WorldWideScience

Sample records for aqua modis reflectance

  1. 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...

  2. 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...

  3. 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...

  4. 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.

  5. 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...

  6. 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...

  7. 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...

  8. 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...

  9. 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...

  10. 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...

  11. 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...

  12. 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...

  13. 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.

  14. Status of time-dependent response versus scan-angle (RVS) for Terra and Aqua MODIS reflective solar bands

    Science.gov (United States)

    Geng, Xu; Angal, Amit; Sun, Junqiang; Chen, Hongda; Wu, Aisheng; Li, Yonghong; Link, Daniel; Xiong, Xiaoxiong

    2014-09-01

    The MODerate resolution Imaging Spectroradiometer (MODIS) has 20 reflective solar bands (RSB), which are calibrated using a solar diffuser (SD) and near-monthly scheduled lunar observations via a space view (SV) port. The sensor responses observed at two different angles of incidence (AOI) from the SD and lunar measurements are used to track the on-orbit RSB gain changes as well as the response versus scan-angle (RVS) changes. The MODIS RSB have experienced wavelength dependent degradation since launch with the larger degradation observed at the shorter wavelengths. In addition to the SD and lunar observations, the MODIS Characterization Support Team (MCST) regularly monitors the response trending at multiple AOI over selected desert sites. In Collection 6 (C6), a new algorithm using the EV measurements from pseudoinvariant desert sites was developed to better characterize the MODIS scan-angle dependence and it led to a significant improvement in the long-term calibration consistency of the MODIS Level 1B (L1B) products. This approach is formulated for all RSB, and its application was recently extended to Terra band 10, leading to a significant improvement in the ocean-color products. This paper discusses the current status and performance of the on-orbit RVS characterization as applied in C6. Also, the various challenges and future improvement strategies associated with trending the EV response for the high-gain ocean bands are discussed.

  15. 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.

  16. 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...

  17. 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.

  18. 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.

  19. 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...

  20. 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.

  1. 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.

  2. 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; HU Yincui

    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.

  3. 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.

  4. 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...

  5. 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...

  6. 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

  7. 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

    simple 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...... barley, wheat, and deciduous forest sites, respectively. Despite the independence on site-specific in-situ measurements, the RMS deviations of the automated approach are in the same range as those established in other studies employing field-based empirical calibration. Being completely automated and...

  8. 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...

  9. 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 ...

  10. 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...

  11. 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...

  12. 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...

  13. 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...

  14. 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...

  15. 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...

  16. 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

  17. 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...

  18. 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...

  19. 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...

  20. 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

  1. 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

    Solar irradiance is a key environmental control, and accurate spatial and temporal solar irradiance data are important for a wide range of applications related to energy and carbon cycling, weather prediction, and climate change. This study presents a satellite-based scheme for the retrieval of all...... the Terra and Aqua satellites, and employs a cloud motion tracking scheme for the production of hourly solar irradiance data throughout the day. The scheme was implemented for the Island of Zealand, Denmark (56° N, 12° E) and Southern Arizona, USA (31° N, 110° W) permitting model evaluation for two highly...... 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...

  2. 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

  3. 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

  4. 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...

  5. MODIS reflective solar bands calibration improvements in Collection 6

    Science.gov (United States)

    Sun, Junqiang; Angal, Amit; Xiong, Xiaoxiong; Chen, Hongda; Geng, Xu; Wu, Aisheng; Choi, Taeyoung; Chu, Mike

    2012-11-01

    Since launch, Terra and Aqua MODIS have performed more than 12 and 10 years of scientific measurements of the Earth's surface. MODIS has 36 spectral bands, among which 20 are Reflective Solar Bands (RSB), covering a spectral range from 0.41 μm to 2.1 μm. MODIS was developed with stringent requirements for calibration and uncertainty and is equipped with a set of on-board calibrators (OBC) that facilitate a constant monitoring and update of its on-orbit calibration coefficients. The RSB are calibrated on-orbit using a Solar Diffuser (SD) and a Solar Diffuser Stability Monitor (SDSM), with help from the lunar observations via a Space View (SV) port and an onboard Spectroradiometric Calibration Assembly (SRCA). The algorithms to accurately characterize the sensor's gain change and the on-orbit change in the response versus scan-angle (RVS) have been applied to improve the quality of the Earth-view measurements. Various improvements to the calibration algorithms have been incorporated since launch and the following paper will discuss the calibration algorithms and enhancements developed for MODIS Collection 6 (C6) processing. In addition, to supplement the measurements from the on-board calibrators, pseudo-invariant desert targets are also used to track the on-orbit response change for selective RSB. Discussions of the on-orbit calibration uncertainty and the Level 1B (L1B) Uncertainty index (UI) product are also included. A comprehensive assessment of the impact on the L1B product in comparison to Collection 5 (C5) is also discussed. Significant improvements are observed in the case of VIS bands wherein the long-term bias observed in C5 products is eliminated to provide a more accurate radiometric product.

  6. 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)

  7. 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.

  8. MODIS/Aqua 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....

  9. 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....

  10. 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

    . Our results show that for the geographical, atmospheric and optical conditions of Lake Tanganyika: (i) a coastal aerosol model set with high relative humidity (90%) provides a suitable atmospheric correction; (ii) a significant correlation between in situ data and CHL estimates using the MODIS......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 is a...... 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...

  11. Characterization of MODIS mirror side difference in the reflective solar spectral region

    Science.gov (United States)

    Geng, X.; Angal, A.; Sun, J.; Wu, A.; Choi, T.; Xiong, X.

    2011-10-01

    The MODIS instruments onboard the Terra and Aqua spacecraft, launched in December 1999 and May 2002, respectively, have successfully operated through the present time. MODIS collects the Earth view (EV) data via a twosided paddle wheel scan mirror at angles of incidence (AOI) from 10.5 to 65.5 degrees. Reflective properties between the two mirror sides are not identical with large differences seen in Terra MODIS reflective solar bands (RSB). This paper describes a methodology to calculate and monitor MODIS RSB mirror side differences using EV observations. The longterm trends of response differences between two mirror sides are evaluated using different EV targets. Results show that the on-orbit changes in the properties of the scan mirror are wavelength and AOI dependent with large mirror side differences observed at shorter wavelengths in larger AOI. Starting from 2005, the mirror side difference has gradually exhibited a seasonally dependent feature in Terra MODIS visible spectral bands, which is mainly due to the changes in the scan mirror polarization property. In addition to fully characterizing on-orbit changes of the MODIS scan mirror properties, results and discussions provided in this paper will help clarify their impacts on the Level 1B data products and support future efforts to maintain MODIS data quality.

  12. 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.

  13. 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...

  14. 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...

  15. 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...

  16. 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...

  17. 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...

  18. Progress on alternative method of the on-orbit RVS characterization for MODIS reflective solar bands

    Science.gov (United States)

    Chen, H.; Xiong, X.; Angal, A.; Geng, X.; Wu, A.

    2014-09-01

    MODIS Reflective Solar Bands (RSB) are calibrated on-orbit using its onboard calibrators, including a Solar Diffuser (SD), a Solar Diffuser Stability Monitor (SDSM), and a Spectroradiometric Calibration Assembly (SRCA). A Space View (SV) port is used to provide a background reference, and also facilitate near monthly lunar observations via a spacecraft roll. In every scan, the earth's surface, SV and onboard calibrators are viewed via a two sided scan mirror, whose reflectance depends on the angles of the 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) response from pseudo-invariant desert targets obtained at different AOI. The current approach, as implemented in Collection 6 (C6), uses EV responses from the Libyan desert sites to track the on-orbit RVS change. It strongly depends on the long-term temporal stability of the desert sites. As an effort to validate and, if necessary, to improve MODIS RSB RVS characterization for future applications, the MODIS Characterization Support Team (MCST) has developed and tested an alternative approach to monitor the on-orbit RVS change, using a response from a single desert site. The purpose of using data from one site is to avoid the impact of possible differences in the long-term temporal stability among multiple sites on the calculation of the on-orbit RVS. This paper updates recent progress in the formulation of the alternative RVS approach. Comprehensive comparisons were also performed with current C6 RVS results for both Terra and Aqua MODIS. Results demonstrate that this alternative method provides a supplemental means to track the on-orbit RVS for MODIS RSB.

  19. 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.

  20. 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

  1. 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.

  2. 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.

  3. 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.

  4. 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

  5. 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...

  6. 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...

  7. 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...

  8. 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.

  9. The regime of aerosol optical depth over Central Asia based on MODIS Aqua Deep Blue data

    Science.gov (United States)

    Floutsi, Athina; KorrasCarraca, Marios; Matsoukas, Christos; Biskos, George

    2015-04-01

    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 therefore important to determine the aerosol load, and an effective way to do that is by measuring the aerosol optical depth (AOD). In this study we investigate the spatial and temporal variability of the AOD over the climatically sensitive region of Central Asia (36° N - 50° N, 46° E - 75° E), which has significant sources of both natural and anthropogenic particles. The primary source of anthropogenic particles is fossil fuel combustion occurring mainly at oil refineries in the Caspian Sea basin. Natural particles originate mostly from the two deserts in the region (namely Kara-Kum and Kyzyl-Kum), where persistent dust activity is observed. Another source is the Aral Sea region, which due to its phenomenal desertification also drives an intense salt and dust transport from the exposed sea-bed to the surrounding regions. This transport is of particular interest because of health-hazardous materials contained in the Aral Sea sea-bed. For our analysis we use Level-3 daily MODIS - Aqua Dark Target - Deep Blue combined product, from the latest MODIS collection (006), available in 1° x 1° resolution (about 100 km x 100 km) over the period 2002-2014.Our first results indicate a significant spatial variability of the aerosol load over the study region. The data also show a clear seasonal cycle, with large aerosol load being associated with strong dust activity during spring and summer (AOD up to 0.5), and low during autumn and winter (AOD up to 0.4). In spring and summer significant aerosol load is observed in the Garabogazköl basin, Northeast and South-southeast Caspian Sea (offshore North Iran and Azerbaijan), as well as southwest of the Aral Sea. In the later region, the high AOD values can be explained by export of

  10. 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...

  11. 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...

  12. 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...

  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. 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...

  15. Diffuse Attenuation Coef. K490, Aqua MODIS, NPP, 0.125 degrees, East US

    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...

  16. 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...

  17. 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

  18. Fluorescence, Aqua MODIS, NPP, 0.125 degrees, Gulf of Mexico

    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. 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...

  20. 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...

  1. 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...

  2. 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...

  3. 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...

  4. 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...

  5. 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...

  6. 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

  7. 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

  8. Comparison of C5 and C6 Aqua-MODIS Dark Target Aerosol Validation

    Science.gov (United States)

    Munchak, Leigh A.; Levy, Robert C.; Mattoo, Shana

    2014-01-01

    We compare C5 and C6 validation to compare the C6 10 km aerosol product against the well validated and trusted aerosol product on global and regional scales. Only the 10 km aerosol product is evaluated in this study, validation of the new C6 3 km aerosol product still needs to be performed. Not all of the time series has processed yet for C5 or C6, and the years processed for the 2 products is not exactly the same (this work is preliminary!). To reduce the impact of outlier observations, MODIS is spatially averaged within 27.5 km of the AERONET site, and AERONET is temporatally averaged within 30 minutes of the MODIS overpass time. Only high quality (QA = 3 over land, QA greater than 0 over ocean) pixels are included in the mean.

  9. 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

  10. 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)...

  11. 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.

  12. 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...

  13. 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...

  14. 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.

  15. 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%.

  16. 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.

  17. 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...

  18. 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...

  19. 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

  20. 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

  1. 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...

  2. 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...

  3. 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...

  4. 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...

  5. 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.

  6. 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.

  7. 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.

  8. 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...

  9. 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...

  10. 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...

  11. 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...

  12. A better understanding of cloud optical thickness derived from the passive sensors MODIS/AQUA and POLDER/PARASOL in the A-train constellation

    Directory of Open Access Journals (Sweden)

    S. Zeng

    2012-05-01

    Full Text Available Cloud optical thickness (COT is one of the most important parameter for the characterization of cloud in the Earth radiative budget. Its retrieval strongly depends on instrument characteristics and on many cloud and environment factors. Using coincident observations from POLDER/PARASOL and MODIS/AQUA in the A-train constellation, geographical distributions and seasonal changes of COT are presented, in good agreement with general cloud climatology characteristics. Retrieval uncertainties mainly associated to sensor spatial resolution, cloud inhomogeneity and microphysical assumptions are also discussed.

    Comparisons of COT derived from POLDER and MODIS illustrate that as the primary factor, the sensor spatial resolution impacts COT retrievals and statistics through both cloud detection and sub-pixel cloud inhomogeneity sensitivity.

    The uncertainties associated to cloud microphysics assumptions, namely cloud phase, particle size and shape, also impact significantly COT retrievals. For clouds with unambiguous cloud phase, strong correlations exist between the two COTs, with MODIS values comparable to POLDER ones for liquid clouds and MODIS values larger than POLDER ones for ice clouds. The large differences observed in ice phase cases are due to the use of different microphysical models in the two retrieval schemes. In cases when the two sensors disagree on cloud phase decision, COT retrieved assuming liquid phase are systematically larger.

    The angular biases related to specific observation geometries are also quantified and discussed in particular based on POLDER observations. Those exhibit a clear increase of COT with decreasing sun elevation and a decrease of COT in forward scattering directions due to sub-pixel inhomogeneities and shadowing effects, this especially for lower sun. It also demonstrates unrealistic COT variations in the rainbow and backward directions due to inappropriate cloud optical properties

  13. A better understanding of cloud optical thickness derived from the passive sensors MODIS/AQUA and POLDER/PARASOL in the A-Train constellation

    Directory of Open Access Journals (Sweden)

    S. Zeng

    2012-12-01

    Full Text Available Cloud optical thickness (COT is one of the most important parameter for the characterization of cloud in the Earth radiative budget. Its retrieval strongly depends on instrument characteristics and on many cloud and environment factors. Using coincident observations from POLDER/PARASOL and MODIS/AQUA in the A-Train constellation, geographical distributions and seasonal changes of COT are presented, in good agreement with general cloud climatology characteristics. Retrieval uncertainties mainly associated to sensor spatial resolution, cloud inhomogeneity and microphysical assumptions are discussed.

    Comparisons of COT derived from POLDER and MODIS illustrate that as the primary factor, the sensor spatial resolution impacts COT retrievals and statistics through both cloud detection and sub-pixel cloud inhomogeneity sensitivity.

    The uncertainties associated to cloud microphysics assumptions, namely cloud phase, particle size and shape, also impact significantly COT retrievals. For clouds with unambiguous cloud phase, strong correlations exist between the two COTs, with MODIS values comparable to POLDER ones for liquid clouds and MODIS values larger than POLDER ones for ice clouds. The large differences observed in ice phase cases are due to the use of different microphysical models in the two retrieval schemes. In cases when the two sensors disagree on cloud phase decision, COT retrieved assuming liquid phase is systematically larger.

    The angular biases related to specific observation geometries are also quantified and discussed in particular based on POLDER observations. Those exhibit a clear increase of COT with decreasing sun elevation and a decrease of COT in forward scattering directions due to sub-pixel inhomogeneities and shadowing effects, this especially for lower sun. It also demonstrates unrealistic COT variations in the cloudbow and backward directions due to inappropriate cloud optical properties

  14. 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...

  15. 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...

  16. 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...

  17. 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...

  18. MODIS/Aqua 8-Day Clear Sky Radiance Bias Daily L3 Global 1Deg Zonal Bands V005

    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...

  19. 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...

  20. 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...

  1. 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...

  2. 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...

  3. 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...

  4. 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.

  5. 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

  6. 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...

  7. 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.

  8. 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

    A modified version of the MODerate resolution Imaging Spectroradiometer (MODIS) bidirectional reflectance distribution function (BRDF) algorithm is presented for use in the angular normalization of surface reflectance data gathered by the Spinning Enhanced Visible and InfraRed Imager (SEVIRI...... acquisition period than the comparable MODIS products while, at the same time, removing many of the angular perturbations present within the original MSG data. The NBAR data are validated against reflectance data from the MODIS instrument and in situ data gathered at a field location in Africa throughout 2008....... 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...

  9. On-orbit aqua MODIS modulation transfer function trending in along-scan from the Spectro-Radiometric Calibration Assembly

    Science.gov (United States)

    Choi, Taeyoung; Che, Nianzeng; Xiong, Xiaoxiong

    2008-08-01

    The Spectro-Radiometric Calibration Assembly (SRCA) is one of the on-board calibrators for the MODIS instrument. The SRCA is operated in three modes: spectral, spatial, and radiometric. The spatial mode is used to track the changes in band-to-band registration both along-scan (band and detector) and along-track (band) and the MTF in the along-scan direction for all 36 MODIS bands over the MODIS lifetime. In the SRCA spatial mode, a rectangular knife-edge reticle, located at the focus of the SRCA collimator, is imaged onto four MODIS Focal Plane Assemblies (FPA). The reticle is illuminated by a spherical integration sphere and a glow-bar so that all bands can have an appropriate signal level. When the MODIS scan mirror rotates, the illuminated knife-edge scans across the bands/detectors. In addition, there are five electronic phase-delays so that the sampling spacing is reduced to 1/5 of the detector size, which results in dense data points. After combining detector responses from all phase-delays, a combined bell-shaped response profile is formed. The derivative of the detector response to the knife-edge is the Line Spread Function (LSF). In the frequency domain, the Modulation Transfer Functions (MTF) are calculated from the normalized Fourier transform of the LSF. The MTF results from the SRCA are validated by the pre-launch results from the Integrated Alignment Collimator (IAC) and a SRCA collection performed in the Thermal Vacuum (TV). The six-year plus on-orbit MTF trending results show very stable responses in the VIS and NIR FPAs, and meet the design specifications. Although there are noticeable MTF degradations over the instrument lifetime in bands 1 and 2, they are negligible with the large specification margins. In addition, a similar relationship is found between the band locations in the VIS and NIR FPAs versus MTF values.

  10. 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...

  11. Spatial and temporal variability of chlorophyll-a concentrations in the coastal Gulf of Alaska, 1998-2011, using cloud-free reconstructions of SeaWiFS and MODIS-Aqua data

    Science.gov (United States)

    Waite, Jason N.; Mueter, Franz J.

    2013-09-01

    We examined the spatial and temporal variability of chlorophyll-a (chl-a) concentrations in the coastal Gulf of Alaska (GOA) using a 14-year time series of cloud-free reconstructions of SeaWiFS and MODIS-Aqua chl-a data. Coast-wide and regional relationships between chl-a and likely environmental drivers, including anomalies in sea surface temperature (SST), photosynthetically-available radiation (PAR), sea surface height (SSHa), freshwater discharge, and coastal upwelling were explored. Coast-wide chl-a showed strong seasonal variability with pronounced spring and fall blooms, but both the magnitude and the seasonal patterns showed considerable interannual variability. Coast-wide annual chl-a anomalies were positive in years with elevated PAR, low SST, and a reduction in downwelling-favorable winds - conditions that are indicative of reduced cyclonic circulation associated with a weak Aleutian Low. The apparent negative effect of strong cyclonic circulation in the GOA on chl-a levels was further supported by negative relationships between elevated sea levels and coast-wide chl-a in both the spring and fall. If chl-a concentrations in the coastal GOA reflect productivity, these results are contrary to the prevailing view that strong cyclonic circulation enhances productivity in the GOA. The variability in the chl-a in each of four distinct and spatially contiguous regions that differed in the timing and magnitude of the spring and fall blooms was associated with different combinations of environmental variables.

  12. MODIS Radiometric Calibration and Uncertainty Assessment

    Science.gov (United States)

    Xiong, Xiaoxiong; Chiang, Vincent; Sun, Junqiang; Wu, Aisheng

    2011-01-01

    Since launch, Terra and Aqua MODIS have collected more than II and 9 years of datasets for comprehensive studies of the Earth's land, ocean, and atmospheric properties. MODIS observations are made in 36 spectral bands: 20 reflective solar bands (RSB) and 16 thermal emissive bands (TEB). Compared to its heritage sensors, MODIS was developed with very stringent calibration and uncertainty requirements. As a result, MODIS was designed and built with a set of state of the art on-board calibrators (OBC), which allow key sensor performance parameters and on-orbit calibration coefficients to be monitored and updated if necessary. In terms of its calibration traceability, MODIS RSB calibration is reflectance based using an on-board solar diffuser (SD) and the TEB calibration is radiance based using an on-board blackbody (BB). In addition to on-orbit calibration coefficients derived from its OBC, calibration parameters determined from sensor pre-launch calibration and characterization are used in both the RSB and TEB calibration and retrieval algorithms. This paper provides a brief description of MODIS calibration methodologies and discusses details of its on-orbit calibration uncertainties. It assesses uncertainty contributions from individual components and differences between Terra and Aqua MODIS due to their design characteristics and on-orbit periormance. Also discussed in this paper is the use of MODIS LIB uncertainty index CUI) product.

  13. 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.

  14. 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.

  15. MODIS/Aqua Clear Radiance Statistics Indexed to Global Grid 5-Min L2 Swath 10km V006

    Data.gov (United States)

    National Aeronautics and Space Administration — Level 2 granule clear-sky radiance (thermal bands) and reflectance (visible bands) statistics are indexed to a global grid map. Separate statistics for day and...

  16. 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

  17. 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

  18. 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...

  19. 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...

  20. 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...

  1. 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...

  2. 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...

  3. 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...

  4. 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...

  5. 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...

  6. 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 ...

  7. 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.

  8. 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.

  9. 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

  10. 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.

  11. 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.

  12. 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

  13. 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 ...

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. A Study of Spectral Reflection on Wheat Fields in Mashhad Using MODIS Data

    Directory of Open Access Journals (Sweden)

    K. Kelarestani

    2008-10-01

    Full Text Available Remote sensing science and satellite data are widely used by researchers for agricultural studies. Vegetation spectral reflections recorded by satellite sensors have been used extensively for identifying plant types, plant cover, health community of plants and predicting yield. The TERRA satellite, with 5 sensors, provides an opportunity to observe land, atmosphere and ocean characteristics. The Moderate Resolution Imaging Spectroradiometer (MODIS is on–board TERRA satellite. This sensor with 36 bands by 250m, 500m, and 1000m spatial resolution help us to study our environment. The MODIS vegetation indices are used to monitor photosynthetic activity radiation, change detection in plant communities, planted area estimation and plant health. A statistical analysis was done to analyze Near Infra Red (NIR (841-876 nm and Red (R (620-670 nm bands of MODIS images for a 16 day period. The images have been used for winter wheat in Mashhad (North East of IRAN during agricultural season of 2004-05.Some image processing techniques were used to extract the related digital numbers (DN, showing the electromagnetic spectrum reflection for all of the pixels. The analysis shows a positive correlation between R and NIR spectrum (0.70 and 0.69 and decrease in NDVI (0.18 and 0.24 in the first and late wheat growth season. However, there is not such a good correlation in the middle of the season and NDVI increased very much. In spite of having wheat cover in the field, NIR reflection decreased very much in the late wheat growth season (0.5. Therefore the correlation relation between R and NIR band along with NDVI could be used effectively in precision agriculture management such as predicting of phonological stage, wheat yield estimation and wheat health condition.

  19. 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...

  20. 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...

  1. 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...

  2. 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...

  3. 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.

  4. 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.

  5. Mapping abandoned agriculture with multi-temporal MODIS satellite data

    DEFF Research Database (Denmark)

    Alcantara, Camilo; Kuemmerle, Tobias; Prishchepov, Alexander;

    2012-01-01

    agriculture was widespread. Input data included Normalized Difference Vegetation Index (NDVI) and reflectance bands (NASA Global MODIS Terra and Aqua 16-Day Vegetation Indices for the years 2003 through 2008, ~250-m resolution), as well as phenology metrics calculated with TIMESAT. The data were classified...... with Support Vector Machines (SVM). Training data were derived from several Landsat classifications of agricultural abandonment in the study area. A validation was conducted based on independently collected data. Our results showed that it is possible to map abandoned agriculture for large areas from MODIS...

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

    Directory of Open Access Journals (Sweden)

    Rasmus Fensholt

    2013-07-01

    Full Text Available 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 extent a known issue reported by the MODIS Land Quality Assessment group, very little is known about the scale of the issue, the nature and patterns of its occurrence, and potential consequences for data analysis, which explains why it is not adequately recognized throughout the literature. Two tropical regions were used to explore the anomaly and demonstrate the effects it has on the quality of selected MODIS products—one in the South American Amazon, the other in mainland Southeast Asia. The origins of the anomaly are described qualitatively in detail, and quantitative estimates of affected evergreen forest area in the MOD13A1 time series are made using blue band thresholding. The anomaly originates in the 1 km State dataset, whereby, under certain conditions, high aerosol quantity pixels are given a low aerosol quantity label, resulting in poor quality pixels with “good” quality labels. MODIS users are advised to investigate whether this anomaly has significant implications for their respective analysis and to consider the effects it may have on past studies.

  7. Inter-Comparison of ASTER and MODIS Surface Reflectance and Vegetation Index Products for Synergistic Applications to Natural Resource Monitoring

    Science.gov (United States)

    Miura, Tomoaki; Yoshioka, Hiroki; Fujiwara, Kayo; Yamamoto, Hirokazu

    2008-01-01

    Synergistic applications of multi-resolution satellite data have been of a great interest among user communities for the development of an improved and more effective operational monitoring system of natural resources, including vegetation and soil. In this study, we conducted an inter-comparison of two remote sensing products, namely, visible/near-infrared surface reflectances and spectral vegetation indices (VIs), from the high resolution Advanced Thermal Emission and Reflection Radiometer (ASTER) (15 m) and lower resolution Moderate Resolution Imaging Spectroradiometer (MODIS) (250 m – 500 m) sensors onboard the Terra platform. Our analysis was aimed at understanding the degree of radiometric compatibility between the two sensors' products due to sensor spectral bandpasses and product generation algorithms. Multiple pairs of ASTER and MODIS standard surface reflectance products were obtained at randomly-selected, globally-distributed locations, from which two types of VIs were computed: the normalized difference vegetation index and the enhanced vegetation indices with and without a blue band. Our results showed that these surface reflectance products and the derived VIs compared well between the two sensors at a global scale, but subject to systematic differences, of which magnitudes varied among scene pairs. An independent assessment of the accuracy of ASTER and MODIS standard products, in which “in-house” surface reflectances were obtained using in situ Aeronet atmospheric data for comparison, suggested that the performance of the ASTER atmospheric correction algorithm may be variable, reducing overall quality of its standard reflectance product. Atmospheric aerosols, which were not corrected for in the ASTER algorithm, were found not to impact the quality of the derived reflectances. Further investigation is needed to identify the sources of inconsistent atmospheric correction results associated with the ASTER algorithm, including additional quality

  8. Inter-Comparison of ASTER and MODIS Surface Reflectance and Vegetation Index Products for Synergistic Applications to Natural Resource Monitoring

    Directory of Open Access Journals (Sweden)

    Hirokazu Yamamoto

    2008-04-01

    Full Text Available Synergistic applications of multi-resolution satellite data have been of a great interest among user communities for the development of an improved and more effective operational monitoring system of natural resources, including vegetation and soil. In this study, we conducted an inter-comparison of two remote sensing products, namely, visible/near-infrared surface reflectances and spectral vegetation indices (VIs, from the high resolution Advanced Thermal Emission and Reflection Radiometer (ASTER (15 m and lower resolution Moderate Resolution Imaging Spectroradiometer (MODIS (250 m – 500 m sensors onboard the Terra platform. Our analysis was aimed at understanding the degree of radiometric compatibility between the two sensors’ products due to sensor spectral bandpasses and product generation algorithms. Multiple pairs of ASTER and MODIS standard surface reflectance products were obtained at randomly-selected, globally-distributed locations, from which two types of VIs were computed: the normalized difference vegetation index and the enhanced vegetation indices with and without a blue band. Our results showed that these surface reflectance products and the derived VIs compared well between the two sensors at a global scale, but subject to systematic differences, of which magnitudes varied among scene pairs. An independent assessment of the accuracy of ASTER and MODIS standard products, in which “in-house” surface reflectances were obtained using in situ Aeronet atmospheric data for comparison, suggested that the performance of the ASTER atmospheric correction algorithm may be variable, reducing overall quality of its standard reflectance product. Atmospheric aerosols, which were not corrected for in the ASTER algorithm, were found not to impact the quality of the derived reflectances. Further investigation is needed to identify the sources of inconsistent atmospheric correction results

  9. 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.

  10. 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.

  11. 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...

  12. Scientific Impact of MODIS C5 Calibration Degradation and C6+ Improvements

    Science.gov (United States)

    Lyapustin, A.; Wang, Y.; Xiong, X.; Meister, G.; Platnick, S.; Levy, R.; Franz, B.; Korkin, S.; Hilker, T.; 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 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 Ångstrom 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 C6C calibration of the MODIS data set which includes an additional polarization correction (PC) to compensate for the increased polarization sensitivity of MODIS Terra since about 2007, as well as detrending 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 multiangle implementation of atmospheric correction (MAIAC) algorithm over deserts, we have also developed a detrending and cross-calibration method which removes residual decadal trends on

  13. 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

  14. Impact of Sensor Degradation on the MODIS NDVI Time Series

    Science.gov (United States)

    Wang, Dongdong; Morton, Douglas Christopher; Masek, Jeffrey; Wu, Aisheng; Nagol, Jyoteshwar; Xiong, Xiaoxiong; Levy, Robert; Vermote, Eric; Wolfe, Robert

    2012-01-01

    Time series of satellite data provide unparalleled information on the response of vegetation to climate variability. Detecting subtle changes in vegetation over time requires consistent satellite-based measurements. Here, the impact of sensor degradation on trend detection was evaluated using Collection 5 data from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensors on the Terra and Aqua platforms. For Terra MODIS, the impact of blue band (Band 3, 470 nm) degradation on simulated surface reflectance was most pronounced at near-nadir view angles, leading to a 0.001-0.004 yr-1 decline in Normalized Difference Vegetation Index (NDVI) under a range of simulated aerosol conditions and surface types. Observed trends in MODIS NDVI over North America were consistentwith simulated results,with nearly a threefold difference in negative NDVI trends derived from Terra (17.4%) and Aqua (6.7%) MODIS sensors during 2002-2010. Planned adjustments to Terra MODIS calibration for Collection 6 data reprocessing will largely eliminate this negative bias in detection of NDVI trends.

  15. Scale-by-scale analysis of probability distributions for global MODIS-AQUA cloud properties: how the large scale signature of turbulence may impact statistical analyses of clouds

    Directory of Open Access Journals (Sweden)

    M. de la Torre Juárez

    2011-03-01

    Full Text Available Means, standard deviations, homogeneity parameters used in models based on their ratio, and the probability distribution functions (PDFs of cloud properties from the MODerate resolution Infrared Spectrometer (MODIS are estimated globally as function of averaging scale varying from 5 to 500 km. The properties – cloud fraction, droplet effective radius, and liquid water path – all matter for cloud-climate uncertainty quantification and reduction efforts. Global means and standard deviations are confirmed to change with scale. For the range of scales considered, global means vary only within 3% for cloud fraction, 7% for liquid water path, and 0.2% for cloud particle effective radius. These scale dependences contribute to the uncertainties in their global budgets. Scale dependence for standard deviations and generalized flatness are compared to predictions for turbulent systems. Analytical expressions are identified that fit best to each observed PDF. While the best analytical PDF fit to each variable differs, all PDFs are well described by log-normal PDFs when the mean is normalized by the standard deviation inside each averaging domain. Importantly, log-normal distributions yield significantly better fits to the observations than gaussians at all scales. This suggests a possible approach for both sub-grid and unified stochastic modeling of these variables at all scales. The results also highlight the need to establish an adequate spatial resolution for two-stream radiative studies of cloud-climate interactions.

  16. 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

  17. 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

  18. 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...

  19. 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.

  20. 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.

  1. 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...

  2. 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.

  3. 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

  4. 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.

  5. 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.

  6. 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.

  7. 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...

  8. 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.

  9. Estimating spectral albedo and nadir reflectance through inversion of simple BRDF models with AVHRR/MODIS-like data

    Science.gov (United States)

    Privette, Jeffrey L.; Eck, Thomas F.; Deering, Donald W.

    1997-12-01

    In recent years, many computationally efficient bidirectional reflectance models have been developed to account for angular effects in land remote sensing data, particularly those from the NOAA advanced very high resolution radiometer (AVHRR), polarization and directionality of the Earth's reflectances (POLDER), and the planned EOS moderate-resolution imaging spectrometer (MODIS) and multi-angle imaging spectroradiometer (MISR) sensors. In this study, we assessed the relative ability of 10 such models to predict commonly used remote sensing products (nadir reflectance and albedo). Specifically, we inverted each model with ground-based data from the portable apparatus for rapid acquisition of bidirectional observations of the land and atmosphere (PARABOLA) arranged in subsets representative of satellite sampling geometries. We used data from nine land cover types, ranging from soil to grassland (First International Satellite Land Surface Climatology Project (ISLSCP) Field Experiment (FIFE)) to forest (Boreal Ecosystem-Atmosphere Study (BOREAS)). Retrieved parameters were used in forward model runs to estimate nadir reflectance and spectral albedo over a wide range of solar angles. We rank the models by the accuracy of the estimated products and find results to be strongly dependent on the view azimuth angle range of the inversion data, and less dependent on the spectral band and land cover type. Overall, the nonlinear model of Rahman et al. [993] and the linear kernel-driven RossThickLiSparse model [Wanner et al., 1995] were most accurate. The latter was at least 25 times faster to invert than the former. Interestingly, we found these two models were not able to match the various bidirectional reflectance distribution function (BRDF) shapes as well as other models, suggesting their superior performance lies in their ability to be more reliably inverted with sparse data sets. These results should be useful to those interested in the computationally fast normalization

  10. 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。

  11. 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.

  12. 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

  13. 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.

  14. 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

  15. 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.

  16. 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).

  17. 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.

  18. 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.

  19. 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...

  20. 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...

  1. 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.

  2. 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...

  3. 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...

  4. 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.

  5. MODIS instrument status and operational activities

    Science.gov (United States)

    Barnes, William L.; Xiong, Xiaoxiong; Salomonson, Vincent V.

    2004-10-01

    The Terra MODIS and Aqua MODIS have been successfully operated on-orbit for a total of more than six and a half years, collecting data for the science and applications communities to develop and enhance their understanding of the Earth/atmosphere system and to support studies of the climate and climate changes. Since its launch in December 1999, the Terra MODIS has experienced several changes of its operational configuration either caused by the failure of individual electronics subsystems or purposely switched for better signal response or data quality. Excluding minor anomalies related to instrument reset events during initial on-orbit operation, the Aqua MODIS has been operating in a single configuration since its launch in May 2002. There are approximately 40 science products that are being produced using the calibrated data sets from each instrument. In addition, several products are generated using the combined observations from both instruments. This paper provides an overview of Terra and Aqua MODIS instrument status and summarizes those on-orbit operational activities designed and implemented to provide and support instrument calibration and characterization. The assessments of instrument performance are based on the use of on-board calibrators (OBC) and other activities specially developed and implemented by the MODIS Characterization Support Team (MCST) at NASA/GSFC. Both instruments are performing well. During four and a half years of Terra MODIS on-orbit operation, 11 detectors became noisy and one inoperable out of a total of 490 detectors. Except for band 6 at 1.6m that had many inoperable detectors (identified pre-launch and immediately after launch), there have been no new noisy or inoperable detectors in Aqua MODIS during its two years of on-orbit operation. The sensors' spectral and spatial performance have also been very stable.

  6. 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.

  7. 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

  8. 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.

  9. The MODIS Vegetation Canopy Water Content product

    Science.gov (United States)

    Ustin, S. L.; Riano, D.; Trombetti, M.

    2008-12-01

    Vegetation water stress drives wildfire behavior and risk, having important implications for biogeochemical cycling in natural ecosystems, agriculture, and forestry. Water stress limits plant transpiration and carbon gain. The regulation of photosynthesis creates close linkages between the carbon, water, and energy cycles and through metabolism to the nitrogen cycle. We generated systematic weekly CWC estimated for the USA from 2000-2006. MODIS measures the sunlit reflectance of the vegetation in the visible, near-infrared, and shortwave infrared. Radiative transfer models, such as PROSPECT-SAILH, determine how sunlight interacts with plant and soil materials. These models can be applied over a range of scales and ecosystem types. Artificial Neural Networks (ANN) were used to optimize the inversion of these models to determine vegetation water content. We carried out multi-scale validation of the product using field data, airborne and satellite cross-calibration. An Algorithm Theoretical Basis Document (ATBD) of the product is under evaluation by NASA. The CWC product inputs are 1) The MODIS Terra/Aqua surface reflectance product (MOD09A1/MYD09A1) 2) The MODIS land cover map product (MOD12Q1) reclassified to grassland, shrub-land and forest canopies; 3) An ANN trained with PROSPECT-SAILH; 4) A calibration file for each land cover type. The output is an ENVI file with the CWC values. The code is written in Matlab environment and is being adapted to read not only the 8 day MODIS composites, but also daily surface reflectance data. We plan to incorporate the cloud and snow mask and generate as output a geotiff file. Vegetation water content estimates will help predicting linkages between biogeochemical cycles, which will enable further understanding of feedbacks to atmospheric concentrations of greenhouse gases. It will also serve to estimate primary productivity of the biosphere; monitor/assess natural vegetation health related to drought, pollution or diseases

  10. 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%.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. Aqua Education and Public Outreach

    Science.gov (United States)

    Graham, S. M.; Parkinson, C. L.; Chambers, L. H.; Ray, S. E.

    2011-12-01

    NASA's Aqua satellite was launched on May 4, 2002, with six instruments designed to collect data about the Earth's atmosphere, biosphere, hydrosphere, and cryosphere. Since the late 1990s, the Aqua mission has involved considerable education and public outreach (EPO) activities, including printed products, formal education, an engineering competition, webcasts, and high-profile multimedia efforts. The printed products include Aqua and instrument brochures, an Aqua lithograph, Aqua trading cards, NASA Fact Sheets on Aqua, the water cycle, and weather forecasting, and an Aqua science writers' guide. On-going formal education efforts include the Students' Cloud Observations On-Line (S'COOL) Project, the MY NASA DATA Project, the Earth System Science Education Alliance, and, in partnership with university professors, undergraduate student research modules. Each of these projects incorporates Aqua data into its inquiry-based framework. Additionally, high school and undergraduate students have participated in summer internship programs. An earlier formal education activity was the Aqua Engineering Competition, which was a high school program sponsored by the NASA Goddard Space Flight Center, Morgan State University, and the Baltimore Museum of Industry. The competition began with the posting of a Round 1 Aqua-related engineering problem in December 2002 and concluded in April 2003 with a final round of competition among the five finalist teams. The Aqua EPO efforts have also included a wide range of multimedia products. Prior to launch, the Aqua team worked closely with the Special Projects Initiative (SPI) Office to produce a series of live webcasts on Aqua science and the Cool Science website aqua.nasa.gov/coolscience, which displays short video clips of Aqua scientists and engineers explaining the many aspects of the Aqua mission. These video clips, the Aqua website, and numerous presentations have benefited from dynamic visualizations showing the Aqua launch

  16. 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 ...

  17. 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.

  18. 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.

  19. AquaBuOY

    DEFF Research Database (Denmark)

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

    2003-01-01

    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 Aqua......BuOY in five representative generic sea states. Ocean energy and offshore wave energy conversion in the United States is at a significant milestone. During the next year, ocean energy technology developers and energy officials have the potential to deploy pilot scale ocean power plants and transition to...... commercial plants in the US. This capability comes at a time of increased interest in ocean energies at the National Academy of Sciences and the US Department of Energy. AquaEnergy will conclude its presentation with a brief overview of current legislation affecting the industry. In 2004, ocean scientists...

  20. 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.

  1. 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

  2. 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...

  3. 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...

  4. 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...

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

    OpenAIRE

    Yonghua Qu; Wenchao Han; Mingguo Ma

    2014-01-01

    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, ...

  6. Inter-Comparison of ASTER and MODIS Surface Reflectance and Vegetation Index Products for Synergistic Applications to Natural Resource Monitoring

    OpenAIRE

    Hirokazu Yamamoto; Kayo Fujiwara; Hiroki Yoshioka; Tomoaki Miura

    2008-01-01

    Synergistic applications of multi-resolution satellite data have been of a great interest among user communities for the development of an improved and more effective operational monitoring system of natural resources, including vegetation and soil. In this study, we conducted an inter-comparison of two remote sensing products, namely, visible/near-infrared surface reflectances and spectral vegetation indices (VIs), from the high resolution Advanced Thermal Emission and Reflection Radiometer ...

  7. 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. ...

  8. 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.

  9. 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 ...

  10. 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...

  11. 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

  12. 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

  13. Detection rates of the MODIS active fire product in the United States

    Science.gov (United States)

    Hawbaker, T.J.; Radeloff, V.C.; Syphard, A.D.; Zhu, Z.; Stewart, S.I.

    2008-01-01

    MODIS active fire data offer new information about global fire patterns. However, uncertainties in detection rates can render satellite-derived fire statistics difficult to interpret. We evaluated the MODIS 1??km daily active fire product to quantify detection rates for both Terra and Aqua MODIS sensors, examined how cloud cover and fire size affected detection rates, and estimated how detection rates varied across the United States. MODIS active fire detections were compared to 361 reference fires (??? 18??ha) that had been delineated using pre- and post-fire Landsat imagery. Reference fires were considered detected if at least one MODIS active fire pixel occurred within 1??km of the edge of the fire. When active fire data from both Aqua and Terra were combined, 82% of all reference fires were found, but detection rates were less for Aqua and Terra individually (73% and 66% respectively). Fires not detected generally had more cloudy days, but not when the Aqua data were considered exclusively. MODIS detection rates decreased with fire size, and the size at which 50% of all fires were detected was 105??ha when combining Aqua and Terra (195??ha for Aqua and 334??ha for Terra alone). Across the United States, detection rates were greatest in the West, lower in the Great Plains, and lowest in the East. The MODIS active fire product captures large fires in the U.S. well, but may under-represent fires in areas with frequent cloud cover or rapidly burning, small, and low-intensity fires. We recommend that users of the MODIS active fire data perform individual validations to ensure that all relevant fires are included. ?? 2008 Elsevier Inc. All rights reserved.

  14. 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.

  15. 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....

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

    Science.gov (United States)

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

    2015-05-01

    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.

  17. 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.

  18. 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...

  19. 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...

  20. 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

  1. 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...

  2. 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...

  3. 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...

  4. 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...

  5. 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...

  6. 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...

  7. 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...

  8. 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...

  9. 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...

  10. 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...

  11. 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.

  12. 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...

  13. 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...

  14. 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.

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

    Science.gov (United States)

    Levy, R. C.; Munchak, L. A.; Mattoo, S.; Patadia, F.; Remer, L. A.; Holz, R. E.

    2015-10-01

    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 Ångström 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, especially in

  16. 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

  17. 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.

  18. 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.

  19. 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.)

  20. 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

  1. Comparison of ASTER TOA Radiance with MODIS

    Science.gov (United States)

    Kanno, Hiroto; Iwasaki, Akira

    Synergistic fusion of multi-resolution remote sensing images is important to data users that require observation frequency, spatial resolution and observation wavelength. However, it requires compatibility of these data products. Top of Atmosphere (TOA) radiances of the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) and the Moderate Resolution Imaging Spectroradiometer (MODIS) are compared in the shortwave infrared (SWIR) and it is found that the sensitivity of MODIS is slightly higher and that the ASTER radiance is higher at the lower reflectance regions. ASTER suffers from stray light phenomena because of the nature of a pushbroom sensor, which stands out for SWIR. In contrast, MODIS is free from ghost phenomena in reflective bands, although existence of stray light is known in thermal bands. In this work, correction of stray light in ASTER is carried out using MODIS images with a wider swath, which makes the correction of full scene of ASTER images.

  2. Monitoring agricultural burning in the Mississippi River Valley region from the moderate resolution imaging spectroradiometer (MODIS).

    Science.gov (United States)

    Korontzi, Stefania; McCarty, Jessica; Justice, Christopher

    2008-09-01

    The 2003 active fire observations from the Moderate Resolution Imaging Spectroradiometer (MODIS), on board NASA's Terra and Aqua satellites, were analyzed to assess burning activity in the cropland areas of the Mississippi River Valley region. Agricultural burning was found to be an important contributor to fire activity in this region, accounting for approximately one-third of all burning. Agricultural fire activity showed two seasonal peaks: the first, smaller peak, occurring in June during the spring harvesting of wheat; and the second, bigger peak, in October during the fall harvesting of rice and soy. The seasonal signal in agricultural burning was predominantly evident in the early afternoon MODIS Aqua fire detections. A strong diurnal agricultural fire signal was prevalent during the fall harvesting months, as suggested by the substantially higher number (approximately 3.5 times) of fires detected by MODIS Aqua in the early afternoon, compared with those detected by MODIS Terra in the morning. No diurnal variations in agricultural fire activity were apparent during the springtime wheat-harvesting season. The seasonal and diurnal patterns in agricultural fire activity detected by MODIS are supported by known crop management practices in this region. MODIS data provide an important means to characterize and monitor agricultural fire dynamics and management practices. PMID:18817116

  3. 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...

  4. Snow Cover Maps from MODIS Images at 250 m Resolution, Part 1: Algorithm Description

    Directory of Open Access Journals (Sweden)

    Claudia Notarnicola

    2013-01-01

    Full Text Available A new algorithm for snow cover monitoring at 250 m resolution based on Moderate Resolution Imaging Spectroradiometer (MODIS images is presented. In contrast to the 500 m resolution MODIS snow products of NASA (MOD10 and MYD10, the main goal was to maintain the resolution as high as possible to allow for a more accurate detection of snow covered area (SCA. This is especially important in mountainous regions characterized by extreme landscape heterogeneity, where maps at a resolution of 500 m could not provide the desired amount of spatial details. Therefore, the algorithm exploits only the 250 m resolution bands of MODIS in the red (B1 and infrared (B2 spectrum, as well as the Normalized Difference Vegetation Index (NDVI for snow detection, while clouds are classified using also bands at 500 m and 1 km resolution. The algorithm is tailored to process MODIS data received in real-time through the EURAC receiving station close to Bolzano, Italy, but also standard MODIS products are supported. It is divided into three steps: first the data is preprocessed, including reprojection, calculation of physical reflectance values and masking of water bodies. In a second step, the actual classification of snow, snow in forested areas, and clouds takes place based on MODIS images both from Terra and Aqua satellites. In the third step, snow cover maps derived from images of both sensors of the same day are combined to reduce cloud coverage in the final SCA product. Four different quality indices are calculated to verify the reliability of input data, snow classification, cloud detection and viewing geometry. Using the data received through their own station, EURAC can provide SCA maps of central Europe to end users in near real-time. Validation of the algorithm is outlined in a companion paper and indicates good performance with accuracies ranging from 94% to around 82% compared to in situ snow depth measurements, and around 93% compared to SCA derived from

  5. 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

  6. 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...

  7. In aqua vivo EPID dosimetry

    International Nuclear Information System (INIS)

    Purpose: At the Netherlands Cancer Institute-Antoni van Leeuwenhoek Hospital in vivo dosimetry using an electronic portal imaging device (EPID) has been implemented for almost all high-energy photon treatments of cancer with curative intent. Lung cancer treatments were initially excluded, because the original back-projection dose-reconstruction algorithm uses water-based scatter-correction kernels and therefore does not account for tissue inhomogeneities accurately. The aim of this study was to test a new method, in aqua vivo EPID dosimetry, for fast dose verification of lung cancer irradiations during actual patient treatment. Methods: The key feature of our method is the dose reconstruction in the patient from EPID images, obtained during the actual treatment, whereby the images have been converted to a situation as if the patient consisted entirely of water; hence, the method is termed in aqua vivo. This is done by multiplying the measured in vivo EPID image with the ratio of two digitally reconstructed transmission images for the unit-density and inhomogeneous tissue situation. For dose verification, a comparison is made with the calculated dose distribution with the inhomogeneity correction switched off. IMRT treatment verification is performed for each beam in 2D using a 2D γ evaluation, while for the verification of volumetric-modulated arc therapy (VMAT) treatments in 3D a 3D γ evaluation is applied using the same parameters (3%, 3 mm). The method was tested using two inhomogeneous phantoms simulating a tumor in lung and measuring its sensitivity for patient positioning errors. Subsequently five IMRT and five VMAT clinical lung cancer treatments were investigated, using both the conventional back-projection algorithm and the in aqua vivo method. The verification results of the in aqua vivo method were statistically analyzed for 751 lung cancer patients treated with IMRT and 50 lung cancer patients treated with VMAT. Results: The improvements by applying

  8. In aqua vivo EPID dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Wendling, Markus; McDermott, Leah N.; Mans, Anton; Olaciregui-Ruiz, Igor; Pecharroman-Gallego, Raul; Sonke, Jan-Jakob; Stroom, Joep; Herk, Marcel J.; Mijnheer, Ben van [Department of Radiation Oncology, Netherlands Cancer Institute-Antoni van Leeuwenhoek Hospital, Plesmanlaan 121, 1066 CX Amsterdam (Netherlands)

    2012-01-15

    Purpose: At the Netherlands Cancer Institute-Antoni van Leeuwenhoek Hospital in vivo dosimetry using an electronic portal imaging device (EPID) has been implemented for almost all high-energy photon treatments of cancer with curative intent. Lung cancer treatments were initially excluded, because the original back-projection dose-reconstruction algorithm uses water-based scatter-correction kernels and therefore does not account for tissue inhomogeneities accurately. The aim of this study was to test a new method, in aqua vivo EPID dosimetry, for fast dose verification of lung cancer irradiations during actual patient treatment. Methods: The key feature of our method is the dose reconstruction in the patient from EPID images, obtained during the actual treatment, whereby the images have been converted to a situation as if the patient consisted entirely of water; hence, the method is termed in aqua vivo. This is done by multiplying the measured in vivo EPID image with the ratio of two digitally reconstructed transmission images for the unit-density and inhomogeneous tissue situation. For dose verification, a comparison is made with the calculated dose distribution with the inhomogeneity correction switched off. IMRT treatment verification is performed for each beam in 2D using a 2D {gamma} evaluation, while for the verification of volumetric-modulated arc therapy (VMAT) treatments in 3D a 3D {gamma} evaluation is applied using the same parameters (3%, 3 mm). The method was tested using two inhomogeneous phantoms simulating a tumor in lung and measuring its sensitivity for patient positioning errors. Subsequently five IMRT and five VMAT clinical lung cancer treatments were investigated, using both the conventional back-projection algorithm and the in aqua vivo method. The verification results of the in aqua vivo method were statistically analyzed for 751 lung cancer patients treated with IMRT and 50 lung cancer patients treated with VMAT. Results: The improvements by

  9. 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.

  10. 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...

  11. 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

  12. 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.

  13. 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

  14. Comparison of the MODIS Collection 5 Multilayer Cloud Detection Product with CALIPSO

    Science.gov (United States)

    Platnick, Steven; Wind, Gala; King, Michael D.; Holz, Robert E.; Ackerman, Steven A.; Nagle, Fred W.

    2010-01-01

    CALIPSO, launched in June 2006, provides global active remote sensing measurements of clouds and aerosols that can be used for validation of a variety of passive imager retrievals derived from instruments flying on the Aqua spacecraft and other A-Train platforms. The most recent processing effort for the MODIS Atmosphere Team, referred to as the Collection 5 scream, includes a research-level multilayer cloud detection algorithm that uses both thermodynamic phase information derived from a combination of solar and thermal emission bands to discriminate layers of different phases, as well as true layer separation discrimination using a moderately absorbing water vapor band. The multilayer detection algorithm is designed to provide a means of assessing the applicability of 1D cloud models used in the MODIS cloud optical and microphysical product retrieval, which are generated at a 1 km resolution. Using pixel-level collocations of MODIS Aqua, CALIOP, we investigate the global performance of multilayer cloud detection algorithms (and thermodynamic phase).

  15. 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

  16. 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...

  17. 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 ...

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. Results of MODIS Band-to-Band Registration Characterization Using On-Orbit Lunar Observations

    Science.gov (United States)

    Xiong, Xiaoxiong; Sun, Junqiang; Angal,Amit

    2011-01-01

    Since launch, lunar observations have been made regularly by both Terra and Aqua MODIS and used for a number of sensor calibration and characterization related applications, including radiometric stability monitoring, spatial characterization, optical leak and electronic cross-talk characterization, and calibration inter-comparison. MODIS has 36 spectral bands with a total of 490 individual detectors. They are located on four focal plane assemblies (FPA). This paper focuses on the use of MODIS lunar observations to characterize its band-to-band registration (BBR). In addition to BBR, the approach developed by the MODIS Characterization Support Team (MCST) can be used to characterize MODIS detector-to-detector registration (DDR). Long-term BBR results developed from this approach are presented and compared with that derived from a unique on-board calibrator (OBC). Results show that on-orbit changes of BBR have been very small for both Terra and Aqua MODIS and this approach can be applied to other remote sensing instruments.

  4. 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

  5. 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 ://...

  6. 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,...

  7. 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,...

  8. 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,...

  9. Assessment of MODIS on-orbit spatial performance

    Science.gov (United States)

    Link, Daniel; Xiong, Xiaoxiong J.; Wang, Zhipeng

    2015-10-01

    The Terra and Aqua satellites are part of NASA's Earth Observing System and both satellites host a nearly-identical Moderate Resolution Imaging Spectroradiometer (MODIS). Of the 36 MODIS spectral bands mounted among four Focal Plane Assemblies (FPAs) two have a 250 meter spatial resolution at nadir. Five bands have a spatial resolution of 500 meters, while the remaining bands make observations at 1 kilometer resolution. MODIS is equipped with a suite of onboard calibrators to track on-orbit changes in key sensor performance parameters. The Spectro-Radiometric Calibration Assembly (SRCA) contains a calibration source that allows on-orbit assessment of MODIS spatial performance, providing information on current band-to-band registration (BBR), FPA-to-FPA registration (FFR), detector-to-detector registration (DDR), modulation transfer function (MTF), and instantaneous field-of-view (IFOV). In this paper, we present the methodology of the on-orbit spatial calibrations using SRCA and the results of these key spatial parameters. The MODIS spatial characteristics, measured on-orbit, are compared against design specifications and pre-launch measurements.

  10. 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....

  11. 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....

  12. 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.

  13. 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

  14. 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.

  15. 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.

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

    OpenAIRE

    Nichol, Janet E.; Muhammad Bilal

    2016-01-01

    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...

  17. 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.

  18. 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...

  19. 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...

  20. 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...

  1. 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.

  2. 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.

  3. 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

  4. 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

  5. Land Surface Temperature Measurements from EOS MODIS Data

    Science.gov (United States)

    Wan, Zheng-Ming

    2004-01-01

    This report summarizes the accomplishments made by the MODIS LST (Land-Surface Temperature) group at University of California, Santa Barbara, under NASA Contract. Version 1 of the MODIS Land-Surface Temperature Algorithm Theoretical Basis Document (ATBD) was reviewed in June 1994, version 2 reviewed in November 1994, version 3.1 in August 1996, and version 3.3 updated in April 1999. Based on the ATBD, two LST algorithms were developed, one is the generalized split-window algorithm and another is the physics-based day/night LST algorithm. These two LST algorithms were implemented into the production generation executive code (PGE 16) for the daily standard MODIS LST products at level-2 (MODII-L2) and level-3 (MODIIA1 at 1 km resolution and MODIIB1 at 5km resolution). PGE codes for 8-day 1 km LST product (MODIIA2) and the daily, 8-day and monthly LST products at 0.05 degree latitude/longitude climate model grids (CMG) were also delivered. Four to six field campaigns were conducted each year since 2000 to validate the daily LST products generated by PGE16 and the calibration accuracies of the MODIS TIR bands used for the LST/emissivity retrieval from versions 2-4 of Terra MODIS data and versions 3-4 of Aqua MODIS data. Validation results from temperature-based and radiance-based methods indicate that the MODIS LST accuracy is better than 1 C in most clear-sky cases in the range from -10 to 58 C. One of the major lessons learn from multi- year temporal analysis of the consistent V4 daily Terra MODIS LST products in 2000-2003 over some selected target areas including lakes, snow/ice fields, and semi-arid sites is that there are variable numbers of cloud-contaminated LSTs in the MODIS LST products depending on surface elevation, land cover types, and atmospheric conditions. A cloud-screen scheme with constraints on spatial and temporal variations in LSTs was developed to remove cloud-contaminated LSTs. The 5km LST product was indirectly validated through comparisons to

  6. 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.

  7. 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...

  8. 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...

  9. 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

  10. 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.

  11. 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

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

    Science.gov (United States)

    Suzuki, R.; Nagai, S.

    2014-12-01

    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

  13. 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.

  14. Therapeutic performances of some selected aqua drugs

    OpenAIRE

    Rasheduzzaman Khan Dipu; Md. Bazlur Rashid Chowdhury; Mohammad Abdullah Al Imran; Md. Abdul Quaiyum; Md. Tareq-Uz-Zaman

    2014-01-01

    This study was carried out at the Disease Laboratory of the Faculty of Fisheries, Bangladesh Agricultural University, Mymensingh, Bangladesh to verify the therapeutic performances of six commercial aqua drugs; three doses were selected as less than recommended, recommended and more than recommended to assess their performances. Before starting therapeutic experimental nine climbing perch (Anabas testudineus) and six stinging catfish (Heteropneustes fossilis) were confirmed as diseased ones by...

  15. 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

  16. 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.

  17. 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...

  18. 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

  19. 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

  20. Cryosphere Broadband Surface Albedo Derivation with MODIS-to-CERES Conversion

    Science.gov (United States)

    Radkevich, A.; Rose, F. G.; Charlock, T. P.; Kato, S.

    2011-12-01

    Clouds and the Earth's Radiant Energy System (CERES) instruments on NASA's Earth Observing System (EOS) Terra and Aqua satellites measure broadband shortwave and longwave radiation reflected and emitted at the Top of the atmosphere (TOA). CERES synthesizes broadband observations with other EOS data streams. The CERES Surface and Atmospheric Radiation Budget (SARB) group matches observations with a radiative transfer code to determine fluxes at several levels. The presentation describes how the next edition of CERES will improve the retrieval of cryosphere surface albedo. Surface albedo is one of the input parameters of numerous models such cloud-resolving model (CRM) simulation, general circulation models (GCMs) and transient climate change simulations. It was recently showed by Park and Wu (2010) that CRM simulation well represents the SW radiative budget during winter because the radiation calculation for the snow-covered period is improved by using prescribed evolving surface albedo. Qu and Hall (2007) analyzed snow albedo feedback (SAF) in several transient climate change models. They stated that high quality observations of albedo of snow-covered surfaces would be extremely useful in reducing SAF spread in the next generation of models. CERES measures radiance and infers flux by applying scene-dependent, empirically based angular distribution models (ADMs). The ADMs are obtained from the complex CERES rotating azimuth plane scan mode to establish BRDF on the scale of 30 km broadband footprints. While CERES has much coarser spatial resolution than MODIS, the CERES measurement-based BRDF provides a keen advantage in accuracy over complex surfaces. CERES SARB retrievals of surface albedo have to date been based on only those 30 km footprints that are completely clear; there are too few (~5%) such footprints over sea ice. The upcoming edition of CERES will include MODIS radiances in 7 SW bands (currently 4), which are point spread function weighted to both a whole

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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...

  7. 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.

  8. 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.

  9. 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 ...

  10. Therapeutic performances of some selected aqua drugs

    Directory of Open Access Journals (Sweden)

    Rasheduzzaman Khan Dipu

    2014-08-01

    Full Text Available This study was carried out at the Disease Laboratory of the Faculty of Fisheries, Bangladesh Agricultural University, Mymensingh, Bangladesh to verify the therapeutic performances of six commercial aqua drugs; three doses were selected as less than recommended, recommended and more than recommended to assess their performances. Before starting therapeutic experimental nine climbing perch (Anabas testudineus and six stinging catfish (Heteropneustes fossilis were confirmed as diseased ones by their clinical signs. The backswimmers (Notonecta glauca were collected from faculty of fisheries pond and fish louses (Argulus sp. were collected from tilapia fishes. Effective doses and their performances were determined on the basis of desired water quality change and clinical signs. It was found that all the drugs performed better at more than recommended doses as follows Aqua Ox performed better at the rate of 0.2 mg/l, GR Plus, 0.0005 ml/l, ID Plus (5%, 0.00026 ml/l; Active Blue, 0.0002 ml/l; Hashpoka Killer, 0.0001 ml/l; and Para Control, 0.001 ml/l. So these doses were suggested as recommended doses.

  11. 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.

  12. Analysis of co-located MODIS and CALIPSO observations near clouds

    Directory of Open Access Journals (Sweden)

    T. Várnai

    2011-11-01

    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 imager can refine our perceptions based on CALIOP 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 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. The global median distance to clouds in maritime clear-sky areas is in the 4–5 km range.

  13. 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.

  14. 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.

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

    Directory of Open Access Journals (Sweden)

    M. de la Torre Juárez

    2009-02-01

    Full Text Available 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 vertically homogeneous distributions of cloud water content in the MODIS LWP retrieval yields a slightly poorer agreement than the assumption of stratified cloud liquid water. Furthermore, for a fixed cloud top pressure, the cloud top temperature can lead to sign changes in the LWP difference. In general, AMSR-E LWP is larger than MODIS for small cloud fractions, low values of LWP, and warmer cloud top temperatures. On the other hand, clouds with optical thicknesses above 20 lead to larger MODIS LWP. Using cloud optical thickness as a proxy for cloud type, deep convective clouds and stratus are shown to have the poorest agreement between AMSR-E and MODIS LWP. Particularly large differences are also found at latitudes poleward of 50°. The results of this work help characterize the scene- and cloud-dependent performance of microwave and visible/near infrared retrievals of LWP.

  16. 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

  17. 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.

  18. 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

  19. 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.

  20. 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.

  1. Estimation of water turbidity and analysis of its spatio-temporal variability in the Danube River plume (Black Sea) using MODIS satellite data

    Science.gov (United States)

    Constantin, Sorin; Doxaran, David; Constantinescu, Ștefan

    2016-01-01

    Ocean colour remote sensing information brings important insights for monitoring coastal areas. These regions are home to important natural ecosystems and changes that occur here can have important impacts not only on the local environment, but also on connected wetlands or offshore areas. The present study proposes a new regional methodology for water turbidity retrieval using the MODIS red band at 250 m spatial resolution in the Danube Delta coastal area. For this purpose, multiple in-situ turbidity observations were used in order to determine a valid relationship between data collected with turbidity meters and remote sensing reflectance obtained from satellite data. A special attention is given to the atmospheric correction of satellite data, since complex optical waters require adapted methodologies for accurate remote sensing reflectance computation. Based on products derived using the proposed algorithm, the dynamics of turbidity is evaluated for multiple time periods: from local Terra to Aqua overpasses (couple of hours), daily and monthly. Results show a clear strong connection between the Danube discharge and water turbidity in the coastal area. However other environmental parameters (e.g., wind stress) also play an important role and contribute to the magnitude of the river plume extension.

  2. 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.

  3. 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.

  4. 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

  5. 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...

  6. 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...

  7. 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...

  8. 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.

  9. Evaluation of Aerosol Optical Depth by AERONET, MODIS and MISR over the Mediterranean and Middle East in 2006.

    Science.gov (United States)

    de Meij, Alexander; Lelieveld, Jos

    2010-05-01

    The objective of this study is to evaluate the spatial and temporal variation of the aerosol optical depth (AOD) and to identify the main characteristics of the aerosol episodes for the Mediterranean area, with the focus on the year 2006. We evaluate aerosol optical properties of MODIS and MISR instruments with AERONET. In general the yearly mean MODIS and MISR AOD is in good agreement with AERONET and the temporal AOD variation is also in good agreement. High AODs observed by AERONET, MODIS and MISR are caused by natural dust events or high anthropogenic aerosol concentrations in the combination with stagnant meteorological conditions. The comparison of MODIS and MISR aerosol optical properties with AERONET for June reveals that the AODs, Angstrom coefficients and single scattering albedos agree well with AERONET and indicate the presence of natural dust in the Mediterranean. In general MISR AOD is lower than MODIS AOD during summer. Comparing MODIS Aqua Deep Blue with MISR for June over the Saharan desert reveals some differences in the location and the maxima of the AOD values. The seasonal AOD variation by MISR over the Mediterranean and Middle East shows substantial differences in the AODs for each season. Higher dust loads during spring and autumn time in the eastern part of the Mediterranean. Biomass burning activities around the Black Sea during July and August (e.g. agricultural waste burning) cause high AODs and the particles are transported to the eastern part of the Mediterranean, because of the dominant northerly wind direction during summer.

  10. 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).

  11. 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.

  12. 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.

  13. 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...

  14. 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.

  15. 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.

  16. 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.

  17. 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 ...

  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. 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).

  1. 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.

  2. MODIS Global Sea Surface Temperature

    Science.gov (United States)

    2002-01-01

    Every day the Moderate-resolution Imaging Spectroradiometer (MODIS) measures sea surface temperature over the entire globe with high accuracy. This false-color image shows a one-month composite for May 2001. Red and yellow indicates warmer temperatures, green is an intermediate value, while blues and then purples are progressively colder values. The new MODIS sea surface temperature product will be particularly useful in studies of temperature anomalies, such as El Nino, as well as research into how air-sea interactions drive changes in weather and climate patterns. In the high resolution image, notice the amazing detail in some of the regional current patterns. For instance, notice the cold water currents that move from Antarctica northward along South America's west coast. These cold, deep waters upwell along an equatorial swath around and to the west of the Galapagos Islands. Note the warm, wide currents of the Gulf Stream moving up the United States' east coast, carrying Caribbean warmth toward Newfoundland and across the Atlantic toward Western Europe. Note the warm tongue of water extending from Africa's east coast to well south of the Cape of Good Hope. MODIS was launched in December 1999 aboard NASA's Terra satellite. For more details on this and other MODIS data products, please see NASA Unveils Spectacular Suite of New Global Data Products from MODIS. Image courtesy MODIS Ocean Group, NASA GSFC, and the University of Miami

  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. 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.

  5. 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.

  6. 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

  7. 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.

  8. 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

    -sensor geometry variations will have a more visible impact on the Normalized Difference Vegetation Index (NDVI) from MODIS compared to earlier data sources, since noise related to atmosphere and sensor calibration is substantially reduced in the MODIS data stream. For this reason, the effect of varying MODIS...... 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...... reflectances depends on the amount of vegetation present. MODIS VZA and RAA effects on NDVI were highest for medium dense vegetation (NDVI approximate to 0.5-0.6). The VZA and RAA effects were less for sparsely vegetated areas (NDVI approximate to 0.3-0.35) and the smallest effect on NDVI was found for dense...

  9. Comparison of the MODIS Multilayer Cloud Detection and Thermodynamic Phase Products with CALIPSO and CloudSat

    Science.gov (United States)

    Platnick, Steven; King, Michael D.; Wind, Gala; Holz, Robert E.; Ackerman, Steven A.; Nagle, Fred W.

    2008-01-01

    CALIPSO and CloudSat, launched in June 2006, provide global active remote sensing measurements of clouds and aerosols that can be used for validation of a variety of passive imager retrievals derived from instruments flying on the Aqua spacecraft and other A-Train platforms. The most recent processing effort for the MODIS Atmosphere Team, referred to as the "Collection 5" stream, includes a research-level multilayer cloud detection algorithm that uses both thermodynamic phase information derived from a combination of solar and thermal emission bands to discriminate layers of different phases, as well as true layer separation discrimination using a moderately absorbing water vapor band. The multilayer detection algorithm is designed to provide a means of assessing the applicability of 1D cloud models used in the MODIS cloud optical and microphysical product retrieval, which are generated at a 1 h resolution. Using pixel-level collocations of MODIS Aqua, CALIOP, and CloudSat radar measurements, we investigate the global performance of the thermodynamic phase and multilayer cloud detection algorithms.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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

  15. 15 Years of Terra MODIS Instrument on-Orbit Performance

    Science.gov (United States)

    Xiong, X.; Salomonson, V.

    2014-12-01

    The first MODIS instrument, launched on-board the NASA EOS Terra spacecraft in December 1999, has successfully operated for nearly 15 years. MODIS observations have significantly contributed to the studies of many geophysical parameters of the earth's system and its changes over time. Dedicated effort made by the MODIS Characterization Support Team (MCST) to constantly monitor instrument operation, to calibrate changes in sensor response, to derive and update sensor calibration parameters, and to maintain and improve calibration algorithms has played an extremely important role to assure the quality of MODIS data products. MODIS was developed with overall improvements over its heritage sensors. Its observations are made in 36 spectral bands, covering wavelengths from visible to long-wave infrared. The reflective solar bands (1-19 and 26) are calibrated on-orbit 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 tracked by a spectroradiometric calibration assembly (SRCA). This paper provides an overview of Terra MODIS on-orbit operation and calibration activities implemented from launch to present and the status of instrument health and functions. It demonstrates sensor on-orbit performance derived from its telemetry, on-board calibrators (OBC), and lunar observations. Also discussed in this paper are changes in sensor characteristics, corrections applied to maintain level 1B data quality, various challenging issues, and future improvements.

  16. Marine oil pollution detection with MODIS data

    Science.gov (United States)

    Xu, Lina; Niu, Ruiqing; Xiao, Kang; Fang, Shenghui; Dong, Yanfang

    2013-10-01

    Marine oil pollution is one of the most serious pollutants on the damage to the contemporary marine environment, with the characteristics of a wide range of proliferation, which is difficult to control and eliminate. As a result, marine oil pollution has caused huge economic losses. The remote sensing sensors can detect and record the spectral information of sea film and background seawater. Here we chose to use 250-resolution MODIS data in the area of Dalian Xingang, China where ill spill case was happened on April.4th, 2005. Based on the image pre-processing and enhanced image processing, the spectral features of different bands were analyzed. More obvious characteristics of the spectral range of film was obtained. The oil-water contrast was calculated to evaluate the feature of oil at different spectral band. The result indicates that IR band has the maximum value of reflective. So band ratio was used between 400nm and 800nm and the original radiance images were used between 800nm and 2130nm. In order to get the most obvious images of entropy windows of different sizes were tested in order to decide the optimum window. At last, a FCM fuzzy clustering method and image texture analysis was combined for the MODIS images of the oil spill area segmentation. At last, the oil spill zone was estimated, the results were satisfied.

  17. Land Cover Classification of Landsat Data with Phenological Features Extracted from Time Series MODIS NDVI Data

    OpenAIRE

    Kun Jia; Shunlin Liang; Xiangqin Wei; Yunjun Yao; Yingru Su; Bo Jiang; Xiaoxia Wang

    2014-01-01

    Temporal-related features are important for improving land cover classification accuracy using remote sensing data. This study investigated the efficacy of phenological features extracted from time series MODIS Normalized Difference Vegetation Index (NDVI) data in improving the land cover classification accuracy of Landsat data. The MODIS NDVI data were first fused with Landsat data via the Spatial and Temporal Adaptive Reflectance Fusion Model (STARFM) algorithm to obtain NDVI data at the La...

  18. Multi-Angle Implementation of Atmospheric Correction for MODIS (MAIAC). Part 3: Atmospheric Correction

    Science.gov (United States)

    Lyapustin, A.; Wang, Y.; Laszlo, I.; Hilker, T.; Hall, F.; Sellers, P.; Tucker, J.; Korkin, S.

    2012-01-01

    This paper describes the atmospheric correction (AC) component of the Multi-Angle Implementation of Atmospheric Correction algorithm (MAIAC) which introduces a new way to compute parameters of the Ross-Thick Li-Sparse (RTLS) Bi-directional reflectance distribution function (BRDF), spectral surface albedo and bidirectional reflectance factors (BRF) from satellite measurements obtained by the Moderate Resolution Imaging Spectroradiometer (MODIS). MAIAC uses a time series and spatial analysis for cloud detection, aerosol retrievals and atmospheric correction. It implements a moving window of up to 16 days of MODIS data gridded to 1 km resolution in a selected projection. The RTLS parameters are computed directly by fitting the cloud-free MODIS top of atmosphere (TOA) reflectance data stored in the processing queue. The RTLS retrieval is applied when the land surface is stable or changes slowly. In case of rapid or large magnitude change (as for instance caused by disturbance), MAIAC follows the MODIS operational BRDF/albedo algorithm and uses a scaling approach where the BRDF shape is assumed stable but its magnitude is adjusted based on the latest single measurement. To assess the stability of the surface, MAIAC features a change detection algorithm which analyzes relative change of reflectance in the Red and NIR bands during the accumulation period. To adjust for the reflectance variability with the sun-observer geometry and allow comparison among different days (view geometries), the BRFs are normalized to the fixed view geometry using the RTLS model. An empirical analysis of MODIS data suggests that the RTLS inversion remains robust when the relative change of geometry-normalized reflectance stays below 15%. This first of two papers introduces the algorithm, a second, companion paper illustrates its potential by analyzing MODIS data over a tropical rainforest and assessing errors and uncertainties of MAIAC compared to conventional MODIS products.

  19. 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.

  20. Analysis of MODIS snow cover time series over the alpine regions as input for hydrological modeling

    Science.gov (United States)

    Notarnicola, Claudia; Rastner, Philipp; Irsara, Luca; Moelg, Nico; Bertoldi, Giacomo; Dalla Chiesa, Stefano; Endrizzi, Stefano; Zebisch, Marc

    2010-05-01

    Snow extent and relative physical properties are key parameters in hydrology, weather forecast and hazard warning as well as in climatological models. Satellite sensors offer a unique advantage in monitoring snow cover due to their temporal and spatial synoptic view. The Moderate Resolution Imaging Spectrometer (MODIS) from NASA is especially useful for this purpose due to its high frequency. However, in order to evaluate the role of snow on the water cycle of a catchment such as runoff generation due to snowmelt, remote sensing data need to be assimilated in hydrological models. This study presents a comparison on a multi-temporal basis between snow cover data derived from (1) MODIS images, (2) LANDSAT images, and (3) predictions by the hydrological model GEOtop [1,3]. The test area is located in the catchment of the Matscher Valley (South Tyrol, Northern Italy). The snow cover maps derived from MODIS-images are obtained using a newly developed algorithm taking into account the specific requirements of mountain regions with a focus on the Alps [2]. This algorithm requires the standard MODIS-products MOD09 and MOD02 as input data and generates snow cover maps at a spatial resolution of 250 m. The final output is a combination of MODIS AQUA and MODIS TERRA snow cover maps, thus reducing the presence of cloudy pixels and no-data-values due to topography. By using these maps, daily time series starting from the winter season (November - May) 2002 till 2008/2009 have been created. Along with snow maps from MODIS images, also some snow cover maps derived from LANDSAT images have been used. Due to their high resolution (Schellenberger T., Della Chiesa S., Bertoldi G., Endrizzi S., Notarnicola C., Steurer C., Zebisch M. 2009. Monitoraggio del manto nevoso in aree alpine con dati MODIS multi-temporali e modelli idrologici, 13th ASITA National Conference, 1-4.12.2009, Bari, Italy. [3] Zanotti F., Endrizzi S., Bertoldi G. and Rigon R. 2004. The GEOtop snow module

  1. 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...

  2. 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.

  3. 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.

  4. 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

  5. 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.

  6. 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.

  7. 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.

  8. Validation and Uncertainty Estimates for MODIS Collection 6 "Deep Blue" Aerosol Data

    Science.gov (United States)

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

    2013-01-01

    The "Deep Blue" aerosol optical depth (AOD) retrieval algorithm was introduced in Collection 5 of the Moderate Resolution Imaging Spectroradiometer (MODIS) product suite, and complemented the existing "Dark Target" land and ocean algorithms by retrieving AOD over bright arid land surfaces, such as deserts. The forthcoming Collection 6 of MODIS products will include a "second generation" Deep Blue algorithm, expanding coverage to all cloud-free and snow-free land surfaces. The Deep Blue dataset will also provide an estimate of the absolute uncertainty on AOD at 550 nm for each retrieval. This study describes the validation of Deep Blue Collection 6 AOD at 550 nm (Tau(sub M)) from MODIS Aqua against Aerosol Robotic Network (AERONET) data from 60 sites to quantify these uncertainties. The highest quality (denoted quality assurance flag value 3) data are shown to have an absolute uncertainty of approximately (0.086+0.56Tau(sub M))/AMF, where AMF is the geometric air mass factor. For a typical AMF of 2.8, this is approximately 0.03+0.20Tau(sub M), comparable in quality to other satellite AOD datasets. Regional variability of retrieval performance and comparisons against Collection 5 results are also discussed.

  9. 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.

  10. 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.

  11. 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.

  12. 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

  13. 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

  14. 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

  15. 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...... eight different families. BMI-matched T2D and healthy subjects were used as two separate control groups. The early phase of insulin secretion was attenuated in HNF4A, HNF1A MODY and T2D (AUC0-30 controls: 558.2 ± 101.2, HNF4A MODY: 93.8 ± 57.0, HNF1A MODY: 170.2 ± 64.5, T2D: 211.2 ± 65.3, P <0.......01). Markedly reduced levels of proinsulin were found in HNF4A MODY compared to T2D and that tended to be so also in HNF1A MODY (HNF4A MODY: 3.7 ± 1.2, HNF1A MODY: 8.3 ± 3.8 vs. T2D: 26.6 ± 14.3). Patients with HNF4A MODY had similar total GLP-1 and GIP responses as controls (GLP-1 AUC: (control: 823.9 ± 703...

  16. 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.

  17. 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

  18. 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.

  19. 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.

  20. 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

  1. 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...

  2. MODIS-Based Mapping of Secchi Disk Depth Using a Qualitative Algorithm in the Shallow Arabian Gulf

    Directory of Open Access Journals (Sweden)

    Muna. R. Al Kaabi

    2016-05-01

    Full Text Available Regionally calibrated algorithms for water quality are strongly needed, especially for optically complex waters such as coastal areas in the Arabian Gulf. In this study, a regional qualitative algorithm was proposed to retrieve seawater transparency, with Secchi disk depth (SDD as a surrogate, in the Arabian Gulf. A two-step process was carried out, first estimating the diffuse attenuation coefficient of downwelling irradiance at 490 nm (Kd_490 from MODIS/Aqua imagery and then SDD based on empirical correlations with Kd_490. Three satellite derived Kd products were tested and assessed against a set of in situ measurements, and one from a semi-analytical algorithm based on inherent optical properties gave the best performance with a R2 of 0.62. Comparisons between the performances of SDD models developed in this study and those established in other regions indicated higher accuracy of our proposed model for the Gulf region. The potential factors causing uncertainties of the proposed algorithm were also discussed. Seasonal and inter-annual variations of SDD over the entire Gulf were demonstrated using a 14-year time series of MODIS/Aqua data from 2002 to 2015. High SDD values were generally observed in summer while low values were found in winter. Inter-annual variations of SDD did not shown any significant trend with exceptions during algal bloom outbreaks that resulted in low SDD.

  3. 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

  4. 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

  5. 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

  6. 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

  7. 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.

  8. 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

  9. 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

  10. 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.

  11. 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.

  12. 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.

  13. 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...

  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 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...

  16. 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.

    . (2000) Chl_a¼ 10ðaþbRþcR2þdR5þeR4 Þ R¼ log10 max Rrs443 Rrs547 � � ; Rrs488 Rrs547 ��� a¼0.2424; b¼−2.7423; c¼1.8017; GSM Maritorena et al. (2002) LwNðλÞ ¼ tF0 ðλÞn2w ∑ 2 i ¼ 1gi ½bbw ðλÞþbbpð443Þðλ � GIOP Franz and Werdell (2010) rrsðλ;0−Þ ¼ Rrs ðλÞ0... (Sdg), particle-specific backscattering coefficient (bbpn), back- scattering coefficient slope (Sbp) which are taken from the GSM model (Franz and Werdell, 2010).Chla algorithms were compared.TSM (g m-3) 0 10 20 30 40 50 60 0.0 0.2 Fig. 2. Scatter plots...

  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. 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.

  20. 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...

  1. 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.

  2. 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...

  3. Spatio-temporal dynamics of phytoplankton and primary production in Lake Tanganyika using a MODIS based bio-optical time series

    DEFF Research Database (Denmark)

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

    2010-01-01

    Lake Tanganyika, the second largest freshwater ecosystem in Africa, is characterised by a significant heterogeneity in phytoplankton concentration linked to its particular hydrodynamics. To gather a proper understanding of primary production, it is necessary to consider spatial and temporal...... dynamics throughout the lake. In the present work, daily MODIS-AQUA satellite measurements were used to estimate chlorophyll-a concentrations and the diffuse attenuation coefficient (K490) for surface waters. The spatial regionalisation of Lake Tanganyika, based on Empirical Orthogonal Functions of the...

  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. 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.

  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. 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.

  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. 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...

  11. 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.

  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. 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

  15. 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.

  16. Daily MODIS Data Trends of Hurricane-Induced Forest Impact and Early Recovery

    Science.gov (United States)

    Ramsey, Elijah, 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 prehurricane 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.

  17. ELABORATION OF NOT LARGE MOBILE MODULAR INSTALLATION ''AQUA - EXPRESS'' (300 L/H) FOR LRW CLEANING

    International Nuclear Information System (INIS)

    Mobile modular installation ''Aqua-Express'' is a liquid low level and intermediate level radioactive waste (LL and ILRW) treatment facility, intended for not large research centers and other organizations, which activity causes the formation of a few quantity (up to 500 m3/year) of low and intermediate level radioactive waste water. Mobile modular installation ''Aqua-Express'' has the following features: (1) filtration, sorption and ultrafiltration units are used for LL and ILRW purification; (2) installation ''Aqua-Express'' consists of a cascade of three autonomous aqueous liquid waste-purifying installations; (3) installation ''Aqua-Express'' is a mobile installation; the installation can be transported by car, train, ship, or plane, as well as placed in a standard transport (sea or railway) container; (4) installation ''Aqua-Express'' does not includes any technological equipment for conditioning the secondary radioactive waste. Productivity of the installation ''Aqua-Express'' by purified water depends on composition of the initial liquid waste and makes up to 300 l/h. In present report is described the design of installation ''Aqua-Express'', theory of LRW purification in the installation ''Aqua-Express'' and some results of its use at cleaning real radioactive waters at State unitary enterprise - MosNPO ''Radon''

  18. 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 ...

  19. Quantitative Evaluation of MODIS Fire Radiative Power Measurement for Global Smoke Emissions Assessment

    Science.gov (United States)

    Ichoku, Charles; Ellison, Luke

    2011-01-01

    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 steadily gained increasing recognition as an important parameter for facilitating the development of various scientific studies and applications relating to the quantitative characterization of biomass burning and their emissions. To establish the scientific integrity of the FRP as a stable quantity that can be measured consistently across a variety of sensors and platforms, with the potential of being utilized to develop a unified long-term climate data record of fire activity and impacts, it needs to be thoroughly evaluated, calibrated, and validated. Therefore, we are conducting a detailed analysis of the FRP products from MODIS to evaluate the uncertainties associated with them, such as those due to the effects of satellite variable observation geometry and other factors, in order to establish their error budget for use in diverse scientific research and applications. In this presentation, we will show recent results of the MODIS FRP uncertainty analysis and error mitigation solutions, and demonstrate

  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. 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

  2. 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.

  3. 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.

  4. 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

  5. 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...

  6. 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

  7. 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.

  8. 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.

  9. Reflecting Reflective Practice

    Science.gov (United States)

    Galea, Simone

    2012-01-01

    This paper demystifies reflective practice on teaching by focusing on the idea of reflection itself and how it has been conceived by two philosophers, Plato and Irigaray. It argues that reflective practice has become a standardized method of defining the teacher in teacher education and teacher accreditation systems. It explores how practices of…

  10. Implementation of electronic crosstalk correction for terra MODIS PV LWIR bands

    Science.gov (United States)

    Geng, Xu; Madhavan, Sriharsha; Chen, Na; Xiong, Xiaoxiong

    2015-09-01

    The MODerate-resolution Imaging Spectroradiometer (MODIS) is one of the primary instruments in the fleet of NASA's Earth Observing Systems (EOS) in space. Terra MODIS has completed 15 years of operation far exceeding its design lifetime of 6 years. The MODIS Level 1B (L1B) processing is the first in the process chain for deriving various higher level science products. These products are used mainly in understanding the geophysical changes occurring in the Earth's land, ocean, and atmosphere. The L1B code is designed to carefully calibrate the responses of all the detectors of the 36 spectral bands of MODIS and provide accurate L1B radiances (also reflectances in the case of Reflective Solar Bands). To fulfill this purpose, Look Up Tables (LUTs), that contain calibration coefficients derived from both on-board calibrators and Earth-view characterized responses, are used in the L1B processing. In this paper, we present the implementation mechanism of the electronic crosstalk correction in the Photo Voltaic (PV) Long Wave InfraRed (LWIR) bands (Bands 27-30). The crosstalk correction involves two vital components. First, a crosstalk correction modular is implemented in the L1B code to correct the on-board Blackbody and Earth-View (EV) digital number (dn) responses using a linear correction model. Second, the correction coefficients, derived from the EV observations, are supplied in the form of LUTs. Further, the LUTs contain time stamps reflecting to the change in the coefficients assessed using the Noise Equivalent difference Temperature (NEdT) trending. With the algorithms applied in the MODIS L1B processing it is demonstrated that these corrections indeed restore the radiometric balance for each of the affected bands and substantially reduce the striping noise in the processed images.

  11. 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

  12. Reflecting reflection in supervision

    DEFF Research Database (Denmark)

    Lystbæk, Christian Tang

    Reflection has moved from the margins to the mainstream in supervision. Notions of reflection have become well established since the late 1980s. These notions have provided useful framing devices to help conceptualize some important processes in guidance and counseling. However, some applications...... previously associated with reflection and an exploration of alternative conceptions that view reflection within the context of settings which have a more group- and team-based orientation. Drawing on an action research project on health care supervision, the paper questions whether we should reject earlier...... views of reflection, rehabilitate them in order to capture broader connotations or move to new ways of regarding reflection that are more in keeping with not only reflective but also emotive, normative and formative views on supervision. The paper presents a critical perspective on supervision that...

  13. Poly[[μ-aqua-aqua[μ4-ethyl (dichloromethylenediphosphonato]sesquicalcium(II] acetone hemisolvate 4.5-hydrate

    Directory of Open Access Journals (Sweden)

    Jonna Jokiniemi

    2009-04-01

    Full Text Available The title compound, {[Ca1.5(C3H5Cl2O6P2(H2O2]·0.5CH3COCH3·4.5H2O}n, has a two-dimensional polymeric structure. The asymmetric unit contains two crystallographically independent Ca2+ cations connected by a chelating and bridging ethyl (dichloromethylenediphosphonate(3− ligand and an aqua ligand. One of the Ca atoms, lying on a centre of symmetry, has a slightly distorted octahedral geometry, while the other Ca atom is seven-coordinated in a distorted monocapped trigonal-prismatic geometry. The polymeric layers are further connected by extensive O—H...O hydrogen bonding into a three-dimensional supramolecular network. The acetone solvent molecule and one uncoordinated water molecule are located on twofold rotation axes.

  14. Frost Monitoring and Forecasting Using MODIS Land Surface Temperature Data and a Numerical Weather Prediction Model Forecasts for Eastern Africa

    Science.gov (United States)

    Kabuchanga, Eric; Flores, Africa; Malaso, Susan; Mungai, John; Sakwa, Vincent; Shaka, Ayub; Limaye, Ashutosh

    2014-01-01

    Frost is a major challenge across Eastern Africa, severely impacting agricultural farms. Frost damages have wide ranging economic implications on tea and coffee farms, which represent a major economic sector. Early monitoring and forecasting will enable farmers to take preventive actions to minimize the losses. Although clearly important, timely information on when to protect crops from freezing is relatively limited. MODIS Land Surface Temperature (LST) data, derived from NASA's Terra and Aqua satellites, and 72-hr weather forecasts from the Kenya Meteorological Service's operational Weather Research Forecast model are enabling the Regional Center for Mapping of Resources for Development (RCMRD) and the Tea Research Foundation of Kenya to provide timely information to farmers in the region. This presentation will highlight an ongoing collaboration among the Kenya Meteorological Service, RCMRD, and the Tea Research Foundation of Kenya to identify frost events and provide farmers with potential frost forecasts in Eastern Africa.

  15. Characterization of MODIS Solar Diffuser On-Orbit Degradation

    Science.gov (United States)

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

    2010-01-01

    MODIS reflective solar bands (RSB) are calibrated using a solar diffuser (SD). The SD on-orbit degradation is determined by a solar diffuser stability monitor (SDSM) at 9 wavelengths from 0.41 to 0.94 microns via alternate observations of its sunlight reflected from the SD (SD view) and direct sunlight through an attenuation screen (Sun view). For each SDSM detector, a time series of ratios of its SD view to its Sun view responses tracks on-orbit changes in the SD bidirectional reflectance factor (BRF) at its wavelength. Due to an SDSM component design error, however, there exist large ripples in its Sun view responses, which have made it extremely difficult to use the original ratio approach for accurate characterization of SD on-orbit degradation. In order to mitigate the impact due to unexpected ripples, MODIS Characterization Support Team (MCST) developed a normalization approach. It relies on the fact that all SDSM detectors (D1 to D9) experience similar ripples and assumes that the SD degradation at its D9 wavelength (0.94 micron) is extremely small and can be ignored. As mission continues, the normalization approach becomes inadequate since the accumulated SD degradation at 0.94[tm can no longer be ignored. This paper presents a new approach to further improve on-orbit characterization of SD degradation. It uses a took-up table (LUT) with parameters derived from D9 observations made over a short period. Compared to other approaches, this approach can significantly reduce the impact due to ripples and that due to accumulated SD degradation at the reference detector wavelength.

  16. Improved Topographic Normalization for Landsat TM Images by Introducing the MODIS Surface BRDF

    Directory of Open Access Journals (Sweden)

    Yanli Zhang

    2015-05-01

    Full Text Available 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 pixel reflectance into a flat pixel reflectance by using the Ross Thick-Li Sparse BRDF model (Ambrals algorithm and MODIS BRDF/albedo kernel coefficient products. Sole atmospheric correction and topographic normalization were performed for TM images in the upper stream of the Heihe River Basin. The results show that using MODIS atmospheric products can effectively remove atmospheric effects compared with the Fast Line-of-Sight Atmospheric Analysis of Spectral Hypercubes (FLAASH model and the Landsat Climate Data Record (CDR. Moreover, superior topographic effect removal can be achieved by considering the surface BRDF when compared with the surface Lambertian assumption of topographic normalization.

  17. Retrieval of snow Specific Surface Area (SSA) from MODIS data in mountainous regions

    Science.gov (United States)

    Mary, A.; Dumont, M.; Dedieu, J.-P.; Durand, Y.; Sirguey, P.; Milhem, H.; Mestre, O.; Negi, H. S.; Kokhanovsky, A. A.

    2012-05-01

    This study describes a method to retrieve snow specific surface area (SSA) from satellite radiance reasurements in mountainous terrain. It aims at comparing different retrieval methods and at addressing topographic corrections of reflectance, namely slope and aspect of terrain and multiple reflections on neighbouring slopes. We use an iterative algorithm to compute reflectance from radiance of the MODerate resolution Imaging Spectrometer (MODIS) with a comprehensive correction of local illumination with regards to topography. The retrieved SSA is compared to the results of the snowpack model Crocus, fed by driving data from the SAFRAN meteorological analysis, over a large domain in the French Alps. We compared SSA retrievals with and without topographic or anisotropy correction, and with a spherical or non-spherical snow reflectance model. The topographic correction enables SSA to be retrieved in better agreement with those from SAFRAN-Crocus. The root mean square deviation is 10.0 m2 kg-1 and the bias is -0.6 m2 kg-1, over 3829 pixels representing seven different dates and snow conditions. The standard deviation of MODIS retrieved data, larger than the one of SAFRAN-Crocus estimates, is responsible for half this RMSD. It is due to the topographic classes used by SAFRAN-Crocus. In addition, MODIS retrieved data show SSA gradients with elevation and solar exposition, physically consistent and in good agreement with SAFRAN-Crocus.

  18. Retrieval of snow Specific Surface Area (SSA from MODIS data in mountainous regions

    Directory of Open Access Journals (Sweden)

    A. Mary

    2012-05-01

    Full Text Available This study describes a method to retrieve snow specific surface area (SSA from satellite radiance reasurements in mountainous terrain. It aims at comparing different retrieval methods and at addressing topographic corrections of reflectance, namely slope and aspect of terrain and multiple reflections on neighbouring slopes. We use an iterative algorithm to compute reflectance from radiance of the MODerate resolution Imaging Spectrometer (MODIS with a comprehensive correction of local illumination with regards to topography. The retrieved SSA is compared to the results of the snowpack model Crocus, fed by driving data from the SAFRAN meteorological analysis, over a large domain in the French Alps. We compared SSA retrievals with and without topographic or anisotropy correction, and with a spherical or non-spherical snow reflectance model. The topographic correction enables SSA to be retrieved in better agreement with those from SAFRAN-Crocus. The root mean square deviation is 10.0 m2 kg−1 and the bias is −0.6 m2 kg−1, over 3829 pixels representing seven different dates and snow conditions. The standard deviation of MODIS retrieved data, larger than the one of SAFRAN-Crocus estimates, is responsible for half this RMSD. It is due to the topographic classes used by SAFRAN-Crocus. In addition, MODIS retrieved data show SSA gradients with elevation and solar exposition, physically consistent and in good agreement with SAFRAN-Crocus.

  19. A Simple Technique for Creating Regional Composites of Sea Surface Temperature from MODIS for Use in Operational Mesoscale NWP

    Science.gov (United States)

    Knievel, Jason C.; Rife, Daran L.; Grim, Joseph A.; Hahmann, Andrea N.; Hacker, Joshua P.; Ge, Ming; Fisher, Henry H.

    2010-01-01

    This paper describes a simple technique for creating regional, high-resolution, daytime and nighttime composites of sea surface temperature (SST) for use in operational numerical weather prediction (NWP). The composites are based on observations from NASA s Moderate Resolution Imaging Spectroradiometer (MODIS) aboard Aqua and Terra. The data used typically are available nearly in real time, are applicable anywhere on the globe, and are capable of roughly representing the diurnal cycle in SST. The composites resolution is much higher than that of many other standard SST products used for operational NWP, including the low- and high-resolution Real-Time Global (RTG) analyses. The difference in resolution is key because several studies have shown that highly resolved SSTs are important for driving the air sea interactions that shape patterns of static stability, vertical and horizontal wind shear, and divergence in the planetary boundary layer. The MODIS-based composites are compared to in situ observations from buoys and other platforms operated by the National Data Buoy Center (NDBC) off the coasts of New England, the mid-Atlantic, and Florida. Mean differences, mean absolute differences, and root-mean-square differences between the composites and the NDBC observations are all within tenths of a degree of those calculated between RTG analyses and the NDBC observations. This is true whether or not one accounts for the mean offset between the skin temperatures of the MODIS dataset and the bulk temperatures of the NDBC observations and RTG analyses. Near the coast, the MODIS-based composites tend to agree more with NDBC observations than do the RTG analyses. The opposite is true away from the coast. All of these differences in point-wise comparisons among the SST datasets are small compared to the 61.08C accuracy of the NDBC SST sensors. Because skin-temperature variations from land to water so strongly affect the development and life cycle of the sea breeze, this

  20. Analyzing the anisotropy of thermal infrared emissivity over arid regions using a new MODIS land surface temperature and emissivity product (MOD21)

    OpenAIRE

    García Santos, Vicente; Coll Company, César; Valori Micó, Enric; Niclòs Corts, Raquel; Caselles Miralles, Vicente

    2015-01-01

    The MOD21 Land Surface Temperature and Emissivity (LST&E) product will be included in forthcoming Moderate Resolution Imaging Spectroradiometer (MODIS) Collection 6. Surface temperature and emissivities for thermal bands 29 (8.55 μm), 31 (11 μm) and 32 (12 μm) will be retrieved using the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) Temperature and Emissivity Separation (TES) method adapted to MODIS at-sensor spectral radiances, previously corrected with the Water Vap...

  1. Land Surface Microwave Emissivities Derived from AMSR-E and MODIS Measurements with Advanced Quality Control

    Science.gov (United States)

    Moncet, Jean-Luc; Liang, Pan; Galantowicz, John F.; Lipton, Alan E.; Uymin, Gennady; Prigent, Catherine; Grassotti, Christopher

    2011-01-01

    A microwave emissivity database has been developed with data from the Advanced Microwave Scanning Radiometer-EOS (AMSR-E) and with ancillary land surface temperature (LST) data from the Moderate Resolution Imaging Spectroradiometer (MODIS) on the same Aqua spacecraft. The primary intended application of the database is to provide surface emissivity constraints in atmospheric and surface property retrieval or assimilation. An additional application is to serve as a dynamic indicator of land surface properties relevant to climate change monitoring. The precision of the emissivity data is estimated to be significantly better than in prior databases from other sensors due to the precise collocation with high-quality MODIS LST data and due to the quality control features of our data analysis system. The accuracy of the emissivities in deserts and semi-arid regions is enhanced by applying, in those regions, a version of the emissivity retrieval algorithm that accounts for the penetration of microwave radiation through dry soil with diurnally varying vertical temperature gradients. These results suggest that this penetration effect is more widespread and more significant to interpretation of passive microwave measurements than had been previously established. Emissivity coverage in areas where persistent cloudiness interferes with the availability of MODIS LST data is achieved using a classification-based method to spread emissivity data from less-cloudy areas that have similar microwave surface properties. Evaluations and analyses of the emissivity products over homogeneous snow-free areas are presented, including application to retrieval of soil temperature profiles. Spatial inhomogeneities are the largest in the vicinity of large water bodies due to the large water/land emissivity contrast and give rise to large apparent temporal variability in the retrieved emissivities when satellite footprint locations vary over time. This issue will be dealt with in the future by

  2. Monitoring ice break-up on the Mackenzie River using MODIS data

    Science.gov (United States)

    Muhammad, P.; Duguay, C.; Kang, K.-K.

    2016-03-01

    The aim of this study was to develop an approach for estimating ice break-up dates on the Mackenzie River (MR) using more than a decade of MODIS Level 3 500 m snow products (MOD/MYD10A1), complemented with 250 m Level 1B radiance products (MOD/MYD02QKM) from the Terra and Aqua satellite platforms. The analysis showed break-up began on average between days of year (DOYs) 115 and 125 and ended between DOYs 145 and 155 over 13 ice seasons (2001-2013), resulting in an average melt duration of ca. 30-40 days. Thermal processes were more important in driving ice break-up south of the MR confluence with the Liard River, while dynamically driven break-up was more important north of the Liard. A comparison of the timing of ice disappearance with snow disappearance from surrounding land areas of the MR with MODIS Level 3 snow products showed varying relationships along the river. Ice-off and snow-off timing were in sync north of the MR-Liard River confluence and over sections of the MR before it enters the Mackenzie Delta, but ice disappeared much later than snow on land in regions where thermal ice break-up processes dominated. MODIS observations revealed that channel morphology is a more important control of ice break-up patterns than previously believed with ice runs on the MR strongly influenced by channel morphology (islands and bars, confluences and channel constriction). Ice velocity estimates from feature tracking were able to be made in 2008 and 2010 and yielded 3-4-day average ice velocities of 1.21 and 1.84 m s-1 respectively, which is in agreement with estimates from previous studies. These preliminary results confirm the utility of daily MODIS data for monitoring ice break-up processes along the Mackenzie River. The addition of optical and synthetic aperture radar data from recent and upcoming satellite missions (e.g. Sentinel-1/2/3 and RADARSAT Constellation) would improve the monitoring of ice break-up in narrower sections of the MR.

  3. Reflecting on Cherenkov reflections

    OpenAIRE

    Fargion, D.; Gaug, M.; Oliva, P.

    2007-01-01

    Magic Telescope may observe and reveal at horizons lights from air-shower Cherenkov reflections. The ground, the sea, the cloudy sky (below the mountain) may reflect PeVs-EeV UHECR Cherenkov lights observable by MAGIC telescopes. Even rarest UHE neutrino skimming the atmosphere or skimming the Earth may induce upward-horizontal airshowers: a new Neutrino Astronomy. These fluorescence signals or the Cherenkov reflections in upper cloudy sky may flash in correlated BL-Lac or GRB shining at oppo...

  4. Large scale maps of cropping intensity in Asia from MODIS

    Science.gov (United States)

    Gray, J. M.; Friedl, M. A.; Frolking, S. E.; Ramankutty, N.; Nelson, A.

    2013-12-01

    Agricultural systems are geographically extensive, have profound significance to society, and also affect regional energy, carbon, and water cycles. Since most suitable lands worldwide have been cultivated, there is growing pressure to increase yields on existing agricultural lands. In tropical and sub-tropical regions, multi-cropping is widely used to increase food production, but regional-to-global information related to multi-cropping practices is poor. Such information is of critical importance to ensure sustainable food production while mitigating against negative environmental impacts associated with agriculture such as contamination and depletion of freshwater resources. Unfortunately, currently available large-area inventory statistics are inadequate because they do not capture important spatial patterns in multi-cropping, and are generally not available in a timeframe that can be used to help manage cropping systems. High temporal resolution sensors such as MODIS provide an excellent source of information for addressing this need. However, relative to studies that document agricultural extensification, systematic assessment of agricultural intensification via multi-cropping has received relatively little attention. The goal of this work is to help close this methodological and information gap by developing methods that use multi-temporal remote sensing to map multi-cropping systems in Asia. Image time series analysis is especially challenging in Asia because atmospheric conditions including clouds and aerosols lead to high frequencies of missing or low quality remote sensing observations, especially during the Asian Monsoon. The methodology that we use for this work builds upon the algorithm used to produce the MODIS Land Cover Dynamics product (MCD12Q2), but employs refined methods to segment, smooth, and gap-fill 8-day EVI time series calculated from MODIS BRDF corrected surface reflectances. Crop cycle segments are identified based on changes in slope

  5. Application of MODIS GPP to Forecast Risk of Hantavirus Pulmonary Syndrome Based on Fluctuations in Reservoir Population Density

    Science.gov (United States)

    Loehman, R.; Heinsch, F. A.; Mills, J. N.; Wagoner, K.; Running, S.

    2003-12-01

    Recent predictive models for hantavirus pulmonary syndrome (HPS) have used remotely sensed spectral reflectance data to characterize risk areas with limited success. We present an alternative method using gross primary production (GPP) from the MODIS sensor to estimate the effects of biomass accumulation on population density of Peromyscus maniculatus (deer mouse), the principal reservoir species for Sin Nombre virus (SNV). The majority of diagnosed HPS cases in North America are attributed to SNV, which is transmitted to humans through inhalation of excretions and secretions from infected rodents. A logistic model framework is used to evaluate MODIS GPP, temperature, and precipitation as predictors of P. maniculatus density at established trapping sites across the western United States. Rodent populations are estimated using monthly minimum number alive (MNA) data for 2000 through 2002. Both local meteorological data from nearby weather stations and 1.25 degree x 1 degree gridded data from the NASA DAO were used in the regression model to determine the spatial sensitivity of the response. MODIS eight-day GPP data (1-km resolution) were acquired and binned to monthly average and monthly sum GPP for 3km x 3km grids surrounding each rodent trapping site. The use of MODIS GPP to forecast HPS risk may result in a marked improvement over past reflectance-based risk area characterizations. The MODIS GPP product provides a vegetation dynamics estimate that is unique to disease models, and targets the fundamental ecological processes responsible for increased rodent density and amplified disease risk.

  6. Ice Coverage, Aqua AMSR-E, 0.125 degrees, Global, Near Real Time

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Ice Coverage is measured by the Advanced Microwave Scanning Radiometer for the Earth Observing System (AMSR-E) onboard NASA's Aqua spacecraft.

  7. AIRS/Aqua Level 1B HSB geolocated and calibrated brightness temperatures 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...

  8. A simple digestion method with a Lefort aqua regia solution for diatom extraction.

    Science.gov (United States)

    Wang, Huipin; Liu, Yan; Zhao, Jian; Hu, Sunlin; Wang, Yuzhong; Liu, Chao; Zhang, Yanji

    2015-01-01

    Presence of diatoms in tissues has been considered as a significant sign of drowning. However, there are limitations in the present extraction methods. We developed a new digestion method using the Lefort aqua regia solution (3:1 nitric acid to hydrochloric acid) for diatom extraction and evaluated the digestive capability, diatom destruction, and diatoms' recovery of this new method. The kidney tissues from rabbit mixed with water rich in diatoms were treated by the Lefort aqua regia digestion method (n = 10) and the conventional acid digestion method (n = 10). The results showed that the digestive capability of Lefort aqua regia digestion method was superior to conventional acid digestion method (p 0.05). The Lefort aqua regia reagent is an improvement over the conventional acid digestion for recovery of diatoms from tissue samples. PMID:25399968

  9. 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

    Satellite sensor-derived data are suitable for regional estimations of several important biophysical variables. Data with a finer spatial resolution should improve regional estimations of GPP (gross primary productivity), since they better capture the variation in a heterogeneous landscape. The...... temperature) (R2=0.55–0.81, 0.57–0.77) and between GPP and EVI2, PPFD and daytime LST in multiple linear regressions (R2=0.73–0.89, 0.65–0.93). One year of data was collected from all coniferous sites to derive a general empirical model for GPP versus (1) the product of EVI2 and PPFD (R2=0.70), (2) 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...

  10. Global Aerosol Optical Models and Lookup Tables for the New MODIS Aerosol Retrieval over Land

    Science.gov (United States)

    Levy, Robert C.; Remer, Loraine A.; Dubovik, Oleg

    2007-01-01

    Since 2000, MODIS has been deriving aerosol properties over land from MODIS observed spectral reflectance, by matching the observed reflectance with that simulated for selected aerosol optical models, aerosol loadings, wavelengths and geometrical conditions (that are contained in a lookup table or 'LUT'). Validation exercises have showed that MODIS tends to under-predict aerosol optical depth (tau) in cases of large tau (tau greater than 1.0), signaling errors in the assumed aerosol optical properties. Using the climatology of almucantur retrievals from the hundreds of global AERONET sunphotometer sites, we found that three spherical-derived models (describing fine-sized dominated aerosol), and one spheroid-derived model (describing coarse-sized dominated aerosol, presumably dust) generally described the range of observed global aerosol properties. The fine dominated models were separated mainly by their single scattering albedo (omega(sub 0)), ranging from non-absorbing aerosol (omega(sub 0) approx. 0.95) in developed urban/industrial regions, to neutrally absorbing aerosol (omega(sub 0) approx.90) in forest fire burning and developing industrial regions, to absorbing aerosol (omega(sub 0) approx. 0.85) in regions of savanna/grassland burning. We determined the dominant model type in each region and season, to create a 1 deg. x 1 deg. grid of assumed aerosol type. We used vector radiative transfer code to create a new LUT, simulating the four aerosol models, in four MODIS channels. Independent AERONET observations of spectral tau agree with the new models, indicating that the new models are suitable for use by the MODIS aerosol retrieval.

  11. Assessment of MODIS BRDF shape indicators%评估MODIS的BRDF角度指数产品

    Institute of Scientific and Technical Information of China (English)

    焦子锑; 李小文; 王锦地; 张虎

    2011-01-01

    应用地表观测的二向性反射数据集和多种MODIS数据产品,通过统计分析,对MODIS的二向性反射角度指数产品进行综合评估,结果表明:(1)MODIS角度指数包含了地表三维结构信息,有望用来反演地表的物理结构参数;(2)MODIS角度指数是内在的三维关系,各向异性因子(Anisotropic Factor:ANIF)和各向异性指数(Anisotropic Index:ANIX)高相关,建议去掉ANIF以精炼MODIS角度指数产品;(3)各向异性平整指数(Anisotropic FlatIndex:AFX)较好地指示了地表基本散射类型的变化,且具有较小的类内方差,对改善特定地表分类精度可能会更有用.%Bidirectional Reflectance Distribution Function (BRDF) shape indicators of Moderate Resolution Imaging Spectroradiometer (MODIS) are among MODIS BRDF/Albedo products and are helpful in expanding the application of BRDF remote sensing data. This paper evaluates the MODIS BRDF shape indicators with the statistical analysis methods by using various collected ground BRDF datasets and MODIS products. Our result presents several major findings: (1) the MODIS BRDF shape indicators contain the information regarding 3-D structure of land surface and have the possibility to retrieve the structural parameters of the land surface; (2) the MODIS BRDF shape indicators are intrinsically three-dimensional. Since Anisotropic Index (ANIX) is highly related to Anisotropic Factor (ANIF) and has wider value range than the ANIF, the ANIF may be removed from the MODIS BRDF shape indicator products for refinement of the MODIS BRDF/Albedo products; (3) Anisotropic Flat Index (AFX) is related to basically scattering types of land surface with low within-class variances, so it is considered to be more useful in improving land cover classification accuracy.

  12. Land surface temperature inversion of bare soil and vegetation cover based on MODIS data

    Science.gov (United States)

    Li, Jingwen; Zhou, Song; Wang, Zhezhen; Lv, Nan; Jiang, Jianwu; Wang, Ke

    2015-12-01

    Land surface temperature is one of the most important parameters in hydrology and agricultural production research . Split-window algorithm based on MODIS data was briefly introduced in this paper and applied in Hetao Irrigation District. Comparison between data retrieval and field collected data showed that data retrieval could reflect land surface temperature basic accurately .Linear fitting of different time series data can improve retrieval precision effectively. The results provide support for drought forecast, soil moisture monitoring etc. in the future.

  13. A Novel Land Cover Classification Map Based on a MODIS Time-Series in Xinjiang, China

    OpenAIRE

    Linlin Lu; Claudia Kuenzer; Huadong Guo; Qingting Li; Tengfei Long; Xinwu Li

    2014-01-01

    Accurate mapping of land cover on a regional scale is useful for climate and environmental modeling. In this study, we present a novel land cover classification product based on spectral and phenological information for the Xinjiang Uygur Autonomous Region (XUAR) in China. The product is derived at a 500 m spatial resolution using an innovative approach employing moderate resolution imaging spectroradiometer (MODIS) surface reflectance and the enhanced vegetation index (EVI) time series. The ...

  14. Evaluation of Three MODIS-Derived Vegetation Index Time Series for Dryland Vegetation Dynamics Monitoring

    OpenAIRE

    Linlin Lu; Claudia Kuenzer; Cuizhen Wang; Huadong Guo; Qingting Li

    2015-01-01

    Understanding the spatial and temporal dynamics of vegetation is essential in drylands. In this paper, we evaluated three vegetation indices, namely the Normalized Difference Vegetation Index (NDVI), the Soil-Adjusted Vegetation Index (SAVI) and the Enhanced Vegetation Index (EVI), derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) Surface-Reflectance Product in the Xinjiang Uygur Autonomous Region, China (XUAR), to assess index time series’ suitability for monitoring vege...

  15. Reducing the Discrepancy Between ASTER and MODIS Land Surface Temperature Products

    OpenAIRE

    Changqing Ke; Yasushi Yamaguchi; Yuanbo Liu

    2007-01-01

    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,...

  16. Improving MODIS spatial resolution for snow mapping using wavelet fusion and ARSIS concept

    OpenAIRE

    Sirguey, Pascal; Mathieu, Renaud; Arnaud, Yves; Khan, Muhammad; Chanussot, Jocelyn

    2008-01-01

    We propose to fuse the high spatial content of two 250-m spectral bands of the Moderate Resolution Imaging Spectroradiometer (MODIS) into its five 500-m bands using wavelet-based multiresolution analysis. Our objective was to test the effectiveness of this technique to increase the accuracy of snow mapping in mountainous environments. To assess the performance of this approach, we took advantage of the simultaneity between the Advanced Spaceborne Thermal Emission and Reflection Radiometer (AS...

  17. MODIS NDVI Change Detection Techniques and Products Used in the Near Real Time ForWarn System for Detecting, Monitoring, and Analyzing Regional Forest Disturbances

    Science.gov (United States)

    Spruce, Joseph P.; Hargrove, William; Gasser, Jerry; Smoot, James; Kuper, Philip D.

    2014-01-01

    This presentation discusses MODIS NDVI change detection methods and products used in the ForWarn Early Warning System (EWS) for near real time (NRT) recognition and tracking of regionally evident forest disturbances throughout the conterminous US (CONUS). The latter has provided NRT forest change products to the forest health protection community since 2010, using temporally processed MODIS Aqua and Terra NDVI time series data to currently compute and post 6 different forest change products for CONUS every 8 days. Multiple change products are required to improve detectability and to more fully assess the nature of apparent disturbances. Each type of forest change product reports per pixel percent change in NDVI for a given 24 day interval, comparing current versus a given historical baseline NDVI. EMODIS 7 day expedited MODIS MOD13 data are used to obtain current and historical NDVIs, respectively. Historical NDVI data is processed with Time Series Product Tool (TSPT); and 2) the Phenological Parameters Estimation Tool (PPET) software. While each change products employ maximum value compositing (MVC) of NDVI, the design of specific products primarily differs in terms of the historical baseline. The three main change products use either 1, 3, or all previous years of MVC NDVI as a baseline. Another product uses an Adaptive Length Compositing (ALC) version of MVC to derive an alternative current NDVI that is the freshest quality NDVI as opposed to merely the MVC NDVI across a 24 day time frame. The ALC approach can improve detection speed by 8 to 16 days. ForWarn also includes 2 change products that improve detectability of forest disturbances in lieu of climatic fluctuations, especially in the spring and fall. One compares current MVC NDVI to the zonal maximum under the curve NDVI per pheno-region cluster class, considering all previous years in the MODIS record. The other compares current maximum NDVI to the mean of maximum NDVI for all previous MODIS years.

  18. Spatio-temporal reconstruction of air temperature maps and their application to estimate rice growing season heat accumulation using multi-temporal MODIS data

    Institute of Scientific and Technical Information of China (English)

    Li-wen ZHANG; Jing-feng HUANG; Rui-fang GUO; Xin-xing LI; Wen-bo SUN; Xiu-zhen WANG

    2013-01-01

    The accumulation of thermal time usually represents the local heat resources to drive crop growth.Maps of temperature-based agro-meteorological indices are commonly generated by the spatial interpolation of data collected from meteorological stations with coarse geographic continuity.To solve the critical problems of estimating air temperature(Ta)and filling in missing pixels due to cloudy and low-quality images in growing degree days(GDDs)calculation from remotely sensed data,a novel spatio-temporal algorithm for Ta estimation from Terra and Aqua moderate resolution imaging spectroradiometer(MODIS)data was proposed.This is a preliminary study to calculate heat accumulation,expressed in accumulative growing degree days(AGDDs)above 10 ℃,from reconstructed Ta based on MODIS land surface temperature(LST)data.The verification results of maximum Ta,minimum Ta,GDD,and AGDD from MODIS-derived data to meteorological calculation were all satisfied with high correlations over 0.01 significant levels.Overall,MODIS-derived AGDD was slightly underestimated with almost 10% relative error.However,the feasibility of employing AGDD anomaly maps to characterize the 2001-2010 spatio-temporal variability of heat accumulation and estimating the 2011 heat accumulation distribution using only MODIS data was finally demonstrated in the current paper.Our study may supply a novel way to calculate AGDD in heat-related study concerning crop growth monitoring,agricultural climatic regionalization,and agro-meteorological disaster detection at the regional scale.

  19. Air temperature field distribution estimations over a Chinese mega-city using MODIS land surface temperature data: the case of Shanghai

    Institute of Scientific and Technical Information of China (English)

    Weichun MA; Liguo ZHOU; Hao ZHANG; Yan ZHANG; Xiaoyan DAI

    2016-01-01

    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 250 m 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.

  20. India, the Modi challenges: poverty, diplomacy and security

    Directory of Open Access Journals (Sweden)

    Miguel Alejandro Rivas López

    2015-08-01

    Full Text Available This article is about the main challenges India's new Prime Minister, Narendra Modi, will face in his first term as a newly appointed Pm. Having recently been elected, this may, in an election process that represented the biggest blow that the former ruling party, the National Congress, has suffered in its entire history. This is a severe question to the legitimacy of the Nehru-Gandhi dinasty. The article reflects upon the policies India is adopting and the new challenges regarding foreign relations with other emerging economies like Pakistan, China and Japan, as well as internal concerns, such as lack of energetic and hidraulic infrastructure, on top of that the poverty issue is putting a lot of pressure on the new Pm. Will he be up to the task?

  1. Acoustic Modeling for Aqua Ventus I off Monhegan Island, ME

    Energy Technology Data Exchange (ETDEWEB)

    Whiting, Jonathan M.; Hanna, Luke A.; DeChello, Nicole L.; Copping, Andrea E.

    2013-10-31

    The DeepCwind consortium, led by the University of Maine, was awarded funding under the US Department of Energy’s Offshore Wind Advanced Technology Demonstration Program to develop two floating offshore wind turbines in the Gulf of Maine equipped with Goldwind 6 MW direct drive turbines, as the Aqua Ventus I project. The Goldwind turbines have a hub height of 100 m. The turbines will be deployed in Maine State waters, approximately 2.9 miles off Monhegan Island; Monhegan Island is located roughly 10 miles off the coast of Maine. In order to site and permit the offshore turbines, the acoustic output must be evaluated to ensure that the sound will not disturb residents on Monhegan Island, nor input sufficient sound levels into the nearby ocean to disturb marine mammals. This initial assessment of the acoustic output focuses on the sound of the turbines in air by modeling the assumed sound source level, applying a sound propagation model, and taking into account the distance from shore.

  2. MODIS Snow Cover Mapping Decision Tree Technique: Snow and Cloud Discrimination

    Science.gov (United States)

    Riggs, George A.; Hall, Dorothy K.

    2010-01-01

    Accurate mapping of snow cover continues to challenge cryospheric scientists and modelers. The Moderate-Resolution Imaging Spectroradiometer (MODIS) snow data products have been used since 2000 by many investigators to map and monitor snow cover extent for various applications. Users have reported on the utility of the products and also on problems encountered. Three problems or hindrances in the use of the MODIS snow data products that have been reported in the literature are: cloud obscuration, snow/cloud confusion, and snow omission errors in thin or sparse snow cover conditions. Implementation of the MODIS snow algorithm in a decision tree technique using surface reflectance input to mitigate those problems is being investigated. The objective of this work is to use a decision tree structure for the snow algorithm. This should alleviate snow/cloud confusion and omission errors and provide a snow map with classes that convey information on how snow was detected, e.g. snow under clear sky, snow tinder cloud, to enable users' flexibility in interpreting and deriving a snow map. Results of a snow cover decision tree algorithm are compared to the standard MODIS snow map and found to exhibit improved ability to alleviate snow/cloud confusion in some situations allowing up to about 5% increase in mapped snow cover extent, thus accuracy, in some scenes.

  3. Near real time detection of deforestation in the Brazilian Amazon using MODIS imagery

    Directory of Open Access Journals (Sweden)

    Egídio Arai

    2007-06-01

    Full Text Available The objective of this paper is to provide near real time information about deforestation detection (DETER in the entire Brazilian Amazon using MODIS high temporal resolution images. It is part of the operational deforestation monitoring project to estimate the annual deforestation rate in the Brazilian Amazon (PRODES. A rapid deforestation detection method was designed to support land use policies in this region. In order to evaluate the proposed method a test site was selected covering a Landsat ETM+ scene (227/68 located in Mato Grosso State. For this purpose a multitemporal series of MODIS surface reflectance images (MOD09 and the corresponding ETM+ images from June to October 2002 were analyzed. It was found that small deforested areas (lower than 15 ha were detected by MODIS images with lower accuracy when compared with ETM+ images. As the deforested areas increase MODIS and ETM+ results tend to converge. This procedure showed to be adequate to operationally detect and monitor deforested areas and has been used since 2004 as part of a government plan to control the Amazon deforestation.

  4. Assessment of the short-term radiometric stability between Terra MODIS and Landsat 7 ETM+ sensors

    Science.gov (United States)

    Choi, Taeyoung; Xiong, Xiaoxiong; Chander, Gyanesh; Angal, A.

    2009-01-01

    Short-term radiometric stability was evaluated using continuous ETM+ scenes within a single orbit (contact period) and the corresponding MODIS scenes for the four matching solar reflective visible and near-infrared (VNIR) band pairs between the two sensors. The near-simultaneous earth observations were limited by the smaller swath size of ETM+ (183 km) compared to MODIS (2330 km). Two sets of continuous granules for Terra MODIS and Landsat 7 ETM+ were selected and mosaicked based on pixel geolocation information for noncloudy pixels over the African continent. The matching pixel pairs were resampled from a fine to a coarse pixel resolution, and the at-sensor spectral radiance values for a wide dynamic range of the sensors were compared and analyzed, covering various surface types. The following study focuses on radiometric stability analysis from the VNIR band-pairs of ETM+ and MODIS. The Libya-4 desert target was included in the path of this continuous orbit, which served as a verification point between the short-term and the long-term trending results from previous studies. MODTRAN at-sensor spectral radiance simulation is included for a representative desert surface type to evaluate the consistency of the results.

  5. Evaluation of the MODIS Albedo Product over a Heterogeneous Agricultural Area

    Science.gov (United States)

    Sobrino, Jose Antonio; Franch, B.; Oltra-Carrio, R.; Vermote, E. F.; Fedele, E.

    2013-01-01

    In this article, the Moderate Resolution Imaging Spectroradiometer (MODIS) Bidirectional Reflectance Distribution Function (BRDF)/Albedo product (MCD43) is evaluated over a heterogeneous agricultural area in the framework of the Earth Observation: Optical Data Calibration and Information Extraction (EODIX) project campaign, which was developed in Barrax (Spain) in June 2011. In this method, two models, the RossThick-LiSparse-Reciprocal (RTLSR) (which corresponds to the MODIS BRDF algorithm) and the RossThick-Maignan-LiSparse-Reciprocal (RTLSR-HS), were tested over airborne data by processing high-resolution images acquired with the Airborne Hyperspectral Scanner (AHS) sensor. During the campaign, airborne images were retrieved with different view zenith angles along the principal and orthogonal planes. Comparing the results of applying the models to the airborne data with ground measurements, we obtained a root mean square error (RMSE) of 0.018 with both RTLSR and RTLSR-HS models. The evaluation of the MODIS BRDF/Albedo product (MCD43) was performed by comparing satellite images with AHS estimations. The results reported an RMSE of 0.04 with both models. Additionally, taking advantage of a homogeneous barley pixel, we compared in situ albedo data to satellite albedo data. In this case, the MODIS albedo estimation was (0.210 +/- 0.003), while the in situ measurement was (0.204 +/- 0.003). This result shows good agreement in regard to a homogeneous pixel.

  6. Validation of MODIS Data for localized spatio-temporal evapotranspiration mapping

    International Nuclear Information System (INIS)

    Advancement in satellite remote sensing sensors allows evapo-transpiration (ET) from land surfaces to be derived from selected reflectance and emmitance in visible and thermal infrared wavelengths, such as using Moderate Solution Imaging Spectrometer (MODIS). In this paper, we report the validation of recent MODIS-generated higher-order global terrestrial ET product 16A2. The main focus of this paper is to devise the follow-up calibration for the localised region covering the entire Malaysia peninsular. The validation is carried out locally by dividing the study area into 3 distinct climatological regions based on the influence to monsoons, and using multi-temporal MODIS data acquired in 2000-2009. The results, evidently show the local effects still inherit in the MODIS 16A2 products; with varying R2 within the 3 local climatological regions established (Northwest = 0.49 South = 0.47, and Southwest = 0.52; all with P < 0.001). The accuracy of each region validated is within + RMSE 43mm for monthly ET. With P value in acceptable range, the correction is useable for further usage

  7. An investigation of a potential low bias in the MODIS aerosol products over Asia

    Science.gov (United States)

    McHardy, T. M.; Shi, Y.; Zhang, J.; Reid, J. S.; Campbell, J. R.; Hsu, N. Y. C.

    2015-12-01

    Heavy aerosol plumes can be misidentified as clouds in passive satellite-based aerosol retrievals due to their relatively high visible reflectivity. Thus, over regions such as China, where a higher frequency of heavy aerosol plumes is expected, regional aerosol optical depth analyses reported from passive satellite-based aerosol products may biased low. This fundamental error can be suppressed under certain conditions. In this study, with a synergistic use of satellite observations from MODIS, OMI and CALIOP, a low bias in the MODIS Dark Target (DT) and Deep Blue (DB) aerosol products is studied over Asia for the influence of dense aerosol plume undersampling. A new scheme has been developed for detecting heavy aerosol plumes by coupling OMI aerosol index retrievals with available CALIOP level 1B and cloud and aerosol profile data. Collocated CALIOP, MODIS and OMI data are then used to further investigate the potential low bias in the MODIS DT and DB aerosol products, in an attempt to quantify the measure of undersampling in the regional DT and DB archive. Our preliminary results show that DT and DB aerosol algorithms detect about half heavy aerosol loading when CALIPSO and OMI AI believe there are heavy absorbing aerosols.

  8. Near real time detection of deforestation in the Brazilian Amazon using MODIS imagery

    Directory of Open Access Journals (Sweden)

    Maurício A. Moreira

    2006-08-01

    Full Text Available The objective of this paper is to provide near real time information about deforestation detection (DETER in the entire Brazilian Amazon using MODIS high temporal resolution images. It is part of the operational deforestation monitoring project to estimate the annual deforestation rate in the Brazilian Amazon (PRODES. A rapid deforestation detection method was designed to support land use policies in this region. In order to evaluate the proposed method a test site was selected covering a Landsat ETM+ scene (227/68 located in Mato Grosso State. For this purpose a multitemporal series of MODIS surface reflectance images (MOD09 and the corresponding ETM+ images from June to October 2002 were analyzed. It was found that small deforested areas (lower than 15 ha were detected by MODIS images with lower accuracy when compared with ETM+ images. As the deforested areas increase MODIS and ETM+ results tend to converge. This procedure showed to be adequate to operationally detect and monitor deforested areas and has been used since 2004 as part of a government plan to control the Amazon deforestation.

  9. Inter- and intra-annual variations of clumping index derived from the MODIS BRDF product

    Science.gov (United States)

    He, Liming; Liu, Jane; Chen, Jing M.; Croft, Holly; Wang, Rong; Sprintsin, Michael; Zheng, Ting; Ryu, Youngryel; Pisek, Jan; Gonsamo, Alemu; Deng, Feng; Zhang, Yongqin

    2016-02-01

    Clumping index quantifies the level of foliage aggregation, relative to a random distribution, and is a key structural parameter of plant canopies and is widely used in ecological and meteorological models. In this study, the inter- and intra-annual variations in clumping index values, derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) BRDF product, are investigated at six forest sites, including conifer forests, a mixed deciduous forest and an oak-savanna system. We find that the clumping index displays large seasonal variation, particularly for the deciduous sites, with the magnitude in clumping index values at each site comparable on an intra-annual basis, and the seasonality of clumping index well captured after noise removal. For broadleaved and mixed forest sites, minimum clumping index values are usually found during the season when leaf area index is at its maximum. The magnitude of MODIS clumping index is validated by ground data collected from 17 sites. Validation shows that the MODIS clumping index can explain 75% of variance in measured values (bias = 0.03 and rmse = 0.08), although with a narrower amplitude in variation. This study suggests that the MODIS BRDF product has the potential to produce good seasonal trajectories of clumping index values, but with an improved estimation of background reflectance.

  10. Comparison Between MODIS/NDVI and MODIS/EVI in Northwest China%西北地区MODIS/NDVI与MODIS/EVI对比分析

    Institute of Scientific and Technical Information of China (English)

    杨嘉; 郭铌; 贾建华

    2007-01-01

    为了了解西北地区MODIS/NDVI和MODIS/EVI 2种植被指数的特点,利用2003年植被生长期TERRA/MODIS资料和西北地区植被类型数据,分析了西北地区MODIS/NDVI和MODIS/EVI空间分布特征和不同类型植被随时间变化特征,比较了大气订正对NDVI和EVI的影响.结果表明:NDVI和EVI空间分布格局一致,与降水空间分布形式比较一致.NDVI与EVI值的差异随着植被覆盖度的增加而增大.不同类型植被NDVI和EVI变化特征一致.大气对NDVI和EVI的影响较大,大气订正前许多地区NDVI值小于EVI值.大气订正使NDVI增大,EVI减小,大气订正后NDVI值普遍大于EVI值.通过对大气气溶胶粒子较多地区的NDVI和EVI值的对比分析,EVI具有较好的抗大气气溶胶的作用.

  11. Consistency of land surface reflectance data: presentation of a new tool and case study with Formosat-2, SPOT-4 and Landsat-5/7/8 data

    Science.gov (United States)

    Claverie, M.; Vermote, E.; Franch, B.; Huc, M.; Hagolle, O.; Masek, J.

    2013-12-01

    Maintaining consistent dataset of Surface Reflectance (SR) data derived from the large panel of in-orbit sensors is an important challenge to ensure long term analysis of earth observation data. Continuous validation of such SR products through comparison with a reference dataset is thus an important challenge. Validating with in situ or airborne SR data is not easy since the sensors rarely match completely the same spectral, spatial and directional characteristics of the satellite measurement. Inter-comparison between satellites sensors data appears as a valuable tool to maintain a long term consistency of the data. However, satellite data are acquired at various times of the day (i.e., variation of the atmosphere content) and within a relative large range of geometry (view and sun angles). Also, even if band-to-band spectral characteristics of optical sensors are closed, they rarely have identical spectral responses. As the results, direct comparisons without consideration of these differences are poorly suitable. In this study, we suggest a new systematic method to assess land optical SR data from high to medium resolution sensors. We used MODIS SR products (MO/YD09CMG) which benefit from a long term calibration/validation process, to assess SR from 3 sensors data: Formosat-2 (280 scenes 24x24km - 5 sites), SPOT-4 (62 scenes 120x60km - 1 site) and Landsat-5/7 (104 180x180km scenes - 50 sites). The main issue concerns the difference in term of geometry acquisition between MODIS and compared sensors data. We used the VJB model (Vermote et al. 2009, TGRS) to correct MODIS SR from BRDF effects and to simulate SR at the corresponding geometry (view and sun angles) of each pixel of the compared sensor data. The comparison is done at the CMG spatial resolution (0.05°) which ensures a constant field-of-view and negligible geometrical errors. Figure 1 displays the summary of the NIR results through APU graphs where metrics A, P and U stands for Accuracy, Precision and

  12. Particulate matter concentration mapping from MODIS satellite data: a Vietnamese case study

    International Nuclear Information System (INIS)

    Particulate Matter (PM) pollution is one of the most important air quality concerns in Vietnam. In this study, we integrate ground-based measurements, meteorological and satellite data to map temporal PM concentrations at a 10 × 10 km grid for the entire of Vietnam. We specifically used MODIS Aqua and Terra data and developed statistically-significant regression models to map and extend the ground-based PM concentrations. We validated our models over diverse geographic provinces i.e., North East, Red River Delta, North Central Coast and South Central Coast in Vietnam. Validation suggested good results for satellite-derived PM2.5 data compared to ground-based PM2.5 (n = 285, r2 = 0.411, RMSE = 20.299 μg m−3 and RE = 39.789%). Further, validation of satellite-derived PM2.5 on two independent datasets for North East and South Central Coast suggested similar results (n = 40, r2 = 0.455, RMSE = 21.512 μg m−3, RE = 45.236% and n = 45, r2 = 0.444, RMSE = 8.551 μg m−3, RE = 46.446% respectively). Also, our satellite-derived PM2.5 maps were able to replicate seasonal and spatial trends of ground-based measurements in four different regions. Our results highlight the potential use of MODIS datasets for PM estimation at a regional scale in Vietnam. However, model limitation in capturing maximal or minimal PM2.5 peaks needs further investigations on ground data, atmospheric conditions and physical aspects. (letter)

  13. A Prototype MODI- SSM/I Snow Mapping Algorithm

    Science.gov (United States)

    Tait, Andrew B.; Barton, Jonathan S.; Hall, Dorothy K.

    1999-01-01

    Data in the wavelength range 0.545 - 1.652 microns from the Moderate Resolution Imaging Spectroradiometer (MODIS), to be launched aboard the Earth Observing System (EOS) Terra in the fall of 1999, will be used to map daily global snow cover at 500m resolution. However, during darkness, or when the satellite's view of the surface is obscured by cloud, snow cover cannot be mapped using MODIS data. We show that during these conditions, it is possible to supplement the MODIS product by mapping the snow cover using passive microwave data from the Special Sensor Microwave Imager (SSM/I), albeit with much poorer resolution. For a 7-day time period in March 1999, a prototype MODIS snow-cover product was compared with a prototype MODIS-SSM/I product for the same area in the mid-western United States. The combined MODIS-SSM/I product mapped 9% more snow cover than the MODIS-only product.

  14. Estimation of Daily Air Temperature Based on MODIS Land Surface Temperature Products over the Corn Belt in the US

    Directory of Open Access Journals (Sweden)

    Linglin Zeng

    2015-01-01

    Full Text Available Air temperature (Ta is a key input in a wide range of agroclimatic applications. Moderate Resolution Imaging Spectroradiometer (MODIS Ts (Land Surface Temperature (LST products are widely used to estimate daily Ta. However, only daytime LST (Ts-day or nighttime LST (Ts-night data have been used to estimate Tmax/Tmin (daily maximum or minimum air temperature, respectively. The relationship between Tmax and Ts-night, and the one between Tmin and Ts-day has not been studied. In this study, both the ability of Ts-night data to estimate Tmax and the ability of Ts-day data to estimate Tmin were tested and studied in the Corn Belt during the growing season (May–September from 2008 to 2012, using MODIS daily LST products from both Terra and Aqua. The results show that using Ts-night for estimating Tmax could result in a higher accuracy than using Ts-day for a similar estimate. Combining Ts-day and Ts-night, the estimation of Tmax was improved by 0.19–1.85, 0.37–1.12 and 0.26–0.93 °C for crops, deciduous forest and developed areas, respectively, when compared with using only Ts-day or Ts-night data. The main factors influencing the Ta estimation errors spatially and temporally were analyzed and discussed, such as satellite overpassing time, air masses, irrigation, etc.

  15. Safety dose of three commercially used growth promoters:nuricell-aqua, hepaprotect-aqua and rapid-grow on growth and survival of Thai pangas (Pangasianodon hypophthalmus)

    Institute of Scientific and Technical Information of China (English)

    Md Ariful Islam; Md Shaheed Reza; Md Alamgir; Md Khalilur Rahman; Md Kamal; Subhash Chandra Chakraborty

    2014-01-01

    Objective: To optimize the dose of 3 commonly used growth promoters, viz., Nuricell-Aqua (composition: glucomannan complex and mannose polymer), Hepaprotect-Aqua (composition:β-glucan, mannose polymer and essential oil) and Rapid-Grow (composition: organic acid and their salt, β-glucan, mannose oligosaccharide and essential oil), using Thai pangas (Pangasiandon hypophthalmus) as cultured species.Methods:Thai pangas fingerlings with an average length and weight of 11 cm and 10 g were reared under laboratory condition and growth promoters were fed after incorporating them with a test diet at a ratio of 10% of their body weight for a period of 28 d. Estimation of data on growth such as weight gain (g), specific growth rate, survivability (%) test in each aquarium were conducted and data were analyzed using statistical software.Results:After 28 d of feeding with Nutricell-Aqua, 10 mg/(20 g feed·day), which was the dose recommended by the manufacturer, was found better. When Hepaprotect-Aqua and Rapid-Grow were employed, performance was found to be better with the dose of 60 mg/(20 g feed·day) which was 1.5 times higher than the dose recommended by the corresponding manufacturer.Conclusions:These results suggest that chemicals and feed additives marketed in Bangladesh Fish Feed Market need further testing under Bangladesh climatic condition before being marketed.

  16. OMMYDCLD: a New A-train Cloud Product that Co-locates OMI and MODIS Cloud and Radiance Parameters onto the OMI Footprint

    Science.gov (United States)

    Fisher, Brad; Joiner, Joanna; Vasilkov, Alexander; Veefkind, Pepijn; Platnick, Steven; Wind, Galina

    2014-01-01

    Clouds cover approximately 60% of the earth's surface. When obscuring the satellite's field of view (FOV), clouds complicate the retrieval of ozone, trace gases and aerosols from data collected by earth observing satellites. Cloud properties associated with optical thickness, cloud pressure, water phase, drop size distribution (DSD), cloud fraction, vertical and areal extent can also change significantly over short spatio-temporal scales. The radiative transfer models used to retrieve column estimates of atmospheric constituents typically do not account for all these properties and their variations. The OMI science team is preparing to release a new data product, OMMYDCLD, which combines the cloud information from sensors on board two earth observing satellites in the NASA A-Train: Aura/OMI and Aqua/MODIS. OMMYDCLD co-locates high resolution cloud and radiance information from MODIS onto the much larger OMI pixel and combines it with parameters derived from the two other OMI cloud products: OMCLDRR and OMCLDO2. The product includes histograms for MODIS scientific data sets (SDS) provided at 1 km resolution. The statistics of key data fields - such as effective particle radius, cloud optical thickness and cloud water path - are further separated into liquid and ice categories using the optical and IR phase information. OMMYDCLD offers users of OMI data cloud information that will be useful for carrying out OMI calibration work, multi-year studies of cloud vertical structure and in the identification and classification of multi-layer clouds.

  17. Validation of MODIS Aerosol Optical Depth Retrieval over Mountains in Central China Based on a Sun-Sky Radiometer Site of SONET

    Directory of Open Access Journals (Sweden)

    Yan Ma

    2016-02-01

    Full Text Available The 3 km Dark Target (DT aerosol optical depth (AOD products, 10 km DT and Deep Blue (DB AOD products from the Collection 6 (C6 product data of Moderate Resolution Imaging Spectroradiometer (MODIS are compared with Sun-sky Radiometer Network (SONET measurements at Song Mountain in central China, where ground-based remote sensing measurements of aerosol properties are still very limited. The seasonal variations of AODs are significant in the Song Mountain region, with higher AODs in spring and summer and lower AODs in autumn and winter. Annual mean AODs (0.55 µm vary in the range of 0.5–0.7, which indicates particle matter (PM pollutions in this mountain region. Validation against one-year ground-based measurements shows that AOD retrievals from the MODIS onboard Aqua satellite are better than those from the Terra satellite in Song Mountain. The 3 km and 10 km AODs from DT algorithms are comparable over this region, while the AOD accuracy of DB algorithm is relatively lower. However, the spatial coverage of DB products is higher than that of 10 km DT products. Moreover, the optical and microphysical characteristics of aerosols at Song Mountain are analyzed on the basis of SONET observations. It suggests that coarse-mode aerosol particles dominate in spring, and fine-mode particles dominate in summer. The aerosol property models are also established and compared to aerosol types used by MODIS algorithm.

  18. Validation of Long-Term Global Aerosol Climatology Project Optical Thickness Retrievals Using AERONET and MODIS Data

    Science.gov (United States)

    Geogdzhayev, Igor V.; Mishchenko, Michael I.

    2015-01-01

    A comprehensive set of monthly mean aerosol optical thickness (AOT) data from coastal and island AErosol RObotic NETwork (AERONET) stations is used to evaluate Global Aerosol Climatology Project (GACP) retrievals for the period 1995-2009 during which contemporaneous GACP and AERONET data were available. To put the GACP performance in broader perspective, we also compare AERONET and MODerate resolution Imaging Spectroradiometer (MODIS) Aqua level-2 data for 2003-2009 using the same methodology. We find that a large mismatch in geographic coverage exists between the satellite and ground-based datasets, with very limited AERONET coverage of open-ocean areas. This is especially true of GACP because of the smaller number of AERONET stations at the early stages of the network development. Monthly mean AOTs from the two over-the-ocean satellite datasets are well-correlated with the ground-based values, the correlation coefficients being 0.81-0.85 for GACP and 0.74-0.79 for MODIS. Regression analyses demonstrate that the GACP mean AOTs are approximately 17%-27% lower than the AERONET values on average, while the MODIS mean AOTs are 5%-25% higher. The regression coefficients are highly dependent on the weighting assumptions (e.g., on the measure of aerosol variability) as well as on the set of AERONET stations used for comparison. Comparison of over-the-land and over-the-ocean MODIS monthly mean AOTs in the vicinity of coastal AERONET stations reveals a significant bias. This may indicate that aerosol amounts in coastal locations can differ significantly from those in adjacent open-ocean areas. Furthermore, the color of coastal waters and peculiarities of coastline meteorological conditions may introduce biases in the GACP AOT retrievals. We conclude that the GACP and MODIS over-the-ocean retrieval algorithms show similar ranges of discrepancy when compared to available coastal and island AERONET stations. The factors mentioned above may limit the performance of the

  19. A framework for consistent estimation of leaf area index, fraction of absorbed photosynthetically active radiation, and surface albedo from MODIS time-series data

    DEFF Research Database (Denmark)

    Xiao, Zhiqiang; Liang, Shunlin; Wang, Jindi;

    2015-01-01

    model and the MODIS surface reflectance data. The estimated LAI values were then input into the ACRM to calculate the surface albedo and the fraction of absorbed photosynthetically active radiation (FAPAR). For snow-covered areas, the surface albedo was calculated as the underlying vegetation canopy...... albedo plus the weighted distance between the underlying vegetation canopy albedo and the albedo over deep snow. The LAI/FAPAR and surface albedo values estimated using this framework were compared with MODIS collection 5 eight-day 1-km LAI/FAPAR products (MOD15A2) and 500-m surface albedo product (MCD43......-surface parameter profiles from MODIS time-series reflectance data even if some of the reflectance data are contaminated by residual cloud or are missing and that the retrieved LAI, FAPAR, and surface albedo values are physically consistent. The root mean square errors of the retrieved LAI, FAPAR, and surface...

  20. Global 500-m Estimates Of Land Surface Phenology For 2001-2008 From MODIS

    Science.gov (United States)

    Friedl, M. A.; Ganguly, S.; Tan, B.; Verma, M.

    2008-12-01

    Information related to vegetation phenology is important for understanding seasonal and interannual variability in ecosystems, carbon exchange, and vegetation-climate interactions. MODIS, the Moderate Resolution Imaging Spectroradiometer, provides an excellent source of data for large scale repeatable monitoring of phenology at global scales. This paper describes recent results from the Collection 5 (C5) MODIS Global Land Cover Dynamics product (MOD12Q2), which provides global data sets related to the timing, nature, and magnitude of vegetation phenology. The MOD12Q2 algorithm for estimating phenology is based on fitting piecewise logistic models to time series data of the Enhanced Vegetation Index (EVI) calculated from MODIS C5 Nadir BRDF-adjusted reflectance data. Our results show that the C5 Land Cover Dynamics product represents a significant step forward relative to previous MODIS products. In particular, the use of EVI data derived at 500-m spatial resolution and eight-day time intervals provides substantially improved temporal and spatial resolution relative to the Collection 4 (C4) product, which used 1-km, 16-day inputs. To assess C5 results, we evaluated the new C5 dataset extensively at a global scale for multiple years via (1) comparison with the MODIS C4 1-km product (a benchmark for our comparison), and (2) direct comparison of C5 phenological metrics with field observations collected at several sites in the northeastern United States. The results show general agreement of the C5 product with the C4 product in a majority of biomes, but with improved quality of the former compared to the latter. In addition, examination of C5 data sets exhibit significantly fewer missing values relative to C4, and generally in good agreement with ground measurements. Moving forward, the results from this analysis suggest that the MOD12Q2 product provides a good basis for seasonal to decadal scale studies of coupled climate-vegetation variability.