winter wheat, almond trees, and deciduous forest.

  20. The impact of horizontal heterogeneities, cloud fraction, and liquid water path on warm cloud effective radii from CERES-like Aqua MODIS retrievals

    Directory of Open Access Journals (Sweden)

    D. Painemal

    2013-10-01

    Full Text Available The impact of horizontal heterogeneities, liquid water path (LWP from AMSR-E, and cloud fraction (CF on MODIS cloud effective radius (re, retrieved from the 2.1 μm (re2.1 and 3.8 μm (re3.8 channels, is investigated for warm clouds over the southeast Pacific. Values of re retrieved using the CERES algorithms are averaged at the CERES footprint resolution (∼20 km, while heterogeneities (Hσ are calculated as the ratio between the standard deviation and mean 0.64 μm reflectance. The value of re2.1 strongly depends on CF, with magnitudes up to 5 μm larger than those for overcast scenes, whereas re3.8 remains insensitive to CF. For cloudy scenes, both re2.1 and re3.8 increase with Hσ for any given AMSR-E LWP, but re2.1 changes more than for re3.8. Additionally, re3.8–re2.1 differences are positive (Hσ 45 gm−2, and negative (up to −4 μm for larger Hσ. While re3.8–re2.1 differences in homogeneous scenes are qualitatively consistent with in situ microphysical observations over the region of study, negative differences – particularly evinced in mean regional maps – are more likely to reflect the dominant bias associated with cloud heterogeneities rather than information about the cloud vertical structure. The consequences for MODIS LWP are also discussed.

  1. Variation of MODIS reflectance and vegetation indices with viewing geometry and soybean development

    Directory of Open Access Journals (Sweden)

    Fábio M. Breunig

    2012-06-01

    Full Text Available Directional effects introduce a variability in reflectance and vegetation index determination, especially when large field-of-view sensors are used (e.g., Moderate Resolution Imaging Spectroradiometer - MODIS. In this study, we evaluated directional effects on MODIS reflectance and four vegetation indices (Normalized Difference Vegetation Index - NDVI; Enhanced Vegetation Index - EVI; Normalized Difference Water Index - NDWI1640 and NDWI2120 with the soybean development in two growing seasons (2004-2005 and 2005-2006. To keep the reproductive stage for a given cultivar as a constant factor while varying viewing geometry, pairs of images obtained in close dates and opposite view angles were analyzed. By using a non-parametric statistics with bootstrapping and by normalizing these indices for angular differences among viewing directions, their sensitivities to directional effects were studied. Results showed that the variation in MODIS reflectance between consecutive phenological stages was generally smaller than that resultant from viewing geometry for closed canopies. The contrary was observed for incomplete canopies. The reflectance of the first seven MODIS bands was higher in the backscattering. Except for the EVI, the other vegetation indices had larger values in the forward scattering direction. Directional effects decreased with canopy closure. The NDVI was lesser affected by directional effects than the other indices, presenting the smallest differences between viewing directions for fixed phenological stages.Efeitos direcionais introduzem variabilidade na reflectância e na determinação de índices de vegetação, especialmente quando sensores de amplo campo de visada são usados (p.ex., Moderate Resolution Imaging Spectroradiometer - MODIS. Neste estudo, nós avaliamos os efeitos direcionais sobre a reflectância e quatro índices de vegetação (Normalized Difference Vegetation Index - NDVI; Enhanced Vegetation Index - EVI; Normalized

  2. Análise da dinâmica sazonal e separabilidade espectral de algumas fitofisionomias do cerrado com índices de vegetação dos sensores MODIS/TERRA e AQUA Analysis of the seasonal dynamics and spectral separability of some savanna physiognomies with vegetation indices derived from MODIS/TERRA AND AQUA

    Directory of Open Access Journals (Sweden)

    Veraldo Liesenberg

    2007-04-01

    Full Text Available Composições de 16 dias de índices de vegetação do sensor MODerate resolution Imaging Spectroradiometer (MODIS, com resolução espacial de 1km, a bordo dos satélites TERRA e AQUA, foram usadas para caracterizar a dinâmica sazonal em 2004 de cinco fitofisionomias de Cerrado e analisar a sua separabilidade espectral. Os índices Normalized Difference Vegetation Index (NDVI e Enhanced Vegetation Index (EVI, calculados a partir dos dados dos sensores de ambas as plataformas e de uma base comum de pixels, foram comparados entre si. Os resultados indicaram que: (a dentre as fitofisionomias estudadas, a Floresta Estacional decídua apresentou uma dinâmica sazonal muito marcante em função da perda de folhas da estação chuvosa para a seca (substancial redução nos índices e do rápido verdejamento com o início da precipitação no final de outubro (rápido incremento de NDVI e EVI; (b o NDVI mostrou maior variabilidade entre as classes de vegetação do que o EVI apenas na estação seca; (c a discriminação entre as fitofisionomias melhorou da estação chuvosa para a seca; (d o NDVI foi mais eficiente do que o EVI para discriminar as classes de vegetação na estação seca, ocorrendo o contrário na estação chuvosa; e (e na maioria das datas selecionadas para estudo, não houve diferenças estatisticamente significativas entre os índices de vegetação gerados de ambas as plataformas, apesar das variações na qualidade dos pixels selecionados para as composições de 16 dias e na geometria de iluminação e de visada.MODerate-resolution Imaging Spectroradiometer (MODIS 16-day vegetation index composites with 1 km of spatial resolution from TERRA and AQUA satellites were used to characterize the seasonal dynamics of five Brazilian savanna physiognomies and to analyze their spectral separability in 2004. The Normalized Difference Vegetation Index (NDVI and Enhanced Vegetation Index (EVI, using data from both platforms and from a

  3. Application-Ready Expedited MODIS Data for Operational Land Surface Monitoring of Vegetation Condition

    Directory of Open Access Journals (Sweden)

    Jesslyn F. Brown

    2015-12-01

    Full Text Available Monitoring systems benefit from high temporal frequency image data collected from the Moderate Resolution Imaging Spectroradiometer (MODIS system. Because of near-daily global coverage, MODIS data are beneficial to applications that require timely information about vegetation condition related to drought, flooding, or fire danger. Rapid satellite data streams in operational applications have clear benefits for monitoring vegetation, especially when information can be delivered as fast as changing surface conditions. An “expedited” processing system called “eMODIS” operated by the U.S. Geological Survey provides rapid MODIS surface reflectance data to operational applications in less than 24 h offering tailored, consistently-processed information products that complement standard MODIS products. We assessed eMODIS quality and consistency by comparing to standard MODIS data. Only land data with known high quality were analyzed in a central U.S. study area. When compared to standard MODIS (MOD/MYD09Q1, the eMODIS Normalized Difference Vegetation Index (NDVI maintained a strong, significant relationship to standard MODIS NDVI, whether from morning (Terra or afternoon (Aqua orbits. The Aqua eMODIS data were more prone to noise than the Terra data, likely due to differences in the internal cloud mask used in MOD/MYD09Q1 or compositing rules. Post-processing temporal smoothing decreased noise in eMODIS data.

  4. EROS MODIS Normalized Difference Vegetation Index: 2001-Present

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — eMODIS processes calibrated radiance data (level-1B) acquired by the MODIS sensors on the EOS Terra and Aqua satellites by combining MODIS Land Science Collection 5...

  5. eMODIS: A User-Friendly Data Source

    Science.gov (United States)

    Jenkerson, Calli; Maiersperger, Thomas; Schmidt, Gail

    2010-01-01

    The U.S. Geological Survey's (USGS) Earth Resources Observation and Science (EROS) Center is generating a suite of products called 'eMODIS' based on Moderate Resolution Imaging Spectroradiometer (MODIS) data acquired by the National Aeronautics and Space Administration's (NASA) Earth Observing System (EOS). With a more frequent repeat cycle than Landsat and higher spatial resolutions than the Advanced Very High Resolution Spectroradiometer (AVHRR), MODIS is well suited for vegetation studies. For operational monitoring, however, the benefits of MODIS are counteracted by usability issues with the standard map projection, file format, composite interval, high-latitude 'bow-tie' effects, and production latency. eMODIS responds to a community-specific need for alternatively packaged MODIS data, addressing each of these factors for real-time monitoring and historical trend analysis. eMODIS processes calibrated radiance data (level-1B) acquired by the MODIS sensors on the EOS Terra and Aqua satellites by combining MODIS Land Science Collection 5 Atmospherically Corrected Surface Reflectance production code and USGS EROS MODIS Direct Broadcast System (DBS) software to create surface reflectance and Normalized Difference Vegetation Index (NDVI) products. eMODIS is produced over the continental United States and over Alaska extending into Canada to cover the Yukon River Basin. The 250-meter (m), 500-m, and 1,000-m products are delivered in Geostationary Earth Orbit Tagged Image File Format (Geo- TIFF) and composited in 7-day intervals. eMODIS composites are projected to non-Sinusoidal mapping grids that best suit the geography in their areas of application (see eMODIS Product Description below). For eMODIS products generated over the continental United States (eMODIS CONUS), the Terra (from 2000) and Aqua (from 2002) records are available and continue through present time. eMODIS CONUS also is generated in an expedited process that delivers a 7-day rolling composite

  6. Status of MODIS Instruments and Future Calibration Improvements

    Science.gov (United States)

    Xiong, X.; Angal, A.; Wu, A.; Salomonson, V. V.

    2015-12-01

    MODIS is one of the key instruments currently operated on two major missions for the NASA's Earth Observing System (EOS) program: Terra and Aqua launched in 1999 and 2002, respectively. Nearly 40 data products have been routinely generated from both Terra and Aqua MODIS observations and widely distributed to the science community and users worldwide for their studies of the earth's system and changes in its geophysical properties. To date, each MODIS instrument operation remains nominal and its on-board calibrators (OBC) continue to function satisfactorily. On a regular basis, MODIS reflective solar bands (RSB) calibration is performed by a solar diffuser (SD) and a solar diffuser stability monitor (SDSM). For the thermal emissive bands (TEB), an on-board blackbody (BB) provides a scan-by-scan calibration reference. Since launch, extensive calibration and characterization activities have been scheduled and implemented by the MODIS Characterization Support Team (MCST) to produce and update calibration look-up tables (LUT). This presentation provides an overview of both Terra and Aqua MODIS instrument status, their on-orbit operation and calibration activities, and radiometric, spectral, and spatial performance. It describes calibration changes (algorithms and look-up tables) made for the MODIS Level 1B (L1B) data collection 6 (C6) and discusses remaining challenging issues and ongoing effort for future improvements. As expected, lessons from both Terra and Aqua MODIS have benefitted and will continue to help the S-NPP and JPSS VIIRS instruments in terms of on-orbit operation strategies and calibration enhancements.

  7. On the assimilation of MODIS reflectance into a detailed snowpack model

    Science.gov (United States)

    Charrois, Luc; Dumont, Marie; Cosme, Emmanuel; Lafaysse, Matthieu; Morin, Samuel; Libois, Quentin; Picard, Ghislain

    2016-04-01

    One of the major sources of uncertainty in detailed snowpack simulations lies in the quality of meteorological forcings. The limited spatial resolution of common reanalysis and forecast data used as inputs for snowpack models usually makes it difficult to simulate the local horizontal heterogeneity of snowpack physical properties, especially in mountainous areas. Using satellite data to incorporate snowpack state observations into the simulations appears as an alluring way to improve the snow simulations, to account for spatial variability and to mitigate the impact of meteorological forcings uncertainties. This work presents an original study of the impact of the assimilation of visible and near-infrared reflectances into the detailed snowpack model SURFEX/ISBA-Crocus. We performed ensemble simulations by perturbing the atmospheric forcing consistently with its estimated uncertainty. In a first step, we performed assimilation experiments with synthetic imager (MODIS like) observations and a particle filter. The experiments were carried out at Col du Lautaret area (2100 m altitude, French Alps) over 5 hydrologic seasons. They provide a good insight about the potential and limitations of assimilating imager data to improve the representation of the snowpack. In particular, they demonstrate the significance of the temporal distribution of the observation to assimilate. In a second step, we assimilated actual MODIS data and evaluated the impact of the assimilation using snow measurements acquired during one winter season at Col du Lautaret. These real experiments enlighten the need for a relevant screening method for MODIS reflectances.

  8. Transitioning MODIS to VIIRS observations for Land: Surface Reflectance results, Status and Long-term Prospective

    Science.gov (United States)

    Vermote, E.

    2015-12-01

    Surface reflectance is one of the key products from VIIRS and as with MODIS, is used in developing several higher-order land products. The VIIRS Surface Reflectance (SR) IP is based on the heritage MODIS Collection 5 product (Vermote et al. 2002). The quality and character of surface reflectance depends on the accuracy of the VIIRS Cloud Mask (VCM) and aerosol algorithms and of course on the adequate calibration of the sensor. Early evaluation of the VIIRS SR product in the context of the maturity of the operational processing system known as the Interface Data Processing System (IDPS), has been a major focus of work to-date, but is now evolving into the development of a VIIRS suite of Climate Data Records produced by the NASA Land Science Investigator Processing System (SIPS). We will present the calibration performance and the role of the surface reflectance in calibration monitoring, the performance of the cloud mask with a focus on vegetation monitoring (no snow conditions), the performance of the aerosol input used in the atmospheric correction with quantitative results of the performance of the SR product over AERONET sites. Based on those elements and further assessment, we will address the readiness of the SR product for the production of higher-order land products such as Vegetation Indices, Albedo and LAI/FPAR, the its application to agricultural monitoring and in particular the integration of VIIRS data into the global agricultural monitoring (GLAM) system developed at UMd. Finally from the lessons learned, we will articulate a set of critical recommendations to ensure consistency and continuity of the JPSS mission with the MODIS data record.

  9. 基于MODIS/Aqua的胶州湾及青岛近海叶绿素a浓度年变化特征分析%Analysis on the Annual Change Characteristics of Chlorophyll-a Concentration in the Jiaozhou Bay and Qingdao Coastal Area Based on MODIS/Aqua

    Institute of Scientific and Technical Information of China (English)

    刘晓燕; 杨倩; 周燕

    2015-01-01

    利用2002-2013年MODIS/Aqua的Level 1B数据,经标准大气校正算法和叶绿素a浓度[chl-a]波段比经验算法(OC2M-HI),获得近12 a的胶州湾及青岛近海海域晴空的MOIDS/Aqua叶绿素a浓度.根据GOCI/COMS和MODIS/Aqua叶绿素a浓度产品在胶州湾及青岛近海交叉比较的结果[1],对2002-2013年的MODIS/Aqua [chl-a]进行了修正.基于修正后的MODIS/Aqua[chl-a]分析了胶州湾及青岛近海的叶绿素a浓度年变化特征.该海域的叶绿素a浓度大致呈现北高南低,湾内高于近海的特点,且每年空间分布趋势基本一致;近12a的[chl-a]呈小的上升趋势,胶州湾的上升趋势大于青岛近海.胶州湾跨海大桥建设前,其附近区域叶绿素a浓度以0.47 μg/L/year的趋势上升,基值为2.62μg/L;大桥开建及通车后,其附近叶绿素a浓度年变化趋势不明显,但基值明显增大(4.00 μg/L).

  10. Exploring Patterns and Effects of Aerosol Quantity Flag Anomalies in MODIS Surface Reflectance Products in the Tropics

    OpenAIRE

    Rasmus Fensholt; Kenneth Grogan

    2013-01-01

    The Moderate Resolution Imaging Spectroradiometer (MODIS) has been supplying a continuous data stream since 2000, lending to detailed time series analysis of the global terrestrial environment. This paper explores a quality anomaly present in the tropics relating to the aerosol quantity flag in the daily MODIS surface reflectance products (MOD09 series) and the 16-day Vegetation Index (VI) composite products (MOD13 series) derived from the daily observations. While the anomaly is to some exte...

  11. MODIS/Aqua MOD11C2 Land Surface Temperature/Emissivity 8-Day L3 Global 0.05Deg CMG

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The MODIS/Terra Land Surface Temperature and Emissivity (LST/E) products provide per-pixel temperature and emissivity values in a sequence of swath-based to...

  12. MODIS/AQUA MYD15A2H Leaf Area Index - Fraction of Photosynthetically Active Radiation 8-Day L4 Global 500 m Version 6

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The level-4 MODIS global Leaf Area Index (LAI) and Fraction of Photosynthetically Active Radiation (FPAR) product is composited every 8 days at 500-meter...

  13. MODIS/AQUA MYD13C1 Vegetation Indices 16-Day L3 Global 0.05Deg CMG Version 6

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The MODIS Vegetation Indices Version 6 product provides a Vegetation Index (VI) value at a per pixel basis. There are 2 primary vegetation layers. The algorithm for...

  14. MODOCGA: MODIS/Terra Ocean Reflectance Daily L2G-Lite Global 1 km SIN Grid Version 6

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The Version 6 Level 2 Gridded (L2G) Ocean Reflectance product consists of 1 kilometer reflectance data from MODIS bands 8-16. The product is referred to as ocean...

  15. Characterization of MODIS solar diffuser on-orbit degradation

    Science.gov (United States)

    Xiong, X.; Xie, X.; Angal, A.; Choi, J.; Sun, J.; Barnes, W. L.

    2007-09-01

    MODIS has 20 reflective solar bands (RSB) that are calibrated on-orbit using a solar diffuser (SD) and a solar diffuser stability monitor (SDSM). The MODIS SD bi-directional reflectance factor (BRF) was characterized pre-launch. Its on-orbit degradation is regularly monitored by the SDSM at wavelengths ranging from 0.41 to 0.94μm. During each SD/SDSM calibration event, the SDSM views alternately the sunlight directly through a fixed attenuation screen and the sunlight diffusely reflected from the SD panel. The time series of SDSM measurements (ratios of the SD view response to the Sun view response) is used to determine the SD BRF degradation at SDSM wavelengths. Since launch Terra MODIS has operated for more than seven years and Aqua for over five years. The SD panel on each MODIS instrument has experienced noticeable degradation with the largest changes observed in the VIS spectral region. This paper provides a brief description of MODIS RSB calibration methodology and SD/SDSM operational activities, and illustrates the SD on-orbit degradation results for both Terra and Aqua MODIS. It also discusses the impact on the SD degradation due to sensor operational activities and SD solar exposure time. Aqua MODIS has been operated under nearly the same condition for more than five years. Its SD annual degradation rate is estimated to be 2.7% at 0.41μm, 1.7% at 0.47μm, and less than 1.0% at wavelengths above 0.53μm. Terra MODIS, on the other hand, has experienced two different SD solar exposure conditions due to an SD door (SDD) operation related anomaly that occurred in May 2003 that had led to a decision to keep the SDD permanently at its "open" position. Prior to this event, Terra MODIS SD degradation rates were very similar to Aqua MODIS. Since then its SD has experienced much faster degradation rates due to more frequent solar exposure.

  16. Comparison of MODIS and VIIRS solar diffuser stability monitor performance

    Science.gov (United States)

    Xiong, Xiaoxiong; Fulbright, Jon; Angal, Amit; Sun, Junqiang; Wang, Zhipeng

    2012-11-01

    Launched in December 1999 and May 2002, Terra and Aqua MODIS have successfully operated for more than 12 and 10 years, respectively. MODIS reflective solar bands (RSB) are calibrated on-orbit by a solar diffuser (SD). Its on-orbit degradation, or the change in its bi-directional reflectance factor (BRF), is tracked by a solar diffuser stability monitor (SDSM). The MODIS SDSM makes alternate observations of direct sunlight through an attenuation screen (Sun view) and of sunlight reflected diffusely off the SD (SD view) during each SDSM calibration event. The MODIS SDSM has 9 detectors, covering wavelengths from 0.41 to 0.94 μm. Due to a design error in MODIS SDSM sub-system (identified post-launch), relatively large ripples were noticed in its Sun view responses. As a result, an alternative approach was developed by the MODIS calibration team to minimize the uncertainty in determining the SD on-orbit degradation. The first VIIRS, on-board the Suomi NPP spacecraft, was successfully launched in October 2011. It carries a MODIS-like SD and SDSM system for its RSB on-orbit calibration. Its design was improved based on lessons learned from MODIS. Operationally, the VIIRS SDSM is used more frequently than MODIS. VIIRS SDSM collects data using 8 individual detectors, covering a similar wavelength range as MODIS. This paper provides an overview of MODIS and VIIRS SDSM design features, their on-orbit operations, and calibration strategies. It illustrates their on-orbit performance in terms of on-orbit changes in SDSM detector on-orbit responses and on-orbit degradations of their SD. Results show that on-orbit changes of both MODIS and VIIRS SD BRF and SDSM response have similar wavelength dependency: the SD degradation is faster at shorter visible wavelengths while the decrease of SDSM detector responses (gains) is greater at longer near-infrared wavelengths.

  17. Critical reflectance derived from MODIS: Application for the retrieval of aerosol absorption over desert regions

    Science.gov (United States)

    Wells, Kelley C.; Martins, J. Vanderlei; Remer, Lorraine A.; Kreidenweis, Sonia M.; Stephens, Graeme L.

    2012-02-01

    The determination of aerosol direct radiative forcing over desert regions requires accurate information about the aerosol single-scattering albedo (SSA); however, the brightness of desert surfaces in the visible and near-IR range complicates the retrieval of aerosol optical properties using passive space-based measurements. Here we use the critical reflectance method to retrieve spectral aerosol absorption from space over North Africa, a desert region that is predominantly impacted by absorbing dust and biomass burning aerosol. We examine the sensitivity of the critical reflectance parameter to aerosol physical and optical properties that are representative of the region, and we find that the critical reflectance has low sensitivity to assumptions of aerosol size and refractive index for dust-like particles, except at scattering angles near 180°, which should be avoided with this method. We use our findings to retrieve spectral SSA from critical reflectance derived from Moderate Resolution Imaging Spectroradiometer (MODIS) reflectances in the vicinity of two Aerosol Robotic Network (AERONET) stations: Tamanrasset, in the Algerian Sahara, and Banizoumbou, in the Sahel. We retrieve lower aerosol SSAs at Banizoumbou, which is often impacted by dust-smoke mixtures, and higher SSAs at Tamanrasset, where pure desert dust is the dominant aerosol. Our results generally fall within the AERONET uncertainty envelopes, although at Banizoumbou we retrieve a spectral dependence different from that of AERONET. On the basis of our analysis, we expect to be able to retrieve SSA from critical reflectance for pure dust with an uncertainty of 0.02 and to provide spatial and spectral SSA information that will help reduce current uncertainties in the aerosol radiative forcing over desert regions.

  18. Development of a High Resolution BRDF/Albedo Product by Fusing Airborne CASI Reflectance with MODIS Daily Reflectance in the Oasis Area of the Heihe River Basin, China

    Directory of Open Access Journals (Sweden)

    Dongqin You

    2015-05-01

    Full Text Available A land-cover-based linear BRDF (bi-directional reflectance distribution function unmixing (LLBU algorithm based on the kernel-driven model is proposed to combine the compact airborne spectrographic imager (CASI reflectance with the moderate resolution imaging spectroradiometer (MODIS daily reflectance product to derive the BRDF/albedo of the two sensors simultaneously in the foci experimental area (FEA of the Heihe Watershed Allied Telemetry Experimental Research (HiWATER, which was carried out in the Heihe River basin, China. For each land cover type, an archetypal BRDF, which characterizes the shape of its anisotropic reflectance, is extracted by linearly unmixing from the MODIS reflectance with the assistance of a high-resolution classification map. The isotropic coefficients accounting for the differences within a class are derived from the CASI reflectance. The BRDF is finally determined by the archetypal BRDF and the corresponding isotropic coefficients. Direct comparisons of the cropland archetypal BRDF and CASI albedo with in situ measurements show good agreement. An indirect validation which compares retrieved BRDF/albedo with that of the MCD43A1 standard product issued by NASA and aggregated CASI albedo also suggests reasonable reliability. LLBU has potential to retrieve the high spatial resolution BRDF/albedo product for airborne and spaceborne sensors which have inadequate angular samplings. In addition, it can shorten the timescale for coarse spatial resolution product like MODIS.

  19. Adaption of the MODIS aerosol retrieval algorithm using airborne spectral surface reflectance measurements over urban areas: a case study

    Science.gov (United States)

    Jäkel, E.; Mey, B.; Levy, R.; Gu, X.; Yu, T.; Li, Z.; Althausen, D.; Heese, B.; Wendisch, M.

    2015-12-01

    MODIS (MOderate-resolution Imaging Spectroradiometer) retrievals of aerosol optical depth (AOD) are biased over urban areas, primarily because the reflectance characteristics of urban surfaces are different than that assumed by the retrieval algorithm. Specifically, the operational "dark-target" retrieval is tuned towards vegetated (dark) surfaces and assumes a spectral relationship to estimate the surface reflectance in blue and red wavelengths. From airborne measurements of surface reflectance over the city of Zhongshan, China, were collected that could replace the assumptions within the MODIS retrieval algorithm. The subsequent impact was tested upon two versions of the operational algorithm, Collections 5 and 6 (C5 and C6). AOD retrieval results of the operational and modified algorithms were compared for a specific case study over Zhongshan to show minor differences between them all. However, the Zhongshan-based spectral surface relationship was applied to a much larger urban sample, specifically to the MODIS data taken over Beijing between 2010 and 2014. These results were compared directly to ground-based AERONET (AErosol RObotic NETwork) measurements of AOD. A significant reduction of the differences between the AOD retrieved by the modified algorithms and AERONET was found, whereby the mean difference decreased from 0.27±0.14 for the operational C5 and 0.19±0.12 for the operational C6 to 0.10±0.15 and -0.02±0.17 by using the modified C5 and C6 retrievals. Since the modified algorithms assume a higher contribution by the surface to the total measured reflectance from MODIS, consequently the overestimation of AOD by the operational methods is reduced. Furthermore, the sensitivity of the MODIS AOD retrieval with respect to different surface types was investigated. Radiative transfer simulations were performed to model reflectances at top of atmosphere for predefined aerosol properties. The reflectance data were used as input for the retrieval methods. It

  20. Science impact of MODIS C5 calibration degradation and C6+ improvements

    Directory of Open Access Journals (Sweden)

    A. Lyapustin

    2014-07-01

    Full Text Available The Collection 6 (C6 MODIS land and atmosphere datasets are scheduled for release in 2014. C6 contains significant revisions of the calibration approach to account for sensor aging. This analysis documents the presence of systematic temporal trends in the visible and near-infrared (500 m bands of the Collection 5 (C5 MODIS Terra, and to lesser extent, in MODIS Aqua geophysical datasets. Sensor degradation is largest in the Blue band (B3 of the MODIS sensor on Terra and decreases with wavelength. Calibration degradation causes negative global trends in multiple MODIS C5 products including the dark target algorithm's aerosol optical depth over land and Ångström Exponent over the ocean, global liquid water and ice cloud optical thickness, as well as surface reflectance and vegetation indices, including the normalized difference vegetation index (NDVI and enhanced vegetation index (EVI. As the C5 production will be maintained for another year in parallel with C6, one objective of this paper is to raise awareness of the calibration-related trends for the broad MODIS user community. The new C6 calibration approach removes major calibrations trends in the Level 1B (L1B data. This paper also introduces an enhanced C6+ calibration of the MODIS dataset which includes an additional polarization correction (PC to compensate for the increased polarization sensitivity of MODIS Terra since about 2007, as well as de-trending and Terra–Aqua cross-calibration over quasi-stable desert calibration sites. The PC algorithm, developed by the MODIS ocean biology processing group (OBPG, removes residual scan angle, mirror side and seasonal biases from aerosol and surface reflectance (SR records along with spectral distortions of SR. Using the Multi-Angle Implementation of Atmospheric Correction (MAIAC algorithm over deserts, we have also developed a de-trending and cross-calibration method which removes residual decadal trends on the order of several tenths of one

  1. Using the Surface Reflectance MODIS Terra Product to Estimate Turbidity in Tampa Bay, Florida

    Directory of Open Access Journals (Sweden)

    Douglas L. Rickman

    2010-12-01

    Full Text Available Turbidity is a commonly-used index of the factors that determine light penetration in the water column. Consistent estimation of turbidity is crucial to design environmental and restoration management plans, to predict fate of possible pollutants, and to estimate sedimentary fluxes into the ocean. Traditional methods monitoring fixed geographical locations at fixed intervals may not be representative of the mean water turbidity in estuaries between intervals, and can be expensive and time consuming. Although remote sensing offers a good solution to this limitation, it is still not widely used due in part to required complex processing of imagery. There are satellite-derived products, including the Moderate Resolution Imaging Spectroradiometer (MODIS Terra surface reflectance daily product (MOD09GQ Band 1 (620–670 nm which are now routinely available at 250 m spatial resolution and corrected for atmospheric effect. This study shows this product to be useful to estimate turbidity in Tampa Bay, Florida, after rainfall events (R2 = 0.76, n = 34. Within Tampa Bay, Hillsborough Bay (HB and Old Tampa Bay (OTB presented higher turbidity compared to Middle Tampa Bay (MTB and Lower Tampa Bay (LTB.

  2. MODIS/COMBINED MCD43B4 Nadir BRDF-Adjusted Reflectance Reflectance 16-Day L3 Global 1km

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The MODerate-resolution Imaging Spectroradiometer (MODIS) BRDF/Albedo Model Parameters product (MCD43A1) contains three-dimensional (3D) data sets providing users...

  3. Critical Reflectance Derived from MODIS: Application for the Retrieval of Aerosol Absorption over Desert Regions

    Science.gov (United States)

    Wells, Kelley C.; Martins, J. Vanderlei; Remer, Lorraine A.; Kreidenweis, Sonia M.; Stephens, Graeme L.

    2012-01-01

    Aerosols are tiny suspended particles in the atmosphere that scatter and absorb sunlight. Smoke particles are aerosols, as are sea salt, particulate pollution and airborne dust. When you look down at the earth from space sometimes you can see vast palls of whitish smoke or brownish dust being transported by winds. The reason that you can see these aerosols is because they are reflecting incoming sunlight back to the view in space. The reason for the difference in color between the different types of aerosol is that the particles arc also absorbing sunlight at different wavelengths. Dust appears brownish or reddish because it absorbs light in the blue wavelengths and scatters more reddish light to space, Knowing how much light is scattered versus how much is absorbed, and knowin that as a function of wavelength is essential to being able to quantify the role aerosols play in the energy balance of the earth and in climate change. It is not easy measuring the absorption properties of aerosols when they are suspended in the atmosphere. People have been doing this one substance at a time in the laboratory, but substances mix when they are in the atmosphere and the net absorption effect of all the particles in a column of air is a goal of remote sensing that has not yet been completely successful. In this paper we use a technique based on observing the point at which aerosols change from brightening the surface beneath to darkening it. If aerosols brighten a surface. they must scatter more light to space. If they darken the surface. they must be absorbing more. That cross over point is called the critical reflectance and in this paper we show that critical reflectance is a monotonic function of the intrinsic absorption properties of the particles. This parameter we call the single scattering albedo. We apply the technique to MODIS imagery over the Sahara and Sahel regions to retrieve the single scattering albedo in seven wavelengths, compare these retrievals to ground

  4. EROS MODIS Land Surface Temperature: 2002-Present

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The EROS Moderate Resolution Imaging Spectroradiometer (eMODIS) Aqua Land Surface Temperature (LST) product is similar to the Land Processes Distributed Active...

  5. Validation of MODIS-derived bidirectional reflectivity retrieval algorithm in mid-infrared channel with field measurements.

    Science.gov (United States)

    Tang, Bo-Hui; Wu, Hua-; Li, Zhao-Liang; Nerry, Françoise

    2012-07-30

    This work addressed the validation of the MODIS-derived bidirectional reflectivity retrieval algorithm in mid-infrared (MIR) channel, proposed by Tang and Li [Int. J. Remote Sens. 29, 4907 (2008)], with ground-measured data, which were collected from a field campaign that took place in June 2004 at the ONERA (Office National d'Etudes et de Recherches Aérospatiales) center of Fauga-Mauzac, on the PIRRENE (Programme Interdisciplinaire de Recherche sur la Radiométrie en Environnement Extérieur) experiment site [Opt. Express 15, 12464 (2007)]. The leaving-surface spectral radiances measured by a BOMEM (MR250 Series) Fourier transform interferometer were used to calculate the ground brightness temperatures with the combination of the inversion of the Planck function and the spectral response functions of MODIS channels 22 and 23, and then to estimate the ground brightness temperature without the contribution of the solar direct beam and the bidirectional reflectivity by using Tang and Li's proposed algorithm. On the other hand, the simultaneously measured atmospheric profiles were used to obtain the atmospheric parameters and then to calculate the ground brightness temperature without the contribution of the solar direct beam, based on the atmospheric radiative transfer equation in the MIR region. Comparison of those two kinds of brightness temperature obtained by two different methods indicated that the Root Mean Square Error (RMSE) between the brightness temperatures estimated respectively using Tang and Li's algorithm and the atmospheric radiative transfer equation is 1.94 K. In addition, comparison of the hemispherical-directional reflectances derived by Tang and Li's algorithm with those obtained from the field measurements showed that the RMSE is 0.011, which indicates that Tang and Li's algorithm is feasible to retrieve the bidirectional reflectivity in MIR channel from MODIS data.

  6. Validation of MODIS-derived bidirectional reflectivity retrieval algorithm in mid-infrared channel with field measurements.

    Science.gov (United States)

    Tang, Bo-Hui; Wu, Hua-; Li, Zhao-Liang; Nerry, Françoise

    2012-07-30

    This work addressed the validation of the MODIS-derived bidirectional reflectivity retrieval algorithm in mid-infrared (MIR) channel, proposed by Tang and Li [Int. J. Remote Sens. 29, 4907 (2008)], with ground-measured data, which were collected from a field campaign that took place in June 2004 at the ONERA (Office National d'Etudes et de Recherches Aérospatiales) center of Fauga-Mauzac, on the PIRRENE (Programme Interdisciplinaire de Recherche sur la Radiométrie en Environnement Extérieur) experiment site [Opt. Express 15, 12464 (2007)]. The leaving-surface spectral radiances measured by a BOMEM (MR250 Series) Fourier transform interferometer were used to calculate the ground brightness temperatures with the combination of the inversion of the Planck function and the spectral response functions of MODIS channels 22 and 23, and then to estimate the ground brightness temperature without the contribution of the solar direct beam and the bidirectional reflectivity by using Tang and Li's proposed algorithm. On the other hand, the simultaneously measured atmospheric profiles were used to obtain the atmospheric parameters and then to calculate the ground brightness temperature without the contribution of the solar direct beam, based on the atmospheric radiative transfer equation in the MIR region. Comparison of those two kinds of brightness temperature obtained by two different methods indicated that the Root Mean Square Error (RMSE) between the brightness temperatures estimated respectively using Tang and Li's algorithm and the atmospheric radiative transfer equation is 1.94 K. In addition, comparison of the hemispherical-directional reflectances derived by Tang and Li's algorithm with those obtained from the field measurements showed that the RMSE is 0.011, which indicates that Tang and Li's algorithm is feasible to retrieve the bidirectional reflectivity in MIR channel from MODIS data. PMID:23038327

  7. The normalization of surface anisotropy effects present in SEVIRI reflectances by using the MODIS BRDF method

    DEFF Research Database (Denmark)

    Proud, Simon Richard; Zhang, Qingling; Schaaf, Crystal;

    2014-01-01

    . It is found that the MSG retrievals are stable and are of high-quality across much of the SEVIRI disk while maintaining a higher temporal resolution than the MODIS BRDF products. However, a number of circumstances are discovered whereby the BRDF model is unable to function correctly with the SEVIRI...

  8. Intercalibration of CERES, MODIS, and MISR reflected solar radiation and its application to albedo trends

    Science.gov (United States)

    Zhan, Yizhe; Davies, Roger

    2016-06-01

    Measurements on the Terra satellite by the Cloud and the Earth's Radiant Energy System (CERES), the Moderate Resolution Imaging Spectroradiometer (MODIS), and the Multiangle Imaging Spectroradiometer (MISR), between 2001 and 2015 over the polar regions, are analyzed in order to investigate the intercalibration differences between these instruments. Direct comparisons of colocated near-nadir radiances from CERES, MODIS, and MISR show relative agreement within 2.4% decade-1. By comparison with the CERES shortwave broadband, MODIS Collection 6 is getting brighter, by 1.0 ± 0.7% decade-1 in the red band and 1.4 ± 0.7% decade-1 in the near infrared. MISR's red and near-infrared bands, however, show darkening trends of -1.0 ± 0.6% decade-1 and -1.1 ± 0.6% decade-1, respectively. The CERES/MODIS or CERES/MISR visible and near IR radiance ratio is shown to have a significant negative correlation with precipitable water content over the Antarctic Plateau. The intercalibration results successfully correct the differential top-of-atmosphere trends in zonal albedos between CERES and MISR.

  9. Testing aerosol properties in MODIS Collection 4 and 5 using airborne sunphotometer observations in INTEX-B/MILAGRO

    Directory of Open Access Journals (Sweden)

    R. Levy

    2009-11-01

    AATS derived Angstrom exponents in going from C4 to C5 for MODIS-Terra, and a decrease in rms difference, hence an improvement, for the transition from C4 to C5 in MODIS-Aqua. Combining the AATS retrievals with in situ measurements of size-dependent aerosol extinction, we derive a suborbital measure of the aerosol submicron fraction (SMF of AOD and compare it to MODIS retrievals of aerosol fine mode fraction (FMF. Our analysis shows a significant rms-difference between the MODIS-Terra FMF and suborbitally-derived SMF of 0.17 for both C4 and C5. For MODIS-Aqua, there is a slight improvement in the transition from C4 to C5, with the rms-difference from AATS dropping from 0.23 to 0.16. The differences in MODIS C4 and C5 AOD in this limited data set can be traced to changes in the reflectances input to the aerosol retrievals. An extension of the C4-C5 comparisons from the area along the J31 flight track to a larger study region between 18–23° N and 93–100° W on each of the J31 flight days supports the finding of significant differences between MODIS C4 and C5.

  10. On-orbit performance of MODIS solar diffuser stability monitor

    Science.gov (United States)

    Xiong, Xiaoxiong (Jack); Angal, Amit; Choi, Taeyoung; Sun, Junqiang; Johnson, Eric

    2012-09-01

    MODIS reflective solar bands (RSB) calibration is provided by an on-board solar diffuser (SD). On-orbit changes in the SD bi-directional reflectance factor (BRF) are tracked by a solar diffuser stability monitor (SDSM). The SDSM consists of a solar integration sphere (SIS) with nine detectors covering wavelengths from 0.41 to 0.94 μm. It functions as a ratioing radiometer, making alternate observations of the sunlight through a fixed attenuation screen and the sunlight diffusely reflected from the SD during each scheduled SD/SDSM calibration event. Since launch, Terra and Aqua MODIS SD/SDSM systems have been operated regularly to support the RSB on-orbit calibration. This paper provides an overview of MODIS SDSM design functions, its operation and calibration strategies, and on-orbit performance. Changes in SDSM detector responses over time and their potential impact on tracking SD on-orbit degradation are examined. Also presented in this paper are lessons learned from MODIS SD/SDSM calibration system and improvements made to the VIIRS SD/SDSM system, including preliminary comparisons of MODIS and VIIRS SDSM on-orbit performance.

  11. MODIS On-orbit Calibration and Lessons Learned

    OpenAIRE

    Xiong, Xiaoxiong

    2012-01-01

    The Moderate Resolution Imaging Spectroradiometer (MODIS) is a key instrument for NASA’s Earth Observing System (EOS) Terra and Aqua missions. Since launch, Terra and Aqua MODIS have successfully operated for more than 12 and 10 years, respectively, and generated an unprecedented amount of data products for the science and user community over a wide range of applications. MODIS was developed with improved design and stringent calibration requirements over its heritage sensors in order to exte...

  12. MODIS and VIIRS Lunar Observations and Applications

    Science.gov (United States)

    Xiong, Xiaoxiong; Wang, Zhipeng; Sun, Junqiang; Angal, Amit Avinash; Fulbright, Jon; Butler, James

    2013-01-01

    Terra and Aqua MODIS have successfully operated for more than 13 and 11 years since their launch in 1999 and 2002, respectively. The VIIRS instrument on-board the S-NPP launched in 2011 has also operated for nearly 2 years. Both MODIS and VIIRS make observations in the reflective solar and thermal emissive regions and their on-orbit calibration and characterization are provided by a set of on-board calibrators (OBC). In addition, lunar observations have been made on a regular basis to support sensor on-orbit calibration. This paper provides a brief overview of MODIS and VIIRS instrument on-orbit calibration and characterization activities. It describes the approaches and strategies developed to schedule and perform on-orbit lunar observations. Specific applications of MODIS and VIIRS lunar observations discussed in this paper include radiometric calibration stability monitoring and performance assessment of sensor spatial characterization. Results derived from lunar observations, such as sensor response (or gain) trending and band-to-band registration, are compared with that derived from sensor OBC. The methodologies and applications presented in this paper can also be applied to other earth observing sensors.

  13. Remote Sensing of the Absorption Coefficients and Chlorophyll a Concentration in the U.S. Southern Middle Atlantic Bight from SeaWiFS and MODIS-Aqua

    Science.gov (United States)

    Pan, Xiaoju; Mannino, Antonio; Russ, Mary E.; Hooker, Stanford B.

    2008-01-01

    At present, satellite remote sensing of coastal water quality and constituent concentration is subject to large errors as compared to the capability of satellite sensors in oceanic waters. In this study, field measurements collected on a series of cruises within U.S. southern Middle Atlantic Bight (SMAB) were applied to improve retrievals of satellite ocean color products in order to examine the factors that regulate the bio-optical properties within the continental shelf waters of the SMAB. The first objective was to develop improvements in satellite retrievals of absorption coefficients of phytoplankton (a(sub ph)), colored dissolved organic matter (CDOM) (a(sub g)), non-pigmented particles (a(sub d)), and non-pigmented particles plus CDOM (a(sub dg)), and chlorophyll a concentration ([Chl_a]). Several algorithms were compared to derive constituent absorption coefficients from remote sensing reflectance (R(sub rs)) ratios. The validation match-ups showed that the mean absolute percent differences (MAPD) were typically less than 35%, although higher errors were found for a(sub d) retrievals. Seasonal and spatial variability of satellite-derived absorption coefficients and [Chl_a] was apparent and consistent with field data. CDOM is a major contributor to the bio-optical properties of the SMAB, accounting for 35-70% of total light absorption by particles plus CDOM at 443 nm, as compared to 30-45% for phytoplankton and 0-20% for non-pigmented particles. The overestimation of [Chl_a] from the operational satellite algorithms may be attributed to the strong CDOM absorption in this region. River discharge is important in controlling the bio-optical environment, but cannot explain all of the regional and seasonal variability of biogeochemical constituents in the SMAB.

  14. An Improved Endmember Selection Method Based on Vector Length for MODIS Reflectance Channels

    Directory of Open Access Journals (Sweden)

    Yuanliu Xu

    2015-05-01

    Full Text Available Endmember selection is the basis for sub-pixel land cover classifications using multiple endmember spectral mixture analysis (MESMA that adopts variant endmember matrices for each pixel to mitigate errors caused by endmember variability in SMA. A spectral library covering a large number of endmembers can account for endmember variability, but it also lowers the computational efficiency. Therefore, an efficient endmember selection scheme to optimize the library is crucial to implement MESMA. In this study, we present an endmember selection method based on vector length. The spectra of a land cover class were divided into subsets using vector length intervals of the spectra, and the representative endmembers were derived from these subsets. Compared with the available endmember average RMSE (EAR method, our approach improved the computational efficiency in endmember selection. The method accuracy was further evaluated using spectral libraries derived from the ground reference polygon and Moderate Resolution Imaging Spectroradiometer (MODIS imagery respectively. Results using the different spectral libraries indicated that MESMA combined with the new approach performed slightly better than EAR method, with Kappa coefficient improved from 0.75 to 0.78. A MODIS image was used to test the mapping fraction, and the representative spectra based on vector length successfully modeled more than 90% spectra of the MODIS pixels by 2-endmember models.

  15. Intercomparison of MODIS-Aqua C051 and C006 Level 3 Deep Blue AOD and Ångström exponent retrievals over the Sahara desert and the Arabian Peninsula during the period 2002-2014

    Science.gov (United States)

    Gkikas, Antonis; Basart, Sara; Korras-Carraca, Marios; Papadimas, Christos; Hatzianastassiou, Nikos; Sayer, Andrew; Hsu, Christina; Baldasano, Jose Maria

    2015-04-01

    Dust loads emitted from the arid regions of Northern Africa and the Arabian Peninsula account for the major portion of the global dust aerosol burden. Depending on prevailing atmospheric circulation they can be transported far away from their source areas. Considering the key role of dust aerosols to weather and climate a better description of their spatial and temporal variability it is an issue of great importance. The main target of the present study is to describe aerosols' regime over Northern Africa and Arabian Peninsula using Deep Blue aerosol optical depth (AOD550nm) and Ångström exponent (α412-470nm) measurements. Given the applied changes to the retrieval algorithm, emphasis is also given to the inter-comparison between the data from Collections 051 and 006. The analysis is performed using MODIS-Aqua daily Level 3 data at 1°x1° spatial resolution over the period 2002-2014. The study region extends from 20°W to 60°E and from 0° to 40°N. The obtained long-term geographical distributions reveal many similarities between C051 and C006 AOD retrievals. They both indicate a zone of high AODs along the parallel of 15°N, extending from the western coasts of Africa to Chad where the maximum values (~1.3) are recorded. In the Arabian Peninsula, the maximum AODs (up to 0.6) are found in Iraq. On the contrary, more apparent differences between the two collections are found for α412-470nm. It is evident a reduction of C006 retrievals, which is more pronounced across the Sahara desert. In C006, the α412-470nm values over the deserts of Northern Africa and Middle East mostly vary from 0 to 0.6 while higher values (up to 1.5) are observed in sub-sahel regions, west coasts of Saudi Arabia and Iran. During the study period, in both collections, AOD has decreased by up to 93% in N. Africa (northern parts of Algeria) while it has increased by up to 70% in the Middle East (northern parts of Iraq). Reversed tendencies are found for the α412-470nm retrievals. For

  16. An Overview of MODIS Radiometric Calibration and Characterization

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The Moderate Resolution Imaging Spectroradiometer (MODIS) is one of the key instruments for NASA's Earth Observing System (EOS), currently operating on both the Terra and Aqua satellites. The MODIS is a major advance over the previous generation of sensors in terms of its spectral, spatial, and temporal resolutions. It has 36 spectral bands: 20 reflective solar bands (RSB) with center wavelengths from 0.41 to 2.1μm and 16 thermal emissive bands (TEB) with center wavelengths from 3.7 to 14.4μm,making observations at three spatial resolutions: 250 m (bands 1-2), 500 m (bands 3-7), and 1km (bands 8-36). MODIS is a cross-track scanning radiometer with a wide field-of-view, providing a complete global coverage of the Earth in less than 2 days. Both Terra and Aqua MODIS went through extensive pre-launch calibration and characterization at various levels. In orbit, the calibration and characterization tasks are performed using its on-board calibrators (OBCs) that include a solar diffuser (SD) and a solar diffuser stability monitor (SDSM), a v-grooved flat panel blackbody (BB), and a spectro-radiometric calibration assembly (SRCA). In this paper, we present an overview of MODIS calibration and characterization activities, methodologies, and lessons learned from pre-launch characterization and in-orbit operation. Key issues discussed in this paper include in-orbit efforts of monitoring the noise characteristics of the detectors,tracking the solar diffuser and optics degradations, and updating the sensor's response versus scan angle.The experiences and lessons learned through MODIS have played and will continue to play major roles in the design and characterization of future sensors.

  17. Retrieval of seasonal dynamics of forest understory reflectance from semiarid to boreal forests using MODIS BRDF data

    Science.gov (United States)

    Pisek, Jan; Chen, Jing M.; Kobayashi, Hideki; Rautiainen, Miina; Schaepman, Michael E.; Karnieli, Arnon; Sprinstin, Michael; Ryu, Youngryel; Nikopensius, Maris; Raabe, Kairi

    2016-03-01

    Spatial and temporal patterns of forest background (understory) reflectance are crucial for retrieving biophysical parameters of forest canopies (overstory) and subsequently for ecosystem modeling. In this communication, we retrieved seasonal courses of understory normalized difference vegetation index (NDVI) from multiangular Moderate Resolution Imaging Spectroradiometer bidirectional reflectance distribution function (MODIS BRDF)/albedo data. We compared satellite-based seasonal courses of understory NDVI to understory NDVI values measured in different types of forests distributed along a wide latitudinal gradient (65.12°N-31.35°N). Our results indicated that the retrieval method performs well particularly over open forests of different types. We also demonstrated the limitations of the method for closed canopies, where the understory signal retrieval is much attenuated.

  18. Monitoring water turbidity and surface suspended sediment concentration of the Bagre Reservoir (Burkina Faso) using MODIS and field reflectance data

    Science.gov (United States)

    Robert, Elodie; Grippa, Manuela; Kergoat, Laurent; Pinet, Sylvain; Gal, Laetitia; Cochonneau, Gérard; Martinez, Jean-Michel

    2016-10-01

    Monitoring turbidity and Surface Suspended Sediment Concentration (SSSC) of inland waters is essential to address several important issues: erosion, sediment transport and deposition throughout watersheds, reservoir siltation, water pollution, human health risks, etc. This is especially important in regions with limited conventional monitoring capacities such as West Africa. In this study, we explore the use of Moderate Resolution Imaging Spectroradiometer data (MODIS, MOD09Q1 and MYD09Q1 products, red (R) and near infrared (NIR) bands) to monitor turbidity and SSSC for the Bagre Reservoir in Burkina Faso. High values ​​of these parameters associated with high spatial and temporal variability potentially challenge the methodologies developed so far for less turbid waters. Field measurements (turbidity, SSSC, radiometry) are used to evaluate different radiometric indices. The NIR/R ratio is found to be the most suited to retrieve SSSC and turbidity for both in-situ spectoradiometer measurements and satellite reflectance from MODIS. The spatio temporal variability of MODIS NIR/R together with rainfall estimated by the Tropical Rainforest Measuring Mission (TRMM) and altimetry data from Jason-2 is analyzed over the Bagre Reservoir for the 2000-2015 period. It is found that rain events of the early rainy season (February-March) through mid-rainy season (August) are decisive in triggering turbidity increase. Sediment transport is observed in the reservoir from upstream to downstream between June and September. Furthermore, a significant increase of 19% in turbidity values is observed between 2000 and 2015, mainly for the July to December period. It is especially well marked for August, with the central and downstream areas showing the largest increase. The most probable hypothesis to explain this evolution is a change in land use, and particularly an increase in the amount of bare soils, which enhances particle transport by runoff.

  19. OW NASA MODIS Aqua Ocean Color

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The dataset contains satellite-derived sea-surface ocean color (chlorophyll-a) measurements collected by means of the Moderate Resolution Imaging Spectroradiometer...

  20. Cross-calibration of the reflective solar bands of Terra MODIS and Landsat 7 Enhanced Thematic Mapper plus over PICS using different approaches

    Science.gov (United States)

    Angal, Amit; Brinkmann, Jake; Mishra, Nischal; Link, Daniel; Xiong, Xiaoxiong J.; Helder, Dennis

    2015-10-01

    Both Terra MODIS and Landsat 7 (L7) Enhanced Thematic Mapper Plus (ETM+) have been successfully operating for over 15 years to collect valuable measurements of the earth's land, ocean, and atmosphere. The land-viewing bands of both sensors are widely used in several scientific products such as surface reflectance, normalized difference vegetation index, enhanced vegetation index etc. A synergistic use of the multi-temporal measurements from both sensors can greatly benefit the science community. Previous effort from the MODIS Characterization Support Team (MCST) was focused on comparing the top-of-atmosphere reflectance of the two sensors over Libya 4 desert target. Uncertainties caused by the site/atmospheric BRDF, spectral response mismatch, and atmospheric water-vapor were also characterized. In parallel, an absolute calibration approach based on empirical observation was also developed for the Libya 4 site by the South Dakota State University's (SDSU) Image Processing Lab. Observations from Terra MODIS and Earth Observing One (EO-1) Hyperion were used to model the Landsat ETM+ TOA reflectance. Recently, there has been an update to the MODIS calibration algorithm, which has resulted in the newly reprocessed Collection 6 Level 1B calibrated products. Similarly, a calibration update to some ETM+ bands has also resulted in long-term improvements of its calibration accuracy. With these updates, calibration differences between the spectrally matching bands of Terra MODIS and L7 ETM+ over the Libya 4 site are evaluated using both approaches.

  1. Testing aerosol properties in MODIS (MOD04/MYD04 Collection 4 and 5 using airborne sunphotometer observations in INTEX-B/MILAGRO

    Directory of Open Access Journals (Sweden)

    J. Redemann

    2009-05-01

    derived Angstrom exponents in going from C4 to C5 for MODIS-Terra, and a decrease in rms difference, hence an improvement, for the transition from C4 to C5 in MODIS-Aqua. Combining the AATS retrievals with in situ measurements of size-dependent aerosol extinction, we derive a suborbital measure of the aerosol submicron fraction (SMF of AOD and compare it to MODIS retrievals of aerosol fine mode fraction (FMF. Our analysis shows a significant rms-difference between the MODIS-Terra FMF and suborbitally-derived SMF of 0.17 for both C4 and C5. For MODIS-Aqua, there is a slight improvement in the transition from C4 to C5, with the rms-difference from AATS dropping from 0.23 to 0.16. The differences in MODIS C4 and C5 AOD in this limited data set can be traced to changes in the reflectances input to the aerosol retrievals. An extension of the C4-C5 comparisons from the area along the J31 flight track to a larger study region between 18–23° N and 93–100° W on each of the J31 flight days supports the finding of significant differences between MODIS C4 and C5.

  2. Retrieved sea surface temperature analysis of MODIS and AMSR-E aboard AQUA satellite for the northern Indian Ocean%AQUA卫星的MODIS和AMSR-E反演的印度洋北部海域海表温度特征对比分析

    Institute of Scientific and Technical Information of China (English)

    霍文娟; 韩震

    2013-01-01

    In this paper, the northern Indian Ocean served as the study area. Characteristics of sea surface temperature retrieved from MODIS and AMSR-E sensor aboard AQUA satellite were analyzed from three aspects, namely, the location,the temperature curve and the inversion accuracy. The main characteristics showed that the difference of MODIS SST and the AMSR-E SST changed with the latitude obviously; AMSR-E SST failed to offer accurate sea surface temperature in the coastal region; the diversity of MODIS SST and AMSR-E SST changed with the temperature differences. In this paper, the retrieval accuracy of AMSR-E SST was often better than that of MODIS SST. The result of this study had important reference to the sea surface temperature quantitative inversion using the thermal infrared and passive microwave remote sensing technology.%以印度洋北部海域为研究区域,分别从地理位置、温度曲线和反演精度3个方面对AQUA卫星上的MODIS和AMSR-E反演的海表温度特征进行了对比分析。其主要特征表现为MODIS SST与AMSR-E SST之间的差异随纬度变化较为明显;在近岸区域,AMSR-E SST无法获得准确的海表面温度;MODIS SST与AMSR-E SST之间的差异随温度而不同;在本次研究中,AMSR-E SST反演精度总体优于MODIS SST。本次研究结果对利用热红外遥感和被动微波遥感进行海洋表面温度的定量反演具有重要的参考价值。

  3. Retrieval of a Temporal High-Resolution Leaf Area Index (LAI by Combining MODIS LAI and ASTER Reflectance Data

    Directory of Open Access Journals (Sweden)

    Yonghua Qu

    2014-12-01

    Full Text Available This paper aims to retrieve temporal high-resolution LAI derived by fusing MOD15 products (1 km resolution, field-measured LAI and ASTER reflectance (15-m resolution. Though the inversion of a physically based canopy reflectance model using high-resolution satellite data can produce high-resolution LAI products, the obstacle to producing temporal products is obvious due to the low temporal resolution of high resolution satellite data. A feasible method is to combine different source data, taking advantage of the spatial and temporal resolution of different sensors. In this paper, a high-resolution LAI retrieval method was implemented using a dynamic Bayesian network (DBN inversion framework. MODIS LAI data with higher temporal resolution were used to fit the temporal background information, which is then updated by new, higher resolution data, herein ASTER data. The interactions between the different resolution data were analyzed from a Bayesian perspective. The proposed method was evaluated using a dataset collected in the HiWater (Heihe Watershed Allied Telemetry Experimental Research experiment. The determination coefficient and RMSE between the estimated and measured LAI are 0.80 and 0.43, respectively. The research results suggest that even though the coarse-resolution background information differs from the high-resolution satellite observations, a satisfactory estimation result for the temporal high-resolution LAI can be produced using the accumulated information from both the new observations and background information.

  4. Global evaluation of the Collection 5 MODIS dark-target aerosol products over land

    Directory of Open Access Journals (Sweden)

    R. C. Levy

    2010-06-01

    Full Text Available NASA's MODIS sensors have been observing the Earth from polar orbit, from Terra since early 2000 and from Aqua since mid 2002. We have applied a consistent retrieval and processing algorithm to both sensors to derive the Collection 5 (C005 dark-target aerosol products over land. Here, we co-locate the MODIS field of view aerosol retrievals with Level 2 AERONET sunphotometer measurements at over 300 sites, and find 85 000 matched pairs that represent mutually cloud-free conditions. From these collocations, we validate the total aerosol optical depth (AOD or τ product, and define the expected error (EE as ±(0.05+0.15τ. Since we find that >66% (one standard deviation of MODIS AOD values compare to AERONET within EE, we can consider global AOD to be validated. However, MODIS does not compare as well to AERONET at particular sites and seasons. There are residual biases that are correlated with Ångstrom exponent, scattering angles, and scene reflectance conditions, resulting from assumptions about the aerosol optical properties and surface conditions that are not accurate everywhere. Although we conclude that the AOD over land is globally quantitative, MODIS-derived parameters of aerosol size over land (Ångström exponent, fine AOD are not. When separating data into those derived from Terra versus those from Aqua, scatterplots to AERONET are nearly indistinguishable. However, while Aqua is stable, Terra shows a slight trend in its bias with respect to AERONET; overestimating (by ~0.005 before 2004, and underestimating by similar magnitude after. This suggests small, but significant calibration uncertainties of <2%, which could lead to spurious long-term aerosol trends.

  5. MODIS and SeaWIFS on-orbit lunar calibration

    Science.gov (United States)

    Sun, Jielun; Eplee, R.E., Jr.; Xiong, X.; Stone, T.; Meister, G.; McClain, C.R.

    2008-01-01

    The Moon plays an important role in the radiometric stability monitoring of the NASA Earth Observing System's (EOS) remote sensors. The MODIS and SeaWIFS are two of the key instruments for NASA's EOS missions. The MODIS Protoflight Model (PFM) on-board the Terra spacecraft and the MODIS Flight Model 1 (FM1) on-board the Aqua spacecraft were launched on December 18, 1999 and May 4, 2002, respectively. They view the Moon through the Space View (SV) port approximately once a month to monitor the long-term radiometric stability of their Reflective Solar Bands (RSB). SeaWIFS was launched on-board the OrbView-2 spacecraft on August 1, 1997. The SeaWiFS lunar calibrations are obtained once a month at a nominal phase angle of 7??. The lunar irradiance observed by these instruments depends on the viewing geometry. The USGS photometric model of the Moon (the ROLO model) has been developed to provide the geometric corrections for the lunar observations. For MODIS, the lunar view responses with corrections for the viewing geometry are used to track the gain change for its reflective solar bands (RSB). They trend the system response degradation at the Angle Of Incidence (AOI) of sensor's SV port. With both the lunar observation and the on-board Solar Diffuser (SD) calibration, it is shown that the MODIS system response degradation is wavelength, mirror side, and AOI dependent. Time-dependent Response Versus Scan angle (RVS) Look-Up Tables (LUT) are applied in MODIS RSB calibration and lunar observations play a key role in RVS derivation. The corrections provided by the RVS in the Terra and Aqua MODIS data from the 412 nm band are as large as 16% and 13%, respectively. For SeaWIFS lunar calibrations, the spacecraft is pitched across the Moon so that the instrument views the Moon near nadir through the same optical path as it views the Earth. The SeaWiFS system gain changes for its eight bands are calibrated using the geometrically-corrected lunar observations. The radiometric

  6. Retrieval of seasonal dynamics of forest understory reflectance from semi-arid to boreal forests using MODIS BRDF data

    Science.gov (United States)

    Pisek, Jan; Chen, Jing; Kobayashi, Hideki; Rautiainen, Miina; Schaepman, Michael; Karnieli, Arnon; Sprintsin, Michael; Ryu, Youngryel; Nikopensius, Maris; Raabe, Kairi

    2016-04-01

    Ground vegetation (understory) provides an essential contribution to the whole-stand reflectance signal in many boreal, sub-boreal, and temperate forests. Accurate knowledge about forest understory reflectance is urgently needed in various forest reflectance modelling efforts. However, systematic collections of understory reflectance data covering different sites and ecosystems are almost missing. Measurement of understory reflectance is a real challenge because of an extremely high variability of irradiance at the forest floor, weak signal in some parts of the spectrum, spectral separability issues of over- and understory and its variable nature. Understory can consist of several sub-layers (regenerated tree, shrub, grasses or dwarf shrub, mosses, lichens, litter, bare soil), it has spatially-temporally variable species composition and ground coverage. Additional challenges are introduced by patchiness of ground vegetation, ground surface roughness, and understory-overstory relations. Due to this variability, remote sensing might be the only means to provide consistent data at spatially relevant scales. In this presentation, we report on retrieving seasonal courses of understory Normalized Difference Vegetation Index (NDVI) from multi-angular MODIS BRDF/Albedo data. We compared satellite-based seasonal courses of understory NDVI against an extended collection of different types of forest sites with available in-situ understory reflectance measurements. These sites are distributed along a wide latitudinal gradient on the Northern hemisphere: a sparse and dense black spruce forests in Alaska and Canada, a northern European boreal forest in Finland, hemiboreal needleleaf and deciduous stands in Estonia, a mixed temperate forest in Switzerland, a cool temperate deciduous broadleaf forest in Korea, and a semi-arid pine plantation in Israel. Our results indicated the retrieval method performs well particularly over open forests of different types. We also demonstrated

  7. Assessment of MODIS and VIIRS solar diffuser on-orbit degradation

    Science.gov (United States)

    Xiong, Xiaoxiong; Fulbright, Jon; Angal, Amit; Wang, Zhipeng; Geng, Xu; Butler, Jim

    2015-09-01

    Both MODIS and VIIRS instruments use a solar diffuser (SD) for their reflective solar bands (RSB) on-orbit calibration. On-orbit changes in SD bi-directional reflectance factor (BRF) are tracked by a solar diffuser stability monitor (SDSM) using its alternate measurements of the sunlight reflected off the SD panel and direct sunlight through a fixed attenuation screen. The SDSM calibration data are collected by a number of filtered detectors, covering wavelengths from 0.41 to 0.94μm. In this paper we describe briefly the Terra and Aqua MODIS and S-NPP VIIRS SDSM on-orbit operation and calibration activities and strategies, provide an overall assessment of their SDSM on-orbit performance, including wavelength-dependent changes in the SDSM detector responses and changes in their SD BRF, and discuss remaining challenging issues and their potential impact on RSB calibration quality. Due to different launch dates, operating configurations, and calibration frequencies, the Terra and Aqua MODIS and S-NPP VIIRS SD have experienced different amount of SD degradation. However, in general the shorter the wavelength, the larger is the SD on-orbit degradation. On the other hand, the larger changes in SDSM detector responses are observed at longer wavelengths in the near infrared (NIR).

  8. Space environment's effect on MODIS calibration

    Science.gov (United States)

    Dodd, J. L.; Wenny, B. N.; Chiang, K.; Xiong, X.

    2010-09-01

    The MODerate resolution Imaging Spectroradiometer flies on board the Earth Observing System (EOS) satellites Terra and Aqua in a sun-synchronous orbit that crosses the equator at 10:30 AM and 2:30 PM, respectively, at a low earth orbit (LEO) altitude of 705 km. Terra was launched on December 18,1999 and Aqua was launched on May 4, 2002. As the MODIS instruments on board these satellites continue to operate beyond the design lifetime of six years, the cumulative effect of the space environment on MODIS and its calibration is of increasing importance. There are several aspects of the space environment that impact both the top of atmosphere (TOA) calibration and, therefore, the final science products of MODIS. The south Atlantic anomaly (SAA), spacecraft drag, extreme radiative and thermal environment, and the presence of orbital debris have the potential to significantly impact both MODIS and the spacecraft, either directly or indirectly, possibly resulting in data loss. Efforts from the Terra and Aqua Flight Operations Teams (FOT), the MODIS Instrument Operations Team (IOT), and the MODIS Characterization Support Team (MCST) prevent or minimize external impact on the TOA calibrated data. This paper discusses specific effects of the space environment on MODIS and how they are minimized.

  9. Recent progress of MODIS solar diffuser on-orbit degradation characterization

    Science.gov (United States)

    Chen, H.; Wang, Z.; Sun, J.; Angal, A.; Xiong, X.

    2012-09-01

    An on-board Solar Diffuser (SD) is used for the MODIS reflective solar bands (RSB) calibration. Its on-orbit bidirectional reflectance factor (BRF) degradation is tracked using an on-board Solar Diffuser Stability Monitor (SDSM). The SDSM is a ratioing radiometer with nine detectors, covering wavelengths from 412 nm to 936 nm. During each scheduled SD calibration event, the SDSM makes alternate observations of the Sun and the sunlight reflected by the SD. To best match the SDSM detector signals from its Sun view and SD view, a fix attenuation screen is placed in its Sun view path. This paper provides a brief description of MODIS RSB on-orbit calibration and the use of its on-board SD and SDSM subsystem, including different approaches developed and used to track MODIS SD on-orbit degradation. It reports recent progress made to better characterize MODIS SD on-orbit degradation and to support MODIS Level 1B (L1B) calibration look-up table (LUT) updates for the upcoming collection 6 (C6) reprocessing. Results of both Terra and Aqua SD on-orbit degradation derived from newly improved SDSM Sun view screen vignetting function and response fitting strategy, and their impact on RSB calibration uncertainties are also presented.

  10. The MODIS 2.1-{micro}m channel -- correlation with visible reflectance for use in remote sensing of aerosol

    Energy Technology Data Exchange (ETDEWEB)

    Kaufman, Y.J.; Wald, A.E. [Goddard Space Flight Center, Greenbelt, MD (United States); Remer, L.A.; Li, R.R. [Science Systems and Applications, Inc., Lanham, MD (United States); Gao, B.C. [Naval Research Lab., Washington, DC (United States); Flynn, L. [Univ. of Hawaii, Honolulu, HI (United States). Hawaii Inst. of Geophysics and Planetology

    1997-09-01

    A new technique for remote sensing of aerosol over the land and for atmospheric correction of Earth imagery is developed. It is based on detection of dark surface targets in the blue and red channels, as in previous methods, but uses the 2.1-{micro}m channel, instead of the 3.75 {micro}m for their detection. A 2.1-{micro}m channel is present on ADEOS OCTS and GLI, and planned on EOS-MODIS and EOSP, and a similar 2.2-{micro}m channel is present on Landsat TM. The advantage of the 2.1-{micro}m channel over the 3.75-{micro}m channel is that it is not affected by emitted radiation. The 2.1-{micro}m channel is transparent to most aerosol types (except dust) and therefore can be used to detect dark surface targets. Correlation between the surface reflection in the blue (0.49 {micro}m), red (0.66 {micro}m), and 2.1 {micro}m is established using atmospherically corrected Landsat TM and AVIRIS aircraft images collected over the Eastern United States, Maine, and California and spectral data obtained from the ground and light aircraft near San Diego, CA.

  11. Intercomparison of CALIOP and MODIS aerosol optical depth retrievals

    OpenAIRE

    Kittaka, C.; Winker, D. M.; M. A. Vaughan; Omar, A.; Remer, L. A.

    2010-01-01

    The Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) is carried on the CALIPSO satellite and has acquired global aerosol profiles since June 2006. CALIPSO is flown in formation with the Aqua satellite as part of the A-train satellite constellation, so that a large number of coincident aerosol observations are available from CALIOP and the MODIS-Aqua instrument. This study compares column aerosol optical depth at 0.532 μm derived from CALIOP aerosol profiles with MODIS-Aqua 0.55 μm ae...

  12. MODIS/COMBINED MCD43A4 Nadir BRDF-Adjusted Reflectance 16-Day L3 Global 500m

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The MODerate-resolution Imaging Spectroradiometer (MODIS) BRDF/Albedo Model Parameters product (MCD43A1) contains three-dimensional (3D) data sets providing users...

  13. MODIS/COMBINED MCD43C4 Nadir BRDF- Adjusted Reflectance 16-Day L3 0.05Deg CMG

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The MODerate-resolution Imaging Spectroradiometer (MODIS) BRDF/Albedo Model Parameters product (MCD43A1) contains three-dimensional (3D) data sets providing users...

  14. Towards the assimilation of MODIS reflectance into the detailed snowpack model SURFEX/ISBA-Crocus.

    Science.gov (United States)

    Charrois, L.; Cosme, E.; Dumont, M.; Lafaysse, M.; Morin, S.; Libois, Q.; Picard, G.

    2015-12-01

    Numerical simulations of snow on the ground are used for numerous scientific and operational applications such as avalanche hazard forecasting. Although the chain of models used in French mountain ranges for meteorological analysis and forecast (SAFRAN) and detailed snowpack modeling (SURFEX/ISBA-Crocus) usually perform reasonably well, significant differences with snowpack observations are common and are primarily attributed to the uncertainties in meteorological input and to the heterogeneity of snowpack conditions at all scales. So far, no snow observation is assimilated into this model chain, so that simulation errors can accumulate over the winter season. Current efforts are devoted to the assimilation of data from visible and near-infrared imagers into the snowpack model. These efforts rely on the recently developed "TARTES" optical scheme that computes reflectances at various wavelengths using the vertical profile of the physical properties of snow predicted by the snowpack model. In a first step, we performed ensemble simulations by perturbing the atmospheric forcing consistently with its estimated uncertainty. These experiments showed that the simulated snowpack evolution is extremely sensitive to this uncertainty, and that the assimilation of observations can greatly improve model results. In a second step, we performed assimilation experiments using synthetic imager observations and a particle filter. The experiments were carried out for the location of Col du Lautaret area (French Alps) over 5 hydrologic seasons. They provide a good insight about the potential and limitations of assimilating imager data to improve the representation of the snowpack.

  15. AquaBuOY

    DEFF Research Database (Denmark)

    Weinstein, Alla; Fredrikson, Göran; Claeson, Lennart;

    2003-01-01

    This paper describes development of the mathematical model simulating ocean performance of an offshore wave energy point absorber device-AquaBuOY. The AquaBuOY is the next generation of the technology, based on the IPS point absorber system and the hose pump, both of Sweden. AquaEnergy Group Ltd......., USA, is developing the system in cooperation with RAMBOLL, Denmark. In March 2003 the Danish Energy Authority awarded a grant for a design study that includes development of the numerical model for the AquaBuOY operation, experimental testing and design optimisation. The scale model tests...... results from the model tests on mooring forces under survival conditions will be presented during the conference in conjunction with different footprint configurations and different mooring systems. Finally the performance data based on theoretical and experimental results will be presented for the AquaBu...

  16. Validation of MODIS aerosol retrievals and evaluation of potential cloud contamination in East Asia

    Institute of Scientific and Technical Information of China (English)

    XIA Xiang-ao; CHEN Hong-bin; WANG Pu-cai

    2004-01-01

    MODIS aerosol retrievals onboard Terra/Aqua and ground truth data obtained from AERONET(Aerosol Robtic Network) solar direct radiance measurements are collocated to evaluate the quality of the former in East Asia. AERONET stations in East Asia are separated into two groups according to their locations and the preliminary validation results for each station. The validation results showed that the accuracy of MODIS aerosol retrievals in East Asia is a little worse than that obtained in other regions such as Eastern U.S., Western Europe, Brazil and so on. The primary reason is due to the improper aerosol model used in MODIS aerosol retrieval algorithm, so it is of significance to characterize aerosol properties properly according to long term ground-based remote sensing or other relevant in situ observations in order to improve MODIS retrievals in East Asia. Cloud contamination is proved to be one of large errors, which is demonstrated by the significant relation between MODIS aerosol retrievals versus cloud fraction, as well as notable improvement of linear relation between satellite and ground aerosol data after potential cloud contamination screened. Hence, it is suggested that more stringent clear sky condition be set in use of MODIS aerosol data. It should be pointed out that the improvement might be offset by other error sources in some cases because of complex relation between different errors. Large seasonal variation of surface reflection and uncertainties associated with it result in large intercepts and random error in MODIS aerosol retrievals in northern inland of East Asia. It remains to be a big problem to retrieve aerosols accurately in inland characterized by relatively larger surface reflection than the requirement in MODIS aerosol retrieval algorithm.

  17. Advanced Spaceborne Thermal Emission and Reflection Radometer (ASTER) Enhanced Vegetation Index (EVI) Products from Global Earth Observation (GEO) Grid: An Assessment Using Moderate Resolution Imaging Spectroradiometer (MODIS) for Synergistic Applications

    OpenAIRE

    Satoshi Tsuchida; Tomoaki Miura; Hirokazu Yamamoto

    2012-01-01

    We assessed the compatibility of three Advanced Spaceborne Thermal Emission and Reflection Radometer (ASTER) based Enhanced Vegetation Index (EVI) products generated in the GEO Grid system to Moderate Resolution Imaging Spectroradiometer (MODIS) EVI. The three products were two forms of the two-band EVI with ASTER red and NIR bands but without a blue band and the original, three-band EVI computed with ASTER red and NIR, and MODIS blue reflectances. Our assessment results showed good compatibi...

  18. Calibration improvements for MODIS and VIIRS SWIR spectral bands

    Science.gov (United States)

    Xiong, Xiaoxiong; Angal, Amit; Fulbright, Jon; Lei, Ning; Mu, Qiaozhen; Wang, Zhipeng; Wu, Aisheng

    2015-09-01

    Both MODIS and VIIRS use a solar diffuser (SD) to calibrate their reflective solar bands (RSB), covering wavelengths from 0.41 to 2.3 μm. On-orbit changes of the SD bi-directional reflectance factor (BRF) are tracked by an on-board solar diffuser stability monitor (SDSM). The current SDSM design only covers the spectral range from 0.41 to 0.93 μm. In general, the SD degradation is strongly wavelength-dependent with larger degradation occurring at shorter wavelengths, and the degradation in the SWIR region is expected to be extremely small. As each mission continues, however, the impact due to SD degradation at SWIR needs to be carefully examined and the correction if necessary should be applied in order to maintain the calibration quality. For Terra MODIS, alternative approaches have been developed and used to estimate the SD degradation for its band 5 at 1.24 μm and a time-dependent correction has already been applied to the current level 1B (L1B) collection 6 (C6). In this paper, we present different methodologies that can be used to examine the SD degradation and their applications for both Terra and Aqua MODIS and S-NPP VIIRS SWIR calibration. These methodologies include but not limited to the use of lunar observations, Pseudo Invariant Calibration Sites (PICS), and deep convective clouds (DCC). A brief description of relative approaches and their use is also provided in this paper.

  19. Operationalizing a Research Sensor: MODIS to VIIRS

    Science.gov (United States)

    Grant, K. D.; Miller, S. W.; Puschell, J.

    2012-12-01

    The National Oceanic and Atmospheric Administration (NOAA) and NASA are jointly acquiring the next-generation civilian environmental satellite system: the Joint Polar Satellite System (JPSS). JPSS will replace the afternoon orbit component and ground processing system of the current Polar-orbiting Operational Environmental Satellites (POES) managed by NOAA. The JPSS satellite will carry a suite of sensors designed to collect meteorological, oceanographic, climatological, and solar-geophysical observations of the earth, atmosphere, and space. The primary sensor for the JPSS mission is the Visible/Infrared Imager Radiometer Suite (VIIRS) developed by Raytheon Space and Airborne Systems (SAS). The ground processing system for the JPSS mission is known as the Common Ground System (JPSS CGS), and consists of a Command, Control, and Communications Segment (C3S) and the Interface Data Processing Segment (IDPS) which are both developed by Raytheon Intelligence and Information Systems (IIS). The Moderate Resolution Imaging Spectroradiometer (MODIS) was developed by Raytheon SAS for the NASA Earth Observing System (EOS) as a research instrument to capture data in 36 spectral bands, ranging in wavelength from 0.4 μm to 14.4 μm and at varying spatial resolutions (2 bands at 250 m, 5 bands at 500 m and 29 bands at 1 km). MODIS data provides unprecedented insight into large-scale Earth system science questions related to cloud and aerosol characteristics, surface emissivity and processes occurring in the oceans, on land, and in the lower atmosphere. MODIS has flown on the EOS Terra satellite since 1999 and on the EOS Aqua satellite since 2002 and provided excellent data for scientific research and operational use for more than a decade. The value of MODIS-derived products for operational environmental monitoring motivated led to the development of an operational counterpart to MODIS for the next-generation polar-orbiting environmental satellites, the Visible/Infrared Imager

  20. Derivation of Land Surface Albedo at High Resolution by Combining HJ-1A/B Reflectance Observations with MODIS BRDF Products

    Directory of Open Access Journals (Sweden)

    Bo Gao

    2014-09-01

    Full Text Available Land surface albedo is an essential parameter for monitoring global/regional climate and land surface energy balance. Although many studies have been conducted on global or regional land surface albedo using various remote sensing data over the past few decades, land surface albedo product with a high spatio–temporal resolution is currently very scarce. This paper proposes a method for deriving land surface albedo with a high spatio–temporal resolution (space: 30 m and time: 2–4 days. The proposed method works by combining the land surface reflectance data at 30 m spatial resolution obtained from the charge-coupled devices in the Huanjing-1A and -1B (HJ-1A/B satellites with the Moderate Resolution Imaging Spectroradiometer (MODIS land surface bidirectional reflectance distribution function (BRDF parameters product (MCD43A1, which is at a spatial resolution of 500 m. First, the land surface BRDF parameters for HJ-1A/B land surface reflectance with a spatial–temporal resolutions of 30 m and 2–4 day are calculated on the basis of the prior knowledge from the MODIS BRDF product; then, the calculated high resolution BRDF parameters are integrated over the illuminating/viewing hemisphere to produce the white- and black-sky albedos at 30 m resolution. These results form the basis for the final land surface albedo derivation by accounting for the proportion of direct and diffuse solar radiation arriving at the ground. The albedo retrieved by this novel method is compared with MODIS land surface albedo products, as well as with ground measurements. The results show that the derived land surface albedo during the growing season of 2012 generally achieved a mean absolute accuracy of ±0.044, and a root mean square error of 0.039, confirming the effectiveness of the newly proposed method.

  1. Moderate Resolution Imaging Spectroradiometer (MODIS) Overview

    Science.gov (United States)

    U.S. Geological Survey

    2008-01-01

    The Moderate Resolution Imaging Spectroradiometer (MODIS) is an instrument that collects remotely sensed data used by scientists for monitoring, modeling, and assessing the effects of natural processes and human actions on the Earth's surface. The continual calibration of the MODIS instruments, the refinement of algorithms used to create higher-level products, and the ongoing product validation make MODIS images a valuable time series (2000-present) of geophysical and biophysical land-surface measurements. Carried on two National Aeronautics and Space Administration (NASA) Earth Observing System (EOS) satellites, MODIS acquires morning (EOS-Terra) and afternoon (EOS-Aqua) views almost daily. Terra data acquisitions began in February 2000 and Aqua data acquisitions began in July 2002. Land data are generated only as higher-level products, removing the burden of common types of data processing from the user community. MODIS-based products describing ecological dynamics, radiation budget, and land cover are projected onto a sinusoidal mapping grid and distributed as 10- by 10-degree tiles at 250-, 500-, or 1,000-meter spatial resolution. Some products are also created on a 0.05-degree geographic grid to support climate modeling studies. All MODIS products are distributed in the Hierarchical Data Format-Earth Observing System (HDF-EOS) file format and are available through file transfer protocol (FTP) or on digital video disc (DVD) media. Versions 4 and 5 of MODIS land data products are currently available and represent 'validated' collections defined in stages of accuracy that are based on the number of field sites and time periods for which the products have been validated. Version 5 collections incorporate the longest time series of both Terra and Aqua MODIS data products.

  2. Identifying crop specific signals for global agricultural monitoring based on the stability of daily multi-angular MODIS reflectance time series

    Science.gov (United States)

    Duveiller, G.; Lopez-Lozano, R.

    2013-12-01

    Global agricultural monitoring requires satellite Earth Observation systems that maximize the observation revisit frequency over the largest possible geographical coverage. Such compromise has thus far resulted in using a spatial resolution that is often coarser than desired. As a consequence, for many agricultural landscapes across the world, crop status can only be inferred from a mixed signal of the landscape (with a pixel size typically close to 1 km), composed of reflectance from neighbouring fields with potentially different crops, variable phenological behaviours and distinct management practices. MODIS has been providing, since 2000, a higher spatial resolution (~250m) that is closer to the size of individual fields in many agro-ecological landscapes. However, the challenge for operational crop specific monitoring remains to identify in time where a given crop has been sown during the current growing season. An innovative use of MODIS daily data is proposed for crop identification based on the stability of the multi-angular signal. MODIS is a whiskbroom sensor with a large swath. For any given place, consecutive MODIS observations are made with considerably different viewing angles according to the daily change in orbit. Consequently, the footprint of the observation varies considerably, thereby sampling the vicinity around the centre of the grid cell in which the time series is ultimately recorded in. If the consecutive observations that have sampled the vicinity provide similar NDVI values (for which BRDF effects are reduced), the resulting temporal signal is relatively stable. This stability indicated that the signal comes from a spatially homogeneous surface, such as a single large field covered by the same crop with similar agro-management practices. If the resulting temporal signal is noisy, it is probable that the consecutive daily observations have sampled different land uses, thus contaminating the signal. Such time series can therefore be

  3. Ocean color products retrieval and validation around China coast with MODIS

    Institute of Scientific and Technical Information of China (English)

    SUN Ling; GUO Maohua; WANG Xiaomei

    2010-01-01

    Waters along China coast are very turbid with high concentrations of suspended sediment nearly all the time, especially at the Hangzhou Bay, the Changjiang (Yangtze) River Estuary and the shoal along Jiangsu Province. In these turbid and optically complex waters, the standard MODIS ocean color products tend to have invalid values. Because the water-leaving radiances in the near-infrared (NIR) are significant resulting from the strong scattering of suspended particles, the standardMODIS atmospheric correction algorithm often gets no results or produces significant errors. And because of the complex water optical properties, the OC3 model used in the standard MODIS data processing tends to get extremely high chlorophyll-a (Chl-a) concentrations. In this paper, we present an atmospheric correction approach using MODIS short wave infrared (SWIR) bands based on the fact that water-leaving radiances are negligible in the SWlR region because of the extreme strong absorption of water even in turbid waters. A regional Chl-a concentration estimation model is also constructed for MODIS from in situ data. These algorithms are applied to MODIS Aqua data processing in the China coastal regions. In situ data collected in the Yellow Sea and the East China Sea in spring and autumn, 2003 are used to validate the performance. Reasonably good results have been obtained. It is noted that water-leaving reflectance in the NIR bands are significant in waters along the China coast with high sediment loadings. The satellite derived and in-situ reflectance spectra can match in the turbid waters along China coast, and there is relatively good linear relationship between satellite derived and in-situ reflectance. The RMSE value of Rrs(λ)is 0.0031 sr-1 for all the nine ocean color bands (412 to 869 nm). The satellite-derived Chl-a value is in the reasonable range and the root mean square percentage difference is 46.1%.

  4. Assessment of MODIS RSB Detector Uniformity Using Deep Convective Clouds

    Science.gov (United States)

    Chang, Tiejun; Xiong, Xiaoxiong (Jack); Angal, Amit; Mu, Qiaozhen

    2016-01-01

    For satellite sensor, the striping observed in images is typically associated with the relative multiple detector gain difference derived from the calibration. A method using deep convective cloud (DCC) measurements to assess the difference among detectors after calibration is proposed and demonstrated for select reflective solar bands (RSBs) of the Moderate Resolution Imaging Spectroradiometer (MODIS). Each detector of MODIS RSB is calibrated independently using a solar diffuser (SD). Although the SD is expected to accurately characterize detector response, the uncertainties associated with the SD degradation and characterization result in inadequacies in the estimation of each detector's gain. This work takes advantage of the DCC technique to assess detector uniformity and scan mirror side difference for RSB. The detector differences for Terra MODIS Collection 6 are less than 1% for bands 1, 3-5, and 18 and up to 2% for bands 6, 19, and 26. The largest difference is up to 4% for band 7. Most Aqua bands have detector differences less than 0.5% except bands 19 and 26 with up to 1.5%. Normally, large differences occur for edge detectors. The long-term trending shows seasonal oscillations in detector differences for some bands, which are correlated with the instrument temperature. The detector uniformities were evaluated for both unaggregated and aggregated detectors for MODIS band 1 and bands 3-7, and their consistencies are verified. The assessment results were validated by applying a direct correction to reflectance images. These assessments can lead to improvements to the calibration algorithm and therefore a reduction in striping observed in the calibrated imagery.

  5. Assessment of MODIS RSB detector uniformity using deep convective clouds

    Science.gov (United States)

    Chang, Tiejun; Xiong, Xiaoxiong (Jack); Angal, Amit; Mu, Qiaozhen

    2016-05-01

    For satellite sensor, the striping observed in images is typically associated with the relative multiple detector gain difference derived from the calibration. A method using deep convective cloud (DCC) measurements to assess the difference among detectors after calibration is proposed and demonstrated for select reflective solar bands (RSBs) of the Moderate Resolution Imaging Spectroradiometer (MODIS). Each detector of MODIS RSB is calibrated independently using a solar diffuser (SD). Although the SD is expected to accurately characterize detector response, the uncertainties associated with the SD degradation and characterization result in inadequacies in the estimation of each detector's gain. This work takes advantage of the DCC technique to assess detector uniformity and scan mirror side difference for RSB. The detector differences for Terra MODIS Collection 6 are less than 1% for bands 1, 3-5, and 18 and up to 2% for bands 6, 19, and 26. The largest difference is up to 4% for band 7. Most Aqua bands have detector differences less than 0.5% except bands 19 and 26 with up to 1.5%. Normally, large differences occur for edge detectors. The long-term trending shows seasonal oscillations in detector differences for some bands, which are correlated with the instrument temperature. The detector uniformities were evaluated for both unaggregated and aggregated detectors for MODIS band 1 and bands 3-7, and their consistencies are verified. The assessment results were validated by applying a direct correction to reflectance images. These assessments can lead to improvements to the calibration algorithm and therefore a reduction in striping observed in the calibrated imagery.

  6. Multisensor Comparisons for Validation of MODIS Vegetation Indices

    Institute of Scientific and Technical Information of China (English)

    CHENG Qian

    2006-01-01

    Vegetation indices (Ⅵ) are one of the standard science products available from the Moderate Resolution Imaging Spectroradiometer (MODIS). Validation of MODIS-Ⅵ products was an important prerequisite to using these variables for global modeling. In this study, validation of the MODIS-VI products including single-day MODIS, level 2 (gridded) daily MODIS surface reflectance (MOD09), 16-day composited MODIS (MOD13) was performed utilizing multisensor data from MODIS, Thematic Mapper (TM), and field radiometer, for a rice-planting region in southern China. The validation approach involved scaling up independent fine-grained datasets, including ground measurement and high spatial resolution imagery, to the coarser MODIS spatial resolutions. The 16-day composited MODIS reflectance and Ⅵ matched well with the ground measurement reflectance and Ⅵ. The Ⅵ of TM and MODIS were lower than the ground Ⅵ. The results demonstrated the accuracy, reliability, and utility of the MODIS-Ⅵ products for the study region.

  7. Global data for ecology and epidemiology: a novel algorithm for temporal Fourier processing MODIS data.

    Directory of Open Access Journals (Sweden)

    Jörn P W Scharlemann

    Full Text Available BACKGROUND: Remotely-sensed environmental data from earth-orbiting satellites are increasingly used to model the distribution and abundance of both plant and animal species, especially those of economic or conservation importance. Time series of data from the MODerate-resolution Imaging Spectroradiometer (MODIS sensors on-board NASA's Terra and Aqua satellites offer the potential to capture environmental thermal and vegetation seasonality, through temporal Fourier analysis, more accurately than was previously possible using the NOAA Advanced Very High Resolution Radiometer (AVHRR sensor data. MODIS data are composited over 8- or 16-day time intervals that pose unique problems for temporal Fourier analysis. Applying standard techniques to MODIS data can introduce errors of up to 30% in the estimation of the amplitudes and phases of the Fourier harmonics. METHODOLOGY/PRINCIPAL FINDINGS: We present a novel spline-based algorithm that overcomes the processing problems of composited MODIS data. The algorithm is tested on artificial data generated using randomly selected values of both amplitudes and phases, and provides an accurate estimate of the input variables under all conditions. The algorithm was then applied to produce layers that capture the seasonality in MODIS data for the period from 2001 to 2005. CONCLUSIONS/SIGNIFICANCE: Global temporal Fourier processed images of 1 km MODIS data for Middle Infrared Reflectance, day- and night-time Land Surface Temperature (LST, Normalised Difference Vegetation Index (NDVI, and Enhanced Vegetation Index (EVI are presented for ecological and epidemiological applications. The finer spatial and temporal resolution, combined with the greater geolocational and spectral accuracy of the MODIS instruments, compared with previous multi-temporal data sets, mean that these data may be used with greater confidence in species' distribution modelling.

  8. Validation and empirical correction of MODIS AOTand AE over ocean

    OpenAIRE

    N. A. J. Schutgens; Nakata, M; Nakajima, T.

    2013-01-01

    We present a validation study of Coll. 5 MODIS level 2 Aqua and Terra AOT and AE over ocean by comparison to coastal and island AERONET sites for the years 2003–2009. We show that MODIS AOT exhibits significant biases due to windspeed and cloudiness of the observed scene, while MODIS AE although overall unbiased, exhibits less spatial contrast on global scales than the AERONET observations. The same behaviour can be seen when MODIS AOT is compared against marine AERONET data, suggesting that ...

  9. Comparison of AOD between CALIPSO and MODIS: significant differences over major dust and biomass burning regions

    Directory of Open Access Journals (Sweden)

    X. Ma

    2013-09-01

    Full Text Available Cloud–Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO provide global vertical profiles of aerosol optical properties for the first time. In this study, we employed about 6 yr (2006–2011 of CALIPSO level 3 monthly mean gridded aerosol optical depth (AOD products (daytime and nighttime for cloud-free conditions, to compare with the Moderate Resolution Imaging Spectroradiometer (MODIS Terra/Aqua level 3 monthly mean AOD dataset for the same time period. While the spatial distribution and seasonal variability of CALIPSO AOD is generally consistent with that of MODIS, CALIPSO is overall lower than MODIS as MODIS has higher frequency than CALIPSO for most bins of AOD. The correlation between MODIS and CALIPSO is better over ocean than over land. We focused on four regions that have large systematic differences: two over dust regions (the Sahara and Northwest China and two over biomass burning regions (South Africa and South America. It is found that CALIPSO AOD is significantly lower than MODIS AOD over dust regions during the whole time period, with a maximum difference of 0.3 over the Saharan region and 0.25 over Northwest China. For biomass burning regions, CALIPSO AOD is significantly higher than MODIS AOD over South Africa, with a maximum difference of 0.25. Additionally CALIPSO AOD is slightly higher than MODIS AOD over South America for most of the time period, with a few exceptions in 2006, 2007, and 2010, when biomass burning is significantly stronger than during other years. We analyzed the impact of the satellite spatial and temporal sampling issue by using level 2 CALIPSO and MODIS products, and these systematic differences can still be found. The results of this study indicate that systematic differences of CALIPSO relative to MODIS are closely associated with aerosol types, which vary by location and season. Large differences over dust and biomass burning regions may suggest that assumptions made in satellite

  10. Characterization of MODIS VIS/NIR spectral band detector-to-detector differences

    Science.gov (United States)

    Xiong, X.; Sun, J.; Meister, G.; Kwiatkowska, E.; Barnes, W. L.

    2008-08-01

    MODIS has 36 spectral bands with wavelengths in the visible (VIS), near-infrared (NIR), short-wave infrared (SWIR), mid-wave infrared (MWIR), and long-wave infrared (LWIR). It makes observations at three nadir spatial resolutions: 0.25km for bands 1-2 (40 detectors per band), 0.5km for bands 3-7 (20 detectors per band), and 1km for bands 8-36 (10 detectors per band). The VIS, NIR, and SWIR are the reflective solar bands (RSB), which are calibrated on-orbit by a solar diffuser (SD) and a solar diffuser stability monitor (SDSM). The bi-directional reflectance factor (BRF) of the SD provides a RSB calibration reference and its on-orbit changes are tracked by the SDSM. In addition, MODIS lunar observations are regularly scheduled and used to track the RSB calibration stability. On-orbit observations show that the changes in detector response are wavelength and scan angle dependent. In this study, we focus on detector-to-detector calibration differences in the MODIS VIS/NIR spectral bands, which are determined using SD and lunar observations, while the calibration performance is evaluated using the Earth view (EV) level 1B (L1B) data products. For Aqua MODIS, the detector calibration differences and their impact are also characterized using standard ocean color data products. The current calibration approach for MODIS RSB carries a band-averaged response versus scan angle (RVS) correction. The results from this study suggest that a detector-based RVS correction should, due to changes in the scan mirror's optical properties, be implemented in order to maintain and improve the current RSB L1B data product quality, particularly, for several VIS bands in Terra MODIS.

  11. View-angle consistency in reflectance, optical thickness and spherical albedo of marine water-clouds over the northeastern Pacific through MISR-MODIS fusion

    Science.gov (United States)

    Liang, Lusheng; Di Girolamo, Larry; Platnick, Steven

    2009-05-01

    View-angle consistency in bidirectional reflectance factor (BRF), optical thickness and spherical albedo is examined for marine water clouds over a region of the northeastern Pacific using six years of fused Moderate Resolution Imaging Spectroradiometer (MODIS) and Multiangle Imaging SpectroRadiometer (MISR) data. Consistency is quantified by the root-mean-square of relative differences between MISR-measured BRF and their plane-parallel values and variation of plane-parallel retrieved optical thickness and spherical albedo across multiple view-angles. Probability distribution functions of consistency show that, for example, these clouds are angularly consistent within 5% in BRF, optical thickness and spherical albedo 72.2%, 39.0% and 81.1% of the time, respectively. We relate angular consistency to the spatial variability of nadir-BRF, thus allowing us to potentially identify, with a prescribed confidence level, which MODIS microphysical retrievals within the MISR swath meet the plane-parallel assumption to within any desired range in view-angle consistency.

  12. Comparison of MODIS and VIIRS cloud properties with ARM ground-based observations over Finland

    Science.gov (United States)

    Sporre, Moa K.; O'Connor, Ewan J.; Håkansson, Nina; Thoss, Anke; Swietlicki, Erik; Petäjä, Tuukka

    2016-07-01

    Cloud retrievals from the Moderate Resolution Imaging Spectroradiometer (MODIS) instruments aboard the satellites Terra and Aqua and the Visible Infrared Imaging Radiometer Suite (VIIRS) instrument aboard the Suomi-NPP satellite are evaluated using a combination of ground-based instruments providing vertical profiles of clouds. The ground-based measurements are obtained from the Atmospheric Radiation Measurement (ARM) programme mobile facility, which was deployed in Hyytiälä, Finland, between February and September 2014 for the Biogenic Aerosols - Effects on Clouds and Climate (BAECC) campaign. The satellite cloud parameters cloud top height (CTH) and liquid water path (LWP) are compared with ground-based CTH obtained from a cloud mask created using lidar and radar data and LWP acquired from a multi-channel microwave radiometer. Clouds from all altitudes in the atmosphere are investigated. The clouds are diagnosed as single or multiple layer using the ground-based cloud mask. For single-layer clouds, satellites overestimated CTH by 326 m (14 %) on average. When including multilayer clouds, satellites underestimated CTH by on average 169 m (5.8 %). MODIS collection 6 overestimated LWP by on average 13 g m-2 (11 %). Interestingly, LWP for MODIS collection 5.1 is slightly overestimated by Aqua (4.56 %) but is underestimated by Terra (14.3 %). This underestimation may be attributed to a known issue with a drift in the reflectance bands of the MODIS instrument on Terra. This evaluation indicates that the satellite cloud parameters selected show reasonable agreement with their ground-based counterparts over Finland, with minimal influence from the large solar zenith angle experienced by the satellites in this high-latitude location.

  13. Retrieval of Secchi disk depth in the Yellow Sea and East China Sea using 8-day MODIS data

    International Nuclear Information System (INIS)

    Secchi disk depth (SDD), is widely used as an indicator of water clarity. The traditional sampling method is not only time-consuming and labor-intensive but also limited in terms of temporal and spatial coverage. Remote sensing technology may deal with these limitations. In this paper, the applicability of 8-day MODIS-Aqua remote sensing reflectance data with 4 km spatial resolution for estimating water clarity in the Yellow Sea and the East China Sea was investigated. Field data such as Secchi depths were collected from two cruises conducted in the Yellow Sea and the East China Sea from 5 May to 7 June 2009. A three-band algorithm to retrieve SDD was developed based on remote sensing reflectance at bands of 488, 555, and 678 nm, which performed better than single-band model and band ratio algorithm, with a determination coefficient of 0.72 and a mean relative error of 19%. This suggests that 8-day MODIS-Aqua products of remote sensing reflectance could be used to assess water transparency in the study area

  14. Long-term Calibration Performance of MODIS Thermal Emissive Bands

    OpenAIRE

    Wenny, B.; Wu, A; Madhavan, S; Z. Wang; N. Chen; Li, Y.; Xiong, X

    2012-01-01

    Terra and Aqua MODIS, key instruments for NASA’s Earth Observing System missions, have operated continuously for more than 12 and 10 years respectively. The science products generated from MODIS data are used worldwide in studies of the Earth’s ocean, land, and atmosphere systems. As the sensors age well past their prime design life of 6 years, understanding the instrument on-orbit performance is imperative to continued production of high quality calibrated data. The 16 thermal emissive bands...

  15. Cloud removal methodology from MODIS snow cover product

    OpenAIRE

    Gafurov, A.; Bárdossy, A.

    2009-01-01

    The Moderate Resolution Imaging Spectroradiometer (MODIS) employed by Terra and Aqua satellites provides spatially snow covered data with 500 m and daily temporal resolution. It delivers public domain data in raster format. The main disadvantage of the MODIS sensor is that it is unable to record observations under cloud covered regions. This is why this study focuses on estimating the pixel cover for cloud covered areas where no information is available. Our step to this product involves empl...

  16. MODIS/TERRA MOD11A2 Land Surface Temperature & Emissivity 8-Day L3 Global 1km Version 6

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The MODIS/Aqua Land Surface Temperature and Emissivity (LST/E) products provide per-pixel temperature and emissivity values in a sequence of swath-based global...

  17. Improved VIIRS and MODIS SST Imagery

    OpenAIRE

    Irina Gladkova; Alexander Ignatov; Fazlul Shahriar; Yury Kihai; Don Hillger; Boris Petrenko

    2016-01-01

    Moderate Resolution Imaging Spectroradiometers (MODIS) and Visible Infrared Imaging Radiometer Suite (VIIRS) radiometers, flown onboard Terra/Aqua and Suomi National Polar-orbiting Partnership (S-NPP)/Joint Polar Satellite System (JPSS) satellites, are capable of providing superior sea surface temperature (SST) imagery. However, the swath data of these multi-detector sensors are subject to several artifacts including bow-tie distortions and striping, and require special pre-processing steps. ...

  18. Introduction to MODIS Collection 6 'Deep Blue' aerosol products and strategy for cirrus-signal correction in AOD retrievals using 1.38 μm reflectance data

    Science.gov (United States)

    Lee, J.; Hsu, N. C.; Sayer, A. M.; Bettenhausen, C.

    2012-12-01

    This study shows the characteristics of the Moderate Resolution Imaging Spectroradiometer (MODIS) Collection 6 Deep Blue aerosol products (hereafter, C006 DB products) and a strategy for correcting cirrus-signal in the aerosol optical depth (AOD) retrievals. The C006 DB products have several changes over the C005, including extended coverage, surface reflectance model, aerosol microphysical model, and cloud screening, etc. One of the new features is the inclusion of pixel-level uncertainty estimates on the retrieved AOD. These uncertainty estimates have been determined based on a validation against Aerosol Robotic Network (AERONET) direct-Sun AOD measurements, and are parameterized as a function of AOD, viewing geometry, and retrieval quality flag. This will provide users with a simple way to assess the uncertainty on Deep Blue AOD data for their particular application of interest. Preliminary results show strong agreement with AERONET, suggesting that the Deep Blue algorithm performs as well as other state-of-the-art satellite AOD datasets. In addition, a strategy for cirrus-signal correction in the retrieved AOD is presented. The cirrus reflectance at each wavelength to be used in the aerosol retrieval algorithms is determined by the relationships between reflectances at 1.38 μm and the aerosol bands and subtracted from the original TOA reflectance values assuming linear relationship for the optically thin case (ρ1.38 < 0.05). Since the 1.38 μm band is located in the strong water vapor absorption band, thus representing cirrus signal only, the slope between the 1.38 μm reflectance values and minimum reflectance values at each aerosol band for the corresponding values at 1.38 μm can be used to convert the 1.38 μm reflectance to the cirrus reflectance at each wavelength. Then, the cirrus-signal-corrected AOD can be retrieved by using the corrected reflectance data as input data into the aerosol retrieval algorithms. The retrieval results show that the AOD

  19. Validation and empirical correction of MODIS AOT and AE over ocean

    OpenAIRE

    N. A. J. Schutgens; Nakata, M; Nakajima, T.

    2013-01-01

    We present a validation study of Collection 5 MODIS level 2 Aqua and Terra AOT (aerosol optical thickness) and AE (Ångström exponent) over ocean by comparison to coastal and island AERONET (AErosol RObotic NETwork) sites for the years 2003–2009. We show that MODIS (MODerate-resolution Imaging Spectroradiometer) AOT exhibits significant biases due to wind speed and cloudiness of the observed scene, while MODIS AE, although overall unbiased, exhibits less spatial contrast on global scales than ...

  20. Science impact of MODIS C5 calibration degradation and C6+ improvements

    OpenAIRE

    A. Lyapustin; Wang, Y.; Xiong, X; Meister, G.; Platnick, S.; Levy, R.; Franz, B.; S. Korkin; T. Hilker; Tucker, J; Hall, F; Sellers, P.; Wu, A; Angal, A.

    2014-01-01

    The Collection 6 (C6) MODIS (Moderate Resolution Imaging Spectroradiometer) land and atmosphere data sets are scheduled for release in 2014. C6 contains significant revisions of the calibration approach to account for sensor aging. This analysis documents the presence of systematic temporal trends in the visible and near-infrared (500 m) bands of the Collection 5 (C5) MODIS Terra and, to lesser extent, in MODIS Aqua geophysical data sets. Sensor degradation is largest in the b...

  1. Characterization of MODIS SD screen vignetting function using observations from spacecraft yaw maneuvers

    Science.gov (United States)

    Wang, Zhipeng; Xiong, Xiaoxiong

    2009-08-01

    The MODIS reflective solar bands (RSB) include both the low-gain and high-gain spectral bands depending on their specific applications. MODIS RSBs are calibrated on-orbit by an on-board solar diffuser. In order to avoid detector response saturation when calibrating the high-gain bands, an optional attenuation screen, made of a metal plate with pinhole arrays, is placed in front of the SD panel. Since no pre-launch system-level characterization was made for the SD screen (SDS) vignetting function (VF), a series of spacecraft (Terra and Aqua) yaw maneuvers were carried out to perform on-orbit characterization of the VF. Assuming that the low-gain bands and the high-gain bands have the same VF, the current VF was derived from yaw observations using the MODIS low-gain bands through taking the ratio of their SD responses with and without the SDS in place. In this study, we attempt to characterize the SDS VF directly using detector responses of individual high-gain bands with the SDS in place only. The corresponding SD responses without the SDS, not available from measurements due to saturation, are calculated using detector gains, the SD bi-directional reflectance factor (BRF), and the view geometry that matches the yaw observations with the SDS in place. Results and discussions are focused on the band dependent and detector dependent features of the SDS VF, and their potential impact on the RSB calibration.

  2. Generating a Long-Term Land Data Record from the AVHRR and MODIS Instruments

    Science.gov (United States)

    Pedelty, Jeffrey; Devadiga, Sadashiva; Masuoka, Edward; Brown, Molly; Pinzon, Jorge; Tucker, Compton; Vermote, Eric; Prince, Stephen; Nagol, Jyotheshwar; Justice, Christopher; Roy, David; Ju, Junchang; Schaaf, Crystal; Liu, Jicheng; Privette, Jeffrey; Pincheiro, Ana

    2007-01-01

    The goal of NASA's Land Long Term Iiata Record (LTDR) project is to produce a consistent long term data set from the AVHRR and MODIS instruments for land climate studies. The project will create daily surface reflectance and normalized difference vegetation index (NDVI) products at a resolution of 0.05 deg., which is identical to the Climate Modeling Grid (CMG) used for MODIS products from EOS Terra and Aqua. Higher order products such as burned area, land surface temperature, albedo, bidirectional reflectance distribution function (BRDF) correction, leaf area index (LAI), and fraction of photosyntheticalIy active radiation absorbed by vegetation (fPAR), will be created. The LTDR project will reprocess Global Area Coverage (GAC) data from AVHRR sensors onboard NOAA satellites by applying the preprocessing improvements identified in the AVHRR Pathfinder Il project and atmospheric and BRDF corrections used in MODIS processing. The preprocessing improvements include radiometric in-flight vicarious calibration for the visible and near infrared channels and inverse navigation to relate an Earth location to each sensor instantaneous field of view (IFOV). Atmospheric corrections for Rayleigh scattering, ozone, and water vapor are undertaken, with aerosol correction being implemented. The LTDR also produces a surface reflectance product for channel 3 (3.75 micrometers). Quality assessment (QA) is an integral part of the LTDR production system, which is monitoring temporal trands in the AVHRR products using time-series approaches developed for MODIS land product quality assessment. The land surface reflectance products have been evaluated at AERONET sites. The AVHRR data record from LTDR is also being compared to products from the PAL (Pathfinder AVHRR Land) and GIMMS (Global Inventory Modeling and Mapping Studies) systems to assess the relative merits of this reprocessing vis-a-vis these existing data products. The LTDR products and associated information can be found at

  3. Comparison of AOD between CALIPSO and MODIS: significant differences over major dust and biomass burning regions

    Directory of Open Access Journals (Sweden)

    X. Ma

    2012-11-01

    Full Text Available Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO provide, for the first time, global vertical profiles of aerosol optical properties, but further research is needed to evaluate the CALIPSO products. In this study, we employed about 6 yr (2006–2011 of CALIPSO level-3 monthly mean gridded aerosol optical depth (AOD products (daytime and nighttime, for cloud free conditions, to compare with the MODIS Terra/Aqua level-3 monthly mean AOD dataset for the same time period. While the spatial distribution and seasonal variability of CALIPSO AOD is generally consistent with that of MODIS, CALIPSO is overall lower than MODIS as much more of the CALIPSO data is smaller than 0.1, while more of the MODIS data is greater than 0.1. We will focus on four regions that have large systematic differences: two over dust regions (the Sahara and Northwest China and two over biomass burning regions (South Africa and South America. It is found that CALIPSO AOD is significantly lower than MODIS AOD over dust regions during the whole time period, with a maximum low bias of 0.3 over the Saharan region, and 0.25 over Northwest China. For biomass burning regions, CALIPSO AOD is significantly higher than MODIS AOD over South Africa, with a maximum high bias of 0.25. Additionally CALIPSO AOD is slightly higher than MODIS AOD over South America for most of the time period, with a few exceptions in 2006, 2007, and 2010, when biomass burning is significantly stronger than during other years. The results in this study indicate that systematic biases of CALIPSO relative to MODIS are closely associated with aerosol types, which vary by location and season. Large differences over dust and biomass burning regions may suggest that assumptions made in satellite retrievals, such as the assumed lidar ratios for CALIPSO retrievals over dust and biomass burning regions, or the surface reflectance information and/or the aerosol model utilized by MODIS algorithm

  4. Validation of the MODIS "Clear-Sky" Surface Temperature of the Greenland Ice Sheet

    Science.gov (United States)

    Hall, Dorothy K.; Koenig, L. S.; DiGirolamo, N. E.; Comiso, J.; Shuman, C. A.

    2011-01-01

    Surface temperatures on the Greenland Ice Sheet have been studied on the ground, using automatic weather station (AWS) data from the Greenland-Climate Network (GC-Net), and from analysis of satellite sensor data. Using Advanced Very High Frequency Radiometer (AVHRR) weekly surface temperature maps, warming of the surface of the Greenland Ice Sheet has been documented from 1981 to present. We extend and refine this record using higher-resolution Moderate-Resolution Imaging Spectroradiometer (MODIS) data from March 2000 to the present. To permit changes to be observed over time, we are developing a well-characterized monthly climate-data record (CDR) of the "clear-sky" surface temperature of the Greenland Ice Sheet using data from both the Terra and Aqua satellites. We use the MODIS ice-surface temperature (IST) algorithm. Validation of the CDR consists of several facets: 1) comparisons between the Terra and Aqua IST maps; 2) comparisons between ISTs and in-situ measurements; 3) comparisons between ISTs and AWS data; and 4) comparisons of ISTs with surface temperatures derived from other satellite instruments such as the Thermal Emission and Reflection Radiometer. In this work, we focus on 1) and 2) above. Surface temperatures on the Greenland Ice Sheet have been studied on the ground, using automatic weather station (AWS) data from the Greenland-Climate Network (GC-Net), and from analysis of satellite sensor data. Using Advanced Very High Frequency Radiometer (AVHRR) weekly surface temperature maps, warming of the surface of the Greenland Ice Sheet has been documented from 1981 to present. We extend and refine this record using higher-resolution Moderate-Resolution Imaging Spectroradiometer (MODIS) data from March 2000 to the present. To permit changes to be observed over time, we are developing a well-characterized monthly climate-data record (CDR) of the "clear-sky" surface temperature of the Greenland Ice Sheet using data from both the Terra and Aqua satellites

  5. Effect of the Absorbed Photosynthetically Active Radiation Estimation Error on Net Primary Production Estimation - A Study with MODIS FPAR and TOMS Ultraviolet Reflective Products

    International Nuclear Information System (INIS)

    Absorbed photosynthetically active radiation (APAR), which is defined as downward solar radiation in 400-700 nm absorbed by vegetation, is one of the significant variables for Net Primary Production (NPP) estimation from satellite data. Toward the reduction of the uncertainties in the global NPP estimation, it is necessary to clarify the APAR accuracy. In this paper, first we proposed the improved PAR estimation method based on Eck and Dye's method in which the ultraviolet (UV) reflectivity data derived from Total Ozone Mapping Spectrometer (TOMS) at the top of atmosphere were used for clouds transmittance estimation. The proposed method considered the variable effects of land surface UV reflectivity on the satellite-observed UV data. Monthly mean PAR comparisons between satellite-derived and ground-based data at various meteorological stations in Japan indicated that the improved PAR estimation method reduced the bias errors in the summer season. Assuming the relative error of the fraction of PAR (FPAR) derived from Moderate Resolution Imaging Spectroradiometer (MODIS) to be 10%, we estimated APAR relative errors to be 10-15%. Annual NPP is calculated using APAR derived from MODIS/ FPAR and the improved PAR estimation method. It is shown that random and bias errors of annual NPP in a 1 km resolution pixel are less than 4% and 6% respectively. The APAR bias errors due to the PAR bias errors also affect the estimated total NPP. We estimated the most probable total annual NPP in Japan by subtracting the bias PAR errors. It amounts about 248 MtC/yr. Using the improved PAR estimation method, and Eck and Dye's method, total annual NPP is 4% and 9% difference from most probable value respectively. The previous intercomparison study among using fifteen NPP models4) showed that global NPP estimations among NPP models are 44.4-66.3 GtC/yr (coefficient of variation = 14%). Hence we conclude that the NPP estimation uncertainty due to APAR estimation error is small

  6. Mossin, Mody

    DEFF Research Database (Denmark)

    2005-01-01

    Katalog til udstillingen på KA d. 12. - 30. oktober 2005. Kataloget til udstillingen Mossin: Mody, til udstillingens fotografier og til det arkitektoniske udviklingsarbejde, som fotografierne dokumenterer igennem deres formidling af et særligt og kritisk syn på by og bygning.......Katalog til udstillingen på KA d. 12. - 30. oktober 2005. Kataloget til udstillingen Mossin: Mody, til udstillingens fotografier og til det arkitektoniske udviklingsarbejde, som fotografierne dokumenterer igennem deres formidling af et særligt og kritisk syn på by og bygning....

  7. A Technique for Remote Sensing of Suspended Sediments and Shallow Coastal Waters Using MODIS Visible and Near-IR Channels

    Science.gov (United States)

    Li, Rong-Rong; Kaufman, Yoram J.

    2002-01-01

    We have developed an algorithm to detect suspended sediments and shallow coastal waters using imaging data acquired with the Moderate Resolution Imaging SpectroRadiometer (MODIS). The MODIS instruments on board the NASA Terra and Aqua Spacecrafts are equipped with one set of narrow channels located in a wide 0.4 - 2.5 micron spectral range. These channels were designed primarily for remote sensing of the land surface and atmosphere. We have found that the set of land and cloud channels are also quite useful for remote sensing of the bright coastal waters. We have developed an empirical algorithm, which uses the narrow MODIS channels in this wide spectral range, for identifying areas with suspended sediments in turbid waters and shallow waters with bottom reflections. In our algorithm, we take advantage of the strong water absorption at wavelengths longer than 1 micron that does not allow illumination of sediments in the water or a shallow ocean floor. MODIS data acquired over the east coast of China, west coast of Africa, Arabian Sea, Mississippi Delta, and west coast of Florida are used in this study.

  8. Aqua Logistics Opens Office in China

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Aqua Logistics forays into the region with its subsidiary Aqua Logistics China Ltd. Aqua Logistics Ltd.,India-based full scope multi-national service provider,opened its subsidiary-Aqua Logistics China Ltd.(ALCL) in Beijing on October 23.

  9. An Approach for the Long-Term 30-m Land Surface Snow-Free Albedo Retrieval from Historic Landsat Surface Reflectance and MODIS-based A Priori Anisotropy Knowledge

    Science.gov (United States)

    Shuai, Yanmin; Masek, Jeffrey G.; Gao, Feng; Schaaf, Crystal B.; He, Tao

    2014-01-01

    Land surface albedo has been recognized by the Global Terrestrial Observing System (GTOS) as an essential climate variable crucial for accurate modeling and monitoring of the Earth's radiative budget. While global climate studies can leverage albedo datasets from MODIS, VIIRS, and other coarse-resolution sensors, many applications in heterogeneous environments can benefit from higher-resolution albedo products derived from Landsat. We previously developed a "MODIS-concurrent" approach for the 30-meter albedo estimation which relied on combining post-2000 Landsat data with MODIS Bidirectional Reflectance Distribution Function (BRDF) information. Here we present a "pre-MODIS era" approach to extend 30-m surface albedo generation in time back to the 1980s, through an a priori anisotropy Look-Up Table (LUT) built up from the high quality MCD43A BRDF estimates over representative homogenous regions. Each entry in the LUT reflects a unique combination of land cover, seasonality, terrain information, disturbance age and type, and Landsat optical spectral bands. An initial conceptual LUT was created for the Pacific Northwest (PNW) of the United States and provides BRDF shapes estimated from MODIS observations for undisturbed and disturbed surface types (including recovery trajectories of burned areas and non-fire disturbances). By accepting the assumption of a generally invariant BRDF shape for similar land surface structures as a priori information, spectral white-sky and black-sky albedos are derived through albedo-to-nadir reflectance ratios as a bridge between the Landsat and MODIS scale. A further narrow-to-broadband conversion based on radiative transfer simulations is adopted to produce broadband albedos at visible, near infrared, and shortwave regimes.We evaluate the accuracy of resultant Landsat albedo using available field measurements at forested AmeriFlux stations in the PNW region, and examine the consistency of the surface albedo generated by this approach

  10. NASA 3D Models: Aqua

    Data.gov (United States)

    National Aeronautics and Space Administration — Aqua, Latin for water, is a NASA Earth Science satellite mission named for the large amount of information that the mission is collecting about the Earth's water...

  11. NASA 3D Models: Aqua

    Data.gov (United States)

    National Aeronautics and Space Administration — Aqua carries six state-of-the-art instruments to observe the Earth's oceans, atmosphere, land, ice and snow covers, and vegetation, providing high measurement...

  12. MODIS/TERRA MOD11C3 Land Surface Temperature and Emissivity Monthly L3 Global 0.05Deg CMG Version 6

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The MODIS/Aqua Land Surface Temperature and Emissivity (LST/E) products provide per-pixel temperature and emissivity values in a sequence of swath-based global...

  13. MODIS/TERRA MYD11B2 Land Surface Temperature and Emissivity Daily L3 Global 5 km Grid SIN Version 6

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The MODIS/Aqua Land Surface Temperature and Emissivity (LST/E) products provide per-pixel temperature and emissivity values in a sequence of swath-based global...

  14. MODIS/TERRA MOD11C2 Land Surface Temperature/Emissivity 8-Day L3 Global 0.05Deg CMG Version 6

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The MODIS/Aqua Land Surface Temperature and Emissivity (LST/E) products provide per-pixel temperature and emissivity values in a sequence of swath-based global...

  15. MODIS/TERRA MOD11B3 Land Surface Temperature and Emissivity Daily L3 Global 5 km Grid SIN Version 6

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The MODIS/Aqua Land Surface Temperature and Emissivity (LST/E) products provide per-pixel temperature and emissivity values in a sequence of swath-based global...

  16. MODIS/TERRA MYD11B3 Land Surface Temperature and Emissivity Daily L3 Global 5 km Grid SIN Version 6

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The MODIS/Aqua Land Surface Temperature and Emissivity (LST/E) products provide per-pixel temperature and emissivity values in a sequence of swath-based global...

  17. MODIS/TERRA MOD11B1 Land Surface Temperature and Emissivity Daily L3 Global 5 km Grid SIN Version 6

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The MODIS/Aqua Land Surface Temperature and Emissivity (LST/E) products provide per-pixel temperature and emissivity values in a sequence of swath-based global...

  18. MODIS/TERRA MOD11B2 Land Surface Temperature and Emissivity Daily L3 Global 5 km Grid SIN Version 6

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The MODIS/Aqua Land Surface Temperature and Emissivity (LST/E) products provide per-pixel temperature and emissivity values in a sequence of swath-based global...

  19. MODIS/COMBINED MOD11A1 Land Surface Temperature and Emissivity Daily L3 Global 1 km Grid SIN Version 6

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The MODIS/Aqua Land Surface Temperature and Emissivity (LST/E) products provide per-pixel temperature and emissivity values in a sequence of swath-based global...

  20. MODIS/TERRA MOD11_L2 Land Surface Temperature and Emissivity 5-Minute L2 Swath 1 km Version 6

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The MODIS/Aqua Land Surface Temperature and Emissivity (LST/E) products provide per-pixel temperature and emissivity values in a sequence of swath-based global...

  1. MODIS/TERRA MOD11C1 Land Surface Temperature and Emissivity Daily L3 Global 0.05Deg CMG Version 6

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The MODIS/Aqua Land Surface Temperature and Emissivity (LST/E) products provide per-pixel temperature and emissivity values in a sequence of swath-based global...

  2. Evaluation and Intercomparison of MODIS and GEOV1 Global Leaf Area Index Products over Four Sites in North China

    OpenAIRE

    Zhenwang Li; Huan Tang; Baohui Zhang; Guixia Yang; Xiaoping Xin

    2015-01-01

    This study investigated the performances of the Moderate Resolution Imaging Spectroradiometer (MODIS) and GEOLAND2 Version 1 (GEOV1) Leaf Area Index (LAI) products using ground measurements and LAI reference maps over four sites in North China for 2011–2013. The Terra + Aqua MODIS and Terra MODIS LAI retrieved by the main algorithm and GEOV1 LAI within the valid range were evaluated and intercompared using LAI reference maps to assess their uncertainty and seasonal variability The results sho...

  3. Chlorophyll increases off the coasts of Japan after the 2011 tsunami using NASA/MODIS data

    OpenAIRE

    E. Sava; Edwards, B; Cervone, G.

    2014-01-01

    Large chlorophyll anomalies are observed after the 2011 Japanese tsunami using the NASA MODIS instrument onboard the TERRA and AQUA satellites. These anomalies are observed both along the eastern coast of Japan, where the tsunami wave hit with maximum force, and in the deep water surrounding the epicentral region. Although both satellites show agreeing spatio-temporal patterns, larger anomalies are detected using the AQUA satellite. A temporal analysis shows increased chloro...

  4. Chlorophyll increases off the coasts of Japan after the 2011 Tsunami using NASA/MODIS data

    OpenAIRE

    E. Sava; Edwards, B; Cervone, G.

    2013-01-01

    Large chlorophyll anomalies are observed after the 2011 Japanese tsunami using the NASA MODIS instrument onboard the TERRA and AQUA satellites. These anomalies are observed both along the Eastern coast of Japan, where the tsunami wave hit with maximum force, and in the deep water surrounding the epicentral region. Although both satellites show agreeing spatio-temporal patterns, larger anomalies are detected using the AQUA satellite. A temporal analysis shows increased chloro...

  5. MODIS Data from the GES DISC DAAC: Moderate-Resolution Imaging Spectroradiometer (MODIS)

    Science.gov (United States)

    2002-01-01

    The Goddard Earth Sciences (GES) Distributed Active Archive Center (DAAC) is responsible for the distribution of the Level 1 data, and the higher levels of all Ocean and Atmosphere products (Land products are distributed through the Land Processes (LP) DAAC DAAC, and the Snow and Ice products are distributed though the National Snow and Ice Data Center (NSIDC) DAAC). Ocean products include sea surface temperature (SST), concentrations of chlorophyll, pigment and coccolithophores, fluorescence, absorptions, and primary productivity. Atmosphere products include aerosols, atmospheric water vapor, clouds and cloud masks, and atmospheric profiles from 20 layers. While most MODIS data products are archived in the Hierarchical Data Format-Earth Observing System (HDF-EOS 2.7) format, the ocean binned products and primary productivity products (Level 4) are in the native HDF4 format. MODIS Level 1 and 2 data are of the Swath type and are packaged in files representing five minutes of Files for Level 3 and 4 are global products at daily, weekly, monthly or yearly resolutions. Apart from the ocean binned and Level 4 products, these are in Grid type, and the maps are in the Cylindrical Equidistant projection with rectangular grid. Terra viewing (scenes of approximately 2000 by 2330 km). MODIS data have several levels of maturity. Most products are released with a provisional level of maturity and only announced as validated after rigorous testing by the MODIS Science Teams. MODIS/Terra Level 1, and all MODIS/Terra 11 micron SST products are announced as validated. At the time of this publication, the MODIS Data Support Team (MDST) is working with the Ocean Science Team toward announcing the validated status of the remainder of MODIS/Terra Ocean products. MODIS/Aqua Level 1 and cloud mask products are released with provisional maturity.

  6. EOS Aqua Mission Status at Earth Science Constellation MOWG Meeting @ LASP April 13, 2016

    Science.gov (United States)

    Guit, William J.

    2016-01-01

    This presentation reflects the EOS Aqua mission status, spacecraft subsystem summary, recent and planned activities, inclination adjust maneuvers, propellant usage and lifetime estimate, orbital maintenance maneuvers, conjunction assessment high interest events, ground track error, spacecraft orbital parameters trends and predictions.

  7. Towards a long-term global aerosol optical depth record: applying a consistent aerosol retrieval algorithm to MODIS and VIIRS-observed reflectance

    Directory of Open Access Journals (Sweden)

    R. C. Levy

    2015-07-01

    Full Text Available To answer fundamental questions about aerosols in our changing climate, we must quantify both the current state of aerosols and how they are changing. Although NASA's Moderate resolution Imaging Spectroradiometer (MODIS sensors have provided quantitative information about global aerosol optical depth (AOD for more than a decade, this period is still too short to create an aerosol climate data record (CDR. The Visible Infrared Imaging Radiometer Suite (VIIRS was launched on the Suomi-NPP satellite in late 2011, with additional copies planned for future satellites. Can the MODIS aerosol data record be continued with VIIRS to create a consistent CDR? When compared to ground-based AERONET data, the VIIRS Environmental Data Record (V_EDR has similar validation statistics as the MODIS Collection 6 (M_C6 product. However, the V_EDR and M_C6 are offset in regards to global AOD magnitudes, and tend to provide different maps of 0.55 μm AOD and 0.55/0.86 μm-based Ångstrom Exponent (AE. One reason is that the retrieval algorithms are different. Using the Intermediate File Format (IFF for both MODIS and VIIRS data, we have tested whether we can apply a single MODIS-like (ML dark-target algorithm on both sensors that leads to product convergence. Except for catering the radiative transfer and aerosol lookup tables to each sensor's specific wavelength bands, the ML algorithm is the same for both. We run the ML algorithm on both sensors between March 2012 and May 2014, and compare monthly mean AOD time series with each other and with M_C6 and V_EDR products. Focusing on the March–April–May (MAM 2013 period, we compared additional statistics that include global and gridded 1° × 1° AOD and AE, histograms, sampling frequencies, and collocations with ground-based AERONET. Over land, use of the ML algorithm clearly reduces the differences between the MODIS and VIIRS-based AOD. However, although global offsets are near zero, some regional biases remain

  8. Validation of MODIS Aerosol Optical Depth Retrievals over a Tropical Urban Site, Pune, India

    Science.gov (United States)

    More, Sanjay; Kuman, P. Pradeep; Gupta, Pawan; Devara, P. C. S.; Aher, G. R.

    2011-01-01

    In the present paper, MODIS (Terra and Aqua; level 2, collection 5) derived aerosoloptical depths (AODs) are compared with the ground-based measurements obtained from AERONET (level 2.0) and Microtops - II sun-photometer over a tropical urban station, Pune (18 deg 32'N; 73 deg 49'E, 559 m amsl). This is the first ever systematic validation of the MODIS aerosol products over Pune. Analysis of the data indicates that the Terra and Aqua MODIS AOD retrievals at 550 nm have good correlations with the AERONET and Microtops - II sun-photometer AOD measurements. During winter the linear regression correlation coefficients for MODIS products against AERONET measurements are 0.79 for Terra and 0.62 for Aqua; however for premonsoon, the corresponding coefficients are 0.78 and 0.74. Similarly, the linear regression correlation coefficients for Microtops measurements against MODIS products are 0.72 and 0.93 for Terra and Aqua data respectively during winter and are 0.78 and 0.75 during pre-monsoon. On yearly basis in 2008-2009, correlation coefficients for MODIS products against AERONET measurements are 0.80 and 0.78 for Terra and Aqua respectively while the corresponding coefficients are 0.70 and 0.73 during 2009-2010. The regressed intercepts with MODIS vs. AERONET are 0.09 for Terra and 0.05 for Aqua during winter whereas their values are 0.04 and 0.07 during pre-monsoon. However, MODIS AODs are found to underestimate during winter and overestimate during pre-monsoon with respect to AERONET and Microtops measurements having slopes 0.63 (Terra) and 0.74 (Aqua) during winter and 0.97 (Terra) and 0.94 (Aqua) during pre-monsoon. Wavelength dependency of Single Scattering Albedo (SSA) shows presence of absorbing and scattering aerosol particles. For winter, SSA decreases with wavelength with the values 0.86 +/- 0.03 at 440 nm and 0.82 +/- 0.04 at 1020nm. In pre-monsoon, it increases with wavelength (SSA is 0.87 +/- 0.02 at 440nm; and 0.88 +/-0.04 at 1020 nm).

  9. A SOAP Web Service for accessing MODIS land product subsets

    Energy Technology Data Exchange (ETDEWEB)

    SanthanaVannan, Suresh K [ORNL; Cook, Robert B [ORNL; Pan, Jerry Yun [ORNL; Wilson, Bruce E [ORNL

    2011-01-01

    Remote sensing data from satellites have provided valuable information on the state of the earth for several decades. Since March 2000, the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor on board NASA s Terra and Aqua satellites have been providing estimates of several land parameters useful in understanding earth system processes at global, continental, and regional scales. However, the HDF-EOS file format, specialized software needed to process the HDF-EOS files, data volume, and the high spatial and temporal resolution of MODIS data make it difficult for users wanting to extract small but valuable amounts of information from the MODIS record. To overcome this usability issue, the NASA-funded Distributed Active Archive Center (DAAC) for Biogeochemical Dynamics at Oak Ridge National Laboratory (ORNL) developed a Web service that provides subsets of MODIS land products using Simple Object Access Protocol (SOAP). The ORNL DAAC MODIS subsetting Web service is a unique way of serving satellite data that exploits a fairly established and popular Internet protocol to allow users access to massive amounts of remote sensing data. The Web service provides MODIS land product subsets up to 201 x 201 km in a non-proprietary comma delimited text file format. Users can programmatically query the Web service to extract MODIS land parameters for real time data integration into models, decision support tools or connect to workflow software. Information regarding the MODIS SOAP subsetting Web service is available on the World Wide Web (WWW) at http://daac.ornl.gov/modiswebservice.

  10. Modular district heating system MODiS

    Energy Technology Data Exchange (ETDEWEB)

    Sipilae, K.; Ranne, A.; Koljonen, T. [VTT Energy, Espoo (Finland). Energy Systems

    2000-12-01

    MODiS (Modular District Heating System) products were developed for either building an entirely new district heating (DH) system or for renovating and extending an existing system. MODiS products comprise highly integrated prefabricated and pre- tested modules, where the modules themselves may be boilers, pumping stations, substations, metering devices, automation equipment, planning tools, information and management systems. The MODiS Concept tool was developed by VTT Energy for the rough planning of a MODiS district heating system. As a result, the MODiS Concept model can give the budget for a DH-system divided into the boiler plant, the district heating pipelines and the consumer substations. The annual investment and running cost of the system are evaluated. A dynamic simulation model for MODiS was also created with a real time simulation tool called APROS. The simulator can be used for studying normal operation, behaviour under emergency conditions, and process failures. The APROS simulation program has also been used to investigate an ejector connection in an apartment building and for analysing the operation of the ejector in relation to the entire heating system. A DH system in a Russian district heating zone was modelled with the programs. A knowledge-based tool, PIPECOR, has been developed and it estimates the remaining service life of the pipelines under the defined conditions, and the current corrosion rate. Renovation principles for the East European district heating systems have been developed during the project. (orig.)

  11. Validation of MODIS 3 km Resolution Aerosol Optical Depth Retrievals Over Asia

    Directory of Open Access Journals (Sweden)

    Janet E. Nichol

    2016-04-01

    Full Text Available This study evaluates the new Aqua MODIS Dark Target (DT Collection 6 (C6 Aerosol Optical Depth (AOD (MYD04_3K retrieval algorithm at 3 km resolution over Asian countries that have recently experienced severe and increasing air pollution. Retrievals showed generally low accuracy compared with the AErosol RObotic NETwork (AERONET, with only 55% of retrievals within the expected error (EE. The uncertainty appears mainly due to systematic overestimation at both low and high AOD levels. This is attributed to under-prediction of surface reflectance, similar to, but more severe than, the C6 DT product at 10-km resolution. This is because MYD04_3K observes more noise in the surface reflectance computations, due to retention of some bright pixels in the retrieval window which would be discarded at 10 km. Greatest uncertainty was observed at urban sites, especially those dominated by coarse aerosols. Results suggest that the DT at 3 km is less reliable than MODIS C6 AOD products at 10 km.

  12. Linking glacier annual mass balance and glacier albedo retrieved from MODIS data

    Directory of Open Access Journals (Sweden)

    M. Dumont

    2012-07-01

    Full Text Available Albedo is one of the variables controlling the mass balance of temperate glaciers. Multispectral imagers, such as MODerate Imaging Spectroradiometer (MODIS on board the TERRA and AQUA satellites, provide a means to monitor glacier surface albedo. In this study, different methods to retrieve broadband glacier surface albedo from MODIS data are compared. The effect of multiple reflections due to the rugged topography and of the anisotropic reflection of snow and ice are particularly investigated. The methods are tested on the Saint Sorlin Glacier (Grandes Rousses area, French Alps. The accuracy of the retrieved albedo is estimated using both field measurements, at two automatic weather stations located on the glacier, and albedo values derived from terrestrial photographs. For summers 2008 and 2009, the Root Mean Square Deviation (RMSD between field measurements and the broadband albedo retrieved from MODIS data at 250 m spatial resolution was found to be 0.052 or about 10% relative error. The RMSD estimated for the MOD10 daily albedo product is about three times higher. One decade (2000–2009 of MODIS data were then processed to create a time series of albedo maps of Saint Sorlin Glacier during the ablation season. The annual mass balance of Saint Sorlin Glacier was compared with the minimum albedo value (average over the whole glacier surface observed with MODIS during the ablation season. A strong linear correlation exists between the two variables. Furthermore, the date when the average albedo of the whole glacier reaches a minimum closely corresponds to the period when the snowline is located at its highest elevation, thus when the snowline is a good indicator of the glacier equilibrium line. This indicates that this strong correlation results from the fact that the minimal average albedo values of the glacier contains a considerable information regarding the relative share of areal surfaces between the ablation zone (i.e. ice with generally

  13. Global land surface albedo maps from MODIS using the Google Earth Engine

    Science.gov (United States)

    Mitraka, Zina; Benas, Nikolaos; Gorelick, Noel; Chrysoulakis, Nektarios

    2016-04-01

    The land surface albedo (LSA) is a critical physical variable, which influences the Earth's climate by affecting the energy budget and distribution in the Earth-atmosphere system. Its role is highly significant in both global and local scales; hence, LSA measurements provide a quantitative means for better constraining global and regional scale climate modelling efforts. The Moderate Resolution Imaging Spectroradiometer (MODIS) sensor, on board NASA's Terra and Aqua platforms, provides the parameters needed for the computation of LSA on an 8-day temporal scale and a variety of spatial scales (ranging between 0.5 - 5 km). This dataset was used here for the LSA estimation and its changes over the study area at 0.5 km spatial resolution. More specifically, the MODIS albedo product was used, which includes both the directional-hemispherical surface reflectance (black-sky albedo) and the bi-hemispherical surface reflectance (white-sky albedo). The LSA was estimated for the whole globe on an 8-day basis for the whole time period covered by MODIS acquisitions (i.e. 2000 until today). To estimate LSA from black-sky and white-sky albedos, the fraction of the diffused radiation is needed, a function of the Aerosol Optical Thickness (AOT). Required AOT information was acquired from the MODIS AOT product at 1̊ × 1̊ spatial resolution. Since LSA also depends on solar zenith angle (SZA), 8-day mean LSA values were computed as averages of corresponding LSA values for representative SZAs covering the 24-hour day. The estimated LSA was analysed in terms of both spatial and seasonal characteristics, while LSA changes during the period examined were assessed. All computation were performed using the Google Earth Engine (GEE). The GEE provided access to all the MODIS products needed for the analysis without the need of searching or downloading. Moreover, the combination of MODIS products in both temporal and spatial terms was fast and effecting using the GEE API (Application

  14. Evaluating the assumptions of surface reflectance and aerosol type selection within the MODIS aerosol retrieval over land: The problem of dust type selection

    NARCIS (Netherlands)

    Mielonen, T.; Levy, R.C.; Aaltonen, V.; Komppula, M.; Leeuw, G. de; Huttunen, J.; Lihavainen, H.; Kolmonen, P.; Lehtinen, K.E.J.; Arola, A.

    2011-01-01

    Aerosol Optical Depth (AOD) and Ångström exponent (AE) values derived with the MODIS retrieval algorithm over land (Collection 5) are compared with ground based sun photometer measurements at eleven sites spanning the globe. Although, in general, total AOD compares well at these sites (R 2 values ge

  15. Cloudiness and snow cover in Alpine areas from MODIS products

    OpenAIRE

    P. Da Ronco; De Michele, C.

    2014-01-01

    Snow cover maps provide an information of great practical interest for hydrologic purposes: when combined with point values of snow water equivalent (SWE), they allow to estimate the regional snow resource. Earth observation satellites are an interesting tool for evaluating large scale snow distribution and extension. In this context, MODIS (MODerate resolution Imaging Spectroradiometeron on board Terra and Aqua satellites) daily Snow Covered Area product has been widely tes...

  16. Detecting Forest Disturbance in the Pacific Northwest From MODIS Time Series Using Temporal Segmentation

    Science.gov (United States)

    Sulla-Menashe, D. J.; Yang, Z.; Braaten, J.; Krankina, O. N.; Kennedy, R. E.; Friedl, M. A.

    2011-12-01

    Changes to the land surface of the Earth are occurring at unprecedented rates with significant implications for surface energy balance and regional to global scale cycles of carbon and water. Data from the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard the Aqua and Terra satellite platforms provide over 11 years of consistent, synoptic observations of the biosphere. New methods have recently emerged to analyze time series of remote sensing images, thereby providing ecologically important information about disturbance and succession over large regions. In particular, the Landtrendr algorithm was developed to characterize long-term trends, including punctual and gradual disturbance events and subsequent vegetation regrowth, in dense time series of Landsat imagery. While this approach has shown to be useful and robust in a wide range of ecosystems, its application is limited to areas with sufficient Landsat archive depth and relatively cloud-free periods. Additionally, the approach requires significant effort in atmospheric correction and normalization steps, increasing the cost for large-area application. Here we present an adaptation of the Landtrendr algorithm to an 11-year time series of MODIS Normalized BRDF-Adjusted Reflectance (NBAR) data to detect forest disturbance in the Northwest Forest Plan (NWFP) area of Washington, Oregon, and California. The NWFP area represents a dynamic zone of forest management with an active disturbance regime that includes insect defoliation, wildfires, and logging. This work aims to explore how the size and severity of disturbance events influence detection and characterization of such events using MODIS data. We sampled disturbance events across gradients of size and severity that occurred during the MODIS era (2000-present) using a high-quality database of forest disturbance information derived from Landsat. One-third of these disturbance records were used to calibrate the model using MODIS NBAR time series, and

  17. Uso de imagens MODIS no monitoramento do fluxo de sedimentos no reservatório de Três Marias

    OpenAIRE

    Carlos E. T. Pinto; Paulo H. B. J. Menezes; Jean-Michel Martinez; Henrique L. Roig; Raúl A. E. Villar

    2014-01-01

    Objetivou-se, neste trabalho, monitorar o fluxo de entrada de sedimentos no braço do Rio Indaiá no reservatório de Três Marias, MG, com base em dados das imagens de satélites. Foram adquiridas séries temporais de 12 anos das imagens MODIS (Terra e Aqua), compostas de 8 dias. Estimativas de reflectância da superfície foram calculadas usando-se o algoritmo MOD3R. Dados hidrossedimentométricos da estação de monitoramento do Rio Indaiá foram integrados às análises para se entender a relação entre...

  18. The Plane-parallel Albedo Bias of Liquid Clouds from MODIS Observations

    Science.gov (United States)

    Oreopoulos, Lazaros; Cahalan, Robert F.; Platnick, Steven

    2007-01-01

    In our most advanced modeling tools for climate change prediction, namely General Circulation Models (GCMs), the schemes used to calculate the budget of solar and thermal radiation commonly assume that clouds are horizontally homogeneous at scales as large as a few hundred kilometers. However, this assumption, used for convenience, computational speed, and lack of knowledge on cloud small scale variability, leads to erroneous estimates of the radiation budget. This paper provides a global picture of the solar radiation errors at scales of approximately 100 km due to warm (liquid phase) clouds only. To achieve this, we use cloud retrievals from the instrument MODIS on the Terra and Aqua satellites, along with atmospheric and surface information, as input into a GCM-style radiative transfer algorithm. Since the MODIS product contains information on cloud variability below 100 km we can run the radiation algorithm both for the variable and the (assumed) homogeneous clouds. The difference between these calculations for reflected or transmitted solar radiation constitutes the bias that GCMs would commit if they were able to perfectly predict the properties of warm clouds, but then assumed they were homogeneous for radiation calculations. We find that the global average of this bias is approx.2-3 times larger in terms of energy than the additional amount of thermal energy that would be trapped if we were to double carbon dioxide from current concentrations. We should therefore make a greater effort to predict horizontal cloud variability in GCMs and account for its effects in radiation calculations.

  19. Detection and monitoring of two dust storm events by multispectral modis images.

    Digital Repository Service at National Institute of Oceanography (India)

    Mehta P.S.; Kunte, P.D.

    of Oman, over Arabian Sea to the coast of Pakistan. The dust storm lasted over the Arabian Sea till 30th March. MODIS sensors on both Terra and Aqua Satellites captured images of both events. From the difference in emissive/transmissive nature...

  20. Cloud-type dependencies of MODIS and AMSR-E liquid water path differences

    OpenAIRE

    Torre Juárez, M.; B. H. Kahn; E. J. Fetzer

    2009-01-01

    Comparisons of cloud liquid water path (LWP) retrievals are presented from the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Advanced Microwave Scanning Radiometer (AMSR-E) located aboard the Aqua spacecraft. LWP differences as a function of cloud top height, cloud fraction, cloud top temperature, LWP, cloud effective radius and cloud optical thickness are quantified in most geophysical conditions. The assumption of vertica...

  1. NLCD - MODIS albedo data

    Data.gov (United States)

    U.S. Environmental Protection Agency — The NLCD-MODIS land cover-albedo database integrates high-quality MODIS albedo observations with areas of homogeneous land cover from NLCD. The spatial resolution...

  2. Mapping the Distribution of Cloud Forests Using MODIS Imagery

    Science.gov (United States)

    Douglas, M. W.; Mejia, J.; Murillo, J.; Orozco, R.

    2007-05-01

    Tropical cloud forests - those forests that are frequently immersed in clouds or otherwise very humid, are extremely difficult to map from the ground, and are not easily distinguished in satellite imagery from other forest types, but they have a very different flora and fauna than lowland rainforest. Cloud forests, although found in many parts of the tropics, have a very restricted vertical extent and thus are also restricted horizontally. As a result, they are subject to both human disturbance (coffee growing for example) and the effects of possible climate change. Motivated by a desire to seek meteorological explanations for the distribution of cloud forests, we have begun to map cloudiness using MODIS Terra and Aqua visible imagery. This imagery, at ~1030 LT and 1330 LT, is an approximation for mid-day cloudiness. In tropical regions the amount of mid-day cloudiness strongly controls the shortwave radiation and thus the potential for evaporation (and aridity). We have mapped cloudiness using a simple algorithm that distinguishes between the cloud-free background brightness and the generally more reflective clouds to separate clouds from the underlying background. A major advantage of MODIS imagery over many other sources of satellite imagery is its high spatial resolution (~250m). This, coupled with precisely navigated images, means that detailed maps of cloudiness can be produced. The cloudiness maps can then be related to the underlying topography to further refine the location of the cloud forests. An advantage of this technique is that we are mapping the potential cloud forest, based on cloudiness, rather than the actual cloud forest, which are commonly based on forest estimates from satellite and digital elevation data. We do not derive precipitation, only estimates of daytime cloudiness. Although only a few years of MODIS imagery has been used in our studies, we will show that this is sufficient to describe the climatology of cloudiness with acceptable

  3. Sea Ice Surface Temperature Product from the Moderate Resolution Imaging Spectroradiometer (MODIS)

    Science.gov (United States)

    Hall, Dorothy K.; Key, Jeffrey R.; Casey, Kimberly A.; Riggs, George A.; Cavalieri, Donald J.

    2003-01-01

    Global sea ice products are produced from the Earth Observing System (EOS) Moderate Resolution Imaging Spectroradiometer (MODIS) on board both the Terra and Aqua satellites. Daily sea ice extent and ice-surface temperature (IST) products are available at 1- and 4-km resolution. Validation activities have been undertaken to assess the accuracy of the MODIS IST product at the South Pole station in Antarctica and in the Arctic Ocean using near-surface air-temperature data from a meteorological station and drifting buoys. Results from the study areas show that under clear skies, the MODIS ISTs are very close to those of the near-surface air temperatures with a bias of -1.1 and -1.2 K, and an uncertainty of 1.6 and 1.7 K, respectively. It is shown that the uncertainties would be reduced if the actual temperature of the ice surface were reported instead of the near-surface air temperature. It is not possible to get an accurate IST from MODIS in the presence of even very thin clouds or fog, however using both the Advanced Microwave Scanning Radiometer-EOS (AMSR-E) and the MODIS on the Aqua satellite, it may be possible to develop a relationship between MODIS-derived IST and ice temperature derived from the AMSR-E. Since the AMSR-E measurements are generally unaffected by cloud cover, they may be used to complement the MODIS IST measurements.

  4. MONTHLY VARIABILITY OF TOTAL SUSPENDED MATTER (TSM MAPPING USING MODIS 250M TO SUPPORT MARINE CULTURE AT MOROTAI ISLAND, NORTH MALUKU

    Directory of Open Access Journals (Sweden)

    KOMANG IWAN SUNIADA

    2015-05-01

    Full Text Available This study was conducted to provide an information of Total Suspended Matter concentration and its monthly variability using dialy data of Terra/ Aqua MOD IS level 1 b with spatial resolution 250m imagery at Morotai Island, Northern Maluku. TSM is one of the water quality key parameter to support finding suitable area which is an important step for marine culture activity. Dialy Aqua/Terra MODIS level lb, 250m dataset was downloaded freely from Goddard Space Flight Center, LAADS Web (http ://ladsweb.nascom.nasa.gov/ and its contains information of calibrated radiance dan reflectance. TSM concentration derived using algorithm proposed by Trisakti et al, TSM (mg/I = 72743 (bl+b22 ·3551, where bl is remote sensing reflectance band 1 and b2 is remote sensing reflectance band 2. Further process is daily TSM data composited to produce monthly data to define the variability. GIS application technique based on apropriate environment condition for fish comodity are used to mapping suitable area concerning of TSM parameter. Suspended sediment concentrations derived from satellite data showed that the average range of 40-90 mg/I, with the highest suspended sediment concentration occurred in January and lowest in June

  5. Landsat and MODIS Fusion for Disturbance Analysis in New Zealand

    Science.gov (United States)

    Owsley, B.; de Beurs, K.; Julian, J.

    2013-12-01

    Land management is a key driver of land change in many parts of the world. Activities such as livestock farming and timber production can have a dramatic impact on the environment and are often guided by local and regional policies. Evaluation of these impacts is particularly important in a country like New Zealand, where since 1991 political boundaries have largely coincided with environmental boundaries (catchments). In this study we look at the entire north island of New Zealand and identify disturbance trends at high spatial and temporal resolution using widely available remote sensing data, with the eventual goal of analyzing the effect of land management practices on local ecosystems. Existing remote sensing capabilities are limited in the type of analysis they allow. Free access to the entire Landsat archive provides a valuable resource for analyzing land change across large areas and extended time periods. Landsat images, at 30m spatial resolution, provide a useful tool for monitoring small changes in land cover; however, the 16-day temporal cycle, which is often lengthened considerably by cloud cover, limits the observation of short term changes that can result from disturbance events. The revisit cycle of the MODIS sensors aboard Terra and Aqua provides a surface reflectance dataset at much higher temporal resolution, yet at 500m spatial resolution, it lacks the detail necessary to accurately track small changes in the landscape. A combination of the two products offers researchers the ideal tool for disturbance analysis. Here we utilize both Landsat TM/ETM surface reflectance data and MODIS Nadir BRDF-adjusted reflectance (NBAR) covering the north island of New Zealand (13 Landsat path/rows) for the period 2000-2012. We calculate a disturbance index for both datasets based on normalized values of the Tasseled Cap transformation and then create a fused 8-day, 30m disturbance time series. We then investigate the time series to assess the subtle changes in

  6. Frequency and causes of failed MODIS cloud property retrievals for liquid phase clouds over global oceans

    Science.gov (United States)

    Cho, Hyoun‐Myoung; Meyer, Kerry; Lebsock, Matthew; Platnick, Steven; Ackerman, Andrew S.; Di Girolamo, Larry; C.‐Labonnote, Laurent; Cornet, Céline; Riedi, Jerome; Holz, Robert E.

    2015-01-01

    Abstract Moderate Resolution Imaging Spectroradiometer (MODIS) retrieves cloud droplet effective radius (r e) and optical thickness (τ) by projecting observed cloud reflectances onto a precomputed look‐up table (LUT). When observations fall outside of the LUT, the retrieval is considered “failed” because no combination of τ and r e within the LUT can explain the observed cloud reflectances. In this study, the frequency and potential causes of failed MODIS retrievals for marine liquid phase (MLP) clouds are analyzed based on 1 year of Aqua MODIS Collection 6 products and collocated CALIOP and CloudSat observations. The retrieval based on the 0.86 µm and 2.1 µm MODIS channel combination has an overall failure rate of about 16% (10% for the 0.86 µm and 3.7 µm combination). The failure rates are lower over stratocumulus regimes and higher over the broken trade wind cumulus regimes. The leading type of failure is the “r e too large” failure accounting for 60%–85% of all failed retrievals. The rest is mostly due to the “r e too small” or τ retrieval failures. Enhanced retrieval failure rates are found when MLP cloud pixels are partially cloudy or have high subpixel inhomogeneity, are located at special Sun‐satellite viewing geometries such as sunglint, large viewing or solar zenith angles, or cloudbow and glory angles, or are subject to cloud masking, cloud overlapping, and/or cloud phase retrieval issues. The majority (more than 84%) of failed retrievals along the CALIPSO track can be attributed to at least one or more of these potential reasons. The collocated CloudSat radar reflectivity observations reveal that the remaining failed retrievals are often precipitating. It remains an open question whether the extremely large r e values observed in these clouds are the consequence of true cloud microphysics or still due to artifacts not included in this study.

  7. An analysis of the collection 5 MODIS over-ocean aerosol optical depth product for its implication in aerosol assimilation

    OpenAIRE

    Shi, Y; Zhang, J.; Reid, J. S.; B. Holben; Hyer, E. J.; C. Curtis

    2011-01-01

    As an update to our previous use of the collection 4 Moderate Resolution Imaging Spectroradiometer (MODIS) over-ocean aerosol optical depth (AOD) data, we examined ten years of Terra and eight years of Aqua collection 5 data for its potential usage in aerosol assimilation. Uncertainties in the over-ocean MODIS AOD were studied as functions of observing conditions, such as surface characteristics, aerosol optical properties, and cloud artifacts. Empirical corrections and quality assurance proc...

  8. An analysis of the Collection 5 MODIS over-ocean aerosol optical depth product for its implication in aerosol assimilation

    OpenAIRE

    Shi, Y; J. Zhang; Reid, J. S.; B. Holben; Hyer, E. J.; C. Curtis

    2010-01-01

    As an update to our previous use of the Collection 4 Moderate Resolution Imaging Spectroradiometer (MODIS) over-water aerosol optical depth (AOD, symbol as τ data, we examined ten years of Terra and eight years of Aqua data Collection 5 data for its potential usage in aerosol data assimilation. Uncertainties in the over-water MODIS AOD were studied as functions of observing conditions, such as surface characteristics, aerosol optical properties, and cloud artifacts. Empirical corrections and ...

  9. A snow cover climatology for the Pyrenees from MODIS snow products

    Science.gov (United States)

    Gascoin, S.; Hagolle, O.; Huc, M.; Jarlan, L.; Dejoux, J.-F.; Szczypta, C.; Marti, R.; Sanchez, R.

    2015-05-01

    The seasonal snow in the Pyrenees is critical for hydropower production, crop irrigation and tourism in France, Spain and Andorra. Complementary to in situ observations, satellite remote sensing is useful to monitor the effect of climate on the snow dynamics. The MODIS daily snow products (Terra/MOD10A1 and Aqua/MYD10A1) are widely used to generate snow cover climatologies, yet it is preferable to assess their accuracies prior to their use. Here, we use both in situ snow observations and remote sensing data to evaluate the MODIS snow products in the Pyrenees. First, we compare the MODIS products to in situ snow depth (SD) and snow water equivalent (SWE) measurements. We estimate the values of the SWE and SD best detection thresholds to 40 mm water equivalent (w.e.) and 150 mm, respectively, for both MOD10A1 and MYD10A1. κ coefficients are within 0.74 and 0.92 depending on the product and the variable for these thresholds. However, we also find a seasonal trend in the optimal SWE and SD thresholds, reflecting the hysteresis in the relationship between the depth of the snowpack (or SWE) and its extent within a MODIS pixel. Then, a set of Landsat images is used to validate MOD10A1 and MYD10A1 for 157 dates between 2002 and 2010. The resulting accuracies are 97% (κ = 0.85) for MOD10A1 and 96% (κ = 0.81) for MYD10A1, which indicates a good agreement between both data sets. The effect of vegetation on the results is analyzed by filtering the forested areas using a land cover map. As expected, the accuracies decrease over the forests but the agreement remains acceptable (MOD10A1: 96%, κ = 0.77; MYD10A1: 95%, κ = 0.67). We conclude that MODIS snow products have a sufficient accuracy for hydroclimate studies at the scale of the Pyrenees range. Using a gap-filling algorithm we generate a consistent snow cover climatology, which allows us to compute the mean monthly snow cover duration per elevation band and aspect classes. There is snow on the ground at least 50% of the

  10. Irrigation modeling with AquaCrop

    Science.gov (United States)

    AquaCrop is a crop water productivity model developed by the Land and Water Division of UN-FAO. It simulates yield response to water of herbaceous crops, and is suited to address conditions where water is a key limiting factor in crop production. AquaCrop attempts to balance accuracy, simplicity, an...

  11. An analysis of the collection 5 MODIS over-ocean aerosol optical depth product for its implication in aerosol assimilation

    Directory of Open Access Journals (Sweden)

    Y. Shi

    2011-01-01

    Full Text Available As an update to our previous use of the collection 4 Moderate Resolution Imaging Spectroradiometer (MODIS over-ocean aerosol optical depth (AOD data, we examined ten years of Terra and eight years of Aqua collection 5 data for its potential usage in aerosol assimilation. Uncertainties in the over-ocean MODIS AOD were studied as functions of observing conditions, such as surface characteristics, aerosol optical properties, and cloud artifacts. Empirical corrections and quality assurance procedures were developed and compared to collection 4 data. After applying these procedures, the Root-Mean-Square-Error (RMSE in the MODIS Terra and Aqua AOD are reduced by 30% and 10–20%, respectively, with respect to AERONET data. Ten years of Terra and eight years of Aqua quality-assured level 3 MODIS over-ocean aerosol products were produced. The newly developed MODIS over-ocean aerosol products will be used in operational aerosol assimilation and aerosol climatology studies, as well as other research based on MODIS products.

  12. Development of an Algorithm for MODIS and VIIRS Cloud Optical Property Data Record Continuity

    Science.gov (United States)

    Meyer, K.; Platnick, S. E.; Ackerman, S. A.; Heidinger, A. K.; Holz, R.; Wind, G.; Amarasinghe, N.; Marchant, B.

    2015-12-01

    The launch of Suomi NPP in the fall of 2011 began the next generation of U.S. operational polar orbiting environmental observations. Similar to MODIS, the VIIRS imager provides visible through IR observations at moderate spatial resolution with a 1330 LT equatorial crossing consistent with MODIS on the Aqua platform. However, unlike MODIS, VIIRS lacks key water vapor and CO2 absorbing channels used by the MODIS cloud algorithms for high cloud detection and cloud-top property retrievals. In addition, there is a significant change in the spectral location of the 2.1μm shortwave-infrared channel used by MODIS for cloud optical/microphysical retrievals. Given the instrument differences between MODIS EOS and VIIRS S-NPP/JPSS, we discuss our adopted method for merging the 15+ year MODIS observational record with VIIRS in order to generate cloud optical property data record continuity across the observing systems. The optical property retrieval code uses heritage algorithms that produce the existing MODIS cloud optical and microphysical properties product (MOD06). As explained in other presentations submitted to this session, the NOAA AWG/CLAVR-x cloud-top property algorithm and a common MODIS-VIIRS cloud mask feed into the optical property algorithm to account for the different channel sets of the two imagers. Data granule and aggregated examples for the current version of the algorithm will be shown.

  13. Validation of MODIS Total Precipitable Water Using Surface GPS Technology

    Science.gov (United States)

    Serra, Y. L.; Fears, A. J.; Moker, J.

    2014-12-01

    In this research we validate estimates of atmospheric total precipitable water (TPW) from the MODIS (Moderate Resolution Imaging Spectroradiometer) instruments onboard the Terra and Aqua satellites using surface Global Positioning System (GPS) derived TPW collected at ten stations across northwest Mexico during the 2013 North American monsoon (NAM) season. The MODIS Level 2 products provide TPW estimated from both the infrared (IR) and near-infrared (NIR) spectral bands and are available over the NAM region approximately twice per day. Our comparisons indicate that the correlations of Terra and Aqua IR TPW with the GPS observations are all significant at the 95% confidence level, while the NIR correlations show little or no significance. The analysis also finds that Terra and Aqua have significant seasonal biases with respect to the GPS for both the IR and NIR estimates at several locations, with the IR estimates showing better agreement than the NIR estimates. The dependence of the errors on elevation and time of overpass will be discussed to help identify contributing factors to the observed errors.

  14. Ten Years of Cloud Properties from MODIS: Global Statistics and Use in Climate Model Evaluation

    Science.gov (United States)

    Platnick, Steven E.

    2011-01-01

    The NASA Moderate Resolution Imaging Spectroradiometer (MODIS), launched onboard the Terra and Aqua spacecrafts, began Earth observations on February 24, 2000 and June 24,2002, respectively. Among the algorithms developed and applied to this sensor, a suite of cloud products includes cloud masking/detection, cloud-top properties (temperature, pressure), and optical properties (optical thickness, effective particle radius, water path, and thermodynamic phase). All cloud algorithms underwent numerous changes and enhancements between for the latest Collection 5 production version; this process continues with the current Collection 6 development. We will show example MODIS Collection 5 cloud climatologies derived from global spatial . and temporal aggregations provided in the archived gridded Level-3 MODIS atmosphere team product (product names MOD08 and MYD08 for MODIS Terra and Aqua, respectively). Data sets in this Level-3 product include scalar statistics as well as 1- and 2-D histograms of many cloud properties, allowing for higher order information and correlation studies. In addition to these statistics, we will show trends and statistical significance in annual and seasonal means for a variety of the MODIS cloud properties, as well as the time required for detection given assumed trends. To assist in climate model evaluation, we have developed a MODIS cloud simulator with an accompanying netCDF file containing subsetted monthly Level-3 statistical data sets that correspond to the simulator output. Correlations of cloud properties with ENSO offer the potential to evaluate model cloud sensitivity; initial results will be discussed.

  15. New methods for reducing cloud obscuration based on combination products of MODIS and AMSR2

    Science.gov (United States)

    Li, Muyi; Pan, Yaozhong; Zhu, Xiufang; Yin, Heyang

    2016-04-01

    As one of the main sources for water availability in semi-arid mountain regions, snow melt provides runoff and water supply for the downstream population and is of great importance for both human and environmental systems. For this reason, snow data such as snow cover (SCA) and snow depth (SD) is especially important. Snow cover has been mapped using many remote sensors in the visible, near-infrared, thermal, and microwave wavelengths. Since 1966, optical remote sensors such as AVHRR, Landsat and MODIS have obtained critically important data for observing the earth's snow cover. The Moderate Resolution Imaging Spectroradiometer (MODIS) employed by Terra and Aqua satellites provides spatially snow covered data with 500 m and daily temporal resolution. However the utility of the MODIS snow-cover products is limited by cloud cover which causes gaps in the daily snow-cover map products. In this paper, we developed a new method in order to reduce cloud obscuration. This method includes four parts: A) Combining various MODIS Terra and Aqua products; B) Temporal and spatial filtering; C) Zonal snowline approach and D) Combining the product deriving from the above three parts and the AMSR2 passive microwave snow depth product (with a spatial resolution of 10 km). In part D, the consistency of two different data (optical remote sensing data with spatial resolution of 500 m and passive microwave remote sensing data with a spatial resolution of 10 km) was evaluated. This study was carried out for Qinghai Province located in northwestern part of China during 1st, October, 2013 to 31st, March, 2015. In order to evaluate the performance of the proposed methodology, 14 MODIS snow cover product tiles (with cloud coverage less than 10%) were selected as possible "ground truth" data and cloud mask was generated for each tile randomly. The results show successful performances arising from the methods applied, which resulted in all cloud coverage being removed. The overall accuracy of

  16. The Effect of Deep Water Aqua Treadmill Training on the Plasma Biochemical Parameters of Show Jumpers

    Directory of Open Access Journals (Sweden)

    Anikó Vincze

    2013-09-01

    Full Text Available Aqua treadmill is mainly used for rehabilitation purposes, but research indicates that this equipment could be used for training as well. The few studies performed with aqua treadmill mainly followed lactate and heart rate changes. Therefore, the aim of this study was to test the effect of high water treadmill training on several blood parameters and on the correlations between them. Eight similarly trained Standardbred show jumper horse competing at the same level were selected with age between 6 to 11 years. The horses were subjected to a one week standardized exercise test which included normal training, training with show jumping and aqua treadmill training. The aqua treadmill training consisted of a 10 min walk (filling up, 4.5 km/h, 30 min trot (13 km/h and 4 min walk (emptying, 4.5 km/h. Blood samples were taken from the jugular vein before aqua training, at the completion of each work bout, after drying and after one and two hour rest. Blood plasma were separated and lactate, LDH, CK, AST, glucose, cholesterol, triglyceride, total-bilirubin and cortisol level were determined. In conclusion plasma lactate response itself does not reflect correctly the intensity of workload in high water level aqua training, therefore measurement of several blood parameters is advisable. Further studies needed to understand the relationship of metabolic processes altered due to the effect of partial water submersion.

  17. Earth System Science Research Using Datra and Products from Terra, Aqua, and ACRIM Satellites

    Science.gov (United States)

    Hutchison, Keith D.

    2007-01-01

    The report describes the research conducted at CSR to extend MODIS data and products to the applications required by users in the State of Texas. This research presented in this report was completed during the timeframe of August 2004 - December 31, 2007. However, since annual reports were filed in December 2005 and 2006, results obtained during calendar year 2007 are emphasized in the report. The stated goals of the project were to complete the fundamental research needed to create two types of new, Level 3 products for the air quality community in Texas from data collected by NASA s EOS Terra and Aqua missions.

  18. MONTHLY VARIABILITY OF TOTAL SUSPENDED MATTER (TSM) MAPPING USING MODIS 250M TO SUPPORT MARINE CULTURE AT MOROTAI ISLAND, NORTH MALUKU

    OpenAIRE

    KOMANG IWAN SUNIADA

    2015-01-01

    This study was conducted to provide an information of Total Suspended Matter concentration and its monthly variability using dialy data of Terra/ Aqua MOD IS level 1 b with spatial resolution 250m imagery at Morotai Island, Northern Maluku. TSM is one of the water quality key parameter to support finding suitable area which is an important step for marine culture activity. Dialy Aqua/Terra MODIS level lb, 250m dataset was downloaded freely from Goddard Space Flight Center, LAADS Web (http ://...

  19. MODIS/COMBINED MCD12C1 Land Cover Type Yearly L3 Global 0.05Deg CMG

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — MODIS/Terra+Aqua Land Cover Type Yearly L3 Global 0.05Deg CMG The Land Cover Type Yearly Climate Modeling Grid (CMG) is a lower spatial resolution (0.05?) product,...

  20. MODIS/COMBINED MCD12Q2 Land Cover Dynamics Yearly L3 Global 500 m SIN Grid

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — MODIS/Terra+Aqua Land Cover Type Yearly L3 Global 0.05Deg CMG The Land Cover Type Yearly Climate Modeling Grid (CMG) is a lower spatial resolution (0.05?) product,...

  1. MODIS/COMBINED MCD12Q1 Land Cover Type Yearly L3 Global 500 m SIN Grid

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — MODIS/Terra+Aqua Land Cover Type Yearly L3 Global 0.05Deg CMG The Land Cover Type Yearly Climate Modeling Grid (CMG) is a lower spatial resolution (0.05?) product,...

  2. Recent Progress on Deep Blue Aerosol Algorithm as Applied TO MODIS, SEA WIFS, and VIIRS, and Their Intercomparisons with Ground Based and Other Satellite Measurements

    Science.gov (United States)

    Hsu, N. Christina; Bettenhausen, Corey; Sawyer, Andrew; Tsay, Si-Chee

    2012-01-01

    The impact of natural and anthropogenic sources of aerosols has gained increasing attention from scientific communities in recent years. Indeed, tropospheric aerosols not only perturb radiative energy balance by interacting with solar and terrestrial radiation, but also by changing cloud properties and lifetime. Furthermore, these anthropogenic and natural air particles, once generated over the source regions, can be transported out of the boundary layer into the free troposphere and can travel thousands of kilometers across oceans and continents resulting in important biogeochemical impacts on the ecosystem. With the launch of SeaWiFS in 1997, Terra/MODIS in 1999, and Aqua/MODIS in 2002, high quality comprehensive aerosol climatology is becoming feasible for the first time. As a result of these unprecedented data records, studies of the radiative and biogeochemical effects due to tropospheric aerosols are now possible. In this talk, we will demonstrate how this newly available SeaWiFS/MODIS aerosol climatology can provide an important piece of puzzles in reducing the uncertainty of estimated climatic forcing due to aerosols. We will start with the global distribution of aerosol loading and their variabilities over both land and ocean on short- and long-term temporal scales observed over the last decade. The recent progress made in Deep Blue aerosol algorithm on improving accuracy of these Sea WiFS / MODIS aerosol products in particular over land will be discussed. The impacts on quantifying physical and optical processes of aerosols over source regions of adding the Deep Blue products of aerosol properties over bright-reflecting surfaces into Sea WiFS / MODIS as well as VIIRS data suite will also be addressed. We will also show the intercomparison results of SeaWiFS/MODIS retrieved aerosol optical thickness with data from ground based AERONET sunphotometers over land and ocean as well as with other satellite measurements. The trends observed in global aerosol

  3. MODIS/Terra Clear Sky Radiance 8-Day Composite Daily L3 Global 25km Equal Area V006

    Data.gov (United States)

    National Aeronautics and Space Administration — MODIS 8-day averaged clear-sky radiance (thermal bands) and reflectance (visible bands) statistics in selected MODIS bands are stored on a global grid map....

  4. MODIS/Terra Clear Sky Radiance Statistics Daily L3 Global 25km Equal Area V006

    Data.gov (United States)

    National Aeronautics and Space Administration — MODIS daily averaged clear-sky radiance (thermal bands) and reflectance (visible bands) statistics in selected MODIS bands are stored on a global grid map....

  5. Determining the accuracies of sea-surface temperatures derived from measurements of MODIS and VIIRS

    Science.gov (United States)

    Minnett, P. J.; Kilpatrick, K. A.; Podesta, G. P.; Izaguirre, M.; Williams, E.; Walsh, S.

    2015-12-01

    The appropriate application of sea-surface temperatures (SSTs) derived from MODIS and VIIRS requires knowledge of the errors and uncertainties of the SST fields. The accuracies of the SSTs are determined by comparison with independent measurements, usually derived from drifting and moored buoys, and ship-board radiometers. By using similar cloud detection and clear-sky atmospheric correction algorithms to derived SST from both MODIS's on Terra and Aqua, and the VIIRS on S-NPP a consistent time series of SSTs can be derived from the first useful Terra MODIS data in 2000 to the present, and by using the same approach to assess their accuracies, a consistent set of errors and uncertainties can also be derived. The presentation will provide a summary of recently modified algorithms used to derive SSTs from the MODIS's and VIIRS, and discuss the accuracies of the derived fields, including recent improvements to the VIIRS atmospheric correction algorithm to reduce the effects of instrumental artifacts.

  6. Contribution of MODIS Derived Snow Cover Satellite Data into Artificial Neural Network for Streamflow Estimation

    Science.gov (United States)

    Uysal, Gokcen; Arda Sorman, Ali; Sensoy, Aynur

    2014-05-01

    Contribution of snowmelt and correspondingly snow observations are highly important in mountainous basins for modelers who deal with conceptual, physical or soft computing models in terms of effective water resources management. Long term archived continuous data are needed for appropriate training and testing of data driven approaches like artificial neural networks (ANN). Data is scarce at the upper elevations due to the difficulty of installing sufficient automated SNOTEL stations; thus in literatures many attempts are made on the rainfall dominated basins for streamflow estimation studies. On the other hand, optical satellites can easily detect snow because of its high reflectance property. MODIS (Moderate Resolution Imaging Spectroradiometer) satellite that has two platforms (Terra and Aqua) provides daily and 8-daily snow images for different time periods since 2000, therefore snow cover data (SCA) may be useful as an input layer for ANN applications. In this study, a multi-layer perceptron (MLP) model is trained and tested with precipitation, temperature, radiation, previous day discharges as well as MODIS daily SCA data. The weights and biases are optimized with fastest and robust Levenberg-Marquardt backpropagation algorithm. MODIS snow cover images are removed from cloud coverage using certain filtering techniques. The Upper Euphrates River Basin in eastern part of Turkey (10 250 km2) is selected as the application area since it is fed by snowmelt approximately 2/3 of total annual volume during spring and early summer. Several input models and ANN structures are investigated to see the effect of the contributions using 10 years of data (2001-2010) for training and validation. The accuracy of the streamflow estimations is checked with statistical criteria (coefficient of determination, Nash-Sutcliffe model efficiency, root mean square error, mean absolute error) and the results seem to improve when SCA data is introduced. Furthermore, a forecast study is

  7. The Aqua-Planet Experiment (APE): CONTROL SST Simulation

    Science.gov (United States)

    Blackburn, Michael; Williamson, David L.; Nakajima, Kensuke; Ohfuchi, Wataru; Takahashi, Yoshiyuki O.; Hayashi, Yoshi-Yuki; Nakamura, Hisashi; Ishiwatari, Masaki; Mcgregor, John L.; Borth, Hartmut; Wirth, Volkmar; Frank, Helmut; Bechtold, Peter; Wedi, Nils P.; Tomita, Hirofumi; Satoh, Masaki; Zhao, Ming; Held, Isaac M.; Suarez, Max J.; Lee, Myong-In; Watanabe, Masahiro; Kimoto, Masahide; Liu, Yimin; Wang, Zaizhi; Molod, Andrea M.; Rajendran, Kavirajan; Kotoh, Akio; Stratton, Rachel

    2013-01-01

    Climate simulations by 16 atmospheric general circulation models (AGCMs) are compared on an aqua-planet, a water-covered Earth with prescribed sea surface temperature varying only in latitude. The idealised configuration is designed to expose differences in the circulation simulated by different models. Basic features of the aqua-planet climate are characterised by comparison with Earth. The models display a wide range of behaviour. The balanced component of the tropospheric mean flow, and mid-latitude eddy covariances subject to budget constraints, vary relatively little among the models. In contrast, differences in damping in the dynamical core strongly influence transient eddy amplitudes. Historical uncertainty in modelled lower stratospheric temperatures persists in APE.Aspects of the circulation generated more directly by interactions between the resolved fluid dynamics and parameterized moist processes vary greatly. The tropical Hadley circulation forms either a single or double inter-tropical convergence zone (ITCZ) at the equator, with large variations in mean precipitation. The equatorial wave spectrum shows a wide range of precipitation intensity and propagation characteristics. Kelvin mode-like eastward propagation with remarkably constant phase speed dominates in most models. Westward propagation, less dispersive than the equatorial Rossby modes, dominates in a few models or occurs within an eastward propagating envelope in others. The mean structure of the ITCZ is related to precipitation variability, consistent with previous studies.The aqua-planet global energy balance is unknown but the models produce a surprisingly large range of top of atmosphere global net flux, dominated by differences in shortwave reflection by clouds. A number of newly developed models, not optimised for Earth climate, contribute to this. Possible reasons for differences in the optimised models are discussed.The aqua-planet configuration is intended as one component of an

  8. Improved VIIRS and MODIS SST Imagery

    Directory of Open Access Journals (Sweden)

    Irina Gladkova

    2016-01-01

    Full Text Available Moderate Resolution Imaging Spectroradiometers (MODIS and Visible Infrared Imaging Radiometer Suite (VIIRS radiometers, flown onboard Terra/Aqua and Suomi National Polar-orbiting Partnership (S-NPP/Joint Polar Satellite System (JPSS satellites, are capable of providing superior sea surface temperature (SST imagery. However, the swath data of these multi-detector sensors are subject to several artifacts including bow-tie distortions and striping, and require special pre-processing steps. VIIRS additionally does two irreversible data reduction steps onboard: pixel aggregation (to reduce resolution changes across the swath and pixel deletion, which complicate both bow-tie correction and destriping. While destriping was addressed elsewhere, this paper describes an algorithm, adopted in the National Oceanic and Atmospheric Administration (NOAA Advanced Clear-Sky Processor for Oceans (ACSPO SST system, to minimize the bow-tie artifacts in the SST imagery and facilitate application of the pattern recognition algorithms for improved separation of ocean from cloud and mapping fine SST structure, especially in the dynamic, coastal and high-latitude regions of the ocean. The algorithm is based on a computationally fast re-sampling procedure that ensures a continuity of corresponding latitude and longitude arrays. Potentially, Level 1.5 products may be generated to benefit a wide range of MODIS and VIIRS users in land, ocean, cryosphere, and atmosphere remote sensing.

  9. Radiative effects of global MODIS cloud regimes

    Science.gov (United States)

    Oreopoulos, Lazaros; Cho, Nayeong; Lee, Dongmin; Kato, Seiji

    2016-03-01

    We update previously published Moderate Resolution Imaging Spectroradiometer (MODIS) global cloud regimes (CRs) using the latest MODIS cloud retrievals in the Collection 6 data set. We implement a slightly different derivation method, investigate the composition of the regimes, and then proceed to examine several aspects of CR radiative appearance with the aid of various radiative flux data sets. Our results clearly show that the CRs are radiatively distinct in terms of shortwave, longwave, and their combined (total) cloud radiative effect. We show that we can clearly distinguish regimes based on whether they radiatively cool or warm the atmosphere, and thanks to radiative heating profiles, to discern the vertical distribution of cooling and warming. Terra and Aqua comparisons provide information about the degree to which morning and afternoon occurrences of regimes affect the symmetry of CR radiative contribution. We examine how the radiative discrepancies among multiple irradiance data sets suffering from imperfect spatiotemporal matching depend on CR and whether they are therefore related to the complexity of cloud structure, its interpretation by different observational systems, and its subsequent representation in radiative transfer calculations.

  10. MODIS Cloud Microphysics Product (MOD_PR06OD) Data Collection 6 Updates

    Science.gov (United States)

    Wind, Gala; Platnick, Steven; King, Michael D.

    2014-01-01

    The MODIS Cloud Optical and Microphysical Product (MOD_PR060D) for Data Collection 6 has entered full scale production. Aqua reprocessing is almost completed and Terra reprocessing will begin shortly. Unlike previous collections, the CHIMAERA code base allows for simultaneous processing for multiple sensors and the operational CHIMAERA 6.0.76 stream is also available for VIIRS and SEVIRI sensors and for our E-MAS airborne platform.

  11. Evaluating MODIS cloud retrievals with in situ observations from VOCALS-REx

    OpenAIRE

    King, N. J.; K. N. Bower; Crosier, J.; I. Crawford

    2013-01-01

    Microphysical measurements collected during eleven profiles, by the UK BAe-146 aircraft, through marine stratocumulus as part of the Variability of the American Monsoon Systems (VAMOS) Ocean-Cloud-Atmosphere-Land Study Regional Experiment (VOCALS-REx) are compared to collocated overpasses of the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard the Aqua and Terra satellite platforms. The full depth of the cloud is sampled in each case using a Cloud Droplet Probe (CDP) and a Two-Dim...

  12. Estimating Daily Land Surface Temperatures in Mountainous Environments by Reconstructed MODIS LST Data

    OpenAIRE

    Markus Neteler

    2010-01-01

    Continuous monitoring of extreme environments, such as the European Alps, is hampered by the sparse and/or irregular distribution of meteorological stations, the difficulties in performing ground surveys and the complexity of interpolating existing station data. Remotely sensed Land Surface Temperature (LST) is therefore of major interest for a variety of environmental and ecological applications. But while MODIS LST data from the Terra and Aqua satellites are aimed at closing the gap between...

  13. Comparison of AOD between CALIPSO and MODIS: significant differences over major dust and biomass burning regions

    OpenAIRE

    X. Ma; Bartlett, K; K. Harmon; F. Yu

    2013-01-01

    Cloud–Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) provide global vertical profiles of aerosol optical properties for the first time. In this study, we employed about 6 yr (2006–2011) of CALIPSO level 3 monthly mean gridded aerosol optical depth (AOD) products (daytime and nighttime) for cloud-free conditions, to compare with the Moderate Resolution Imaging Spectroradiometer (MODIS) Terra/Aqua level 3 monthly mean AOD dataset for the same time peri...

  14. Detailed Evaluation of MODIS Fire Radiative Power Measurements

    Science.gov (United States)

    Ichoku, Charles

    2010-01-01

    Satellite remote sensing is providing us tremendous opportunities to measure the fire radiative energy (FRE) release rate or power (FRP) from open biomass burning, which affects many vegetated regions of the world on a seasonal basis. Knowledge of the biomass burning characteristics and emission source strengths of different (particulate and gaseous) smoke constituents is one of the principal ingredients upon which the assessment, modeling, and forecasting of their distribution and impacts depend. This knowledge can be gained through accurate measurement of FRP, which has been shown to have a direct relationship with the rates of biomass consumption and emissions of major smoke constituents. Over the last decade or so, FRP has been routinely measured from space by both the MODIS sensors aboard the polar orbiting Terra and Aqua satellites, and the SEVIRI sensor aboard the Meteosat Second Generation (MSG) geostationary satellite. During the last few years, FRP has been gaining recognition as an important parameter for facilitating the development of various scientific studies relating to the quantitative characterization of biomass burning and their emissions. Therefore, we are conducting a detailed analysis of the FRP products from MODIS to characterize the uncertainties associated with them, such as those due to the MODIS bow-tie effects and other factors, in order to establish their error budget for use in scientific research and applications. In this presentation, we will show preliminary results of the MODIS FRP data analysis, including comparisons with airborne measurements.

  15. Investigating the impact of haze on MODIS cloud detection

    Science.gov (United States)

    Mao, Feiyue; Duan, Miaomiao; Min, Qilong; Gong, Wei; Pan, Zengxin; Liu, Guangyi

    2015-12-01

    The cloud detection algorithm for passive sensors is usually based on a fuzzy logic system with thresholds determined from previous observations. In recent years, haze and high aerosol concentrations with high aerosol optical depth (AOD) occur frequently in China and may critically impact the accuracy of the Moderate Resolution Imaging Spectroradiometer (MODIS) cloud detection. Thus, we comprehensively explore this impact by comparing the results from MODIS/Aqua (passive sensor), Cloud-Aerosol Lidar with Orthogonal Polarization/CALIPSO (lidar sensor), and Cloud Profiling Radar/CloudSat (microwave sensor) of the A-Train suite of instruments using an averaged AOD as an index for an aerosol concentration value. Case studies concerning the comparison of the three sensors indicate that MODIS cloud detection is reduced during haze events. In addition, statistical studies show that an increase in AOD creates an increase in the percentage of uncertain flags and a decrease in hit rate, a consistency index between consecutive sets of cloud retrievals. On average, AOD values lower than 0.1 give hit rate values up to 80.0% and uncertainty values lower than 16.8%, while AOD values greater than 1.0 reduce the hit rate below to 66.6% and increase the percentage of uncertain flags up to 46.6%. Therefore, we can conclude that the ability of MODIS cloud detection is weakened by large concentrations of aerosols. This suggests that use of the MODIS cloud mask, and derived higher-level products, in situations with haze requires caution. Further improvement of this retrieval algorithm is desired as haze studies based on MODIS products are of great interest in a number of related fields.

  16. Accuracy assessment of Terra-MODIS aerosol optical depth retrievals

    International Nuclear Information System (INIS)

    Moderate Resolution Imaging Spectroradiometer (MODIS) aerosol products have been widely used to address environment and climate change subjects with daily global coverage. Aerosol optical depth (AOD) is retrieved by different algorithms based on the pixel surface, determining between land and ocean. MODIS-Terra and Global Aerosol Robotic Network (AERONET) products can be obtained from the Multi-sensor Aerosol Products Sampling System (MAPSS) for coastal regions during 2000-2010. Using data collected from 83 coastal stations worldwide from AERONET from 2000-2010, accuracy assessments are made for coastal aerosol optical depth (AOD) retrieved from MODIS aboard the Terra satellite. AOD retrieved from MODIS at 0.55μm wavelength has been compared With the AERONET derived AOD, because it is reliable with the major wavelength used by many chemistry transport and climate models as well as previous MODIS validation studies. After removing retrievals with quality flags below1 for Ocean algorithm and below 3 for Land algorithm, The accuracy of AOD retrieved from MODIS Dark Target Ocean algorithms (correlation coefficient R2 is 0.844 and a regression equation of τM = 0.91·τA + 0.02 (where subscripts M and A represent MODIS and AERONET respectively), is the greater than the MODIS Dark Target Land algorithms (correlation coefficient R2 is 0.764 and τM = 0.95·τA + 0.03) and the Deep Blue algorithm (correlation coefficient R2 is 0.652 and τM = 0.81·τA + 0.04). The reasons of the retrieval error in AOD are found to be the various underlying surface reflectance. Therefore, the aerosol models and underlying surface reflectance are the dominant factors which influence the accuracy of MODIS retrieval performance. Generally the MODIS Land algorithm implements better than the Ocean algorithm for coastal sites

  17. Study of Modis satellite derived aerosol angstrom exponent and in-situ measured values using Sun photometer in part of the west coast of Indian Peninsula

    Digital Repository Service at National Institute of Oceanography (India)

    SunilKumar R.K.; Suresh, T.; Govindaraju; SureshKumar, B.V.

    comparatively high AAE with that of Malvan and Murdeshwar (Fig.6a,b) Based on industrial and mining activity. 6. Conclusions The study of comparing the in-situ estimated AAE with that the MODIS Aqua derived AAE has provided an opportunity to learn the method...

  18. On-Orbit Spatial Characterization of MODIS with ASTER Aboard the Terra Spacecraft

    Science.gov (United States)

    Xie, Yong; Xiong, Xiaoxiong

    2011-01-01

    This letter presents a novel approach for on-orbit characterization of MODerate resolution Imaging Spectroradiometer (MODIS) band-to-band registration (BBR) using Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) aboard the Terra spacecraft. The spatial resolution of ASTER spectral bands is much higher than that of MODIS, making it feasible to characterize MODIS on-orbit BBR using their simultaneous observations. The ground target selected for on-orbit MODIS BBR characterization in this letter is a water body, which is a uniform scene with high signal contrast relative to its neighbor areas. A key step of this approach is to accurately localize the measurements of each MODIS band in an ASTER measurement plane coordinate (AMPC). The ASTER measurements are first interpolated and aggregated to simulate the measurements of each MODIS band. The best measurement match between ASTER and each MODIS band is obtained when the measurement difference reaches its weighted minimum. The position of each MODIS band in the AMPC is then used to calculate the BBR. The results are compared with those derived from MODIS onboard Spectro-Radiometric Calibration Assembly. They are in good agreement, generally less than 0.1 MODIS pixel. This approach is useful for other sensors without onboard spatial characterization capability. Index Terms Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), band-to-band registration (BBR), MODerate resolution Imaging Spectroradiometer (MODIS), spatial characterization.

  19. 基于实测光谱分析和MODIS数据鄱阳湖叶绿素a浓度估算%ESTIMATING CHLOROPHYLL-A CONCENTRATION IN POYANG LAKE USING MODIS BASED ON MEASURED REFLECTANCE SPECTRA

    Institute of Scientific and Technical Information of China (English)

    张永杰; 王卷乐; 冉盈盈; 杨飞; 曹晓明; 郭海会

    2013-01-01

    基于遥感的大面积水体监测技术为水环境监测提供了一种有效手段.以鄱阳湖为研究区,以反映水体营养状态的重要指标叶绿素a为研究对象,在测定研究区水体光谱及叶绿素a浓度和收集了相应时间的MODIS数据的基础上,采用浮游藻类指数法(Floating Algae Index,FAI)提取鄱阳湖水体范围,对鄱阳湖水体实测光谱数据进行剔除异常、归一化及光谱微分处理,构建波段差值、比值、归一化差值等光谱指数,利用最小二乘原理迭代分析水体叶绿素光谱响应特征,得出敏感波段范围:673~680 nm与650~665 nm、680~710 nm与650~670 nm、662~671 nm与700~720 nm光谱区间组合.选择最佳通道组合,建立基于MODIS影像的鄱阳湖叶绿素a浓度反演模型,相关系数为0.67.应用该模型得到2011年秋季鄱阳湖的叶绿素浓度估算值,反演结果显示湖区水体叶绿素浓度总体不高,且在空间分布上湖区水体周边与陆地交界处比湖中心区浓度偏高.分析认为:通过对实测光谱的定量分析,获得对鄱阳湖地区水体叶绿素浓度的光谱特征认识,揭示出其反射光谱的长波漂移现象,为鄱阳湖这一富营养化程度底,且水体分布不均匀区域建立一种叶绿素浓度反演方法,可为该区域长期的水环境管理提供方法借鉴.%It is an efficient method of water environment survey to using remote sensing data for large area water quality monitoring.The Poyang Lake was selected as the research area in this research.The chlorophyll-a content which gives an important index to eutrophic state of water was chosen as the study object.The water reflectance spectra were acquired with an ASD FieldSpec HH (350-1050nm) and the MODIS data collected during the same period.Based on MODIS data,the range of the Poyang Lake was extracted by a approach named Floating Algae Index (FAI).After the measured spectra were preprocessed with deleted abnormal data

  20. An Emerging Global Aerosol Climatology from the MODIS Satellite Sensors

    Science.gov (United States)

    Remer, Lorraine A.; Kleidman, Richard G.; Levy, Robert C.; Kaufman, Yoram J.; Tanre, Didier; Mattoo, Shana; Martins, J. Vandelei; Ichoku, Charles; Koren, Ilan; Hongbin, Yu; Holben, Brent N.

    2008-01-01

    The recently released Collection 5 MODIS aerosol products provide a consistent record of the Earth's aerosol system. Comparison with ground-based AERONET observations of aerosol optical depth (AOD) we find that Collection 5 MODIS aerosol products estimate AOD to within expected accuracy more than 60% of the time over ocean and more than 72% of the time over land. This is similar to previous results for ocean, and better than the previous results for land. However, the new Collection introduces a 0.01 5 offset between the Terra and Aqua global mean AOD over ocean, where none existed previously. Aqua conforms to previous values and expectations while Terra is high. The cause of the offset is unknown, but changes to calibration are a possible explanation. We focus the climatological analysis on the better understood Aqua retrievals. We find that global mean AOD at 550 nm over oceans is 0.13 and over land 0.19. AOD in situations with 80% cloud fraction are twice the global mean values, although such situations occur only 2% of the time over ocean and less than 1% of the time over land. There is no drastic change in aerosol particle size associated with these very cloudy situations. Regionally, aerosol amounts vary from polluted areas such as East Asia and India, to the cleanest regions such as Australia and the northern continents. In almost all oceans fine mode aerosol dominates over dust, except in the tropical Atlantic downwind of the Sahara and in some months the Arabian Sea.

  1. Cloud Properties of CERES-MODIS Edition 4 and CERES-VIIRS Edition 1

    Science.gov (United States)

    Sun-Mack, Sunny; Minnis, Patrick; Chang, Fu-Lung; Hong, Gang; Arduini, Robert; Chen, Yan; Trepte, Qing; Yost, Chris; Smith, Rita; Brown, Ricky; Chu, Churngwei; Heckert, Elizabeth; Gibson, Sharon; Heck, Patrick W.

    2015-01-01

    The Clouds and Earth's Radiant Energy System (CERES) analyzes MODerate-resolution Imaging Spectroradiometer (MODIS) data and Visible Infrared Imaging Radiometer Suite (VIIRS) to derive cloud properties that are combine with aerosol and CERES broadband flux data to create a multi-parameter data set for climate study. CERES has produced over 15 years of data from Terra and over 13 years of data from Aqua using the CERES-MODIS Edition-2 cloud retrieval algorithm. A recently revised algorithm, CERESMODIS Edition 4, has been developed and is now generating enhanced cloud data for climate research (over 10 years for Terra and 8 years for Aqua). New multispectral retrievals of properties are included along with a multilayer cloud retrieval system. Cloud microphysical properties are reported at 3 wavelengths, 0.65, 1.24, and 2.1 microns to enable better estimates of the vertical profiles of cloud water contents. Cloud properties over snow are retrieved using the 1.24-micron channel. A new CERES-VIIRS cloud retrieval package was developed for the VIIRS spectral complement and is currently producing the CERES-VIIRS Edition 1 cloud dataset. The results from CERES-MODIS Edition 4 and CERES-VIIRS Edition 1 are presented and compared with each other and other datasets, including CALIPSO, CloudSat and the CERES-MODIS Edition-2 results.

  2. Evaluation of MODIS vegetation indices for detecting deforestation in Amazonia

    OpenAIRE

    Yosio Edemir Shimabukuro; Antonio Roberto Formaggio; Antonio Henrique Correia; Valdete Duarte

    2007-01-01

    Vegetation indices (NDVI and EVI) obtained from MODIS products (250 m and 500m, surface reflectance) were evaluated in relation to the possibility of detecting and monitoring deforestation areas in Amazonia. A new vegetation index, the DNRG (Normalized Difference between Red and Green spectral bands), was proposed with the same objective. The radiometric quality of the multi-date MODIS products was evaluated to verify the possibility of using vegetation index to generate deforestation maps. T...

  3. Using MODIS data

    OpenAIRE

    Zidarič, Tine

    2007-01-01

    Remote sensing is used every day for gathering information about the environment, land, ocean or atmosphere. Many satellites circle the Earth equipped with sensors, which »observe« the Earth and provide us data about the health of our environment. In this work we focused on the MODIS sensor, which is one of the newest and most advanced satellite remote sensing sensors today. The first part of this work deals with reasons for design and launch of MODIS and its main attributes. Main technical a...

  4. Assessment of the MODIS-Terra Collection 006 aerosol optical depth data over the greater Mediterranean basin and inter-comparison against MODIS C005 and AERONET

    Science.gov (United States)

    Betsikas, Marios; Hatzianastassiou, Nikos; Papadimas, Christos D.; Gkikas, Antonis; Matsoukas, Christos; Sayer, Andrew; Hsu, Christina; Vardavas, Ilias

    2016-04-01

    Aerosols are one of the key factors determining the Earth's solar radiation budget. The aerosol radiative effects are strongly dependent on aerosol optical depth (AOD) which is a good measure of atmospheric aerosol loading. Therefore, understanding better the spatial and temporal patterns of AOD at both global and regional scales is important for more accurate estimations of aerosol radiative effects. Nowadays, improved globally distributed AOD products are available largely based on satellite observations. Currently, one of the most acknowledged accurate AOD dataset is the one derived from measurements of the MODerate resolution Imaging Spectroradiometer (MODIS) instrument onboard the twin Earth Observing System (EOS) Terra and Aqua satellite platforms. The MODIS aerosol retrieval algorithm, which is used to produce AOD data, is continuously improved and updated, leading to releases of successive series, named as Collections. Recently, MODIS Collection 6 (C006) dataset has been made available. Despite their advantages, satellite AOD products have to be assessed through comparisons against ground based AOD products, such as those from AERosol Robotic Network (AERONET). The aim of the present study is to assess the newest MODIS C006 AOD product over the greater Mediterranean basin. The assessment is performed through comparisons of the MODIS-Terra C006 Level-3 AOD data against corresponding data from the previous C005 MODIS dataset, as well as versus AOD data from AERONET stations within the study region. The study period extends from 2001 to 2012 and our comparisons are performed on a monthly basis. Emphasis is given on differences between the MODIS C006 AOD data and corresponding previous C005 data, as to their spatial and temporal, seasonal and inter-annual, patterns. The results show a better agreement of MODIS C006 than C005 AOD data with AERONET, while the C006 data offer a complete spatial coverage of the study region, specifically over the northern African

  5. Long Term Cloud Property Datasets From MODIS and AVHRR Using the CERES Cloud Algorithm

    Science.gov (United States)

    Minnis, Patrick; Bedka, Kristopher M.; Doelling, David R.; Sun-Mack, Sunny; Yost, Christopher R.; Trepte, Qing Z.; Bedka, Sarah T.; Palikonda, Rabindra; Scarino, Benjamin R.; Chen, Yan; Hong, Gang; Bhatt, Rajendra

    2015-01-01

    Cloud properties play a critical role in climate change. Monitoring cloud properties over long time periods is needed to detect changes and to validate and constrain models. The Clouds and the Earth's Radiant Energy System (CERES) project has developed several cloud datasets from Aqua and Terra MODIS data to better interpret broadband radiation measurements and improve understanding of the role of clouds in the radiation budget. The algorithms applied to MODIS data have been adapted to utilize various combinations of channels on the Advanced Very High Resolution Radiometer (AVHRR) on the long-term time series of NOAA and MetOp satellites to provide a new cloud climate data record. These datasets can be useful for a variety of studies. This paper presents results of the MODIS and AVHRR analyses covering the period from 1980-2014. Validation and comparisons with other datasets are also given.

  6. Use of Linear Spectral Mixture Model to Estimate Rice Planted Area Based on MODIS Data

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    MODIS (Moderate Resolution Imaging Spectroradiometer) is a key instrument aboard the Terra (EOS AM) and Aqua (EOS PM) satellites.Linear spectral mixture models are applied to MOIDS data for the sub-pixel classification of land covers.Shaoxing county of Zhcjiang Province in China was chosen to be the study site and early rice was selected as the study crop.The derived proportions of land covers from MODIS pixel using linear spectral mixture models were compared with unsupervised classification derived from TM data acquired on the same day,which implies that MODIS data could be used as satellite data source for rice cultivation area estimation,possibly rice growth monitoring and yield forecasting on the regional scale.

  7. Validation and empirical correction of MODIS AOT and AE over ocean

    Directory of Open Access Journals (Sweden)

    N. A. J. Schutgens

    2013-09-01

    Full Text Available We present a validation study of Collection 5 MODIS level 2 Aqua and Terra AOT (aerosol optical thickness and AE (Ångström exponent over ocean by comparison to coastal and island AERONET (AErosol RObotic NETwork sites for the years 2003–2009. We show that MODIS (MODerate-resolution Imaging Spectroradiometer AOT exhibits significant biases due to wind speed and cloudiness of the observed scene, while MODIS AE, although overall unbiased, exhibits less spatial contrast on global scales than the AERONET observations. The same behaviour can be seen when MODIS AOT is compared against Maritime Aerosol Network (MAN data, suggesting that the spatial coverage of our datasets does not preclude global conclusions. Thus, we develop empirical correction formulae for MODIS AOT and AE that significantly improve agreement of MODIS and AERONET observations. We show these correction formulae to be robust. Finally, we study random errors in the corrected MODIS AOT and AE and show that they mainly depend on AOT itself, although small contributions are present due to wind speed and cloud fraction in AOT random errors and due to AE and cloud fraction in AE random errors. Our analysis yields significantly higher random AOT errors than the official MODIS error estimate (0.03 + 0.05 τ, while random AE errors are smaller than might be expected. This new dataset of bias-corrected MODIS AOT and AE over ocean is intended for aerosol model validation and assimilation studies, but also has consequences as a stand-alone observational product. For instance, the corrected dataset suggests that much less fine mode aerosol is transported across the Pacific and Atlantic oceans.

  8. Recent Shift of Deforestation to High Elevation Areas from 2001 to 2013 in Borneo Detected by MODIS Data

    Science.gov (United States)

    Nagai, S.; Suzuki, R.

    2015-12-01

    The biomass of tropical forests sequestrates tons of carbon and plays an important role in the global carbon cycle regulating the climate. Also its high biodiversity ecosystems bring us many valuable resources and cultural and educational ecosystem services. However, large areas of the tropical forest are deforested and converted to oil palm or acacia plantation for the economic benefit of the local society mainly in Southeast Asia. Monitoring of the tropical forest from satellites provides us the information about the deforestation for decadal time period over extensive areas and enables us to discuss it from a scientific point of view. The purpose of this study is to reveal the interannual change and recent trend of deforestation in relation to the land elevation for decadal time period over Borneo by using data from Moderate Resolution Imaging Spectroradiometer (MODIS). We acquired the atmospherically corrected and cloud free Terra-MODIS and Aqua-MODIS daily data products (MOD09GA and MYD09GA; collection 5) from 2001 to 2013 for Borneo. We extracted the pixel values in the 500m surface reflectance bands 1 (red) and 4 (green) products and calculated the green-red vegetation index (GRVI), (band 4 - band 1) / (band 4 + band 1), at a daily time step. GRVI shows a positive value for the land prevailed by green vegetation, while it shows a negative value for the land prevailed by no-green components such as bare land. As for the elevation data, ASTER Global Digital Elevation Model (GDEM) which has 33.3m spatial resolution was employed. The original resolution was resampled to the grid system of MODIS data (i.e. 500m resolution). Pixels which had a negative GRVI ratio more than 80 % (termed as "no green pixel") in each year were regarded as the land characterized by no vegetation, and mapped the distribution for each year. Throughout the 13 years, no green pixels mainly found over the coastal low land below 20m of the elevation and the area was almost constant (around

  9. A reanalysis of MODIS fine mode fraction over ocean using OMI and daily GOCART simulations

    Directory of Open Access Journals (Sweden)

    T. A. Jones

    2011-06-01

    Full Text Available Using daily Goddard Chemistry Aerosol Radiation and Transport (GOCART model simulations and columnar retrievals of 0.55 μm aerosol optical thickness (AOT and fine mode fraction (FMF from the Moderate Resolution Imaging Spectroradiometer (MODIS, we estimate the satellite-derived aerosol properties over the global oceans between June 2006 and May 2007 due to black carbon (BC, organic carbon (OC, dust (DU, sea-salt (SS, and sulfate (SU components. Using Aqua-MODIS aerosol properties embedded in the CERES-SSF product, we find that the mean MODIS FMF values for each aerosol type are SS: 0.31 ± 0.09, DU: 0.49 ± 0.13, SU: 0.77 ± 0.16, and (BC + OC: 0.80 ± 0.16. We further combine information from the ultraviolet spectrum using the Ozone Monitoring Instrument (OMI onboard the Aura satellite to improve the classification process, since dust and carbonate aerosols have positive Aerosol Index (AI values >0.5 while other aerosol types have near zero values. By combining MODIS and OMI datasets, we were able to identify and remove data in the SU, OC, and BC regions that were not associated with those aerosol types.

    The same methods used to estimate aerosol size characteristics from MODIS data within the CERES-SSF product were applied to Level 2 (L2 MODIS aerosol data from both Terra and Aqua satellites for the same time period. As expected, FMF estimates from L2 Aqua data agreed well with the CERES-SSF dataset from Aqua. However, the FMF estimate for DU from Terra data was significantly lower (0.37 vs. 0.49 indicating that sensor calibration, sampling differences, and/or diurnal changes in DU aerosol size characteristics were occurring. Differences for other aerosol types were generally smaller. Sensitivity studies show that a difference of 0.1 in the estimate of the anthropogenic component of FMF produces a corresponding change of 0.2 in the anthropogenic component of AOT (assuming a unit value of AOT. This uncertainty would then be passed

  10. Evaluation of VIIRS, GOCI, and MODIS Collection 6 AOD retrievals against ground sunphotometer observations over East Asia

    Science.gov (United States)

    Xiao, Q.; Zhang, H.; Choi, M.; Li, S.; Kondragunta, S.; Kim, J.; Holben, B.; Levy, R. C.; Liu, Y.

    2016-02-01

    Persistent high aerosol loadings together with extremely high population densities have raised serious air quality and public health concerns in many urban centers in East Asia. However, ground-based air quality monitoring is relatively limited in this area. Recently, satellite-retrieved Aerosol Optical Depth (AOD) at high resolution has become a powerful tool to characterize aerosol patterns in space and time. Using ground AOD observations from the Aerosol Robotic Network (AERONET) and the Distributed Regional Aerosol Gridded Observation Networks (DRAGON)-Asia Campaign, as well as from handheld sunphotometers, we evaluated emerging aerosol products from the Visible Infrared Imaging Radiometer Suite (VIIRS) aboard the Suomi National Polar-orbiting Partnership (S-NPP), the Geostationary Ocean Color Imager (GOCI) aboard the Communication, Ocean, and Meteorology Satellite (COMS), and Terra and Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) (Collection 6) in East Asia in 2012 and 2013. In the case study in Beijing, when compared with AOD observations from handheld sunphotometers, 51 % of VIIRS Environmental Data Record (EDR) AOD, 37 % of GOCI AOD, 33 % of VIIRS Intermediate Product (IP) AOD, 26 % of Terra MODIS C6 3 km AOD, and 16 % of Aqua MODIS C6 3 km AOD fell within the reference expected error (EE) envelope (±0.05 ± 0.15 AOD). Comparing against AERONET AOD over the Japan-South Korea region, 64 % of EDR, 37 % of IP, 61 % of GOCI, 39 % of Terra MODIS, and 56 % of Aqua MODIS C6 3 km AOD fell within the EE. In general, satellite aerosol products performed better in tracking the day-to-day variability than tracking the spatial variability at high resolutions. The VIIRS EDR and GOCI products provided the most accurate AOD retrievals, while VIIRS IP and MODIS C6 3 km products had positive biases.

  11. Intercomparison of Aerosol Optical Thickness Derived from MODIS and in Situ Ground Datasets over Jaipur, a Semi-arid Zone in India.

    Science.gov (United States)

    Payra, Swagata; Soni, Manish; Kumar, Anikender; Prakash, Divya; Verma, Sunita

    2015-08-01

    The first detailed seasonal validation has been carried out for the Moderate Resolution Imaging Spectroradiometer (MODIS) Terra and Aqua satellites Level 2.0 Collection Version 5.1 AOT (τMODIS) with Aerosol Robotic Network (AERONET) Level 2.0 AOT (τAERONET) for the years 2009-2012 over semi-arid region Jaipur, northwestern India. The correlation between τMODIS versus τAERONET at 550 nm is determined with different spatial and temporal size windows. The τMODIS overestimates τAERONET within a range of +0.06 ± 0.24 during the pre-monsoon (April-June) season, while it underestimates the τAERONET with -0.04 ± 0.12 and -0.05 ± 0.18 during dry (December-March) and post-monsoon (October-November) seasons, respectively. Correlation without (with) error envelope has been found for pre-monsoon at 0.71 (0.89), post-monsoon at 0.76 (0.94), and dry season at 0.78 (0.95). τMODIS is compared to τAERONET at three more ground AERONET stations in India, i.e., Kanpur, Gual Pahari, and Pune. Furthermore, the performance of MODIS Deep Blue and Aqua AOT550 nm (τDB550 nm and τAqua550 nm) with τAERONET is also evaluated for all considered sites over India along with a U.S. desert site at White Sand, Tularosa Basin, NM. The statistical results reveal that τAqua550 nm performs better over Kanpur and Pune, whereas τDB550 nm performs better over Jaipur, Gual Pahari, and White Sand High Energy Laser Systems Test Facility (HELSTF) (U.S. site). PMID:26158600

  12. The Variations and Trends of MODIS C5 & C6 Products’ Errors in the Recent Decade over the Background and Urban Areas of North China

    Directory of Open Access Journals (Sweden)

    Qi Zhang

    2016-09-01

    Full Text Available With ten-year (2004–2013 ground-based observations of Beijing Forest (BJF and Beijing City (BJC sites in North China, we validated the high-quality MODerate resolution Imaging Spectroradiometer (MODIS Collection 5 (C5 and Collection 6 (C6 Aerosol Optical Depth (AOD products’ precision and discussed the sensors degradation issues. The annual mean AOD and Angstrom exponent (α were 0.20 ± 0.02 and 0.83 ± 0.15 in the background over the past ten years, and they were 0.59 ± 0.07 and 1.13 ± 0.08 in the urban, respectively. Ground-based AOD had both slightly declining trends, with variations of 0.023 and 0.057 over the past decade in the background and urban, respectively. There were large differences among the eight kinds of MODIS AOD products (Terra vs. Aqua, C5 vs. C6, DT (Deep Target vs. DB (Deep Blue, and DTDB in the background and urban areas, but all the products’ monthly errors had larger variations in the spring and summer, and smaller ones in the autumn and winter. In the background, more than 62% of DT matchups for C5 and C6 products were within NASA’s expected error (EE envelope. In the urban, 69%~72% of C6 DB retrievals were falling within EE envelope. The new dataset named C6 DTDB had better performance in the background, whereas it overestimated by 37%~41% in the urban caused by surface reflectivity estimation error. The range of monthly average error varied from −0.21 to 0.28 in the background and from −0.63 to 0.48 in the urban. From the background to the urban areas, the retrieval errors of Terra and Aqua had slightly increased by 0.0023~0.0158 and 0.0011~0.0124 per year, respectively, which implied that the two MODIS instruments had degraded slowly.

  13. Discrepancy Between ASTER- and MODIS- Derived Land Surface Temperatures: Terrain Effects

    OpenAIRE

    Yasushi Yamaguchi; Yuanbo Liu; Yousuke Noumi

    2009-01-01

    The MODerate resolution Imaging Spectroradiometer (MODIS) and the Advanced Spaceborne Thermal Emission Reflection Radiometer (ASTER) are onboard the same satellite platform NASA TERRA. Both MODIS and ASTER offer routine retrieval of land surface temperatures (LSTs), and the ASTER- and MODIS-retrieved LST products have been used worldwide. Because a large fraction of the earth surface consists of mountainous areas, variations in elevation, terrain slope and aspect angles can cause biases in th...

  14. Uncertainty of Passive Imager Cloud Optical Property Retrievals to Instrument Radiometry and Model Assumptions: Examples from MODIS

    Science.gov (United States)

    Platnick, Steven; Wind, Galina; Meyer, Kerry; Amarasinghe, Nandana; Arnold, G. Thomas; Zhang, Zhibo; King, Michael D.

    2013-01-01

    The optical and microphysical structure of clouds is of fundamental importance for understanding a variety of cloud radiation and precipitation processes. With the advent of MODIS on the NASA EOS Terra and Aqua platforms, simultaneous global-daily 1 km retrievals of cloud optical thickness (COT) and effective particle radius (CER) are provided, as well as the derived water path (WP). The cloud product (MOD06/MYD06 for MODIS Terra and Aqua, respectively) provides separate retrieval datasets for various two-channel retrievals, typically a VISNIR channel paired with a 1.6, 2.1, and 3.7 m spectral channel. The MOD06 forward model is derived from on a homogeneous plane-parallel cloud. In Collection 5 processing (completed in 2007 with a modified Collection 5.1 completed in 2010), pixel-level retrieval uncertainties were calculated for the following non-3-D error sources: radiometry, surface spectral albedo, and atmospheric corrections associated with model analysis uncertainties (water vapor only). The latter error source includes error correlation across the retrieval spectral channels. Estimates of uncertainty in 1 aggregated (Level-3) means were also provided assuming unity correlation between error sources for all pixels in a grid for a single day, and zero correlation of error sources from one day to the next. I n Collection 6 (expected to begin in late summer 2013) we expanded the uncertainty analysis to include: (a) scene-dependent calibration uncertainty that depends on new band and detector-specific Level 1B uncertainties, (b) new model error sources derived from the look-up tables which includes sensitivities associated with wind direction over the ocean and uncertainties in liquid water and ice effective variance, (c) thermal emission uncertainties in the 3.7 m band associated with cloud and surface temperatures that are needed to extract reflected solar radiation from the total radiance signal, (d) uncertainty in the solar spectral irradiance at 3.7 m, and

  15. MODIS land data at the EROS data center DAAC

    Science.gov (United States)

    Jenkerson, C.B.; Reed, B.C.

    2001-01-01

    The US Geological Survey's (USGS) Earth Resources Observation Systems (EROS) Data Center (EDC) in Sioux Falls, SD, USA, is the primary national archive for land processes data and one of the National Aeronautics and Space Administration's (NASA) Distributed Active Archive Centers (DAAC) for the Earth Observing System (EOS). One of EDC's functions as a DAAC is the archival and distribution of Moderate Resolution Spectroradiometer (MODIS) Land Data collected from the Earth Observing System (EOS) satellite Terra. More than 500,000 publicly available MODIS land data granules totaling 25 Terabytes (Tb) are currently stored in the EDC archive. This collection is managed, archived, and distributed by EOS Data and Information System (EOSDIS) Core System (ECS) at EDC. EDC User Services support the use of MODIS Land data, which include land surface reflectance/albedo, temperature/emissivity, vegetation characteristics, and land cover, by responding to user inquiries, constructing user information sites on the EDC web page, and presenting MODIS materials worldwide.

  16. USAID Expands eMODIS Coverage for Famine Early Warning

    Science.gov (United States)

    Jenkerson, C.; Meyer, D. J.; Evenson, K.; Merritt, M.

    2011-12-01

    Food security in countries at risk is monitored by U.S. Agency for International Development (USAID) through its Famine Early Warning Systems Network (FEWS NET) using many methods including Moderate Resolution Imaging Spectroradiometer (MODIS) data processed by U.S. Geological Survey (USGS) into eMODIS Normalized Difference Vegetation Index (NDVI) products. Near-real time production is used comparatively with trends derived from the eMODIS archive to operationally monitor vegetation anomalies indicating threatened cropland and rangeland conditions. eMODIS production over Central America and the Caribbean (CAMCAR) began in 2009, and processes 10-day NDVI composites every 5 days from surface reflectance inputs produced using predicted spacecraft and climatology information at Land and Atmosphere Near real time Capability for Earth Observing Systems (EOS) (LANCE). These expedited eMODIS composites are backed by a parallel archive of precision-based NDVI calculated from surface reflectance data ordered through Level 1 and Atmosphere Archive and Distribution System (LAADS). Success in the CAMCAR region led to the recent expansion of eMODIS production to include Africa in 2010, and Central Asia in 2011. Near-real time 250-meter products are available for each region on the last day of an acquisition interval (generally before midnight) from an anonymous file transfer protocol (FTP) distribution site (ftp://emodisftp.cr.usgs.gov/eMODIS). The FTP site concurrently hosts the regional historical collections (2000 to present) which are also searchable using the USGS Earth Explorer (http://edcsns17.cr.usgs.gov/NewEarthExplorer). As eMODIS coverage continues to grow, these geographically gridded, georeferenced tagged image file format (GeoTIFF) NDVI composites increase their utility as effective tools for operational monitoring of near-real time vegetation data against historical trends.

  17. Mapping Africa Biomass with MODIS Imagery

    Science.gov (United States)

    Laporte, N.; Baccini, A.; Houghton, R.

    2006-12-01

    Central Africa contains the second largest block of tropical forest remaining in the world, and is one of the largest carbon reservoirs on Earth. The carbon dynamics of the region differ substantially from other tropical forests because most deforestation and land use is associated with selective logging and small-scale landholders practicing traditional "slash-and-burn" agriculture. Despite estimates of 1-2 PgC/yr released to the atmosphere from tropical deforestation, the amount released from Central Africa is highly uncertain relative to the amounts released from other tropical forest areas. The uncertainty in carbon fluxes results from inadequate estimates of both rates of deforestation and standing stocks of carbon (forest biomass). Here we present new results mapping above-ground forest biomass for tropical Africa using machine learning techniques to integrate MODIS 1km spectral reflectance with forest inventory measurements to calibrate an empirical relationship. The derived forest biomass at each MODIS pixel shows the spatial distribution of forest biomass over the entire tropical forest region. The model has been tested in Uganda, Mali and part of Republic of Congo where field data were available. The regression tree model based on MODIS NBAR surface reflectance for Uganda, Mali and Republic of Congo explains 94 percent of the variance in above-ground biomass with a root mean square error (RMSE) of 27 Tons/ha. The approach shows promise for use of optical remote sensing data in mapping the spatial distribution of forest biomass across the region.

  18. Retrieval of Cirrus Cloud Optical Depth under Day and Night Conditions from MODIS Collection 6 Cloud Property Data

    Directory of Open Access Journals (Sweden)

    Andrew K. Heidinger

    2015-06-01

    Full Text Available This paper presents a technique to generate cirrus optical depth and particle effective size estimates from the cloud emissivities at 8.5, 11 and 12 μm contained in the Collection-6 (C6 MYD06 cloud product. This technique employs the latest scattering models and scattering radiative transfer approximations to estimate cloud optical depth and particle effective size using efficient analytical formulae. Two scattering models are tested. The first is the same scattering model as that used in the C6 MYD06 solar reflectance products. The second model is an empirical model derived from radiometric consistency. Both models are shown to generate optical depths that compare well to those from constrained CALIPSO retrievals and MYD06. In terms of effective radius retrievals, the results from the radiometric empirical model agree more closely with MYD06 than those from the C6 model. This analysis is applied to AQUA/MODIS data collocated with CALIPSO/CALIOP during January 2010.

  19. Comparison of the Calibration Algorithms and SI Traceability of MODIS, VIIRS, GOES, and GOES-R ABI Sensors

    Directory of Open Access Journals (Sweden)

    Raju Datla

    2016-02-01

    Full Text Available The radiometric calibration equations for the thermal emissive bands (TEB and the reflective solar bands (RSB measurements of the earth scenes by the polar satellite sensors, (Terra and Aqua MODIS and Suomi NPP (VIIRS, and geostationary sensors, GOES Imager and the GOES-R Advanced Baseline Imager (ABI are analyzed towards calibration algorithm harmonization on the basis of SI traceability which is one of the goals of the NOAA National Calibration Center (NCC. One of the overarching goals of NCC is to provide knowledge base on the NOAA operational satellite sensors and recommend best practices for achieving SI traceability for the radiance measurements on-orbit. As such, the calibration methodologies of these satellite optical sensors are reviewed in light of the recommended practice for radiometric calibration at the National Institute of Standards and Technology (NIST. The equivalence of some of the spectral bands in these sensors for their end products is presented. The operational and calibration features of the sensors for on-orbit observation of radiance are also compared in tabular form. This review is also to serve as a quick cross reference to researchers and analysts on how the observed signals from these sensors in space are converted to radiances.

  20. Towards identification of relevant variables in the observed aerosol optical depth bias between MODIS and AERONET observations

    Science.gov (United States)

    Malakar, N. K.; Lary, D. J.; Gencaga, D.; Albayrak, A.; Wei, J.

    2013-08-01

    Measurements made by satellite remote sensing, Moderate Resolution Imaging Spectroradiometer (MODIS), and globally distributed Aerosol Robotic Network (AERONET) are compared. Comparison of the two datasets measurements for aerosol optical depth values show that there are biases between the two data products. In this paper, we present a general framework towards identifying relevant set of variables responsible for the observed bias. We present a general framework to identify the possible factors influencing the bias, which might be associated with the measurement conditions such as the solar and sensor zenith angles, the solar and sensor azimuth, scattering angles, and surface reflectivity at the various measured wavelengths, etc. Specifically, we performed analysis for remote sensing Aqua-Land data set, and used machine learning technique, neural network in this case, to perform multivariate regression between the ground-truth and the training data sets. Finally, we used mutual information between the observed and the predicted values as the measure of similarity to identify the most relevant set of variables. The search is brute force method as we have to consider all possible combinations. The computations involves a huge number crunching exercise, and we implemented it by writing a job-parallel program.

  1. An Overview of the Earth Observing System Moderate Resolution Imaging Spectroradiometer (MODIS) Data Products and Availability for Environmental Applications and Global Change Studies

    Science.gov (United States)

    Salomonson, V. V.

    2003-01-01

    The Moderate Resolution Imaging Spectroradiometer (MODIS) on the Earth Observing System (EOS) Terra Mission began to produce data in February 2000. The Terra MODIS is in a sun-synchronous orbit going north to south in the daylight portion of the orbit crossing the equator at about 1030 hours local time. The spacecraft, instrument, and data systems are performing well and are producing a wide variety of data products useful for scientific and applications studies in relatively consistent fashion extending from November 2000 to the present. Within the approximately 40 MODIS data products, several are new and represent powerful and exciting capabilities such the ability to provide observations over the globe of fire occurrences, microphysical properties of clouds and sun-stimulated fluorescence from phytoplankton in the surface waters of the ocean. The remainder of the MODIS products exceeds or, at a minimum, matches the capabilities of products from heritage sensors such as, for example, the Advanced Very High Resolution Radiometer (AVHRR). Efforts are underway to provide data sets for the greater Earth science community and to improve access to these products at the various Distributed Active Archive Centers (DAACs) or through Direct Broadcast (DB) stations. The EOS Aqua mission was launched successfully May 4,2002 with another MODIS on it. The Aqua spacecraft operates in a sun-synchronous orbit going south to north in the daylight portion of the orbit crossing the equator at approximately 1330 hours local time. Subsequently the Aqua MODIS observations will substantially add to the capabilities of the Terra MODIS for environmental applications and global change studies.

  2. An Overview of the Earth Observing System Moderate Resolution Imaging Spectroradiometer (MODIS) Data Products Status and Availability for Environmental Applications and Global Change Studies

    Science.gov (United States)

    Salomonson, Vincent V.; Houser, Paul (Technical Monitor)

    2002-01-01

    The Moderate Resolution Imaging Spectroradiometer (MODIS) on the Earth Observing System (EOS) Terra Mission began to produce data in February 2000. The Terra MODIS is in a sun-synchronous orbit going north to south in the daylight portion of the orbit crossing the equator at about 1030 hours local time. The spacecraft, instrument, and data systems are performing well and are producing a wide variety of data products useful for scientific and applications studies in relatively consistent fashion extending from November 2000 to the present. Within the approximately 40 MODIS data products, several are new and represent powerful and exciting capabilities such the ability to provide observations over the globe of fire occurrences, microphysical properties of clouds and sun-stimulated fluorescence from phytoplankton in the surface waters of the ocean. The remainder of the MODIS products exceed or, at a minimum, match the capabilities of products from heritage sensors such as, for example, the Advanced Very High Resolution Radiometer (AVHRR). Efforts are underway to provide data sets for the greater Earth science community and to improve access to these products at the various Distributed Active Archive Centers (DAAC's) or through Direct Broadcast (DB) stations. The MODIS instrument on the EOS Aqua mission should also be expected to be in orbit and functioning in the Spring of 2002. The Aqua spacecraft will operate in a sun-synchronous orbit going south to north in the daylight portion of the orbit crossing the equator at approximately 1330 hours local time. Subsequently the Aqua MODIS observations will substantially add to the capabilities of the Terra MODIS for environmental applications and global change studies.

  3. MODIS Hotspot Validation over Thailand

    OpenAIRE

    Veerachai Tanpipat; Prayoonyong Nuchaiya; Kiyoshi Honda

    2009-01-01

    To ensure remote sensing MODIS hotspot (also known as active fire products or hotspots) quality and precision in forest fire control and management in Thailand, an increased level of confidence is needed. Accuracy assessment of MODIS hotspots utilizing field survey data validation is described. A quantitative evaluation of MODIS hotspot products has been carried out since the 2007 forest fire season. The carefully chosen hotspots were scattered throughout the country and within the protected ...

  4. Improvement of aerosol optical depth retrieval from MODIS spectral reflectance over the global ocean using new aerosol models archived from AERONET inversion data and tri-axial ellipsoidal dust database data

    Directory of Open Access Journals (Sweden)

    J. Lee

    2011-12-01

    Full Text Available New over-ocean aerosol models are developed by integrating extensive AERONET inversion data and a database of the optical properties of tri-axial ellipsoidal dust particles. These models allow more accurate retrieval of aerosol optical depth (AOD from the Moderate Resolution Imaging Spectroradiometer (MODIS for high AOD cases. Spectral AOD, single scattering albedo (SSA, and phase function, which are used to calculate a lookup table (LUT, are archived by combining inversion data from Aerosol Robotic Network (AERONET Sun/sky radiometers and single-scattering properties from the tri-axial ellipsoidal dust database. The aerosol models are categorized from the AERONET data using the fine-mode fraction (FMF at 550 nm and the SSA at 440 nm to resolve a variety of aerosol types throughout the globe. For each aerosol model, the changes in aerosol optical properties (AOP are included as functions of AOD. Comparisons of AODs between AERONET and MODIS for the period from 2003 to 2010 show that the new aerosol models improve correlation compared to the MODIS Collection 5 products with a Pearson coefficient of 0.93 and a regression slope of 0.99 compared to 0.92 and 0.85, respectively, for the MODIS operational algorithm. Moreover, use of the new algorithms increases the percentage of data within an expected error of ± (0.03 + 0.05 × AOD from 62 to 64% overall and from 39 to 51% for high AOD cases (AOD > 0.3. Errors in the retrieved AOD are characterized further with respect to the Ångström exponent (AE, scattering angle (Θ, and air mass factor (AMF. Overall, the new aerosol models reduce systematic errors in AOD retrieval compared with the Collection 5 data due to realistic AOP assumptions. In particular, the scattering angle dependence of the retrieved AOD for dust cases is significantly mitigated due to improved treatment of the nonsphericity of dust particles by the new algorithm.

  5. Analysis of co-located MODIS and CALIPSO observations near clouds

    Directory of Open Access Journals (Sweden)

    T. Várnai

    2012-02-01

    Full Text Available This paper aims at helping synergistic studies in combining data from different satellites for gaining new insights into two critical yet poorly understood aspects of anthropogenic climate change, aerosol-cloud interactions and aerosol radiative effects. In particular, the paper examines the way cloud information from the MODIS (MODerate resolution Imaging Spectroradiometer imager can refine our perceptions based on CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization lidar measurements about the systematic aerosol changes that occur near clouds.

    The statistical analysis of a yearlong dataset of co-located global maritime observations from the Aqua and CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation satellites reveals that MODIS's multispectral imaging ability can greatly help the interpretation of CALIOP observations. The results show that imagers on Aqua and CALIPSO yield very similar pictures, and that the discrepancies – due mainly to wind drift and differences in view angle – do not significantly hinder aerosol measurements near clouds. By detecting clouds outside the CALIOP track, MODIS reveals that clouds are usually closer to clear areas than CALIOP data alone would suggest. The paper finds statistical relationships between the distances to clouds in MODIS and CALIOP data, and proposes a rescaling approach to statistically account for the impact of clouds outside the CALIOP track even when MODIS cannot reliably detect low clouds, for example at night or over sea ice. Finally, the results show that the typical distance to clouds depends on both cloud coverage and cloud type, and accordingly varies with location and season. In maritime areas perceived cloud free, the global median distance to clouds below 3 km altitude is in the 4–5 km range.

  6. Analysis of co-located MODIS and CALIPSO observations near clouds

    Science.gov (United States)

    Várnai, T.; Marshak, A.

    2012-02-01

    This paper aims at helping synergistic studies in combining data from different satellites for gaining new insights into two critical yet poorly understood aspects of anthropogenic climate change, aerosol-cloud interactions and aerosol radiative effects. In particular, the paper examines the way cloud information from the MODIS (MODerate resolution Imaging Spectroradiometer) imager can refine our perceptions based on CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) lidar measurements about the systematic aerosol changes that occur near clouds. The statistical analysis of a yearlong dataset of co-located global maritime observations from the Aqua and CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation) satellites reveals that MODIS's multispectral imaging ability can greatly help the interpretation of CALIOP observations. The results show that imagers on Aqua and CALIPSO yield very similar pictures, and that the discrepancies - due mainly to wind drift and differences in view angle - do not significantly hinder aerosol measurements near clouds. By detecting clouds outside the CALIOP track, MODIS reveals that clouds are usually closer to clear areas than CALIOP data alone would suggest. The paper finds statistical relationships between the distances to clouds in MODIS and CALIOP data, and proposes a rescaling approach to statistically account for the impact of clouds outside the CALIOP track even when MODIS cannot reliably detect low clouds, for example at night or over sea ice. Finally, the results show that the typical distance to clouds depends on both cloud coverage and cloud type, and accordingly varies with location and season. In maritime areas perceived cloud free, the global median distance to clouds below 3 km altitude is in the 4-5 km range.

  7. The Collection 6 MODIS aerosol products over land and ocean

    Directory of Open Access Journals (Sweden)

    R. C. Levy

    2013-01-01

    Full Text Available The twin Moderate Imaging resolution Spectroradiometer (MODIS sensors have been flying on Terra since 2000 and Aqua since 2002, creating an incredible dataset of global Earth observations. Here, we introduce the Collection 6 (C6 algorithm to retrieve aerosol optical depth (AOD and aerosol size parameters from MODIS-observed spectral reflectance. While not a major overhaul from the previous Collection 5 (C5 version, there are enough changes that there is significant impact on the products and their interpretation. The C6 algorithm is comprised of three sub-algorithms for retrieving aerosol properties (1 over ocean (dark in visible and near-IR wavelengths, (2 over vegetated/dark-soiled land (dark in the visible and (3 over desert/arid land (bright in the visible. Here, we focus on the changes to both "dark target" algorithms (#1 and #2; DT-ocean and DT-land. Affecting both DT algorithms, we have updated assumptions for central wavelengths, Rayleigh optical depths and gas (H2O, O3, CO2, etc. absorption corrections, and relaxed the solar zenith angle limit (up to ≤ 84° to increase pole-ward coverage. For DT-land, we have updated the cloud mask to allow heavy smoke retrievals, fine-tuned the assignments for aerosol type as function of season/location, corrected bugs in the Quality Assurance (QA logic, and added diagnostic parameters such topographic altitude. For DT-ocean, improvements include a revised cloud mask for thin-cirrus detection, inclusion of wind speed dependence in the retrieval, updates to logic of QA Confidence flag (QAC assignment, and additions of important diagnostic information. All together, the changes to the DT algorithms result in reduced global AOD (by 0.02 over ocean and increased AOD (by 0.01 over land, along with some changes in spatial coverage. Preliminary validation shows that compared to surface-based sunphotometer data, the C6 DT-products should compare at least as well as those from

  8. MODIS snow cover mapping accuracy in small mountain catchment – comparison between open and forest sites

    Directory of Open Access Journals (Sweden)

    J. Parajka

    2012-03-01

    Full Text Available Numerous global and regional validation studies examined MODIS snow mapping accuracy by using measurements at climate stations, which are mainly at grassy sites. MODIS accuracy in alpine and forested regions is, however, still not well understood. The main objective of this study is to evaluate MODIS (MOD10A1 and MYD10A1 snow cover products in a small experimental catchment by using extensive snow course measurements at open and forest sites. The MODIS accuracy is tested in the Jalovecky creek catchment (Northern Slovakia in the period 2000–2011. The results show that the combined Terra and Aqua images enables snow mapping to an overall accuracy of 91.5%. The accuracy at forested, open and mixed land uses at the Červenec sites is 92.7%, 98.3% and 81.8%, respectively. The use of a 2-day temporal filter enables a significant reduction in the number of days with cloud coverage and an increase in overall snow mapping accuracy. In total, the 2-day temporal filter decreases the number of cloudy days from 61% to 26% and increases the snow mapping accuracy to 94%. The results indicate three possible factors leading to misclassification of snow as land: patchy snow cover, limited MODIS geolocation accuracy and mapping algorithm errors. Out of a total of 27 misclassification cases, patchy snow cover, geolocation issues and mapping errors occur in 12, 12 and 3 cases, respectively.

  9. Multilayer Cloud Detection with the MODIS Near-Infrared Water Vapor Absorption Band

    Science.gov (United States)

    Wind, Galina; Platnick, Steven; King, Michael D.; Hubanks, Paul A,; Pavolonis, Michael J.; Heidinger, Andrew K.; Yang, Ping; Baum, Bryan A.

    2009-01-01

    Data Collection 5 processing for the Moderate Resolution Imaging Spectroradiometer (MODIS) onboard the NASA Earth Observing System EOS Terra and Aqua spacecraft includes an algorithm for detecting multilayered clouds in daytime. The main objective of this algorithm is to detect multilayered cloud scenes, specifically optically thin ice cloud overlying a lower-level water cloud, that presents difficulties for retrieving cloud effective radius using single layer plane-parallel cloud models. The algorithm uses the MODIS 0.94 micron water vapor band along with CO2 bands to obtain two above-cloud precipitable water retrievals, the difference of which, in conjunction with additional tests, provides a map of where multilayered clouds might potentially exist. The presence of a multilayered cloud results in a large difference in retrievals of above-cloud properties between the CO2 and the 0.94 micron methods. In this paper the MODIS multilayered cloud algorithm is described, results of using the algorithm over example scenes are shown, and global statistics for multilayered clouds as observed by MODIS are discussed. A theoretical study of the algorithm behavior for simulated multilayered clouds is also given. Results are compared to two other comparable passive imager methods. A set of standard cloudy atmospheric profiles developed during the course of this investigation is also presented. The results lead to the conclusion that the MODIS multilayer cloud detection algorithm has some skill in identifying multilayered clouds with different thermodynamic phases

  10. Ocean Surface Current Vectors from MODIS Terra/Aqua Sea Surface Temperature Image Pairs Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Satellites that record imagery of the same sea surface area, at times separated by a few hours, can be used to estimate ocean surface velocity fields based on the...

  11. Status of Terra MODIS Operation, Calibration, and Performance

    Science.gov (United States)

    Xiong, X.; Wenny, B.; Wu, A.; Angal, A.; Geng, X.; Chen, H.; Dodd, J.; Link, D.; Madhavan, S.; Chen, N.; Li, Y.; Iacangelo, S.; Barnes, W.; Salomonson, V.

    2014-01-01

    Since launch in December 1999, Terra MODIS has successfully operated for nearly 15 years, making continuous observations. Data products derived from MODIS observations have significantly contributed to a wide range of studies of key geophysical parameters of the earth's eco-system of land, ocean, and atmosphere, and their changes over time. The quality of MODIS data products relies on the dedicated effort to monitor and sustain instrument health and operation, to calibrate and update sensor parameters and properties, and to improve calibration algorithms. MODIS observations are made in 36 spectral bands, covering wavelengths from visible to long-wave infrared. The reflective solar bands (1-19 and 26) are primarily calibrated by a solar diffuser (SD) panel and regularly scheduled lunar observations. The thermal emissive bands (20-25 and 27- 36) calibration is referenced to an on-board blackbody (BB) source. On-orbit changes in the sensor spectral and spatial characteristics are monitored by a spectroradiometric calibration assembly (SRCA). This paper provides an overview of Terra MODIS on-orbit operation and calibration activities and implementation strategies. It presents and summarizes sensor on-orbit performance using nearly 15 years of data from its telemetry, on-board calibrators, and lunar observations. Also discussed in this paper are changes in sensor characteristics, corrections applied to maintain MODIS level 1B (L1B) data quality, and efforts for future improvements.

  12. Application of MODIS Products to Infer Possible Relationships Between Basin Land Cover and Coastal Waters Turbidity Using the Magdalena River, Colombia, as a Case Study

    Science.gov (United States)

    Madrinan, Max Jacobo Moreno; Cordova, Africa Flores; Olivares, Francisco Delgado; Irwin, Dan

    2012-01-01

    Basin development and consequent change in basin land cover have been often associated with an increased turbidity in coastal waters because of sediment yield and nutrients loading. The later leads to phytoplankton abundance further exacerbating water turbidity. This subsequently affects biological and physical processes in coastal estuaries by interfering with sun light penetration to coral reefs and sea grass, and even affecting public health. Therefore, consistent estimation of land cover changes and turbidity trend lines is crucial to design environmental and restoration management plans, to predict fate of possible pollutants, and to estimate sedimentary fluxes into the ocean. Ground solely methods to estimate land cover change would be unpractical and traditional methods of monitoring in situ water turbidity can be very expensive and time consuming. Accurate monitoring on the status and trends of basin land cover as well as the water quality of the receiving water bodies are required for analysis of relationships between the two variables. Use of remote sensing (RS) technology provides a great benefit for both fields of study, facilitating monitoring of changes in a timely and cost effective manner and covering wide areas with long term measurements. In this study, the Magdalena River basin and fixed geographical locations in the estuarine waters of its delta are used as a case to study the temporal trend lines of both, land cover change and the reflectance of the water turbidity using satellite technology. Land cover data from a combined product between sensors Terra and Aqua (MCD12Q1) from MODIS will be adapted to the conditions in the Magdalena basin to estimate changes in land cover since year 2000 to 2009. Surface reflectance data from a MODIS, Terra (MOD09GQ), band 1, will be used in lieu of in situ water turbidity for the time period between 2000 and present. Results will be compared with available existing data.

  13. Ground based measurements on reflectance towards validating atmospheric correction algorithms on IRS-P6 AWiFS data

    Science.gov (United States)

    Rani Sharma, Anu; Kharol, Shailesh Kumar; Kvs, Badarinath; Roy, P. S.

    aggregated ground measurements which showed a very good correlation of 0.96 in all four spectral bands (i.e. green, red, NIR and SWIR). In order to quantify the accuracy of the proposed method in the estimation of the surface reflectance, the root mean square error (RMSE) associated to the proposed method was evaluated. The analysis of the ground measured versus retrieved AWiFS reflectance yielded smaller RMSE values in case of all four spectral bands. EOS TERRA/AQUA MODIS derived AOD exhibited very good correlation of 0.92 and the data sets provides an effective means for carrying out atmospheric corrections in an operational way. Keywords: Atmospheric correction, 6S code, MODIS, Spectroradiometer, Sun-Photometer

  14. The shortwave radiative forcing bias of liquid and ice clouds from MODIS observations

    Directory of Open Access Journals (Sweden)

    L. Oreopoulos

    2009-08-01

    Full Text Available We present an assessment of the plane-parallel bias of the shortwave cloud radiative forcing (SWCRF of liquid and ice clouds at 1 deg scales using global MODIS (Terra and Aqua cloud optical property retrievals for four months of the year 2005 representative of the meteorological seasons. The (negative bias is estimated as the difference of SWCRF calculated using the Plane-Parallel Homogeneous (PPH approximation and the Independent Column Approximation (ICA. PPH calculations use MODIS-derived gridpoint means while ICA calculations use distributions of cloud optical thickness and effective radius. Assisted by a broadband solar radiative transfer algorithm, we find that the absolute value of global SWCRF bias of liquid clouds at the top of the atmosphere is about 6 W m−2 for MODIS overpass times while the SWCRF bias for ice clouds is smaller in absolute terms by about 0.7 W m−2, but with stronger spatial variability. If effective radius variability is neglected and only optical thickness horizontal variations are accounted for, the absolute SWCRF biases increase by about 0.3–0.4 W m−2 on average. Marine clouds of both phases exhibit greater (more negative SWCRF biases than continental clouds. Finally, morning (Terra–afternoon (Aqua differences in SWCRF bias are much more pronounced for ice clouds, up to about 15% (Aqua producing stronger negative bias on global scales, with virtually all contribution to the difference coming from land areas. The substantial magnitude of the global SWCRF bias, which for clouds of both phases is collectively about 4 W m−2 for diurnal averages, should be considered a strong motivation for global climate modelers to accelerate efforts linking cloud schemes capable of subgrid condensate variability with appropriate radiative transfer schemes.

  15. Improvement of aerosol optical depth retrieval from MODIS spectral reflectance over the global ocean using new aerosol models archived from AERONET inversion data and tri-axial ellipsoidal dust database

    Directory of Open Access Journals (Sweden)

    J. Lee

    2012-08-01

    Full Text Available New over-ocean aerosol models are developed by integrating the inversion data from the Aerosol Robotic Network (AERONET sun/sky radiometers with a database for the optical properties of tri-axial ellipsoid particles. The new aerosol models allow more accurate retrieval of aerosol optical depth (AOD from the Moderate Resolution Imaging Spectroradiometer (MODIS in the case of high AOD (AOD > 0.3. The aerosol models are categorized by using the fine-mode fraction (FMF at 550 nm and the single-scattering albedo (SSA at 440 nm from the AERONET inversion data to include a variety of aerosol types found around the globe. For each aerosol model, the changes in the aerosol optical properties (AOPs as functions of AOD are considered to better represent aerosol characteristics. Comparisons of AODs between AERONET and MODIS for the period from 2003 to 2010 show that the use of the new aerosol models enhances the AOD accuracy with a Pearson coefficient of 0.93 and a regression slope of 0.99 compared to 0.92 and 0.85 calculated using the MODIS Collection 5 data. Moreover, the percentage of data within an expected error of ± (0.03 + 0.05 × AOD is increased from 62% to 64% for overall data and from 39% to 5% for AOD > 0.3. Errors in the retrieved AOD are further characterized with respect to the Ångström exponent (AE, scattering angle (Θ, SSA, and air mass factor (AMF. Due to more realistic AOPs assumptions, the new algorithm generally reduces systematic errors in the retrieved AODs compared with the current operational algorithm. In particular, the underestimation of fine-dominated AOD and the scattering angle dependence of dust-dominated AOD are significantly mitigated as results of the new algorithm's improved treatment of aerosol size distribution and dust particle nonsphericity.

  16. Antihyperlipidemic and antioxidant effects of Samhwangsasimtang aqua-acupuncture

    Directory of Open Access Journals (Sweden)

    Lee Eun

    2005-02-01

    Full Text Available Effects of Samhwangsasimtang aqua-acupuncture at gansoo(B18 and chungwan(CV12 on antihyperlipidemic and antioxidant were investigated in rat fed high fat diet. Concentrations of triglyceride, free fatty acids, lipoprotein and glucose in plasma showed a tendency to decrease in the aqua-acupuncture groups. In plasma lipid composition, total cholesterol and LDL- cholesterol showed a tendency to decrease in aqua-acupuncture groups, however the values of HDL-cholesterol showed no significantly different in the treatment groups. Concentration of thiobarbituric acid reactive substances(TBARS in plasma and liver showed a low in the aqua-acupuncture groups. The values of glutathione peroxidase(GSH-Px and catalase(CAT activity showed a tendency to increase in aqua-acupuncture groups. However the values of superoxide dismutase(SOD activity showed no significantly different in the treatment groups.

  17. Visual Modeling for Aqua Ventus I off Monhegan Island, ME

    Energy Technology Data Exchange (ETDEWEB)

    Hanna, Luke A.; Whiting, Jonathan M.; Copping, Andrea E.

    2013-11-27

    To assist the University of Maine in demonstrating a clear pathway to project completion, PNNL has developed visualization models of the Aqua Ventus I project that accurately depict the Aqua Ventus I turbines from various points on Monhegain Island, ME and the surrounding area. With a hub height of 100 meters, the Aqua Ventus I turbines are large and may be seen from many areas on Monhegan Island, potentially disrupting important viewsheds. By developing these visualization models, which consist of actual photographs taken from Monhegan Island and the surrounding area with the Aqua Ventus I turbines superimposed within each photograph, PNNL intends to support the project’s siting and permitting process by providing the Monhegan Island community and various other stakeholders with a probable glimpse of how the Aqua Ventus I project will appear.

  18. Geomorphology of MODIS-Visible Dust Plumes in the Chihuahuan Desert - Preliminary Results

    Science.gov (United States)

    Gill, T. E.; Mbuh, M. J.; Dominguez, M. A.; Lee, J. A.; Baddock, M. C.; Lee, C. E.; Whitehead, S. C.; Rivera Rivera, N. I.; Peinado, P.

    2009-12-01

    We identified 28 days since 2001 when blowing dust impacted El Paso, Texas and dust plumes were visible on NASA MODIS Terra/Aqua satellite images in the surrounding Chihuahuan Desert. Initiation points of >270 individual plumes were located on the MODIS images. Land use/land cover for each point was determined by field work, aerial photography, and/or soil/geological maps, and points were assigned to the geomorphic classes proposed by Bullard et al. (this session). Although dust plume identification is subjective (weak plumes, plumes obscured by clouds, and plumes occurring when the satellites are not overhead will be missed), these data provide preliminary information on the relationship between geomorphology and the initiation of major dust storms in the Chihuahuan Desert. Ephemeral lakes and alluvial low-relief non-incised lands are roughly equal producers of satellite-visible dust plumes in the Chihuahuan Desert. Anthropogenic modification of alluvial floodplains for cropping (primarily in the Casas Grandes and Del Carmen river basins) impacts dust generation, since about 2/3 of alluvial low-relief sites show evidence of agriculture. These agricultural fields are generally fallow during the November- April windy season. Not including agricultural lands, playas represent ~2x the number of sources as low-relief alluvial deposits. Aeolian sand deposits (predominantly coppice dunes and sand sheets overlaying alluvial or lacustrine sediments) account for about 1/7 of the points. These sands may act as erosional agents, providing saltating particles for sandblasting and bombardment of other sediments exposed nearby. Edges of ephemeral lakes are proportionally important sources (~10% of the points), likely due to the convergence of saltating sand, fine lacustrine sediments, and low roughness lengths of playa surfaces. Alluvial fans and alluvial uplands are minor dust sources compared to their overall prevalence in the region. Gobi/gibber/stony deposits are known dust

  19. Modeling GPP in the Nordic forest landscape with MODIS time series data—Comparison with the MODIS GPP product

    DEFF Research Database (Denmark)

    Schubert, Per; Lagergren, Fredrik; Aurela, Mika;

    2012-01-01

    . The main objective of this study was to investigate if MODIS 500m reflectance data can be used to drive empirical models for regional estimations of GPP in Nordic forests. The performance of the proposed models was compared with the MODIS 1km GPP product. Linear regression analyses were made on 8-day...... averages of eddy covariance GPP from three deciduous and ten coniferous sites in relation to MODIS 8-day composite data and 8-day averages of modeled incoming PPFD (photosynthetic photon flux density). Time series of EVI2 (two-band enhanced vegetation index) were calculated from MODIS 500m reflectance data...... and smoothed by a curve fitting procedure. For most sites, GPP was fairly strongly to strongly related to the product of EVI2 and PPFD (Deciduous: R2=0.45–0.86, Coniferous: R2=0.49–0.90). Similar strengths were found between GPP and the product of EVI2 and MODIS 1km daytime LST (land surface temperature) (R2...

  20. Comportamiento y análisis de descriptores de texturas en imágenes MODIS

    OpenAIRE

    Ruiz Alonso, Ángel

    2011-01-01

    En este trabajo se realiza un estudio sobre la efectividad de varios descriptores de textura en imágenes, que han sido utilizados exitosamente en imágenes obtenidas con dispositivos de captura dentro del espectro visible. Se propone el estudio de esos mismos descriptores para el análisis de imágenes obtenidas por medio de la plataforma MODIS (Moderate Resolution Imaging Spectroradiometer), instalada a bordo de dos satélites espaciales, Terra y Aqua de la NASA. Dado el vuelo periódico de lo...

  1. ATMOSPHERIC AEROSOL VARIABILITY OVER THE REGION OF SAN PEDRO MÁRTIR FROM MODIS DATA

    OpenAIRE

    Mario R. Araiza Quijano; Irene Cruz-González

    2011-01-01

    Se presenta un estudio del espesoróptico del aerosol atmosférico (AOT por sus siglas en inglés) en el sitio astronómico de San Pedro Mártir, B. C., México durante el periodo 2000-2008. Las mediciones del AOT se realizaron con el instrumento Moderate Resolution Imaging Spectroradiometer (MODIS), a bordo de los satélites Aqua y Terra de la NASA. Se han identificado valores característicos estacionales que muestran un comportamiento de mayor transparencia atmosférica durante el otoño. Las mejore...

  2. Local validation of MODIS sensor sea surface temperature on western Mediterranean shallow waters

    OpenAIRE

    E. Durá; Mendiguren, G.; Martín, M.P.; Acevedo-Dudley, M.J.; M. Bosch-Bolmar; Fuentes, V.L.; Bordehore, C.

    2014-01-01

    [ES] La temperatura superficial del mar (SST) estimada a partir de los productos 11  μm diurnos y nocturnos y 4 μm nocturnos del sensor MODIS (Moderate Resolution Imaging Spectroradiometer) a bordo de la plataforma Aqua, han sido comparados con datos medidos in situ a tres profundidades diferentes (15, 50 y 100 cm) en una zona costera del Mediterráneo Occidental. Esta comparación ha permitido analizar la incertidumbre que existe en la estimación de este parámetro en aguas someras y próxima...

  3. Investigating the impact of haze on cloud detection of passive satellite by comparing MODIS, CloudSat and CALIPSO

    Science.gov (United States)

    Gong, W.; Mao, F.

    2015-12-01

    The cloud detection algorithm for passive sensors is usually based on a fuzzy logic system with thresholds determined from previous observations. In recent years, haze and high aerosol concentrations with high AOD occur frequently in China and may critically impact the accuracy of the MODIS cloud detection. Thus, we comprehensively explore this impact by comparing the results from MODIS/Aqua (passive sensor), CALIOP/CALIPSO (lidar sensor), and CPR/CloudSat (microwave sensor) of the A-Train suite of instruments using an averaged AOD as an index for an aerosol concentration value. Case studies concerning the comparison of the three sensors indicate that MODIS cloud detection is reduced during haze events. In addition, statistical studies show that an increase in AOD creates an increase in the percentage of uncertain flags and a decrease in hit rate, a consistency index between consecutive sets of cloud retrievals. Therefore, we can conclude that the ability of MODIS cloud detection is weakened by large concentrations of aerosols. This suggests that use of the MODIS cloud mask, and derived higher level products, in situations with haze requires caution. Further improvement of this retrieval algorithm, is desired as haze studies based on MODIS products are of great interest in a number of related fields.

  4. An Examination of the Nature of Global MODIS Cloud Regimes

    Science.gov (United States)

    Oreopoulos, Lazaros; Cho, Nayeong; Lee, Dongmin; Kato, Seiji; Huffman, George J.

    2014-01-01

    We introduce global cloud regimes (previously also referred to as "weather states") derived from cloud retrievals that use measurements by the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument aboard the Aqua and Terra satellites. The regimes are obtained by applying clustering analysis on joint histograms of retrieved cloud top pressure and cloud optical thickness. By employing a compositing approach on data sets from satellites and other sources, we examine regime structural and thermodynamical characteristics. We establish that the MODIS cloud regimes tend to form in distinct dynamical and thermodynamical environments and have diverse profiles of cloud fraction and water content. When compositing radiative fluxes from the Clouds and the Earth's Radiant Energy System instrument and surface precipitation from the Global Precipitation Climatology Project, we find that regimes with a radiative warming effect on the atmosphere also produce the largest implied latent heat. Taken as a whole, the results of the study corroborate the usefulness of the cloud regime concept, reaffirm the fundamental nature of the regimes as appropriate building blocks for cloud system classification, clarify their association with standard cloud types, and underscore their distinct radiative and hydrological signatures.

  5. Ten Years of Cloud Optical and Microphysical Retrievals from MODIS

    Science.gov (United States)

    Platnick, Steven; King, Michael D.; Wind, Galina; Hubanks, Paul; Arnold, G. Thomas; Amarasinghe, Nandana

    2010-01-01

    The MODIS cloud optical properties algorithm (MOD06/MYD06 for Terra and Aqua MODIS, respectively) has undergone extensive improvements and enhancements since the launch of Terra. These changes have included: improvements in the cloud thermodynamic phase algorithm; substantial changes in the ice cloud light scattering look up tables (LUTs); a clear-sky restoral algorithm for flagging heavy aerosol and sunglint; greatly improved spectral surface albedo maps, including the spectral albedo of snow by ecosystem; inclusion of pixel-level uncertainty estimates for cloud optical thickness, effective radius, and water path derived for three error sources that includes the sensitivity of the retrievals to solar and viewing geometries. To improve overall retrieval quality, we have also implemented cloud edge removal and partly cloudy detection (using MOD35 cloud mask 250m tests), added a supplementary cloud optical thickness and effective radius algorithm over snow and sea ice surfaces and over the ocean, which enables comparison with the "standard" 2.1 11m effective radius retrieval, and added a multi-layer cloud detection algorithm. We will discuss the status of the MOD06 algorithm and show examples of pixellevel (Level-2) cloud retrievals for selected data granules, as well as gridded (Level-3) statistics, notably monthly means and histograms (lD and 2D, with the latter giving correlations between cloud optical thickness and effective radius, and other cloud product pairs).

  6. Comparing MODIS C6 'Deep Blue' and 'Dark Target' Aerosol Data

    Science.gov (United States)

    Hsu, N. C.; Sayer, A. M.; Bettenhausen, C.; Lee, J.; Levy, R. C.; Mattoo, S.; Munchak, L. A.; Kleidman, R.

    2014-01-01

    The MODIS Collection 6 Atmospheres product suite includes refined versions of both 'Deep Blue' (DB) and 'Dark Target' (DT) aerosol algorithms, with the DB dataset now expanded to include coverage over vegetated land surfaces. This means that, over much of the global land surface, users will have both DB and DT data to choose from. A 'merged' dataset is also provided, primarily for visualization purposes, which takes retrievals from either or both algorithms based on regional and seasonal climatologies of normalized difference vegetation index (NDVI). This poster present some comparisons of these two C6 aerosol algorithms, focusing on AOD at 550 nm derived from MODIS Aqua measurements, with each other and with Aerosol Robotic Network (AERONET) data, with the intent to facilitate user decisions about the suitability of the two datasets for their desired applications.

  7. Degradation nonuniformity in the solar diffuser bidirectional reflectance distribution function.

    Science.gov (United States)

    Sun, Junqiang; Chu, Mike; Wang, Menghua

    2016-08-01

    The assumption of angular dependence stability of the solar diffuser (SD) throughout degradation is critical to the on-orbit calibration of the reflective solar bands (RSBs) in many satellite sensors. Recent evidence has pointed to the contrary, and in this work, we present a thorough investigative effort into the angular dependence of the SD degradation for the Visible Infrared Imaging Radiometer Suite (VIIRS) onboard the Suomi National Polar-orbiting Partnership (SNPP) satellite and for the twin Moderate-resolution Imaging Spectroradiometer (MODIS) onboard Terra and Aqua spacecrafts. One common key step in the RSB calibration is the use of the SD degradation performance measured by an accompanying solar diffuser stability monitor (SDSM) as a valid substitute for the SD degradation factor in the direction of the RSB view. If SD degradations between these two respective directions do not maintain the same relative relationship over time, then the unmitigated use of the SDSM-measured SD degradation factor in the RSB calibration calculation will generate bias, and consequently, long-term drift in derived science products. We exploit the available history of the on-orbit calibration events to examine the response of the SDSM and the RSB detectors to the incident illumination reflecting off SD versus solar declination angle and show that the angular dependency, particularly at short wavelengths, evolves with respect to time. The generalized and the decisive conclusion is that the bidirectional reflectance distribution function (BRDF) of the SD degrades nonuniformly with respect to both incident and outgoing directions. Thus, the SDSM-based measurements provide SD degradation factors that are biased relative to the RSB view direction with respect to the SD. The analysis also reveals additional interesting phenomena, for example, the sharp behavioral change in the evolving angular dependence observed in Terra MODIS and SNPP VIIRS. For SNPP VIIRS the mitigation for this

  8. Degradation nonuniformity in the solar diffuser bidirectional reflectance distribution function.

    Science.gov (United States)

    Sun, Junqiang; Chu, Mike; Wang, Menghua

    2016-08-01

    The assumption of angular dependence stability of the solar diffuser (SD) throughout degradation is critical to the on-orbit calibration of the reflective solar bands (RSBs) in many satellite sensors. Recent evidence has pointed to the contrary, and in this work, we present a thorough investigative effort into the angular dependence of the SD degradation for the Visible Infrared Imaging Radiometer Suite (VIIRS) onboard the Suomi National Polar-orbiting Partnership (SNPP) satellite and for the twin Moderate-resolution Imaging Spectroradiometer (MODIS) onboard Terra and Aqua spacecrafts. One common key step in the RSB calibration is the use of the SD degradation performance measured by an accompanying solar diffuser stability monitor (SDSM) as a valid substitute for the SD degradation factor in the direction of the RSB view. If SD degradations between these two respective directions do not maintain the same relative relationship over time, then the unmitigated use of the SDSM-measured SD degradation factor in the RSB calibration calculation will generate bias, and consequently, long-term drift in derived science products. We exploit the available history of the on-orbit calibration events to examine the response of the SDSM and the RSB detectors to the incident illumination reflecting off SD versus solar declination angle and show that the angular dependency, particularly at short wavelengths, evolves with respect to time. The generalized and the decisive conclusion is that the bidirectional reflectance distribution function (BRDF) of the SD degrades nonuniformly with respect to both incident and outgoing directions. Thus, the SDSM-based measurements provide SD degradation factors that are biased relative to the RSB view direction with respect to the SD. The analysis also reveals additional interesting phenomena, for example, the sharp behavioral change in the evolving angular dependence observed in Terra MODIS and SNPP VIIRS. For SNPP VIIRS the mitigation for this

  9. Progress in Understanding the Impacts of 3-D Cloud Structure on MODIS Cloud Property Retrievals for Marine Boundary Layer Clouds

    Science.gov (United States)

    Zhang, Zhibo; Werner, Frank; Miller, Daniel; Platnick, Steven; Ackerman, Andrew; DiGirolamo, Larry; Meyer, Kerry; Marshak, Alexander; Wind, Galina; Zhao, Guangyu

    2016-01-01

    Theory: A novel framework based on 2-D Tayler expansion for quantifying the uncertainty in MODIS retrievals caused by sub-pixel reflectance inhomogeneity. (Zhang et al. 2016). How cloud vertical structure influences MODIS LWP retrievals. (Miller et al. 2016). Observation: Analysis of failed MODIS cloud property retrievals. (Cho et al. 2015). Cloud property retrievals from 15m resolution ASTER observations. (Werner et al. 2016). Modeling: LES-Satellite observation simulator (Zhang et al. 2012, Miller et al. 2016).

  10. Sensitivity of Marine Warm Cloud Retrieval Statistics to Algorithm Choices: Examples from MODIS Collection 6

    Science.gov (United States)

    Platnick, S.; Wind, G.; Zhang, Z.; Ackerman, S. A.; Maddux, B. C.

    2012-12-01

    The optical and microphysical structure of warm boundary layer marine clouds is of fundamental importance for understanding a variety of cloud radiation and precipitation processes. With the advent of MODIS (Moderate Resolution Imaging Spectroradiometer) on the NASA EOS Terra and Aqua platforms, simultaneous global/daily 1km retrievals of cloud optical thickness and effective particle size are provided, as well as the derived water path. In addition, the cloud product (MOD06/MYD06 for MODIS Terra and Aqua, respectively) provides separate effective radii results using the 1.6, 2.1, and 3.7 μm spectral channels. Cloud retrieval statistics are highly sensitive to how a pixel identified as being "not-clear" by a cloud mask (e.g., the MOD35/MYD35 product) is determined to be useful for an optical retrieval based on a 1-D cloud model. The Collection 5 MODIS retrieval algorithm removed pixels associated with cloud edges (defined by immediate adjacency to "clear" MOD/MYD35 pixels) as well as ocean pixels with partly cloudy elements in the 250m MODIS cloud mask - part of the so-called Clear Sky Restoral (CSR) algorithm. Collection 6 attempts retrievals for those two pixel populations, but allows a user to isolate or filter out the populations via CSR pixel-level Quality Assessment (QA) assignments. In this paper, using the preliminary Collection 6 MOD06 product, we present global and regional statistical results of marine warm cloud retrieval sensitivities to the cloud edge and 250m partly cloudy pixel populations. As expected, retrievals for these pixels are generally consistent with a breakdown of the 1D cloud model. While optical thickness for these suspect pixel populations may have some utility for radiative studies, the retrievals should be used with extreme caution for process and microphysical studies.

  11. Sensitivity of Marine Warm Cloud Retrieval Statistics to Algorithm Choices: Examples from MODIS Collection 6

    Science.gov (United States)

    Platnick, Steven; Wind, Galina; Zhang, Zhibo; Ackerman, Steven A.; Maddux, Brent

    2012-01-01

    The optical and microphysical structure of warm boundary layer marine clouds is of fundamental importance for understanding a variety of cloud radiation and precipitation processes. With the advent of MODIS (Moderate Resolution Imaging Spectroradiometer) on the NASA EOS Terra and Aqua platforms, simultaneous global/daily 1km retrievals of cloud optical thickness and effective particle size are provided, as well as the derived water path. In addition, the cloud product (MOD06/MYD06 for MODIS Terra and Aqua, respectively) provides separate effective radii results using the l.6, 2.1, and 3.7 m spectral channels. Cloud retrieval statistics are highly sensitive to how a pixel identified as being "notclear" by a cloud mask (e.g., the MOD35/MYD35 product) is determined to be useful for an optical retrieval based on a 1-D cloud model. The Collection 5 MODIS retrieval algorithm removed pixels associated with cloud'edges as well as ocean pixels with partly cloudy elements in the 250m MODIS cloud mask - part of the so-called Clear Sky Restoral (CSR) algorithm. Collection 6 attempts retrievals for those two pixel populations, but allows a user to isolate or filter out the populations via CSR pixel-level Quality Assessment (QA) assignments. In this paper, using the preliminary Collection 6 MOD06 product, we present global and regional statistical results of marine warm cloud retrieval sensitivities to the cloud edge and 250m partly cloudy pixel populations. As expected, retrievals for these pixels are generally consistent with a breakdown of the ID cloud model. While optical thickness for these suspect pixel populations may have some utility for radiative studies, the retrievals should be used with extreme caution for process and microphysical studies.

  12. Aerosol Characterisitics Over Alberta Using Modis and OMI Satellite Data

    Science.gov (United States)

    Marey, H. S.; Hashisho, Z., Sr.; Fu, L.; Gille, J. C.

    2015-12-01

    We present the first detailed analysis of optical aerosol characterization over Alberta based on satellite data analysis. Aerosol optical depth (AOD) at 550 nm for 11 years (2003-2013), derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor onboard NASA's Aqua satellite, was analyzed. Additionally, UV aerosol index (AI) data for 9 years (2005-2013) retrieved from the Ozone Monitoring Instrument (OMI) onboard NASA's Aura satellite was used to examine absorbing aerosols. Comparing AERONET to MODIS 3 km and 10 km products indicated a stronger correlation (r=0.9 for the latter vs 0.7 for the former) thus 10 km product has been utilized for this study. Overall, gridded seasonal maps (0.1 deg.) of the 11 yr averaged AOD illustrate the highest AOD during summer, followed by spring, with the lowest observed values during fall (there is no enough valid MODIS data in winter due to cloud cover). Aerosol optical properties exhibited large spatio-temporal heterogeneity in the summer with mean AOD of 0.25, followed by spring, while the fall had less variability with mean AOD below 0.1 for the entire region. However, the spatial analysis indicated hot spots around Edmonton and Calgary cities even in the fall when AODs are very low (close to background). All of the datasets showed interannual variability with no significant trend. The AI values ranged from 0.5 during winter to as high as 5 during summer suggesting mid- and long range transport of boreal fire emissions. Map correlation between AOD and UV AI showed large variability (0.2 to 0.7) indicating presence of different types of aerosols. These low correlations imply the presence of non-absorbing particles (e.g. sulfate) that comprise a relatively large mass fraction of AOD and/or low altitude particles.

  13. Improvements of VIIRS and MODIS solar diffuser and lunar calibration

    Science.gov (United States)

    Xiong, Xiaoxiong; Butler, James; Lei, Ning; Sun, Junqiang; Fulbright, Jon; Wang, Zhipeng; McIntire, Jeff; Angal, Amit

    2013-09-01

    Both VIIRS and MODIS instruments use solar diffuser (SD) and lunar observations to calibrate their reflective solar bands (RSB). A solar diffuser stability monitor (SDSM) is used to track the SD on-orbit degradation. On-orbit observations have shown similar wavelength-dependent SD degradation (larger at shorter VIS wavelengths) and SDSM detector response degradation (larger at longer NIR wavelengths) for both VIIRS and MODIS instruments. In general, the MODIS scan mirror has experienced more degradation in the VIS spectral region whereas the VIIRS rotating telescope assembly (RTA) mirrors have seen more degradation in the NIR and SWIR spectral region. Because of this wavelength dependent mirror degradation, the sensor's relative spectral response (RSR) needs to be modulated. Due to differences between the solar and lunar spectral irradiance, the modulated RSR could have different effects on the SD and lunar calibration. In this paper, we identify various factors that should be considered for the improvements of VIIRS and MODIS solar and lunar calibration and examine their potential impact. Specifically, we will characterize and assess the calibration impact due to SD and SDSM attenuation screen transmission (uncertainty), SD BRF uncertainty and onorbit degradation, SDSM detector response degradation, and modulated RSR resulting from the sensor's optics degradation. Also illustrated and discussed in this paper are the calibration strategies implemented in the VIIRS and MODIS SD and lunar calibrations and efforts that could be made for future improvements.

  14. A novel retrieval of daytime atmospheric dust and volcanic ash heights through a synergy of AIRS infrared radiances and MODIS L2 optical depths

    OpenAIRE

    DeSouza-Machado, S.; Strow, L.; E. Maddy; O. Torres; Thomas, G.; Grainger, D; Robinson, A.

    2015-01-01

    We present a novel method to retrieve daytime atmospheric dust and ash plume heights using a synergy of infrared hyper-spectral radiances and retrieved visible optical depths. The method is developed using data from the Atmospheric Infrared Sounder (AIRS) and Moderate Resolution Imaging Spectroradiometer (MODIS), both of which are on NASA's Aqua platform, and lends itself to also a χ2 height derivation based on the smallest bias between observations and ...

  15. Corrections to MODIS Terra Calibration and Polarization Trending Derived from Ocean Color Products

    Science.gov (United States)

    Meister, Gerhard; Eplee, Robert E.; Franz, Bryan A.

    2014-01-01

    Remotely sensed ocean color products require highly accurate top-of-atmosphere (TOA) radiances, on the order of 0.5% or better. Due to incidents both prelaunch and on-orbit, meeting this requirement has been a consistent problem for the MODIS instrument on the Terra satellite, especially in the later part of the mission. The NASA Ocean Biology Processing Group (OBPG) has developed an approach to correct the TOA radiances of MODIS Terra using spatially and temporally averaged ocean color products from other ocean color sensors (such as the SeaWiFS instrument on Orbview-2 or the MODIS instrument on the Aqua satellite). The latest results suggest that for MODIS Terra, both linear polarization parameters of the Mueller matrix are temporally evolving. A change to the functional form of the scan angle dependence improved the quality of the derived coefficients. Additionally, this paper demonstrates that simultaneously retrieving polarization and gain parameters improves the gain retrieval (versus retrieving the gain parameter only).

  16. Adjustments to the MODIS Terra Radiometric Calibration and Polarization Sensitivity in the 2010 Reprocessing

    Science.gov (United States)

    Meister, Gerhard; Franz, Bryan A.

    2011-01-01

    The Moderate-Resolution Imaging Spectroradiometer (MODIS) on NASA s Earth Observing System (EOS) satellite Terra provides global coverage of top-of-atmosphere (TOA) radiances that have been successfully used for terrestrial and atmospheric research. The MODIS Terra ocean color products, however, have been compromised by an inadequate radiometric calibration at the short wavelengths. The Ocean Biology Processing Group (OBPG) at NASA has derived radiometric corrections using ocean color products from the SeaWiFS sensor as truth fields. In the R2010.0 reprocessing, these corrections have been applied to the whole mission life span of 10 years. This paper presents the corrections to the radiometric gains and to the instrument polarization sensitivity, demonstrates the improvement to the Terra ocean color products, and discusses issues that need further investigation. Although the global averages of MODIS Terra ocean color products are now in excellent agreement with those of SeaWiFS and MODIS Aqua, and image quality has been significantly improved, the large corrections applied to the radiometric calibration and polarization sensitivity require additional caution when using the data.

  17. Evaluation of cloud base height measurements from Ceilometer CL31 and MODIS satellite over Ahmedabad, India

    Science.gov (United States)

    Sharma, Som; Vaishnav, Rajesh; Shukla, Munn V.; Kumar, Prashant; Kumar, Prateek; Thapliyal, Pradeep K.; Lal, Shyam; Acharya, Yashwant B.

    2016-02-01

    Clouds play a tangible role in the Earth's atmosphere and in particular, the cloud base height (CBH), which is linked to cloud type, is one of the most important characteristics to describe the influence of clouds on the environment. In the present study, CBH observations from Ceilometer CL31 were extensively studied during May 2013 to January 2015 over Ahmedabad (23.03° N, 72.54° E), India. A detailed comparison has been performed with the use of ground-based CBH measurements from Ceilometer CL31 and CBH retrieved from MODIS (Moderate Resolution Imaging Spectroradiometer) onboard Aqua and Terra satellite. CBH retrieved from MODIS is ˜ 1.955 and ˜ 1.093 km on 25 July 2014 and 1 January 2015 respectively, which matches well with ceilometer-measured CBH ( ˜ 1.92 and ˜ 1.097 km). Some interesting features of cloud dynamics viz. strong downdraft and updraft have been observed over Ahmedabad which revealed different cloud characteristics during monsoon and post-monsoon periods. CBH shows seasonal variation during the Indian summer monsoon and post-monsoon period. Results indicate that the ceilometer is an excellent instrument to precisely detect low- and mid-level clouds, and the MODIS satellite provides accurate retrieval of high-level clouds over this region. The CBH algorithm used for the MODIS satellite is also able to capture the low-level clouds.

  18. QUANTITATIVE MODELING OF SUSPENDED SEDIMENT IN MIDDLE CHANGJIANG RIVER FROM MODIS

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Remote sensing techniques have been widely used to observe bodies of water. Among satellite sensors commonly used for water quality studies, the Moderate-resolution Imaging Spectroradiometer (MODIS) has potential in water quality monitoring, because of its moderate spatial resolution and high temporal resolution. In this paper, the utility of MODIS data for suspended sediment monitoring in the middle Changjiang (Yangtze) River is studied. It is concluded that suspended sediment concentration correlates well with reflectance values (R1-R2)/(Ri+R2) retrieved from MODIS 250m image data (R2=0.72, n=41). Based on this correlation, we obtain the empirical model of suspended sediment concentration in the middle Changjiang River from MODIS. It is shown that it is useful for MODIS data to monitor this parameter of water quality.

  19. Moderate resolution imaging spectroradiometer (MODIS) and observations of the land surface

    Science.gov (United States)

    Salomonson, V. V.; Toll, D. L.; Lawrence, W. T.

    1992-01-01

    The moderate resolution imaging spectroradiometer (MODIS) is a NASA facility instrument that is being designed for flight on the Earth Observing System (EOS) series of missions. It is designed to measure biophysical states and dynamics of the land, atmosphere, and ocean. Plans are required for use of other instruments that will be accompanying MODIS on the EOS missions, such as the High-Resolution Imaging Spectrometer (HIRIS) and the Multi-angle Imaging Spectro-Radiometer (MISR). The HIRIS instrument, a spectrometer operating in the visible to shortwave infrared parts of the spectrum, would be employed in combination with the MODIS to understand the impact of sampling the spectrum and the effects of land cover mixtures within the MODIS pixel. The MISR will help in understanding the effects of anisotropy in reflected solar radiation. Both instruments will work in combination with MODIS to better quantify the effects of the atmosphere on observations of surface properties.

  20. MODIS 3 km aerosol product: applications over land in an urban/suburban region

    Directory of Open Access Journals (Sweden)

    L. A. Munchak

    2013-07-01

    Full Text Available MODerate resolution Imaging Spectroradiometer (MODIS instruments aboard the Terra and Aqua satellites have provided a rich dataset of aerosol information at a 10 km spatial scale. Although originally intended for climate applications, the air quality community quickly became interested in using the MODIS aerosol data. However, 10 km resolution is not sufficient to resolve local scale aerosol features. With this in mind, MODIS Collection 6 includes a global aerosol product with a 3 km resolution. Here, we evaluate the 3 km product over the Baltimore–Washington D.C., USA, corridor during the summer of 2011 by comparing with spatially dense aerosol data measured by airborne High Spectral Resolution Lidar (HSRL and a network of 44 sun photometers (SP spaced approximately 10 km apart, collected as part of the DISCOVER-AQ field campaign. The HSRL instrument shows that AOD can vary by over 0.2 within a single 10 km MODIS pixel, meaning that higher resolution satellite retrievals may help to better characterize aerosol spatial distributions in this region. Different techniques for validating a high-resolution aerosol product against SP measurements are considered. Although the 10 km product is more statistically reliable than the 3 km product, the 3 km product still performs acceptably with nearly two-thirds of MODIS/SP collocations falling within an expected error envelope with high correlation (R > 0.90, although with a high bias of ~ 0.06. The 3 km product can better resolve aerosol gradients and retrieve closer to clouds and shorelines than the 10 km product, but tends to show more noise, especially in urban areas. This urban degradation is quantified using ancillary land cover data. Overall, we show that the MODIS 3 km product adds new information to the existing set of satellite derived aerosol products and validates well over the region, but due to noise and problems in urban areas, should be treated with some degree of caution.

  1. MODIS 3 km aerosol product: applications over land in an urban/suburban region

    Directory of Open Access Journals (Sweden)

    L. A. Munchak

    2013-02-01

    Full Text Available MODerate resolution Imaging Spectroradiometer (MODIS instruments aboard the Terra and Aqua satellites have provided a rich dataset of aerosol information at a 10 km spatial scale. Although originally intended for climate applications, the air quality community quickly became interested in using the MODIS aerosol data. However, 10 km resolution is not sufficient to resolve local scale aerosol features. With this in mind, MODIS Collection 6 is including a global aerosol product with a 3 km resolution. Here, we evaluate the 3 km product over the Baltimore/Washington D.C., USA, corridor during the summer of 2011, by comparing with spatially dense data collected as part of the DISCOVER-AQ campaign; these data were measured by the NASA Langley Research Center airborne High Spectral Resolution Lidar (HSRL and a network of 44 sun photometers (SP spaced approximately 10 km apart. The HSRL instrument shows that AOD can vary by up to 0.2 within a single 10 km MODIS pixel, meaning that higher resolution satellite retrievals may help to characterize aerosol spatial distributions in this region. Different techniques for validating a high-resolution aerosol product against SP measurements are considered. Although the 10 km product is more statistically reliable than the 3 km product, the 3 km product still performs acceptably, with more than two-thirds of MODIS/SP collocations falling within the expected error envelope with high correlation (R > 0.90. The 3 km product can better resolve aerosol gradients and retrieve closer to clouds and shorelines than the 10 km product, but tends to show more significant noise especially in urban areas. This urban degradation is quantified using ancillary land cover data. Overall, we show that the MODIS 3 km product adds new information to the existing set of satellite derived aerosol products and validates well over the region, but due to noise and problems in urban areas, should be treated with some degree of

  2. MODIS 3 Km Aerosol Product: Applications over Land in an Urban/suburban Region

    Science.gov (United States)

    Munchak, L. A.; Levy, R. C.; Mattoo, S.; Remer, L. A.; Holben, B. N.; Schafer, J. S.; Hostetler, C. A.; Ferrare, R. A.

    2013-01-01

    MODerate resolution Imaging Spectroradiometer (MODIS) instruments aboard the Terra and Aqua satellites have provided a rich dataset of aerosol information at a 10 km spatial scale. Although originally intended for climate applications, the air quality community quickly became interested in using the MODIS aerosol data. However, 10 km resolution is not sufficient to resolve local scale aerosol features. With this in mind, MODIS Collection 6 is including a global aerosol product with a 3 km resolution. Here, we evaluate the 3 km product over the Baltimore/Washington D.C., USA, corridor during the summer of 2011, by comparing with spatially dense data collected as part of the DISCOVER-AQ campaign these data were measured by the NASA Langley Research Center airborne High Spectral Resolution Lidar (HSRL) and a network of 44 sun photometers (SP) spaced approximately 10 km apart. The HSRL instrument shows that AOD can vary by up to 0.2 within a single 10 km MODIS pixel, meaning that higher resolution satellite retrievals may help to characterize aerosol spatial distributions in this region. Different techniques for validating a high-resolution aerosol product against SP measurements are considered. Although the 10 km product is more statistically reliable than the 3 km product, the 3 km product still performs acceptably, with more than two-thirds of MODIS/SP collocations falling within the expected error envelope with high correlation (R > 0.90). The 3 km product can better resolve aerosol gradients and retrieve closer to clouds and shorelines than the 10 km product, but tends to show more significant noise especially in urban areas. This urban degradation is quantified using ancillary land cover data. Overall, we show that the MODIS 3 km product adds new information to the existing set of satellite derived aerosol products and validates well over the region, but due to noise and problems in urban areas, should be treated with some degree of caution.

  3. Exploring New Methods of Displaying Bit-Level Quality and Other Flags for MODIS Data

    Science.gov (United States)

    Khalsa, Siri Jodha Singh; Weaver, Ron

    2003-01-01

    The NASA Distributed Active Archive Center (DAAC) at the National Snow and Ice Data Center (NSIDC) archives and distributes snow and sea ice products derived from the MODerate resolution Imaging Spectroradiometer (MODIS) on board NASA's Terra and Aqua satellites. All MODIS standard products are in the Earth Observing System version of the Hierarchal Data Format (HDF-EOS). The MODIS science team has packed a wealth of information into each HDF-EOS file. In addition to the science data arrays containing the geophysical product, there are often pixel-level Quality Assurance arrays which are important for understanding and interpreting the science data. Currently, researchers are limited in their ability to access and decode information stored as individual bits in many of the MODIS science products. Commercial and public domain utilities give users access, in varying degrees, to the elements inside MODIS HDF-EOS files. However, when attempting to visualize the data, users are confronted with the fact that many of the elements actually represent eight different 1-bit arrays packed into a single byte array. This project addressed the need for researchers to access bit-level information inside MODIS data files. In an previous NASA-funded project (ESDIS Prototype ID 50.0) we developed a visualization tool tailored to polar gridded HDF-EOS data set. This tool,called the Polar researchers to access, geolocate, visualize, and subset data that originate from different sources and have different spatial resolutions but which are placed on a common polar grid. The bit-level visualization function developed under this project was added to PHDIS, resulting in a versatile tool that serves a variety of needs. We call this the EOS Imaging Tool.

  4. AquaCrop模型及其研究进展%Review on the Processes of AquaCrop Model

    Institute of Scientific and Technical Information of China (English)

    王亮; 魏新平

    2014-01-01

    结合国内外有关AquaCrop模型的研究工作,以研究模型的应用领域为基点,对AquaCrop模型运用成果的特点进行归纳.在此基础上,指出了模型在理论合理性和实际适用性等方面存在的问题,并对AquaCrop模型的发展前景进行了展望,以期为我国作物模型的研究提供借鉴.

  5. Growing up MODIS: Towards a mature aerosol climate data record

    Science.gov (United States)

    Levy, Robert C.

    2013-05-01

    . There are two orbiting MODIS sensors (on Terra and Aqua), and like human twins, they have had different life experiences; the result is a slightly different perspective on global aerosol distribution. To assess simple questions like "Is global aerosol increasing or decreasing?" requires detailed analyses into diverse subjects, such as instrument calibration, assumptions for gas correction, and aggregations of spatial sampling. With the recent launch of VIIRS on Suomi-NPP, there is a new addition to the aerosol monitoring "family." While preliminary indications are that it will produce a successful aerosol product, work on its position within the CDR is just beginning. In 1998, in addition to starting a new job, I joined a unique family composed of scientists around the world. I am grateful that the community has been supportive and nurturing. Of course, like in any family, there are many stories to tell. Here, at IRS-2012, I share some of my experiences of working within the collective MODIS aerosol project.

  6. AIRS/Aqua Level 2G Precipitation Estimate V005

    Data.gov (United States)

    National Aeronautics and Space Administration — The Atmospheric Infrared Sounder (AIRS) is a facility instrument aboard the second Earth Observing System (EOS) polar-orbiting platform, EOS Aqua. In combination...

  7. Retrieval of ice cloud properties using an optimal estimation algorithm and MODIS infrared observations: 2. Retrieval evaluation

    Science.gov (United States)

    Wang, Chenxi; Platnick, Steven; Zhang, Zhibo; Meyer, Kerry; Wind, Gala; Yang, Ping

    2016-05-01

    An infrared-based optimal estimation (OE-IR) algorithm for retrieving ice cloud properties is evaluated. Specifically, the implementation of the algorithm with MODerate resolution Imaging Spectroradiometer (MODIS) observations is assessed in comparison with the operational retrieval products from MODIS on the Aqua satellite (MYD06), Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP), and the Imaging Infrared Radiometer (IIR); the latter two instruments fly on the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellite in the Afternoon Constellation (A-Train) with Aqua. The results show that OE-IR cloud optical thickness (τ) and effective radius (reff) retrievals perform best for ice clouds having 0.5 1 km) occurs for τ < 0.5. Analysis of 1 month of the OE-IR retrievals shows large τ and reff uncertainties in storm track regions and the southern oceans where convective clouds are frequently observed, as well as in high-latitude regions where temperature differences between the surface and cloud top are more ambiguous. Generally, comparisons between the OE-IR and the operational products show consistent τ and h retrievals. However, obvious differences between the OE-IR and the MODIS Collection 6 reff are found.

  8. MODIS snow cover mapping accuracy in a small mountain catchment – comparison between open and forest sites

    Directory of Open Access Journals (Sweden)

    G. Blöschl

    2012-07-01

    Full Text Available Numerous global and regional validation studies have examined MODIS snow mapping accuracy by using measurements at climate stations, which are mainly at open sites. MODIS accuracy in alpine and forested regions is, however, still not well understood. The main objective of this study is to evaluate MODIS (MOD10A1 and MYD10A1 snow cover products in a small experimental catchment by using extensive snow course measurements at open and forest sites. The MODIS accuracy is tested in the Jalovecky creek catchment (northern Slovakia in the period 2000–2011. The results show that the combined Terra and Aqua images enable snow mapping at an overall accuracy of 91.5%. The accuracies at forested, open and mixed land uses at the Červenec sites are 92.7%, 98.3% and 81.8%, respectively. The use of a 2-day temporal filter enables a significant reduction in the number of days with cloud coverage and an increase in overall snow mapping accuracy. In total, the 2-day temporal filter decreases the number of cloudy days from 61% to 26% and increases the snow mapping accuracy to 94%. The results indicate three possible factors leading to misclassification of snow as land: patchy snow cover, limited MODIS geolocation accuracy and mapping algorithm errors. Out of a total of 27 misclassification cases, patchy snow cover, geolocation issues and mapping errors occur in 12, 12 and 3 cases, respectively.

  9. Application of MODIS Data on the Drought Monitoring of Hubei Province%MODIS 数据在湖北旱情监测中的应用

    Institute of Scientific and Technical Information of China (English)

    刁伟; 孟令奎; 张东映; 郭善昕

    2013-01-01

      使用Aqua和Terra卫星MODIS传感器获取的遥感影像数据,结合历史库归一化的垂直干旱指数模型,对湖北省2012年8月份旱情进行重点监测和分析,并利用实测数据对监测结果进行应用评价。结果表明基于MODIS数据的归一化垂直干旱指数在湖北省旱情监测中具有良好的应用效果。%The drought of the Hubei province in August 2012 is detected with the MODIS sensor data of the Aqua and Terra satellites, using the normalized PDI with the history images. By comparing with the measured data by hydrologic station, we analysis the achievements of the monitoring results of MODIS data. This paper concludes that the normalized PDI based on MODIS data is applicable and has a potential application in the drought monitoring of Hubei province.

  10. Remote sensing of water vapor in the near IR from EOS/MODIS

    Science.gov (United States)

    Kaufman, Yoram J.; Gao, Bo-Cai

    1992-01-01

    Consideration is given to the selection of spectral channels in the near-infrared IR which are to be employed for the derivation of total column water vapor using the MODIS instrument on the NASA's Earth Observing System. Data obtained show that the three near-IR water vapor channels on the MODIS instrument enable remote sensing of the total column water vapor with an absolute accuracy of +/- 13 percent. An absolute accuracy of +/-7 percent can be obtained if additional MODIS channels are used to decrease the effect of uncertainty in the spectral reflectance of the surface, subpixel clouds, haze, and temperature profile on the derived water vapor.

  11. Estimating Global Cropland Extent with Multi-year MODIS Data

    Directory of Open Access Journals (Sweden)

    Christopher O. Justice

    2010-07-01

    Full Text Available This study examines the suitability of 250 m MODIS (MODerate Resolution Imaging Spectroradiometer data for mapping global cropland extent. A set of 39 multi-year MODIS metrics incorporating four MODIS land bands, NDVI (Normalized Difference Vegetation Index and thermal data was employed to depict cropland phenology over the study period. Sub-pixel training datasets were used to generate a set of global classification tree models using a bagging methodology, resulting in a global per-pixel cropland probability layer. This product was subsequently thresholded to create a discrete cropland/non-cropland indicator map using data from the USDA-FAS (Foreign Agricultural Service Production, Supply and Distribution (PSD database describing per-country acreage of production field crops. Five global land cover products, four of which attempted to map croplands in the context of multiclass land cover classifications, were subsequently used to perform regional evaluations of the global MODIS cropland extent map. The global probability layer was further examined with reference to four principle global food crops: corn, soybeans, wheat and rice. Overall results indicate that the MODIS layer best depicts regions of intensive broadleaf crop production (corn and soybean, both in correspondence with existing maps and in associated high probability matching thresholds. Probability thresholds for wheat-growing regions were lower, while areas of rice production had the lowest associated confidence. Regions absent of agricultural intensification, such as Africa, are poorly characterized regardless of crop type. The results reflect the value of MODIS as a generic global cropland indicator for intensive agriculture production regions, but with little sensitivity in areas of low agricultural intensification. Variability in mapping accuracies between areas dominated by different crop types also points to the desirability of a crop-specific approach rather than attempting

  12. Significant overestimation of global aerosol optical thickness by MODIS over land

    Institute of Scientific and Technical Information of China (English)

    XIA Xiang'ao

    2006-01-01

    Global aerosol optical thickness (AOT)data over land obtained from the Moderate Resolution Imaging Spectroradiometer (MODIS) are evaluated through comparisons with AOT data retrieved by Aerosol Robotic Network (AERONET). In general,MODIS overestimates AOT except at a few AERONET sites in Africa and eastern Asia. MODIS/AOTs are, on average, larger than AERONET/AOTs by 0.041 and 0.090 at 470 nm and 660 nm, respectively. The AOT bias at 660 nm is significantly correlated to the surface reflectance at 2130 nm. Both facts suggest that the underestimation of the surface reflectance is the principal reason for this bias at 660 nm. To use the MODIS/AOT at 470 nm is strongly recommended because it is much more reliable than the AOT at 660 nm.

  13. Comparison of MISR and MODIS land surface albedos: Methodology

    Science.gov (United States)

    Taberner, M.; Pinty, B.; Govaerts, Y.; Liang, S.; Verstraete, M. M.; Gobron, N.; Widlowski, J.-L.

    2010-03-01

    The broadband white sky surface albedo (bihemispherical reflectance) products available from the Moderate Resolution Imaging Spectroradiometer (MODIS) are compared at regional and continental scales with similar products generated from the Multiangle Imaging Spectroradiometer (MISR) land surface bidirectional reflectance factor (BRF) parameters. This paper describes the methodology applied to derive MISR white sky albedos over four spectral broadbands of interest, namely, 0.3-0.7 μm, 0.4-1.1 μm, 0.7-3.0 μm, and 0.3-3.0 μm, as well as an evaluation of the strategy adopted to compare the MODIS and MISR products. The results are very encouraging since the two data sets show very good statistical agreement over large areas and over a full year of measurements, despite the many differences that exist in the suite of algorithms applied to retrieve these surface quantities from each of these instruments separately.

  14. Mapping Snow Grain Size over Greenland from MODIS

    Science.gov (United States)

    Lyapustin, Alexei; Tedesco, Marco; Wang, Yujie; Kokhanovsky, Alexander

    2008-01-01

    This paper presents a new automatic algorithm to derive optical snow grain size (SGS) at 1 km resolution using Moderate Resolution Imaging Spectroradiometer (MODIS) measurements. Differently from previous approaches, snow grains are not assumed to be spherical but a fractal approach is used to account for their irregular shape. The retrieval is conceptually based on an analytical asymptotic radiative transfer model which predicts spectral bidirectional snow reflectance as a function of the grain size and ice absorption. The analytical form of solution leads to an explicit and fast retrieval algorithm. The time series analysis of derived SGS shows a good sensitivity to snow metamorphism, including melting and snow precipitation events. Preprocessing is performed by a Multi-Angle Implementation of Atmospheric Correction (MAIAC) algorithm, which includes gridding MODIS data to 1 km resolution, water vapor retrieval, cloud masking and an atmospheric correction. MAIAC cloud mask (CM) is a new algorithm based on a time series of gridded MODIS measurements and an image-based rather than pixel-based processing. Extensive processing of MODIS TERRA data over Greenland shows a robust performance of CM algorithm in discrimination of clouds over bright snow and ice. As part of the validation analysis, SGS derived from MODIS over selected sites in 2004 was compared to the microwave brightness temperature measurements of SSM\\I radiometer, which is sensitive to the amount of liquid water in the snowpack. The comparison showed a good qualitative agreement, with both datasets detecting two main periods of snowmelt. Additionally, MODIS SGS was compared with predictions of the snow model CROCUS driven by measurements of the automatic whether stations of the Greenland Climate Network. We found that CROCUS grain size is on average a factor of two larger than MODIS-derived SGS. Overall, the agreement between CROCUS and MODIS results was satisfactory, in particular before and during the

  15. Methodology to obtain 30 m resolution of snow cover area from FSCA MODIS and NDSI Landsat

    Science.gov (United States)

    Cepeda, Javier; Vargas, Ximena

    2016-04-01

    In the last years numerous free images and product satellites have been released, with different spatial and temporal resolution. Out of them, the most commonly used to describe the snow area are MODIS and Landsat. Fractional snow cover area (FSCA) is a daily MODIS product with a 500 m spatial resolution; Landsat images have around 16 days and 30 m respectively. In this work we use both images to obtain a new daily 30 m resolution snow distribution product based in probabilistic and geospatial information. This can be useful because a higher resolution can be used to improve the estimation of the accuracy of a physically-based distributed model to represent the snow cover distribution. We choose three basins in central Chile, with an important snow and glacier presence, to analyze the spatial and temporal distribution of snow using (1) the mean value between MOD10A1 (terra) and MYD10A1 (aqua) and (2) the corrected images by topography and atmosphere from Landsat 5 and Landsat 8 computing the normalized difference snow index (NDSI). When both satellites data are available in the same day, each MODIS pixel is studied considering the Landsat pixels contained in it. A new matrix is created, covering all MODIS pixels, using a 30 m spatial resolution, where each pixel value represents the probability of snow presence in time from Landsat images, and then each pixel is corrected by its neighbour's pixels, elevation, slope and aspect. Then snow is distributed, for each MODIS pixel, considering the corrected probability matrix and sorted between pixels with high probability until the area from FSCA is completed.

  16. MODIS 3 km aerosol product: algorithm and global perspective

    OpenAIRE

    Remer, L. A.; Mattoo, S; R. C. Levy; L. A. Munchak

    2013-01-01

    After more than a decade of producing a nominal 10 km aerosol product based on the dark target method, the MODerate resolution Imaging Spectroradiometer (MODIS) aerosol team will be releasing a nominal 3 km product as part of their Collection 6 release. The new product differs from the original 10 km product only in the manner in which reflectance pixels are ingested, organized and selected by the aerosol algorithm. Overall, the 3 km product closely mirrors the 10 km product. H...

  17. Aerosol radiative effects over global arid and semi-arid regions based on MODIS Deep Blue satellite observations

    Science.gov (United States)

    Hatzianastassiou, Nikolaos; Papadimas, Christos D.; Gkikas, Antonis; Matsoukas, Christos; Sayer, Andrew M.; Hsu, N. Christina; Vardavas, Ilias

    2014-05-01

    Aerosols are a key parameter for several atmospheric processes related to weather and climate of our planet. Specifically, the aerosol impact on Earth's climate is exerted and quantified through their radiative effects, which are induced by their direct, indirect and semi-direct interactions with radiation, in particular at short wavelengths (solar). It is acknowledged that the uncertainty of present and future climate assessments is mainly associated with aerosols and that a better understanding of their physico-chemical, optical and radiative effects is needed. The contribution of satellites to this aim is important as a complementary tool to climate and radiative transfer models, as well as to surface measurements, since space observations of aerosol properties offer an extended spatial coverage. However, such satellite based aerosol properties and associated model radiation computations have suffered from unavailability over highly reflecting surfaces, namely polar and desert areas. This is also the case for MODIS which, onboard the Terra and Aqua satellites, has been providing high quality aerosol data since 2000 and 2002, respectively. These data, more specifically the aerosol optical depth (AOD) which is the most important optical property used in radiative and climate models, are considered to be of best quality. In order to address this problem, the MODIS Deep Blue (DB) algorithm has been developed which enables the retrieval of AOD above arid and semi-arid areas of the globe, including the major deserts. In the present study we make use of the FORTH detailed spectral radiative transfer model (RTM) with MODIS DB AOD data, supplemented with single scattering albedo (SSA) and asymmetry parameter (AP) aerosol data from the Global Aerosol DataSet (GADS) to estimate the aerosol DREs over the arid and semi-arid regions of the globe. The RTM is run using surface and atmospheric data from the ISCCP-D2 dataset and the NCEP global reanalysis project and computes the

  18. Improvement of MODIS RSB calibration by minimizing the Earthshine impact on solar diffuser observations

    Science.gov (United States)

    Xie, X.; Xiong, X.; Wolfe, R.; Lyapustin, A.

    2006-08-01

    The MODerate Resolution Imaging Spectroraiometer (MODIS) reflective solar bands (RSB) are calibrated on-orbit using solar illuminations reflected from its onboard solar diffuser (SD) plate. The specified calibration uncertainty requirements for MODIS RSB are +/-2% in reflectance and +/-5% in radiance at their typical top of atmosphere (TOA) radiances. The onboard SD bi-directional reflectance factor (BRF) was characterized pre-launch by the instrument vendor using reference samples traceable to NIST reflectance standard. The SD on-orbit degradation is monitored using a solar diffuser stability monitor (SDSM). One of contributors to the RSB calibration uncertainty is the earthshine (ES) illumination on the SD plate during SD calibration. This effect was estimated pre-launch by the instrument vendor to be of 0.5% for all RSB bands. Analyses of on-orbit observations show that some of the SD calibration data sets have indeed been contaminated due to extra ES illumination and the degree of ES impact on the SD calibration is spectrally dependent and varies with geo-location and atmospheric conditions (ground surface type and cloudiness). This paper illustrates the observed ES impacts on the MODIS RSB calibration quality and compare them with the effects derived from an ES model based on the viewing geometry of MODIS SD aperture door and likelihood atmospheric conditions. It also describes an approach developed to minimize the ES impact on MODIS RSB calibration.

  19. Comparison and Analysis of MODIS NDVI and MODIS EVI%MODIS NDVI与MODIS EVI的比较分析

    Institute of Scientific and Technical Information of China (English)

    李文梅; 覃志豪; 李文娟; 杨强

    2010-01-01

    MODIS NDVI与MODIS EVI是目前应用比较广泛的植被指数,MODIS EVI是对NDVI的发展和延续,从植被指数计算公式和合成方法两方面做了改进.具体表现在:避免了MODIS NDVI在植被高覆盖区易饱和的问题,考虑了土壤背景对植被指数的影响,对气溶胶等残留做了进一步校正,采用BRDF/CV-MVC合成方法保证了合成采用最佳像元.EVI时间序列相较于NDVI时间序列季节性更明显,能够更好地反映高植被覆盖区的季节性变化特征,并且很少有突降现象,时间序列曲线较平滑.EVI的这些优势为高覆盖植被物候特征的季节性变化监测提供了新的思路.

  20. MODIS Hotspot Validation over Thailand

    Directory of Open Access Journals (Sweden)

    Veerachai Tanpipat

    2009-11-01

    Full Text Available To ensure remote sensing MODIS hotspot (also known as active fire products or hotspots quality and precision in forest fire control and management in Thailand, an increased level of confidence is needed. Accuracy assessment of MODIS hotspots utilizing field survey data validation is described. A quantitative evaluation of MODIS hotspot products has been carried out since the 2007 forest fire season. The carefully chosen hotspots were scattered throughout the country and within the protected areas of the National Parks and Wildlife Sanctuaries. Three areas were selected as test sites for validation guidelines. Both ground and aerial field surveys were also conducted in this study by the Forest Fire Control Division, National Park, Wildlife and Plant Conversation Department, Ministry of Natural Resources and Environment, Thailand. High accuracy of 91.84 %, 95.60% and 97.53% for the 2007, 2008 and 2009 fire seasons were observed, resulting in increased confidence in the use of MODIS hotspots for forest fire control and management in Thailand.

  1. Analysing MODIS Phenometrics Quality on Cropped Land in West Africa

    Science.gov (United States)

    Vintrou, Elodie; Begue, Agnes; Baron, Christian; Lo Seen, Danny; Alexandre, Saad; Traore, Seydou

    2012-04-01

    Crop phenology is essential information when evaluating crop production in the food insecure regions of West Africa. The only currently available global product that includes phenological variables is the MODIS Land Cover Dynamics Yearly (MCD12Q2) product. This product is produced each year at 500 m spatial resolution, from the 8-day vegetation index EVI (Enhanced Vegetation Index) calculated from the NBAR reflectance (Nadir Bidirectional Reflectance Distribution Function - Adjusted Reflectance). In order to analyze the information content of MODIS MCD12Q2 product, the phenological variables were extracted for areas previously identified as cropped on eight specific sites in Mali and compared to rainfall data and expert knowledge on Malian agriculture. MODIS MCD12Q2 data analysis showed that only 70% of the cropped pixels in Southern Mali had a complete phenology information on the whole vegetation cycle (four phenometrics values), and that a large part of the pixels displayed unrealistic late Start-Of-Season (SOS) values. A close analysis of the original EVI data indicated that these inconsistent SOS values were due to missing EVI data during the vegetation development phase (due to the presence of cloud cover) conducting to a false detection of SOS. We then proposed a simple way to correct the SOS values. In Africa, food security systems could benefit from such a phenology product, by utilizing its spatially continuous information in agro-meteorological modeling, and thus improving agricultural production estimation.

  2. Cloud and Aerosol Properties, Precipitable Water, and Profiles of Temperature and Water Vapor from MODIS

    Science.gov (United States)

    King, Michael D.; Menzel, W. Paul; Kaufman, Yoram J.; Tanre, Didier; Gao, Bo-Cai; Platnick, Steven; Ackerman, Steven A.; Remer, Lorraine A.; Pincus, Robert; Hubanks, Paul A.

    2003-01-01

    The Moderate Resolution Imaging Spectroradiometer (MODIS) is an earth-viewing sensor that flies on the Earth Observing System (EOS) Terra and Aqua satellites, launched in 1999 and 2002, respectively. MODIS scans a swath width of 2330 km that is sufficiently wide to provide nearly complete global coverage every two days from a polar-orbiting, sun-synchronous, platform at an altitude of 705 km. MODIS provides images in 36 spectral bands between 0.415 and 14.235 pm with spatial resolutions of 250 m (2 bands), 500 m (5 bands) and 1000 m (29 bands). These bands have been carefully selected to en- able advanced studies of land, ocean, and atmospheric properties. Twenty-six bands are used to derive atmospheric properties such as cloud mask, atmospheric profiles, aerosol properties, total precipitable water, and cloud properties. In this paper we describe each of these atmospheric data products, including characteristics of each of these products such as file size, spatial resolution used in producing the product, and data availability.

  3. Evaluation of cloud base height measurements from ceilometer CL31 and MODIS satellite over Ahmedabad, India

    Directory of Open Access Journals (Sweden)

    S. Sharma

    2015-11-01

    Full Text Available Clouds play a tangible role in the Earth's atmosphere and in particular, the cloud base height (CBH which is linked to cloud type is one of the important characteristic to describe the influence of clouds on the environment. In present study, CBH observations from ceilometer CL31 have been extensively studied during May 2013 to January 2015 over Ahmedabad (23.03° N, 72.54° E, India. A detail comparison has been performed with the use of ground-based CBH measurements from ceilometer CL31 and CBH retrieved from MODIS (Moderate Resolution Imaging Spectroradiometer onboard Aqua and Terra satellite. Some interesting features of cloud dynamics viz. strong downdraft and updraft have been observed over Ahmedabad which revealed different cloud characteristics during monsoon and post-monsoon periods. CBH shows seasonal variation during Indian summer monsoon and post-monsoon period. Results indicate that ceilometer is one of the excellent instruments to precisely detect low and mid-level clouds and MODIS satellite provides accurate retrieval of high-level clouds over this region. The CBH algorithm used for MODIS satellite is also able to capture the low-level clouds.

  4. Detection of dust and sandstorms from Taklamakan Desert to Japan by using MODIS mosaic images

    Science.gov (United States)

    Kato, Yoshinobu

    2008-12-01

    In recent years, the number of days which dust and sandstorms (DSS) events were observed is increasing in Japan, Korea, China and Mongolia. The Aerosol Vapor Index (AVI) method is a DSS detection method. The AVI is defined as AVI=Tb32-Tb31 for MODIS data of Terra and Aqua satellites, where Tb31 is the brightness temperature of band 31 (10.780-11.280μm) and Tb32 is that of band 32 (11.770-12.270μm). The MODIS mosaic images of true-color, AVI and thermal images are made for the detection of DSS from Taklamakan Desert to Japan. The detection of DSS is possible both at daytime and night, because the AVI method is used. The density of DSS is classified into six levels from 0 (DSS none) to 5 (DSS strong) according to the AVI values. The DSS phenomena during 6-11 April 2006 are analyzed by using the mosaic images of Terra-MODIS. The number of pixels, which is approximately equal to the area of square kilometers, at each level of DSS density is measured. The AVI value at sea is about 0.2-2.3K lower than that at land, because of the influence of water vapor. In daytime, the generation place of DSS hidden under the cloud can be estimated by comparing AVI image with true-color and thermal images.

  5. An improved MODIS standard chlorophyll-a algorithm for Malacca Straits Water

    International Nuclear Information System (INIS)

    The Malacca Straits has high productivity of nutrients as a result to potential primary production. Yet, the Moderate Resolution Imaging Spectroradiometer (MODIS) Aqua has shown an overestimation of Chl-a retrieval in the case-2 water of Malacca Straits. In an update to the previous study, this paper presents the second validation exercise of MODIS OC3M algorithm using the reprocessed MODIS data (R2013) and locally tuned the algorithm with respect to two in-sit stations located at northern and southern part of Malacca Straits. The result shows the OC3M retrieved in the case-2 (south station) water remarkably overestimated in-situ Chl-a, but it is underestimated in the case-1 (north station). Local tuning was employed by iterative regression at the fourth-order polynomial to improve the accuracy of Chl-a retrieval. As a result, locally tuned OC3M algorithm give robust statistical performance and can be applied best for both case-1 and case-2 water in Malacca Straits

  6. Estimation of chlorophyll-a using MERSI and MODIS images in Taihu Lake, China%基于MERSI和MODIS的太湖水体叶绿素a含量反演

    Institute of Scientific and Technical Information of China (English)

    韩秀珍; 郑伟; 刘诚; 安思颖

    2011-01-01

    The Chlorophyll-a (Chl-a) concentrations in water are of great importance to the monitoring of water quality and ecosystem balance. Remote sensing offers a convenient and systematical tool for the observations of water at a long time scale. In this paper, we present a study of Chl-a estimation using the reflectance models (MOD3: R(-1)(λ1)-R(-1)(λ2)) ×Rλ3 and MOD2 :R(-1)(λ1) ×Rλ3) derived from the Medium Resolution Spectral Image (MERSI) on board the newly launched FY-3A satellite and the Moderate Imaging Spectroradiometer (MODIS) onboard the AQUA platforms. Validation studies demonstrated that both models provided reliable estimates of Chl-a concentrations with determination coefficients R2 of 0.72~0.79 (MOD2) and 0. 52~0.76 (MOD3) for MERSI standard band settings. This accuracy is slightly better than that of the MODIS results with R2 of 0. 65~0.69 and 0.43 ~0. 70 for MOD2 and MOD3, respectively. Comparison analysis between models and sensors indicated that the blue and near infrared wave ranges are of potential for Chl-a estimation. Besides, the higher spatial resolution of MERSI (250m) may explain the better performance for both models compared to that of MODIS. This research will be helpful for the development of future Chl-a estimation models using the satellite observations.%水体叶绿素a含量的遥感反演是监测水体光学特性、评价水体污染的一个重要指标.本文以FY-3A/MERSI和AQUA/MODIS遥感影像为数据源,结合水体实测的叶绿索a含量,利用两类反射率模型,研究星载数据遥感反演叶绿素a的可行性.研究表明:基于FY-3A/MERSI和AQUA/MODIS可见光-近红外通道的光谱反演模型(R-1λ1-R-1λ2)×Rλ3和R-1λ1×Rλ3在太湖水体叶绿素a含量反演方面取得了较高的精度.基于MERISI通道的模型反演相关系数R2分别在0.60和0.72左右,基于MODIS通道的模型反演相关系数R2分别在0.55和0.65左右.通过比较分析,决定叶绿素a含量反演精度的

  7. On the influence of the diurnal variations of aerosol content to estimate direct aerosol radiative forcing using MODIS data

    Science.gov (United States)

    Xu, Hui; Guo, Jianping; Ceamanos, Xavier; Roujean, Jean-Louis; Min, Min; Carrer, Dominique

    2016-09-01

    Long-term measurements of aerosol optical depth (AOD) from the Aerosol Robotic Network (AERONET) located in Beijing reveal a strong diurnal cycle of aerosol load staged by seasonal patterns. Such pronounced variability is matter of importance in respect to the estimation of daily averaged direct aerosol radiative forcing (DARF). Polar-orbiting satellites could only offer a daily revisit, which turns in fact to be even much less in case of frequent cloudiness. Indeed, this places a severe limit to properly capture the diurnal variations of AOD and thus estimate daily DARF. Bearing this in mind, the objective of the present study is however to evaluate the impact of AOD diurnal variations for conducting quantitative assessment of DARF using Moderate Resolution Imaging Spectroradiometer (MODIS) AOD data over Beijing. We provide assessments of DARF with two different assumptions about diurnal AOD variability: taking the observed hourly-averaged AOD cycle into account and assuming constant MODIS (including Terra and Aqua) AOD value throughout the daytime. Due to the AOD diurnal variability, the absolute differences in annual daily mean DARFs, if the constant MODIS/Terra (MODIS/Aqua) AOD value is used instead of accounting for the observed hourly-averaged daily variability, is 1.2 (1.3) Wm-2 at the top of the atmosphere, 27.5 (30.6) Wm-2 at the surface, and 26.4 (29.3) Wm-2 in the atmosphere, respectively. During the summertime, the impact of the diurnal AOD variability on seasonal daily mean DARF estimates using MODIS Terra (Aqua) data can reach up to 2.2 (3.9) Wm-2 at the top of the atmosphere, 43.7 (72.7) Wm-2 at the surface, and 41.4 (68.8) Wm-2 in the atmosphere, respectively. Overall, the diurnal variation in AOD tends to cause large bias in the estimated DARF on both seasonal and annual scales. In summertime, the higher the surface albedo, the stronger impact on DARF at the top of the atmosphere caused by dust and biomass burning (continental) aerosol. This

  8. Systematic errors in temperature estimates from MODIS data covering the western Palearctic and their impact on a parasite development model.

    Science.gov (United States)

    Alonso-Carné, Jorge; García-Martín, Alberto; Estrada-Peña, Agustin

    2013-11-01

    The modelling of habitat suitability for parasites is a growing area of research due to its association with climate change and ensuing shifts in the distribution of infectious diseases. Such models depend on remote sensing data and require accurate, high-resolution temperature measurements. The temperature is critical for accurate estimation of development rates and potential habitat ranges for a given parasite. The MODIS sensors aboard the Aqua and Terra satellites provide high-resolution temperature data for remote sensing applications. This paper describes comparative analysis of MODIS-derived temperatures relative to ground records of surface temperature in the western Palaearctic. The results show that MODIS overestimated maximum temperature values and underestimated minimum temperatures by up to 5-6 °C. The combined use of both Aqua and Terra datasets provided the most accurate temperature estimates around latitude 35-44° N, with an overestimation during spring-summer months and an underestimation in autumn-winter. Errors in temperature estimation were associated with specific ecological regions within the target area as well as technical limitations in the temporal and orbital coverage of the satellites (e.g. sensor limitations and satellite transit times). We estimated error propagation of temperature uncertainties in parasite habitat suitability models by comparing outcomes of published models. Error estimates reached 36% of annual respective measurements depending on the model used. Our analysis demonstrates the importance of adequate image processing and points out the limitations of MODIS temperature data as inputs into predictive models concerning parasite lifecycles. PMID:24258878

  9. Air Temperature Estimation over the Third Pole Using MODIS LST

    Science.gov (United States)

    Zhang, H.; Zhang, F.; Ye, M.; Che, T.

    2015-12-01

    The Third Pole is centered on the Tibetan Plateau (TP), which is the highest large plateau around the world with extremely complex terrain and climate conditions, resulting in very scarce meteorological stations especially in the vast west region. For these unobserved areas, the remotely sensed land surface temperature (LST) can greatly contribute to air temperature estimation. In our research we utilized the MODIS LST production from both TERRA and AQUA to estimate daily mean air temperature over the TP using multiple statistical models. Other variables used in the models include longitudes, latitudes, Julian day, solar zenith, NDVI and elevation. To select a relatively optimal model, we chose six popular and representative statistical models as candidate models including the multiple linear regression (MLR), the partial least squares regression (PLS), back propagate neural network (BPNN), support vector regression (SVR), random forests (RF) and Cubist regression (CR). The performances of the six models were compared for each possible combination of LSTs at four satellite pass times and two quality situations. Eventually a ranking table consisting of optimal models for each LST combination and quality situation was built up based on the validation results. By this means, the final production is generated providing daily mean air temperature with the least cloud blockage and acceptable accuracy. The average RMSEs of cross validation are mostly around 2℃. Stratified validations were also performed to test the expansibility to unobserved and high-altitude areas of the final models selected.

  10. EOS Aqua: Mission Status at Earth Science Constellation

    Science.gov (United States)

    Guit, Bill

    2016-01-01

    This is an EOS Aqua Mission Status presentation to be given at the MOWG meeting in Albuquerque NM. The topics to discus are: mission summary, spacecraft subsystems summary, recent and planned activities, inclination adjust maneuvers, propellant usage and lifetime estimate, and mission summary.

  11. Assessment of MODIS sun-sensor geometry variations effect on observed NDVI using MSG SEVIRI geostationary data

    DEFF Research Database (Denmark)

    Fensholt, R.; Sandholt, I.; Proud, Simon Richard;

    2010-01-01

    viewing geometry on red, near-infrared (NIR) and NDVI needs to be quantified. Data from the geostationary MSG (Meteosat Second Generation) SEVIRI (Spinning Enhanced Visible and Infrared Imager) sensor is well suited for this purpose due to the fixed position of the sensor, the spectral resolution...... cloud cover for three consecutive years (2004-2006). An analysis covering the entire range of NDVI revealed day-to-day variations in observed MODIS NDVI of 50-60% for medium dense vegetation (NDVI approximate to 0.5) caused by variations in MODIS view zenith angles (VZAs) between nadir and the high...... forward-scatter view direction. Statistical analysis on red, NIR and NDVI from MODIS and MSG SEVIRI for three transects (characterized by different vegetation densities) showed that both MODIS red and NIR reflectances are highly dependant on MODIS VZA and relative azimuth angle (RAA), due...

  12. Depolarization ratio and attenuated backscatter for nine cloud types: analyses based on collocated CALIPSO lidar and MODIS measurements.

    Science.gov (United States)

    Cho, Hyoun-Myoung; Yang, Ping; Kattawar, George W; Nasiri, Shaima L; Hu, Yongxiang; Minnis, Patrick; Trepte, Charles; Winker, David

    2008-03-17

    This paper reports on the relationship between lidar backscatter and the corresponding depolarization ratio for nine types of cloud systems. The data used in this study are the lidar returns measured by the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) aboard the Cloud- Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite and the collocated cloud products derived from the observations made by the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard Aqua satellite. Specifically, the operational MODIS cloud optical thickness and cloud-top pressure products are used to classify cloud types on the basis of the International Satellite Cloud Climatology Project (ISCCP) cloud classification scheme. While the CALIPSO observations provide information for up to 10 cloud layers, in the present study only the uppermost clouds are considered. The layer-averaged attenuated backscatter (gamma') and layer-averaged depolarization ratio (delta) from the CALIPSO measurements show both water- and ice-phase features for global cirrus, cirrostratus, and deep convective cloud classes. Furthermore, we screen both the MODIS and CALIPSO data to eliminate cases in which CALIPSO detected two- or multi-layered clouds. It is shown that low gamma' values corresponding to uppermost thin clouds are largely eliminated in the CALIPSO delta-gamma' relationship for single-layered clouds. For mid-latitude and polar regions corresponding, respectively, to latitude belts 30 degrees -60 degrees and 60 degrees -90 degrees in both the hemispheres, a mixture of water and ice is also observed in the case of the altostratus class. MODIS cloud phase flags are also used to screen ice clouds. The resultant water clouds flagged by the MODIS algorithm show only water phase feature in the delta-gamma' relation observed by CALIOP; however, in the case of the ice clouds flagged by the MODIS algorithm, the co-existence of ice- and water-phase clouds is still observed in

  13. Evaluation of MODIS vegetation indices for detecting deforestation in Amazonia

    Directory of Open Access Journals (Sweden)

    Yosio Edemir Shimabukuro

    2007-06-01

    Full Text Available Vegetation indices (NDVI and EVI obtained from MODIS products (250 m and 500m, surface reflectance were evaluated in relation to the possibility of detecting and monitoring deforestation areas in Amazonia. A new vegetation index, the DNRG (Normalized Difference between Red and Green spectral bands, was proposed with the same objective. The radiometric quality of the multi-date MODIS products was evaluated to verify the possibility of using vegetation index to generate deforestation maps. The internal accuracy of multi-date composites were evaluated providing a value of positional error less than 1 pixel (< 250 m and, consequently geometric corrections were not necessary. The potential of surface reflectance MODIS products was evaluated in the region of Terra do Meio (Pará State, Brazil, between latitudes 06?00’S to 08?00’S and longitudes 51?00’W to 54?00’W, using the Euclidian minimum distance supervised algorithm of classification. Global accuracies above 87% were obtained demonstrating a good potential for using these products in systems for deforestation detection in near real time.

  14. MODIS Level-3 Standard Mapped Image

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA CoastWatch distributes chlorophyll-a concentration data from NASA's Aqua Spacecraft. Measurements are gathered by the Moderate Resolution Imaging...

  15. Pre-Launch Algorithm and Data Format for the Level 1 Calibration Products for the EOS AM-1 Moderate Resolution Imaging Spectroradiometer (MODIS)

    Science.gov (United States)

    Guenther, Bruce W.; Godden, Gerald D.; Xiong, Xiao-Xiong; Knight, Edward J.; Qiu, Shi-Yue; Montgomery, Harry; Hopkins, M. M.; Khayat, Mohammad G.; Hao, Zhi-Dong; Smith, David E. (Technical Monitor)

    2000-01-01

    The Moderate Resolution Imaging Spectroradiometer (MODIS) radiometric calibration product is described for the thermal emissive and the reflective solar bands. Specific sensor design characteristics are identified to assist in understanding how the calibration algorithm software product is designed. The reflected solar band software products of radiance and reflectance factor both are described. The product file format is summarized and the MODIS Characterization Support Team (MCST) Homepage location for the current file format is provided.

  16. New Global Deep Blue Aerosol Product over Land and Ocean from VIIRS, and Its comparisons with MODIS

    Science.gov (United States)

    Hsu, N. Y. C.; Bettenhausen, C.; Sayer, A. M.; Lee, J.; Tsay, S. C.; Carletta, N.

    2015-12-01

    The impacts of natural and anthropogenic sources of air pollution on climate and human health have continued to gain attention from the scientific community. In order to facilitate these effects, high quality consistent long-term global aerosol data records from satellites are essential. Several EOS-era instruments (e.g., SeaWiFS, MODIS, and MISR) are able to provide such information with a high degree of fidelity. However, with the aging MODIS sensors and the launch of the VIIRS instrument on Suomi NPP in late 2011, the continuation of long-term aerosol data records suitable for climate studies from MODIS to VIIRS is needed urgently. VIIRS was designed to have similar capabilities to MODIS, with similar visible/infrared spectral channels, and spatial/ temporal resolution. However, small but significant differences in several key channels used in aerosol retrievals between MODIS and VIIRS mean that significant effort is required to revise aerosol models and surface reflectance determination modules previously developed using MODIS data. In this study, we will show the global (land and ocean) distribution of aerosols from Version 1 of the VIIRS Deep Blue data set. The preliminary validation results of these new VIIRS Deep Blue aerosol products using data from AERONET sunphotometers over land and ocean will be discussed. We will also compare the monthly averaged Deep Blue aerosol optical thickness (AOT) from VIIRS with the MODIS C6 products to investigate if any systematic biases may exist between MODIS C6 and VIIRS AOT.

  17. Moderate Resolution Imaging Spectroradiometer (MODIS) - Terra

    Data.gov (United States)

    National Aeronautics and Space Administration — This dataset represents multiple products archived at the multiple archive centers for the MODIS (Moderate Resolution Imaging Spectroradiometer) instrument aboard...

  18. The effect of land cover heterogeneity of MODIS pixel on canopy LAI estimation

    Science.gov (United States)

    Manninen, T.; Puttonen, N.

    2012-04-01

    The boreal zone land cover has a very significant influence on the northern hemisphere albedo and is an important component of the northern hemisphere carbon budget. Both albedo and the leaf area index (LAI) are one of the most important biophysical vegetation parameters and belong to the Essential Climate Variables (ECV) . In addition, in winter time the boreal forest albedo is a complicated combination of snow and canopy radiative properties, so that the albedo is a function of the canopy LAI. One possibility to estimate LAI using optical satellite data is by determination of spectral vegetation indices (SVIs), such as the reduced simple ratio (RSR). It uses the visible near infrared and short wave infrared channels. In large areas moderate resolution instruments, like MODIS, are suitable for LAI mapping. Yet, the heterogeneity of land cover in many boreal areas, for example in Finland, causes a challenge for LAI estimation. This effect was studied using several Landsat and MODIS images and the high resolution CORINE land cover map covering the same area in various parts of Finland. The atmospheric correction of the Landsat images was adjusted so that each MODIS pixel reflectance matched the average of the Landsat pixel reflectances within the MODIS pixel. The LAI values for Landsat and MODIS images were then determined using the RSR index. The LAI average of forested Landsat pixels was compared to the corresponding MODIS pixel LAI as a function of open water area fraction in the MODIS pixel. A regression function was determined to derive a method to correct the MODIS based LAI values with the open water area fraction. It turned out that the existence of open water in the MODIS pixels reduces the determined canopy LAI value on the average 30%. Also other land cover classes affect the LAI value, but the effect of water is largest, because the reflectance of water deviates so much from that of the canopy. The canopy LAI map of whole Finland was then calculated

  19. Orbiting Carbon Observatory-2 (OCO-2) cloud screening algorithms: validation against collocated MODIS and CALIOP data

    Science.gov (United States)

    Taylor, Thomas E.; O'Dell, Christopher W.; Frankenberg, Christian; Partain, Philip T.; Cronk, Heather Q.; Savtchenko, Andrey; Nelson, Robert R.; Rosenthal, Emily J.; Chang, Albert Y.; Fisher, Brenden; Osterman, Gregory B.; Pollock, Randy H.; Crisp, David; Eldering, Annmarie; Gunson, Michael R.

    2016-03-01

    The objective of the National Aeronautics and Space Administration's (NASA) Orbiting Carbon Observatory-2 (OCO-2) mission is to retrieve the column-averaged carbon dioxide (CO2) dry air mole fraction (XCO2) from satellite measurements of reflected sunlight in the near-infrared. These estimates can be biased by clouds and aerosols, i.e., contamination, within the instrument's field of view. Screening of the most contaminated soundings minimizes unnecessary calls to the computationally expensive Level 2 (L2) XCO2 retrieval algorithm. Hence, robust cloud screening methods have been an important focus of the OCO-2 algorithm development team. Two distinct, computationally inexpensive cloud screening algorithms have been developed for this application. The A-Band Preprocessor (ABP) retrieves the surface pressure using measurements in the 0.76 µm O2 A band, neglecting scattering by clouds and aerosols, which introduce photon path-length differences that can cause large deviations between the expected and retrieved surface pressure. The Iterative Maximum A Posteriori (IMAP) Differential Optical Absorption Spectroscopy (DOAS) Preprocessor (IDP) retrieves independent estimates of the CO2 and H2O column abundances using observations taken at 1.61 µm (weak CO2 band) and 2.06 µm (strong CO2 band), while neglecting atmospheric scattering. The CO2 and H2O column abundances retrieved in these two spectral regions differ significantly in the presence of cloud and scattering aerosols. The combination of these two algorithms, which are sensitive to different features in the spectra, provides the basis for cloud screening of the OCO-2 data set.To validate the OCO-2 cloud screening approach, collocated measurements from NASA's Moderate Resolution Imaging Spectrometer (MODIS), aboard the Aqua platform, were compared to results from the two OCO-2 cloud screening algorithms. With tuning of algorithmic threshold parameters that allows for processing of ≃ 20-25 % of all OCO-2 soundings

  20. Orbiting Carbon Observatory-2 (OCO-2 cloud screening algorithms; validation against collocated MODIS and CALIOP data

    Directory of Open Access Journals (Sweden)

    T. E. Taylor

    2015-12-01

    Full Text Available The objective of the National Aeronautics and Space Administration's (NASA Orbiting Carbon Observatory-2 (OCO-2 mission is to retrieve the column-averaged carbon dioxide (CO2 dry air mole fraction (XCO2 from satellite measurements of reflected sunlight in the near-infrared. These estimates can be biased by clouds and aerosols within the instrument's field of view (FOV. Screening of the most contaminated soundings minimizes unnecessary calls to the computationally expensive Level 2 (L2 XCO2 retrieval algorithm. Hence, robust cloud screening methods have been an important focus of the OCO-2 algorithm development team. Two distinct, computationally inexpensive cloud screening algorithms have been developed for this application. The A-Band Preprocessor (ABP retrieves the surface pressure using measurements in the 0.76 μm O2 A-band, neglecting scattering by clouds and aerosols, which introduce photon path-length (PPL differences that can cause large deviations between the expected and retrieved surface pressure. The Iterative Maximum A-Posteriori (IMAP Differential Optical Absorption Spectroscopy (DOAS Preprocessor (IDP retrieves independent estimates of the CO2 and H2O column abundances using observations taken at 1.61 μm (weak CO2 band and 2.06 μm (strong CO2 band, while neglecting atmospheric scattering. The CO2 and H2O column abundances retrieved in these two spectral regions differ significantly in the presence of cloud and scattering aerosols. The combination of these two algorithms, which key off of different features in the spectra, provides the basis for cloud screening of the OCO-2 data set. To validate the OCO-2 cloud screening approach, collocated measurements from NASA's Moderate Resolution Imaging Spectrometer (MODIS, aboard the Aqua platform, were compared to results from the two OCO-2 cloud screening algorithms. With tuning to allow throughputs of ≃ 30 %, agreement between the OCO-2 and MODIS cloud screening methods is found

  1. Orbiting Carbon Observatory-2 (OCO-2) cloud screening algorithms; validation against collocated MODIS and CALIOP data

    Science.gov (United States)

    Taylor, T. E.; O'Dell, C. W.; Frankenberg, C.; Partain, P.; Cronk, H. Q.; Savtchenko, A.; Nelson, R. R.; Rosenthal, E. J.; Chang, A. Y.; Fisher, B.; Osterman, G.; Pollock, R. H.; Crisp, D.; Eldering, A.; Gunson, M. R.

    2015-12-01

    The objective of the National Aeronautics and Space Administration's (NASA) Orbiting Carbon Observatory-2 (OCO-2) mission is to retrieve the column-averaged carbon dioxide (CO2) dry air mole fraction (XCO2) from satellite measurements of reflected sunlight in the near-infrared. These estimates can be biased by clouds and aerosols within the instrument's field of view (FOV). Screening of the most contaminated soundings minimizes unnecessary calls to the computationally expensive Level 2 (L2) XCO2 retrieval algorithm. Hence, robust cloud screening methods have been an important focus of the OCO-2 algorithm development team. Two distinct, computationally inexpensive cloud screening algorithms have been developed for this application. The A-Band Preprocessor (ABP) retrieves the surface pressure using measurements in the 0.76 μm O2 A-band, neglecting scattering by clouds and aerosols, which introduce photon path-length (PPL) differences that can cause large deviations between the expected and retrieved surface pressure. The Iterative Maximum A-Posteriori (IMAP) Differential Optical Absorption Spectroscopy (DOAS) Preprocessor (IDP) retrieves independent estimates of the CO2 and H2O column abundances using observations taken at 1.61 μm (weak CO2 band) and 2.06 μm (strong CO2 band), while neglecting atmospheric scattering. The CO2 and H2O column abundances retrieved in these two spectral regions differ significantly in the presence of cloud and scattering aerosols. The combination of these two algorithms, which key off of different features in the spectra, provides the basis for cloud screening of the OCO-2 data set. To validate the OCO-2 cloud screening approach, collocated measurements from NASA's Moderate Resolution Imaging Spectrometer (MODIS), aboard the Aqua platform, were compared to results from the two OCO-2 cloud screening algorithms. With tuning to allow throughputs of ≃ 30 %, agreement between the OCO-2 and MODIS cloud screening methods is found to be

  2. Air temperature field distribution estimations over a Chinese mega-city using MODIS land surface temperature data: the case of Shanghai

    Science.gov (United States)

    Ma, Weichun; Zhou, Liguo; Zhang, Hao; Zhang, Yan; Dai, Xiaoyan

    2016-03-01

    The capability of obtaining spatially distributed air temperature data from remote sensing measurements is an improvement for many environmental applications focused on urban heat island, carbon emissions, climate change, etc. This paper is based on the MODIS/Terra and Aqua data utilized to study the effect of the urban atmospheric heat island in Shanghai, China. The correlation between retrieved MODIS land surface temperature (LST) and air temperature measured at local weather stations was initially studied at different temporal and spatial scales. Secondly, the air temperature data with spatial resolutions of 250 m and 1 km were estimated from MODIS LST data and in-situ measured air temperature. The results showed that there is a slightly higher correlation between air temperature and MODIS LST at a 250m resolution in spring and autumn on an annual scale than observed at a 1 km resolution. Although the distribution pattern of the air temperature thermal field varies in different seasons, the urban heat island (UHI) in Shanghai is characterized by a distribution pattern of multiple centers, with the central urban area as the primary center and the built-up regions in each district as the subcenters. This study demonstrates the potential not only for estimating the distribution of the air temperature thermal field from MODIS LST with 250 m resolution in spring and autumn in Shanghai, but also for providing scientific and effective methods for monitoring and studying UHI effect in a Chinese mega-city such as Shanghai.

  3. Seasonal variability of cloud optical depth over northwestern China derived from CERES/MODIS satellite measurements

    Institute of Scientific and Technical Information of China (English)

    Yonghang Chen; Hongtao Bai; Jianping Huang; Hua Zhang; Jinming Ge; Xiaodan Guan; Xiaoqin Mao

    2008-01-01

    The seasonal variability of cloud optical depth over northwestern China derived from Clouds and the Earth's Radiant Energy System (CERES) Single Scanner Footprint (SSF) Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) Edition 1B data from July 2002 to June 2004 is presented. The regions of interest are those with Asia monsoon influence, the Tianshan and Qilian Mountains, and the Taklimakan Desert. The results show that the instantaneous measurements presented here are much higher than the previous results derived from International Satellite Cloud Climatology Project (ISCCP) D2 monthly mean data. Generally the measurements of cloud optical depth are the highest in summer and the lowest in winter, however, Taklimakan Desert has the lowest measurements in autumn. The regional variation is quite significant over northwestern China.

  4. The Transition of High-Resolution NASA MODIS Sea Surface Temperatures into the WRF Environmental Modeling System

    Science.gov (United States)

    Case, Jonathan L.; Jedlove, Gary J.; Santos, Pablo; Medlin, Jeffrey M.; Rozumalski, Robert A.

    2009-01-01

    The NASA Short-term Prediction Research and Transition (SPoRT) Center has developed a Moderate Resolution Imaging Spectroradiometer (MODIS) sea surface temperature (SST) composite at 2-km resolution that has been implemented in version 3 of the National Weather Service (NWS) Weather Research and Forecasting (WRF) Environmental Modeling System (EMS). The WRF EMS is a complete, full physics numerical weather prediction package that incorporates dynamical cores from both the Advanced Research WRF (ARW) and the Non-hydrostatic Mesoscale Model (NMM). The installation, configuration, and execution of either the ARW or NMM models is greatly simplified by the WRF EMS to encourage its use by NWS Weather Forecast Offices (WFOs) and the university community. The WRF EMS is easy to run on most Linux workstations and clusters without the need for compilers. Version 3 of the WRF EMS contains the most recent public release of the WRF-NMM and ARW modeling system (version 3 of the ARW is described in Skamarock et al. 2008), the WRF Pre-processing System (WPS) utilities, and the WRF Post-Processing program. The system is developed and maintained by the NWS National Science Operations Officer Science and Training Resource Coordinator. To initialize the WRF EMS with high-resolution MODIS SSTs, SPoRT developed the composite product consisting of MODIS SSTs over oceans and large lakes with the NCEP Real-Time Global (RTG) filling data over land points. Filling the land points is required due to minor inconsistencies between the WRF land-sea mask and that used to generate the MODIS SST composites. This methodology ensures a continuous field that adequately initializes all appropriate arrays in WRF. MODIS composites covering the Gulf of Mexico, western Atlantic Ocean and the Caribbean are generated daily at 0400, 0700, 1600, and 1900 UTC corresponding to overpass times of the NASA Aqua and Terra polar orbiting satellites. The MODIS SST product is output in gridded binary-1 (GRIB-1) data

  5. A Real-Time MODIS Vegetation Composite for Land Surface Models and Short-Term Forecasting

    Science.gov (United States)

    Case, Jonathan L.; LaFontaine, Frank J.; Kumar, Sujay V.; Jedlovec, Gary J.

    2011-01-01

    The NASA Short-term Prediction Research and Transition (SPoRT) Center is producing real-time, 1- km resolution Normalized Difference Vegetation Index (NDVI) gridded composites over a Continental U.S. domain. These composites are updated daily based on swath data from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor aboard the polar orbiting NASA Aqua and Terra satellites, with a product time lag of about one day. A simple time-weighting algorithm is applied to the NDVI swath data that queries the previous 20 days of data to ensure a continuous grid of data populated at all pixels. The daily composites exhibited good continuity both spatially and temporally during June and July 2010. The composites also nicely depicted high greenness anomalies that resulted from significant rainfall over southwestern Texas, Mexico, and New Mexico during July due to early-season tropical cyclone activity. The SPoRT Center is in the process of computing greenness vegetation fraction (GVF) composites from the MODIS NDVI data at the same spatial and temporal resolution for use in the NASA Land Information System (LIS). The new daily GVF dataset would replace the monthly climatological GVF database (based on Advanced Very High Resolution Radiometer [AVHRR] observations from 1992-93) currently available to the Noah land surface model (LSM) in both LIS and the public version of the Weather Research and Forecasting (WRF) model. The much higher spatial resolution (1 km versus 0.15 degree) and daily updates based on real-time satellite observations have the capability to greatly improve the simulation of the surface energy budget in the Noah LSM within LIS and WRF. Once code is developed in LIS to incorporate the daily updated GVFs, the SPoRT Center will conduct simulation sensitivity experiments to quantify the impacts and improvements realized by the MODIS real-time GVF data. This presentation will describe the methodology used to develop the 1-km MODIS NDVI composites and

  6. MODIS-VIIRS Continuity: The Impact of Spatial Sampling on Global Land (Level-2) Products

    Science.gov (United States)

    Pahlevan, N.; Devadiga, S.; Lin, G.; Wolfe, R. E.; Roman, M. O.; Xiong, X.

    2014-12-01

    The Visible Infrared Imaging Radiometer Suite (VIIRS) onboard Suomi-NPP (S-NPP) has been providing daily global observations of the Earth surface since early 2012. With the decade-long observations made by MODIS onboard Terra and Aqua, one of the goals of the S-NPP mission is to provide continuity in producing land products that have been generated using heritage MODIS observations. The Land Data Operational Products Evaluation (LDOPE) team uses MODIS-derived products to evaluate land products obtained from VIIRS top-of-atmosphere (TOA) measurements generated through the Land Product Evaluation and Analysis Tool Element (LPEATE). However, due to inherent differences in their observation methods and the corresponding algorithms and post-processing techniques, the products generated from MODIS and VIIRS retain some discrepancies. Amongst all the differences between the two wide-swath radiometers, this study aims at analyzing the impact of differences in the corresponding spatial sampling. In particular, the VIIRS unique sampling scheme can introduce relative biases when comparing products (or observations) obtained from the two sensors. We use Landsat-8's Operational Land Imager (Level-1T data) scenes acquired within a set of 10 x 10 degree, i.e., "Golden tiles" (used for evaluation purposes by LDOPE) to examine how the discrepancies in the spatial responses manifest in measured radiances on a daily basis (for 16 days). The (band-detector averaged) prelaunch Line Spread Functions (LSFs) were used to represent spatial responses for each sensor. Although the impact of differences in sensors' spatial responses depends heavily on the spatial heterogeneity of a region-of-interest, the initial results, on average, indicate up to 0.8% and 5% difference (at the swath level) in the TOA radiances and TOA-based NDVI, respectively. The disparity (calculated for three sample scenes collected over the Golden sites) differs for different days (orbital configurations) and for

  7. Environmental factors that determine the occurrence and seasonal dynamics of Aphanizomenon flos-aquae

    Directory of Open Access Journals (Sweden)

    Yoshimasa YAMAMOTO

    2009-02-01

    Full Text Available This study investigated the seasonal dynamics of two populations of Aphanizomenon flos-aquae Ralfs ex Bornet & Flahault var. flos-aquae and four populations of A. flos-aquae var. klebahnii Elenkin in eutrophic water bodies over 1 year from February 2006 to January 2007. The growth of A. flos-aquae var. flos-aquae was promoted at high temperatures even if in one case the biomass development was very low when other co-occurring cyanoprokaryotes (Anabaena spp. and Microcystis spp. were abundant. In contrast, the highest density of the other population of A. flos-aquae var. flos-aquae was observed in August when the population density of M. aeruginosa (Kützing Kützing reached an annual peak. A. flos-aquae var. flos-aquae usually bloomed in summer but could also tolerate low temperatures in the winter, and was present in relatively high densities. The populations of A. flos-aquae var. klebahnii observed in this study can be divided into three groups based on preferred temperature; three populations increased in winter, and the other increased in summer. Large biomasses of the low-temperature-adapted A. flos-aquae were observed mainly during winter when population densities of co-occurring cyanoprokaryotes (Anabaena spp., Microcystis spp. and Planktothrix raciborskii (Woloszynska Anagnostidis & Komárek were relatively low or almost absent. The increase in or existence of cooccurring cyanoprokaryotes during the summer resulted in a decrease of the A. flos-aquae population density. It was revealed that high temperatures (20-25 °C are suitable for maintaining A. flos-aquae var. klebahnii strains isolated from the study ponds, implying that low-temperature-adapted A. flos-aquae can grow over a wide range of water temperatures. The high-temperatureadapted A. flos-aquae var. klebahnii co-existed with M. aeruginosa during summer; however, its peak population density was significantly lower than those in previous years when M. aeruginosa was absent

  8. Optical properties of aerosol contaminated cloud derived from MODIS instrument

    Science.gov (United States)

    Mei, Linlu; Rozanov, Vladimir; Lelli, Luca; Vountas, Marco; Burrows, John P.

    2016-04-01

    The presence of absorbing aerosols above/within cloud can reduce the amount of up-welling radiation in visible (VIS) and short-wave infrared and darken the spectral reflectance when compared with a spectrum of a clean cloud observed by satellite instruments (Jethva et al., 2013). Cloud properties retrieval for aerosol contaminated cases is a great challenge. Even small additional injection of aerosol particles into clouds in the cleanest regions of Earth's atmosphere will cause significant effect on those clouds and on climate forcing (Koren et al., 2014; Rosenfeld et al., 2014) because the micro-physical cloud process are non-linear with respect to the aerosol loading. The current cloud products like Moderate Resolution Imaging Spectroradiometer (MODIS) ignoring the aerosol effect for the retrieval, which may cause significant error in the satellite-derived cloud properties. In this paper, a new cloud properties retrieval method, considering aerosol effect, based on the weighting-function (WF) method, is presented. The retrieval results shows that the WF retrieved cloud properties (e.g COT) agrees quite well with MODIS COT product for relative clear atmosphere (AOT ≤ 0.4) while there is a large difference for large aerosol loading. The MODIS COT product is underestimated for at least 2 - 3 times for AOT>0.4, and this underestimation increases with the increase of AOT.

  9. Reducing the Discrepancy Between ASTER and MODIS Land Surface Temperature Products

    Directory of Open Access Journals (Sweden)

    Changqing Ke

    2007-12-01

    Full Text Available Human-induced global warming has significantly increased the importance ofsatellite monitoring of land surface temperature (LST on a global scale. The MODerate-resolution Imaging Spectroradiometer (MODIS provides a 1-km resolution LST productwith almost daily coverage of the Earth, invaluable to both local and global change studies.The Advanced Spaceborne Thermal Emission Reflection Radiometer (ASTER provides aLST product with a high spatial resolution of 90-m and a 16-day recurrent cycle,simultaneously acquired at the same height and nadir view as MODIS. ASTER andMODIS are complementary in resolution, offering a unique opportunity for scale-relatedstudies. ASTER and MODIS LST have been widely used but the errors in LST were mostlydisregarded. Correction of ASTER-to-MODIS LST discrepancies is essential for studiesreliant upon the joint use of these sensors. In this study, we compared three correctionapproaches: the Wan et al.’s approach, the refined Wan et al.’s approach, and thegeneralized split window (GSW algorithm based approach. The Wan et al.’s approachcorrects the MODIS 1-km LST using MODIS 5-km LST. The refined approach modifiesthe Wan et al.’s approach through incorporating ASTER emissivity and MODIS 5-km data.The GSW algorithm approach does not use MODIS 5-km but only ASTER emissivity data. We examined the case over a semi-arid terrain area for the part of the Loess Plateau of China. All the approaches reduced the ASTER-to-MODIS LST discrepancy effectively. With terrain correction, the original ASTER-to-MODIS LST difference reduced from 2.7±1.28 K to -0.1±1.87 K for the Wan et al.’s approach, 0.2±1.57 K for the refined approach, and 0.1±1.33 K for the GSW algorithm based approach. Among all the approaches, the GSW algorithm based approach performed best in terms of mean, standard deviation, root mean square root, and correlation coefficient.

  10. Aqua-vanadyl ion interaction with Nafion® membranes

    Directory of Open Access Journals (Sweden)

    Vijayakumar eMurugesan

    2015-03-01

    Full Text Available Lack of comprehensive understanding about the interactions between Nafion membrane and battery electrolytes prevents the straightforward tailoring of optimal materials for redox flow battery applications. In this work, we analyzed the interaction between aqua-vanadyl cation and sulfonic sites within the pores of Nafion membranes using combined theoretical and experimental X-ray spectroscopic methods. Molecular level interactions namely solvent share and contact pair mechanisms are discussed based on Vanadium and Sulfur K-edge spectroscopic analysis.

  11. Characterizing 13 Years of Surface Water Variability from MODIS-based Near Real-Time Flood Mapping Products in the Indus River, Tonle Sap Lake, and Lake Chad.

    Science.gov (United States)

    Slayback, D. A.; Brakenridge, G. R.; Policelli, F. S.

    2015-12-01

    Driven by an increase in extreme weather events in a warming world, flooding appears to be increasing in many regions. Since 2012, we have been using the twice-daily near-global observations of the two MODIS instruments to operate a near real-time flood mapping capability. Primarily intended to support disaster response efforts, our system generates daily near-global maps of flood water extent, at 250 m resolution. Although cloud cover is a challenge, the twice-daily coverage from the Terra and Aqua satellites helps to capture most major events. We use the MOD44W product (the "MODIS 250-m land-water mask") to differentiate "normal" water from flood water. Products from the system are freely available, and used by disaster response agencies and academic and industry researchers. An open question, however, is: how "normal" are recently observed floods? Destructive and — as reported by the press — record floods seem to be occurring more and more frequently. With the MODIS archive going back to 1999 (Terra satellite) and 2002 (Aqua satellite), we now have more than a decade of twice-daily near-global observations to begin answering this question. Although the 13 years of available twice-daily data (2002-2015) are not sufficient to fully characterize surface water normals (e.g., 100-year floods), we can start examining recent trends in surface water extent and flood frequency. To do so, we have back-processed our surface water product through mid-2002 (Aqua launch) for a few regions, and have used this to evaluate the variability in surface water extent and flood frequency. These results will eventually feed back into an improved characterization of flood water in our near real-time flood product. Here we will present results on trends in surface water extent and flood frequency for a few regions, including the Indus in Pakistan, the Tonle Sap lake in Cambodia, and lake Chad in Africa.

  12. Assessment of MODIS-Aqua chlorophyll-a algorithms in coastal and shelf waters of the eastern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Tilstone, G.H.; Lotliker, A.A.; Miller, P.I.; Ashraf, P.M.; SrinivasaKumar, T.; Suresh, T.; Ragavan, B.R.; Menon, H.B.

    shelf is influenced by river run-off, winter convection and monsoon upwelling. Bio-optical parameters were measured along this coast from March 2009 to June 2011, to characterise the optical water type and validate three Chlorophyll-a (Chl-a) algorithms...

  13. Examining Lake Michigan Spring Euphotic Depth (Zeu) Anomalies: Utilizing 10 Years of MODIS-Aqua Data at 4 Kilometer Resolution

    Science.gov (United States)

    Acker, James G.

    2013-01-01

    Examination of ten years of euphotic depth anomalies in Lake Michigan during the months of March-June indicates the following: The well-known and frequently observed occurrence of a turbidity feature in the southern part of Lake Michigan during the spring season has become less common during the period 2003-2012. Overall, the clarity of Lake Michigan water in the southern end of the lake appears to have increased spring season over the period 2003-2012. Euphotic depth can be used as a primary indicator of changes in Lake Michigan lacustrine optics, and for other large lakes. Unique events, such as the heavy rains in June 2008, can have a distinct signature in the euphotic depth anomaly distribution in Lake Michigan.

  14. Cartografía de incendios forestales en Paraguay mediante imágenes AQUA-MODIS

    OpenAIRE

    Martín Isabel, M. Pilar; Rejalaga Noguera, Larissa K.

    2010-01-01

    Uno de los principales problemas ambientales que se plantean actualmente a nivel mundial es la pérdida de los recursos forestales ocasionada por el fuego. La gran extensión y dificultad de acceso a muchas de las zonas afectadas, especialmente en zonas tropicales, hace difícil la cuantificación del daño que provocan los incendios forestales. La cartografía operativa de las áreas quemadas requiere disponer de métodos fiables y rápidos que permitan obtener resultados en un margen relativament...

  15. GHRSST Level 4 RTO Aqua MODIS-AMSRE Night North America Regional Blended Sea Surface Temperature Analysis (GDS version 1)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A Group for High Resolution Sea Surface Temperature (GHRSST) Level 4 sea surface temperature analysis produced daily on an operational basis at the JPL Physical...

  16. GHRSST Level 4 RTO Aqua MODIS-AMSRE Day North America Regional Blended Sea Surface Temperature Analysis (GDS version 1)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A Group for High Resolution Sea Surface Temperature (GHRSST) Level 4 sea surface temperature analysis produced daily on an operational basis at the JPL Physical...

  17. ANALISIS PERUBAHAN SUHU PERMUKAAN TANAH DENGAN MENGGUNAKAN CITRA SATELIT TERRA DAN AQUA MODIS (STUDI KASUS : DAERAH KABUPATEN MALANG DAN SURABAYA)

    OpenAIRE

    Dawamul Arifin; Bangun Muljo Sukojo

    2015-01-01

    Salah satu dampak pemanasan global adalah terjadinya perubahan iklim yang signifikan. Perubahan iklim yang terjadi mengakibatkan bencana hidro-meteorologi yaitu kekeringan dimana salah satu faktor terjadinya adalah peningkatan suhu permukaan tanah. Data suhu permukaan tanah di Indonesia diperoleh dari stasiun pengamat cuaca yang didapatkan dengan menggunakan termometer yang dipasang dalam sangkar cuaca. Data yang diperoleh dari pengamatan termometer ini hanya mewakili daerah sekitar.Dalam pen...

  18. Spectral Inpainting for the Restoration of Missing Data from Multispectral Satellite Sensors: Case study on Aqua MODIS Band 6

    OpenAIRE

    Bouali, Marouan; Ladjal, Saïd

    2011-01-01

    In this letter, we introduce an algorithm for the restoration of missing data from multi- spectral satellite imagery. The proposed approach combines two simple principles; non local or neighborhood filters used in the context of still image denoising/inpainting and spectral matching techniques based on spectral similarity measures and required for the classification of hyperspectral images. The resulting semi-physical approach, refered to as spectral inpaint- ing, is applied to the particular i...

  19. Monitoring NEON terrestrial sites phenology with daily MODIS BRDF/albedo product and landsat data

    Science.gov (United States)

    The MODerate resolution Imaging Spectroradiometer (MODIS) Bidirectional Reflectance Distribution Function (BRDF) and albedo products (MCD43) have already been in production for more than a decade. The standard product makes use of a linear “kernel-driven” RossThick-LiSparse Reciprocal (RTLSR) BRDF m...

  20. MODIS 3 km aerosol product: algorithm and global perspective

    OpenAIRE

    Remer, L. A.; Mattoo, S; R. C. Levy; Munchak, L.

    2013-01-01

    After more than a decade of producing a nominal 10 km aerosol product based on the dark target method, the MODIS aerosol team will be releasing a nominal 3 km product as part of their Collection 6 release. The new product differs from the original 10 km product only in the manner in which reflectance pixels are ingested, organized and selected by the aerosol algorithm. Overall, the 3 km product closely mirrors the 10 km product. However, the finer resolution product is able to retrieve over o...

  1. Estimating terra MODIS polarization effect using ocean data

    Science.gov (United States)

    Wald, Andrew; Brinkmann, Jake; Wu, Aisheng; Xiong, Jack

    2016-05-01

    Terra MODIS has been known since pre-launch to have polarization sensitivity, particularly in shortest-wavelength bands 8 and 9. On-orbit reflectance trending of pseudo-invariant sites show a variation in reflectance as a function of band and scan mirror angle of incidence consistent with time-dependent polarization effects from the rotating doublesided scan mirror. The MODIS Characterization Support Team [MCST] estimates the Mueller matrix trending from this variation as observed from a single desert site, but this effect is not included in Collection 6 [C6] calibration. Here we extend the MCST's current polarization sensitivity monitoring to two ocean sites distributed over latitude to help estimate the uncertainties in the derived Mueller matrix. The Mueller matrix elements derived for polarization-sensitive Band 8 for a given site are found to be fairly insensitive to surface brdf modeling. The site-to-site variation is a measure of the uncertainty in the Mueller estimation. Results for band 8 show that the polarization correction reduces mirror-side striping by up to 50% and reduces the instrument polarization effect on reflectance time series of an ocean target.

  2. Retrieval of Aerosol Optical Properties under Thin Cirrus from MODIS

    Science.gov (United States)

    Lee, Jaehwa; Hsu, Nai-Yung Christina; Bettenhausen, Corey; Sayer, Andrew Mark.

    2014-01-01

    Retrieval of aerosol optical properties using shortwave bands from passive satellite sensors, such as MODIS, is typically limited to cloud-free areas. However, if the clouds are thin enough (i.e. thin cirrus) such that the satellite-observed reflectance contains signals under the cirrus layer, and if the optical properties of this cirrus layer are known, the TOA reflectance can be corrected for the cirrus layer to be used for retrieving aerosol optical properties. To this end, we first correct the TOA reflectances in the aerosol bands (0.47, 0.55, 0.65, 0.86, 1.24, 1.63, and 2.12 micron for ocean algorithm and 0.412, 0.47, and 0.65 micron for deep blue algorithm) for the effects of thin cirrus using 1.38 micron reflectance and conversion factors that convert cirrus reflectance in 1.38 micron band to those in aerosol bands. It was found that the conversion factors can be calculated by using relationships between reflectances in 1.38 micron band and minimum reflectances in the aerosol bands (Gao et al., 2002). Refer to the example in the figure. Then, the cirrus-corrected reflectance can be calculated by subtracting the cirrus reflectance from the TOA reflectance in the optically thin case. A sensitivity study suggested that cloudy-sky TOA reflectances can be calculated with small errors in the form of simple linear addition of cirrus-only reflectances and clear-sky reflectances. In this study, we correct the cirrus signals up to TOA reflectance at 1.38 micron of 0.05 where the simple linear addition is valid without extensive radiative transfer simulations. When each scene passes the set of tests shown in the flowchart, the scene is corrected for cirrus contamination and passed into aerosol retrieval algorithms.

  3. Long-term (2002-2014) evolution and trend in Collection 5.1 Level-2 aerosol products derived from the MODIS and MISR sensors over the Chinese Yangtze River Delta

    Science.gov (United States)

    Kang, Na; Kumar, K. Raghavendra; Hu, Kang; Yu, Xingna; Yin, Yan

    2016-11-01

    The present study aims to investigate spatio-temporal evolution and trend in the aerosol optical properties (aerosol optical depth, AOD; Ångström exponent, AE), qualitatively identify different types and origin of aerosols over an urban city, Nanjing in the Yangtze River Delta, East China. For this purpose, the Collection 5.1 Level-2 data obtained from the Moderate resolution Imaging Spectroradiometer (MODIS) sensor onboard Terra and Aqua satellites and the Multi-angle Imaging Spectroradiometer (MISR) instrument for the period between 2002 and 2014 have been analyzed. An inter-comparison and validation of AOD were performed against the AOD measurements obtained from the ground-based Aerosol Robotic Network (AERONET) sunphotometer. The MODIS AOD550 exhibited wide spatial and temporal distributions over East China, while MISR AOD555 was consistently lower than that of Terra and Aqua AOD550 values. The temporal variations (monthly and seasonal mean) of MODIS (Terra and Aqua) and MISR AOD values exhibited a similar pattern. The seasonal mean AOD550 (AE470-660) was found to be maximum with 0.97 ± 0.48 during summer (1.16 ± 0.33 in summer) and a minimum of 0.61 ± 0.28 during the winter season (0.80 ± 0.28 in spring). The annual mean Terra AOD550 at Nanjing showed a strong decreasing trend (- 0.70% year- 1), while the Aqua exhibited a slight increasing trend (+ 0.01 year- 1) during the study period. Seasonal air mass back-trajectories obtained from the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model were also computed to infer on the transport component over the study region. Different aerosol types were identified via the relationship between AOD550 and fine mode fraction, which reveals that the biomass burning/urban-industrial type aerosols (desert dust) are abundant over the region in summer (spring), apart from the mixed aerosol type.

  4. Vegetation/Soil Synthesis Water Index Using MODIS Data

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    In consideration of the spectral character of MODIS (Moderate Resolution Imaging Spectroradiometer) data and the reflective spectrum of vegetation and soil, NDVI (Normalized Difference Vegetation Index) and NDWI (Normalized Difference Water Index) are deduced using one visible band (0.66μm) and two near-infrared bands (0.86μm, 1.24 μm). Vegetation canopy temperature is derived using two thermal infrared bands (8.6 μm and 11μm). Then the vegetation/soil synthesis water index (VSWI) is acquired through analyzing the coupling character of three indexes which can reflect the water condition of vegetation. Finally, the synthesis index is verified by equivalent water content of a single leaf. The matching results show that the synthesis index is directly proportional to the modeled data, which means that the vegetation water content can be reflected using the synthesis index effectively.

  5. ATMOSPHERIC AEROSOL VARIABILITY OVER THE REGION OF SAN PEDRO MÁRTIR FROM MODIS DATA

    Directory of Open Access Journals (Sweden)

    Mario R. Araiza Quijano

    2011-01-01

    Full Text Available Se presenta un estudio del espesoróptico del aerosol atmosférico (AOT por sus siglas en inglés en el sitio astronómico de San Pedro Mártir, B. C., México durante el periodo 2000-2008. Las mediciones del AOT se realizaron con el instrumento Moderate Resolution Imaging Spectroradiometer (MODIS, a bordo de los satélites Aqua y Terra de la NASA. Se han identificado valores característicos estacionales que muestran un comportamiento de mayor transparencia atmosférica durante el otoño. Las mejores condiciones de transparencia atmosférica ocurren durante octubre y noviembre. El comportamiento anual durante 2000-2008 del AOT de MODIS da valores promedio de 0.147±0.103, 0.128±0.090, 0.115±0.081, 0.087 ± 0.066 en 4700, 5500, 6600 and 21300 A, respectivamente. Utilizando estos valores promedio se analizó la dependencia del AOT con la longitud de onda, y se encontró que OIR 0.31 ± 0.06 y la relación 0.00610.31 para dispersión por aerosoles en el sitio de San Pedro Mártir.

  6. A Method for Deriving the Boundary Layer Mixing Height from MODIS Atmospheric Profile Data

    Directory of Open Access Journals (Sweden)

    Xueliang Feng

    2015-09-01

    Full Text Available The planetary boundary layer is the medium of energy, moisture, momentum and pollutant exchange between the surface and the atmosphere. In this paper, a method to derive the boundary layer mixing height (MH was introduced and applied over the Heihe river basin. Atmospheric profiles from the MODerate Resolution Imaging Sepctroradiometer (MODIS instrument onboard the NASA-Aqua satellite were used for the high spatial resolution of this method. A gap-filling method was used to replace missing MODIS data. In situ MH data were also calculated from HIWATER (Heihe Watershed Allied Telemetry Experimental Research and WATER (Watershed Allied Telemetry Experimental Research observational radiosonde sounding data from 2008 and 2012 using the Richardson number method combined with a subjective method. The MH occurs where there is an abrupt decrease in the MR (water vapor mixing ratio. The minimum vertical gradient of the MR is used to determine the MH. The method has an average RMSE of 370 m under clear skies and convective conditions. The seasonal variation in the MH at the Gaoya radiosonde station is also presented. The study demonstrates that remote sensing methodologies can successfully estimate the MH without the help of field measurements.

  7. MODIS aerosol product at 3 km spatial resolution for urban and air quality studies

    Science.gov (United States)

    Mattoo, S.; Remer, L. A.; Levy, R. C.; Holben, B. N.; Smirnov, A.

    2008-12-01

    The MODerate resolution Imaging Spectroradiometer (MODIS) aboard the Terra and Aqua satellites has been producing an aerosol product since early 2000. The original product reports aerosol optical depth and a variety of other aerosol parameters at a spatial resolution of 10 km over both land and ocean. The 10 km product is actually constructed from 500 m pixels, which permits a strict selection process to choose the "best" or "cleanest" pixels in each 10 km square for use in the aerosol retrieval. Thus, the original 10 km product provides a useful product, accurate in many applications. However, the 10 km product can miss narrow aerosol plumes and the spatial variability associated with urban air pollution. The MODIS aerosol team will be introducing a finer resolution aerosol product over land regions in the next release of the product (Collection 6). The new product will be produced at 3 km resolution. It is based on the same procedures as the original product and benefits from the same spatial variability criteria for finding and masking cloudy pixels. The 3 km product does capture the higher spatial variability associated with individual aerosol plumes. However, it is noisier than the 10 km product. Both products will be available operationally in Collection 6. The new 3km product offers new synergistic possibilities with PM2.5 monitoring networks, AERONET and various air quality models such as CMAQ.

  8. Feasibility of anomaly occurrence in aerosols time series obtained from MODIS satellite images during hazardous earthquakes

    Science.gov (United States)

    Akhoondzadeh, Mehdi; Jahani Chehrebargh, Fatemeh

    2016-09-01

    Earthquake is one of the most devastating natural disasters that its prediction has not materialized comprehensive. Remote sensing data can be used to access information which is closely related to an earthquake. The unusual variations of lithosphere, atmosphere and ionosphere parameters before the main earthquakes are considered as earthquake precursors. To date the different precursors have been proposed. This paper examines one of the parameters which can be derived from satellite imagery. The mentioned parameter is Aerosol Optical Depth (AOD) that this article reviews its relationship with earthquake. Aerosol parameter can be achieved through various methods such as AERONET ground stations or using satellite images via algorithms such as the DDV (Dark Dense Vegetation), Deep Blue Algorithm and SYNTAM (SYNergy of Terra and Aqua Modis). In this paper, by analyzing AOD's time series (derived from MODIS sensor on the TERRA platform) for 16 major earthquakes, seismic anomalies were observed before and after earthquakes. Before large earthquakes, rate of AOD increases due to the pre-seismic changes before the strong earthquake, which produces gaseous molecules and therefore AOD increases. Also because of aftershocks after the earthquake there is a significant change in AOD due to gaseous molecules and dust. These behaviors suggest that there is a close relationship between earthquakes and the unusual AOD variations. Therefore the unusual AOD variations around the time of earthquakes can be introduced as an earthquake precursor.

  9. New advances of MODY%MODY研究新进展

    Institute of Scientific and Technical Information of China (English)

    周姣姣; 李鸿

    2013-01-01

    青少年发病的成人型糖尿病(MODY)是一组青年起病的常染色体显性遗传病.目前,MODY按致病基因至少可分为13型:MODY1(肝细胞核因子4α,HNF4α),MODY2(葡萄糖激酶,GCK),MODY3(肝细胞核因子1α,HNF1α),MODY4(胰岛素启动因子1,IPF1),MODY5(肝细胞核因子1β,HNF1β),MODY6(神经元分化因子1,NEUROD1),MODY7(kruppel样因子11,KLF11),MODY8 (羧基酯脂肪酶,CEL),MODY9(成对盒基因4,PAX4),MODY10(胰岛素基因),MODY11(B淋巴细胞激酶,BLK),MODY12(ATP结合C家族8因子,ABCC8)和MODY13(内向整流性钾离子通道J家族11因子,KCNJ11).其发病机制、临床表现和治疗方法各有不同.%Maturity-onset diabetes of the young (MODY) is a young-onset diabetes mellitus with a autosomal-dominant mode of transmission.At least thirteen subtypes with distinct genetic aetiologies have been reported:MODY1 (hepatocyte nuclear factor 4α,HNF4α),MODY2 (glucokinase,GCK),MODY3 (hepatocyte nuclear factor 1α,HNF1α),MODY4 (insulin promoter factor 1,IPF1),MODY5 (hepatocyte nuclear factor 1β,HNF1β),MODY6 (neurogenic differentiation factor 1,NEUROD 1),MODY7 (kruppel-like factor 11,KLF11),MODY8 (carboxyl-ester lipase,CEL),MODY9 (paired-homeodomain transcription factor,PAX4),MODY10 (insulin gene),MODY1 1 (B-lymphocyte kinase,BLK),MODY1 2 (ATP-binding cassette,sub-family C member 8,ABCC8,and MODY13 (potassium inwardly-rectifying channel,subfamily J,member 11,KCNJ11).The etiopathogenisis,clinic phenotype and treatment of them are different.

  10. A Review on the Research and Application of AquaCrop Model%AquaCrop作物模型应用研究进展

    Institute of Scientific and Technical Information of China (English)

    王连喜; 吴建生; 李琪; 顾嘉熠; 薛红喜

    2015-01-01

    介绍了AquaCrop模型的基本原理以及研究和应用进展,重点介绍了AquaCrop模型的应用情况.AquaCrop模型在作物灌溉管理、种植制度、未来气候情景模拟中的应用已取得了较好成果.总结了AquaCrop模型当前应用应注意的问题,指出:AquaCrop模型的研究集中于单点尺度,在国内的研究多集中于模型的校正与验证,模型参数在我国的适用性还有待进一步验证;在严重水分胁迫条件下,会影响AquaCrop模型的模拟性能.最后,提出了未来发展的几点建议,以期为AquaCrop模型今后在我国的农业生产实践中起到指导作用.

  11. Predicting Clear-Sky Reflectance Over Snow/Ice in Polar Regions

    Science.gov (United States)

    Chen, Yan; Sun-Mack, Sunny; Arduini, Robert F.; Hong, Gang; Minnis, Patrick

    2015-01-01

    Satellite remote sensing of clouds requires an accurate estimate of the clear-sky radiances for a given scene to detect clouds and aerosols and to retrieve their microphysical properties. Knowing the spatial and angular variability of clear-sky albedo is essential for predicting clear-sky radiance at solar wavelengths. The Clouds and the Earth's Radiant Energy System (CERES) Project uses the nearinfrared (NIR; 1.24, 1.6 or 2.13 micrometers), visible (VIS; 0.63 micrometers) and vegetation (VEG; 0.86 micrometers) channels available on the Terra and Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) to help identify clouds and retrieve their properties in both snow-free and snow-covered conditions. Thus, it is critical to have reliable distributions of clear-sky albedo for all of these channels. In CERES Edition 4 (Ed4), the 1.24-micrometer channel is used to retrieve cloud optical depth over snow/ice-covered surfaces. Thus, it is especially critical to accurately predict the 1.24-micrometer clear-sky albedo alpha and reflectance rho for a given location and time. Snow albedo and reflectance patterns are very complex due to surface texture, particle shapes and sizes, melt water, and vegetation protrusions from the snow surface. To minimize those effects, this study focuses on the permanent snow cover of Antarctica where vegetation is absent and melt water is minimal. Clear-sky albedos are determined as a function of solar zenith angle (SZA) from observations over all scenes determined to be cloud-free to produce a normalized directional albedo model (DRM). The DRM is used to develop alpha(SZA=0 degrees) on 10 foot grid for each season. These values provide the basis for predicting r at any location and set of viewing & illumination conditions. This paper examines the accuracy of this approach for two theoretical snow surface reflectance models.

  12. Validation of MODIS snow cover images over Austria

    OpenAIRE

    Parajka, J.; Blöschl, G.

    2006-01-01

    This study evaluates the Moderate Resolution Imaging Spectroradiometer (MODIS) snow cover product over the territory of Austria. The aims are (a) to analyse the spatial and temporal variability of the MODIS snow product classes, (b) to examine the accuracy of the MODIS snow product against in situ snow depth data, and (c) to identify the main factors that may influence the MODIS classification accuracy. We use daily MODIS grid maps (version 4) and daily snow depth measurements at 754 climate ...

  13. Validation of MODIS snow cover images over Austria

    OpenAIRE

    Parajka, J.; Blöschl, G.

    2006-01-01

    International audience This study evaluates the Moderate Resolution Imaging Spectroradiometer (MODIS) snow cover product over the territory of Austria. The aims are (a) to analyse the spatial and temporal variability of the MODIS snow product classes, (b) to examine the accuracy of the MODIS snow product against in situ snow depth data, and (c) to identify the main factors that may influence the MODIS classification accuracy. We use daily MODIS grid maps (version 4) and daily snow depth me...

  14. Remote sensing of cloud, aerosol and water vapor properties from the Moderate Resolution Imaging Spectrometer (MODIS)

    Science.gov (United States)

    King, M. D.

    1992-01-01

    The Moderate Resolution Imaging Spectrometer (MODIS) is an Earth-viewing sensor being developed as a facility instrument for the Earth Observing System (EOS) to be launched in the late 1990s. MODIS consists of two separate instruments that scan a swath width sufficient to provide nearly complete global coverage every two days from a polar-orbiting, Sun-synchronous, platform at an altitude of 705 km. Of primary interest for studies of atmospheric physics is the MODIS-N (nadir) instrument which will provide images in 36 spectral bands between 0.415 and 14.235 micrometers with spatial resoulutions of 250 m (2 bands), 500 m (5 bands) and 1000 m (29 bands). These bands have been carefully selected to enable advanced studies of land, ocean and atmosperhic processes. The intent of this lecture is to describe the current status of MODIS-N and its companion instrument MODIS-T (tilt), a tiltable cross-track scanning radiometer with 32 uniformly spaced channels between 0.410 and 0.875 micrometers, and to describe the physical principles behind the development of MODIS for the remote sensing of atmospheric properties. Primary emphasis will be placed on the main atmospheric applications of determining the optical, microphysical and physical properties of clouds and aerosol particles form spectral-reflection and thermal-emission measurements. In addition to cloud and aerosol properties, MODIS-N will be utilized for the determination of the total precipitable water vapor over land and atmospheric stability. The physical principles behind the determination of each of these atmospheric products will be described herein.

  15. Characterization of dust aerosols in the infrared from IASI and comparison with PARASOL, MODIS, MISR, CALIOP, and AERONET observations

    Directory of Open Access Journals (Sweden)

    S. Peyridieu

    2012-09-01

    Full Text Available Infrared Atmospheric Sounder Interferometer (IASI observations covering the period from July 2007 to December 2011 are interpreted in terms of monthly mean, 1°×1°, 10 μm dust Aerosol Optical Depth (AOD, mean altitude and coarse mode effective radius. The geographical study area includes the northern tropical Atlantic and the north-west Arabian Sea, both characterized by strong, regular dust events. The method developed relies on the construction of Look-Up-Tables computed for a large selection of atmospheric situations and observing conditions. At regional scale, a good agreement is found between IASI-retrieved 10 μm AOD and total visible optical depth at 550 nm from either the Moderate resolution Imaging Spectroradiometer (MODIS/Aqua or Terra, or the Multi-angle Imaging SpectroRadiometer (MISR, or the Polarization and Anisotropy of Reflectances for Atmospheric Science coupled with Observations from a Lidar (PARASOL. Taking into account the ratio existing between infrared and visible AODs, the diversity between the different 550 nm AODs is similar to the difference between these and the IASI AODs. The infrared AOD to visible AOD ratio, partly reflecting the varying distribution of the dust layer between the dust coarse mode particles seen by IASI, and the fine mode seen by the other instruments, is found to vary with the region observed with values close to already published values. Comparisons between the climatologies of the 10 μm IASI AOD and of the PARASOL non-spherical coarse mode AOD at 865 nm, both expected to be representative of the dust coarse mode, lead to conclusions differing according to the region considered. These differences are discussed in the light of the MODIS Angström exponent (865–550 nm. At local scale, around six Aerosol Robotic Network (AERONET sites, close or far from the dust sources, a similar satisfactory agreement is found between IASI and the visible AODs and the differences between these products are

  16. A comprehensive assessment of the correlations between field crop yields and commonly used MODIS products

    Science.gov (United States)

    Johnson, David M.

    2016-10-01

    An exploratory assessment was undertaken to determine the correlation strength and optimal timing of several commonly used Moderate Resolution Imaging Spectroradiometer (MODIS) composited imagery products against crop yields for 10 globally significant agricultural commodities. The crops analyzed included barley, canola, corn, cotton, potatoes, rice, sorghum, soybeans, sugarbeets, and wheat. The MODIS data investigated included the Normalized Difference Vegetation Index (NDVI), Fraction of Photosynthetically Active Radiation (FPAR), Leaf Area Index (LAI), and Gross Primary Production (GPP), in addition to daytime Land Surface Temperature (DLST) and nighttime LST (NLST). The imagery utilized all had 8-day time intervals, but NDVI had a 250 m spatial resolution while the other products were 1000 m. These MODIS datasets were also assessed from both the Terra and Aqua satellites, with their differing overpass times, to document any differences. A follow-on analysis, using the Terra 250 m NDVI data as a benchmark, looked at the yield prediction utility of NDVI at two spatial scales (250 m vs. 1000 m), two time precisions (8-day vs. 16-day), and also assessed the Enhanced Vegetation Index (EVI, at 250 m, 16-day). The analyses spanned the major farming areas of the United States (US) from the summers of 2008-2013 and used annual county-level average crop yield data from the US Department of Agriculture as a basis. All crops, except rice, showed at least some positive correlations to each of the vegetation related indices in the middle of the growing season, with NDVI performing slightly better than FPAR. LAI was somewhat less strongly correlated and GPP weak overall. Conversely, some of the crops, particularly canola, corn, and soybeans, also showed negative correlations to DLST mid-summer. NLST, however, was never correlated to crop yield, regardless of the crop or seasonal timing. Differences between the Terra and Aqua results were found to be minimal. The 1000 m

  17. Improved Topographic Normalization for Landsat TM Images by Introducing the MODIS Surface BRDF

    OpenAIRE

    Yanli Zhang; Xin Li; Jianguang Wen; Qinhuo Liu; Guangjian Yan

    2015-01-01

    In rugged terrain, the accuracy of surface reflectance estimations is compromised by atmospheric and topographic effects. We propose a new method to simultaneously eliminate atmospheric and terrain effects in Landsat Thematic Mapper (TM) images based on a 30 m digital elevation model (DEM) and Moderate Resolution Imaging Spectroradiometer (MODIS) atmospheric products. Moreover, we define a normalized factor of a Bidirectional Reflectance Distribution Function (BRDF) to convert the sloping pix...

  18. Aerosol retrieval algorithm for the characterization of local aerosol using MODIS L1B data

    International Nuclear Information System (INIS)

    Atmospheric aerosol plays an important role in radiation budget, climate change, hydrology and visibility. However, it has immense effect on the air quality, especially in densely populated areas where high concentration of aerosol is associated with premature death and the decrease of life expectancy. Therefore, an accurate estimation of aerosol with spatial distribution is essential, and satellite data has increasingly been used to estimate aerosol optical depth (AOD). Aerosol product (AOD) from Moderate Resolution Imaging Spectroradiometer (MODIS) data is available at global scale but problems arise due to low spatial resolution, time-lag availability of AOD product as well as the use of generalized aerosol models in retrieval algorithm instead of local aerosol models. This study focuses on the aerosol retrieval algorithm for the characterization of local aerosol in Hong Kong for a long period of time (2006-2011) using high spatial resolution MODIS level 1B data (500 m resolution) and taking into account the local aerosol models. Two methods (dark dense vegetation and MODIS land surface reflectance product) were used for the estimation of the surface reflectance over land and Santa Barbara DISORT Radiative Transfer (SBDART) code was used to construct LUTs for calculating the aerosol reflectance as a function of AOD. Results indicate that AOD can be estimated at the local scale from high resolution MODIS data, and the obtained accuracy (ca. 87%) is very much comparable with the accuracy obtained from other studies (80%-95%) for AOD estimation

  19. The 2006 lava dome eruption of Merapi Volcano (Indonesia): Detailed analysis using MODIS TIR

    Science.gov (United States)

    Carr, Brett B.; Clarke, Amanda B.; Vanderkluysen, Loÿc

    2016-02-01

    Merapi is one of Indonesia's most active and dangerous volcanoes. Prior to the 2010 VEI 4 eruption, activity at Merapi during the 20th century was characterized by the growth and collapse of a series of lava domes. Periods of very slow growth were punctuated by short episodes of increased eruption rates characterized by dome collapse-generated pyroclastic density currents (PDCs). An eruptive event of this type occurred in May-June, 2006. For effusive eruptions such as this, detailed extrusion rate records are important for understanding the processes driving the eruption and the hazards presented by the eruption. We use thermal infrared (TIR) images from the Moderate Resolution Imaging Spectrometer (MODIS) instrument on NASA's Aqua and Terra satellites to estimate extrusion rates at Merapi Volcano during the 2006 eruption using the method of Harris and Ripepe (2007). We compile a set of 75 nighttime MODIS images of the eruptive period to produce a detailed time series of thermal radiance and extrusion rate that reveal multiple phases of the 2006 eruption. These data closely correspond to the published ground-based observational record and improve observation density and detail during the eruption sequence. Furthermore, additional analysis of radiance values for thermal anomalies in Band 21 (λ = 3.959 μm) of MODIS images results in a new framework for detecting different styles of activity. We successfully discriminate among slow dome growth, rapid dome growth, and PDC-producing dome collapse. We also demonstrate a positive correlation between PDC frequency and extrusion rate, and provide evidence that extrusion rate can increase in response to external events such as dome collapses or tectonic earthquakes. This study represents a new method of documenting volcanic activity that can be applied to other similar volcanic systems.

  20. Monitoring ice break-up on the Mackenzie River using MODIS data

    Directory of Open Access Journals (Sweden)

    P. Muhammad

    2015-05-01

    Full Text Available This study involves the analysis of Moderate Resolution Imaging Spectroradiometer (MODIS Level 3 500 m snow products (MOD/MYD10A1, complemented with 250 m Level 1B data (MOD/MYD02QKM, to monitor ice cover during the break-up period on the Mackenzie River, Canada. Results from the analysis of data for 13 ice seasons (2001–2013 show that first day ice-off dates are observed between days of year (DOY 115–125 and end DOY 145–155, resulting in average melt durations of about 30–40 days. Floating ice transported northbound could therefore generate multiple periods of ice-on and ice-off observations at the same geographic location. During the ice break-up period, ice melt was initiated by in situ (thermodynamic melt over the drainage basin especially between 61–61.8° N (75–300 km. However, ice break-up process north of 61.8° N was more dynamically driven. Furthermore, years with earlier initiation of the ice break-up period correlated with above normal air temperatures and precipitation, whereas later ice break-up period was correlated with below normal precipitation and air temperatures. MODIS observations revealed that ice runs were largely influenced by channel morphology (islands and bars, confluences and channel constriction. It is concluded that the numerous MODIS daily overpasses possible with the Terra and Aqua polar orbiting satellites, provide a powerful means for monitoring ice break-up processes at multiple geographical locations simultaneously along the Mackenzie River.

  1. Daily MODIS data trends of hurricane-induced forest impact and early recovery

    Science.gov (United States)

    Ramsey, Elijah W., III; Spruce, Joseph; Rangoonwala, Amina; Suzuoki, Yukihiro; Smoot, James; Gasser, Jerry; Bannister, Terri

    2011-01-01

    We studied the use of daily satellite data from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensors to assess wetland forest damage and recovery from Hurricane Katrina (29 August 2005 landfall). Processed MODIS daily vegetation index (VI) trends were consistent with previously determined impact and recovery patterns provided by the "snapshot" 25 m Landsat Thematic Mapper optical and RADARSAT-1 synthetic aperture radar satellite data. Phenological trends showed high 2004 and 2005 pre-hurricane temporal correspondence within bottomland hardwood forest communities, except during spring green-up, and temporal dissimilarity between these hardwoods and nearby cypress-tupelo swamp forests (Taxodium distichum [baldcypress] and Nyssa aquatica [water tupelo]). MODIS VI trend analyses established that one year after impact, cypress-tupelo and lightly impacted hardwood forests had recovered to near pre-hurricane conditions. In contrast, canopy recovery lagged in the moderately and severely damaged hardwood forests, possibly reflecting regeneration of pre-hurricane species and stand-level replacement by invasive trees.

  2. Characterization of beta cell and incretin function in patients with MODY1 (HNF4A MODY) and MODY3 (HNF1A MODY) in a Swedish patient collection

    DEFF Research Database (Denmark)

    Ekholm, E; Shaat, N; Holst, Jens Juul

    2012-01-01

    The aim of this study was to evaluate the beta cell and incretin function in patients with HNF4A and HNF1A MODY during a test meal. Clinical characteristics and biochemical data (glucose, proinsulin, insulin, C-peptide, GLP-1 and GIP) during a test meal were compared between MODY patients from.......8, T2D: 556.4 ± 698.2, HNF4A MODY: 1,257.0 ± 999.3, HNF1A MODY: 697.1 ± 818.4) but with a different secretion pattern. The AUC insulin during the test meal was strongly correlated with the GIP secretion (Correlation coefficient 1.0, P

  3. catena-Poly[[di-μ-aqua-bis[aquacobalt(II

    Directory of Open Access Journals (Sweden)

    2009-03-01

    Full Text Available The title compound, [Co2(C9H4N2O42(H2O4]n, is a one-dimensional polymeric complex with bridging 1H-benzimidazole-5,6-dicarboxylate and aqua ligands. The CoII cation has an octahedral coordination environment provided by an NO5 donor set. Adjacent polymeric chains extended along the [100] direction are linked by O—H...O and N—H...O hydrogen bonds, generating a three-dimensional network.

  4. Cross-Calibration of Earth Observing System Terra Satellite Sensors MODIS and ASTER

    Science.gov (United States)

    McCorkel, J.

    2014-01-01

    The Advanced Spaceborne Thermal Emissive and Reflection Radiometer (ASTER) and Moderate Resolution Imaging Spectrometer (MODIS) are two of the five sensors onboard the Earth Observing System's Terra satellite. These sensors share many similar spectral channels while having much different spatial and operational parameters. ASTER is a tasked sensor and sometimes referred to a zoom camera of the MODIS that collects a full-earth image every one to two days. It is important that these sensors have a consistent characterization and calibration for continued development and use of their data products. This work uses a variety of test sites to retrieve and validate intercalibration results. The refined calibration of Collection 6 of the Terra MODIS data set is leveraged to provide the up-to-date reference for trending and validation of ASTER. Special attention is given to spatially matching radiance measurements using prelaunch spatial response characterization of MODIS. Despite differences in spectral band properties and spatial scales, ASTER-MODIS is an ideal case for intercomparison since the sensors have nearly identical views and acquisitions times and therefore can be used as a baseline of intercalibration performance of other satellite sensor pairs.

  5. Global monitoring of atmospheric properties by the EOS MODIS. Semiannual technical report, January-June 1993

    Energy Technology Data Exchange (ETDEWEB)

    King, M.D.

    1993-01-01

    The Moderate Resolution Imaging Spectroradiometer (MODIS) being developed for the Earth Observing System (EOS) is well suited to the global monitoring of atmospheric properties from space. Among the atmospheric properties to be examined using MODIS observations, clouds are especially important, since they are a strong modulator of the shortwave and longwave components of the earth's radiation budget. A knowledge of cloud properties (such as optical thickness and effective radius) and their variation in space and time, is also crucial to studies of global climate change. In addition, with the use of related airborne instrumentation, such as the Cloud Absorption Radiometer (CAR) and MODIS Airborne Simulator (MAS) in intensive field experiments, various types of surface and cloud properties can be derived from the measured bidirectional reflectances. These missions have provided valuable experimental data to determine the capability of narrow bandpass channels in examining the Earth's atmosphere and to aid in defining algorithms and building an understanding of the ability of MODIS to remotely sense atmospheric conditions for assessing global change. Therefore, the primary task objective is to extend and expand the algorithm for retrieving the optical thickness and effective radius of clouds from radiation measurements to be obtained from MODIS. The secondary objective is to obtain an enhanced knowledge of surface angular and spectral properties that can be inferred from airborne directional radiance measurements.

  6. Mapping paddy rice with multi-date moderate-resolution imaging spectroradiometer (MODIS) data in China

    Institute of Scientific and Technical Information of China (English)

    Hua-sheng SUN; Jing-feng HUANG; Alfredo R. HUETE; Dai-liang PENG; Feng ZHANG

    2009-01-01

    The objective of this study was to obtain spatial distribution maps of paddy rice fields using multi-date moderate-resolution imaging spectroradiometer (MODIS) data in China. Paddy rice fields were extracted by identifying the unique characteristic of high soil moisture in the flooding and transplanting period with improved algorithms based on rice growth calendar regionalization. The characteristic could be reflected by the enhanced vegetation index (EVI) and the land surface water index (LSWI) derived from MODIS sensor data. Algorithms for single, early, and late rice identification were obtained from selected typical test sites. The algorithms could not only separate early rice and late rice planted in the same fields, but also reduce the uncertainties. The areal accuracy of the MODIS-derived results was validated by comparison with agricultural statistics, and the spatial matching was examined by ETM+ (enhanced thematic mapper plus) images in a test region. Major factors that might cause errors, such as the coarse spatial resolution and noises in the MODIS data, were discussed. Although not suitable for monitoring the inter-annual variations due to some inevitable factors, the MODIS-derived results were useful for obtaining spatial distribution maps of paddy rice on a large scale, and they might provide reference for further studies.

  7. Discharge forecasting using MODIS and radar altimetry: potential application for transboundary flood risk management in Niger-Benue River basin

    Science.gov (United States)

    Tarpanelli, Angelica; Amarnath, Giriraj; Brocca, Luca; Moramarco, Tommaso

    2016-04-01

    Flooding is one of most widespread natural disasters in the world. Its impact is particularly severe and destructive in Asia and Africa, because the living conditions of some settlements are inadequate to cope with this type of natural hazard. In this context, the estimation of discharge is extremely important to address water management and flood risk assessment. However, the inadequate monitoring network hampers any control and prediction activity that could improve these disastrous situations. In the last few years, remote sensing sensors have demonstrated their effectiveness in retrieving river discharge, especially in supporting discharge nowcasting and forecasting activities. Recently, the potential of radar altimetry was apparent when used for estimating water levels in an ungauged river site with good accuracy. It has also become a very useful tool for estimation and prediction of river discharge. However, the low temporal resolution of radar altimeter observations (10 or 35 days, depending on the satellite mission) may be not suitable for day-by-day hydrological forecasting. Differently, MODerate resolution Imaging Spectroradiometer (MODIS), considering its proven potential for quantifying the variations in discharge of the rivers at daily time resolution may be more suited to this end. For these reasons, MODIS and radar altimetry data were used in this study to predicting and forecasting the river discharge along the Niger-Benue River, where severe flooding with extensive damage to property and loss of lives occurred. Therefore, an effective method to forecast flooding can support efforts towards creating an early warning system. In order to estimate river discharge, four MODIS products (daily, 8-day, and from AQUA and TERRA satellites) connected at three sites (two gauged and one ungauged) were used. The capability of remote sensing sensors to forecast discharge a few days in advance at a downstream section using MODIS and ENVISAT radar altimetry data

  8. MODIS: an audio motif discovery software

    OpenAIRE

    Catanese, Laurence; Souviraà-Labastie, Nathan; Qu, Bingqing; Campion, Sébastien; Gravier, Guillaume; Vincent, Emmanuel; Bimbot, Frédéric

    2013-01-01

    International audience MODIS is a free speech and audio motif discovery software developed at IRISA Rennes. Motif discovery is the task of discovering and collecting occurrences of repeating patterns in the absence of prior knowledge, or training material. MODIS is based on a generic approach to mine repeating audio sequences, with tolerance to motif variability. The algorithm implementation allows to process large audio streams at a reasonable speed where motif discovery often requires hu...

  9. Impact of MODIS SWIR band calibration improvements on Level-3 atmospheric products

    Science.gov (United States)

    Wald, Andrew; Levy, Robert C.; Angal, Amit; Geng, Xu; Xiong, Jack; Hoffman, Kurt

    2016-05-01

    The spectral reflectance measured by the MODIS reflective solar bands (RSB) is used for retrieving many atmospheric science products. The accuracy of these products depends on the accuracy of the calibration of the RSB. To this end, the RSB of the MODIS instruments are primarily calibrated on-orbit using regular solar diffuser (SD) observations. For λ earth-scene targets. This correction has been implemented in C6 for the Terra MODIS 1.24 μm band over the entire mission, and for the 1.38 μm band in the forward processing. As the instruments continue to operate beyond their design lifetime of six years, a similar correction is planned for other short-wave infrared (SWIR) bands as well. MODIS SWIR bands are used in deriving atmosphere products, including aerosol optical thickness, atmospheric total column water vapor, cloud fraction and cloud optical depth. The SD degradation correction in Terra bands 5 and 26 impact the spectral radiance and therefore the retrieval of these atmosphere products. Here, we describe the corrections to Bands 5 (1.24 μm) and 26 (1.38 μm), and produce three sets (B5, B26 correction = on/on, on/off, and off/off) of Terra-MODIS Level 1B (calibrated radiance product) data. By comparing products derived from these corrected and uncorrected Terra MODIS Level 1B (L1B) calibrations, dozens of L3 atmosphere products are surveyed for changes caused by the corrections, and representative results are presented. Aerosol and water vapor products show only small local changes, while some cloud products can change locally by >10%, which is a large change.

  10. Structural and Functional Characterization of a Novel Family of Cyclophilins, the AquaCyps.

    Science.gov (United States)

    Jakob, Roman P; Schmidpeter, Philipp A M; Koch, Johanna R; Schmid, Franz X; Maier, Timm

    2016-01-01

    Cyclophilins are ubiquitous cis-trans-prolyl isomerases (PPIases) found in all kingdoms of life. Here, we identify a novel family of cyclophilins, termed AquaCyps, which specifically occurs in marine Alphaproteobacteria, but not in related terrestric species. In addition to a canonical PPIase domain, AquaCyps contain large extensions and insertions. The crystal structures of two representatives from Hirschia baltica, AquaCyp293 and AquaCyp300, reveal the formation of a compact domain, the NIC domain, by the N- and C-terminal extensions together with a central insertion. The NIC domain adopts a novel mixed alpha-helical, beta-sheet fold that is linked to the cyclophilin domain via a conserved disulfide bond. In its overall fold, AquaCyp293 resembles AquaCyp300, but the two proteins utilize distinct sets of active site residues, consistent with differences in their PPIase catalytic properties. While AquaCyp293 is a highly active general PPIase, AquaCyp300 is specific for hydrophobic substrate peptides and exhibits lower overall activity. PMID:27276069

  11. Structural and Functional Characterization of a Novel Family of Cyclophilins, the AquaCyps.

    Directory of Open Access Journals (Sweden)

    Roman P Jakob

    Full Text Available Cyclophilins are ubiquitous cis-trans-prolyl isomerases (PPIases found in all kingdoms of life. Here, we identify a novel family of cyclophilins, termed AquaCyps, which specifically occurs in marine Alphaproteobacteria, but not in related terrestric species. In addition to a canonical PPIase domain, AquaCyps contain large extensions and insertions. The crystal structures of two representatives from Hirschia baltica, AquaCyp293 and AquaCyp300, reveal the formation of a compact domain, the NIC domain, by the N- and C-terminal extensions together with a central insertion. The NIC domain adopts a novel mixed alpha-helical, beta-sheet fold that is linked to the cyclophilin domain via a conserved disulfide bond. In its overall fold, AquaCyp293 resembles AquaCyp300, but the two proteins utilize distinct sets of active site residues, consistent with differences in their PPIase catalytic properties. While AquaCyp293 is a highly active general PPIase, AquaCyp300 is specific for hydrophobic substrate peptides and exhibits lower overall activity.

  12. An unprecedented tetranuclear niobium aqua ion with a capping μ4-sulfido ligand

    DEFF Research Database (Denmark)

    Ooi, Bee Lean; Søtofte, Inger

    2005-01-01

    A new niobium aqua ion, with an unprecedented metal-metal bonded tetranuclear Nb4(μ4-S)(μ2-O)54+ core, is obtained upon treatment of Zn-reduced ethanolic solutions of NbCl5 with HCl in the presence of a sulfide source. The red aqua ion, obtained upon cation-exchange chromatography, forms readily...

  13. Structural and Functional Characterization of a Novel Family of Cyclophilins, the AquaCyps

    Science.gov (United States)

    Jakob, Roman P.; Schmidpeter, Philipp A. M.; Koch, Johanna R.; Schmid, Franz X.; Maier, Timm

    2016-01-01

    Cyclophilins are ubiquitous cis-trans-prolyl isomerases (PPIases) found in all kingdoms of life. Here, we identify a novel family of cyclophilins, termed AquaCyps, which specifically occurs in marine Alphaproteobacteria, but not in related terrestric species. In addition to a canonical PPIase domain, AquaCyps contain large extensions and insertions. The crystal structures of two representatives from Hirschia baltica, AquaCyp293 and AquaCyp300, reveal the formation of a compact domain, the NIC domain, by the N- and C-terminal extensions together with a central insertion. The NIC domain adopts a novel mixed alpha-helical, beta-sheet fold that is linked to the cyclophilin domain via a conserved disulfide bond. In its overall fold, AquaCyp293 resembles AquaCyp300, but the two proteins utilize distinct sets of active site residues, consistent with differences in their PPIase catalytic properties. While AquaCyp293 is a highly active general PPIase, AquaCyp300 is specific for hydrophobic substrate peptides and exhibits lower overall activity. PMID:27276069

  14. Enhancement of the MODIS Daily Snow Albedo Product

    Science.gov (United States)

    Hall, Dorothy K.; Schaaf, Crystal B.; Wang, Zhuosen; Riggs, George A.

    2009-01-01

    The MODIS daily snow albedo product is a data layer in the MOD10A1 snow-cover product that includes snow-covered area and fractional snow cover as well as quality information and other metadata. It was developed to augment the MODIS BRDF/Albedo algorithm (MCD43) that provides 16-day maps of albedo globally at 500-m resolution. But many modelers require daily snow albedo, especially during the snowmelt season when the snow albedo is changing rapidly. Many models have an unrealistic snow albedo feedback in both estimated albedo and change in albedo over the seasonal cycle context, Rapid changes in snow cover extent or brightness challenge the MCD43 algorithm; over a 16-day period, MCD43 determines whether the majority of clear observations was snow-covered or snow-free then only calculates albedo for the majority condition. Thus changes in snow albedo and snow cover are not portrayed accurately during times of rapid change, therefore the current MCD43 product is not ideal for snow work. The MODIS daily snow albedo from the MOD10 product provides more frequent, though less robust maps for pixels defined as "snow" by the MODIS snow-cover algorithm. Though useful, the daily snow albedo product can be improved using a daily version of the MCD43 product as described in this paper. There are important limitations to the MOD10A1 daily snow albedo product, some of which can be mitigated. Utilizing the appropriate per-pixel Bidirectional Reflectance Distribution Functions (BRDFs) can be problematic, and correction for anisotropic scattering must be included. The BRDF describes how the reflectance varies with view and illumination geometry. Also, narrow-to-broadband conversion specific for snow on different surfaces must be calculated and this can be difficult. In consideration of these limitations of MOD10A1, we are planning to improve the daily snow albedo algorithm by coupling the periodic per-pixel snow albedo from MCD43, with daily surface ref|outanoom, In this paper, we

  15. Operational Experiences in Planning and Reconstructing Aqua Inclination Maneuvers

    Science.gov (United States)

    Rand, David; Reilly, Jacqueline; Schiff, Conrad

    2004-01-01

    As the lead satellite in NASA's growing Earth Observing System (EOS) PM constellation, it is increasingly critical that Aqua maintain its various orbit requirements. The two of interest for this paper are maintaining an orbit inclination that provides for a consistent mean local time and a semi-major Axis (SMA) that allows for ground track repeatability. Maneuvers to adjust the orbit inclination involve several flight dynamics constraints and complexities which make planning such maneuvers challenging. In particular, coupling between the orbital and attitude degrees of freedom lead to changes in SMA when changes in inclination are effected. A long term mission mean local time trend analysis was performed in order to determine the size and placement of the required inclination maneuvers. Following this analysis, detailed modeling of each burn and its Various segments was performed to determine its effects on the immediate orbit state. Data gathered from an inclination slew test of the spacecraft and first inclination maneuver uncovered discrepancies in the modeling method that were investigated and resolved. The new modeling techniques were applied and validated during the second spacecraft inclination maneuver. These improvements should position Aqua to successfully complete a series of inclination maneuvers in the fall of 2004. The following paper presents the events and results related

  16. A Study on the Effects of Bee Venom Aqua-Acupuncture on Writhing Reflex

    Directory of Open Access Journals (Sweden)

    Jeong Sun-Hee

    2000-07-01

    Full Text Available Introduction:In spite of the use of Bee Venom aqua-acupuncture in the clinics, the scientific evaluation on effects is not enough. Bee Venom aqua-acupuncture is used according to the stimulation of acupuncture point and the chemical effects of Bee Venom. The aims of this study is to investigate the analgegic effects of the Bee Venom aqua-acupuncture, through the change of writhing reflex Materials and Methods:Pain animal model was used acetic acid method. The changes of writhing reflex of the mice which were derived pain by injecting acetic acid into the abdomen, after stimulating Bee Venom aqua-acupuncture on Chungwan(CV12 and non acupuncture point on the backside were measured. Results:1. It showed that the writhing reflex were appeared on the groups which injected acetic acid only, and saline-acetic acid group(sample I, but not on the group bee venom-saline group(sample II. 2. The change of writhing reflex by Chungwan(CV12 Bee Venom aqua-acupuncture showed significant decrease in the order of Chungwan(CV12 Bee Venom aqua-acupuncture group III(2.5×10-3g/kg, II(2.5×10-4g/kg, and I(2.5×10-5g/kg, compared with control group. There were significant decrease of number of writhing reflex in 5~10, 10~15 and 15~20 minutes intervals of Chung wan(CV12 Bee Venom aqua-acupuncture group I, and in 0~5, 5~10, 10~15 and 15~20 minutes intervals of II and III, compared with control group. 3. The change of writhing reflex by non acupuncture point Bee Venom aqua-acupuncture showed significant decrease in the 0~5 and 5~10 minutes intervals and the total number of writhing reflex in 2.5×10-4g/kg group, compared with control group 4. The effects of writhing reflex of Chungwan(CV12 Bee Venom aqua-acupuncture group showed significant decrease, compared with non acupuncture point Bee Venom aqua-acupuncture group. Conclusion:This study shows that the Bee Venom aqua-acupuncture on Chungwan(CV12 decreases the numbers of writhing reflex. As the

  17. Validation of MODIS aerosol products by CSHNET over China

    Institute of Scientific and Technical Information of China (English)

    WANG LiLi; XIN JinYuan; WANG YueSi; LI ZhanQing; WANG PuCai; LIU GuangRen; WEN TianXue

    2007-01-01

    The Chinese Sun Hazemeter Network(CSHNET)provides the necessary ground-based observation to validate and assess the applicability of MODIS aerosol optical depth(AOD)products over different ecological and geographic regions in China for the first time.The validation results show that the comprehensive utilization ratio and applicability of MODIS products varied very much over different regions and seasons from August 2004 to July 2005.On the Tibetan Plateau,the comprehensive utilization ratio of MODIS data was low:MODIS products only accounted for 16% of the ground-based observation;on average,31% to 45% of MODIS products fell within the retrieval errors issued by NASA.A similar result was found in northern desert areas with the ratio of MODIS to observation ranging from 15% to 55%,with 7% to 39% of MODIS products within errors.In the remote northeast corner of China,low ratios of MODIS to observation were also found ranging from 14% to 46%,with 49% to 69% of MODIS within errors.The forested sites exhibited moderate ratios of MODIS to observation ranging from 46% to 65%,with 30% to 59% of MODIS within errors.This was similar to numbers observed at sites along eastern seashore of China and inland urban sites with the ratio of MODIS to observation between 63% to 75%,with 25% to 67% of MODIS within errors for sites along eastern seashore of China and 43% to 78%,with 35% to 75% of MODIS within errors for inland urban sites.The ratio of MODIS to observation over agricultural areas ranged from 61% to 89%;59%-88% of MODIS fell within the retrieval errors.At homogeneous and well vegetated areas,the comprehensive utilization ratio of MODIS products was over 80% and above 70% of MODIS products fell within the retrieval errors in growing Season.

  18. Impact of MODIS SWIR band calibration improvements on Level-3 atmospheric products

    Science.gov (United States)

    Wald, Andrew; Levy, Robert C.; Angal, Amit; Geng, Xu; Xiong, Jack; Hoffman, Kurt

    2016-05-01

    The spectral reflectance measured by the MODIS reflective solar bands (RSB) is used for retrieving many atmospheric science products. The accuracy of these products depends on the accuracy of the calibration of the RSB. To this end, the RSB of the MODIS instruments are primarily calibrated on-orbit using regular solar diffuser (SD) observations. For λ vapor, cloud fraction and cloud optical depth. The SD degradation correction in Terra bands 5 and 26 impact the spectral radiance and therefore the retrieval of these atmosphere products. Here, we describe the corrections to Bands 5 (1.24 μm) and 26 (1.38 μm), and produce three sets (B5, B26 correction = on/on, on/off, and off/off) of Terra-MODIS Level 1B (calibrated radiance product) data. By comparing products derived from these corrected and uncorrected Terra MODIS Level 1B (L1B) calibrations, dozens of L3 atmosphere products are surveyed for changes caused by the corrections, and representative results are presented. Aerosol and water vapor products show only small local changes, while some cloud products can change locally by >10%, which is a large change.

  19. Estimating Freshwater Discharge from the Greenland Ice Sheet with MODIS

    Science.gov (United States)

    Hudson, B. D.; Overeem, I.; Mikkelsen, A. B.; McGrath, D.; Syvitski, J. P.

    2013-12-01

    Freshwater discharge from the Greenland Ice Sheet (GrIS) has significant ecological importance, impacts ocean circulation and represents a major contribution to global sea level rise. Despite these factors, only one river in Greenland (accounting for less than one percent of land terminating river outlets) has a published discharge record. Due to logistical constrains future efforts to directly gauge river discharge will likely remain ad hoc. To overcome this deficiency, we developed a remote sensing technique that utilizes observations of sediment plume geometry as a proxy for freshwater discharge from the ice sheet. We use MODIS (Moderate Resolution Imaging Spectroradiometer) imagery, validated with a suite of oceanographic measurements from four fjords in southwest Greenland during the 2008, 2010, 2011 and 2012 summer seasons. From surface water samples collected during these campaigns we develop a robust retrieval algorithm for suspended sediment concentrations based on MODIS band one and two reflectance values (r2 =.84). This relationship allows us to accurately map sediment plume geometry of numerous river-fjord systems on all cloud-free days during the summer season. We then use in situ river discharge records from the Watson River at Kangerlussuaq (a six year record), ';Pakitsuup South' River near Illulisat (a two year record) and Naujat Kuat River near Nuuk (a three year record) to derive an empirical relationship between plume geometry and discharge volume. These fjords provide a robust test for this method, as fjord salinity for these locations span a continuum of river-dominated low salinity to ocean-dominated high salinity cases. We find high interannual stability in these relationships for individual sites, suggesting that this method may be suitable for estimating historical river discharges back to 2000 when Terra, the first satellite carrying MODIS was launched. Despite promise, variability in the empirical relationships found precludes

  20. Reconstruction of MODIS daily land surface temperature under clouds

    Science.gov (United States)

    Sun, L.; Gao, F.; Chen, Z.; Song, L.; Xie, D.

    2015-12-01

    Land surface temperature (LST), generally defined as the skin temperature of the Earth's surface, controls the process of evapotranspiration, surface energy balance, soil moisture change and climate change. Moderate Resolution Imaging Spectrometer (MODIS) is equipped with 1km resolution thermal sensor andcapable of observing the earth surface at least once per day.Thermal infrared bands cannot penetrate cloud, which means we cannot get consistency drought monitoring condition at one area. However, the cloudy-sky conditions represent more than half of the actual day-to-day weather around the global. In this study, we developed an LST filled model based on the assumption that under good weather condition, LST difference between two nearby pixels are similar among the closest 8 days. We used all the valid pixels covered by a 9*9 window to reconstruct the gap LST. Each valid pixel is assigned a weight which is determined by the spatial distance and the spectral similarity. This model is applied in the Middle-East of China including Gansu, Ningxia, Shaanxi province. The terrain is complicated in this area including plain and hill. The MODIS daily LST product (MOD11A3) from 2000 to 2004 is tested. Almost all the gap pixels are filled, and the terrain information is reconstructed well and smoothly. We masked two areas in order to validate the model, one located in the plain, another located in the hill. The correlation coefficient is greater than 0.8, even up to 0.92 in a few days. We also used ground measured day maximum and mean surface temperature to valid our model. Although both the temporal and spatial scale are different between ground measured temperature and MODIS LST, they agreed well in all the stations. This LST filled model is operational because it only needs LST and reflectance, and does not need other auxiliary information such as climate factors. We will apply this model to more regions in the future.