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Sample records for aqua modis satellite

  1. Synergetic retrieval of terrestrial AOD from MODIS images of twin satellites Terra and Aqua

    NASA Astrophysics Data System (ADS)

    He, Junliang; Zha, Yong; Zhang, Jiahua; Gao, Jay; Wang, Qiang

    2014-05-01

    Aerosol optical depth (AOD) is one of the most important indicators of atmospheric pollution. It can be retrieved from satellite imagery using several established methods, such as the dark dense vegetation method and the deep blue algorithm. All of these methods require estimation of surface reflectance prior to retrieval, and are applicable to a certain pre-designated type of surface cover. Such limitations can be overcome by using a synergetic method of retrieval proposed in this study. This innovative method is based on the fact that the ratio K of surface reflectance at different angles/geometries is independent of wavelength as reported by Flowerdew and Haigh (1995). An atmospheric radiative transfer model was then established and resolved with the assistance of the ratio K obtained from two Moderate Resolution Imaging Spectroradiometer (MODIS) spectral bands acquired from the twin satellites of Terra and Aqua whose overpass is separated by three hours. This synergetic method of retrieval was tested with 20 pairs of MODIS images. The retrieved AOD was validated against the ground observed AOD at the Taihu station of the AErosol RObotic NETwork (AERONET). It is found that they are correlated with the observations at a coefficient of 0.828 at 0.47 μm and 0.921 at 0.66 μm wavelengths. The retrieved AOD has a mean relative error of 25.47% at 0.47 μm and 24.3% at 0.66 μm. Of the 20 samples, 15 and 17 fall within two standard error of the line based observed AOD data on the ground at the 0.47 μm and 0.66 μm, respectively. These results indicate that this synergetic method can be used to reliably retrieve AOD from the twin satellites MODIS images, namely Terra and Aqua. It is not necessary to determine surface reflectance first.

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

    NASA Technical Reports Server (NTRS)

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

    2006-01-01

    The Moderate Resolution Imaging Spectroradiometer (MODIS) was developed by NASA and launched onboard the Terra spacecraft on December 18,1999 and Aqua spacecraft on May 4, 2002. It achieved its final orbit and began Earth observations on February 24,2000 for Terra and June 24,2002 for Aqua. A comprehensive set of remote sensing algorithms for cloud masking and the retrieval of cloud physical and optical properties has been developed by members of the MODIS atmosphere science team. The archived products from these algorithms have applications in climate change studies, climate modeling, numerical weather prediction, and fundamental atmospheric research. 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. Over the last year, extensive improvements and enhancements in the global cloud products have been implemented, and reprocessing of all MODIS data on Terra has commenced since first light in February 2000. In the cloud mask algorithm, the most extensive improvements were in distinguishing clouds at nighttime, including the challenging polar darkness regions of the world. Additional improvements have been made to properly distinguish sunglint from clouds in the tropical ocean regions, and to improve the identification of clouds from snow during daytime in Polar Regions. We will show global monthly mean cloud fraction for both Terra and Aqua, and show how similar the global daytime cloud fraction is from these morning and afternoon orbits, respectively. We will also show the zonal distribution of cloud fraction over land and ocean regions for both Terra and Aqua, and show the time series of global cloud fraction from July 2002 through June 2006.

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

    NASA Technical Reports Server (NTRS)

    King, Michael D.

    2005-01-01

    The Moderate Resolution Imaging Spectroradiometer (MODIS) was developed by NASA and launched onboard the Terra spacecraft on December 18, 1999 and Aqua spacecraft on May 4, 2002. It achieved its final orbit and began Earth observations on February 24, 2000 for Terra and June 24, 2002 for Aqua. A comprehensive set of remote sensing algorithms for cloud masking and the retrieval of cloud physical and optical properties has been developed by members of the MODIS atmosphere science team. The archived products from these algorithms have applications in climate change studies, climate modeling, numerical weather prediction, as well as fundamental atmospheric research. 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. We will describe the various cloud properties being analyzed on a global basis from both Terra and Aqua. These include the latitudinal distribution of cloud optical and radiative properties of both liquid water and ice clouds, as well as joint histograms of cloud optical thickness and effective radius for selected geographical locations around the world.

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

    NASA Technical Reports Server (NTRS)

    King, Michael D.; Platnick, Steven

    2005-01-01

    The Moderate Resolution Imaging Spectroradiometer (MODIS) was developed by NASA and launched onboard the Terra spacecraft on December 18,1999 and Aqua spacecraft on May 4, 2002. It achieved its final orbit and began Earth observations on February 24, 2000 for Terra and June 24, 2002 for Aqua. A comprehensive set of remote sensing algorithms for cloud masking and the retrieval of cloud physical and optical properties has been developed by members of the MODIS atmosphere science team. The archived products from these algorithms have applications in climate change studies, climate modeling, numerical weather prediction, as well as fundamental atmospheric research. 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. We will describe the various cloud properties being analyzed on a global basis from both Terra and Aqua. These include the latitudinal distribution of cloud optical and radiative properties of both liquid water and ice clouds, as well as joint histograms of cloud optical thickness and effective radius for selected geographical locations around the world.

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

    NASA Technical Reports Server (NTRS)

    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 afternoon deep convection. The coldest cloud tops (colder than 230 K) generally occur over Antarctica and the high clouds in the tropics (ITCZ and the deep convective clouds over the western tropical Pacific and Indian sub-continent).

  6. Seasonal nitrate algorithms for nitrate retrieval using OCEANSAT-2 and MODIS-AQUA satellite data.

    PubMed

    Durairaj, Poornima; Sarangi, Ranjit Kumar; Ramalingam, Shanthi; Thirunavukarassu, Thangaradjou; Chauhan, Prakash

    2015-04-01

    In situ datasets of nitrate, sea surface temperature (SST), and chlorophyll a (chl a) collected during the monthly coastal samplings and organized cruises along the Tamilnadu and Andhra Pradesh coast between 2009 and 2013 were used to develop seasonal nitrate algorithms. The nitrate algorithms have been built up based on the three-dimensional regressions between SST, chl a, and nitrate in situ data using linear, Gaussian, Lorentzian, and paraboloid function fittings. Among these four functions, paraboloid was found to be better with the highest co-efficient of determination (postmonsoon: R2=0.711, n=357; summer: R2=0.635, n=302; premonsoon: R2=0.829, n=249; and monsoon: R2=0.692, n=272) for all seasons. Based on these fittings, seasonal nitrate images were generated using the concurrent satellite data of SST from Moderate Resolution Imaging Spectroradiometer (MODIS) and chlorophyll (chl) from Ocean Color Monitor (OCM-2) and MODIS. The best retrieval of modeled nitrate (R2=0.527, root mean square error (RMSE)=3.72, and mean normalized bias (MNB)=0.821) was observed for the postmonsoon season due to the better retrieval of both SST MODIS (28 February 2012, R2=0.651, RMSE=2.037, and MNB=0.068) and chl OCM-2 (R2=0.534, RMSE=0.317, and MNB=0.27). Present results confirm that the chl OCM-2 and SST MODIS retrieve nitrate well than the MODIS-derived chl and SST largely due to the better retrieval of chl by OCM-2 than MODIS. PMID:25762424

  7. Spatial and Temporal Distribution of Tropospheric Clouds and Aerosols Observed by MODIS Onboard the Terra and Aqua Satellites

    NASA Technical Reports Server (NTRS)

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

    2006-01-01

    Remote sensing of cloud and aerosol optical properties is routinely obtained using the Moderate Resolution Imaging Spectroradiometer (MODIS) onboard the Terra and Aqua satellites. Instruments that are being used to enhance our ability to characterize the global distribution of cloud and aerosol properties include well-calibrated multispectral radiometers that measure in the visible, near-infrared, and thermal infrared. The availability of thermal channels to enhance detection of cloud when estimating aerosol properties is an important improvement. In this paper, we describe the radiative properties of clouds as currently determined from satellites (cloud fraction, optical thickness, cloud top pressure, and cloud particle effective radius) and highlight the global/regional cloud microphysical properties currently available for assessing climate variability and forcing. These include the latitudinal distribution of cloud optical and radiative properties of both liquid water and ice clouds, as well as joint histograms of cloud optical thickness and effective particle radius for selected geographical locations around the world. In addition, we will illustrate the radiative and microphysical properties of aerosol particles (in cloud free regions) that are currently available from space-based observations, and show the latitudinal distribution of aerosol optical properties over both land and ocean surfaces.

  8. Spatial and Temporal Distribution of Tropospheric Clouds and Aerosols Observed by MODIS Onboard the Terra and Aqua Satellites

    NASA Technical Reports Server (NTRS)

    King, Michael D.; Platnick, Steven; Remer, Lorraine A.; Kaufman, Yoram J.

    2004-01-01

    Remote sensing of cloud and aerosol optical properties is routinely obtained using the Moderate Resolution Imaging Spectroradiometer (MODIS) onboard the Terra and Aqua satellites. Techniques that are being used to enhance our ability to characterize the global distribution of cloud and aerosol properties include well-calibrated multispectral radiometers that rely on visible, near-infrared, and thermal infrared channels. The availability of thermal channels to aid in cloud screening for aerosol properties is an important additional piece of information that has not always been incorporated into sensor designs. In this paper, we describe the radiative properties of clouds as currently determined from satellites (cloud fraction, optical thickness, cloud top pressure, and cloud effective radius), and highlight the global and regional cloud microphysical properties currently available for assessing climate variability and forcing. These include the latitudinal distribution of cloud optical and radiative properties of both liquid water and ice clouds, as well as joint histograms of cloud optical thickness and effective radius for selected geographical locations around the world. In addition, we will illustrate the radiative and microphysical properties of aerosol particles that are currently available from space-based observations, and show selected cases in which aerosol particles are observed to modify the cloud optical properties.

  9. Temporal and Spatial Distribution of Liquid Water and Ice Clouds Observed by MODIS Onboard the Terra and Aqua Satellites

    NASA Technical Reports Server (NTRS)

    King, Michael D.; Platnick, S.; Gray, M. A.; Hubanks, P. A.

    2004-01-01

    The Moderate Resolution Imaging Spectroradiometer (MODE) was developed by NASA and launched onboard the Terra spacecraft on December 18,1999 and the Aqua spacecraft on April 26,2002. MODIS scans a swath width sufficient to provide nearly complete global coverage every two days from each polar-orbiting, sun-synchronous, platform at an altitude of 705 km, and 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). In this paper, we describe the radiative properties of clouds as currently determined from satellites (cloud fraction, optical thickness, cloud top pressure, and cloud effective radius), and highlight the global and regional cloud microphysical properties currently available for assessing climate variability and forcing. These include the latitudinal distribution of cloud optical and radiative properties of both liquid water and ice clouds, as well as joint histograms of cloud optical thickness and effective radius for selected geographical locations around the globe.

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

  11. Aqua satellite orbiting the Earth - Duration: 116 seconds.

    NASA Video Gallery

    This animation shows the Aqua satellite orbiting the Earth on August 27, 2005 by revealing MODIS true-color imagery for that day. This animation is on a cartesian map projection, so the satellite w...

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

    NASA Technical Reports Server (NTRS)

    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.

  13. Adjusting Aqua MODIS TEB nonlinear calibration coefficients using iterative solution

    NASA Astrophysics Data System (ADS)

    Wu, Aisheng; Wang, Zhipeng; Li, Yonghong; Madhavan, Sriharsha; Wenny, Brian N.; Chen, Na; Xiong, Xiaoxiong

    2014-11-01

    Radiometric calibration is important for continuity and reliability of any optical sensor data. The Moderate Resolution Imaging Spectroradiometer (MODIS) onboard NASA EOS (Earth Observing System) Aqua satellite has been nominally operating since its launch on May 4, 2002. The MODIS thermal emissive bands (TEB) are calibrated using a quadratic calibration algorithm and the dominant gain term is determined every scan by reference to a temperature-controlled blackbody (BB) with known emissivity. On a quarterly basis, a BB warm-up and cool-down (WUCD) process is scheduled to provide measurements to determine the offset and nonlinear coefficients used in the TEB calibration algorithm. For Aqua MODIS, the offset and nonlinear terms are based on the results from prelaunch thermal vacuum tests. However, on-orbit trending results show that they have small but noticeable drifts. To maintain data quality and consistency, an iterative approach is applied to adjust the prelaunch based nonlinear terms, which are currently used to produce Aqua MODIS Collection-6 L1B. This paper provides details on how to use an iterative solution to determine these calibration coefficients based on BB WUCD measurements. Validation is performed using simultaneous nadir overpasses (SNO) of Aqua MODIS and the Infrared Atmospheric Sounding Interferometer (IASI) onboard the Metop-A satellite and near surface temperature measurements at Dome C on the Antarctic Plateau.

  14. Synergism of MODIS Aerosol Remote Sensing from Terra and Aqua

    NASA Technical Reports Server (NTRS)

    Ichoku, Charles; Kaufman, Yoram J.; Remer, Lorraine A.

    2003-01-01

    The MODerate-resolution Imaging Spectro-radiometer (MODIS) sensors, aboard the Earth Observing System (EOS) Terra and Aqua satellites, are showing excellent competence at measuring the global distribution and properties of aerosols. Terra and Aqua were launched on December 18, 1999 and May 4, 2002 respectively, with daytime equator crossing times of approximately 10:30 am and 1:30 pm respectively. Several aerosol parameters are retrieved at 10-km spatial resolution from MODIS daytime data over land and ocean surfaces. The parameters retrieved include: aerosol optical thickness (AOT) at 0.47, 0.55 and 0.66 micron wavelengths over land, and at 0.47, 0.55, 0.66, 0.87, 1.2, 1.6, and 2.1 microns over ocean; Angstrom exponent over land and ocean; and effective radii, and the proportion of AOT contributed by the small mode aerosols over ocean. Since the beginning of its operation, the quality of Terra-MODIS aerosol products (especially AOT) have been evaluated periodically by cross-correlation with equivalent data sets acquired by ground-based (and occasionally also airborne) sunphotometers, particularly those coordinated within the framework of the AErosol Robotic NETwork (AERONET). Terra-MODIS AOT data have been found to meet or exceed pre-launch accuracy expectations, and have been applied to various studies dealing with local, regional, and global aerosol monitoring. The results of these Terra-MODIS aerosol data validation efforts and studies have been reported in several scientific papers and conferences. Although Aqua-MODIS is still young, it is already yielding formidable aerosol data products, which are also subjected to careful periodic evaluation similar to that implemented for the Terra-MODIS products. This paper presents results of validation of Aqua-MODIS aerosol products with AERONET, as well as comparative evaluation against corresponding Terra-MODIS data. In addition, we show interesting independent and synergistic applications of MODIS aerosol data from both Terra and Aqua. In certain situations, this combined analysis of Terra- and Aqua-MODIS data offers an insight into the diurnal cycle of aerosol loading.

  15. Inter-Comparison of Terra and Aqua MODIS

    NASA Technical Reports Server (NTRS)

    Xiong, X.; Salomonson, V. V.; Sun, J.; Wu, A.; Barnes, W.; Guenther, B.

    2004-01-01

    Nearly identical copies of the Moderate Resolution Imaging Spectroradiometer (MODIS) 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. Each MODIS has 20 reflective solar bands (RSB) with center wavelengths ranging from 0.41 to 2.1 micrometers and 16 thermal emissive bands (TEB) from 3.7 to 14.4 micrometers. The absolute radiometric accuracy requirements (1 sigma) at the typical spectral radiance levels are plus or minus 2% for the RSB for the RSB reflectance factors and plus or minus 5% for the RSB radiance products. With few exceptions, the TEB requirements are plus or minus 1%. The sensor's on-orbit radiometric calibration is performed by the on-board calibrators, including a solar diffuser (SD) and a solar diffuser stability monitor (SDSM) system for the RSB and a V-groove flat panel blackbody (BB) for the TEB. In addition, the Moon has been extensively used by both Terra and Aqua MODIS to support their on-orbit calibration and characterization. This paper presents MODIS lunar calibration methodology and inter-comparison of Terra and Aqua MODIS in the VIS/NIR spectral regions. Current results from lunar observations show that the calibration difference between the two sensors is less than plus or minus 1%. Also discussed in this paper are the approaches and results of inter-comparison of Terra and Aqua MODIS in the TEB using closely matched thermal infrared (TIR) channels on the Advanced Very High Resolution Radiometer (AVHRR) at 11 and 12 micrometers.

  16. Surface Albedo/BRDF Parameters (Terra/Aqua MODIS)

    DOE Data Explorer

    Trishchenko, Alexander

    2008-01-15

    Spatially and temporally complete surface spectral albedo/BRDF products over the ARM SGP area were generated using data from two Moderate Resolution Imaging Spectroradiometer (MODIS) sensors on Terra and Aqua satellites. A landcover-based fitting (LBF) algorithm is developed to derive the BRDF model parameters and albedo product (Luo et al., 2004a). The approach employs a landcover map and multi-day clearsky composites of directional surface reflectance. The landcover map is derived from the Landsat TM 30-meter data set (Trishchenko et al., 2004a), and the surface reflectances are from MODIS 500m-resolution 8-day composite products (MOD09/MYD09). The MOD09/MYD09 data are re-arranged into 10-day intervals for compatibility with other satellite products, such as those from the NOVA/AVHRR and SPOT/VGT sensors. The LBF method increases the success rate of the BRDF fitting process and enables more accurate monitoring of surface temporal changes during periods of rapid spring vegetation green-up and autumn leaf-fall, as well as changes due to agricultural practices and snowcover variations (Luo et al., 2004b, Trishchenko et al., 2004b). Albedo/BRDF products for MODIS on Terra and MODIS on Aqua, as well as for Terra/Aqua combined dataset, are generated at 500m spatial resolution and every 10-day since March 2000 (Terra) and July 2002 (Aqua and combined), respectively. The purpose for the latter product is to obtain a more comprehensive dataset that takes advantages of multi-sensor observations (Trishchenko et al., 2002). To fill data gaps due to cloud presence, various interpolation procedures are applied based on a multi-year observation database and referring to results from other locations with similar landcover property. Special seasonal smoothing procedure is also applied to further remove outliers and artifacts in data series.

  17. Status of Terra and Aqua MODIS Instruments

    NASA Technical Reports Server (NTRS)

    Xiong, Xiaoxiong; Wenny, Brian N.; Kuyper, James; Salomonson, Vicent; Barmes. William

    2008-01-01

    Currently, two nearly identical MODIS instruments are operating in space: one on the Terra spacecraft launched in December 1999 and another on the Aqua spacecraft launched in May 2002. MODIS has 36 spectral bands with wavelengths covering from visible (VIS) to long-wave infrared (LWIR). Since launch, MODIS observations and data products have contributed significantly to studies of changes in the Earth system of land, oceans, and atmosphere. To maintain its on-orbit calibration and data product quality, MODIS was built with a comprehensive set of on-board calibrators, consisting of a solar diffuser (SD) and a solar diffuser stability monitor (SDSM) for the reflective solar bands (RSB) and an on-board blackbody (BB) for the thermal emissive bands (TEB). Both instruments have demonstrated good performance. The primary Level 1 B (LIB) data products are top of the atmosphere (TOA) reflectance for RSB and radiance for TEB This paper provides an overview of MODIS calibration methodologies, activities, lifetime on-orbit performance and challenging issues for each MODIS, the impact on LIB product quality, and lessons learned for future sensors such as the NPOESS VIIRS.

  18. CERES Single Scanner Satellite Footprint, TOA, Surface Fluxes and Clouds (SSF) data in HDF (CER_SSF_Aqua-FM4-MODIS_Edition1B)

    NASA Technical Reports Server (NTRS)

    Wielicki, Bruce A. (Principal Investigator)

    The Single Scanner Footprint TOA/Surface Fluxes and Clouds (SSF) product contains one hour of instantaneous Clouds and the Earth's Radiant Energy System (CERES) data for a single scanner instrument. The SSF combines instantaneous CERES data with scene information from a higher-resolution imager such as Visible/Infrared Scanner (VIRS) on TRMM or Moderate-Resolution Imaging Spectroradiometer (MODIS) on Terra and Aqua. Scene identification and cloud properties are defined at the higher imager resolution and these data are averaged over the larger CERES footprint. For each CERES footprint, the SSF contains the number of cloud layers and for each layer the cloud amount, height, temperature, pressure, optical depth, emissivity, ice and liquid water path, and water particle size. The SSF also contains the CERES filtered radiances for the total, shortwave (SW), and window (WN) channels and the unfiltered SW, longwave (LW), and WN radiances. The SW, LW, and WN radiances at spacecraft altitude are converted to Top-of-the-Atmosphere (TOA) fluxes based on the imager defined scene. These TOA fluxes are used to estimate surface fluxes. Only footprints with adequate imager coverage are included on CER_SSF_TRMM-PFM-VIRS_Subset_Edition1the SSF which is much less than the full set of footprints on the CERES ES-8 product. The following CERES SSF data sets are currently available: CER_SSF_TRMM-PFM-VIRS_Edition1 CER_SSF_TRMM-PFM-VIRS_Subset_Edition1 CER_SSF_TRMM-PFM-VIRS_Edition2A CER_SSF_TRMM-SIM-VIRS_Edition2_VIRSonly CER_SSF_TRMM-PFM-VIRS_Edition2A-TransOps CER_SSF_TRMM-PFM-VIRS_Edition2B-TransOps CER_SSF_TRMM-PFM-VIRS_Edition2B CER_SSF_Terra-FM1-MODIS_Edition1A CER_SSF_Terra-FM1-MODIS_Edition1A CER_SSF_Terra-FM1-MODIS_Edition2A CER_SSF_Terra-FM2-MODIS_Edition2A CER_SSF_Terra-FM1-MODIS_Edition2B CER_SSF_Terra-FM2-MODIS_Edition2B CER_SSF_Aqua-FM4-MODIS_Beta1 CER_SSF_Aqua-FM3-MODIS_Beta2 CER_SSF_Aqua-FM4-MODIS_Beta2. [Location=GLOBAL] [Temporal_Coverage: Start_Date=1998-01-01; Stop_Date=2005-03-29] [Spatial_Coverage: Southernmost_Latitude=-90; Northernmost_Latitude=90; Westernmost_Longitude=-180; Easternmost_Longitude=180] [Data_Resolution: Temporal_Resolution=1 hour; Temporal_Resolution_Range=Hourly - < Daily].

  19. CERES Single Scanner Satellite Footprint, TOA, Surface Fluxes and Clouds (SSF) data in HDF (CER_SSF_Aqua-FM3-MODIS_Edition1B)

    NASA Technical Reports Server (NTRS)

    Wielicki, Bruce A. (Principal Investigator)

    The Single Scanner Footprint TOA/Surface Fluxes and Clouds (SSF) product contains one hour of instantaneous Clouds and the Earth's Radiant Energy System (CERES) data for a single scanner instrument. The SSF combines instantaneous CERES data with scene information from a higher-resolution imager such as Visible/Infrared Scanner (VIRS) on TRMM or Moderate-Resolution Imaging Spectroradiometer (MODIS) on Terra and Aqua. Scene identification and cloud properties are defined at the higher imager resolution and these data are averaged over the larger CERES footprint. For each CERES footprint, the SSF contains the number of cloud layers and for each layer the cloud amount, height, temperature, pressure, optical depth, emissivity, ice and liquid water path, and water particle size. The SSF also contains the CERES filtered radiances for the total, shortwave (SW), and window (WN) channels and the unfiltered SW, longwave (LW), and WN radiances. The SW, LW, and WN radiances at spacecraft altitude are converted to Top-of-the-Atmosphere (TOA) fluxes based on the imager defined scene. These TOA fluxes are used to estimate surface fluxes. Only footprints with adequate imager coverage are included on CER_SSF_TRMM-PFM-VIRS_Subset_Edition1the SSF which is much less than the full set of footprints on the CERES ES-8 product. The following CERES SSF data sets are currently available: CER_SSF_TRMM-PFM-VIRS_Edition1 CER_SSF_TRMM-PFM-VIRS_Subset_Edition1 CER_SSF_TRMM-PFM-VIRS_Edition2A CER_SSF_TRMM-SIM-VIRS_Edition2_VIRSonly CER_SSF_TRMM-PFM-VIRS_Edition2A-TransOps CER_SSF_TRMM-PFM-VIRS_Edition2B-TransOps CER_SSF_TRMM-PFM-VIRS_Edition2B CER_SSF_Terra-FM1-MODIS_Edition1A CER_SSF_Terra-FM1-MODIS_Edition1A CER_SSF_Terra-FM1-MODIS_Edition2A CER_SSF_Terra-FM2-MODIS_Edition2A CER_SSF_Terra-FM1-MODIS_Edition2B CER_SSF_Terra-FM2-MODIS_Edition2B CER_SSF_Aqua-FM4-MODIS_Beta1 CER_SSF_Aqua-FM3-MODIS_Beta2 CER_SSF_Aqua-FM4-MODIS_Beta2. [Location=GLOBAL] [Temporal_Coverage: Start_Date=1998-01-01; Stop_Date=2005-03-31] [Spatial_Coverage: Southernmost_Latitude=-90; Northernmost_Latitude=90; Westernmost_Longitude=-180; Easternmost_Longitude=180] [Data_Resolution: Temporal_Resolution=1 hour; Temporal_Resolution_Range=Hourly - < Daily].

  20. CERES Single Satellite Footprint, TOA and Surface Fluxes, Clouds (SSF) data in HDF (CER_SSF_Aqua-FM4-MODIS_Ed2A-NoSW)

    NASA Technical Reports Server (NTRS)

    Wielicki, Bruce A. (Principal Investigator)

    The Single Scanner Footprint TOA/Surface Fluxes and Clouds (SSF) product contains one hour of instantaneous Clouds and the Earth's Radiant Energy System (CERES) data for a single scanner instrument. The SSF combines instantaneous CERES data with scene information from a higher-resolution imager such as Visible/Infrared Scanner (VIRS) on TRMM or Moderate-Resolution Imaging Spectroradiometer (MODIS) on Terra and Aqua. Scene identification and cloud properties are defined at the higher imager resolution and these data are averaged over the larger CERES footprint. For each CERES footprint, the SSF contains the number of cloud layers and for each layer the cloud amount, height, temperature, pressure, optical depth, emissivity, ice and liquid water path, and water particle size. The SSF also contains the CERES filtered radiances for the total, shortwave (SW), and window (WN) channels and the unfiltered SW, longwave (LW), and WN radiances. The SW, LW, and WN radiances at spacecraft altitude are converted to Top-of-the-Atmosphere (TOA) fluxes based on the imager defined scene. These TOA fluxes are used to estimate surface fluxes. Only footprints with adequate imager coverage are included on CER_SSF_TRMM-PFM-VIRS_Subset_Edition1the SSF which is much less than the full set of footprints on the CERES ES-8 product. The following CERES SSF data sets are currently available: CER_SSF_TRMM-PFM-VIRS_Edition1 CER_SSF_TRMM-PFM-VIRS_Subset_Edition1 CER_SSF_TRMM-PFM-VIRS_Edition2A CER_SSF_TRMM-SIM-VIRS_Edition2_VIRSonly CER_SSF_TRMM-PFM-VIRS_Edition2A-TransOps CER_SSF_TRMM-PFM-VIRS_Edition2B-TransOps CER_SSF_TRMM-PFM-VIRS_Edition2B CER_SSF_Terra-FM1-MODIS_Edition1A CER_SSF_Terra-FM1-MODIS_Edition1A CER_SSF_Terra-FM1-MODIS_Edition2A CER_SSF_Terra-FM2-MODIS_Edition2A CER_SSF_Terra-FM1-MODIS_Edition2B CER_SSF_Terra-FM2-MODIS_Edition2B CER_SSF_Aqua-FM4-MODIS_Beta1 CER_SSF_Aqua-FM3-MODIS_Beta2 CER_SSF_Aqua-FM4-MODIS_Beta2. [Location=GLOBAL] [Temporal_Coverage: Start_Date=1998-01-01; Stop_Date=2006-01-01] [Spatial_Coverage: Southernmost_Latitude=-90; Northernmost_Latitude=90; Westernmost_Longitude=-180; Easternmost_Longitude=180] [Data_Resolution: Temporal_Resolution=1 hour; Temporal_Resolution_Range=Hourly - < Daily].

  1. CERES Single Satellite Footprint, TOA and Surface Fluxes, Clouds (SSF) data in HDF (CER_SSF_Aqua-FM3-MODIS_Edition2A)

    NASA Technical Reports Server (NTRS)

    Wielicki, Bruce A. (Principal Investigator)

    The Single Scanner Footprint TOA/Surface Fluxes and Clouds (SSF) product contains one hour of instantaneous Clouds and the Earth's Radiant Energy System (CERES) data for a single scanner instrument. The SSF combines instantaneous CERES data with scene information from a higher-resolution imager such as Visible/Infrared Scanner (VIRS) on TRMM or Moderate-Resolution Imaging Spectroradiometer (MODIS) on Terra and Aqua. Scene identification and cloud properties are defined at the higher imager resolution and these data are averaged over the larger CERES footprint. For each CERES footprint, the SSF contains the number of cloud layers and for each layer the cloud amount, height, temperature, pressure, optical depth, emissivity, ice and liquid water path, and water particle size. The SSF also contains the CERES filtered radiances for the total, shortwave (SW), and window (WN) channels and the unfiltered SW, longwave (LW), and WN radiances. The SW, LW, and WN radiances at spacecraft altitude are converted to Top-of-the-Atmosphere (TOA) fluxes based on the imager defined scene. These TOA fluxes are used to estimate surface fluxes. Only footprints with adequate imager coverage are included on CER_SSF_TRMM-PFM-VIRS_Subset_Edition1the SSF which is much less than the full set of footprints on the CERES ES-8 product. The following CERES SSF data sets are currently available: CER_SSF_TRMM-PFM-VIRS_Edition1 CER_SSF_TRMM-PFM-VIRS_Subset_Edition1 CER_SSF_TRMM-PFM-VIRS_Edition2A CER_SSF_TRMM-SIM-VIRS_Edition2_VIRSonly CER_SSF_TRMM-PFM-VIRS_Edition2A-TransOps CER_SSF_TRMM-PFM-VIRS_Edition2B-TransOps CER_SSF_TRMM-PFM-VIRS_Edition2B CER_SSF_Terra-FM1-MODIS_Edition1A CER_SSF_Terra-FM1-MODIS_Edition1A CER_SSF_Terra-FM1-MODIS_Edition2A CER_SSF_Terra-FM2-MODIS_Edition2A CER_SSF_Terra-FM1-MODIS_Edition2B CER_SSF_Terra-FM2-MODIS_Edition2B CER_SSF_Aqua-FM4-MODIS_Beta1 CER_SSF_Aqua-FM3-MODIS_Beta2 CER_SSF_Aqua-FM4-MODIS_Beta2. [Location=GLOBAL] [Temporal_Coverage: Start_Date=1998-01-01; Stop_Date=2006-01-01] [Spatial_Coverage: Southernmost_Latitude=-90; Northernmost_Latitude=90; Westernmost_Longitude=-180; Easternmost_Longitude=180] [Data_Resolution: Temporal_Resolution=1 hour; Temporal_Resolution_Range=Hourly - < Daily].

  2. CERES Single Satellite Footprint, TOA and Surface Fluxes, Clouds (SSF) data in HDF (CER_SSF_Aqua-FM4-MODIS_Edition2A)

    NASA Technical Reports Server (NTRS)

    Wielicki, Bruce A. (Principal Investigator)

    The Single Scanner Footprint TOA/Surface Fluxes and Clouds (SSF) product contains one hour of instantaneous Clouds and the Earth's Radiant Energy System (CERES) data for a single scanner instrument. The SSF combines instantaneous CERES data with scene information from a higher-resolution imager such as Visible/Infrared Scanner (VIRS) on TRMM or Moderate-Resolution Imaging Spectroradiometer (MODIS) on Terra and Aqua. Scene identification and cloud properties are defined at the higher imager resolution and these data are averaged over the larger CERES footprint. For each CERES footprint, the SSF contains the number of cloud layers and for each layer the cloud amount, height, temperature, pressure, optical depth, emissivity, ice and liquid water path, and water particle size. The SSF also contains the CERES filtered radiances for the total, shortwave (SW), and window (WN) channels and the unfiltered SW, longwave (LW), and WN radiances. The SW, LW, and WN radiances at spacecraft altitude are converted to Top-of-the-Atmosphere (TOA) fluxes based on the imager defined scene. These TOA fluxes are used to estimate surface fluxes. Only footprints with adequate imager coverage are included on CER_SSF_TRMM-PFM-VIRS_Subset_Edition1the SSF which is much less than the full set of footprints on the CERES ES-8 product. The following CERES SSF data sets are currently available: CER_SSF_TRMM-PFM-VIRS_Edition1 CER_SSF_TRMM-PFM-VIRS_Subset_Edition1 CER_SSF_TRMM-PFM-VIRS_Edition2A CER_SSF_TRMM-SIM-VIRS_Edition2_VIRSonly CER_SSF_TRMM-PFM-VIRS_Edition2A-TransOps CER_SSF_TRMM-PFM-VIRS_Edition2B-TransOps CER_SSF_TRMM-PFM-VIRS_Edition2B CER_SSF_Terra-FM1-MODIS_Edition1A CER_SSF_Terra-FM1-MODIS_Edition1A CER_SSF_Terra-FM1-MODIS_Edition2A CER_SSF_Terra-FM2-MODIS_Edition2A CER_SSF_Terra-FM1-MODIS_Edition2B CER_SSF_Terra-FM2-MODIS_Edition2B CER_SSF_Aqua-FM4-MODIS_Beta1 CER_SSF_Aqua-FM3-MODIS_Beta2 CER_SSF_Aqua-FM4-MODIS_Beta2. [Location=GLOBAL] [Temporal_Coverage: Start_Date=1998-01-01; Stop_Date=2005-09-16] [Spatial_Coverage: Southernmost_Latitude=-90; Northernmost_Latitude=90; Westernmost_Longitude=-180; Easternmost_Longitude=180] [Data_Resolution: Temporal_Resolution=1 hour; Temporal_Resolution_Range=Hourly - < Daily].

  3. Aqua MODIS 8-Year On-Orbit Operation and Calibration

    NASA Technical Reports Server (NTRS)

    Xiong, Xiaoxiong; Angal, Amit; Madhavan, Sriharsha; Choi, Taeyoung; Dodd, Jennifer; Geng, Xu; Wang, Zhipeng; Toller, Gary; Barnes, William

    2010-01-01

    Launched in May 2002, the NASA EOS Aqua MODIS has successfully operated for more than 8 years. Observations from Aqua MODIS and its predecessor, Terra MODIS, have generated an unprecedented amount of data products and made significant contributions to studies of changes in the Earth s system of land, oceans, and atmosphere. MODIS collects data in 36 spectral bands: 20 reflective solar bands (RSB) and 16 thermal emissive bands (TEB). It has a set of on-board calibrators (OBC), providing sensor on-orbit radiometric, spectral, and spatial calibration and characterization. This paper briefly summarizes Aqua MODIS on-orbit operation and calibration activities and illustrates instrument on-orbit performance from launch to present. Discussions are focused on OBC functions and changes in detector radiometric gains, spectral responses, and spatial registrations. With ongoing calibration effort, Aqua MODIS will continue serving the science community with high quality data products

  4. Study of the dynamics of the aerosol optical depth in South America from MODIS images of Terra and Aqua satellites (2000-2012)

    NASA Astrophysics Data System (ADS)

    Benavente, Noelia Rojas; Acuña, Joel Rojas

    2013-05-01

    The objective of this work is to study the dynamics of aerosols in South America (Latitude 4 ° N-24 ° S and Longitude 83 ° W-33 ° W) from monthly averages images aerosol optical thickness (AOT) of 550 nm from the MODIS sensor (TERRA and AQUA) of period 2000 to 2012. We also will hope to using AOT in-situ data from six AERONET stations (Brazil: Rio Branco, Paraná JI, HIGH FORESTA, Campo Grande; Chile: Arica and Bolivia: Santa Cruz) for its validation with MODIS AOT products of period 2000 to 2011. The AOT products and time series were extracted from GIOVANNI software. We have analyzed several time series (MODIS-Terra, MODIS-Aqua and AERONET) for establishing the aerosol's temporal variability over the study area (Latitude 4°N-24°S and Longitude 83°W-33°W). On the one hand, we have found that the AOT data extracted from GIOVANNI show to oscillate between 0.0 to 0.6, having their maximum values during the months of August and September (between 0.45 and 0.5), over a period of thirteen years (2000-2012). This increase is consistent with the onset of fires by farmers in the Amazon region, which is very common during the aforementioned months.

  5. Calibration Adjustments to the MODIS Aqua Ocean Color Bands

    NASA Technical Reports Server (NTRS)

    Meister, Gerhard

    2012-01-01

    After the end of the SeaWiFS mission in 2010 and the MERIS mission in 2012, the ocean color products of the MODIS on Aqua are the only remaining source to continue the ocean color climate data record until the VIIRS ocean color products become operational (expected for summer 2013). The MODIS on Aqua is well beyond its expected lifetime, and the calibration accuracy of the short wavelengths (412nm and 443nm) has deteriorated in recent years_ Initially, SeaWiFS data were used to improve the MODIS Aqua calibration, but this solution was not applicable after the end of the SeaWiFS mission_ In 2012, a new calibration methodology was applied by the MODIS calibration and support team using desert sites to improve the degradation trending_ This presentation presents further improvements to this new approach. The 2012 reprocessing of the MODIS Aqua ocean color products is based on the new methodology.

  6. Terra and Aqua MODIS Design, Radiometry, and Geometry in Support of Land Remote Sensing

    NASA Technical Reports Server (NTRS)

    Xiong, Xiaoxiong; Wolfe, Robert; Barnes, William; Guenther, Bruce; Vermote, Eric; Saleous, Nazmi; Salomonson, Vincent

    2011-01-01

    The NASA Earth Observing System (EOS) mission includes the construction and launch of two nearly identical Moderate Resolution Imaging Spectroradiometer (MODIS) instruments. The MODIS proto-flight model (PFM) is onboard the EOS Terra satellite (formerly EOS AM-1) launched on December 18, 1999 and hereafter referred to as Terra MODIS. Flight model-1 (FM1) is onboard the EOS Aqua satellite (formerly EOS PM-1) launched on May 04, 2002 and referred to as Aqua MODIS. MODIS was developed based on the science community s desire to collect multiyear continuous datasets for monitoring changes in the Earth s land, oceans and atmosphere, and the human contributions to these changes. It was designed to measure discrete spectral bands, which includes many used by a number of heritage sensors, and thus extends the heritage datasets to better understand both long- and short-term changes in the global environment (Barnes and Salomonson 1993; Salomonson et al. 2002; Barnes et al. 2002). The MODIS development, launch, and operation were managed by NASA/Goddard Space Flight Center (GSFC), Greenbelt, Maryland. The sensors were designed, built, and tested by Raytheon/ Santa Barbara Remote Sensing (SBRS), Goleta, California. Each MODIS instrument offers 36 spectral bands, which span the spectral region from the visible (0.41 m) to long-wave infrared (14.4 m). MODIS collects data at three different nadir spatial resolutions: 0.25, 0.5, and 1 km. Key design specifications, such as spectral bandwidths, typical scene radiances, required signal-to-noise ratios (SNR) or noise equivalent temperature differences (NEDT), and primary applications of each MODIS spectral band are summarized in Table 7.1. These parameters were the basis for the MODIS design. More details on the evolution of the NASA EOS and development of the MODIS instruments are provided in Chap. 1. This chapter focuses on the MODIS sensor design, radiometry, and geometry as they apply to land remote sensing. With near-daily coverage of the Earth's surface, MODIS provides comprehensive measurements that enable scientists and policy makers to better understand and effectively manage the natural resources on both regional and global scales. Terra, the first large multisensor EOS satellite, is operated in a 10:30 am (local equatorial crossing time, descending southwards) polar orbit. Aqua, the second multisensor EOS satellite is operated in a 1:30 pm (local equatorial crossing time, ascending northwards) polar orbit. With complementing morning and afternoon observations, the Terra and Aqua MODIS, together with other sensors housed on both satellites, have greatly improved our understanding of the dynamics of the global environmental system.

  7. Overview of Terra and Aqua MODIS Status

    NASA Technical Reports Server (NTRS)

    Salomonson, Vincent V.

    2005-01-01

    This presentation will consist of two one-hour lectures. The first lecture will review the characteristics of the MODIS instrument and how it responds to the performance specifications. The pre-launch and on-orbit procedures and results to characterize and maintain instrument output so as to allow the prescribed science to be done will also be outlined. This will include defining the equations used to account for gain changes and any degradation in the optics of the instrument or the on-board calibration devices themselves. The changes in the solar diffuser and the radiance versus scan angle performance of the scan mirror will also be reviewed. Overall it will be shown that the instrument has and is meeting specifications of 2% reflectance relative to the sun, 5% in the radiance observed in the reflected solar radiation bands, and 0.5-1% in the thermal bands. The second lecture will review and describe highlights in the geophysical products and related science results. There are approximately 40 geophysical products related to observations of land, ocean and atmosphere features. Many of the results are unprecedented and offer considerable advances over those achievable with heritage instruments such as the NOAA Advanced Very High Resolution Radiometer (AVHRR). The literature is showing a steady growth of publications in scientific journals using MODIS data or products. The future is also bright in that a follow-on instrument based on the MODIS will be flown on the National Polar-Orbiting Environmental Satellite Series (NPOESS) starting around 2010.

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

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

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

  9. Assessment of the Collection 6 Terra and Aqua MODIS bands 1 and 2 calibration performance

    NASA Astrophysics Data System (ADS)

    Wu, A.; Chen, X.; Angal, A.; Li, Y.; Xiong, X.

    2015-09-01

    MODIS (Moderate Resolution Imaging Spectroradiometer) is a key sensor aboard the Terra (EOS AM) and Aqua (EOS PM) satellites. MODIS collects data in 36 spectral bands and generates over 40 data products for land, atmosphere, cryosphere and oceans. MODIS bands 1 and 2 have nadir spatial resolution of 250 m, compared with 500 m for bands 3 to 7 and 1000 m for all the remaining bands, and their measurements are crucial to derive key land surface products. This study evaluates the calibration performance of the Collection-6 L1B for both Terra and Aqua MODIS bands 1 and 2 using three vicarious approaches. The first and second approaches focus on stability assessment using data collected from two pseudo-invariant sites, Libya 4 desert and Antarctic Dome C snow surface. The third approach examines the relative stability between Terra and Aqua in reference to a third sensor from a series of NOAA 15-19 Advanced Very High Resolution Radiometer (AVHRR). The comparison is based on measurements from MODIS and AVHRR Simultaneous Nadir Overpasses (SNO) over a thirteen-year period from 2002 to 2015. Results from this study provide a quantitative assessment of Terra and Aqua MODIS bands 1 and 2 calibration stability and the relative calibration differences between the two sensors.

  10. Status of Terra and Aqua MODIS Instrument Operation and Calibration

    NASA Astrophysics Data System (ADS)

    Xiong, X.; Wenny, B. N.; Sun, J.; Angal, A.; Salomonson, V. V.

    2013-12-01

    Terra and Aqua MODIS have successfully operated for more than 13 and 11 years since their respective launches in 1999 and 2002. Nearly 40 data products, developed for studies of the earth's land, ocean, and atmosphere, have been routinely generated from calibrated and geo-located MODIS observations and widely distributed to the science and user community. MODIS on-orbit calibration is performed by a set of on-board calibrators, which include a solar diffuser for the reflective solar bands calibration and a blackbody for the thermal emissive bands calibration. MODIS on-board calibrators are regularly operated to monitor on-orbit changes in sensor responses and key performance parameters, such as radiometric calibration coefficients. Since launch, extensive instrument calibration and characterization activities have been scheduled and executed by the MODIS Characterization Support Team (MCST). This presentation provides an overview of both Terra and Aqua MODIS instrument status, their on-orbit operation and calibration activities, and overall long-term performance. It reports calibration improvements (algorithms and look-up tables) made in the latest MODIS data collection (C6). Lessons learned from both Terra and Aqua MODIS and their applications to the S-NPP VIIRS on-orbit calibration are also discussed.

  11. Expanding the Estimation of Surface PM2.5 from Aqua and Terra MODIS Aerosol Optical Depth in the EPA's AirNow Satellite Data Processor to Suomi NPP VIIRS

    NASA Astrophysics Data System (ADS)

    Szykman, J.; Kondragunta, S.; Zhang, H.; Dickerson, P.; van Donkelaar, A.; Martin, R. V.; Pasch, A. N.; White, J. E.; DeWinter, J. L.; Zahn, P. H.; Dye, T. S.; Haderman, M. D.

    2012-12-01

    The U.S. Environmental Protection Agency's (EPA) Air Quality Index (AQI) relies on hourly measurements of ground-based surface PM2.5 (particles smaller than 2.5 ?m in median diameter) to develop daily AQI index maps. The EPA is improving the accuracy of AQI information and extending its coverage for reporting to the public by incorporating National Aeronautics and Space Administration (NASA) satellite-derived surface PM2.5 concentrations into daily AQI maps. The additional coverage will provide air quality information in regions without dense monitoring networks. The AirNow Satellite Data Processor (ASDP) uses daily PM2.5 estimates and uncertainties derived from average Aqua and Terra MODerate resolution Imaging Spectroradiometer (MODIS) aerosol optical depth (AOD) in near real-time over the United States. The algorithm to derive surface PM2.5 from MODIS AOD relies on linear relationships between AOD and PM2.5 generated from multi-year GEOS-Chem model simulations (van Donkelaar et al., 2012). Parameters from the regression equation (slopes and intercepts) are saved in a lookup table (LUT) with 4 km spatial resolution for each day of a given year. To improve data accuracy and continuity, a filter is applied to remove MODIS AOD with low accuracy (e.g., over bright surfaces) and an inverse distance weighted average is applied to fill in gaps created by cloud coverage. Daily surface PM2.5 estimates and their uncertainties are generated at the National Oceanic and Atmospheric Administration (NOAA) using the van Donkelaar et al. algorithm and near real-time MODIS AOD products from Terra and Aqua and are provided to the EPA through its Infusing satellite Data into Environmental Applications (IDEA) website. The Suomi National Polar-orbiting Partnership (NPP) Visible Infrared Imaging Radiometer Suite (VIIRS) was launched on October 28, 2011, and similar to MODIS, provides AOD products for real-time applications. NOAA plans to explore the value of VIIRS AOD products to improve AQI. This presentation will focus on a description of ASDP, including an overview of the algorithm used to estimate surface PM2.5 using satellite data and examples of high resolution VIIRS AOD products and their value to the ASDP. Disclaimer: Although this work was reviewed by the U.S. Environmental Protection Agency and approved for publication, it may not necessarily reflect official Agency policy.

  12. Status of Aqua MODIS On-orbit Calibration and Characterization

    NASA Technical Reports Server (NTRS)

    Xiong, X.; Barnes, W.; Chiang, K.; Erives, H.; Che, N.; Sun, J.; Isaacman, A.; Salomonson, V.

    2004-01-01

    The MODIS Flight Model 1 (FM1) has been in operation for more than two years since its launch onboard the NASA's Earth Observing System (EOS) Aqua spacecraft on May 4, 2002. The MODIS has 36 spectral bands: 20 reflective solar bands (RSB) with center wavelengths from 0.41 to 2.2 micron and 16 thermal emissive bands (TEB) from 3.7 to 14.5 micron. It provides the science community observations (data products) of the Earth's land, oceans, and atmosphere for a board range of applications. Its primary on-orbit calibration and characterization activities are performed using a solar diffuser (SD) and a solar diffuser stability monitor (SDSM) system for the RSB and a blackbody for the TEB. Another on-board calibrator (OBC) known as the spectro-radiometric calibration assembly (SRCA) is used for the instrument's spatial (TEB and RSB) and spectral (RSB only) characterization. We present in this paper the status of Aqua MODIS calibration and characterization during its first two years of on-orbit operation. Discussions will be focused on the calibration activities executed on-orbit in order to maintain and enhance the instrument's performance and the quality of its Level 1B (L1B) data products. We also provide comparisons between Aqua MODIS and Terra MODIS (launched in December, 1999), including their similarity and difference in response trending and optics degradation. Existing data and results show that Aqua MODIS bands 8 (0.412 micron) and 9 (0.443 micron) have much smaller degradation than Terra MODIS bands 8 and 9. The most noticeable feature shown in the RSB trending is that the mirror side differences in Aqua MODIS are extremely small and stable (<0.1%) while the Terra MODIS RSB trending has shown significant mirror side difference and wavelength dependent degradation. The overall stability of the Aqua MODIS TEB is also better than that of the Terra MODIS during their first two years of on-orbit operation.

  13. Cross-calibration of Landsat 5 TM and Landsat 8 OLI with Aqua MODIS using PICS

    NASA Astrophysics Data System (ADS)

    Angal, Amit; Mishra, Nischal; Xiong, Xiaoxiong; Helder, Dennis

    2014-09-01

    The Thematic Mapper (TM) onboard the Landsat 5 (L5) has provided an unprecedented amount of earth observations for more than 25 years since its launch on March 1, 1984. The MODIS sensor onboard the Aqua satellite is a part of the afternoon constellation of spacecraft and has been successfully providing near-continuous observations of the earth's surface and atmosphere since July 2002. A synergistic use of TM and MODIS reflective solar bands (RSB) measurements is immensely beneficial to the broad user community for different land cover change and global climate studies. A consistent radiometric calibration between the sensors is a prerequisite for creating high quality science products. Various pseudo-invariant calibration sites (PICS) identified by CEOS have been widely used to monitor the on-orbit calibration consistency for a number of sensors. Near-simultaneous observations of the Saharan PICS by L5 TM and Aqua MODIS are used in this study. The top-of-atmosphere (TOA) reflectance from the spectrally matching RSB are corrected for test site Bi-directional Reflectance Distribution Function (BRDF), relative spectral response (RSR) mismatch, and impacts for atmospheric water-vapor, and used to estimate the long-term calibration differences between the two sensors. The Operational Land Imager (OLI) onboard the Landsat 8 (L8) launched in February, 2013, is a follow-on mission to maintain the continuity of Landsat acquisitions. A similar cross-calibration methodology was extended to compare the spectrally matching bands of Aqua MODIS with OLI. A long-term drift is observed in bands 1 (3.7%) and 3 (1.86%) of L5 TM, which is expected to be mitigated in the next calibration coefficient update. With the exception of the SWIR-2 band (L5 TM band 7), the agreement with Aqua MODIS is seen to be within 4%. The L8 OLI and Aqua MODIS agreement is seen within 4% across all wavelengths.

  14. The regime of aerosol asymmetry parameter and Angstrom exponent over Europe, Mediterranean and Middle East based on MODIS satellite data. Intercomparison of MODIS-Aqua C051 and C006 retrievals

    NASA Astrophysics Data System (ADS)

    Korras-Carraca, Marios Bruno; Hatzianastassiou, Nikolaos; Matsoukas, Christos; Gkikas, Antonis; Papadimas, Christos; Sayers, Andy

    2015-04-01

    Atmospheric aerosols, both natural and anthropogenic, can cause climate change through their direct, indirect, and semi-direct effects on the radiative energy budget of the Earth-atmosphere system. In the present work, we study two of the most important optical properties of aerosols, the asymmetry parameter (gaer) and the Angstrom exponent (α). Both gaer and α are related with aerosol size, which is a very important parameter for climate and human health. The study region comprises North Africa, the Arabian peninsula, Europe, and the Mediterranean basin. These areas are of great interest, because of the variety of aerosol types they host, both anthropogenic and natural. Urban, industrial or biomass-burning aerosols are usually fine, while desert dust or sea-salt are basically coarse, making thus possible the establishment of a relationship between the type and the size of aerosols. Using satellite data from the collection 051 of MODIS (MODerate resolution Imaging Spectroradiometer, Aqua), we investigate the spatio-temporal characteristics of the asymmetry parameter and Angstrom exponent. We generally find significant spatial variability, with larger gaer values over regions dominated by larger size particles, e.g. outside the Atlantic coasts of north-western Africa, where desert-dust outflow is taking place. The gaer values tend to decrease with increasing wavelength, especially over areas dominated by small particulates. The intra-annual variability is found to be small in desert-dust areas, with maximum values during summer, while in all other areas larger values are reported during the cold season and smaller during the warm. Significant intra-annual and inter-annual variability is observed around the Black Sea. However, the inter-annual trends of gaer are found to be generally small. The geographical distributions for α (given for the pair of wavelengths 550-865 nm) affirm the conclusions drawn from the asymmetry parameter as regards the aerosol size over the study region, with larger α values in regions where the aerosol load is dominated by fine particles. A daily Angstrom exponent intercomparison is also performed between collection 051 and the most recent collection (006). Our results reveal a good agreement between the two datasets, with a correlation coefficient ranging between 0.75 and 0.95 above the study region.

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    Ice-surface temperature (IST) is used in many studies, for example for validation of model output and for detection of leads and thin ice in sea ice. The MODerate-resolution Imaging Spectroradiometer (MODIS) instruments on the Terra and Aqua satellites are useful for mapping IST of sea ice and the Greenland ice sheet (Hall et al., 2012), and validation of the ISTs derived from MODIS has been an ongoing effort (e.g., Koenig & Hall, 2010; Shuman et al., 2014). Recent results call into question the calibration of the MODIS-derived ISTs at very cold temperatures that are characteristic of the Greenland ice sheet high interior during winter (Shuman et al., 2014). In the present work, we investigate the calibration of MODIS IR bands 31 (10.780 - 11.280 µm) and 32 (11.770 - 12.270 µm) under very cold conditions. MODIS IR bands are calibrated using a quadratic algorithm. In Collection 6 (C6), the offset and nonlinear calibration coefficients are computed from data collected during the blackbody cool-down vs the warm-up data used in Collection 5 (C5). To improve the calibration accuracy for low-temperature scenes, the offset terms are set to 0. In general, Aqua MODIS bands 31 and 32 perform better than Terra MODIS bands 31 and 32. One of the reasons is that the Aqua bands have a lower saturation temperature (~340 K) than the Terra (~380 K) bands, and lower saturation or smaller dynamic range means better resolution. As compared to ~2-m NOAA air temperatures (TA) at Summit, Greenland, Shuman et al. (2014) show a small (~0.5°C) offset in Terra MODIS-derived IST vs TA near 0°C, and an increasingly larger offset (up to ~5°C) as TA drops to -60°C. To investigate this further, we compare Terra and Aqua C5 and C6 ISTs with TA data from Summit. This work will document the calibration of bands 31 and 32 at very low temperatures in C5 and C6. Hall, D.K., et al., 2012: Satellite-Derived Climate-Quality Data Record of the Clear-Sky Surface Temperature of the Greenland Ice Sheet, Jour. Clim., 25(14):4785-4798.Koenig, L.S. and D.K. Hall, 2010: Comparison of satellite, thermochron and station temperatures at Summit, Greenland, during the winter of 2008/09, Jour. Glaciol., 56(198):735-741. Shuman, C.A., et al., 2014: Comparison of near-surface air temperatures and MODIS ice-surface temperatures at Summit, Greenland (2008-2013), JAMC, in press.

  16. Aqua Satellite Mission Educational Outreach

    NASA Astrophysics Data System (ADS)

    Parkinson, C. L.; Graham, S. M.

    2003-12-01

    An important component of the Aqua mission, launched into space on May 4, 2002 with a suite of six instruments from the U.S., Japan, and Brazil, is the effort to educate the public about the mission and the science topics that it addresses. This educational outreach includes printed products, web casts, other web-based materials, animations, presentations, and a student contest. The printed products include brochures for the mission as a whole and for the instruments, NASA Fact Sheets on the mission, the water cycle, and weather forecasting, an Aqua Science Writers' Guide, an Aqua lithograph, posters, and trading cards. Animations include animations of the launch, the orbit, instrument deployments, instrument sensing, and several of the data products. Each of these materials is available on the Aqua web site at http://aqua.nasa.gov, as are archived versions of the eight Aqua web casts. The web casts were done live on the internet and focused on the spacecraft, the science, the launch, and the validation efforts. All web casts had key Aqua personnel as live guests and had a web-based chat session allowing viewers to ask questions. Other web-based materials include a "Cool Science" section of the aqua.nasa.gov website, with videos of Aqua scientists and engineers speaking about Aqua and the science and engineering behind it, arranged in a framework organized for the convenience of teachers dealing with core curriculum requirements. The web casts and "Cool Science" site were produced by the Special Project Initiatives Office at NASA's Goddard Space Flight Center. Outreach presentations about Aqua have been given at schools, universities, and public forums at many locations around the world, especially in the U.S. A competition was held for high school students during the 2002-03 school year, culminating in April 2003, with five finalist teams competing for the top slots, followed by an awards ceremony. The competition had all the student teams analyzing an anomalous situation encountered by Aqua shortly after launch and the five finalist teams determining how best to handle a hypothetical degradation of the solid state recorder.

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

    NASA Technical Reports Server (NTRS)

    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.

  18. Assessment of the Visible Channel Calibrations of the TRMM VIRS and MODIS on Aqua and Terra

    NASA Technical Reports Server (NTRS)

    Minnis, Patrick; Doelling, David R.; Nguyen, Louis; Miller, Walter F.; Chakrapani, Venketesan

    2007-01-01

    Several recent research satellites carry self-calibrating multispectral imagers that can be used for calibrating operational imagers lacking complete self-calibrating capabilities. In particular, the visible (VIS, 0.65 m) channels on operational meteorological satellites are generally calibrated before launch, but require vicarious calibration techniques to monitor the gains and offsets once they are in orbit. To ensure that the self-calibrating instruments are performing as expected, this paper examines the consistencies between the VIS channel (channel 1) reflectances of the Moderate Resolution Imaging Spectroradiometer (MODIS) instruments on the Terra and Aqua satellites and the Version 5a and 6 reflectances of the Visible Infrared Scanner (VIRS) on the Tropical Rainfall Measuring Mission using a variety of techniques. These include comparisons of Terra and Aqua VIS radiances with coincident broadband shortwave radiances from the well-calibrated Clouds and the Earth s Radiant Energy System (CERES), time series of deep convective cloud (DCC) albedos, and ray-matching intercalibrations between each of the three satellites. Time series of matched Terra and VIRS data, Aqua and VIRS data, and DCC reflected fluxes reveal that an older version (Version 5a, ending in early 2004) of the VIRS calibration produced a highly stable record, while the latest version (Version 6) appears to overestimate the sensor gain change by approx.1%/y as the result of a manually induced gain adjustment. Comparisons with the CERES shortwave radiances unearthed a sudden change in the Terra MODIS calibration that caused a 1.17% decrease in the gain on 19 November 2003 that can be easily reversed. After correction for these manual adjustments, the trends in the VIRS and Terra channels are no greater than 0.1%/y. Although the results were more ambiguous, no statistically significant trends were found in the Aqua MODIS channel-1 gain. The Aqua radiances are 1% greater, on average, than their Terra counterparts, and after normalization are 4.6% greater than VIRS radiances, in agreement with theoretical calculations. The discrepancy between the two MODIS instruments should be taken into account to ensure consistency between parameters derived from them. With the adjustments, any of the three instruments can serve as references for calibrating other satellites. Monitoring of the calibrations continues in near-real-time and the results are available via the world wide web.

  19. MODIS Cloud Products Derived from Terra and Aqua During CRYSTAL-FACE

    NASA Technical Reports Server (NTRS)

    King, Michael D.; Platnick, S.; Riedi, J. C.; Ackerman, S. A.; Menzel, W. P.

    2003-01-01

    The Moderate Resolution Imaging Spectroradiometer (MODIS), developed as part of the Earth Observing System (EOS) and launched on Terra in December 1999 and Aqua in May 2002, is designed to meet the scientific needs for satellite remote sensing of clouds, aerosols, water vapor, and land and ocean surface properties. During the CRYSTAL-FACE experiment, numerous aircraft coordinated both in situ and remote sensing observations with the Terra and Aqua spacecraft. In this paper we will emphasize the optical, microphysical, and physical properties of both liquid water and ice clouds obtained from an analysis of the satellite observations over Florida and the Gulf of Mexico during July 2002. We will present the frequency distribution of liquid water and ice cloud microphysical properties throughout the region, separating the results over land and ocean. Probability distributions of effective radius and cloud optical thickness will also be shown.

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

    NASA Astrophysics Data System (ADS)

    Glantz, P.; Tesche, M.

    2012-04-01

    Beside an increase of greenhouse gases (e.g., carbon dioxide, methane and nitrous oxide) human activities (for instance fossil fuel and biomass burning) have lead to perturbation of the atmospheric content of aerosol particles. Aerosols exhibits high spatial and temporal variability in the atmosphere. Therefore, aerosol investigation for climate research and environmental control require the identification of source regions, their strength and aerosol type, which can be retrieved based on space-borne observations. The aim of the present study is to validate and evaluate AOT (aerosol optical thickness) and Ångström exponent, 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), against AERONET (AErosol RObotic NETwork) observations and MODIS Collection 5 (c005) standard product retrievals (10 km), respectively, over land surfaces in Europe for the seasons; early spring (period 1), mid spring (period 2) and summer (period 3). 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 aerosol 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 retrievals over Europe (Δτ = ±0.05 ± 0.15τ). 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 RMSD (root mean square deviation) occurs compared to the results obtained with the MODIS c005 algorithm. The discrepancy between SAERand AERONET AOT is, however, substantially larger for the wavelength 488 nm, which means that several of the AOT values are without the MODIS expected uncertainty range. Both algorithms are unable to estimate Ångström exponent accurately, although the MODIS c005 algorithm performs a better job. Based on the inter-comparison of the SAER and MODIS c005 algorithms it was found here that the former estimation of AOT is for values up to 1on the whole within the expected uncertainties for one standard deviation of the MODIS retrievals, considering both Aqua and Terra and periods 1 and 3. The latter also occurs for Aqua and period 2, while then for AOT values lower than 0.5. The present algorithms were, beside aerosols emitted from clean sources and continental sources in Europe, also applied with favor on aerosol particles transported from agricultural fires in Russia and Ukraine. The latter events were associated with high aerosol loadings, although probably with similar single scattering albedo as the days classified as clean. We also present observations performed with space borne and ground-based lidars in the area investigated. From the latter platforms the vertical distribution of aerosol extinction in the atmosphere can be measured. This study suggests that the present satellite retrievals of AOT, particularly obtained with the MODIS c005 algorithm, will, in combination with the lidar measurements, be very useful in validation of regional and climate models over Europe.

  1. GES DAAC tools for accessing TERRA and AQUA MODIS data

    NASA Astrophysics Data System (ADS)

    Ouzounov, D.; Ahmad, S.; Eaton, ..; Koziana, J.; Leptoukh, G.; Nickless, D.; Ostrenga, D.; Savtchenko, A.; Serafino, G.; Sharma, A.; Zhou, B.

    The unique position of the NASA Goddard Earth Sciences Distributed Active Archive Center (GES DAAC) as an intermediary between users and TERRA and AQUA/MODIS data led us to explore and develop tools that could help users access and manipulate data. Some tools are DAAC unique extensions like search and order web pages or channel subsetting programs. Other data access and simple visualization tools were developed as MODIS Data Support Team (MDST) work aids.Alistofthesuggestedtoolsisavailableat http://daac.gsfc.nasa.gov/MODIS/software.html The key features of some of the improved tools available from GES DAAC are described below: WHOM: The Web-based Hierarchical Ordering Mechanism (WHOM) is a customized version of the larger GES DAAC web-based data gateway to MODIS data. WHOM offers enhanced graphic interfaces to identify temporal and spatial data coverage while searching and ordering MODIS data archived at the GES DAAC. Calendar page showing dates with available data, visual inspection of the spatial data distribution for the selected region, filtering granules by Day/Night flag, single point and click navigational protocols, and recursive web page generation using templates make this tool unique and positive step to address the needs of the user community. The WHOM for Terra has been operational since February 2000. The same approach is being used to provide a gateway to MODIS data from the AQUA platform starting late summer 2002. Subsetting Tools: Calibrated radiance (Level 1B, 1km) channel subsetting was developed as a DAAC unique extension to the EOS Core System (ECS). The front end, a graphic user interface, is an added feature of the WHOM system. The back end is driven by the new Simple Scalable Script-Based Science Processor (S4P) that interacts with ECS for data retrieval, archiving and distribution of the subsetted data. All three resolutions of MODIS Level 1B data will be available for channel subsetting in the future. Visualization Tools: The GES DAAC MDST has developed two very simple IDL- based tools dedicated to mapping MODIS swath products. The first, geoview, has a simple, graphic interface, while the second, simap, is a command line utility. While the two tools are almost identical, simap has the added feature of stitching multiple granules into a single map. HDFLook_MODIS : Beta version of this tool has been released recently and it is a product of joint collaboration between the GES DAAC MDST and the University of Lille, France to update the popular HDFLook for future MODIS needs. The program includes multi-level MODIS data functionality and is designed to process all MODIS products. Its main features include, re - mapping, geo-projection conversion, interactive and batch mode capabilities, subsetting features, mosaic or stitch, multi- granule processing, and GIS conversion.

  2. Terra and Aqua MODIS Products and Data Tools Available From NASA GES DAAC

    NASA Astrophysics Data System (ADS)

    Ouzounov, D.; Savtchenko, A.; Leptoukh, G.; Zhou, B.; Nickless, D.; Ostrenga, D.; Gopalan, A.; Yuan, D.; Shen, S.

    2003-04-01

    The Moderate Resolution Imaging Spectroradiometer (MODIS), a major NASA Earth Observing System (EOS) instrument, was launched aboard the Terra satellite on December 18, 1999 (10:30 am equator crossing time, descending) for global monitoring of the atmosphere, the terrestrial ecosystems and oceans. On May 4, 2002, a similar instrument was launched on the EOS-Aqua Satellite (1:30 pm equator crossing time, ascending). Thus MODIS, flying in a formation of two satellites, will enable scientists to study diurnal variation of the rapidly varying systems and will provide a long term data set for the same geophysical parameters for the study of climate and global change studies. MODIS, with its 2330 km viewing swath width, provides almost daily Global coverage. It acquires data in 36 high spectral resolution bands between 0.415 and 14.235 micron with spatial resolutions of 250m (2 bands), 500 (5 bands), and 1000m (29 bands). The radiance data measured by MODIS at high spatial resolution with some new channels (never used before for the remote sensing) provides improved and valuable information about the physical structure of the Earth's atmosphere and surface. NASA Goddard Earth Sciences Data and Information Services Center (GES DISC) Distributed Active Archive Center (DAAC), seen as GSFC-ECS in the Earth Observing System Data Gateway, distributes three major groups of MODIS data: Level 1 Radiometric and Geolocations, and all levels of Atmosphere and Ocean. The Atmosphere data types are: Aerosol, Water Vapor, Cloud, Profiles, and Cloud Mask. The 107 (at present) Ocean data types contain Normalized Water Leaving Radiances, Ocean Color, Sea Surface Temperatures, and Ocean Primary Productivity (OPP). To facilitate users navigate through the complex structure of MODIS information, the MODIS Data Support Team (MDST) was established at the GES DISC DAAC. The Team provides a broad spectrum of services covering: data access, visualization tools, tools for search and order of the aforementioned data, documentation, data content, troubleshooting, science and software support for the EOS Core System. The search and order tools include DAAC-unique extensions such as: the Web-based Hierarchical Ordering Mechanism (WHOM); the multi-product ordering system; and MODIS Level 1B channel subsetting. Visualization and data manipulation tools, exemplified by include HDFLook_MODIS, resulted from joint GES DAAC, University of Lille, and MODIS Science team cooperation. Furthermore, simple IDL tools were developed at GES DAAC as work aids. The key features of some of the improved tools available from GES DAAC are described. Please, visit us at: http://daac.gsfc.nasa.gov/MODIS/

  3. Calibration and Characterization of the NASA EOS Terra and Aqua MODIS Instruments

    NASA Technical Reports Server (NTRS)

    Salomonson, Vincent V.

    2005-01-01

    The Moderate Resolution Imaging Spectroradiometer (MODIS) instrument is operating on both of the Terra and Aqua missions within the NASA Earth Observing System (EOS). The Terra MODIS instrument began taking observations in February 2000 and the Aqua MODIS instrument began taking observations in June of 2002 and both continue to operate successfully up to the present time. The MODIS instrument scans the entire Earth every 24 hours at nominal spatial resolutions between 250 and 1000 meters. It has 36 spectral bands spanning the electromagnetic spectrum from the visible wavelengths mar 400 micrometers to the emissive thermal infrared wavelengths at 15 micrometers. The MODIS instruments produce approximately 40 geophysical products devoted to observing land, ocean, and atmospheric processes and trends. To meet the scientific objectives associated with the NASA Earth sciences efforts the MODIS instruments must be and have been carefully calibrated and the performance characterized to meet specifications and goals such as five percent radiance and two percent relative to the sun accuracy in the twenty bands providing reflected solar radiation observations and one percent radiance accuracy in the sixteen bands observing in the thermal infrared. Over the time spanning instrument development and the pre-launch calibration and characterization of the instrument through the years of operation in space, the performance of the MODIS instruments have changed in multiple ways and appropriate adjustments made in relevant algorithms and look-up tables necessary to produce observations that meet the scientific objectives and requirements. The changes have been quantified and accounted for through careful use of on-board calibration devices such as the Spectro-Radiometric Calibration Assembly (SRCA), the Solar Diffuser (SD) and its companion Solar Diffuser Stability Monitor (SDSM), deep-space and lunar observations, and calibration targets on the Earth's surface. The strictest and most difficult challenges have come in trying to meet the requirements for observing Ocean color and related ocean biology processes over time and space. Overall the MODIS observations have been very successful in providing valuable scientific and applications results. The essential capabilities of MODIS are to be provided in the future by the Visible and Infrared Imaging Radiometer Suite (VIIRS) on the National Polar Orbiting Environmental Satellite Series (NPOESS).

  4. Seasonal and Diurnal Tropical Forest Greenness Observed and Modeled Using MODIS Terra and Aqua Sensors

    NASA Astrophysics Data System (ADS)

    Huete, A. R.; Davies, K.; Restrepo-Coupe, N.; Ratana, P.; Sun, Q.; Saleska, S. R.; Schaaf, C.

    2014-12-01

    Recent studies on satellite measures of Amazon forest greening suggest that observed seasonalities are optical artefacts resulting from shifting sun- sensor view geometries between solstice and equinox periods. The degree and extent of sun geometry influences on satellite observations have important implications on the utility of multi-sensor time series for generating accurate long-term data records. Here we investigate sun angle interactions on tropical forest greening using Terra- and Aqua-MODIS, and combined Terra-Aqua Nadir BRDF Adjusted Reflectance (NBAR) vegetation index (VI) time series, with distinct seasonal and daily sun angle conditions for 10:30 a.m., 1:30 p.m. overpasses, and local solar noon times, respectively. This was compared with modeled, sun angle corrected data from the MODIS MCD43A1 product for fixed sun angles. The interactions between sun angle and forest greening were analyzed along an equatorial forest transect of constant sun-earth geometry but variable annual rainfall and dry season length, as well as a latitudinal transect ranging from equatorial to dry southern forests. In equatorial forests, seasonality in sun angle geometry was synchronous with drought seasonality and resulted in broad scale, forest greening consistent with the duration of the dry season and light availability. The sun angle corrected data showed a reduction in the magnitude of seasonal greening, but also revealed an extended greening period well beyond the equinox. On the other hand, across the latitudinal gradient there were shifts in the start and duration of the dry season that resulted in greening patterns that were asynchronous with sun angle geometries. Sun angle influences became significant and were more pronounced at greater latitudes, demonstrating need to normalize cross-sensor satellite data for sun geometry effects, especially with the recent and upcoming launches of new satellite systems.

  5. Multiyear analysis of Terra/Aqua MODIS aerosol optical depth and ground observations over tropical urban region of Hyderabad, India

    NASA Astrophysics Data System (ADS)

    Kharol, Shailesh Kumar; Badarinath, K. V. S.; Sharma, Anu Rani; Kaskaoutis, D. G.; Kambezidis, H. D.

    2011-03-01

    Remote sensing of global aerosols has constituted a great scientific interest in a variety of applications related to global warming and climate change. The present study uses Level 2 (10 × 10 km) and Level 3 (1° × 1°) Terra/Aqua MODIS (C005) derived aerosol optical depths at 550 nm (AOD 550) and compares them with ground-based (MICROTOPS-II, MT) sun photometer measured AOD 550 in the period 2002-2008 over Hyderabad, India. The correlation coefficient ( R2) between Level 3 Terra/Aqua MODIS and MT AOD 550 in all seasons ranges from 0.30 to 0.46. Even lower correlations revealed when the Level 2 MODIS data are used ( R2 = 0.16-0.30). The Level 3 MODIS AOD 550 underestimates significantly the MT AOD 550, while the Level 2 AOD 550 values are much larger than those of Level 3. The comparison of the Terra/Aqua MODIS AOD 550 at regional scale, and especially over urban/industrial areas with significant aerosol diurnal variation, constitutes a real challenge and may reveal the ability of the two sensors to capture the temporal variation of the aerosol loading within a time interval of ˜3 h. The results show relatively good correlation ( R2 ˜ 0.6-0.7) regarding the Level 3 dataset; however, the Level 2 data showed large scatter and very poor correlations. On the other hand, the mean seasonal AOD 550 values are similar, while Terra AOD 550 is higher than that obtained from Aqua. Both satellite and ground-based measurements show remarkable increasing trends in AOD over Hyderabad, which are attributed to the extension of the urbanized area, the growing of population, motor vehicles and local emissions.

  6. NPP VIIRS and Aqua MODIS RSB Comparison Using Observations from Simultaneous Nadir Overpasses (SNO)

    NASA Technical Reports Server (NTRS)

    Xiong, X.; Wu, A.

    2012-01-01

    Suomi NPP (National Polar-orbiting Partnership) satellite (http://npp.gsfc.nasa.gov/viirs.html) began to daily collect global data following its successful launch on October 28, 2011. The Visible Infrared Imaging Radiometer Suite (VIIRS) is a key NPP sensor. Similar to the design of the OLS, SeaWiFS and MODIS instruments, VIIRS has on-board calibration components including a solar diffuser (SD) and a solar diffuser stability monitor (SDSM) for the reflective solar bands (RSB), a V-groove blackbody for the thermal emissive bands (TEB), and a space view (SV) port for background subtraction. Immediately after the VIIRS nadir door s opening on November 21, 2011, anomalously large degradation in the SD response was identified in the near-IR wavelength region, which was unexpected as decreases in the SD reflectance usually occur gradually in the blue (0.4 m) wavelength region based on past experience. In this study, we use a well-calibrated Aqua MODIS as reference to track and evaluate VIIRS RSB stability and performance. Reflectances observed by both sensors from simultaneous nadir overpasses (SNO) are used to determine VIIRS to MODIS reflectance ratios for their spectral matching bands. Results of this study provide an immediate post-launch assessment, independent validation of the anomalous degradation observed in SD measurements at near-IR wavelengths and initial analysis of calibration stability and consistency.

  7. NPP VIIRS and Aqua MODIS RSB comparison using observations from simultaneous nadir overpasses (SNO)

    NASA Astrophysics Data System (ADS)

    Wu, Aisheng; Xiong, Xiaoxiong

    2012-09-01

    Suomi NPP (National Polar-orbiting Partnership) satellite (http://npp.gsfc.nasa.gov/viirs.html) began to daily collect global data following its successful launch on October 28, 2011. The Visible Infrared Imaging Radiometer Suite (VIIRS) is a key NPP sensor. Similar to the design of the OLS, SeaWiFS and MODIS instruments, VIIRS has on-board calibration components including a solar diffuser (SD) and a solar diffuser stability monitor (SDSM) for the reflective solar bands (RSB), a V-groove blackbody for the thermal emissive bands (TEB), and a space view (SV) port for background subtraction. Immediately after the VIIRS nadir door's opening on November 21, 2011, anomalously large degradation in the SD response was identified in the near-IR wavelength region, which was unexpected as decreases in the SD reflectance usually occur gradually in the blue (~0.4 μm) wavelength region based on past experience. In this study, we use a well-calibrated Aqua MODIS as reference to track and evaluate VIIRS RSB stability and performance. Reflectances observed by both sensors from simultaneous nadir overpasses (SNO) are used to determine VIIRS to MODIS reflectance ratios for their spectral matching bands. Results of this study provide an immediate post-launch assessment, independent validation of the anomalous degradation observed in SD measurements at near-IR wavelengths and initial analysis of calibration stability and consistency.

  8. MODIS/Aqua chlorophyll monitoring of the New Caledonia lagoon during the 2008 La Nina event

    NASA Astrophysics Data System (ADS)

    Dupouy, Ccile; Minghelli-Roman, Audrey; Despinoy, Marc; Rttgers, Rudiger; Neveux, Jacques; Pinazo, Christel; Petit, Michel A.

    2009-01-01

    Tropical oligotrophic coral reef lagoons are areas of high biodiversity. Chlorophyll concentration, a proxy for phytoplankton biomass and primary production, is useful to monitor the carbon balance in the context of the climate change and to validate simulations by coupled biogeochemical models. Chlorophyll monitoring by Aqua/MODIS is examined on the large tropical oligo- to mesotrophic lagoon of New Caledonia (23,900 km2). The classical OC3 algorithm developed for MODIS can only be applied in deep waters. In shallow water, when the water is clear with a weak attenuation, the bottom reflectance influences the surface reflectance and then induces an error in the chlorophyll determination. Here, a new OC3-type polynom, relating satellite reflectance ratios and chlorophyll, was determined from bio-optical data collected during a cruise (Valhybio) on the R/V Alis in the frame of the Programme National de Tldtection Spatiale. From the 22th of March to the 9th of April, data were collected during two surveys of the same network. A total of 170 in situ bio-optical measurements in the South Western and South lagoons of New Caledonia were obtained, within a 2 weeks interval (70 non-cloudy match-ups). Four Modis images were acquired during this cruise with moderate to good atmospheric conditions. The new polynom gives a RMS of 14.8% and a MNB of - 9% and gives a better representation of the "true" water column chlorophyll concentration of the New Caledonia lagoon.

  9. MODIS/Aqua chlorophyll monitoring of the New Caledonia lagoon during the 2008 La Nina event

    NASA Astrophysics Data System (ADS)

    Dupouy, Ccile; Minghelli-Roman, Audrey; Despinoy, Marc; Rttgers, Rudiger; Neveux, Jacques; Pinazo, Christel; Petit, Michel A.

    2008-12-01

    Tropical oligotrophic coral reef lagoons are areas of high biodiversity. Chlorophyll concentration, a proxy for phytoplankton biomass and primary production, is useful to monitor the carbon balance in the context of the climate change and to validate simulations by coupled biogeochemical models. Chlorophyll monitoring by Aqua/MODIS is examined on the large tropical oligo- to mesotrophic lagoon of New Caledonia (23,900 km2). The classical OC3 algorithm developed for MODIS can only be applied in deep waters. In shallow water, when the water is clear with a weak attenuation, the bottom reflectance influences the surface reflectance and then induces an error in the chlorophyll determination. Here, a new OC3-type polynom, relating satellite reflectance ratios and chlorophyll, was determined from bio-optical data collected during a cruise (Valhybio) on the R/V Alis in the frame of the Programme National de Tldtection Spatiale. From the 22th of March to the 9th of April, data were collected during two surveys of the same network. A total of 170 in situ bio-optical measurements in the South Western and South lagoons of New Caledonia were obtained, within a 2 weeks interval (70 non-cloudy match-ups). Four Modis images were acquired during this cruise with moderate to good atmospheric conditions. The new polynom gives a RMS of 14.8% and a MNB of - 9% and gives a better representation of the "true" water column chlorophyll concentration of the New Caledonia lagoon.

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

    NASA Technical Reports Server (NTRS)

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

    2015-01-01

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

  11. Status of Aqua MODIS Instrument On-Orbit Operation and Calibration

    NASA Technical Reports Server (NTRS)

    Xiong, Jack; Angal, Amit; Madhaven, Sri; Choi, Jason; Wenny, Brian; Sun, Junqiang; Wu, Aisheng; Chen, Hongda; Salomonson, Vincent; Barnes, William

    2011-01-01

    The Aqua MOderate resolution Imaging Spectroradiometer (MODIS) has successfully operated for nearly a decade, since its launch in May 2002. MODIS was developed and designed with improvements over its heritage sensors in terms of its overall spectral, spatial, and temporal characteristics, and with more stringent calibration requirements. MODIS carries a set of on-board calibrators that can be used to track and monitor its on-orbit radiometric, spectral, and spatial performance. Since launch, extensive instrument calibration and characterization activities have been scheduled and executed by the MODIS Characterization Support Team (MCST). These efforts are made to assure the quality of instrument calibration and L 1B data products, as well as support all science disciplines (land, ocean, and atmospheric) for continuous improvements of science data product quality. MODIS observations from both Terra and Aqua have significantly contributed to the science and user community over a wide range of research activities and applications. This paper provides an overview of Aqua MODIS on-orbit operation and calibration activities, instrument health status, and on-board calibrators (OBC) performance. On-orbit changes of key sensor parameters, such as spectral band radiometric responses, center wavelengths, and bandwidth, are illustrated and compared with those derived from its predecessor, Terra MODIS. Lessons and challenges identified from Aqua MODIS performance are also discussed in this paper. These lessons are not only critical to future improvements of Aqua MODIS on-orbit operation and calibration but also beneficial to its follow-on instrument, the Visible Infrared Imager Radiometer Suite (VIIRS) to be launched on NPOESS Preparatory Project (NPP) spacecraft.

  12. Global Cross-Comparison of Suomi NPP VIIRS Vegetation Index EDR with Aqua MODIS

    NASA Astrophysics Data System (ADS)

    Miura, T.; Tsend-Ayush, J.; Kato, A.; Vargas, M.

    2014-12-01

    The Visible Infrared Imaging Radiometer Suite (VIIRS) sensor series is slated to continue the highly calibrated data stream initiated with Earth Observing System (EOS) Moderate Resolution Imaging Spectroradiometer (MODIS). A number of geophysical products, termed Environmental Data Records (EDRs), are being produced from VIIRS data, including Vegetation Index (VI) EDR. VIIRS VI EDR is a daily, 375 m resolution product and includes the "Top-of-the-Atmosphere (TOA)" Normalized Difference Vegetation Index (NDVI) and the "Top-of-Canopy (TOC)" Enhanced Vegetation Index (EVI). The TOC NDVI is being added to the product. In this study, we cross-compared VI EDR from the first VIIRS sensor onboard the Suomi National Polar-orbiting Partnership (NPP) satellite platform with the Aqua MODIS counterparts in global scale with the aim of developing a thorough understanding of radiometric compatibility between the two VI datasets. VIIRS VI products from April 2014 through June 2014 were obtained along with MODIS daily products. They were all reprojected and spatially-aggregated into a 4 km sinusoidal grid while screening for cloud and aerosol contaminations using quality flags. We then masked VIIRS-MODIS observation pairs for near-identical observation geometry: (1) view zenith angle (VZA) < 7.5 degrees, (2) 20 degrees < VZA < 27.5 degrees, (3) 40 degrees < VZA < 47.5 degrees, and (4) 55 degrees < VZA < 62.5 degrees. Their mean differences (MDs) were computed for each VZA bin and for all bins at once for quantitative evaluation. VIIRS and MODIS TOA NDVI had a very small overall MD of 0.005 NDVI units, whereas TOC EVI had a fairly large overall MD of -0.04 EVI units. These systematic differences were consistent across the 2-month period examined in this study. TOC NDVI, on the other hand, had largely fluctuating MD across this period, ranging from 0.005 to 0.01 NDVI units, an indication of inconsistent atmospheric correction or cloud mask results. With respect to VZA, inconsistent MDs were always obtained for the 55-62.5 degree VZA bin for all the three indices. Overall, VIIRS and MODIS VI products are subject to systematic differences, which are however consistent for VZ < 50 degrees. Future studies should examine the performance of VIIRS atmospheric corrections and compatibility of VIIRS and MODIS observations at large VZA.

  13. On-Orbit Calibration and Performance of Aqua MODIS Reflective Solar Bands

    NASA Technical Reports Server (NTRS)

    Xiong, Xiaoxiong; Sun, Junqiang; Xie, Xiaobo; Barnes, William; Salomonson, Vincent

    2009-01-01

    Aqua MODIS has successfully operated on-orbit for more than 6 years since its launch in May 2002, continuously making global observations and improving studies of changes in the Earth's climate and environment. 20 of the 36 MODIS spectral bands, covering wavelengths from 0.41 to 2.2 microns, are the reflective solar bands (RSB). They are calibrated on-orbit using an on-board solar diffuser (SD) and a solar diffuser stability monitor (SDSM). In addition, regularly scheduled lunar observations are made to track the RSB calibration stability. This paper presents Aqua MODIS RSB on-orbit calibration and characterization activities, methodologies, and performance. Included in this study are characterizations of detector signal-to-noise ratio (SNR), short-term stability, and long-term response change. Spectral wavelength dependent degradation of the SD bidirectional reflectance factor (BRF) and scan mirror reflectance, which also varies with angle of incidence (AOI), are examined. On-orbit results show that Aqua MODIS onboard calibrators have performed well, enabling accurate calibration coefficients to be derived and updated for the Level 1B (L1B) production and assuring high quality science data products to be continuously generated and distributed. Since launch, the short-term response, on a scan-by-scan basis, has remained extremely stable for most RSB detectors. With the exception of band 6, there have been no new RSB noisy or inoperable detectors. Like its predecessor, Terra MODIS, launched in December 1999, the Aqua MODIS visible (VIS) spectral bands have experienced relatively large changes, with an annual response decrease (mirror side 1) of 3.6% for band 8 at 0.412 microns, 2.3% for band 9 at 0.443 microns, 1.6% for band 3 at 0.469 microns, and 1.2% for band 10 at 0.488 microns. For other RSB bands with wavelengths greater than 0.5 microns, the annual response changes are typically less than 0.5%. In general, Aqua MODIS optics degradation is smaller than Terra MODIS and the mirror side differences are much smaller. Overall, Aqua MODIS RSB on-orbit performance is better than Terra MODIS.

  14. Changes in Arctic Diurnal Range Land-Surface Temperature Derived by NASA MODIS-Terra and -Aqua 2000 through 2012

    NASA Astrophysics Data System (ADS)

    Muskett, Reginald

    2015-04-01

    The diurnal variation of surface temperature is a fundamental parameter as it is a driver of physical processes of atmosphere-land and -ocean energy and mass cycles playing a key role in meteorology and climatology. Our investigation focus is on the diurnal variation of land-surface temperature derived by the Moderate Resolution Imaging Spectroradiometer (MODIS) deployed on the NASA Terra and Aqua satellites. We key our investigation on the ascending and descending mode equator crossing times for daytime and nighttime land-surface temperature variations from March 2000 through 2010 (MODIS-Terra) and July 2002 through 2012 (MODIS-Aqua) and assess the diurnal land-surface temperature range changes at those sampling times. Our investigation shows non-stationary changes in land-surface temperature diurnal range. We identify changes in the diurnal range linked to increase of daytime and nighttime land-surface temperatures from March 2000 through 2010 and decrease in daytime and nighttime land-surface temperatures from July 2002 through 2012. The most recent decrease in daytime and nighttime land-surface temperatures and diurnal range will affect Arctic and other associated energy and mass cycles. Ref.: http://www.scirp.org/journal/PaperDownload.aspx?paperID=44731

  15. Arctic Diurnal Land-Surface Temperature Range Changes Derived by NASA MODIS-Terra and -Aqua 2000 through 2012

    NASA Astrophysics Data System (ADS)

    Muskett, R. R.

    2014-12-01

    The diurnal variation of surface temperature is a fundamental parameter as it is a driver of physical processes of atmosphere-land and -ocean energy and mass cycles playing a key role in meteorology and climatology. Our investigation focus is on the diurnal variation of land-surface temperature derived by the Moderate Resolution Imaging Spectroradiometer (MODIS) deployed on the NASA Terra and Aqua satellites. We key our investigation on the ascending and descending mode equator crossing times for daytime and nighttime land-surface temperature variations from March 2000 through 2010 (MODIS-Terra) and July 2002 through 2012 (MODIS-Aqua) and assess the diurnal land-surface temperature range changes at those sampling times. Our investigation shows non-stationary changes in the trends of land-surface temperature diurnal range. We identify changes in the diurnal range trends linked to increase of daytime and nighttime land-surface temperatures from March 2000 through 2010 and decrease in daytime and nighttime land-surface temperatures from July 2002 through 2012. The most recent decrease in daytime and nighttime land-surface temperatures and diurnal range will affect Arctic and other associated energy and mass cycles. Reference: Muskett, R., Atmospheric and Climate Sciences, vol. 4, pp. 231-240, 2014. http://dx.doi.org/10.4236/acs.2014.42026, http://www.scirp.org/journal/PaperDownload.aspx?paperID=44731

  16. Two MODIS Aerosol Products Over Ocean on the Terra and Aqua CERES SSF Datasets

    NASA Technical Reports Server (NTRS)

    Ignatov, Alexander; Minnis, Patrick; Loeb, Norman; Wielicki, Bruce; Miller, Walter; Sun-Mack, Sunny; Tanre, Didier; Remer, Lorraine; Laszlo, Istvan; Geier, Erika

    2004-01-01

    Over ocean, two aerosol products are reported on the Terra and Aqua CERES SSFs. Both are derived from MODIS, but using different sampling and aerosol algorithms. This study briefly summarizes these products, and compares using 2 weeks of global Terra data from 15-21 December 2000, and 1-7 June 2001.

  17. Scene-based cross-comparison of SNPP-VIIRS and Aqua-MODIS over oceanic waters

    NASA Astrophysics Data System (ADS)

    Pahlevan, Nima; Lee, Zhongping; Lawson, Adam; Arnone, Robert

    2013-09-01

    The Visible Infrared Imaging Radiometer Suite (VIIRS) onboard the Suomi National Polar-orbiting Operational Environmental Satellite System (NPOESS) Preparatory Project (NPP) (SNPP) was launched in October 2011 to continue monitoring the globe in a similar fashion as the heritage sensors, such as the MODerate resolution Imaging Spectroradiometer (MODIS). This paper applies a scene-based technique to examine in-orbit radiometric stability of VIIRS relative to Aqua MODIS. The cross-comparison is made over global deep ocean waters. This cross-comparison allows for a comprehensive examination of the sensors' radiometric responsivity at relatively low signal levels (over oceanic waters). The study is further extended to L2/L3 products, including remote sensing reflectance and the inherent optical properties (IOPs) of waters under investigation, derived from the top-of-atmosphere (TOA) radiance (L1B). The temporal analyses give insights into the trends in the relative radiometric stability and the resulting discrepancies in the corresponding products.

  18. Evaluating the impact of cold focal plane temperature on Aqua MODIS thermal emissive band calibration

    NASA Astrophysics Data System (ADS)

    Li, Yonghong; Wu, Aisheng; Wenny, Brian; Xiong, Xiaoxiong

    2015-09-01

    Aqua MODIS, the second MODIS instrument of the NASA Earth Observation System, has operated for over thirteen years since launch in 2002. MODIS has sixteen thermal emissive bands (TEB) located on two separate cold focal plane assemblies (CFPA). The TEB are calibrated using onboard blackbody and space view observations. MODIS CFPA temperature is controlled by a radiative cooler and heaters in order to maintain detector gain stability. Beginning in 2006, the CFPA temperature gradually varies from its designed operating temperature with increasing orbital and seasonal fluctuations, with the largest observed impacts on the TEB photoconductive (PC) bands. In Aqua Collection 6 (C6), a correction to the detector gain due to the CFPA temperature variation is applied for data after mid-2012. This paper evaluates the impact of the CFPA temperature variation on the TEB PC band calibration through comparisons with simultaneous nadir overpasses (SNO) measurements from the Infrared Atmospheric Sounding Interferometer (IASI) and Atmospheric Infrared Sounder (AIRS). Our analysis shows that the current L1B product from mid-2011 to mid-2012 is affected by the CFPA temperature fluctuation. The MODIS-IASI comparison results show that no drift is observed in PC bands over the CFPA temperature variation range. Similarly, in the MODIS-AIRS comparison, bands 31-34 show nearly no trend over the range of CFPA temperature while a slight drift in bands 35-36 are seen from the comparison results.

  19. An Overview of Inter-comparison Methodologies for Terra and Aqua MODIS Calibration

    NASA Technical Reports Server (NTRS)

    Xiong, X.; Wu, A.; Sun, J.

    2006-01-01

    With increasing efforts on data fusion and long-term climate data records (CDR) using observations made by multiple sensors, on the same or different platforms, their cross-calibration and validation work has become more and more important. The uncertainties of the climate models and data records depend not only on the calibration quality of individual sensors but also on their calibration consistency. This paper provides an overview of methodologies used by the MODIS Characterization Support Team (MCST) at NASA GSFC for the inter-comparison studies of Terra and Aqua MODIS on-orbit calibration. Each MODIS was built with a set of onboard calibrators (OBC) that include a blackbody (BB), a solar diffuser (SD), and a solar diffuser stability monitor (SDSM). The BB is primarily used for the thermal emissive bands (TEB) calibration and the SD/SDSM system for the reflective solar bands (RSB) calibration. Although the-instrument design and calibration approach are nearly identical for both Terra and Aqua MODIS and they all went through an extensive and similar pre-launch calibration and characterization process, still their on-orbit calibration consistency needs to be carefully examined and validated as many science products have been generated from observations made by both instruments. Methodologies discussed in this paper include inter-comparison studies using the Moon, a third sensor, and ground targets. Our results show that Terra and Aqua reflective solar bands and thermal emissive bands have been calibrated consistently with excellent long-term stabilities. For the 11 and 12 micrometers sea surface temperature (SST) bands, the calibration difference of Terra and Aqua MODIS is less than 0.2K.

  20. A fast and robust implementation of the adaptive destriping algorithm for SNPP VIIRS and Terra/Aqua MODIS SST

    NASA Astrophysics Data System (ADS)

    Mikelsons, Karlis; Ignatov, Alexander; Bouali, Marouan; Kihai, Yury

    2015-05-01

    Radiometric performance of MODIS and VIIRS sensors is superior to that of the AVHRR, thanks to improved design and implementation of stringent pre-launch sensor characterization efforts and in-flight monitoring practices. Nevertheless, the imagery of the measured brightness temperatures (BT) and derived sea surface temperatures (SST) from multi-detector MODIS and VIIRS instruments is subject to striping artifacts. A robust adaptive destriping algorithm recently introduced by Bouali and Ignatov1 was optimized and operationally implemented at NOAA to remove striping artifacts in the VIIRS BT data. Destriped BTs are used as input into the NOAA Advanced Clear-Sky Processor for Oceans (ACSPO) SST system. The algorithm is also run with MODIS data onboard Terra/Aqua, in an experimental mode. We demonstrate improved image quality of VIIRS and MODIS BTs in bands centered at 3.7, 11 and 12 μm, and significant improvements in the derived SST imagery. The algorithm proves capable of removing the striping noise, while preserving the fine natural contrasts of the original satellite imagery. It was also tested to remove striping artifacts from the VIIRS and MODIS "optional SST" bands, centered at 4 and 8.5 μm. Destriping is critically important for several SST applications relying on accurate BT or SST gradient data, including ocean front detection and pattern recognition improvements to ACSPO cloud mask. We present the results of statistical characterization of striping artifacts in the VIIRS and MODIS thermal IR bands under various observational conditions. Our implementation of destriping is computationally efficient, adding only a fraction of time to the SST data processing flow. It is currently used at NOAA with VIIRS operations and reprocessing efforts.

  1. An initial assessment of the VIIRS onboard calibration using DCC and desert referenced to the Aqua-MODIS calibration

    NASA Astrophysics Data System (ADS)

    Bhatt, Rajendra; Doelling, David R.; Scarino, Benjamin R.; Gopalan, Arun; Haney, Conor O.

    2013-09-01

    The CERES observed EBAF 12-year TOA flux dataset are used to monitor the Earth's climate and in validating climate models. The associated cloud properties are retrieved from a fusion of MODIS and geostationary imagers. The quality of these cloud properties relies on the absolute calibration of these imagers. The geostationary imager radiances are calibrated against the Aqua-MODIS calibration reference in order to retrieve uniform cloud properties both spatially and temporally. Any calibration discontinuity or artifact may be interpreted as a climate trend. CERES record will be extended using CERES fluxes onboard NPP. CERES will need to tie the VIIRS with the Aqua-MODIS calibration in order to provide a seamless record of cloud and flux properties. This paper will present initial assessment results for interconsistency between VIIRS and Aqua-MODIS calibration of matching visible channels. Empirically derived exoatmospheric VIIRS radiance models for deep convective clouds and deserts invariant targets are used to assess the initial onboard calibration of VIIRS. The VIIRS models are based on characterizing these invariant targets with Aqua-MODIS as an absolute calibration reference in order to tie the VIIRS calibration to Aqua-MODIS. Correction for spectral band differences in the VIIRS and MODIS channels is performed using the SCIAMACHY hyperspectral data.

  2. Decadal changes of water properties in the Aral Sea observed by MODIS-Aqua

    NASA Astrophysics Data System (ADS)

    Shi, Wei; Wang, Menghua

    2015-07-01

    Twelve-year satellite observations between 2002 and 2013 from the Moderate Resolution Imaging Spectroradiometer (MODIS) onboard the satellite Aqua are used to quantitatively assess the water property changes in the Aral Sea. The shortwave infrared (SWIR) atmospheric correction algorithm is required and used to derive normalized water-leaving radiance spectra nLw(λ) in the Aral Sea. We used radiance ratio nLw(555)/nLw(443) as a surrogate to characterize the spatial and temporal variations of chlorophyll-a (Chl-a) in the Aral Sea. Both seasonal variability and significant interannual changes were observed when the Aral Sea desiccated between 2002 and 2013. All three separated regions of the Aral Sea show increased nLw(555)/nLw(443) ratio (a surrogate for Chl-a) and the diffuse attenuation coefficient at the wavelength of 490 nm (Kd(490)) during the fall season. Of the three regions, the North Aral Sea has had the least interannual variability, while South-East (SE) Aral Sea experienced drastic changes. Waters in the SE Aral Sea are the most turbid with significantly higher Kd(490) than those in the other two subregions. Kd(490) gradually increased from ˜2 m-1 in 2002 to ˜3.5 m-1 after 2008 in the SE Aral Sea. In comparison, both radiance ratio nLw(555)/nLw(443) and Kd(490) were relatively stable for the North Aral Sea. In the South-West (SW) Aral Sea, however, nLw(555)/nLw(443) values reached peaks in the fall of 2007 and 2010. A possible link between the Aral Sea water property change and the regional climate variation is also discussed.

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

    PubMed

    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

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

    PubMed

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

    2012-10-15

    This paper describes the use of ocean color remote sensing data from the Moderate Resolution Imaging Spectroradiometer (MODIS) onboard the Aqua satellite to characterize turbidity in Lake Okeechobee and its primary drainage basins, the Caloosahatchee and St. Lucie estuaries from 2002 to 2010. Drainage modification and agricultural development in southern Florida transport sediments and nutrients from watershed agricultural areas to Lake Okeechobee. As a result of development around Lake Okeechobee and the estuaries that are connected to Lake Okeechobee, estuarine conditions have also been adversely impacted, resulting in salinity and nutrient fluctuations. The measurement of water turbidity in lacustrine and estuarine ecosystems allows researchers to understand important factors such as light limitation and the potential release of nutrients from re-suspended sediments. Based on a strong correlation between water turbidity and normalized water-leaving radiance at the near-infrared (NIR) band (nL(w)(869)), a new satellite water turbidity algorithm has been developed for Lake Okeechobee. This study has shown important applications with satellite-measured nL(w)(869) data for water quality monitoring and measurements for turbid inland lakes. MODIS-Aqua-measured water property data are derived using the shortwave infrared (SWIR)-based atmospheric correction algorithm in order to remotely obtain synoptic turbidity data in Lake Okeechobee and normalized water-leaving radiance using the red band (nL(w)(645)) in the Caloosahatchee and St. Lucie estuaries. We found varied, but distinct seasonal, spatial, and event driven turbidity trends in Lake Okeechobee and the Caloosahatchee and St. Lucie estuary regions. Wind waves and hurricanes have the largest influence on turbidity trends in Lake Okeechobee, while tides, currents, wind waves, and hurricanes influence the Caloosahatchee and St. Lucie estuarine areas. PMID:22858282

  5. Recent Progress on Cross-Comparison of Terra and Aqua MODIS Calibration Using Dome C

    NASA Technical Reports Server (NTRS)

    Xiong, X.; Wu, A.; Angal, A.; Wenny, B.

    2009-01-01

    For the past few years, the MODIS Characterization Support Team (MCST) at NASA/GSFC has continued to evaluate the Terra and Aqua MODIS calibration long-term stability and their calibration consistency using sensor observations over the Dome Concordia, Antarctica. Early results from Dome C observations show that the calibration of bands I and 2 (0.65 and 0.86 micron) is consistent within 1-2% and bands 31 and 32 (11 and 12 micron) differences are less than a couple of tenths of Kelvin, demonstrating that this site can provide a useful calibration reference for a wide range of Earth-observing sensors from visible (VIS) to long-wave infrared (LWIR). Recently, the Dome C area has been endorsed by the CEOS as a reference standard site for sensor cross-comparison. This, as a result, has led to an invitation to the broad community to participate in a CEOS comparison of top-of-atmosphere (TOA) spectral radiance/reflectance over Dome C. In this paper, we provide a brief description of the methodologies and report our recent progress on cross-comparison of Terra and Aqua MODIS spectral bands using observations over this area, including data provided in support of the upcoming CEOS comparison. Emphasis of this paper is on the long-term data records of MODIS instruments, their calibration consistency, and challenging issues.

  6. Urban vegetation land covers change detection using multi-temporal MODIS Terra/Aqua data

    NASA Astrophysics Data System (ADS)

    Zoran, Maria A.; Savastru, Roxana S.; Savastru, Dan M.; Dida, Adrian I.; Ionescu, Ovidiu M.

    2013-10-01

    Urban vegetation land cover change is a direct measure of quantitative increase or decrease in sources of urban pollution and the dimension of extreme climate events and changes that determine environment quality. Spatio- temporal monitoring of urban vegetation land cover changes is a very important task for establishing the links between policy decisions, regulatory actions and subsequent land use activities. Former studies incorporating two-date change detection using Landsat TM/ETM data had limited performance for urban biophysically complex systems applications. In this paper, we describe recent results using data from NASA's Moderate Resolution Imaging Spectroradiometer and NOAA/AVHRR satellite to study urban vegetation land cover dynamics. This study explored the use of time-series MODIS Terra/Aqua Normalized Difference Vegetation Index (NDVI) and Leaf Area Index (LAI), data to provide change detection information for metropolitan area of Bucharest in Romania. Training and validation are based on a reference dataset collected from IKONOS high resolution remote sensing data. The mean detection accuracy for period 2002- 2012 was assessed to be of 89%, with a reasonable balance between change commission errors (21.7%), change omission errors (28.5%), and Kappa coefficient of 0.69. Annual change detection rates across the urban/periurban areas over the study period (2002-2012) were estimated at 0.78% per annum in the range of 0.45% (2002) to 0.75% (2012).Vegetation dynamics in urban areas at seasonal and longer timescales reflect large-scale interactions between the terrestrial biosphere and the climate system.

  7. Consistency of Global Modis Aerosol Optical Depths over Ocean on Terra and Aqua Ceres SSF Datasets

    NASA Technical Reports Server (NTRS)

    Ignatov, Alexander; Minnis, Patrick; Miller, Walter F.; Wielicki, Bruce A.; Remer, Lorraine

    2006-01-01

    Aerosol retrievals over ocean from the Moderate Resolution Imaging Spectroradiometer (MODIS) onboard Terra and Aqua platforms are available from the Clouds and the Earth's Radiant Energy System (CERES) Single Scanner Footprint (SSF) datasets generated at NASA Langley Research Center (LaRC). Two aerosol products are reported side-by-side. The primary M product is generated by sub-setting and remapping the multi-spectral (0.47-2.1 micrometer) MODIS produced oceanic aerosol (MOD04/MYD04 for Terra/Aqua) onto CERES footprints. M*D04 processing uses cloud screening and aerosol algorithms developed by the MODIS science team. The secondary AVHRR-like A product is generated in only two MODIS bands 1 and 6 (on Aqua, bands 1 and 7). The A processing uses the CERES cloud screening algorithm, and NOAA/NESDIS glint identification, and single-channel aerosol retrieval algorithms. The M and A products have been documented elsewhere and preliminarily compared using 2 weeks of global Terra CERES SSF Edition 1A data in which the M product was based on MOD04 collection 3. In this study, the comparisons between the M and A aerosol optical depths (AOD) in MODIS band 1 (0.64 micrometers), tau(sub 1M) and tau(sub 1A) are re-examined using 9 days of global CERES SSF Terra Edition 2A and Aqua Edition 1B data from 13 - 21 October 2002, and extended to include cross-platform comparisons. The M and A products on the new CERES SSF release are generated using the same aerosol algorithms as before, but with different preprocessing and sampling procedures, lending themselves to a simple sensitivity check to non-aerosol factors. Both tau(sub 1M) and tau(sub 1A) generally compare well across platforms. However, the M product shows some differences, which increase with ambient cloud amount and towards the solar side of the orbit. Three types of comparisons conducted in this study - cross-platform, cross-product, and cross-release confirm the previously made observation that the major area for improvement in the current aerosol processing lies in a more formalized and standardized sampling (and most importantly, cloud screening) whereas optimization of the aerosol algorithm is deemed to be an important yet less critical element.

  8. Identifying false rain in satellite precipitation products using CloudSat and MODIS

    NASA Astrophysics Data System (ADS)

    Nasrollahi, N.; Hsu, K.; Sorooshian, S.

    2012-12-01

    Moderate Resolution Imaging Spectroradiometer (MODIS) instrument on board NASA Earth Observing System Aqua and Terra platform with 36 spectral bands provides valuable information about cloud microphysical characteristics. Additionally, CloudSat, selected as a NASA Earth Sciences Systems Pathfinder (ESSP) satellite mission, is designed to measure vertical structure of clouds. The CloudSat radar flies in formation with Aqua with only an average of 60 second delay. In this study, the application of MODIS multispectral images and CloudSat Level 2-C Precipitation Column Algorithm in false rain identification is investigated. Using a machine learning technique, the presence of precipitation will be assigned to textural and spectral features of clouds observed by the MODIS satellite, whenever CloudSat surface rainfall retrieval is available. This information for different regions and seasons create a training data set. The training database will then be used as a reference to find if any pixel in the MODIS retrieval window is falsely identified as rainy pixel for the times that CloudSat data is not available. The input to the Artificial Neural Networks (ANN) model is a combination of 8 MODIS visible, water vapor and infrared channels. The performance of model with combination of different MODIS channels is estimated. The results of ANN model are used to filter out false rainy pixels from satellite precipitation estimates (e.g. PERSIANN). The outcome of the new corrected precipitation data is compared to ground based radar measurements (Stage IV radar data). The results show a 64 percent reduction in false rain in PERSIANN satellite data for 100 cases investigated in summer 2008 and 24 percent false rain reduction in more than 50 cases studied in winter 2010.

  9. Terra and Aqua MODIS on-orbit spectral characterization for reflective solar bands

    NASA Astrophysics Data System (ADS)

    Choi, Taeyoung (Jason); Xiong, Xiaoxiong (Jack); Wang, Zhipeng; Link, Daniel

    2013-06-01

    The MODerate resolution Imaging Spectroradiometers (MODIS) onboard the NASA EOS Terra and Aqua spacecraft were launched on December 18, 1999 and May 4, 2002 respectively. They have both successfully operated on-orbit for more than a decade. The spectral characteristics of the MODIS instruments were calibrated pre-launch using a ground calibration device called the Spectral Measurement Assembly (SpMA). The ground spectral characterization was transferred to an on-board device called the Spectro-Radiometric Calibration Assembly (SRCA) for the Reflective Solar Bands (RSB) by measuring the sensor spectral responses near simultaneously with both SRCA and SpMA. After transferring the calibration reference from the SpMA, the SRCA was able to track the on-orbit spectral changes by performing periodic spectral mode operations. This paper provides brief descriptions of MODIS on-orbit spectral characterization via its on-board SRCA. In the algorithm description section, functional steps and spectral calibration methodologies are presented. This study will focus on MODIS SWIR bands (bands 5, 6, 7 and 26) as their center wavelengths are longer than 1μm, which is beyond the specified SRCA spectral calibration range. In addition to the SWIR bands, band 2 results are also included. Because of the pre-launch and on-orbit configuration differences, band 2 spectral characterization is referenced to the first onorbit results. A summary of Terra and Aqua MODIS on-orbit relative spectral response changes, such as center wavelength and bandwidth changes, is provided in this paper for all the RSB bands.

  10. Monitoring the Terra and Aqua MODIS RSB calibration using scattered light from the Nadir-port

    NASA Astrophysics Data System (ADS)

    Angal, Amit; Xiong, Xiaoxiong; Geng, Xu; Sun, Junqiang

    2014-09-01

    MODIS is currently onboard NASA's EOS Terra and Aqua spacecraft launched on December 18, 1999 and May 4, 2002, respectively. MODIS reflective solar bands (RSB) are calibrated on-orbit using solar illumination reflected from its onboard solar diffuser (SD). The solar diffuser stability monitor (SDSM) is designed to track the on-orbit degradation of the SD via alternate observations of the Sun and SD. A wavelength-dependent degradation pattern is observed for both MODIS instruments with a faster degradation rate observed at shorter wavelengths. The UV exposure of the SD to sunlight and the scattered light (the sunlight reflected from top of the atmosphere) through the instrument nadir port contributes to its reflectance degradation. The scatter off the diffuser onto the scan mirror is in the forward direction, whereas the scatter off the diffuser onto the SDSM scan mirror is in the backward direction. Since the outgoing angles (viewed by MODIS detectors) are the same as the scheduled SD calibration, the gain derived from scattering light facilitates monitoring the dependence on SD degradation on incident angles. A methodology is formulated to track the MODIS SD degradation using scattered light through the nadir-port and comparing the result with the SD degradation as measured by the SDSM. In this study, multiple orbits from a given day of each month are processed to obtain a SD response to the nadir-port illumination. Results show that a reasonable agreement is observed between the SD degradation estimates derived from both view-angles.

  11. Ocean Color Data at the Goddard Earth Sciences (GES) DAAC: CZCS, SeaWiFS, OCTS, MODIS-Terra, MODIS-Aqua

    NASA Technical Reports Server (NTRS)

    2002-01-01

    The Goddard Earth Sciences Distributed Active Archive Center (DAAC) is the designated archive for all of the ocean color data produced by NASA satellite missions. The DAAC is a long-term, high volume, secure repository for many different kinds of environmental data. With respect to ocean color, the Goddard DAAC holds all the data obtained during the eight-year mission of the Coastal Zone Color Scanner (CZCS). The DAAC is currently receiving data from the Sea-viewing Wide Field-of-view Sensor (SeaWiFS), and the MODIS-Terra instrument. The DAAC recently received reformatted data from the Ocean Color and Temperature Scanner (OCTS) and will also archive MODIS-Aqua Ocean products. In addition to its archive and distribution services, the Goddard DAAC strives to improve data access, ease-of-use, and data applicability for a broad spectrum of customers. The DAAC's data support teams practice dual roles, both insuring the integrity of the DAAC data archive and serving the user community with answers to user inquiries, online and print documentation, and customized data services.

  12. Investigating Enhanced Aqua MODIS Aerosol Optical Depth Retrievals over the Mid-to-high Latitude Southern Oceans Through Intercomparison with Co-located CALIOP, MAN, and AERONET Data Sets

    NASA Technical Reports Server (NTRS)

    Toth, Travis D.; Zhang, Jianglong; Campbell, James R.; Reid, Jeffrey S.; Shi, Yingxi; Johnson, Randall S.; Smirnov, Alexander; Vaughan, Mark A.; Winker, David M.

    2013-01-01

    A band of enhanced aerosol optical depth (AOD) over the mid-to-high latitude Southern Oceans exists in some passive satellite-based aerosol data sets, including Moderate Resolution Imaging Spectroradiometer (MODIS) products. Past studies suggest several potential causes contributing to this phenomenon, including signal uncertainty, retrieval bias, and cloud contamination. In this paper, quality-assured Aqua MODIS aerosol products in this zonal band are investigated to assess cloud contamination as a cause. Spatially and temporally collocated cloud and aerosol products produced by the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) project relative to Aqua MODIS AOD in this region are considered. Maritime Aerosol Network (MAN) and Aerosol Robotic Network (AERONET) AOD data are also collocated with Aqua MODIS retrievals for surface context. The results of this study indicate that the high Aqua MODIS AOD are not seen in the CALIOP aerosol products, cannot be screened using active profiling of collocated observations for cloud presence, and are not detected by ground-based observations such as MAN and AERONET. Enhanced AOD values are attributable primarily to stratocumulus and low broken cumulus cloud contamination, as identified with CALIOP products. But these clouds explain only about 30-40% of the total anomaly. Cirrus cloud contamination is also a factor. However, in contrast to the rest of the globe, they contribute less overall, relative to low-level liquid water clouds, which are considered likely the result of misidentification of relatively warm cloud tops compared with surrounding open seas.

  13. Evaluation of Terra and Aqua MODIS thermal emissive band response versus scan angle

    NASA Astrophysics Data System (ADS)

    Wenny, B. N.; Wu, A.; Madhavan, S.; Xiong, X.

    2014-10-01

    Terra and Aqua MODIS have operated near-continuously for over 14 and 12 years, respectively, and are key instruments for NASA's Earth Observing System. Observations from the 16 thermal emissive bands (TEB), covering wavelengths from 3.5 to 14.4 μm with a nadir spatial resolution of 1 km are used to regularly generate a variety of atmosphere, ocean and land science products. The TEB detectors are calibrated using scan-by-scan observations of an on-board blackbody (BB). The current response versus scan angle (RVS) of the scan mirror was derived using a spacecraft deep-space pitch maneuver for Terra MODIS and characterized during prelaunch for Aqua MODIS. Earth view (EV) data over the complete range of angles of incidence (AOI) can be used to evaluate the on-orbit performance of the TEB RVS over the mission lifetime. Three approaches for tracking the TEB RVS on-orbit using EV observations are formulated. The first approach uses the multiple daily observations of Dome C BT at different AOI and their trend relative to coincident measurements from a ground temperature sensor. The second approach uses brightness temperatures (BT) retrieved over the cloud-free ocean to derive the trends at 13 AOI over the mission lifetime. The third approach tracks the dn response (normalized to the BB AOI) across the full swath width for Antarctic granules with the Dome C site at nadir. The viability of the three approaches is assessed and the long-term stability of the TEB RVS for both MODIS instruments is determined.

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

    NASA Astrophysics Data System (ADS)

    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 precipitation data were analyzed in the drainage area of the GC to consider the potential fluvial sedimentary contribution. The precipitation data was obtained from the TRMM (Tropical Rain Measuring Mission) satellite, and the digital elevation model for the drainage area was generated by use of the SRTM (Shuttle Radar Topography Mission) elevation data. Additionally, thematic cartography 1:250000-scale was used to show the relationship between the type and use of land-cover contrasted against the possible types of sediments entering the GC, wherein gradients of fluvial sedimentary contribution were identified. The terrigenous contribution via resuspension, eolic and fluvial discharges from the drainage basin of the GC is such that makes possible to monitor the surface circulation structures using remote sensors by means of the SPM-like tracers, which also allows us to infer transportation vectors and potential end-deposition of particulates. In order to validate the results of the images, the lagrangian trajectory data collected by researches from CICESE (Ensenada Center for Higher Education Scientific Research) was used. This data was collected by means of distributed drifting buoys throughout the GC. In general, the trajectories of the buoys agree with the structures identified by the images, although the images demonstrate transportation flows from the continental coast towards the peninsular one, especially from the mouth of the River Fuerte whose soils are used for agriculture, so that could transport large concentrations of pesticides across the GC. The gyres detected in the northern portion of the GC along with drifting of the buoys, were also examined in the MODIS images, and their spatial resolution showed several small-scale gyres located throughout the coastal region of Baja California.

  15. Comparison of Terra and Aqua MODIS VIS Bands On-Orbit Response

    NASA Technical Reports Server (NTRS)

    Xiong, Xiaoxiong; Sun, J.; Che, N.; Choi, T.; Angal, A.

    2008-01-01

    The Moderate Resolution Imaging Spectroradiometer (MODIS) has 36 spectral bands with a total of 490 detectors, covering spectral regions in the visible (VIS), near-infrared (NIR), short-wave infrared (SWIR), mid-wave infrared (MWIR), and long-wave infrared (LWIR). MODIS is a cross-track scanning radiometer which collects data using a rotating scan mirror (both sides) over a wide range of scan angles. The VIS, NIR, and SWIR bands (bands 1-19 and 26) make measurements of daytime surface reflected radiances, thus are referred to as the reflective solar bands (RSB). MODIS was built with a complete set of on-board calibrators, capable of providing radiometric, spatial, and spectral calibration and characterization during its entire mission. The RSB on-orbit calibration is primarily provided using a solar diffuser (SD) and a solar diffuser stability monitor (SDSM). The SD and SDSM calibration system is operated on a regular (weekly to bi-weekly) basis. The spectro-radiometric calibration assembly (SRCA) is another on-hoard calibrator that also provides RSB radiometric calibration support. For this purpose, the SRCA is operated in a radiometric mode on a monthly basis. A complete SRCA radiometric calibration is performed using different lamp configurations, or different radiance levels, to cover the range of RSB gain. Two additional SRCA modes with slightly different configurations are designed and operated for sensor on-orbit spectral and spatial characterization. In addition to its on-hoard calibrators, each MODIS makes monthly lunar observations to monitor RSB radiometric calibration stability. The MODIS lunar observations are made through its space view (SV) port at nearly the same lunar phase angles via spacecraft roll maneuvers. The SD, SRCA, and lunar measurements are made at different scan angles and data samples are collected for all spectral bands and detectors using both sides of the scan minor. Since launch, Terra and Aqua MODIS have operated successfully for more than 8 years and 6 years, respectively. Many SD/SDSM, SRCA, and lunar observations have been made by each instrument and used to derive RSB on-orbit calibration parameters, enabling corrections for sensor response changes and changes of the response versus scan angle (RVS). In general, the RSB calibration parameters are updated regularly into the MODIS Level 1B (LIB) code in support of continuous data processing for all MODIS science data products. This paper provides a brief description of MODIS RSB calibration methodologies and approaches, and summarizes on-orbit changes of their responses (gains), particularly for the VIS spectral bands.

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

    NASA Astrophysics Data System (ADS)

    Duan, Hongtao; Feng, Lian; Ma, Ronghua; Zhang, Yuchao; Loiselle, Steven Arthur

    2014-08-01

    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.

  17. Accuracy Assessment of Aqua-MODIS Aerosol Optical Depth Over Coastal Regions: Importance of Quality Flag and Sea Surface Wind Speed

    NASA Technical Reports Server (NTRS)

    Anderson, J. C.; Wang, J.; Zeng, J.; Petrenko, M.; Leptoukh, G. G.; Ichoku, C.

    2012-01-01

    Coastal regions around the globe are a major source for anthropogenic aerosols in the atmosphere, but the underlying surface characteristics are not favorable for the Moderate Resolution Imaging Spectroradiometer (MODIS) algorithms designed for retrieval of aerosols over dark land or open-ocean surfaces. Using data collected from 62 coastal stations worldwide from the Aerosol Robotic Network (AERONET) from approximately 2002-2010, accuracy assessments are made for coastal aerosol optical depth (AOD) retrieved from MODIS aboard Aqua satellite. It is found that coastal AODs (at 550 nm) characterized respectively by the MODIS Dark Land (hereafter Land) surface algorithm, the Open-Ocean (hereafter Ocean) algorithm, and AERONET all exhibit a log-normal distribution. After filtering by quality flags, the MODIS AODs respectively retrieved from the Land and Ocean algorithms are highly correlated with AERONET (with R(sup 2) is approximately equal to 0.8), but only the Land algorithm AODs fall within the expected error envelope greater than 66% of the time. Furthermore, the MODIS AODs from the Land algorithm, Ocean algorithm, and combined Land and Ocean product show statistically significant discrepancies from their respective counterparts from AERONET in terms of mean, probability density function, and cumulative density function, which suggest a need for future improvement in retrieval algorithms. Without filtering with quality flag, the MODIS Land and Ocean AOD dataset can be degraded by 30-50% in terms of mean bias. Overall, the MODIS Ocean algorithm overestimates the AERONET coastal AOD by 0.021 for AOD less than 0.25 and underestimates it by 0.029 for AOD greater than 0.25. This dichotomy is shown to be related to the ocean surface wind speed and cloud contamination effects on the satellite aerosol retrieval. The Modern Era Retrospective-Analysis for Research and Applications (MERRA) reveals that wind speeds over the global coastal region 25 (with a mean and median value of 2.94 meters per second and 2.66 meters per second, respectively) are often slower than 6 meters per second assumed in the MODIS Ocean algorithm. As a result of high correlation (R(sup 2) greater than 0.98) between the bias in binned MODIS AOD and the corresponding binned wind speed over the coastal sea surface, an empirical scheme for correcting the bias of AOD retrieved from the MODIS Ocean algorithm is formulated and is shown to be effective over the majority of the coastal AERONET stations, and hence can be used in future analysis of AOD trend and MODIS AOD data assimilation.

  18. Evaluation of cloud base height measurements from Ceilometer CL31 and MODIS satellite over Ahmedabad, India

    NASA Astrophysics Data System (ADS)

    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.

  19. Analysis of the influence of river discharge and wind on the Ebro turbid plume using MODIS-Aqua and MODIS-Terra data

    NASA Astrophysics Data System (ADS)

    Fernández-Nóvoa, D.; Mendes, R.; deCastro, M.; Dias, J. M.; Sánchez-Arcilla, A.; Gómez-Gesteira, M.

    2015-02-01

    The turbid plume formed at many river mouths influences the adjacent coastal area because it transports sediments, nutrients, and pollutants. The effects of the main forcings affecting the Ebro turbid plume were analyzed using data obtained from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor onboard the Aqua and Terra satellites over the period 2003-2011. Composite images were obtained for days under certain river discharge conditions (different flow regimes) and different types of wind (alongshore and cross-shore winds) in order to obtain a representative plume pattern for each situation. River discharge was the main driver of the Ebro River plume, followed by wind as the secondary force and regional oceanic circulation as the third one. Turbid plume extension increased monotonically with increased river discharge. Under high river discharge conditions (> 355 m3 s- 1), wind distributed the plume in the dominant wind direction. Seaward winds (mistral) produced the largest extension of the plume (1893 km2), whereas southern alongshore winds produced the smallest one (1325 km2). Northern alongshore winds induced the highest mean turbid value of the plume, and southern alongshore winds induced the lowest one. Regardless of the wind condition, more than 70% of the plume extension was located south of the river mouth influenced by the regional oceanic circulation.

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

    NASA Technical Reports Server (NTRS)

    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.

  1. Patterns and connections between aerosols, clouds and vegetation in the Amazon as seen by the twin MODIS sensors aboard Terra and Aqua

    NASA Astrophysics Data System (ADS)

    Meskhidze, N.; Negrón Juárez, R.; Remer, L.; Platnick, S.; Aiyyer, A.

    2007-12-01

    In this study, twin Moderate Resolution Imaging Spectroradiometer (MODIS) sensors aboard NASA's Terra and Aqua satellites are used for characterization of cloud development and identification of processes affecting cloud formation. We find that much of the development of microphysical properties of water clouds over the Brazilian Legal Amazon can be characterized by the simple difference between those properties observed at the two times of MODIS overpass, only 3 hours apart. The time window is small enough that observed differences in cloud properties are primarily associated with the local events; therefore, it is ideal for exploring the effects of plant transpiration, biomass burning and Secondary Organic Aerosol (SOA) formation on regional cloud properties. In this region we find that the effective cloud droplet radius observed in the afternoon by Aqua-MODIS is systematically higher than the effective radii observed in the morning by Terra-MODIS. The difference corresponds to the invigoration of convection in the afternoon with the corresponding growth of droplet size. The monthly mean difference is 1 to 2 um, depending on season, but the overall pattern of the difference prevails throughout the Amazon, is repeated over other tropical rain forest regions globally, and is strikingly different from other types of cloud systems around the globe. Furthermore, we find that the effective radius difference found in the Amazon is inversely correlated to measures of evapotranspiration and all-sky solar radiation at the surface, but is not well-correlated to precipitation. The picture that emerges is a complex one that intertwines a light- limited forest, aerosols (both biogenic and anthropogenic) and cloud development.

  2. Surveillance of waste disposal activity at sea using satellite ocean color imagers: GOCI and MODIS

    NASA Astrophysics Data System (ADS)

    Hong, Gi Hoon; Yang, Dong Beom; Lee, Hyun-Mi; Yang, Sung Ryull; Chung, Hee Woon; Kim, Chang Joon; Kim, Young-Il; Chung, Chang Soo; Ahn, Yu-Hwan; Park, Young-Je; Moon, Jeong-Eon

    2012-09-01

    Korean Geostationary Ocean Color Imager (GOCI) and Moderate Resolution Imaging Spectroradiometer (MODIS) Aqua observations of the variation in ocean color at the sea surface were utilized to monitor the impact of nutrient-rich sewage sludge disposal in the oligotrophic area of the Yellow Sea. MODIS revealed that algal blooms persisted in the spring annually at the dump site in the Yellow Sea since year 2000 to the present. A number of implications of using products of the satellite ocean color imagers were exploited here based on the measurements in the Yellow Sea. GOCI observes almost every hour during the daylight period, every day since June 2011. Therefore, GOCI provides a powerful tool to monitor waste disposal at sea in real time. Tracking of disposal activity from a large tanker was possible hour by hour from the GOCI timeseries images compared to MODIS. Smaller changes in the color of the ocean surface can be easily observed, as GOCI resolves images at smaller scales in space and time in comparison to polar orbiting satellites, e.g., MODIS. GOCI may be widely used to monitor various marine activities in the sea, including waste disposal activity from ships.

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

    NASA Technical Reports Server (NTRS)

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

    2015-01-01

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

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

    NASA Astrophysics Data System (ADS)

    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 <0.01. The analysis demonstrates both the efficacy of the new 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.

  5. Evaluation of cloud base height measurements from ceilometer CL31 and MODIS satellite over Ahmedabad, India

    NASA Astrophysics Data System (ADS)

    Sharma, S.; Vaishnav, R.; Shukla, M. V.; Kumar, P.; Kumar, P.; Thapliyal, P. K.; Lal, S.; Acharya, Y. B.

    2015-11-01

    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 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.

  6. In-flight intercalibration of FY-3C visible channels with AQUA MODIS

    NASA Astrophysics Data System (ADS)

    Xu, Na; Chen, Lin; Wu, Ronghua; Hu, Xiuqing; Sun, Ling; Zhang, Peng

    2014-11-01

    Intercalibration against a well-calibrated instrument at Low Earth Orbit (LEO) is a common method which has been widely used to assess the in-flight calibration of a new instrument. Different instruments on LEO spacecraft with similar spectral channels can be compared with each other using their simultaneous nadir observations (SNO). The postlaunch calibrations of Medium Resolution Spectral Imager (MERSI) and the Visible Infrared Radiometer (VIRR) in visible channels which are two major multi-spectral imaging radiometers onboard FY-3C are addressed based on SNO intercalibration method. Collection 6 reflectance products of AQUA MODIS are used as reference. The spectral difference impacts of matching channels are simulated and adjusted using GOME-2 hyperspectral measurements. As monitoring the stability of monthly forcing fits, it is found the linear fitting slopes of MERSI VIS channel 1~12 are scene reflectance dependence with relative differences greater than 20%, while the monthly forcing fits of VIRR show well agreement in VIS channels. This is proved to attribute to the nonlinear response of MERSI as the monthly measurements cover different dynamic ranges. A new radiometric calibration equation considering nonlinear correction is proposed based on an on orbit linear adjustment to prelaunch quadratic calibration. The new calibrations are more consistent with SNO samples, and greatly improve the performance over high reflective scene comparing with linear results verified by statistical measurements over Deep Convective Clouds targets. It is demonstrated that other reference is necessary in ocean color channels as MODIS reflectance is within 10% where the nonlinear feature is likely much serious. It is an invaluable lesson that the temporal variation of calibration slope not always indicates the detector's degradation, but maybe is the valuable information that helps to expose undiscovered characters of instrument.

  7. Use of spaceborne lidar for the evaluation of thin cirrus contamination and screening in the Aqua MODIS Collection 5 aerosol products

    NASA Astrophysics Data System (ADS)

    Huang, Jingfeng; Hsu, N. Christina; Tsay, Si-Chee; Liu, Zhaoyan; Jeong, Myeong-Jae; Hansell, Richard A.; Lee, Jaehwa

    2013-06-01

    Cloud contamination from subvisual thin cirrus clouds is still a challenging issue for operational satellite aerosol retrievals. In the A-Train constellation, concurrent high-sensitivity cirrus observations from the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) provide us with an unprecedented opportunity to examine the susceptibility of the Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) aerosol retrievals to thin cirrus contamination and to evaluate the robustness of various cirrus screening techniques. Quantitative evaluations indicate that the current cirrus screening schemes in the MODIS Dark Target and Deep Blue Collection 5 aerosol retrievals can effectively remove most cirrus signals while some residual thin cirrus signals still exist with strong spatial and seasonal variability. Results also show significant linkage between thin cirrus occurrence frequency and the susceptibility of aerosol retrievals to thin cirrus contamination. Using the CALIPSO cirrus observations as a reference, we also examined the effectiveness and robustness of eight MODIS-derived cirrus screening parameters. These parameters include apparent reflectance at 1.38 µm (R1.38), cirrus reflectance at 0.66 µm (CR0.66), CR0.66 cirrus flag (CF), reflectance ratio between 1.38 µm and 0.66 µm (RR1.38/0.66), reflectance ratio between 1.38 µm and 1.24 µm (RR1.38/1.24), brightness temperature difference between 8.6 µm and 11 µm (BTD8.6-11), brightness temperature difference between 11 µm and 12 µm (BTD11-12), and cloud phase infrared approach (CPIR). Among these parameters, RR1.38/0.66 achieves the best overall performance, followed by the BTD11-12. Results from several test cases suggest that the cirrus screening schemes in the operational MODIS aerosol retrieval algorithms can be further improved to reduce thin cirrus contamination.

  8. MODIS Rapid Response: On-the-ground, real time applications of scientific satellite imagery

    NASA Astrophysics Data System (ADS)

    Schmaltz, J. E.; Riebeek, H.; Kendall, J. D.

    2009-12-01

    Since 2001, NASA’s MODIS Rapid Response Project has been providing fire detections and imagery in near real time for a wide variety of application users. The project web site provides MODIS imagery in true color and false color band combinations, a vegetation index, and land surface temperature - in both uncorrected swath format and geographically corrected subset regions within a few hours of data acquisition. The uncorrected swath format data is available worldwide. Geographically corrected subset images cover the world's land areas and adjoining waters, as well as the entire Arctic and Antarctic. Images are available twice daily, in the morning from the Terra satellite and in the afternoon from the Aqua satellite. A wide range of user communities access this information to get a rapid, 250 meter-resolution overview of ground conditions for fire management, crop and famine monitoring and forecasting, disaster response (floods, storms), dust and aerosol monitoring, aviation (tracking volcanic ash), monitoring sea ice conditions, environmental monitoring, and more. The scientific community uses imagery to locate phenomena of interest prior to ordering and processing data and to support the day-to-day planning of field campaigns. Rapid Response imagery is used extensively to support education and public outreach, both by NASA and other organizations, and is frequently found in newspapers, books, TV, and the web. California wildfires, 26 October 2003, Terra MODIS

  9. Relative spectral response corrected calibration inter-comparison of S-NPP VIIRS and Aqua MODIS thermal emissive bands

    NASA Astrophysics Data System (ADS)

    Efremova, Boryana; Wu, Aisheng; Xiong, Xiaoxiong

    2014-09-01

    The S-NPP Visible Infrared Imaging Radiometer Suite (VIIRS) instrument is built with strong heritage from EOS MODIS, and has very similar thermal emissive bands (TEB) calibration algorithm and on-board calibrating source - a V-grooved blackbody. The calibration of the two instruments can be assessed by comparing the brightness temperatures retrieved from VIIRS and Aqua MODIS simultaneous nadir observations (SNO) from their spectrally matched TEB. However, even though the VIIRS and MODIS bands are similar there are still relative spectral response (RSR) differences and thus some differences in the retrieved brightness temperatures are expected. The differences depend on both the type and the temperature of the observed scene, and contribute to the bias and the scatter of the comparison. In this paper we use S-NPP Cross-track Infrared Sounder (CrIS) data taken simultaneously with the VIIRS data to derive a correction for the slightly different spectral coverage of VIIRS and MODIS TEB bands. An attempt to correct for RSR differences is also made using MODTRAN models, computed with physical parameters appropriate for each scene, and compared to the value derived from actual CrIS spectra. After applying the CrIS-based correction for RSR differences we see an excellent agreement between the VIIRS and Aqua MODIS measurements in the studied band pairs M13-B23, M15-B31, and M16- B32. The agreement is better than the VIIRS uncertainty at cold scenes, and improves with increasing scene temperature up to about 290K.

  10. Monitoring ice break-up on the Mackenzie River, Canada, from MODIS Aqua and Terra observations

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    Monitoring the response of river ice phenology to variability and changes in high-latitude climate conditions is critical for improving our understanding of northern hydrology and related impacts on geochemical and biological processes. Shorter ice cover duration, thinner ice, and earlier break-up also influence the winter road season, thereby influencing industrial development and the delivery of goods to northern communities. Increased upstream temperatures over the Mackenzie River Basin have caused shorter ice cover seasons, consequently changing the timing and severity of river ice flow in this high-latitude region. This study involves the analysis of Moderate Resolution Imaging Spectroradiometer (MODIS) Level 3 500-m snow products (Aqua and Terra), complemented with 250-m Level 1b data, to monitor ice cover during the break-up period on the Mackenzie River over the 2001-2013 period. Results from the analysis of 10 ice seasons (2003-2012) show that first day ice-off was observed between day of year (DY) 115-125 and ended between DY 145-155, resulting in average melt durations of about 30-40 days. Additional ice-on and ice-off days observed during 2003-2012 resulted from northern flowing entrained river ice that extended the break-up season until DY 155-163. Floating ice flowing northbound could therefore generate multiple periods of ice-cover and ice-free days at the same geographic location. During the ice break-up seasons from 2003-2012, ice melt was initiated by in situ melt over drainage basin (thermodynamic), especially between 61-62o N. However, ice break-up above the 62o N was more dynamically driven. In addition, ice jams were found to be largely controlled by river morphology.

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

    NASA Technical Reports Server (NTRS)

    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.

  12. Sea ice properties in the Bohai Sea measured by MODIS-Aqua: 2. Study of sea ice seasonal and interannual variability

    NASA Astrophysics Data System (ADS)

    Shi, Wei; Wang, Menghua

    2012-07-01

    During the 2009-2010 winter, the Bohai Sea experienced its most severe sea ice event in four decades, which caused significant economic losses, affected marine transportation and fishery, and impacted the entire marine ecosystem in the region. Measurements from the Moderate Resolution Imaging Spectroradiometer (MODIS) on the Aqua satellite from 2002 to 2010 and surface atmosphere temperature (SAT) data from the National Centers for Environmental Prediction (NCEP) are used to study and quantify the extreme sea ice event in the 2009-2010 winter and the interannual variability of the regional sea ice properties, as well as the relationship between sea ice and the climate variability in the Bohai Sea. The mean sea ice reflectance from MODIS-Aqua visible and near-infrared wavelengths are 9.33%, 13.26%, and 12.60% in the months of December 2009, January 2010, and February 2010, respectively, compared with the monthly average sea ice reflectance values (from 2002 to 2010) of 9.35%, 11.21%, and 11.41% in the same three winter months. The sea ice monthly average coverages are ~ 5427, ~ 27,414, and ~ 21,156 km2 in these three winter months. These values are significantly higher than the averages of monthly sea ice coverage of ~ 2735, ~ 11,119, and ~ 10,287 km2 in the Bohai Sea in December, January, and February between 2002 and 2010. Most of the sea ice coverage was located in the northern Bohai Sea. Both the intra-seasonal and interannual sea ice variability in the Bohai Sea is found to be related closely to SAT. The mechanism of anomalous SAT and intense sea ice severity are also discussed and attributed to large-scale climate changes due to the variability of the Arctic Oscillation (AO) and Siberian High (SH).

  13. Long term (2003-2012) spatio-temporal MODIS (Terra/Aqua level 3) derived climatic variations of aerosol optical depth and cloud properties over a semi arid urban tropical region of Northern India

    NASA Astrophysics Data System (ADS)

    Kumar, Adarsh

    2014-02-01

    Aerosol optical depth (AOD) values at 550 nm derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor onboard NASA's Terra and Aqua satellites, for the 10 years period of 2003-2012 have been analyzed in the present study. The retrieved satellite data (Terra/Aqua) has been used to investigate the temporal heterogeneity in columnar aerosol characteristics over a semi arid urban tropical Delhi zone (28° 34‧, 77° 07‧, 233 m ASL) of Northern India with a resolution of 1° × 1° grid in magnitude. Aerosol optical depths have found to be increased >25% across Delhi region of India during the study period of 2003-2012. Yearly mean Terra/Aqua AOD values have shown an increasing trend at a rate of 0.005/0.009 per year respectively. However, seasonally winter means Terra/Aqua AOD values exhibit an increasing trend at a rate of ˜0.012/0.007 per year respectively. In order to provide a better understanding of aerosol-cloud interaction, a single paired one tailed distribution student's t-Test has been applied to the Terra AOD values and cloud parameters. The results extracted in the present study are compared with the earlier studies as well as with the AOD values over various other Indian regions.

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

    NASA Astrophysics Data System (ADS)

    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 dust from the exposed sea-bed under strong northerly and north-easterly winds, and was found to be slightly larger during summer. From this analysis we have excluded the Aral Sea, over which the AOD values were extreme (up to 2.1 and 1.3 during July and January, respectively). The AOD exhibits statistically-significant increasing trend, with an ~40% mean regional relative change. The changes over are more pronounced over and around the Aral Sea, and are stronger during the warm period of the year (April to September). Our results suggest that these trends are associated with increased dust transport from the exposed Aral Sea sea-bed during the study period, which will be examined with the trends of the frequency and strength of aerosol events over central Asia, as well as their association with the Aral Sea desertification.

  15. Satellite Monitoring of Urban Air Pollution using MODIS and VIIRS

    NASA Astrophysics Data System (ADS)

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

    2013-05-01

    Due to rapid economical growth in many developing countries, the problem of deteriorating air quality is becoming an important societal issue of public health over mega cities around the world. Although there are many networks of surface PM2.5 and PM10 measurements in place to monitor the level of air pollutant over these urban sites, satellite data are still required to provide comprehensive information on the overall big picture regarding the spatial distribution of aerosols and their transport paths into the surrounding regions. In this paper, we will demonstrate the capability of a new satellite algorithm to retrieve aerosol optical thickness and single scattering albedo over bright-reflecting surfaces such as urban areas. Such retrievals have been difficult to perform using previously available algorithms that use wavelengths from the mid-visible to the near IR because they have trouble separating the aerosol signal from the contribution due to the bright surface reflectance. The new algorithm, called Deep Blue, utilizes blue-wavelength measurements from instruments such as MODIS and VIIRS to infer the properties of aerosols, since the surface reflectance over land in the blue part of the spectrum is much lower than for longer wavelength channels. We have validated the satellite retrieved aerosol optical thickness from both MODIS Collection 6 and new VIIRS Deep Blue products with data from AERONET sunphotometers over urban sites. The comparisons show reasonable agreements between these two. These new satellite products will allow scientists to determine quantitatively the aerosol properties near sources using high spatial resolution measurements from MODIS and VIIRS instruments. The multiyear satellite measurements since 2000 from MODIS will be utilized to investigate the interannual variability of source, pathway, and aerosol loading associated with these urban pollutions. The quantitative effects of direct radiative forcing of these air borne aerosol particles on climate system will also be discussed.

  16. On the relative stability of CERES reflected shortwave and MISR and MODIS visible radiance measurements during the Terra satellite mission

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

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

  17. Aerosol-cloud relations over Eastern Mediterranean as seen from MODIS satellite observations

    NASA Astrophysics Data System (ADS)

    Georgoulias, Aristeidis K.; Kourtidis, Konstantinos; Zanis, Prodromos; Alexandri, Georgia; Pöschl, Ulrich

    2014-05-01

    In this work, the aerosol-cloud relations over the region of Eastern Mediterranean are investigated at a spatial resolution of 0.1 degrees (~10km). Within the QUADIEEMS project, a 13-year gridded dataset with several aerosol and cloud related parameters has been compiled using level-2 single pixel measurements from MODIS TERRA and MODIS AQUA satellite sensors. The aerosol gridded dataset has been successfully validated against ground-based measurements from 12 AERONET sites. The high spatial resolution of the dataset allows for the investigation of local phenomena. In addition, the combined use of MODIS data with data from the Earth Probe TOMS and OMI satellite sensors, data from the ERA-interim reanalysis, data from the GOCART chemical-aerosol-transport model and the MACC reanalysis, allows for the quantification of the relative contribution of different aerosol types to the total aerosol optical depth (AOD550). Using these results, we calculate the relations of AOD550 with the cloud effective particle radius, the cloud droplet number concentration, the cloud cover and the cloud water path. Further, we repeat this procedure taking into account each time days characterized by a dominant aerosol type (e.g. anthropogenic, dust) and different types of clouds (e.g. liquid, ice, low, high, etc). We present here selected results from this ongoing research. This work is funded by QUADIEEMS project which is co-financed by the European Social Fund (ESF) and national resources under the operational programme Education and Lifelong Learning (EdLL) within the framework of the Action "Supporting Postdoctoral Researchers".

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

    NASA Astrophysics Data System (ADS)

    Nguyen, Thanh T. N.; Bui, Hung Q.; Pham, Ha V.; Luu, Hung V.; Man, Chuc D.; Pham, Hai N.; Le, Ha T.; Nguyen, Thuy T.

    2015-09-01

    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.

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

    NASA Astrophysics Data System (ADS)

    Gkikas, Antonis; Hatzianastassiou, Nikolaos

    2013-04-01

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

  20. Comparison of aerosol optical depth between CALIOP and MODIS-Aqua for CALIOP aerosol subtypes over the ocean

    NASA Astrophysics Data System (ADS)

    Kim, Man-Hae; Kim, Sang-Woo; Yoon, Soon-Chang; Omar, Ali H.

    2013-12-01

    Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) aerosol optical depth (AOD) has been compared with the Moderate Resolution Imaging Spectroradiometer (MODIS)-Aqua AOD using Level 2 products of both instruments. Such comparisons have been performed for five different aerosol subtypes classified by CALIOP algorithm, namely clean marine, dust, polluted dust, polluted continental, and biomass burning, over the ocean from June 2006 to December 2010. MODIS AOD at 550 nm (0.111 ± 0.079) for the collocated data pairs is about 63% higher than CALIOP AOD at 532 nm (0.068 ± 0.073). For clean marine, MODIS AOD (0.110 ± 0.064) is almost twice the CALIOP AOD (0.056 ± 0.038), and the difference between the AOD values has a strong latitude dependence likely related to the surface wind speed over the ocean. The difference in AOD for dust (13%) is observed to be the lowest among the five aerosol types under consideration, but it shows a slight regional variation. The discrepancy of AOD for dust also shows strong dependency on the layer mean of the particulate depolarization ratio. CALIOP AOD is higher than MODIS AOD for both polluted dust and polluted continental by 15% and 29%, respectively, for most of the ocean. One of the possible reasons for the difference is the misclassification of clean marine (or marine + dust) as polluted dust and polluted continental in the CALIOP algorithm. For biomass burning, uncertainty in the layer base altitude is thought to be one of the main reasons for the lower value of CALIOP AOD.

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

    NASA Technical Reports Server (NTRS)

    Hutchison, Keith D.

    2007-01-01

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

  2. Understanding Differences Between Co-Incident CloudSat, Aqua/MODIS and NOAA18 MHS Ice water Path Retrievals Over the Tropical Oceans

    NASA Technical Reports Server (NTRS)

    Pittman, Jasna; Robertson, Franklin; Blankenship, Clay

    2008-01-01

    Accurate measurement of the physical and radiative properties of clouds and their representation in climate models continues to be a challe nge. Model parameterizations are still subject to a large number of t unable parameters; furthermore, accurate and representative in situ o bservations are very sparse, and satellite observations historically have significant quantitative uncertainties, particularly with respect to particle size distribution (PSD) and cloud phase. Ice Water Path (IWP), or amount of ice present in a cloud column, is an important cl oud property to accurately quantify, because it is an integral measur e of the microphysical properties of clouds and the cloud feedback pr ocesses in the climate system. This paper investigates near co-incident retrievals of IWP over tropical oceans using three diverse measurem ent systems: radar from CloudSat, Vis/IR from Aqua/MODIS, and microwa ve from NOAA-18IMHS. CloudSat 94 GHz radar measurements provide high resolution vertical and along-orbit structure of cloud reflectivity a nd enable IWP (and IWC) retrievals. Overlapping MODIS measurements of cloud optical thickness and phase allow estimates of IWP when cloud tops are identified as being ice. Periodically, NOAA18 becomes co-inci dent in space I time to enable comparison of A-Train measurements to IWP inferred from the 157 and 89 GHz channel radiances. This latter m easurement is effective only for thick convective anvil systems. We s tratify these co-incident data (less than 4 minutes separation) into cirrus only, cirrus overlying liquid water clouds, and precipitating d eep convective clouds. Substantial biases in IWP and ice effective ra dius are found. Systematic differences in these retrievals are consid ered in light of the uncertainties in a priori assumptions ofPSDs, sp ectral sensitivity and algorithm strategies, which have a direct impact on the IWP product.

  3. Sea surface temperature and ocean colour (MODIS/AQUA) space and time variability in Indonesian Sea coral reef systems from 2002 to 2011

    NASA Astrophysics Data System (ADS)

    Polónia, A. R.; Figueiredo, M.; Cleary, D. F. R.; de Voogd, N. J.; Martins, A.

    2011-11-01

    Presently, there are already Indonesian coral reefs experiencing massive destruction caused by anthropogenic localscale sources (sedimentation, eutrophication) and/or natural climatic global-scale sources (temperature) which can inflict acute and/or chronic impacts on these ecosystems. This study was carried out with the aim of identifying possible sources of impact in coral reef systems associated with two of the most populated Indonesian cities (Makassar and Jakarta). MODIS/AQUA satellite-derived Ocean Colour (Chl a in mg m-3) and Sea Surface Temperature (SST in °C) data were used for the 2002-2011 period. These were related with large-scale atmospheric climatic indices, namely the Southern Oscillation Index (SOI), the Dipole Mode Index (DMI), and the North Atlantic Oscillation Index (NAOI). Beyond the expected influence of the El Niño Index over the Indonesian region, we present first evidence of the significant influence of the NAOI in Indonesian ecosystems. The results show strong seasonal correlation between the NAOI and two key parameters for the coral reef health: chlorophyll a (at Jakarta) and SST (at Makassar). During the dry season, and especially over the Spermonde coral reef system, a seasonal SST uptrend was observed culminating in the first bleaching event registered in this area during the hottest year (2010) since 2002.

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

    NASA Astrophysics Data System (ADS)

    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 conducted with Mesoscale Model 5 (MM5) numerical weather prediction data for 2011. Preliminary results of ANN streamflow estimation are promising for short-term operational use in snow-dominated basins. Keywords: Artificial Neural Network; Snow; MODIS; Streamflow Estimation; Turkey

  5. Monitoring bio-optical processes using NPP-VIIRS and MODIS-Aqua ocean color products

    NASA Astrophysics Data System (ADS)

    Arnone, Robert; Ladner, Sherwin; Fargion, Giulietta; Martinolich, Paul; Vandermeulen, Ryan; Bowers, Jennifer; Lawson, Adam

    2013-06-01

    Same day ocean color products from the S-NPP and MODIS provide for a new capability to monitor changes in the bio-optical processes occurring in coastal waters. The combined use of multiple looks per day from several sensors can be used to follow the water mass changes of bio-optical properties. Observing the dynamic changes in coastal waters in response to tides, re-suspension and river plume dispersion, requires sequential ocean products per day to resolve bio-optical processes. We examine how these changes in bio-optical properties can be monitored using the NPP and MODIS ocean color products. Additionally, when linked to ocean circulation, we examine the changes resulting from current advection compared to bio-optical processes. The inter-comparison of NPP and MODIS ocean products are in agreement so that diurnal changes surface bio-optical processes can be characterized.

  6. Lidar Ratios for Dust Aerosols Derived From Retrievals of CALIPSO Visible Extinction Profiles Constrained by Optical Depths from MODIS-Aqua and CALIPSO/CloudSat Ocean Surface Reflectance Measurements

    NASA Technical Reports Server (NTRS)

    Young, Stuart A.; Josset, Damien B.; Vaughan, Mark A.

    2010-01-01

    CALIPSO's (Cloud Aerosol Lidar Infrared Pathfinder Satellite Observations) analysis algorithms generally require the use of tabulated values of the lidar ratio in order to retrieve aerosol extinction and optical depth from measured profiles of attenuated backscatter. However, for any given time or location, the lidar ratio for a given aerosol type can differ from the tabulated value. To gain some insight as to the extent of the variability, we here calculate the lidar ratio for dust aerosols using aerosol optical depth constraints from two sources. Daytime measurements are constrained using Level 2, Collection 5, 550-nm aerosol optical depth measurements made over the ocean by the MODIS (Moderate Resolution Imaging Spectroradiometer) on board the Aqua satellite, which flies in formation with CALIPSO. We also retrieve lidar ratios from night-time profiles constrained by aerosol column optical depths obtained by analysis of CALIPSO and CloudSat backscatter signals from the ocean surface.

  7. Assessment of MODIS-Aqua chlorophyll-a algorithms in coastal and shelf waters of the eastern Arabian Sea

    NASA Astrophysics Data System (ADS)

    Tilstone, Gavin H.; Lotliker, Aneesh A.; Miller, Peter I.; Ashraf, P. Muhamed; Kumar, T. Srinivasa; Suresh, T.; Ragavan, B. R.; Menon, Harilal B.

    2013-08-01

    The use of ocean colour remote sensing to facilitate the monitoring of phytoplankton biomass in coastal waters is hampered by the high variability in absorption and scattering from substances other than phytoplankton. The eastern Arabian Sea coastal shelf is influenced by river run-off, winter convection and monsoon upwelling. Bio-optical parameters were measured along this coast from March 2009 to June 2011, to characterise the optical water type and validate three Chlorophyll-a (Chla) algorithms applied to Moderate Resolution Imaging Spectroradiometer on Aqua (MODIS-Aqua) data against in situ measurements. Ocean Colour 3 band ratio (OC3M), Garver-Siegel-Maritorena Model (GSM) and Generalized Inherent Optical Property (GIOP) Chla algorithms were evaluated. OC3M performed better than GSM and GIOP in all regions and overall, was within 11% of in situ Chla. GSM was within 24% of in situ Chla and GIOP on average was 55% lower. OC3M was less affected by errors in remote sensing reflectance Rrs(λ) and by spectral variations in absorption coefficient (aCDOM(λ)) of coloured dissolved organic material (CDOM) and total suspended matter (TSM) compared to the other algorithms. A nine year Chla time series from 2002 to 2011 was generated to assess regional differences between OC3M and GSM. This showed that in the north eastern shelf, maximum Chla occurred during the winter monsoon from December to February, where GSM consistently gave higher Chla compared to OC3M. In the south eastern shelf, maximum Chla occurred in June to July during the summer monsoon upwelling, and OC3M yielded higher Chla compared to GSM. OC3M currently provides the most accurate Chla estimates for the eastern Arabian Sea coastal waters.

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

    NASA Technical Reports Server (NTRS)

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

    NASA Astrophysics Data System (ADS)

    Phonekeo, V.; Samarakoon, L.; Saphangthong, T.

    2014-02-01

    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.

  10. New methods for studying the spatiotemporal variation of snow cover based on combination products of MODIS Terra and Aqua

    NASA Astrophysics Data System (ADS)

    Wang, Xianwei; Xie, Hongjie

    2009-06-01

    SummaryBased on multi-day combination of Terra and Aqua MODIS snow cover products (cloud cover less than 10%), this study developed new snow cover index (SCI), snow-covered duration/days (SCD) map, snow cover onset dates (SCOD) map and snow cover melting dates (SCMD) map, one each per hydrological year, to further examine the spatiotemporal variations of snow cover. Daily in situ snow depth observations in northern Xinjiang, China from 2001 to 2005 were used to validate the new maps. Our results indicate that the SCD maps had an overall agreement of 90% with in situ observations of snow cover days at 20 stations in the study area, and the SCOD and SCMD maps also had good agreements with the in situ measurements, with a mean value of 1 week forward shift and 1 week backward shift, respectively, due to transient snowfall events in early fall and in late spring. The snow cover index (SCI) (km 2 day), first proposed here, contains both snow cover duration and extent for 1 hydrological year and indicates that the 2001-2002 hydrologic year had the most snow cover while the 2005-2006 had the least. While the SCD map provides the snow cover duration/days of each pixel in a hydrologic year, the SCOD and SCMD maps give specific dates when the snow cover begins and when it melts away at the pixel. Together, SCD, SCI, SCOD and SCMD can provide crucial information on spatiotemporal variation of snow cover conditions for any region of interest. This could potentially be critical information for local water agencies for planning water use and for mitigating snow-caused disaster. Long term availability of MODIS type of snow cover data for producing such datasets is key to study the connection between snow cover change and global climate change.

  11. Predicting the Invasion Potential of a Puerto Rican Frog in Hawaii using MODIS Satellite Imagery

    NASA Astrophysics Data System (ADS)

    Bisrat, S. A.; White, M. A.

    2008-12-01

    The Puerto Rican coqui frog (Eleutherodactylus coqui, hereafter coqui), which was introduced into Hawaii accidentally via commercial nurseries, is an aggressive invasive species in Hawaii. The coqui threatens Hawaii's unique ecological communities because it predates upon endemic invertebrates, which comprise the large majority of Hawaii's endemic fauna. Coqui frogs also affect real estate valuations because of their loud mating calls. Despite this widespread problem, the potential coqui range in Hawaii is currently unknown, making control and management efforts difficult. We fitted linear discriminant analysis (LDA), logistic regression (LR) via generalized linear models (GLMs), generalized additive models (GAMs), classification trees (CTs), random forests (RF), and support vector machine (SVM) to model the species distribution and map their invasion potential. We used five MODIS satellite imagery-derived biophysical variables as explanatory variables: leaf area index (LAI), fraction of photosynthetically active radiation absorbed by vegetation (FPAR), enhanced vegetation index (EVI), normalized difference vegetation index (NDVI), and land surface temperature (LST) from three MODIS products: MOD11 (LST), MOD13 (LAI and FPAR), and MOD15 (Vegetation Index) (collection 4). We used 2000-2005 MODIS data from Aqua and Terra satellites to generate monthly climatologies for each biophysical variable. We collected presence/absence data from Puerto Rico and Hawaii using a 1 km grid overlaid over the entire islands of Puerto Rico and the Island of Hawaii by sampling every other pixel of the grid intersecting with the road network. We then used the dataset from Puerto Rico to train the six models while the Hawaii dataset was used as a test set. All six models predicted the invasion potential of coqui frogs in Hawaii with a moderate success with mean Kappa value of 0.31, mean area under the curve of receiver operating characteristics (AUC) of 0.75 and mean classification accuracy (CA) of 0.69. RF and SVM outperformed the other classifiers with Kappa value of 0.4, AUC value of 0.79 and CA of 0.71 for RF and Kappa value of 0.4, AUC value of 0.71 and CA value of 0.72 for SVM. These results suggest climate matching between the native and the introduced habitats of coqui frogs is not strong. Further, the results suggest coqui frogs in their introduced habitat are not showing strong niche conservation.

  12. Comparison of unfiltered CERES radiances measured from the S-NPP and Aqua satellites over matched sites

    NASA Astrophysics Data System (ADS)

    Szewczyk, Z. P.; Smith, G. L.; Priestley, Kory J.

    2015-10-01

    The focus of this paper is to introduce a novel strategy for comparison of unfiltered radiances in remote sensing devised for CERES scanners. The strategy is referred to as "matched sites targeting", in which CERES instruments scan at nadir along their respective collocated ground-tracks. This strategy is enabled by similarities in the Suomi-NPP (FM5) and Aqua (FM3) satellite orbits, and a special scan profile available for the CERES scanners. Comparison of collected data in this strategy is done at a footprint level for a more stringent test of the consistency between the two instruments (FM5 and FM3) for specific scene types, as averages of 330 collocated nadir samples are compared. A comparison of comprehensive "all-sky" measurements is also included as a reference. Results of the unfiltered radiance comparison are based on ES8 or ERBE-like data product using Edition-1 for FM5, and Edition-4 for FM3; cloud coverage is verified using MODIS data available in a SSF product.

  13. Comparison Between NPP-VIIRS Aerosol Data Products and the MODIS AQUA Deep Blue Collection 6 Dataset Over Land

    NASA Technical Reports Server (NTRS)

    Sayer, Andrew M.; Hsu, N. C.; Bettenhausen, C.; Lee, J.; Kondragunta, S.

    2013-01-01

    Aerosols are small particles suspended in the atmosphere and have a variety of natural and man-made sources. Knowledge of aerosol optical depth (AOD), which is a measure of the amount of aerosol in the atmosphere, and its change over time, is important for multiple reasons. These include climate change, air quality (pollution) monitoring, monitoring hazards such as dust storms and volcanic ash, monitoring smoke from biomass burning, determining potential energy yields from solar plants, determining visibility at sea, estimating fertilization of oceans and rainforests by transported mineral dust, understanding changes in weather brought upon by the interaction of aerosols and clouds, and more. The Suomi-NPP satellite was launched late in 2011. The Visible Infrared Imaging Radiometer Suite (VIIRS) aboard Suomi-NPP is being used, among other things, to determine AOD. This study compares the VIIRS dataset to ground-based measurements of AOD, along with a state-of-the-art satellite AOD dataset (the new version of the Moderate Resolution Imaging Spectrometer Deep Blue algorithm) to assess its reliability. The Suomi-NPP satellite was launched late in 2011, carrying several instruments designed to continue the biogeophysical data records of current and previous satellite sensors. The Visible Infrared Imaging Radiometer Suite (VIIRS) aboard Suomi-NPP is being used, among other things, to determine aerosol optical depth (AOD), and related activities since launch have been focused towards validating and understanding this new dataset through comparisons with other satellite and ground-based products. The operational VIIRS AOD product is compared over land with AOD derived from Moderate Resolution Imaging Spectrometer (MODIS) observations using the Deep Blue (DB) algorithm from the forthcoming Collection 6 of MODIS data

  14. Dynamic Regionalization of the Gulf of Mexico based on normalized radiances (nLw) derived from MODIS-Aqua

    NASA Astrophysics Data System (ADS)

    Callejas-Jimenez, Mariana; Santamaria-del-Angel, Eduardo; Gonzalez-Silvera, Adriana; Millan-Nuñez, Roberto; Cajal-Medrano, Ramon

    2012-04-01

    A dynamic regionalization of the Gulf of Mexico (GoM) was carried out based on normalized radiances derived from MODIS-Aqua while considering its seasonal variability (Hurricane and Non-hurricane seasons). Daily images with a 1 km resolution from June 2002 to May 2007 were used. To define the dynamic regions, the first Standard Empirical Orthogonal Function (SEOF1) was calculated by combining nLw412 nm and nLw488 nm. The GoM was divided into two large provinces: oceanic and coastal. Within the oceanic province there are three regions with oligotrophic conditions. The coastal province displayed two sub-provinces (the northern and southern Gulf of Mexico) within which eight regions were located. Two of them were classified as transition regions. In general, most regions could be associated with general circulation patterns and/or river discharge influence. When looking at changes in coverage and the number of divisions, this regionalization shows a bi-seasonal modulation governed by hurricane seasons. The approximation presented here allows the dynamic regionalization of the GoM, a zone characterized by small surface gradients on Chl a and SST, including the recognition of smaller structures such as eddies.

  15. Vegetation cover quality assessment through MODIS time series satellite data in an urban region

    NASA Astrophysics Data System (ADS)

    Zoran, M. A.; Savastru, R. S.; Savastru, D. M.; Pavelescu, G. M.; Tautan, M. N.; Miclos, S. I.; Baschir, L. A.

    2013-08-01

    To preserve urban vegetation land cover quality and mitigate its degradation is an important task for urban planning and environmental management of Bucharest metropolitan area in Romania. Since vegetation land cover dynamics directly affect the urban landscape characteristics and air quality, remote sensing represents an effective tool for vegetation land cover quality assessment at regional scale. In particular, the use of satellite-based vegetation indices, like the NDVI (Normalized Difference Vegetation Index), can provide important information when evaluating Urban Vegetation Cover Quality (UVCQ) patterns in urban areas, which represents one of the most sensitive landscape components to urban environmental degradation. This paper proposes an approach for the regional-scale assessment of UVCQ by means of an NDVI-based (functional) indicator using freely available time series MODIS Terra/Aqua (Moderate Resolution Imaging Spectroradiometer) satellite data. As a case study, Bucharest metropolitan area landscape experiencing climate and anthropogenic changes, increasing human pressure and high vulnerability to degradation was chosen. As UVCQ indicator, the NDVI-based vegetation cover classification was produced by means of unsupervised multivariate statistical techniques and compared with spatio-temporal changes during 2002-2012 period, statistical indicators, and field data related to land cover management observed in the study area. Results demonstrate that the obtained remotely sensed vegetation land cover characterization can be effectively considered as a proxy of the UVCQ status of the examined area. Due to the large availability over time and low cost of satellite images, the proposed approach can be applied to wider urban/periurban regions, to monitor vegetation quality and indirectly control vegetation land degradation.

  16. Impact of climate and anthropogenic changes on urban surface albedo assessed from time-series MODIS satellite data

    NASA Astrophysics Data System (ADS)

    Zoran, Maria A.; Dida, Adrian I.; Zoran, Liviu Florin V.

    2015-10-01

    Urbanization may be considered the most significant anthropogenic force that has brought about fundamental changes in urban land cover and landscape pattern around the globe, being one of the crucial issues of global change in the 21st century affecting urban ecosystem. In the physical climate system, land surface albedo determines the radiation balance of the surface and affects the surface temperature and boundary-layer structure of the atmosphere. Due to anthropogenic and natural factors, urban land covers changes result is the land surfaces albedo changes. The main aim of this paper is to investigate the albedo patterns dynamics due to the impact of atmospheric pollution and climate variations on land cover of Bucharest metropolitan area, Romania based on satellite remote sensing MODIS Terra/Aqua (Moderate Imaging Spectroradiometer) data over 2000-2014 time period. This study is based on MODIS derived biogeophysical parameters land surface BRDF/albedo products and in-situ monitoring ground data (as air temperature, aerosols distribution, relative humidity, etc.). For urban land cover changes over the same investigated period have been used also IKONOS satellite data. Due to deforestation in the periurban areas albedo changes appear to be the most significant biogeophysical effect in temperate forests. As the physical climate system is very sensitive to surface albedo, urban/periurban vegetation systems could significantly feedback to the projected climate change modeling scenarios through albedo changes.

  17. Space environment's effect on MODIS calibration

    NASA Astrophysics Data System (ADS)

    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.

  18. MODIS Collection 6 aerosol products: Comparison between Aqua's e-Deep Blue, Dark Target, and "merged" data sets, and usage recommendations

    NASA Astrophysics Data System (ADS)

    Sayer, A. M.; Munchak, L. A.; Hsu, N. C.; Levy, R. C.; Bettenhausen, C.; Jeong, M.-J.

    2014-12-01

    The Moderate Resolution Imaging Spectroradiometer (MODIS) Atmospheres data product suite includes three algorithms applied to retrieve midvisible aerosol optical depth (AOD): the Enhanced Deep Blue (DB) and Dark Target (DT) algorithms over land, and a DT over-water algorithm. All three have been refined in the recent "Collection 6" (C6) MODIS reprocessing. In particular, DB has been expanded to cover vegetated land surfaces as well as brighter desert/urban areas. Additionally, a new "merged" data set which draws from all three algorithms is included in the C6 products. This study is intended to act as a point of reference for new and experienced MODIS data users with which to understand the global and regional characteristics of the C6 DB, DT, and merged data sets, based on MODIS Aqua data. This includes validation against Aerosol Robotic Network (AERONET) observations at 111 sites, focused toward regional and categorical (surface/aerosol type) analysis. Neither algorithm consistently outperforms the other, although in many cases the retrieved AOD and the level of its agreement with AERONET are very similar. In many regions the DB, DT, and merged data sets are all suitable for quantitative applications, bearing in mind that they cannot be considered independent, while in other cases one algorithm does consistently outperform the other. Usage recommendations and caveats are thus somewhat complicated and regionally dependent.

  19. Assessment of suspended particulate matter concentration retrieved by Aqua-MODIS and SeaWiFS in the East China Sea

    NASA Astrophysics Data System (ADS)

    Cui, Qianfang; Pan, Delu; Bai, Yan; He, Xianqiang; Chen, Jianyu

    2012-09-01

    The East China Sea (ECS) is the 11th largest marginal seas around the world. ECS has widely continental shelf, and has relatively high concentration of suspended particulate matter (TSM) affected by the terrestrial material from the large rivers, including the Changjiang River, and also affected by the resuspension in the winter. Recently, several regional algorithms for the TSM retrieval in the ECS have been proposed, such as the algorithms developed by Zhang et al. (2010) and Han et al. (2006). Due to the variation of the optical properties of TSM, it is significant to study whether existing algorithms are adequate and reliable for the inversion of the concentration of TSM in the ECS for all seasons. Yet, up to now, the validation of the satellite retrieved TSM is still lack due to the insufficient of the in-situ data and the standard TSM product in the ECS. In the past three years, we have carried out four seasonal cruises covering the whole ECS, including the spring cruise from May to June 2011, the summer cruise in August 2009, the autumn cruise from November to December 2010, and the winter cruise from December 2009 to January 2010. In this paper, we firstly analyzed the spatial-temporal distribution of the TSM in the ECS. The results showed that there was remarkable seasonal variation with higher concentration in the winter half year and lower concentration in the summer half year. The concentration of TSM was higher inshore than that of offshore. The isolines were parallel to the shoreline as a whole. There was a turbid water tongue with notably seasonal variation spreading to southeast at the 29°N in the middle of the ECS. Finally, based on the remote sensing reflectance retrieved by the Aqua-MODIS and SeaWiFS data, the performance of the four inversion algorithms of TSM were evaluated using the in-situ measured TSM data in the ECS, including the Clark's model in the SeaDAS, Zhang's model, Han's model and Tassan's model. The results show that all of the TSM retrieved by the four models have large error as compared with the in-situ data, indicating the strong requirement of the improving the TSM retrieval in the ECS.

  20. Satellites View Growing Gulf Oil Spill (Update) - Duration: 2 minutes, 37 seconds.

    NASA Video Gallery

    On April 30, 2010, the Deepwater Horizon oil rig exploded in the Gulf of Mexico, triggering the largest oil spill in U.S. history. The MODIS instrument, on board NASA's Terra and Aqua satellites, c...

  1. Evaluation of Aerosol Pollution Determination From MODIS Satellite Retrievals for Semi-Arid Reno, NV, USA with In-Situ Measurements

    NASA Astrophysics Data System (ADS)

    Loria-Salazar, S. Marcela

    The aim of the present work is to carry out a detailed analysis of ground and columnar aerosol properties obtained by in-situ Photoacoustic and Integrated Nephelometer (PIN), Cimel CE-318 sunphotometer and MODIS instrument onboard Aqua and Terra satellites, for semi-arid Reno, Nevada, USA in the local summer months of 2012. Satellite determination of local aerosol pollution is desirable because of the potential for broad spatial and temporal coverage. However, retrieval of quantitative measures of air pollution such as Aerosol Optical Depth (AOD) from satellite measurements is challenging because of the underlying surface albedo being heterogeneous in space and time. Therefore, comparisons of satellite retrievals with measurements from ground-based sun photometers are crucial for validation, testing, and further development of instruments and retrieval algorithms. Ground-based sunphotometry and in-situ ground observations show that seasonal weather changes and fire plumes have great influence on the atmosphere aerosol optics. The Apparent Optical Height (AOH) follows the shape of the development of the Convective Boundary Layer (CBL) when fire conditions were not present. However, significant fine particle optical depth was inferred beyond the CBL thereby complicating the use of remote sensing measurements for near-ground aerosol pollution measurements. A meteorological analysis was performed to help diagnose the nature of the aerosols above Reno. The calculation of a Zephyr index and back trajectory analysis demonstrated that a local circulation often induces aerosol transport from Northern CA over the Sierra Nevada Mountains that doubles the Aerosol Optical Depth (AOD) at 500 nm. Sunphotometer measurements were used as a `ground truth' for satellite retrievals to evaluate the current state of the science retrievals in this challenging location. Satellite retrieved for AOD showed the presence of wild fires in Northern CA during August. AOD retrieved using the "dark-target algorithm" may be unrealistically high over the Great Basin. Low correlation was found between AERONET AOD and dark-target algorithm AOD retrievals from Aqua and Terra during June and July. During fire conditions the dark-target algorithm AOD values correlated better with AERONET measurements in August. Use of the Deep-blue algorithm for MODIS data to retrieve AOD did not provide enough points to compare with AERONET in June and July. In August, AOD from deep-blue and AERONET retrievals exhibited low correlation. AEE from MODIS products and AERONET exhibited low correlation during every month. Apparently satellite AOD retrievals need much improvement for areas like semi-arid Reno.

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

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

    The impact of natural and anthropogenic sources of aerosols has gained increasing attention from scientific communities in recent years. Indeed, tropospheric aerosols not only perturb radiative energy balance by interacting with solar and terrestrial radiation, but also by changing cloud properties and lifetime. Furthermore, these anthropogenic and natural air particles, once generated over the source regions, can be transported out of the boundary layer into the free troposphere and can travel thousands of kilometers across oceans and continents resulting in important biogeochemical impacts on the ecosystem. With the launch of SeaWiFS in 1997, Terra/MODIS in 1999, and Aqua/MODIS in 2002, high quality comprehensive aerosol climatology is becoming feasible for the first time. As a result of these unprecedented data records, studies of the radiative and biogeochemical effects due to tropospheric aerosols are now possible. In this talk, we will demonstrate how this newly available SeaWiFS/MODIS aerosol climatology can provide an important piece of puzzles in reducing the uncertainty of estimated climatic forcing due to aerosols. We will start with the global distribution of aerosol loading and their variabilities over both land and ocean on short- and long-term temporal scales observed over the last decade. The recent progress made in Deep Blue aerosol algorithm on improving accuracy of these Sea WiFS / MODIS aerosol products in particular over land will be discussed. The impacts on quantifying physical and optical processes of aerosols over source regions of adding the Deep Blue products of aerosol properties over bright-reflecting surfaces into Sea WiFS / MODIS as well as VIIRS data suite will also be addressed. We will also show the intercomparison results of SeaWiFS/MODIS retrieved aerosol optical thickness with data from ground based AERONET sunphotometers over land and ocean as well as with other satellite measurements. The trends observed in global aerosol loadings of both natural and anthropogenic sources based upon more than a decade of combined MODIS/SeaWiFS data (1997-2011) will be discussed. We will also address the importance of various key issues such as differences in spatial-temporal sampling rates and observation time between different satellite measurements could potentially impact these intercomparisons results, especially for using the monthly mean data, and thus on estimates of long-term aerosol trends.

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

    NASA Astrophysics Data System (ADS)

    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.

  4. Cross-Calibration of Earth Observing System Terra Satellite Sensors MODIS and ASTER

    NASA Technical Reports Server (NTRS)

    McCorkel, J.

    2014-01-01

    The Advanced Spaceborne Thermal Emissive and Reflection Radiometer (ASTER) and Moderate Resolution Imaging Spectrometer (MODIS) are two of the five sensors onboard the Earth Observing System's Terra satellite. These sensors share many similar spectral channels while having much different spatial and operational parameters. ASTER is a tasked sensor and sometimes referred to a zoom camera of the MODIS that collects a full-earth image every one to two days. It is important that these sensors have a consistent characterization and calibration for continued development and use of their data products. This work uses a variety of test sites to retrieve and validate intercalibration results. The refined calibration of Collection 6 of the Terra MODIS data set is leveraged to provide the up-to-date reference for trending and validation of ASTER. Special attention is given to spatially matching radiance measurements using prelaunch spatial response characterization of MODIS. Despite differences in spectral band properties and spatial scales, ASTER-MODIS is an ideal case for intercomparison since the sensors have nearly identical views and acquisitions times and therefore can be used as a baseline of intercalibration performance of other satellite sensor pairs.

  5. Ocean Primary Production Estimates from Terra MODIS and Their Dependency on Satellite Chlorophyll Alpha Algorithms

    NASA Technical Reports Server (NTRS)

    Essias, Wayne E.; Abbott, Mark; Carder, Kendall; Campbell, Janet; Clark, Dennis; Evans, Robert; Brown, Otis; Kearns, Ed; Kilpatrick, Kay; Balch, W.

    2003-01-01

    Simplistic models relating global satellite ocean color, temperature, and light to ocean net primary production (ONPP) are sensitive to the accuracy and limitations of the satellite estimate of chlorophyll and other input fields, as well as the primary productivity model. The standard MODIS ONPP product uses the new semi-analytic chlorophyll algorithm as its input for two ONPP indexes. The three primary MODIS chlorophyll Q estimates from MODIS, as well as the SeaWiFS 4 chlorophyll product, were used to assess global and regional performance in estimating ONPP for the full mission, but concentrating on 2001. The two standard ONPP algorithms were examined with 8-day and 39 kilometer resolution to quantify chlorophyll algorithm dependency of ONPP. Ancillary data (MLD from FNMOC, MODIS SSTD1, and PAR from the GSFC DAO) were identical. The standard MODIS ONPP estimates for annual production in 2001 was 59 and 58 GT C for the two ONPP algorithms. Differences in ONPP using alternate chlorophylls were on the order of 10% for global annual ONPP, but ranged to 100% regionally. On all scales the differences in ONPP were smaller between MODIS and SeaWiFS than between ONPP models, or among chlorophyll algorithms within MODIS. Largest regional ONPP differences were found in the Southern Ocean (SO). In the SO, application of the semi-analytic chlorophyll resulted in not only a magnitude difference in ONPP (2x), but also a temporal shift in the time of maximum production compared to empirical algorithms when summed over standard oceanic areas. The resulting increase in global ONPP (6-7 GT) is supported by better performance of the semi-analytic chlorophyll in the SO and other high chlorophyll regions. The differences are significant in terms of understanding regional differences and dynamics of ocean carbon transformations.

  6. Detection of Harmful Algal Blooms in the Optically Complex Coastal Waters of the Kuwait Bay using Aqua-MODIS data

    NASA Astrophysics Data System (ADS)

    Manche, C. J.; Sultan, M.; Uddin, S.; Al-Dousari, A.; Chouinard, K.

    2013-12-01

    In the optically complex coastal marine waters of the Kuwait Bay, the propagation of Harmful Algal Blooms (HABs) has become a severe issue over the last decade affecting aquaculture a primary component of the Kuwaiti economy. Although several remote sensing based methods of algal bloom detection exist today, few may accurately detect the concentration and identify the type of HABs in Case II waters. The purpose of this study is: (1) assessment of the method that best detects and identifies algal blooms in general and HABs in particular, in the Kuwait Bay, and (2) identification of the factors controlling the occurrence of HABs. Fluorescence Line Height (FLH), Empirical, Bio-Optical, and Operational Methods as well as Ocean Colour 3 Band Ratio (OC3M), Garver-Siegel-Maritorena Model (GSM), and General Inherent Optical Property (GIOP) Chlorophyll-a (Chl-a) algorithms were applied to Moderate Resolution Imaging Spectroradiometer (MODIS) images acquired (07/2002 to 07/2012) over the Kuwait Bay and areas as far east as Shatt Al-Arab and as far south as N. 29.284 (Lat.), E. 50.047 (Long.) decimal degrees. In-situ data (bloom days: 50; sampling locations: 64) collected (09/1999 to 07/2011) from the Kuwait Bay was provided by the Kuwait Institute for Scientific Research and was used to test the reliability of the satellite-based inferences. Tasks accomplished and findings reached include: (1) comparison of in situ to estimated OC3M, GSM, and GIOP chlorophyll concentrations over the sampling locations for the time period 2002 to 2009 showed that OC3M outperformed the two other techniques in predicting the observed distribution and in replicating the measured concentration of the in-situ Chl-a data; (2) applying the OC3M algorithm to a total of 4039 scenes and using threshold values of 3, 4, and 5 mg/m3 Chl-a concentrations we inferred 371, 202, and 124 occurrences in the Kuwait Bay that met their respective threshold; (3) applying the operational method we successfully identified 13 of the reported blooms in Kuwait Bay on cloud free days; the majority of the unidentified events were on cloudy days. This was accomplished by generating difference images between the current satellite OC3M Chl-a concentration image and a background (mean of previous 60 days + 1 mg/m3) using a 14-day window between the analyzed image and those used in the generation of the mean. Predicted blooms in the Kuwait Bay in years 2002 through 2012 are 30, 84, 101, 96, 100, 97, 66, 60, 91, 81 and 29 blooms, respectively. These estimates exceed the observed occurrences and may be attributed to sampling bias (most blooms found >2 km from the shoreline) or due to uncertainties introduced by applying the OC3M algorithms to shallow water (mean depth Kuwait Bay: 22 m) cases; and (4) the temporal correlation of the distribution of the algal blooms in Kuwait Bay with those at the mouth of Shatt Al-Arab suggests a causal effect. Further efforts to more accurately identify HABS and to reduce uncertainties in Chl-a concentration are currently underway.

  7. Mapping Historic Gypsy Moth Defoliation with MODIS Satellite Data: Implications for Forest Threat Early Warning System

    NASA Technical Reports Server (NTRS)

    Spurce, Joseph P.; Hargrove, William; Ryan, Robert E.; Smooth, James C.; Prados, Don; McKellip, Rodney; Sader, Steven A.; Gasser, Jerry; May, George

    2008-01-01

    This viewgraph presentation reviews a project, the goal of which is to study the potential of MODIS data for monitoring historic gypsy moth defoliation. A NASA/USDA Forest Service (USFS) partnership was formed to perform the study. NASA is helping USFS to implement satellite data products into its emerging Forest Threat Early Warning System. The latter system is being developed by the USFS Eastern and Western Forest Threat Assessment Centers. The USFS Forest Threat Centers want to use MODIS time series data for regional monitoring of forest damage (e.g., defoliation) preferably in near real time. The study's methodology is described, and the results of the study are shown.

  8. Investigating the effects of ocean bubbles on enhanced aqua-MODIS aerosol optical depth retrievals in the mid-to-high latitude southern oceans

    NASA Astrophysics Data System (ADS)

    Christensen, Matt

    While satellite remote sensing aerosol measurements are widely used for climate, visibility and air quality studies, issues exist in the current satellite aerosol products such as the Elevated Southern Oceans Anomaly (ESOA) phenomenon. The ESOA is an elevated aerosol optical depth (AOD) belt over high latitude southern oceans detected by passive satellites such as the Moderate Resolution Imaging Spectroradiometer (MODIS) and Multi-angle Imaging SpectroRadiometer (MISR). The ESOA feature, however, is not present in the ground based studies. Cloud contamination was found to have a significant impact on this anomaly, but it is not the only contributor. Wind generated ocean bubbles could increase ocean surface reflectance. However, oceanic bubbles have not been considered in the conventional satellite aerosol studies. In this study, the effects of oceanic bubbles on satellite retrieved AOD values are studied using the linked 6S atmospheric and HydroLight oceanic radiative transfer models. The modeled Top-of atmosphere radiance values are evaluated using collocated observed MAN and MODIS retrievals. This study suggests that oceanic bubbles have an insignificant impact on AOD retrievals for regions with near surface wind speed less than 10 ms-1. However, under high wind scenario, the impact of bubbles to aerosol retrievals is significant and needs to be considered for future AOD retrievals using passive remote sensing techniques. Lastly, one year of MODIS and Advanced Microwave Scanning Radiometer - Earth Observing System (AMSR-E) data are used to investigate the impacts of oceanic bubble to the ESOA phenomenon. This study suggests that oceanic bubbles are not the major contributor to the ESOA feature.

  9. Trends in MODIS Geolocation Error Analysis

    NASA Technical Reports Server (NTRS)

    Wolfe, R. E.; Nishihama, Masahiro

    2009-01-01

    Data from the two MODIS instruments have been accurately geolocated (Earth located) to enable retrieval of global geophysical parameters. The authors describe the approach used to geolocate with sub-pixel accuracy over nine years of data from M0DIS on NASA's E0S Terra spacecraft and seven years of data from MODIS on the Aqua spacecraft. The approach uses a geometric model of the MODIS instruments, accurate navigation (orbit and attitude) data and an accurate Earth terrain model to compute the location of each MODIS pixel. The error analysis approach automatically matches MODIS imagery with a global set of over 1,000 ground control points from the finer-resolution Landsat satellite to measure static biases and trends in the MO0lS geometric model parameters. Both within orbit and yearly thermally induced cyclic variations in the pointing have been found as well as a general long-term trend.

  10. Seasonal evaluation of evapotranspiration fluxes from MODIS satellite and mesoscale model downscaled global reanalysis datasets

    NASA Astrophysics Data System (ADS)

    Srivastava, Prashant K.; Han, Dawei; Islam, Tanvir; Petropoulos, George P.; Gupta, Manika; Dai, Qiang

    2016-04-01

    Reference evapotranspiration (ETo) is an important variable in hydrological modeling, which is not always available, especially for ungauged catchments. Satellite data, such as those available from the MODerate Resolution Imaging Spectroradiometer (MODIS), and global datasets via the European Centre for Medium Range Weather Forecasts (ECMWF) reanalysis (ERA) interim and National Centers for Environmental Prediction (NCEP) reanalysis are important sources of information for ETo. This study explored the seasonal performances of MODIS (MOD16) and Weather Research and Forecasting (WRF) model downscaled global reanalysis datasets, such as ERA interim and NCEP-derived ETo, against ground-based datasets. Overall, on the basis of the statistical metrics computed, ETo derived from ERA interim and MODIS were more accurate in comparison to the estimates from NCEP for all the seasons. The pooled datasets also revealed a similar performance to the seasonal assessment with higher agreement for the ERA interim (r = 0.96, RMSE = 2.76 mm/8 days; bias = 0.24 mm/8 days), followed by MODIS (r = 0.95, RMSE = 7.66 mm/8 days; bias = -7.17 mm/8 days) and NCEP (r = 0.76, RMSE = 11.81 mm/8 days; bias = -10.20 mm/8 days). The only limitation with downscaling ERA interim reanalysis datasets using WRF is that it is time-consuming in contrast to the readily available MODIS operational product for use in mesoscale studies and practical applications.

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

    PubMed

    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

  12. Impacts of Reprojection and Sampling of MODIS Satellite Images on Estimating Crop Evapotranspiration Using METRIC model

    NASA Astrophysics Data System (ADS)

    Pun, M.; Kilic, A.; Allen, R.

    2014-12-01

    Landsat satellite images have been used frequently to map evapotranspiration (ET) andbiophysical variables at the field scale with surface energy balance algorithms. Although Landsat images have high spatial resolution with 30m cell size, it has limitations for real time monitoring of crop ET by providing only two to four images per month for an area, which, when encountered with cloudy days, further deteriorates the availability of images and snapshots of ET behavior. Therefore real time monitoring essentially has to include near-daily thermal satellites such as MODIS/VIIRS into the time series. However, the challenge with field scale monitoring with these systems is the large size of the thermal band which is 375 m with VIIRS and 1000 meter with MODIS. To maximize the accuracy of ET estimates during infusion of MODIS products into land surface models for monitoring field scale ET, it is important to assess the geometric accuracy of the various MODIS products, for example, spatial correspondence among the 250 m red and near-infrared bands, the 500 m reflectance bands; and the 1000 m thermal bands and associated products. METRIC model was used with MODIS images to estimate ET from irrigated and rainfed fields in Nebraska. Our objective was to assess geometric accuracy of MODIS image layers and how to correctly handle these data for highest accuracy of estimated ET at the individual field scale during the extensive drought of 2012. For example, the particular tool used to subset and reproject MODIS swath images from level-1 and level-2 products (e.g., using the MRTSwath and other tools), the initial starting location (upper left hand corner), and the projection system all effect how pixel corners of the various resolution bands align. Depending on the approach used, origin of pixel corners can vary from image to image date and therefore impacts the pairing of ET information from multiple dates the consistency and accuracy of sampling ET from within field interiors. Higher level MODIS products, including multi-day products, can have more consistent registration, but may suffer some compromisation of spatial fidelity due to the resampling required during various reprocessing steps.

  13. SatelliteDL - An IDL Toolkit for the Analysis of Satellite Earth Observations - GOES, MODIS, VIIRS and CERES

    NASA Astrophysics Data System (ADS)

    Fillmore, D. W.; Galloy, M. D.; Kindig, D.

    2013-12-01

    SatelliteDL is an IDL toolkit for the analysis of satellite Earth observations from a diverse set of platforms and sensors. The design features an abstraction layer that allows for easy inclusion of new datasets in a modular way. The core function of the toolkit is the spatial and temporal alignment of satellite swath and geostationary data. IDL has a powerful suite of statistical and visualization tools that can be used in conjunction with SatelliteDL. Our overarching objective is to create utilities that automate the mundane aspects of satellite data analysis, are extensible and maintainable, and do not place limitations on the analysis itself. Toward this end we have constructed SatelliteDL to include (1) HTML and LaTeX API document generation, (2) a unit test framework, (3) automatic message and error logs, (4) HTML and LaTeX plot and table generation, and (5) several real world examples with bundled datasets available for download. For ease of use, datasets, variables and optional workflows may be specified in a flexible format configuration file. Configuration statements may specify, for example, a region and date range, and the creation of images, plots and statistical summary tables for a long list of variables. SatelliteDL enforces data provenance; all data should be traceable and reproducible. The output NetCDF file metadata holds a complete history of the original datasets and their transformations, and a method exists to reconstruct a configuration file from this information. Release 0.1.0 of SatelliteDL is anticipated for the 2013 Fall AGU conference. It will distribute with ingest methods for GOES, MODIS, VIIRS and CERES radiance data (L1) as well as select 2D atmosphere products (L2) such as aerosol and cloud (MODIS and VIIRS) and radiant flux (CERES). Future releases will provide ingest methods for ocean and land surface products, gridded and time averaged datasets (L3 Daily, Monthly and Yearly), and support for 3D products such as temperature and water vapor profiles. Emphasis will be on NPP Sensor, Environmental and Climate Data Records as they become available. To obtain SatelliteDL (from 2013 December onward) please visit the project website at the indicated URL. Our poster exhibits three regional weather examples of SatelliteDL in action: (1) a mesoscale convective complex over the Great Plains (GOES, MODIS, VIIRS and CERES), (2) a dust storm over Arabia (MODIS, VIIRS and CERES) and (3) a volcanic ash plume over Patagonia and the South Atlantic (GOES, MODIS and CERES). In these examples the GOES radiances are cross-calibrated with MODIS. Cloud products are shown in examples (1) and (3) and aerosol products in examples (2) and (3).

  14. MODIS Land Data Products: Generation, Quality Assurance and Validation

    NASA Technical Reports Server (NTRS)

    Masuoka, Edward; Wolfe, Robert; Morisette, Jeffery; Sinno, Scott; Teague, Michael; Saleous, Nazmi; Devadiga, Sadashiva; Justice, Christopher; Nickeson, Jaime

    2008-01-01

    The Moderate Resolution Imaging Spectrometer (MODIS) on-board NASA's Earth Observing System (EOS) Terra and Aqua Satellites are key instruments for providing data on global land, atmosphere, and ocean dynamics. Derived MODIS land, atmosphere and ocean products are central to NASA's mission to monitor and understand the Earth system. NASA has developed and generated on a systematic basis a suite of MODIS products starting with the first Terra MODIS data sensed February 22, 2000 and continuing with the first MODIS-Aqua data sensed July 2, 2002. The MODIS Land products are divided into three product suites: radiation budget products, ecosystem products, and land cover characterization products. The production and distribution of the MODIS Land products are described, from initial software delivery by the MODIS Land Science Team, to operational product generation and quality assurance, delivery to EOS archival and distribution centers, and product accuracy assessment and validation. Progress and lessons learned since the first MODIS data were in early 2000 are described.

  15. Accessing and Understanding MODIS Data

    NASA Technical Reports Server (NTRS)

    Leptoukh, Gregory; Jenkerson, Calli B.; Jodha, Siri

    2003-01-01

    The National Aeronautics and Space Administration (NASA) launched the Terra satellite in December 1999, as part of the Earth Science Enterprise promotion of interdisciplinary studies of the integrated Earth system. Aqua, the second satellite from the series of EOS constellation, was launched in May 2002. Both satellites carry the MODerate resolution Imaging Spectroradiometer (MODIS) instrument. MODIS data are processed at the Goddard Space Flight Center, Greenbelt, MD, and then archived and distributed by the Distributed Active Archive Centers (DAACs). Data products from the MODIS sensors present new challenges to remote sensing scientists due to specialized production level, data format, and map projection. MODIS data are distributed as calibrated radiances and as higher level products such as: surface reflectance, water-leaving radiances, ocean color and sea surface temperature, land surface kinetic temperature, vegetation indices, leaf area index, land cover, snow cover, sea ice extent, cloud mask, atmospheric profiles, aerosol properties, and many other geophysical parameters. MODIS data are stored in HDF- EOS format in both swath format and in several different map projections. This tutorial guides users through data set characteristics as well as search and order interfaces, data unpacking, data subsetting, and potential applications of the data. A CD-ROM with sample data sets, and software tools for working with the data will be provided to the course participants.

  16. The EOS Aqua/Aura Experience: Lessons Learned on Design, Integration, and Test of Earth-Observing Satellites

    NASA Technical Reports Server (NTRS)

    Nosek, Thomas P.

    2004-01-01

    NASA and NOAA earth observing satellite programs are flying a number of sophisticated scientific instruments which collect data on many phenomena and parameters of the earth's environment. The NASA Earth Observing System (EOS) Program originated the EOS Common Bus approach, which featured two spacecraft (Aqua and Aura) of virtually identical design but with completely different instruments. Significant savings were obtained by the Common Bus approach and these lessons learned are presented as information for future program requiring multiple busses for new diversified instruments with increased capabilities for acquiring earth environmental data volume, accuracy, and type.

  17. Satellite-based automated burned area detection: A performance assessment of the MODIS MCD45A1 in the Brazilian savanna

    NASA Astrophysics Data System (ADS)

    Araújo, Fernando Moreira De; Ferreira, Laerte G.

    2015-04-01

    Burnings, which cause major changes to the environment, can be effectively monitored via satellite data, regarding both the identification of active fires and the estimation of burned areas. Among the many orbital sensors suitable for mapping burned areas on global and regional scales, the moderate resolution imaging spectroradiometer (MODIS), on board the Terra and Aqua platforms, has been the most widely utilized. In this study, the performance of the MODIS MCD45A1 burned area product was thoroughly evaluated in the Brazilian savanna, the second largest biome in South America and a global biodiversity hotspot, characterized by a conspicuous climatic seasonality and the systematic occurrence of natural and anthropogenic fires. Overall, September MCD45A1 polygons (2000-2012) compared well to the Landsat-based reference mapping (r2 = 0.92) and were closely accompanied, on a monthly basis, by MOD14 and MYD14 hotspots (r2 = 0.89), although large omissions errors, linked to landscape patterns, structures, and overall conditions depicted in each reference image, were observed. In spite of its spatial and temporal limitations, the MCD45A1 product proved instrumental for mapping and understanding fire behavior and impacts on the Cerrado landscapes.

  18. Performance of the Star Tracker Lightshades on the Earth Observing Satellite (EOS) Aqua

    NASA Technical Reports Server (NTRS)

    Kenney, Thomas; Schroeder, Michael; Donnelly, Michael; McNally, Mark; Bauer, Frank H. (Technical Monitor)

    2003-01-01

    The TRW built EOS Aqua spacecraft uses two Ball Aerospace CT-602 star trackers to provide attitude updates to the 3-axis, zero momentum, controller. Two months prior to the scheduled launch of Aqua, Ball reported an error in the design of the star tracker lightshades. The lightshades, which had been designed specifically for the EOS Common spacecraft, were not expected to meet the stray light rejection requirements of the mission and thus impact the overall spacecraft pointing performance. What ensued was an effort to characterize the actual performance of the existing shade design, determine what could be done within the physical envelope available, and modify the hardware to meet requirements. Changes were made based on this review activity and Aqua was launched on May 4, 2002. To date the spacecraft is meeting all of its science pointing requirements. Reported here are the lightshade design predictions, test results, and the measured on orbit performance of these shades.

  19. Performance of the Star Tracker Lightshades on the Earth Observing Satellite (EOS) Aqua

    NASA Technical Reports Server (NTRS)

    Kenny, Thomas; Lee, Albert; Donnelly, Michael; Schroder, Michael; McNally, Mark

    2003-01-01

    The TRW built EOS Aqua spacecraft uses two Ball Aerospace CT-602 star trackers to provide attitude updates to the 3-axis, zero momentum, controller. Two months prior to the scheduled launch of Aqua, Ball reported an error in the design of the star tracker lightshades. The lightshades, which had been designed specifically for the EOS Common spacecraft, were not expected to meet the stray light rejection requirements of the mission, thus impacting the overall spacecraft pointing performance. What ensued was an effort to characterize the actual performance of the existing shade design, determine what could be done within the physical envelope available, and modify the hardware to meet requirements. Changes were made based on this review activity and Aqua was launched on May 4, 2002. To date the spacecraft is meeting all of its science pointing requirements. Reported here are the lightshade design predictions, test results, and the measured on orbit performance of these shades.

  20. Aerosol radiative effects over global arid and semi-arid regions based on MODIS Deep Blue satellite observations

    NASA Astrophysics Data System (ADS)

    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 effect of aerosols at the top of atmosphere (TOA) fluxes (DRETOA), the atmospheric absorption of solar radiation (DREatmab) and the incoming and absorbed surface solar radiative fluxes (DREsurf and (DREnetsurf, respectively). The results are obtained for the period from January 2003 till December 2009, i.e. seven (7) years, on a monthly mean basis. The RTM results indicate that aerosols significantly enhance the absorbed solar radiation in the atmosphere, especially over the major deserts of Africa and Asia, by amounts ranging from 15 to 55 W/m2 (maximum values in Bodele, Sahara). On the other hand, through scattering and absorption, they decrease the surface absorption of solar radiation, by 10-45 W/m2 over the same areas, thus producing a significant surface radiative cooling. As a result of significant solar atmospheric absorption over the highly reflecting desert surface, aerosols decrease the reflected solar radiation to space, by up to 17 W m-2, producing a decrease of planetary albedo and an important planetary warming. Even larger values are obtained on a seasonal basis, while the average values of DREatmab and DREnetsurf over global land arid and semi-arid regions are equal to 8.9 and -11.3 W/m2, respectively. Significant intra- and inter-annual variations and changes of DREs are also identified.

  1. Vegetation monitoring for Guatemala: a comparison between simulated VIIRS and MODIS satellite data

    USGS Publications Warehouse

    Boken, Vijendra K.; Easson, Gregory L.; Rowland, James

    2010-01-01

    The advanced very high resolution radiometer (AVHRR) and moderate resolution imaging spectroradiometer (MODIS) data are being widely used for vegetation monitoring across the globe. However, sensors will discontinue collecting these data in the near future. National Aeronautics and Space Administration is planning to launch a new sensor, visible infrared imaging radiometer suite (VIIRS), to continue to provide satellite data for vegetation monitoring. This article presents a case study of Guatemala and compares the simulated VIIRS-Normalized Difference Vegetation Index (NDVI) with MODIS-NDVI for four different dates each in 2003 and 2005. The dissimilarity between VIIRS-NDVI and MODIS-NDVI was examined on the basis of the percent difference, the two-tailed student's t-test, and the coefficient of determination, R 2. The per cent difference was found to be within 3%, the p-value ranged between 0.52 and 0.99, and R 2 exceeded 0.88 for all major types of vegetation (basic grains, rubber, sugarcane, coffee and forests) found in Guatemala. It was therefore concluded that VIIRS will be almost equally capable of vegetation monitoring as MODIS.

  2. The regime of aerosol asymmetry parameter over Europe, the Mediterranean and the Middle East based on MODIS satellite data: evaluation against surface AERONET measurements

    NASA Astrophysics Data System (ADS)

    Korras-Carraca, M. B.; Hatzianastassiou, N.; Matsoukas, C.; Gkikas, A.; Papadimas, C. D.

    2015-11-01

    Atmospheric particulates are a significant forcing agent for the radiative energy budget of the Earth-atmosphere system. The particulates' interaction with radiation, which defines their climate effect, is strongly dependent on their optical properties. In the present work, we study one of the most important optical properties of aerosols, the asymmetry parameter (gaer), over sea surfaces of the region comprising North Africa, the Arabian Peninsula, Europe, and the Mediterranean Basin. These areas are of great interest, because of the variety of aerosol types they host, both anthropogenic and natural. Using satellite data from the collection 051 of MODIS (Moderate Resolution Imaging Spectroradiometer, Terra and Aqua), we investigate the spatiotemporal characteristics of the asymmetry parameter. We generally find significant spatial variability, with larger values over regions dominated by larger size particles, e.g., outside the Atlantic coasts of northwestern Africa, where desert-dust outflow takes place. The gaer values tend to decrease with increasing wavelength, especially over areas dominated by small particulates. The intra-annual variability is found to be small in desert-dust areas, with maximum values during summer, while in all other areas larger values are reported during the cold season and smaller during the warm. Significant intra-annual and inter-annual variability is observed around the Black Sea. However, the inter-annual trends of gaer are found to be generally small. Although satellite data have the advantage of broad geographical coverage, they have to be validated against reliable surface measurements. Therefore, we compare satellite-measured values with gaer values measured at 69 stations of the global surface AERONET (Aerosol Robotic Network), located within our region of interest. This way, we provide some insight on the quality and reliability of MODIS data. We report generally better agreement at the wavelength of 860 nm (correlation coefficient R up to 0.47), while at all wavelengths the results of the comparison were better for spring and summer.

  3. The regime of aerosol asymmetry parameter over Europe, Mediterranean and Middle East based on MODIS satellite data: evaluation against surface AERONET measurements

    NASA Astrophysics Data System (ADS)

    Korras-Carraca, M. B.; Hatzianastassiou, N.; Matsoukas, C.; Gkikas, A.; Papadimas, C. D.

    2014-09-01

    Atmospheric particulates are a significant forcing agent for the radiative energy budget of the Earth-atmosphere system. The particulates' interaction with radiation, which defines their climate effect, is strongly dependent on their optical properties. In the present work, we study one of the most important optical properties of aerosols, the asymmetry parameter (gaer), in the region comprised of North Africa, the Arabian peninsula, Europe, and the Mediterranean basin. These areas are of great interest, because of the variety of aerosol types they host, both anthropogenic and natural. Using satellite data from the collection 051 of MODIS (MODerate resolution Imaging Spectroradiometer, Terra and Aqua), we investigate the spatio-temporal characteristics of the asymmetry parameter. We generally find significant spatial variability, with larger values over regions dominated by larger size particles, e.g. outside the Atlantic coasts of north-western Africa, where desert-dust outflow is taking place. The gaer values tend to decrease with increasing wavelength, especially over areas dominated by small particulates. The intra-annual variability is found to be small in desert-dust areas, with maximum values during summer, while in all other areas larger values are reported during the cold season and smaller during the warm. Significant intra-annual and inter-annual variability is observed around the Black Sea. However, the inter-annual trends of gaer are found to be generally small. Although satellite data have the advantage of broad geographical coverage, they have to be validated against reliable surface measurements. Therefore, we compare satellite-based values with gaer values measured at 69 stations of the global surface network AERONET (Aerosol Robotic Network), located within our region of interest. This way, we provide some insight on the quality and reliability of MODIS data. We report generally better agreement at the wavelength of 870 nm (correlation coefficient R up to 0.47) while of all wavelengths the results of the comparison were better for spring and summer.

  4. A satellite remote sensing approach for mapping soil respiration and terrestrial carbon exchange for boreal and Arctic biomes using MODIS and AMSR-E

    NASA Astrophysics Data System (ADS)

    Kimball, J. S.; Jones, L. A.; McDonald, K. C.; Njoku, E. G.; Oechel, W. C.

    2006-12-01

    Boreal and Arctic ecosystems contain up to 40% of the global reservoir of soil carbon that is potentially reactive in the context of near-term climate change. We utilize synergistic information from MODIS and AMSR- E sensors onboard the NASA Aqua satellite within the framework of a simple carbon model to quantify soil respiration and land-atmosphere CO2 exchange (NEE) for boreal and Arctic biomes. AMSR-E multi- frequency, dual polarization microwave brightness temperatures are used to derive daily surface (<10cm) soil temperature and moisture constraints to soil heterotrophic respiration. MODIS LAI and GPP products provide vegetation biomass and productivity information, which is combined with AMSR-E results to calculate NEE at 8-day and annual intervals. Model results are compared across a regional network of tower eddy covariance flux tower sites spanning a diverse range of land cover and surface conditions. A sensitivity analysis is used to assess carbon model performance and response to uncertainties in the satellite remote sensing inputs. The satellite derived NEP results are found to be generally consistent with tower CO2 flux measurement and stand level ecosystem process model simulations of net photosynthesis, autotrophic and heterotrophic respiration, and NEE, capturing seasonal patterns and site differences in carbon fluxes. The carbon model response is also found to be primarily sensitive to LAI and soil temperature inputs, while model response to the observed range of soil moisture conditions is secondary. This work was performed at the University of Montana and Jet Propulsion Laboratory, California Institute of Technology under contract to NASA.

  5. Response to Toward Unified Satellite Climatology of Aerosol Properties. 3; MODIS versus MISR versus AERONET

    NASA Technical Reports Server (NTRS)

    Kahn, Ralph A.; Garay, Michael J.; Nelson, David L.; Levy, Robert C.; Bull, Michael A.; Diner, David J.; Martonchik, John V.; Hansen, Earl G.; Remer, Lorraine A.; Tanre, Didler

    2010-01-01

    A recent paper by Mishchenko et al. compares near-coincident MISR, MODIS, and AERONET aerosol optical depth (AOD), and gives a much less favorable impression of the utility of the satellite products than that presented by the instrument teams and other groups. We trace the reasons for the differing pictures to whether known and previously documented limitations of the products are taken into account in the assessments. Specifically, the analysis approaches differ primarily in (1) the treatment of outliers, (2) the application of absolute vs. relative criteria for testing agreement, and (3) the ways in which seasonally varying spatial distributions of coincident retrievals are taken into account. Mishchenko et al. also do not distinguish between observational sampling differences and retrieval algorithm error. We assess the implications of the different analysis approaches, and cite examples demonstrating how the MISR and MODIS aerosol products have been applied successfully to a range of scientific investigations.

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

    USGS Publications Warehouse

    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.

  7. Applications of MODIS satellite data and products for monitoring air quality in the state of Texas

    NASA Astrophysics Data System (ADS)

    Hutchison, Keith D.

    The Center for Space Research (CSR), in conjunction with the Monitoring Operations Division (MOD) of the Texas Commission on Environmental Quality (TCEQ), is evaluating the use of remotely sensed satellite data to assist in monitoring and predicting air quality in Texas. The challenges of meeting air quality standards established by the US Environmental Protection Agency (US EPA) are impacted by the transport of pollution into Texas that originates from outside our borders and are cumulative with those generated by local sources. In an attempt to quantify the concentrations of all pollution sources, MOD has installed ground-based monitoring stations in rural regions along the Texas geographic boundaries including the Gulf coast, as well as urban regions that are the predominant sources of domestic pollution. However, analysis of time-lapse GOES satellite imagery at MOD, clearly demonstrates the shortcomings of using only ground-based observations for monitoring air quality across Texas. These shortcomings include the vastness of State borders, that can only be monitored with a large number of ground-based sensors, and gradients in pollution concentration that depend upon the location of the point source, the meteorology governing its transport to Texas, and its diffusion across the region. With the launch of NASA's MODerate resolution Imaging Spectroradiometer (MODIS), the transport of aerosol-borne pollutants can now be monitored over land and ocean surfaces. Thus, CSR and MOD personnel have applied MODIS data to several classes of pollution that routinely impact Texas air quality. Results demonstrate MODIS data and products can detect and track the migration of pollutants. This paper presents one case study in which continental haze from the northeast moved into the region and subsequently required health advisories to be issued for 150 counties in Texas. It is concluded that MODIS provides the basis for developing advanced data products that will, when used in conjunction with ground-based observations, create a cost-effective and accurate pollution monitoring system for the entire state of Texas.

  8. Snow cover retrieval over Rhone and Po river basins from MODIS optical satellite data (2000-2009).

    NASA Astrophysics Data System (ADS)

    Dedieu, Jean-Pierre, ,, Dr.; Boos, Alain; Kiage, Wiliam; Pellegrini, Matteo

    2010-05-01

    Estimation of the Snow Covered Area (SCA) is an important issue for meteorological application and hydrological modeling of runoff. With spectral bands in the visible, near and middle infrared, the MODIS optical satellite sensor can be used to detect snow cover because of large differences between reflectance from snow covered and snow free surfaces. At the same time, it allows separation between snow and clouds. Moreover, the sensor provides a daily coverage of large areas (2,500 km range). However, as the pixel size is 500m x 500m, a MODIS pixel may be partially covered by snow, particularly in Alpine areas, where snow may not be present in valleys lying at lower altitudes. Also, variation of reflectance due to differential sunlit effects as a function of slope and aspect, as well as bidirectional effects may be present in images. Nevertheless, it is possible to estimate snow cover at the Sub-Pixel level with a relatively good accuracy and with very good results if the sub-pixel estimations are integrated for a few pixels relative to an entire watershed. Integrated into the EU-FP7 ACQWA Project (www.acqwa.ch), this approach was first applied over Alpine area of Rhone river basin upper Geneva Lake: Canton du Valais, Switzerland (5 375 km²). In a second step over Alps, rolling hills and plain areas in Po catchment for Val d'Aosta and Piemonte regions, Italy (37 190 km²). Watershed boundaries were provided respectively by GRID (Ch) and ARPA (It) partners. The complete satellite images database was extracted from the U.S. MODIS/NASA website (http://modis.gsfc.nasa.gov/) for MOD09_B1 Reflectance images, and from the MODIS/NSIDC website (http://nsidc.org/index.html) for MOD10_A2 snow cover images. Only the Terra platform was used because images are acquired in the morning and are therefore better correlated with dry snow surface, avoiding cloud coverage of the afternoon (Aqua Platform). The MOD9 Image reflectance and MOD10_A2 products were respectively analyzed to retrieve (i) Fractional Snow cover at sub-pixel scale, and (ii) maximum snow cover. All products were retrieved at 8-days over a complete time period of 10 years (2000-2009), giving 500 images for each river basin. Digital Model Elevation was given by NASA/SRTM database at 90-m resolution and used (i) for illumination versus topography correction on snow cover, (ii) geometric rectification of images. Geographic projection is WGS84, UTM 32. Fractional Snow cover mapping was derived from the NDSI linear regression method (Salomonson et al., 2004). Cloud mask was given by MODIS-NASA library (radiometric threshold) and completed by inverse slope regression to avoid lowlands fog confusing with thin snow cover (Po river basin). Maximum Snow Cover mapping was retrieved from the NSIDC database classification (Hall et al., 2001). Validation step was processed using comparison between MODIS Snow maps outputs and meteorological data provided by network of 87 meteorological stations: temperature, precipitation, snow depth measurement. A 0.92 correlation was observed for snow/non snow cover and can be considered as quite satisfactory, given the radiometric problems encountered in mountainous areas, particularly in snowmelt season. The 10-years time period results indicates a main difference between (i) regular snow accumulation and depletion in Rhone and (ii) the high temporal and spatial variability of snow cover for Po. Then, a high sensitivity to low variation of air temperature, often close to 1° C was observed. This is the case in particular for the beginning and the end of the winter season. The regional snow cover depletion is both influenced by thermal positives anomalies (e.g. 2000 and 2006), and the general trend of rising atmospheric temperatures since the late 1980s, particularly for Po river basin. Results will be combined with two hydrological models: Topkapi and Fest.

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

    NASA Astrophysics Data System (ADS)

    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.

  10. Intercalibration of Meteorological Satellite Imagers Using AVHRR, VIRS, ATSR-2, and MODIS

    NASA Astrophysics Data System (ADS)

    Nguyen, L.; Minnis, P.; Ayers, J. K.; Doelling, D. R.; Smith, W. L.; Dong, X.

    2001-05-01

    Accurate and timely calibrations of satellite imager sensors are critical for remote sensing of the surface and atmosphere. A technique has been developed to routinely intercalibrate and normalize the imager channels onboard geostationary (GEO) and low-Earth-orbit (LEO) satellites. As a reference calibration source, this technique uses self-calibrating sensors from the Tropical Rainfall Measuring Mission (TRMM) Visible Infrared Radiometers (VIRS), the ERS-2 Along Track Scanning Radiometer (ATSR-2) and the TERRA Moderate Resolution Imaging Spectroradiometer (MODIS). GOES-8 is first calibrated using VIRS and verified with the ATSR-2. This calibration is then transferred to the NOAA-14 Advanced Very High Resolution Radiometer (AVHRR) that is subsequently used as an additional reference to calibrate other GEO or LEO satellites. These GEO or LEO satellites can then be used as transfer media to calibrate other satellites including the Geostationary Meteorological Satellite (GMS), Meteosat, GOES, NOAA-12, NOAA-15 and NOAA-16. The technique matches collocated data with similar view, solar and relative azimuth angles. This paper discusses the calibration of the visible and infrared channels from 6 years of GOES-8 data and the accuracy of secondary calibration transfers. The absolute accuracies of the visible calibrations are examined by comparing stratus cloud optical depth retrievals from the surface at the Atmospheric Radiation Measurement (ARM) Southern Great Plains site.

  11. eMODIS: A User-Friendly Data Source

    USGS Publications Warehouse

    Jenkerson, Calli; Maiersperger, Thomas; Schmidt, Gail

    2010-01-01

    The U.S. Geological Survey's (USGS) Earth Resources Observation and Science (EROS) Center is generating a suite of products called 'eMODIS' based on Moderate Resolution Imaging Spectroradiometer (MODIS) data acquired by the National Aeronautics and Space Administration's (NASA) Earth Observing System (EOS). With a more frequent repeat cycle than Landsat and higher spatial resolutions than the Advanced Very High Resolution Spectroradiometer (AVHRR), MODIS is well suited for vegetation studies. For operational monitoring, however, the benefits of MODIS are counteracted by usability issues with the standard map projection, file format, composite interval, high-latitude 'bow-tie' effects, and production latency. eMODIS responds to a community-specific need for alternatively packaged MODIS data, addressing each of these factors for real-time monitoring and historical trend analysis. eMODIS processes calibrated radiance data (level-1B) acquired by the MODIS sensors on the EOS Terra and Aqua satellites by combining MODIS Land Science Collection 5 Atmospherically Corrected Surface Reflectance production code and USGS EROS MODIS Direct Broadcast System (DBS) software to create surface reflectance and Normalized Difference Vegetation Index (NDVI) products. eMODIS is produced over the continental United States and over Alaska extending into Canada to cover the Yukon River Basin. The 250-meter (m), 500-m, and 1,000-m products are delivered in Geostationary Earth Orbit Tagged Image File Format (Geo- TIFF) and composited in 7-day intervals. eMODIS composites are projected to non-Sinusoidal mapping grids that best suit the geography in their areas of application (see eMODIS Product Description below). For eMODIS products generated over the continental United States (eMODIS CONUS), the Terra (from 2000) and Aqua (from 2002) records are available and continue through present time. eMODIS CONUS also is generated in an expedited process that delivers a 7-day rolling composite, created daily with the most recent 7 days of acquisition, to users monitoring real-time vegetation conditions. eMODIS Alaska is not part of expedited processing, but does cover the Terra mission life (2000-present). A simple file transfer protocol (FTP) distribution site currently is enabled on the Internet for direct download of eMODIS products (ftp://emodisftp.cr.usgs.gov/eMODIS), with plans to expand into an interactive portal environment.

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

    SciTech Connect

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

    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.

  13. Atmospheric Correction of High-Spatial-Resolution Commercial Satellite Imagery Products Using MODIS Atmospheric Products

    NASA Technical Reports Server (NTRS)

    Pagnutti, Mary; Holekamp, Kara; Ryan, Robert E.; Vaughan, Ronand; Russell, Jeff; Prados, Don; Stanley, Thomas

    2005-01-01

    Remotely sensed ground reflectance is the foundation of any interoperability or change detection technique. Satellite intercomparisons and accurate vegetation indices, such as the Normalized Difference Vegetation Index (NDVI), require the generation of accurate reflectance maps (NDVI is used to describe or infer a wide variety of biophysical parameters and is defined in terms of near-infrared (NIR) and red band reflectances). Accurate reflectance-map generation from satellite imagery relies on the removal of solar and satellite geometry and of atmospheric effects and is generally referred to as atmospheric correction. Atmospheric correction of remotely sensed imagery to ground reflectance has been widely applied to a few systems only. The ability to obtain atmospherically corrected imagery and products from various satellites is essential to enable widescale use of remotely sensed, multitemporal imagery for a variety of applications. An atmospheric correction approach derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) that can be applied to high-spatial-resolution satellite imagery under many conditions was evaluated to demonstrate a reliable, effective reflectance map generation method. Additional information is included in the original extended abstract.

  14. Moisture Fluxes Derived from EOS Aqua Satellite Data for the North Water Polynya Over 2003-2009

    NASA Technical Reports Server (NTRS)

    Boisvert, Linette N.; Markus, Thorsten; Parkinson, Claire L.; Vihma, Timo

    2012-01-01

    Satellite data were applied to calculate the moisture flux from the North Water polynya during a series of events spanning 2003-2009. The fluxes were calculated using bulk aerodynamic formulas with the stability effects according to the Monin-Obukhov similarity theory. Input parameters were taken from three sources: air relative humidity, air temperature, and surface temperature from the Atmospheric Infrared Sounder (AIRS) onboard NASA's Earth Observing System (EOS) Aqua satellite, sea ice concentration from the Advanced Microwave Scanning Radiometer (AMSR-E, also onboard Aqua), and wind speed from the ECMWF ERA-Interim reanalysis. Our results show the progression of the moisture fluxes from the polynya during each event, as well as their atmospheric effects after the polynya has closed up. These results were compared to results from studies on other polynyas, and fall within one standard deviation of the moisture flux estimates from these studies. Although the estimated moisture fluxes over the entire study region from AIRS are smaller in magnitude than ERA-Interim, they are more accurate due to improved temperature and relative humidity profiles and ice concentration estimates over the polynya. Error estimates were calculated to be 5.56 x10(exp -3) g/sq. m/ s, only 25% of the total moisture flux, thus suggesting that AIRS and AMSR-E can be used with confidence to study smaller scale features in the Arctic sea ice pack and can capture their atmospheric effects. These findings bode well for larger-scale studies of moisture fluxes over the entire Arctic Ocean and the thinning ice pack.

  15. Comparison of MODIS and PLEIADES Lunar observations

    NASA Astrophysics Data System (ADS)

    Xiong, Xiaoxiong; Lachérade, Sophie; Lebègue, Laurent; Fougnie, Bertrand; Angal, Amit; Wang, Zhipeng; Aznay, Ouahid

    2014-10-01

    MODIS is the key instrument for the NASA's EOS Terra and Aqua missions, launched in late 1999 and early 2002, respectively. MODIS has 20 reflective solar bands (RSB) and 16 thermal emissive bands (TEB). MODIS RSB are calibrated on-orbit using an on-board solar diffuser and regularly scheduled lunar observations. For each instrument, the scheduled lunar observations are made through its space view (SV) port at nearly identical lunar phase angles via spacecraft roll maneuvers. Occasionally, unscheduled lunar observations at different phase angles are also collected by both Terra and Aqua MODIS. The PLEIADES system is composed of two satellites, PLEIADES-1A launched at the end of 2011 and PLEIADES-1B a year later. The PLEIADES has 5 reflective solar bands or channels (blue, green, red, nearinfrared, and panchromatic) that are calibrated on-orbit using observations of Pseudo Invariant Calibration Sites (PICS). Since launch, more than 1000 lunar images covering the phase angle range of ±115° have been acquired by PLEIADES- 1B for its on-orbit calibration and sensitivity study of lunar calibration methods. This paper provides an overview of MODIS and PLEIADES lunar observations and an assessment of their calibration difference based on lunar observations made over a range of phase angles. Also discussed in this paper are strategies and future effort that could potentially benefit other earth observing sensors and improve the calibration accuracy and consistency of existing lunar model(s).

  16. Detection of Burn Area and Severity with MODIS Satellite Images and Spatial Autocorrelation Techniques

    NASA Astrophysics Data System (ADS)

    Kaya, S.; Kavzoglu, T.; Tonbul, H.

    2014-12-01

    Effects of forest fires and implications are one of the most important natural disasters all over the world. Statistical data observed that forest fires had a variable structure in the last century in Turkey, but correspondingly the population growth amount of forest fires and burn area increase widely in recent years. Depending on this, erosion, landslides, desertification and mass loss come into existence. In addition; after forest fires, renewal of forests and vegetation are very important for land management. Classic methods used for detection of burn area and severity requires a long and challenging process due to time and cost factors. Thanks to advanced techniques used in the field of Remote Sensing, burn area and severity can be determined with high detail and precision. The purpose of this study based on blending MODIS (Moderate Resolution Imaging Spectradiometer) satellite images and spatial autocorrelation techniques together, thus detect burn area and severity absolutely. In this context, spatial autocorrelation statistics like Moran's I and Get is-Ord Local Gi indexes were used to measure and analyze to burned area characteristics. Prefire and postfire satellite images were used to determine fire severity depending on spectral indexes corresponding to biomass loss and carbon emissivity intensities. Satellite images have used for identification of fire damages and risks in terms of fire management for a long time. This study was performed using prefire and postfire satellite images and spatial autocorrelation techniques to determining and analyzing forest fires in Antalya, Turkey region which serious fires occurred. In this context, this approach enables the characterization of distinctive texture of burned area and helps forecasting more precisely. Finally, it is observed that mapping of burned area and severity could be performed from local scale to national scale. Key Words: Spatial autocorrelation, MODIS, Fire, Burn Severity

  17. Contribution of MODIS satellite imagery in modelling the flooding patterns of the coastal wetlands of the Tana River, Kenya

    NASA Astrophysics Data System (ADS)

    Leauthaud, C.; Duvail, S.; Belaud, G.; Albergel, J.; Moussa, R.; Grunberger, O.

    2012-04-01

    In sub-Saharan Africa, much of the arid and semi-arid lands are used by pastoralist groups as seasonal grazing zones. In such a context, wetlands are a vital resource as they act as retreat zones during the dry seasons when water and fodder resources are scarce. At a larger scale, wetlands also render numerous services including groundwater recharge, water quality improvement and climate regulation. As regular floods are the underlying factor determining the healthiness of wetland ecosystems, it is important to understand their dynamics for a better water resource management at the catchment scale in the context of increased water abstraction and hydroelectric infrastructure development. Yet, this is challenging in many places because of scarce or poor quality data and a often difficult access to the zone. In tropical or coastal areas, frequent cloud cover can also limit the use of remote sensing data. The MODIS instruments on board the Terra and Aqua satellites offer high temporal resolution images at a moderate spatial resolution in the visible and infrared spectrum. In particular the MOD09A1 and MYD09A1 500m, 8-day synthesis products select the best possible observation for each 8-day period thus decreasing poor quality pixels due to cloud cover in an image while retaining a high frequency coverage. Here we assess their potential use to monitor floods in the Tana River Delta (TRD), Kenya. In this study, all 8-day synthesis products from 2001 to 2011 were screened and selected for low cloud cover. The total flooded surface was then extracted from each image using the Normalized Difference Moisture Index (Xu, 2006) to obtain time-series inundation maps from 2002 onward. In a third step, the images were used, combined with river-flow data, to analyse the hydrological system of the area. The maximal extent, start and end inundation dates were determined for the major floods of the past decade. There were major differences in these characteristics for medium to large-scale flooding as well as differences between the long and short rainy-seasons. We also show that the total flooded surface was mainly correlated to upstream river-flow data and not local rainfall nor evaporation. The inundation maps were then used to construct a simplified hydrological model of the zone in order to 1/ further characterize the major processes that determine flood extent and duration and 2/ assess whether there have been temporal and spatial changes of the latter in the past decade. As such, MODIS products have proved useful in understanding the seasonal inundation dynamics in the TRD. The calibrated hydrological model will provide insight on how new hydroelectric infrastructure will impact the water resources and the associated ecosystem services of the delta. These high temporal and medium-range spatial resolution satellite imagery provide a free-of-cost and rapid solution in monitoring water distribution and environmental changes in tropical, coastal or semi-arid areas.

  18. CERES Single Scanner Satellite Footprint, TOA, Surface Fluxes and Clouds (SSF) data in HDF (CER_SSF_Terra-FM1-MODIS_Edition2A)

    NASA Technical Reports Server (NTRS)

    Wielicki, Bruce A. (Principal Investigator)

    The Single Scanner Footprint TOA/Surface Fluxes and Clouds (SSF) product contains one hour of instantaneous Clouds and the Earth's Radiant Energy System (CERES) data for a single scanner instrument. The SSF combines instantaneous CERES data with scene information from a higher-resolution imager such as Visible/Infrared Scanner (VIRS) on TRMM or Moderate-Resolution Imaging Spectroradiometer (MODIS) on Terra and Aqua. Scene identification and cloud properties are defined at the higher imager resolution and these data are averaged over the larger CERES footprint. For each CERES footprint, the SSF contains the number of cloud layers and for each layer the cloud amount, height, temperature, pressure, optical depth, emissivity, ice and liquid water path, and water particle size. The SSF also contains the CERES filtered radiances for the total, shortwave (SW), and window (WN) channels and the unfiltered SW, longwave (LW), and WN radiances. The SW, LW, and WN radiances at spacecraft altitude are converted to Top-of-the-Atmosphere (TOA) fluxes based on the imager defined scene. These TOA fluxes are used to estimate surface fluxes. Only footprints with adequate imager coverage are included on CER_SSF_TRMM-PFM-VIRS_Subset_Edition1the SSF which is much less than the full set of footprints on the CERES ES-8 product. The following CERES SSF data sets are currently available: CER_SSF_TRMM-PFM-VIRS_Edition1 CER_SSF_TRMM-PFM-VIRS_Subset_Edition1 CER_SSF_TRMM-PFM-VIRS_Edition2A CER_SSF_TRMM-SIM-VIRS_Edition2_VIRSonly CER_SSF_TRMM-PFM-VIRS_Edition2A-TransOps CER_SSF_TRMM-PFM-VIRS_Edition2B-TransOps CER_SSF_TRMM-PFM-VIRS_Edition2B CER_SSF_Terra-FM1-MODIS_Edition1A CER_SSF_Terra-FM1-MODIS_Edition1A CER_SSF_Terra-FM1-MODIS_Edition2A CER_SSF_Terra-FM2-MODIS_Edition2A CER_SSF_Terra-FM1-MODIS_Edition2B CER_SSF_Terra-FM2-MODIS_Edition2B CER_SSF_Aqua-FM4-MODIS_Beta1 CER_SSF_Aqua-FM3-MODIS_Beta2 CER_SSF_Aqua-FM4-MODIS_Beta2. [Location=GLOBAL] [Temporal_Coverage: Start_Date=1998-01-01; Stop_Date=2003-12-31] [Spatial_Coverage: Southernmost_Latitude=-90; Northernmost_Latitude=90; Westernmost_Longitude=-180; Easternmost_Longitude=180] [Data_Resolution: Temporal_Resolution=1 hour; Temporal_Resolution_Range=Hourly - < Daily].

  19. CERES Single Scanner Satellite Footprint, TOA, Surface Fluxes and Clouds (SSF) data in HDF (CER_SSF_Terra-FM2-MODIS_Edition2A)

    NASA Technical Reports Server (NTRS)

    Wielicki, Bruce A. (Principal Investigator)

    The Single Scanner Footprint TOA/Surface Fluxes and Clouds (SSF) product contains one hour of instantaneous Clouds and the Earth's Radiant Energy System (CERES) data for a single scanner instrument. The SSF combines instantaneous CERES data with scene information from a higher-resolution imager such as Visible/Infrared Scanner (VIRS) on TRMM or Moderate-Resolution Imaging Spectroradiometer (MODIS) on Terra and Aqua. Scene identification and cloud properties are defined at the higher imager resolution and these data are averaged over the larger CERES footprint. For each CERES footprint, the SSF contains the number of cloud layers and for each layer the cloud amount, height, temperature, pressure, optical depth, emissivity, ice and liquid water path, and water particle size. The SSF also contains the CERES filtered radiances for the total, shortwave (SW), and window (WN) channels and the unfiltered SW, longwave (LW), and WN radiances. The SW, LW, and WN radiances at spacecraft altitude are converted to Top-of-the-Atmosphere (TOA) fluxes based on the imager defined scene. These TOA fluxes are used to estimate surface fluxes. Only footprints with adequate imager coverage are included on CER_SSF_TRMM-PFM-VIRS_Subset_Edition1the SSF which is much less than the full set of footprints on the CERES ES-8 product. The following CERES SSF data sets are currently available: CER_SSF_TRMM-PFM-VIRS_Edition1 CER_SSF_TRMM-PFM-VIRS_Subset_Edition1 CER_SSF_TRMM-PFM-VIRS_Edition2A CER_SSF_TRMM-SIM-VIRS_Edition2_VIRSonly CER_SSF_TRMM-PFM-VIRS_Edition2A-TransOps CER_SSF_TRMM-PFM-VIRS_Edition2B-TransOps CER_SSF_TRMM-PFM-VIRS_Edition2B CER_SSF_Terra-FM1-MODIS_Edition1A CER_SSF_Terra-FM1-MODIS_Edition1A CER_SSF_Terra-FM1-MODIS_Edition2A CER_SSF_Terra-FM2-MODIS_Edition2A CER_SSF_Terra-FM1-MODIS_Edition2B CER_SSF_Terra-FM2-MODIS_Edition2B CER_SSF_Aqua-FM4-MODIS_Beta1 CER_SSF_Aqua-FM3-MODIS_Beta2 CER_SSF_Aqua-FM4-MODIS_Beta2. [Location=GLOBAL] [Temporal_Coverage: Start_Date=1998-01-01; Stop_Date=2003-12-31] [Spatial_Coverage: Southernmost_Latitude=-90; Northernmost_Latitude=90; Westernmost_Longitude=-180; Easternmost_Longitude=180] [Data_Resolution: Temporal_Resolution=1 hour; Temporal_Resolution_Range=Hourly - < Daily].

  20. CERES Single Scanner Satellite Footprint, TOA, Surface Fluxes and Clouds (SSF) data in HDF (CER_SSF_Terra-FM1-MODIS_Edition1A)

    NASA Technical Reports Server (NTRS)

    Wielicki, Bruce A. (Principal Investigator)

    The Single Scanner Footprint TOA/Surface Fluxes and Clouds (SSF) product contains one hour of instantaneous Clouds and the Earth's Radiant Energy System (CERES) data for a single scanner instrument. The SSF combines instantaneous CERES data with scene information from a higher-resolution imager such as Visible/Infrared Scanner (VIRS) on TRMM or Moderate-Resolution Imaging Spectroradiometer (MODIS) on Terra and Aqua. Scene identification and cloud properties are defined at the higher imager resolution and these data are averaged over the larger CERES footprint. For each CERES footprint, the SSF contains the number of cloud layers and for each layer the cloud amount, height, temperature, pressure, optical depth, emissivity, ice and liquid water path, and water particle size. The SSF also contains the CERES filtered radiances for the total, shortwave (SW), and window (WN) channels and the unfiltered SW, longwave (LW), and WN radiances. The SW, LW, and WN radiances at spacecraft altitude are converted to Top-of-the-Atmosphere (TOA) fluxes based on the imager defined scene. These TOA fluxes are used to estimate surface fluxes. Only footprints with adequate imager coverage are included on CER_SSF_TRMM-PFM-VIRS_Subset_Edition1the SSF which is much less than the full set of footprints on the CERES ES-8 product. The following CERES SSF data sets are currently available: CER_SSF_TRMM-PFM-VIRS_Edition1 CER_SSF_TRMM-PFM-VIRS_Subset_Edition1 CER_SSF_TRMM-PFM-VIRS_Edition2A CER_SSF_TRMM-SIM-VIRS_Edition2_VIRSonly CER_SSF_TRMM-PFM-VIRS_Edition2A-TransOps CER_SSF_TRMM-PFM-VIRS_Edition2B-TransOps CER_SSF_TRMM-PFM-VIRS_Edition2B CER_SSF_Terra-FM1-MODIS_Edition1A CER_SSF_Terra-FM1-MODIS_Edition1A CER_SSF_Terra-FM1-MODIS_Edition2A CER_SSF_Terra-FM2-MODIS_Edition2A CER_SSF_Terra-FM1-MODIS_Edition2B CER_SSF_Terra-FM2-MODIS_Edition2B CER_SSF_Aqua-FM4-MODIS_Beta1 CER_SSF_Aqua-FM3-MODIS_Beta2 CER_SSF_Aqua-FM4-MODIS_Beta2. [Location=GLOBAL] [Temporal_Coverage: Start_Date=1998-01-01; Stop_Date=2002-10-31] [Spatial_Coverage: Southernmost_Latitude=-90; Northernmost_Latitude=90; Westernmost_Longitude=-180; Easternmost_Longitude=180] [Data_Resolution: Temporal_Resolution=1 hour; Temporal_Resolution_Range=Hourly - < Daily].

  1. CERES Single Scanner Satellite Footprint, TOA, Surface Fluxes and Clouds (SSF) data in HDF (CER_SSF_Terra-FM2-MODIS_Edition2B)

    NASA Technical Reports Server (NTRS)

    Wielicki, Bruce A. (Principal Investigator)

    The Single Scanner Footprint TOA/Surface Fluxes and Clouds (SSF) product contains one hour of instantaneous Clouds and the Earth's Radiant Energy System (CERES) data for a single scanner instrument. The SSF combines instantaneous CERES data with scene information from a higher-resolution imager such as Visible/Infrared Scanner (VIRS) on TRMM or Moderate-Resolution Imaging Spectroradiometer (MODIS) on Terra and Aqua. Scene identification and cloud properties are defined at the higher imager resolution and these data are averaged over the larger CERES footprint. For each CERES footprint, the SSF contains the number of cloud layers and for each layer the cloud amount, height, temperature, pressure, optical depth, emissivity, ice and liquid water path, and water particle size. The SSF also contains the CERES filtered radiances for the total, shortwave (SW), and window (WN) channels and the unfiltered SW, longwave (LW), and WN radiances. The SW, LW, and WN radiances at spacecraft altitude are converted to Top-of-the-Atmosphere (TOA) fluxes based on the imager defined scene. These TOA fluxes are used to estimate surface fluxes. Only footprints with adequate imager coverage are included on CER_SSF_TRMM-PFM-VIRS_Subset_Edition1the SSF which is much less than the full set of footprints on the CERES ES-8 product. The following CERES SSF data sets are currently available: CER_SSF_TRMM-PFM-VIRS_Edition1 CER_SSF_TRMM-PFM-VIRS_Subset_Edition1 CER_SSF_TRMM-PFM-VIRS_Edition2A CER_SSF_TRMM-SIM-VIRS_Edition2_VIRSonly CER_SSF_TRMM-PFM-VIRS_Edition2A-TransOps CER_SSF_TRMM-PFM-VIRS_Edition2B-TransOps CER_SSF_TRMM-PFM-VIRS_Edition2B CER_SSF_Terra-FM1-MODIS_Edition1A CER_SSF_Terra-FM1-MODIS_Edition1A CER_SSF_Terra-FM1-MODIS_Edition2A CER_SSF_Terra-FM2-MODIS_Edition2A CER_SSF_Terra-FM1-MODIS_Edition2B CER_SSF_Terra-FM2-MODIS_Edition2B CER_SSF_Aqua-FM4-MODIS_Beta1 CER_SSF_Aqua-FM3-MODIS_Beta2 CER_SSF_Aqua-FM4-MODIS_Beta2. [Location=GLOBAL] [Temporal_Coverage: Start_Date=1998-01-01; Stop_Date=2006-01-01] [Spatial_Coverage: Southernmost_Latitude=-90; Northernmost_Latitude=90; Westernmost_Longitude=-180; Easternmost_Longitude=180] [Data_Resolution: Temporal_Resolution=1 hour; Temporal_Resolution_Range=Hourly - < Daily].

  2. CERES Single Scanner Satellite Footprint, TOA, Surface Fluxes and Clouds (SSF) data in HDF (CER_SSF_Terra-FM1-MODIS_Edition2B)

    NASA Technical Reports Server (NTRS)

    Wielicki, Bruce A. (Principal Investigator)

    The Single Scanner Footprint TOA/Surface Fluxes and Clouds (SSF) product contains one hour of instantaneous Clouds and the Earth's Radiant Energy System (CERES) data for a single scanner instrument. The SSF combines instantaneous CERES data with scene information from a higher-resolution imager such as Visible/Infrared Scanner (VIRS) on TRMM or Moderate-Resolution Imaging Spectroradiometer (MODIS) on Terra and Aqua. Scene identification and cloud properties are defined at the higher imager resolution and these data are averaged over the larger CERES footprint. For each CERES footprint, the SSF contains the number of cloud layers and for each layer the cloud amount, height, temperature, pressure, optical depth, emissivity, ice and liquid water path, and water particle size. The SSF also contains the CERES filtered radiances for the total, shortwave (SW), and window (WN) channels and the unfiltered SW, longwave (LW), and WN radiances. The SW, LW, and WN radiances at spacecraft altitude are converted to Top-of-the-Atmosphere (TOA) fluxes based on the imager defined scene. These TOA fluxes are used to estimate surface fluxes. Only footprints with adequate imager coverage are included on CER_SSF_TRMM-PFM-VIRS_Subset_Edition1the SSF which is much less than the full set of footprints on the CERES ES-8 product. The following CERES SSF data sets are currently available: CER_SSF_TRMM-PFM-VIRS_Edition1 CER_SSF_TRMM-PFM-VIRS_Subset_Edition1 CER_SSF_TRMM-PFM-VIRS_Edition2A CER_SSF_TRMM-SIM-VIRS_Edition2_VIRSonly CER_SSF_TRMM-PFM-VIRS_Edition2A-TransOps CER_SSF_TRMM-PFM-VIRS_Edition2B-TransOps CER_SSF_TRMM-PFM-VIRS_Edition2B CER_SSF_Terra-FM1-MODIS_Edition1A CER_SSF_Terra-FM1-MODIS_Edition1A CER_SSF_Terra-FM1-MODIS_Edition2A CER_SSF_Terra-FM2-MODIS_Edition2A CER_SSF_Terra-FM1-MODIS_Edition2B CER_SSF_Terra-FM2-MODIS_Edition2B CER_SSF_Aqua-FM4-MODIS_Beta1 CER_SSF_Aqua-FM3-MODIS_Beta2 CER_SSF_Aqua-FM4-MODIS_Beta2. [Location=GLOBAL] [Temporal_Coverage: Start_Date=1998-01-01; Stop_Date=2005-12-31] [Spatial_Coverage: Southernmost_Latitude=-90; Northernmost_Latitude=90; Westernmost_Longitude=-180; Easternmost_Longitude=180] [Data_Resolution: Temporal_Resolution=1 hour; Temporal_Resolution_Range=Hourly - < Daily].

  3. Navy Exploitation of SeaWiFS and MODIS Satellite Imagery for Detection of Desert Dust Storms Over Land and Water

    NASA Astrophysics Data System (ADS)

    Miller, S. D.

    2002-12-01

    The United States Navy gives serious consideration to the subject of dust detection. In a recent study of Naval aviation mishaps over the period 1990-1998 (Cantu, 2001), it was found that 70% were associated with visibility problems and accounted for annual equipment losses of nearly 50 million dollars. This figure does not include the tax dollars lost in jettisoned or off-target ordnance owing to obscured targets or failure of laser-guided systems in the presence of significant dust. Nor can it account for the loss of life during a subset of these mishaps. As such, a strong research emphasis has been placed on detecting and quantifying dust over data-sparse/denied parts of the world. The prolific and complex dust climatology of Southwest Asia has posed considerable challenges to Navy operations over the course of Operation Enduring Freedom. In an effort to support the ongoing needs of the Meteorology/Oceanography (METOC) officers afloat, the Satellite Applications Section of the Naval Research Laboratory (NRL) Marine Meteorology Division has developed a novel approach to enhancing significant dust events that appeals to high spatial and spectral resolution satellite data currently available from state of the art ocean/atmospheric radiometers. This paper summarizes progress made on daytime enhancements of desert dust storms over both land and ocean using multispectral imagery from the Moderate Resolution Imaging Spectroradiometer (MODIS; aboard Earth Observing System Terra and Aqua platforms) and the Sea-viewing Wide Field-of-view Sensor (SeaWiFS; aboard the NASA/Orbimage SeaStar platform). The approach leverages the multi-spectral visible capability of these sensors to distinguish dust from clouds over water bodies, and the high spatial resolution required to refine the fine-scale structures that often accompany these events. The MODIS algorithm combines this information with that of several near-to-far infrared channels, taking advantage of unique spectral properties of dust found in these regimes, to extend the capability to detection of dust over land (bright backgrounds). An account for enhancement contamination in the presence of sun glint is also provided in these products. The SeaWiFS and MODIS telemetries are made available to NRL in near real-time, with product turn-around ranging from 3-6 hours from initial capture. An unprecedented intra-agency collaboration forged between NOAA, NASA (Goddard Space Flight Center), and the Department of Defense has resulted in the recent availability of a global Terra MODIS data stream, with the companion Aqua telemetry soon to follow. Preliminary METOC feedback regarding these products has been overwhelmingly positive, and provides the impetus for continued refinement. Examples of the current product's capabilities and limitations will be presented.

  4. Evaluation of the performance of the MODIS LAI and FPAR algorithm with multiresolution satellite data

    NASA Astrophysics Data System (ADS)

    Tian, Yuhong

    Green leaf area index (LAI) and fraction of photosynthetically active radiation absorbed by vegetation (FPAR) are two key variables of vegetated surfaces because of the important role they play in biosphere-atmosphere interactions. Accurate global estimates of these parameters are essential for understanding and predicting the future state of the climate and terrestrial ecosystems. The objective of this research is to evaluate the performance of a LAI/FPAR algorithm designed for the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard the NASA TERRA spacecraft, with special emphasis on the effects of scale, or spatial resolution. Results from prototyping exercises prior to the launch of MODIS demonstrated the feasibility of physically valid retrievals with the algorithm. It was found that land cover misclassifications between distinct biomes could fatally impact the retrievals. A comparison of coarse (16 km) and fine (30 m) resolution retrievals highlighted the scale dependence of the algorithm. Investigation of the effect of land cover mixtures within coarse resolution pixels shows that LAI retrieval errors are inversely related to the proportion of the dominant land cover in a pixel. Errors are particularly large when forests are minority biomes in non-forest pixels. A physically based theory for scaling with an explicit scale dependent radiative transfer formulation was developed and successfully applied to scale the algorithm to various resolutions of satellite data. Consistency between LAI retrievals from 30 m Landsat Enhanced Thematic Mapper Plus (ETM+) data and field measurements from Maun (Botswana) indicates good performance of the algorithm. LAI values for coarse resolution data are underestimated if the resolution of the data is not considered in the retrieval technique. Hierarchical variance analysis of data from Maun, Harvard Forest (USA) and Ruokulahti Forest (Finland) indicates that LAI estimates derived from ETM+ data exhibit multiple characteristic scales of spatial variation. Isolating the effects associated with different scales through variograms aids the development of a new sampling strategy for validation of MODIS products.

  5. Terrestrial Carbon Sinks in the Brazilian Amazon and Cerrado Region Predicted from MODIS Satellite Data and Ecosystem Modeling

    EPA Science Inventory

    A simulation model based on satellite observations of monthly vegetation cover from the Moderate Resolution Imaging Spectroradiometer (MODIS) was used to estimate monthly carbon fluxes in terrestrial ecosystems of Brazilian Amazon and Cerrado regions over the period 2000-2004. Pr...

  6. Ice cloud backscatter study and comparison with CALIPSO and MODIS satellite data.

    PubMed

    Ding, Jiachen; Yang, Ping; Holz, Robert E; Platnick, Steven; Meyer, Kerry G; Vaughan, Mark A; Hu, Yongxiang; King, Michael D

    2016-01-11

    An invariant imbedding T-matrix (II-TM) method is used to calculate the single-scattering properties of 8-column aggregate ice crystals. The II-TM based backscatter values are compared with those calculated by the improved geometric-optics method (IGOM) to refine the backscattering properties of the ice cloud radiative model used in the MODIS Collection 6 cloud optical property product. The integrated attenuated backscatter-to-cloud optical depth (IAB-ICOD) relation is derived from simulations using a CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite) lidar simulator based on a Monte Carlo radiative transfer model. By comparing the simulation results and co-located CALIPSO and MODIS (Moderate Resolution Imaging Spectroradiometer) observations, the non-uniform zonal distribution of ice clouds over ocean is characterized in terms of a mixture of smooth and rough ice particles. The percentage of the smooth particles is approximately 6% and 9% for tropical and midlatitude ice clouds, respectively. PMID:26832292

  7. Ice Cloud Backscatter Study and Comparison with CALIPSO and MODIS Satellite Data

    NASA Technical Reports Server (NTRS)

    Ding, Jiachen; Yang, Ping; Holz, Robert E.; Platnick, Steven; Meyer, Kerry G.; Vaughan, Mark A.; Hu, Yongxiang; King, Michael D.

    2016-01-01

    An invariant imbedding T-matrix (II-TM) method is used to calculate the single-scattering properties of 8-column aggregate ice crystals. The II-TM based backscatter values are compared with those calculated by the improved geometric-optics method (IGOM) to refine the backscattering properties of the ice cloud radiative model used in the MODIS Collection 6 cloud optical property product. The integrated attenuated backscatter-to-cloud optical depth (IAB-ICOD) relation is derived from simulations using a CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite) lidar simulator based on a Monte Carlo radiative transfer model. By comparing the simulation results and co-located CALIPSO and MODIS (Moderate Resolution Imaging Spectroradiometer) observations, the non-uniform zonal distribution of ice clouds over ocean is characterized in terms of a mixture of smooth and rough ice particles. The percentage of the smooth particles is approximately 6 percent and 9 percent for tropical and mid-latitude ice clouds, respectively.

  8. Intercalibration of Meteorological Satellite Imagers Using VIRS, ATSR-2 and MODIS

    NASA Technical Reports Server (NTRS)

    Nguyen, Louis; Minnis, Patrick; Ayers, J. Kirk; Doelling, David R.

    2001-01-01

    Global retrievals of surface, cloud and radiative properties from geostationary (GEO) and low-Earth-orbit (LEO) meteorological satellites require accurate calibration of their imagers. An accurate and consistent calibration increases the reliability and effectiveness of long-term monitoring of climate changes. More emphasis has been placed on calibrating the thermal infrared (IR) channel. The lack of on-board calibration in the visible (VIS) channel has prompted efforts to characterize the degradation of the VIS sensor using vicarious post-launch calibration techniques that measure bright stable desert targets from space and aircraft or using satellite-to-satellite normalizations. While such inter-calibrations are valuable and widely used, the lack of a well-characterized calibration reference source and the lengthy time delay between updates have minimized their effectiveness in climate monitoring. To address these shortcomings, this paper examines the use of research satellite imagers to provide stable calibration references for the visible (VIS, approximately 0.65 micrometers) channels and develops a method for rapid intercalibration of existing satellites. Calibration coefficients are determined for the Geostationary Operational Environmental Satellites (GOES-8 to GOES-10), Geostationary Meteorological Satellite (GMS-5), Meteosat-7, and the NOAA-14 Advanced Very High Resolution Radiometer (AVHRR). As a reference calibration source, this technique uses the self-calibrating sensors on the Tropical Rainfall Measuring Mission (TRMM) Visible Infrared Radiometers (VIRS) or the ERS-2 Along Track Scanning Radiometer (ATSR-2). GOES-8 is calibrated with VIRS and then its calibration is transferred to other GEO or LEO satellites. The absolute accuracy of this technique relies on the assumption that the on-board calibration is stable and well maintained. Minnis et al. assessed the VIRS calibration using comparisons with other self-calibrated satellite sensors including the broadband Clouds and Earth's Radiant Energy System (CERES) scanners, the ERS-2 Along Track Scanning Radiometer (ATSR-2), and the Terra Moderate-resolution Imaging Spectrometer (MODIS). Thus, the VIRS data can be confidently used as the initial reference source.

  9. Automated dust storm detection using satellite images. Development of a computer system for the detection of dust storms from MODIS satellite images and the creation of a new dust storm database

    NASA Astrophysics Data System (ADS)

    El-Ossta, Esam Elmehde Amar

    Dust storms are one of the natural hazards, which have increased in frequency in the recent years over Sahara desert, Australia, the Arabian Desert, Turkmenistan and northern China, which have worsened during the last decade. Dust storms increase air pollution, impact on urban areas and farms as well as affecting ground and air traffic. They cause damage to human health, reduce the temperature, cause damage to communication facilities, reduce visibility which delays both road and air traffic and impact on both urban and rural areas. Thus, it is important to know the causation, movement and radiation effects of dust storms. The monitoring and forecasting of dust storms is increasing in order to help governments reduce the negative impact of these storms. Satellite remote sensing is the most common method but its use over sandy ground is still limited as the two share similar characteristics. However, satellite remote sensing using true-colour images or estimates of aerosol optical thickness (AOT) and algorithms such as the deep blue algorithm have limitations for identifying dust storms. Many researchers have studied the detection of dust storms during daytime in a number of different regions of the world including China, Australia, America, and North Africa using a variety of satellite data but fewer studies have focused on detecting dust storms at night. The key elements of this present study are to use data from the Moderate Resolution Imaging Spectroradiometers on the Terra and Aqua satellites to develop more effective automated method for detecting dust storms during both day and night and generate a MODIS dust storm database..

  10. Evapotranspiration estimation using Communication, Ocean and Meteorological Satellite (COMS) and MODIS : Comparison and Validation on the Korean Peninsula

    NASA Astrophysics Data System (ADS)

    baek, J.; Choi, M.

    2013-12-01

    Accurate assessment of evapotranspiration (ET) is very important to estimate water balances for understanding of the interaction between the land surface and atmosphere. It is difficult to measure ET with ground-based observation, and limited to indicate on the surface climatological network. To overcome these challenges, spatially distributed ET data with a short time interval and fine spatial resolution is essential for a better estimation of spatio-temporal variability. Existing polar-orbiting satellite such as MODerate-resolution Imaging Spectroradiometer (MODIS) sensor is not capable of continuously observing a certain region. On the contrary, geostationary orbiting satellite has the advantages of continuous measurement of one particular region. Communication, Ocean and Meteorological Satellite (COMS), a geostationary orbiting satellite, were launched in France in 2010. Meteorology Imager (MI) sensor is one of the two sensors boarded on COMS, which observes 15-minute interval data of the atmosphere and Land surface parameters of the earth. In this study, we focused on the comparison of the Actual evapotranspiration (AET) estimated from COMS and MODIS sensor product on the Korean peninsula in 2011. The satellite derived AET was compared with in situ AET measurement from two flux tower sites in the Korean Peninsula. In conclusion, COMS provides better spatio-temporal AET pattern than MODIS and can be applied to a profound understanding of hydrological processes.

  11. Satellite (Timed, Aura, Aqua) and In Situ (Meteorological Rockets, Balloons) Measurement Comparability

    NASA Technical Reports Server (NTRS)

    Schmidlin, F. J.; Goldberg, Richard A.; Feofilov, A.; Rose, R.

    2010-01-01

    Measurements using the inflatable falling sphere often are requested to provide density data in support of special sounding rocket launchings into the mesosphere and thermosphere. To insure density measurements within narrow time frames and close in space, the inflatable falling sphere is launched within minutes of the major test. Sphere measurements are reliable for the most part, however, availability of these rocket systems has become more difficult and, in fact, these instruments no longer are manufactured resulting in a reduction of the meager stockpile of instruments. Sphere measurements also are used to validate remotely measured temperatures and have the advantage of measuring small-scale atmospheric features. Even so, with the dearth of remaining falling spheres perhaps it is time to consider whether the remote measurements are mature enough to stand alone. Presented are two field studies, one in 2003 from Northern Sweden and one in 2010 from the vicinity of Kwajalein Atoll that compare temperature retrievals between satellite and in situ failing spheres. The major satellite instruments employed are SABER, MLS, and AIRS. The comparisons indicate that remotely measured temperatures mimic the sphere temperature measurements quite well. The data also confirm that satellite retrievals, while not always at the exact location required for individual studies, are adaptable enough and highly useful. Although the falling sphere will provide a measurement at a specific location and time, satellites only pass a given location daily or less often. This report reveals that averaged satellite measurements can provide temperatures and densities comparable to the falling sphere.

  12. Satellite (Timed, Aura, Aqua) and In Situ (Meteorological Rockets, Balloons) Measurement Comparability

    NASA Astrophysics Data System (ADS)

    Schmidlin, F. J.; Goldberg, R. A.; Feofilov, A.; Rose, R.

    2010-12-01

    Measurements using the inflatable falling sphere often are requested to provide density data in support of special sounding rocket launchings into the mesosphere and thermosphere. To insure density measurements within narrow time frames and close in space, the inflatable falling sphere is launched within minutes of the major test. Sphere measurements are reliable for the most part, however, availability of these rocket systems has become more difficult and, in fact, these instruments no longer are manufactured resulting in a reduction of the meager stockpile of instruments. Sphere measurements also are used to validate remotely measured temperatures and have the advantage of measuring small-scale atmospheric features. Even so, with the dearth of remaining falling spheres perhaps it is time to consider whether the remote measurements are mature enough to stand alone. Presented are two field studies, one in 2003 from Northern Sweden and one in 2010 from the vicinity of Kwajalein Atoll that compare temperature retrievals between satellite and in situ falling spheres. The major satellite instruments employed are SABER, MLS, and AIRS. The comparisons indicate that remotely measured temperatures mimic the sphere temperature measurements quite well. The data also confirm that satellite retrievals, while not always at the exact location required for individual studies, are adaptable enough and highly useful. Although the falling sphere will provide a measurement at a specific location and time, satellites only pass a given location daily or less often. This report reveals that averaged satellite measurements can provide temperatures and densities comparable to the falling sphere.

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

    NASA Technical Reports Server (NTRS)

    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.

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

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

    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, we evaluated the impact of sensor degradation on trend detection 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, 470nm) degradation on simulated surface reflectance was most pronounced at near-nadir view angles, leading to a 0.001-0.004/yr decline in Normalized Difference Vegetation Index (NDVI) under a range of simulated aerosol conditions and surface types. Observed trends MODIS NDVI over North America were consistent with 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 NDVI trends over vegetation.

  15. A Full Snow Season in Yellowstone: A Database of Restored Aqua Band 6

    NASA Technical Reports Server (NTRS)

    Gladkova, Irina; Grossberg, Michael; Bonev, George; Romanov, Peter; Riggs, George; Hall, Dorothy

    2013-01-01

    The algorithms for estimating snow extent for the Moderate Resolution Imaging Spectroradiometer (MODIS) optimally use the 1.6- m channel which is unavailable for MODIS on Aqua due to detector damage. As a test bed to demonstrate that Aqua band 6 can be restored, we chose the area surrounding Yellowstone and Grand Teton national parks. In such rugged and difficult-to-access terrain, satellite images are particularly important for providing an estimation of snow-cover extent. For the full 2010-2011 snow season covering the Yellowstone region, we have used quantitative image restoration to create a database of restored Aqua band 6. The database includes restored radiances, normalized vegetation index, normalized snow index, thermal data, and band-6-based snow-map products. The restored Aqua-band-6 data have also been regridded and combined with Terra data to produce a snow-cover map that utilizes both Terra and Aqua snow maps. Using this database, we show that the restored Aqua-band-6-based snow-cover extent has a comparable performance with respect to ground stations to the one based on Terra. The result of a restored band 6 from Aqua is that we have an additional band-6 image of the Yellowstone region each day. This image can be used to mitigate cloud occlusion, using the same algorithms used for band 6 on Terra. We show an application of this database of restored band-6 images to illustrate the value of creating a cloud gap filling using the National Aeronautics and Space Administration s operational cloud masks and data from both Aqua and Terra.

  16. Comparison of unfiltered radiances measured by CERES instruments aboard the S-NPP and Terra/Aqua satellites

    NASA Astrophysics Data System (ADS)

    Szewczyk, Z. Peter; Smith, G. Louis; Priestley, Kory J.

    2014-10-01

    The main focus of this paper is a comparison of unfiltered radiances measured by CERES instruments operating on three different platforms, namely the Suomi-NPP, Terra and Aqua satellites. Data for the comparison have been continuously collected since FM5 aboard the S-NPP started its science mission in February of 2012. Three difference strategies have been devised for the purpose of comparing CERES scanners, and two of them utilize a special scanning mode. Since in all three strategies viewing geometries of instruments (FM5 and FM3, and also FM5 and FM1) are matched, comparison at the unfiltered radiance level is enabled. This approach provides a data set with reduced uncertainties for comparing shortwave channels, and also outgoing daytime longwave radiation. Gridded averages are mainly processed to determine differences in scanner's measurements, and statistics are computed primarily for "all-sky" conditions. However, in one of the strategies, comparison is done at a footprint level for a more stringent test of the consistency between the two instruments (FM5 and FM3) for specific scene types. Results of the unfiltered radiance comparison are based on ES8 or ERBE-like data product using Edition-1 for FM5, and Edition-3 for FM1 and FM3.

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

    NASA Technical Reports Server (NTRS)

    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.

  18. MODIS-Derived Nighttime Arctic Land-Surface Temperature Nascent Trends and Non-Stationary Changes

    NASA Astrophysics Data System (ADS)

    Muskett, Reginald

    2014-05-01

    Arctic nighttime Land-Surface Temperatures (LST) derived by the Moderate Resolution Imaging Spectroradiometer (MODIS) sensors onboard the NASA Terra and Aqua satellites are investigated. We use the local equator crossing times of 22:30 and 01:30, respectively, in the analysis of changes, trends and variations on the Arctic region and within 120-degree sectors. We show increases in the number of days above 0C and significant LST increase over decades of March 2000 through 2010 (MODIS Terra) and July 2002 through 2012 (MODIS Aqua). The MODIS Aqua nighttime Arctic LST change, +0.2 +/- 0.2C with P-value of 0.01 indicates a reduction relative to the MODIS Terra nighttime Arctic land-surface temperature change, +1.8 +/- 0.3C with P-value of 0.01. This reduction is a decadal non-stationary component of the Arctic land-surface temperature changes. The reduction is greatest, -1.3 +/- 0.2C with P-value of 0.01 in the Eastern Russia - Western North American sector of the Arctic during the July 2002 through 2012. Ref.: Muskett, R.R., "MODIS-Derived Nighttime Arctic Land-Surface Temperature Nascent Trends and Non-Stationary Changes," American Journal of Climate Change, in press January 2014. http://www.scirp.org/journal/ajcc/

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

    PubMed

    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

  20. Intercomparison of clumping index estimates from POLDER, MODIS, and MISR satellite data over reference sites

    NASA Astrophysics Data System (ADS)

    Pisek, Jan; Govind, Ajit; Arndt, Stefan K.; Hocking, Darren; Wardlaw, Timothy J.; Fang, Hongliang; Matteucci, Giorgio; Longdoz, Bernard

    2015-03-01

    Clumping index is the measure of foliage grouping relative to a random distribution of leaves in space. It is a key structural parameter of plant canopies that influences canopy radiation regimes and controls canopy photosynthesis and other land-atmosphere interactions. The Normalized Difference between Hotspot and Darkspot (NDHD) index has been previously used to retrieve global clumping index maps from POLarization and Directionality of the Earth's Reflectances (POLDER) data at ∼6 km resolution and the Bidirectional Reflectance Distribution Function (BRDF) product from Moderate Resolution Imaging Spectroradiometer (MODIS) at 500 m resolution. Most recently the algorithm was also applied with Multi-angle Imaging SpectroRadiometer (MISR) data at 275 m resolution over selected areas. In this study for the first time we characterized and compared the three products over a set of sites representing diverse biomes and different canopy structures. The products were also directly validated with both in-situ vertical profiles and available seasonal trajectories of clumping index over several sites. We demonstrated that the vertical distribution of foliage and especially the effect of understory need to be taken into account while validating foliage clumping products from remote sensing products with values measured in the field. Satellite measurements responded to the structural effects near the top of canopies, while ground measurements may be biased by the lower vegetation layers. Additionally, caution should be taken regarding the misclassification in land cover maps as their errors can propagate into the foliage clumping maps. Our results indicate that MODIS data and MISR data, with 275 m in particular, can provide good quality clumping index estimates at spatial scales pertinent for modeling local carbon and energy fluxes.

  1. Change in Deep Convective Ice Water Content and Rainrate as Cbserved from AURA MLS, CloudSat, Aqua MODIS, and ISCCP Datasets.

    NASA Astrophysics Data System (ADS)

    Chakraborty, S.; Fu, R.

    2014-12-01

    The influence of aerosols on ice water content (IWC) and rainrate has been suggested by some numerical simulations and observational studies. This is often complicated by a lack of contextual information regarding the dynamic structure and life cycle of the cloud systems. We investigate IWC and rainrate from deep convections (DC) using datasets from AURA Microwave Limb Sounder, CloudSat, Aqua Moderate Resolution Imaging Spectroradiometer, and International Satellite Cloud Climatology Project over the Congo, the Amazon, and South Asia during three different stages of lifecycle. We use measurements from AURA MLS to investigate the change in water content associated with the smaller sized ice crystals at anvil level and CloudSat to derive the relation between the amounts of larger sized ice crystals and rainrate with ambient aerosol loadings. We integrate reflectivity above freezing level (IZ) to calculate the amount of ice and differentiate reflectivity (DZ) with respect to altitude below the freeing level to estimate the attenuated rainfall under the cloud. Our analysis using the reflectivity data shows that IZ and DZ don't change with aerosols loadings during the growing stage. However, IZ increases and DZ decreases, suggesting a delayed precipitation and increase of ice formation, during the matured stage. During the decaying stage, DZ increases, leading to a loss in larger ice particles or as shown by a decrease of the IZ above freezing level. IWC within the anvils of the DCs during their growing stage shows no significant relations with the ambient aerosol concentration over the Congo and South Asia. However, anvil IWC decreases during the matured stage over the South Asia and increase over the Congo as aerosol optical depth surrounding the DCs increases. Aerosol's concentration plays an important role during the decaying stage and is significantly and positively correlated with the IWC of the anvils, suggesting an increase of smaller ice particles in convective anvils with aerosols. Together with the result of CloudSat, our results supports the hypothesis that an increase of aerosols tend to invigorate large mesoscale deep convection by delaying precipitation and increasing both large and smaller ice particles in convective anvils during the mature phase, and increase precipitation during the decay phase.

  2. Global near real-time disturbance monitoring using MODIS satellite image time series

    NASA Astrophysics Data System (ADS)

    Verbesselt, J.; Kalomenopoulos, M.; de Jong, R.; Zeileis, A.; Herold, M.

    2012-12-01

    Global disturbance monitoring in forested ecosystems is critical to retrieve information on carbon storage dynamics, biodiversity, and other socio-ecological processes. Satellite remote sensing provides a means for cost-effective monitoring at frequent time steps over large areas. However, for information about current change processes, it is required to analyse image time series in a fast and accurate manner and to detect abnormal change in near real time. An increasing number of change detection techniques have become available that are able to process historical satellite image time series data to detect changes in the past. However, methods that detect changes near real-time, i.e. analysing newly acquired data with respect to the historical series, are lacking. We propose a statistical technique for monitoring change in near-real time by comparing current data with a seasonal-trend model fitted onto the historical time series. As such, identification of consistent and abnormal change in near-real time becomes possible as soon as new image data is captured. The method is based on the "Break For Additive Seasonal Trend" (BFAST) concept (http://bfast.r-forge.r-project.org/). Disturbances are detected by analysing 16-daily MODIS combined vegetation and temperature indices. Validation is carried out by comparing the detected disturbances with available disturbance data sets (e.g. deforestation in Brazil and MODIS fire products). Preliminary results demonstrated that abrupt changes at the end of time series can be successfully detected while the method remains robust for strong seasonality and atmospheric noise. Cloud masking, however, was identified as a critical issue since periods of persistent cloudiness can be detected as abnormal change. The proposed method is an automatic and robust change detection approach that can be applied on different types of data (e.g. future sensors like the Sentinel constellation that provide higher spatial resolution at regular time steps). The methods for near real-time changes detection are publicly available within the BFAST package for R (http://bfast.r-forge.r-project.org/). Keywords: forest change monitoring, time series imagery, near real-time, change detection

  3. Terra and Aqua satellites track tiger mosquito invasion: modelling the potential distribution of Aedes albopictus in north-eastern Italy

    PubMed Central

    2011-01-01

    Background The continuing spread of the Asian tiger mosquito Aedes albopictus in Europe is of increasing public health concern due to the potential risk of new outbreaks of exotic vector-borne diseases that this species can transmit as competent vector. We predicted the most favorable areas for a short term invasion of Ae. albopictus in north-eastern Italy using reconstructed daily satellite data time series (MODIS Land Surface Temperature maps, LST). We reconstructed more than 11,000 daily MODIS LST maps for the period 2001-09 (i.e. performed spatial and temporal gap-filling) in an Open Source GIS framework. We aggregated these LST maps over time and identified the potential distribution areas of Ae. albopictus by adapting published temperature threshold values using three variables as predictors (0°C for mean January temperatures, 11°C for annual mean temperatures and 1350 growing degree days filtered for areas with autumnal mean temperatures > 11°C). The resulting maps were integrated into the final potential distribution map and this was compared with the known current distribution of Ae. albopictus in north-eastern Italy. Results LST maps show the microclimatic characteristics peculiar to complex terrains, which would not be visible in maps commonly derived from interpolated meteorological station data. The patterns of the three indicator variables partially differ from each other, while winter temperature is the determining limiting factor for the distribution of Ae. albopictus. All three variables show a similar spatial pattern with some local differences, in particular in the northern part of the study area (upper Adige valley). Conclusions Reconstructed daily land surface temperature data from satellites can be used to predict areas of short term invasion of the tiger mosquito with sufficient accuracy (200 m pixel resolution size). Furthermore, they may be applied to other species of arthropod of medical interest for which temperature is a relevant limiting factor. The results indicate that, during the next few years, the tiger mosquito will probably spread toward northern latitudes and higher altitudes in north-eastern Italy, which will considerably expand the range of the current distribution of this species. PMID:21812983

  4. Terrestrial Carbon Fluxes from Deforestation in the Brazilian Amazon and Cerrado Regions Predicted from MODIS Satellite Data and Ecosystem Modeling

    NASA Astrophysics Data System (ADS)

    Klooster, S.; Potter, C.; Genovese, V.

    2008-12-01

    The NASA-CASA (Carnegie Ames Stanford Approach) simulation model based on satellite observations of monthly vegetation cover from the Moderate Resolution Imaging Spectroradiometer (MODIS) was used to estimate tropical forest and savanna (Cerrado) carbon pools for the Brazilian Amazon region over the period 2000-2004. Adjustments for mean age of forest stands were carried out across the region, resulting in a new mapping of aboveground biomass pools based on MODIS satellite data. Yearly maps of newly deforested lands from the Brazilian PRODES (Programa de calculo do desflorestamento da Amazonia ) project were combined with these NASA-CASA biomass predictions to generate seasonal budgets of potential carbon and nitrogen trace gas losses from biomass burning events. Simulations of plant residue and soil carbon decomposition were conducted in the NASA-CASA model during and following deforestation events to track the fate of aboveground biomass pools that were cut and burned each year across the region.

  5. A Project to Map and Monitor Baldcypress Forests in Coastal Louisiana, Using Landsat, MODIS, and ASTER Satellite Data

    NASA Technical Reports Server (NTRS)

    Spruce, Joseph; Sader, Steven; Smoot, James

    2012-01-01

    Cypress swamp forests of Louisiana offer many important ecological and economic benefits: wildlife habitat, forest products, storm buffers, water quality, and recreation. Such forests are also threatened by multiple factors: subsidence, salt water intrusion, sea level rise, persistent flooding, hydrologic modification, hurricanes, insect and nutria damage, timber harvesting, and land use conversion. Unfortunately, there are many information gaps regarding the type, location, extent, and condition of these forests. Better more up to date swamp forest mapping products are needed to aid coastal forest conservation and restoration work (e.g., through the Coastal Forest Conservation Initiative or CFCI). In response, a collaborative project was initiated to develop, test and demonstrate cypress swamp forest mapping products, using NASA supported Landsat, ASTER, and MODIS satellite data. Research Objectives are: Develop, test, and demonstrate use of Landsat and ASTER data for computing new cypress forest classification products and Landsat, ASTER, and MODIS satellite data for detecting and monitoring swamp forest change

  6. Global Aerosol Remote Sensing from MODIS

    NASA Technical Reports Server (NTRS)

    Ichoku, Charles; Kaufman, Yoram J.; Remer, Lorraine A.; Chu, D. Allen; Mattoo, Shana; Tanre, Didier; Levy, Robert; Li, Rong-Rong; Martins, Jose V.; Lau, William K. M. (Technical Monitor)

    2002-01-01

    The physical characteristics, composition, abundance, spatial distribution and dynamics of global aerosols are still very poorly known, and new data from satellite sensors have long been awaited to improve current understanding and to give a boost to the effort in future climate predictions. The derivation of aerosol parameters from the MODerate resolution Imaging Spectro-radiometer (MODIS) sensors aboard the Earth Observing System (EOS) Terra and Aqua polar-orbiting satellites ushers in a new era in aerosol remote sensing from space. Terra and Aqua were launched on December 18, 1999 and May 4, 2002 respectively, with daytime equator crossing times of approximately 10:30 am and 1:30 pm respectively. Several aerosol parameters are retrieved at 10-km spatial resolution (level 2) from MODIS daytime data. The MODIS aerosol algorithm employs different approaches to retrieve parameters over land and ocean surfaces, because of the inherent differences in the solar spectral radiance interaction with these surfaces. The parameters retrieved include: aerosol optical thickness (AOT) at 0.47, 0.55 and 0.66 micron wavelengths over land, and at 0.47, 0.55, 0.66, 0.87, 1.2, 1.6, and 2.1 micron over ocean; Angstrom exponent over land and ocean; and effective radii, and the proportion of AOT contributed by the small mode aerosols over ocean. To ensure the quality of these parameters, a substantial part of the Terra-MODIS aerosol products were validated globally and regionally, based on cross correlation with corresponding parameters derived from ground-based measurements from AERONET (AErosol RObotic NETwork) sun photometers. Similar validation efforts are planned for the Aqua-MODIS aerosol products. The MODIS level 2 aerosol products are operationally aggregated to generate global daily, eight-day (weekly), and monthly products at one-degree spatial resolution (level 3). MODIS aerosol data are used for the detailed study of local, regional, and global aerosol concentration, distribution, and temporal dynamics, as well as for radiative forcing calculations. We show several examples of these results and comparisons with model output.

  7. Aqua Education and Public Outreach

    NASA Astrophysics Data System (ADS)

    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, instrument deployments, instrument sensing, and the Aqua orbit. More recently, in 2008 the Aqua team worked with the ViewSpace production team from the Space Telescope Science Institute to create an 18-minute ViewSpace feature showcasing the science and applications of the Aqua mission. Then in 2010 and 2011, Aqua and other NASA Earth-observing missions partnered with National CineMedia on the "Know Your Earth" (KYE) project. During January and July 2010 and 2011, KYE ran 2-minute segments highlighting questions that promoted global climate literacy on lobby LCD screens in movie theaters throughout the U.S. Among the ongoing Aqua EPO efforts is the incorporation of Aqua data sets onto the Dynamic Planet, a large digital video globe that projects a wide variety of spherical data sets. Aqua also has a highly successful collaboration with EarthSky communications on the production of an Aqua/EarthSky radio show and podcast series. To date, eleven productions have been completed and distributed via the EarthSky network. In addition, a series of eight video podcasts (i.e., vodcasts) are under production by NASA Goddard TV in conjunction with Aqua personnel, highlighting various aspects of the Aqua mission.

  8. Toward Unified Satellite Climatology of Aerosol Properties. 3. MODIS Versus MISR Versus AERONET

    NASA Technical Reports Server (NTRS)

    Mishchenko, Michael I.; Liu, Li; Geogdzhayev, Igor V.; Travis, Larry D.; Cairns, Brian; Lacis, Andrew A.

    2010-01-01

    We use the full duration of collocated pixel-level MODIS-Terra and MISR aerosol optical thickness (AOT) retrievals and level 2 cloud-screened quality-assured AERONET measurements to evaluate the likely individual MODIS and MISR retrieval accuracies globally over oceans and land. We show that the use of quality-assured MODIS AOTs as opposed to the use of all MODIS AOTs has little effect on the resulting accuracy. The MODIS and MISR relative standard deviations (RSTDs) with respect to AERONET are remarkably stable over the entire measurement record and reveal nearly identical overall AOT performances of MODIS and MISR over the entire suite of AERONET sites. This result is used to evaluate the likely pixel-level MODIS and MISR performances on the global basis with respect to the (unknown) actual AOTs. For this purpose, we use only fully compatible MISR and MODIS aerosol pixels. We conclude that the likely RSTDs for this subset of MODIS and MISR AOTs are 73% over land and 30% over oceans. The average RSTDs for the combined [AOT(MODIS)+AOT(MISR)]/2 pixel-level product are close to 66% and 27%, respectively, which allows us to recommend this simple blend as a better alternative to the original MODIS and MISR data. These accuracy estimates still do not represent the totality of MISR and quality-assured MODIS pixel-level AOTs since an unaccounted for and potentially significant source of errors is imperfect cloud screening. Furthermore, many collocated pixels for which one of the datasets reports a retrieval, whereas the other one does not may also be problematic.

  9. Performance of MODIS satellite and mesoscale model based land surface temperature for soil moisture deficit estimation using Neural Network

    NASA Astrophysics Data System (ADS)

    Srivastava, Prashant K.; Petropoulos, George P.; Gupta, Manika; Islam, Tanvir

    2015-04-01

    Soil Moisture Deficit (SMD) is a key variable in the water and energy exchanges that occur at the land-surface/atmosphere interface. Monitoring SMD is an alternate method of irrigation scheduling and represents the use of the suitable quantity of water at the proper time by combining measurements of soil moisture deficit. In past it is found that LST has a strong relation to SMD, which can be estimated by MODIS or numerical weather prediction model such as WRF (Weather Research and Forecasting model). By looking into the importance of SMD, this work focused on the application of Artificial Neural Network (ANN) for evaluating its capabilities towards SMD estimation using the LST data estimated from MODIS and WRF mesoscale model. The benchmark SMD estimated from Probability Distribution Model (PDM) over the Brue catchment, Southwest of England, U.K. is used for all the calibration and validation experiments. The performances between observed and simulated SMD are assessed in terms of the Nash-Sutcliffe Efficiency (NSE), the Root Mean Square Error (RMSE) and the percentage of bias (%Bias). The application of the ANN confirmed a high capability WRF and MODIS LST for prediction of SMD. Performance during the ANN calibration and validation showed a good agreement between benchmark and estimated SMD with MODIS LST information with significantly higher performance than WRF simulated LST. The work presented showed the first comprehensive application of LST from MODIS and WRF mesoscale model for hydrological SMD estimation, particularly for the maritime climate. More studies in this direction are recommended to hydro-meteorological community, so that useful information will be accumulated in the technical literature domain for different geographical locations and climatic conditions. Keyword: WRF, Land Surface Temperature, MODIS satellite, Soil Moisture Deficit, Neural Network

  10. Terrestrial Net Primary Production Predicted from MODIS Satellite Data from 2000-2009

    NASA Astrophysics Data System (ADS)

    Potter, C. S.; Klooster, S. A.; Genovese, V. B.; Gross, P. M.; Hiatt, C.

    2010-12-01

    The CASA (Carnegie-Ames-Stanford) ecosystem model based on satellite greenness observations has been used to estimate monthly carbon fluxes in terrestrial ecosystems from 2000 to 2009. The CASA model was driven by NASA Moderate Resolution Imaging Spectroradiometer (MODIS) vegetation cover properties and large-scale (1-km resolution) disturbance events detected in the monthly time series data. This modeling framework has been implemented to estimate historical as well as current monthly patterns in plant carbon fixation, living biomass increments, and long-term decay of woody (slash) pools before, during, and after land cover disturbance events. For the terrestrial biosphere, predicted net primary production (NPP) flux for atmospheric carbon dioxide has varied notably from year-to-year, but was predicted to have increased overall in the regions of the high-latitude Northern Hemisphere, South Asia, Central Africa, and Western Amazon since the year 2000. Periodic declines in regional NPP levels were predicted for the western Untied States, the southern Amazon, and southern Africa. These CASA NPP results were found to be partially in contrast to other recently published global modeling trends for terrestrial NPP that appear to be highly sensitive to regional drying patterns. Nevertheless, impacts of severe droughts on terrestrial NPP, disturbance frequency, and net ecosystem production sinks for carbon in the CASA model are presently being investigated in greater detail.

  11. Use of MODIS satellite images to investigate the chlorophyll-a concentrations in Lake Okeechobee, Florida

    NASA Astrophysics Data System (ADS)

    Makkeasorn, Ammarin; Cheng, Chi-Han; Chang, Ni-Bin

    2008-08-01

    Lake Okeechobee, Florida is the largest freshwater lake in the southeastern U.S. It is a key component in the hydrologic system of south Florida providing water supply for agriculture, the environment, and urban areas Excessive phosphorus loads, from the Okeechobee watershed over the last few decades have led to increased eutrophication of this. Much of the excess phosphorus has been sequestered into the sediments. Sediment water interactions, including diffusive fluxes and sediment resuspension are a source of available phosphorus for phytoplankton. As a consequence, nutrient-enriched lake water have led to phytoplankton blooms. These blooms are quantified by measurement of chlorophyll-a concentrations. While the in-situ water quality monitoring is time-consuming and costly, multispectral remote sensing sensors onboard satellites can detect chlorophyll-a contained in most phytoplankton efficiently. The objective of this study is to demonstrate the use of MODIS/Terra Surface Reflectance 8-Day images to estimate the chlorophyll-a concentrations in the Lake Okeechobee. Using the integrated genetic programming and multiple linear regression models helps the information retrieval for spatial mapping of chlorophyll-a concentrations.

  12. Aerosol Climatology over Nile Delta based on MODIS, MISR and OMI satellite data

    NASA Astrophysics Data System (ADS)

    Marey, H. S.; Gille, J. C.; El-Askary, H. M.; Shalaby, E. A.; El-Raey, M. E.

    2011-04-01

    Since 1999 Cairo and the Nile delta region have suffered from air pollution episodes called the "black cloud" during the fall season. These have been attributed to either burning of agriculture waste or long-range transport of desert dust. Here we present a detailed analysis of the optical and microphysical aerosol properties, based on satellite data. Monthly mean values of Moderate Resolution Imaging Spectroradiometer (MODIS) aerosol optical depth (AOD) at 550 nm were examined for the 10 yr 2000-2009. Significant monthly variability is observed with maxima in April or May (~0.5) and October (~0.45), and a minimum in December and January (~0.2). Monthly mean values of UV Aerosol Index (UVAI) retrieved by the Ozone Monitoring Instrument (OMI) for 4 yr (2005-2008) exhibit the same AOD pattern. The carbonaceous aerosols during the black cloud periods are confined to the planetary boundary layer (PBL), while dust aerosols exist over a wider range of altitudes, as shown by Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) aerosol profiles. The monthly climatology of Multi-angle Imaging SpectroRadiometer (MISR) data show that the aerosols during the black cloud periods are spherical with a higher percentage of small and medium size particles, whereas the spring aerosols are mostly large non-spherical particles. All of the results show that the air quality in Cairo and the Nile delta region is subject to a complex mixture of air pollution types, especially in the fall season, when biomass burning contributes to a background of urban pollution and desert dust.

  13. Aerosol climatology over Nile Delta based on MODIS, MISR and OMI satellite data

    NASA Astrophysics Data System (ADS)

    Marey, H. S.; Gille, J. C.; El-Askary, H. M.; Shalaby, E. A.; El-Raey, M. E.

    2011-10-01

    Since 1999 Cairo and the Nile delta region have suffered from air pollution episodes called the "black cloud" during the fall season. These have been attributed to either burning of agriculture waste or long-range transport of desert dust. Here we present a detailed analysis of the optical and microphysical aerosol properties, based on satellite data. Monthly mean values of Moderate Resolution Imaging Spectroradiometer (MODIS) aerosol optical depth (AOD) at 550 nm were examined for the 10 yr period from 2000-2009. Significant monthly variability is observed in the AOD with maxima in April or May (~0.5) and October (~0.45), and a minimum in December and January (~0.2). Monthly mean values of UV Aerosol Index (UVAI) retrieved by the Ozone Monitoring Instrument (OMI) for 4 yr (2005-2008) exhibit the same AOD pattern. The carbonaceous aerosols during the black cloud periods are confined to the planetary boundary layer (PBL), while dust aerosols exist over a wider range of altitudes, as shown by Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) aerosol profiles. The monthly climatology of Multi-angle Imaging SpectroRadiometer (MISR) data show that the aerosols during the black cloud periods are spherical with a higher percentage of small and medium size particles, whereas the spring aerosols are mostly large non-spherical particles. All of the results show that the air quality in Cairo and the Nile delta region is subject to a complex mixture of air pollution types, especially in the fall season, when biomass burning contributes to a background of urban pollution and desert dust.

  14. Snow mapping for water resource management using MODIS satellite data in northern Xinjiang, China

    NASA Astrophysics Data System (ADS)

    Pei, Huan; Qin, Zhihao; Fang, Shifeng; Liu, Zhihui

    2008-10-01

    Snow is the most important freshwater resource in northern Xinjiang, which is a typical inland arid ecosystem in western China. Snow mapping can provide useful information for water resource management in this arid ecosystem. An applicable approach for snow mapping in Northern Xinjiang Basin using MODIS data was proposed in this paper. The approach of linear spectral mixture analysis (LSMA) was used to calculate snow cover fractions within a pixel, which was used to establish a regression function with NDSI at a 250-meter grid resolution. Field campaigns were conducted to examine whether NDSI can be used to extend the utility of the snow mapping approach to obtain sub-pixel estimates of snow cover. In addition, snow depths at 80 sampling sites were collected in the study region. The correlation between image reflectivity and snow depth as well as the comparison between measured snow spectra and image spectra were analyzed. An algorithm was developed on the basis of the correlation for snow depth mapping in the region. Validation for another dataset with 50 sampling sites showed an RMSE of 1.63, indicating that the algorithm was able to provide an estimation of snow depth at an accuracy of 1.63cm. The results indicated that snow cover area can reach 81% and average snow depth was 13.8 cm in north Xinjiang in January 2005. Generally speaking, the snow cover and depth had a trend of gradually decreasing from north to south and from the surroundings to the center. Temporally, the cover reached a maximum in early January, and the depth reached a maximum was ten days later. Snow duration was so different in different regions with the Aletai region having the longest and the Bole having the shortest. In the period of snow melting, snow depth decreased earlier, afterward snow cover dwindled. Our study showed that the spatial and temporal variation of snow cover was very critical for water resource management in the arid inland region and MODIS satellite data provide an alternative for snow mapping through dedicated development of mapping algorithms suitable for local application.

  15. Determining Ecosystem Light Use Efficiency from MODIS

    NASA Astrophysics Data System (ADS)

    Huemmrich, K. F.; Middleton, E. M.; Drolet, G.; Hall, F. G.; Knox, R. G.; Margolis, H.

    2006-12-01

    An accurate determination of the spatial and temporal distribution of photosynthetic CO2 uptake is required to understanding the dynamics of the global carbon cycle. Stress factors may result in photosynthetic down- regulation, decreasing ecosystem carbon uptake. Present approaches to determine ecosystem carbon exchange rely on meteorological data as inputs to models that predict the relative photosynthetic function in response to environmental conditions inducing stress (e.g., drought, high/low temperatures). Photosynthetic down-regulation is also related to changes in the apparent spectral reflectance of leaves. This study examines the determination of ecosystem photosynthetic light use efficiency (LUE) from satellite observations, through measurement of vegetation spectral reflectance changes associated with physiologic stress responses. This approach is possible using the Moderate-Resolution Spectroradiometer (MODIS) on Aqua and Terra to provide frequent, narrow-band measurements of high radiometric accuracy. Reflective MODIS ocean bands were used to calculate the Photochemical Reflectance Index (PRI), an index that is sensitive to reflectance changes near 531nm associated with vegetation stress responses exhibited by photosynthetic pigments as well as other reflectance indexes. MODIS PRI values are compared with LUE calculated from half hour values of CO2 flux measured at the overpass time at flux towers at several Fluxnet-Canada network sites. Preliminary results show a good correlation between MODIS PRI and LUE. However, the relationship can be difficult to detect due to differences in viewing geometry of MODIS result in varying fractions of illuminated and shadowed canopy being observed.

  16. Remote Sensing of Agro-droughts in Guangdong Province of China Using MODIS Satellite Data

    PubMed Central

    Gao, Maofang; Qin, Zhihao; Zhang, Hong'ou; Lu, Liping; Zhou, Xia; Yang, Xiuchun

    2008-01-01

    A practical approach was developed in the study for drought monitoring in Guangdong province of China on the basis of vegetation supply water index (VSWI) and precipitation distance index (PDI). A comprehensive index for assessment of agro-drought severity (SADI) was then established from the normalized VSWI and PDI. Using MODIS satellite images and precipitation data from ground-observed meteorological stations, we applied the approach to Guangdong for drought monitoring in 2006. The monitoring results showed that the drought severity on average was very low in the province during the main growing season from May to September in 2006. However, seasonal variation of the severity was also obvious in difference counties of the province. Higher severity of drought could be seen in the periods of late-June (In China each month is traditionally divided into 3 periods. Each is with 10 days and has different names. This division system is mainly with consideration of farming seasons hence has been widely used as the basis of drought monitoring periods in China. In order to keep this tradition, we define, for example, for June, the early-June as the period from 1st to 10th of June, the mid-June as the period from 11th to 20th, and the late-June as the period from 21st to 30th. So mid-August denotes the period from 11th to 20th of August, and early-July the period from 1st to 10th of July, and so on.), early-July, mid-August and late-September. Regionally, Leizhou Peninsula in the west had the most serious drought before mid-May. Validation indicated that our monitoring results were generally consistent with the drought statistics data and the results from Chinese National Satellite Meteorological Center (CNSMC), which used only remote sensing data. This consistence confirmed the applicability of our approach for drought monitoring. Our better identification of drought severity in Leizhou Peninsula of western Guangdong than that of CNSMC might suggest that the approach developed in the study was able to provide a better alternative to increase the accuracy of drought monitoring for agricultural administration and farming.

  17. LSA-SAF evapotranspiration products based on MSG/SEVIRI: improvement opportunities from moderate spatial resolution satellites sensors for vegetation (SPOT-VGT, MODIS, PROBA-V)

    NASA Astrophysics Data System (ADS)

    Ghilain, N.; De Roo, F.; Arboleda, A.; Gellens-Meulenberghs, F.

    2012-04-01

    The Satellite Application Facility on Land Surface Analysis (LSA-SAF) proposes a panel of land surface related products derived from the EUMETSAT satellites, MSG (Meteosat Second Generation) and EPS/METOP, and produced in near-real time over Europe, Africa and part of South America. With LSA-SAF products, key surface variables are observed, and allows to characterizing the main processes governing land atmosphere processes. Land evapotranspiration (ET) is one of the variables monitored within LSA-SAF. ET at a spatial resolution of approximately 3 km at the sub-satellite point above the equator is derived in near-real time, every 30 minutes, using a simplified land surface model, forced by LSA-SAF radiation products derived from MSG/SEVIRI data. Given that spatial resolution, some smaller scale processes cannot be resolved, though their contribution may affect the total MSG pixel area ET estimates. Besides, information with an increased resolution is expected to have a positive impact on the total accuracy of the modeled ET. A variety of new remote sensing products derived from EO data at a higher spatial resolution are now publicly available. This is an opportunity to assess the improvement that moderate spatial resolution (250 m to 1 km) satellites sensors for surface and vegetation characterization could offer to the evapotranspiration monitoring at the MSG/SEVIRI scale in the context of LSA-SAF. On the basis of a global analysis and on test cases, we show the usefulness of EO data acquired from moderate resolution satellites sensors (SPOT-VGT, MODIS/Terra&Aqua, MERIS) towards the improvement of the LSA-SAF ET products derived from MSG/SEVIRI. In particular, 4 different variables/indices (land cover map, LAI, surface albedo, open water bodies detection) are assessed regarding the LSA-SAF ET products: 1) the investigated processes at small scales unresolved by the geostationary satellite, e.g. open water bodies dynamics, are better taken into account in the final ET estimates, 2) an increased spatial resolution of the land cover map used is shown to reduce the uncertainty of evapotranspiration due to geolocation errors, 3) LAI and surface albedo from moderate resolution sensors are shown to give complementary information to MSG derived products in heterogeneous zones. In the present contribution, we briefly describe the LSA-SAF ET products, review the various products derived from moderate resolution satellites sensors that are of interest for the LSA-SAF ET, and assess their respective impact on several test cases. At last, we give a general conclusion about the complementarity of such data to the MSG derived products, also in the perspective of EUMETSAT Meteosat Third Generation satellites and draw some perspectives towards the forthcoming launch of the SPOT-VGT successor, PROBA-V from the enhanced spatial resolution point of view.

  18. In-Depth Evaluation of Aqua MODIS Collection 6 AOD Parameters Over the Contintinental U.S. Via Comparison to Both Ground-Truth and Modeled Data

    NASA Astrophysics Data System (ADS)

    Belle, J. H.; Liu, Y.

    2014-12-01

    We evaluated all four MODIS Collection 6 aerosol AOD parameters: 10 km Dark-Target, 3 km Dark-Target, 10 km Deep-Blue, and 10 km merged Dark-Target and Deep-Blue over the continental U.S. for the years 2011-2013 using AERONET observations. General results of this evaluation are illustrated in the attached figure, which includes data from 84 permanent AERONET sites and 64 DRAGON sites. There are indications of positive retrieval error in the AOD over the continental U.S. for Dark-Target and merged AOD parameters, such that slopes are greater than one, and the percentage of observations above the error envelope (EE, ±(0.05 + 0.15*AERONET AOD) is greater than the percentage below. In contrast, Deep-Blue has a large number of values within the error envelope. However, the correlation with ground observations is poor (r=0.73), the bias is relatively high (0.03) and the slope is below 1 (0.77). While coverage for Deep-Blue retrievals has been improved in Collection 6, the 10 km merged parameter, while partially dependent on Deep-Blue retrievals, performs poorly with regards to coverage, particularly for lower confidence values. For this parameter, an average of only 40.2% of pixels in a valid AERONET-MODIS collocation has any retrieved values. This is in comparison to 72.9% of Deep-Blue pixels and 59.5% of Dark-Target pixels in the same 10 km product. Correlation coefficients between MODIS and AERONET AOD over the Western U.S. are significantly lower (between 0.67 and 0.71) than those in the East, (between 0.84 and 0.93). However, Dark-Target and merged AOD parameters from the West do not show overall positive retrieval errors, and have regression slopes against AERONET observations between 0.98 and 1.02. MODIS aerosol products are further combined with information from the MODIS 16-day gridded NDVI (Normalized Difference Vegetation Index) product, Global Multi-resolution Terrain Elevation Data (GMTED2010), and the National Land Cover Database (NLCD) to elucidate ground conditions which could affect both the accuracy and coverage of AOD retrievals, providing a more nuanced picture of MODIS AOD data over the US. In addition, the spatial pattern of AOD at the national scale is evaluated against simulated AOD by atmospheric chemistry models GOCART and GEOS-Chem.

  19. Annotated Satellite Image of southern Alaska Showing Anchorage and Kodiak Island

    This MODIS Aqua 1-km-resolution, true-color satellite image shows a resuspended ash cloud generated from high winds scouring the dry, unvegetated deposits in the Valley of Ten Thousand Smokes. The cloud stretches across Shelikof Strait to western Kodiak Island. Location: south-central Alaska, from...

  20. Assessment of satellite derived diffuse attenuation coefficients and euphotic depths in south Florida coastal waters

    EPA Science Inventory

    Optical data collected in coastal waters off South Florida and in the Caribbean Sea between January 2009 and December 2010 were used to evaluate products derived with three bio-optical inversion algorithms applied to MOIDS/Aqua, MODIS/Terra, and SeaWiFS satellite observations. Th...

  1. Use of MODIS Satellite Images and an Atmospheric Dust Transport Model to Evaluate Juniperus spp. Pollen Phenology and Transport

    NASA Technical Reports Server (NTRS)

    Luvall, J. C.; Sprigg, W. A.; Levetin, E.; Huete, A.; Nickovic, S.; Pejanovic, G. A.; Vukovic, A.; Van de Water, P. K.; Myers, O. B.; Budge, A. M.; Zelicoff, A. P.; Bunderson, L.; Ponce-Campos, G.; Crimmins, T. M.

    2011-01-01

    Pollen can be transported great distances. Van de Water et al., 2003 reported Juniperus spp. pollen, a significant aeroallergen was transported 200-600 km. Hence local observations of plant phenology may not be consistent with the timing and source of pollen collected by pollen sampling instruments. Direct detection of pollen via satellite is not practical. A practical alternative combines modeling and phenological observations using ground based sampling and satellite data. The DREAM (Dust REgional Atmospheric Model) is a verified model for atmospheric dust transport modeling using MODIS data products to identify source regions and quantities of dust (Nickovic et al. 2001). The use of satellite data products for studying phenology is well documented (White and Nemani 2006). In the current project MODIS data will provide critical input to the PREAM model providing pollen source location, timing of pollen release, and vegetation type. We are modifying the DREAM model (PREAM - Pollen REgional Atmospheric Model) to incorporate pollen transport. The linkages already exist with DREAM through PHAiRS (Public Health Applications in Remote Sensing) to the public health community. This linkage has the potential to fill this data gap so that the potential association of health effects of pollen can better be tracked for possible linkage with health outcome data which may be associated with asthma, respiratory effects, myocardial infarction, and lost workdays. Juniperus spp. pollen phenology may respond to a wide range of environmental factors such as day length, growing degree-days, precipitation patterns and soil moisture. Species differences are also important. These environmental factors vary over both time and spatial scales. Ground based networks such as the USA National Phenology Network have been established to provide national wide observations of vegetation phenology. However, the density of observers is not adequate to sufficiently document the phenology variability over large regions. Hence the use of satellite data is critical to observe Juniperus spp. pollen phenology. MODIS data was used to observe Juniperus spp. pollen phenology. The MODIS surface reflectance product(MOD09) provided information on the Juniper spp. cone formation and cone density (Fig 1). Ground based observational records of pollen release timing and quantities were used as verification. Techniques developed using MOD09 surface reflectance products will be directly applicable to the next generation sensors such as VIIRS.

  2. Use Of MODIS Satellite Images And An Atmospheric Dust Transport Model To Evaluate Juniperus Spp. Pollen Phenology And Transport

    NASA Astrophysics Data System (ADS)

    Luvall, J. C.; Sprigg, W. A.; Levetin, E.; Huete, A. R.; Nickovic, S.; Crimmins, T. M.; Van De Water, P. K.; Pejanovic, G.; Vukovic, A. J.; Myers, O.; Budge, A.; Zelicoff, A.; Bunderson, L.; Ponce-Campos, G.

    2011-12-01

    Pollen can be transported great distances. Van de Water et al., 2003 reported Juniperus spp. pollen, a significant aeroallergen was transported 200-600 km. Hence local observations of plant phenology may not be consistent with the timing and source of pollen collected by pollen sampling instruments. Direct detection of pollen via satellite is not practical. A practical alternative combines modeling and phenological observations using ground based sampling and satellite data. The DREAM (Dust REgional Atmospheric Model) is a verified model for atmospheric dust transport modeling using MODIS data products to identify source regions and quantities of dust (Nickovic et al. 2001). The use of satellite data products for studying phenology is well documented (White and Nemani 2006). In the current project MODIS data will provide critical input to the PREAM model providing pollen source location, timing of pollen release, and vegetation type. We are modifying the DREAM model (PREAM - Pollen REgional Atmospheric Model) to incorporate pollen transport. The linkages already exist with DREAM through PHAiRS (Public Health Applications in Remote Sensing) to the public health community. This linkage has the potential to fill this data gap so that the potential association of health effects of pollen can better be tracked for possible linkage with health outcome data which may be associated with asthma, respiratory effects, myocardial infarction, and lost workdays. Juniperus spp. pollen phenology may respond to a wide range of environmental factors such as day length, growing degree-days, precipitation patterns and soil moisture. Species differences are also important. These environmental factors vary over both time and spatial scales. Ground based networks such as the USA National Phenology Network have been established to provide national wide observations of vegetation phenology. However, the density of observers is not adequate to sufficiently document the phenology variability over large regions. Hence the use of satellite data is critical to observe Juniperus spp. pollen phenology. MODIS data was used to observe Juniperus spp. pollen phenology. The MODIS surface reflectance product(MOD09) provided information on the Juniper spp. cone formation and cone density. Ground based observational records of pollen release timing and quantities were used as verification. Techniques developed using MOD09 surface reflectance products will be directly applicable to the next generation sensors such as VIIRS.

  3. Terrestrial Carbon Sinks in the Brazilian Amazon and Cerrado Region Predicted from MODIS Satellite Data and Ecosystem Modeling

    NASA Technical Reports Server (NTRS)

    Potter, C.; Klooster, S.; Huete, A.; Genovese, V.; Bustamante, M.; Ferreira, L. Guimaraes; deOliveira, R. C., Jr.; Zepp, R.

    2009-01-01

    A simulation model based on satellite observations of monthly vegetation cover from the Moderate Resolution Imaging Spectroradiometer (MODIS) was used to estimate monthly carbon fluxes in terrestrial ecosystems of Brazilian Amazon and Cerrado regions over the period 2000-2004. Net ecosystem production (NEP) flux for atmospheric CO2 in the region for these years was estimated. Consistently high carbon sink fluxes in terrestrial ecosystems on a yearly basis were found in the western portions of the states of Acre and Rondonia and the northern portions of the state of Par a. These areas were not significantly impacted by the 2002-2003 El Nino event in terms of net annual carbon gains. Areas of the region that show periodically high carbon source fluxes from terrestrial ecosystems to the atmosphere on yearly basis were found throughout the state of Maranhao and the southern portions of the state of Amazonas. As demonstrated though tower site comparisons, NEP modeled with monthly MODIS Enhanced Vegetation Index (EVI) inputs closely resembles the measured seasonal carbon fluxes at the LBA Tapajos tower site. Modeling results suggest that the capacity for use of MODIS Enhanced Vegetation Index (EVI) data to predict seasonal uptake rates of CO2 in Amazon forests and Cerrado woodlands is strong.

  4. Terrestrial carbon sinks in the Brazilian Amazon and Cerrado region predicted from MODIS satellite data and ecosystem modeling

    NASA Astrophysics Data System (ADS)

    Potter, C.; Klooster, S.; Huete, A.; Genovese, V.; Bustamante, M.; Guimaraes Ferreira, L.; de Oliveira, R. C., Jr.; Zepp, R.

    2009-06-01

    A simulation model based on satellite observations of monthly vegetation cover from the Moderate Resolution Imaging Spectroradiometer (MODIS) was used to estimate monthly carbon fluxes in terrestrial ecosystems of Brazilian Amazon and Cerrado regions over the period 2000-2004. Net ecosystem production (NEP) flux for atmospheric CO2 in the region for these years was estimated. Consistently high carbon sink fluxes in terrestrial ecosystems on a yearly basis were found in the western portions of the states of Acre and Rondônia and the northern portions of the state of Pará. These areas were not significantly impacted by the 2002-2003 El Niño event in terms of net annual carbon gains. Areas of the region that show periodically high carbon source fluxes from terrestrial ecosystems to the atmosphere on yearly basis were found throughout the state of Maranhão and the southern portions of the state of Amazonas. As demonstrated though tower site comparisons, NEP modeled with monthly MODIS Enhanced Vegetation Index (EVI) inputs closely resembles the measured seasonal carbon fluxes at the LBA Tapajos tower site. Modeling results suggest that the capacity for use of MODIS Enhanced Vegetation Index (EVI) data to predict seasonal uptake rates of CO2 in Amazon forests and Cerrado woodlands is strong.

  5. Terrestrial carbon sinks in the Brazilian Amazon and Cerrado region predicted from MODIS satellite data and ecosystem modeling

    NASA Astrophysics Data System (ADS)

    Potter, C.; Klooster, S.; Huete, A.; Genovese, V.; Bustamante, M.; Guimaraes Ferreira, L.; Cosme de Oliveira Junior, R.; Zepp, R.

    2009-01-01

    A simulation model based on satellite observations of monthly vegetation cover from the Moderate Resolution Imaging Spectroradiometer (MODIS) was used to estimate monthly carbon fluxes in terrestrial ecosystems of Brazilian Amazon and Cerrado regions over the period 2000-2004. Net ecosystem production (NEP) flux for atmospheric CO2 in the region for these years was estimated. Consistently high carbon sink fluxes in terrestrial ecosystems on a yearly basis were found in the western portions of the states of Acre and Rondônia and the northern portions of the state of Pará. These areas were not significantly impacted by the 2002-2003 El Niño event in terms of net annual carbon gains. Areas of the region that show periodically high carbon source fluxes from terrestrial ecosystems to the atmosphere on yearly basis were found throughout the state of Maranhão and the southern portions of the state of Amazonas. As demonstrated though tower site comparisons, NEP modeled with monthly MODIS Enhanced Vegetation Index (EVI) inputs closely resembles the measured seasonal carbon fluxes at the LBA Tapajos tower site. Modeling results suggest that the capacity for use of MODIS Enhanced Vegetation Index (EVI) data to predict seasonal uptake rates of CO2 in Amazon forests and Cerrado woodlands is strong.

  6. Regional-scale carbon flux estimation using MODIS imagery

    NASA Astrophysics Data System (ADS)

    Cordova, Vicente D.

    The National Aeronautics and Space Agency NASA's Moderate Resolution Imaging Spectroradiometer (MODIS) platform carried by Terra and Aqua satellites, is providing systematic measurements summarized in high quality, consistent and well-calibrated satellite images and datasets ranging from reflectance in the visible and near infrared bands to estimates of leaf area index, vegetation indices and biome productivity. The objective of this research was to relate the spectral responses and derived MODIS products of ecosystems, to biogeochemical processes and trends in their physiological variables. When different sources of data were compared, discrepancies between the MODIS variables and the corresponding ground measurements were evident. Uncertainties in the input variables of MODIS products algorithms, effects of cloud cover at the studied pixel, estimation algorithm, and local variation in land cover type are considered as the cause. A simple "continuous field" model based on a physiologically-driven spectral index using two ocean-color bands of MODIS satellite sensor showed great potential to track seasonally changing photosynthetic light use efficiency and stress-induced reduction in net primary productivity of terrestrial vegetation. The model explained 88% of the variability in Flux tower-based daily Net Primary Productivity. Also a high correlation between midday gross CO2 exchange with both daily and 8-day mean gross CO2 exchange, consistent across all the studied vegetation types, was found. Although it may not be possible to estimate 8-day mean Light Use Efficiency reliably from satellite data, Light Use Efficiency models may still be useful for estimation of midday values of gross CO2 exchange which could then be related to longer term means of CO2 exchange. In addition, the MODIS enhanced vegetation index shows a high potential for estimation of ecosystem gross primary production, using respiration values from MODIS surface temperature, providing truly per-pixel estimates.

  7. Application of MODIS-Derived Active Fire Radiative Energy to Fire Disaster and Smoke Pollution Monitoring

    NASA Technical Reports Server (NTRS)

    Ichoku, Charles; Kaufman, Yoram J.; Hao, Wei Min; Habib, Shahid

    2004-01-01

    The radiative energy emitted by large fires and the corresponding smoke aerosol loading are simultaneously measured from the MODIS sensor from both the Terra and Aqua satellites. Quantitative relationships between the rates of emission of fire radiative energy and smoke are being developed for different fire-prone regions of the globe. Preliminary results are presented. When fully developed, the system will enable the use of MODIS direct broadcast fire data for near real-time monitoring of fire strength and smoke emission as well as forecasting of fire progression and smoke dispersion, several hours to a few days in advance.

  8. Analysis of urbanization and climate change impacts on the urban thermal environment based on MODIS satellite data

    NASA Astrophysics Data System (ADS)

    Zoran, Maria A.; Savastru, Roxana S.; Savastru, Dan M.; Tautan, Marina N.; Baschir, Laurentiu A.

    2014-10-01

    Cities are exposed more and more to climate change from greenhouse gas induced radiative forcing, and localized effects from urbanization such as the urban heat island. Urban land covers as the biophysical state of the earth's surface and immediate subsurface are sources and sinks for most of the material and energy movements and interactions between the geosphere and biosphere. Climate change is considered to be the biggest environmental threat in the future in the South- Eastern part of Europe. The aim of this paper is to investigate the influences of urban growth on urban thermal environment as well as the relationships of thermal characteristics to other biophysical parameters in Bucharest metropolitan area of Romania based on time series MODIS Terra/Aqua and IKONOS data acquired during 2000-2014 periods. Land Surface Temperature (LST) is a key variable for studying urban land surface processes and surface atmosphere interactions, being a crucial component in the study of the surface energy and water budgets. Urbanization created an evolved inverse relationship between impervious and vegetation coverage, and brought about new LST patterns because of LST's correlations with both impervious and vegetation coverage. City thermal environment risk management strategies for mitigating and adapting to climate change must propose efficient plans to reduce greenhouse gas (GHG) emissions and cool the city through changes in the built environment, land use, and transportation.

  9. Aerosol Optical Depth investigated with satellite remote sensing observations in China

    NASA Astrophysics Data System (ADS)

    Die, Hu; Lei, Zhang; Hongbin, Wang

    2014-03-01

    In this study, Aerosol Optical Depth (AOD) at 550nm from the MODIS sensor on board the Terra/Aqua satellites were compared with sun photometer (CE-318) measurements from 11 AERONET stations in China. The average correlation coefficient (R) value from the AOD product, using the Aqua-MODIS Deep Blue algorithm, in the Hexi Corridor was 0.67. The MODIS Dark Target algorithm AOD product is superior to Deep Blue algorithm AOD products in SACOL of the Semi-arid regions of the Loess Plateau. These two kinds of algorithm are not applicable to sites in Lanzhou city. The average R value of Dark Target algorithm AOD MODIS products is 0.91 for Terra and 0.88 for Aqua in the eastern part of China. According to the analysis of spatial and temporal characteristics of the two MODIS AOD products in China, high value areas are mainly distributed in the southern part of Xinjiang (0.5~0.8), Sichuan Basin (0.8~0.9), North China (0.6~0.8) and the middle and lower reaches of the Changjiang River (0.8~1.0). The Deep Blue algorithm for Aqua-MODIS is a good supplement for the retrieval of AOD above bright surfaces of deserts in Northwest China.

  10. 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

    NASA Astrophysics Data System (ADS)

    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.

  11. The MODIS Aerosol Algorithm: From First Light to Maturity

    NASA Technical Reports Server (NTRS)

    Remer, L. A.; Levy, R. C.; Kaufman, Y. J.; Holben, B. N.

    2002-01-01

    The MODerate resolution Imaging Spectroradiometer (MODIS) currently aboard both the Terra and Aqua satellites produces a suite of products designed to characterize global aerosol distribution, optical thickness and particle size. Terra with MODIS aboard was launched at the end of 1999 and began transmitting data at the end of February 2000. Algorithms were in place, designed to use the observed radiances to derive many important aerosol products. Early comparisons of the retrieved aerosol parameters with ground-based validation data, showed remarkable agreement between the two types of data, but also showed us situations in which the algorithms could be improved. Almost immediately, the algorithms were modified to reflect a better understanding of the instrument's capabilities and the nature of aerosols and clouds. We describe the MODIS aerosol algorithms, highlighting the changes that were implemented post-launch. We describe the wealth of aerosol products derived from MODIS data and available to any user. Lastly, we compare over a year of MODIS data to co-located ground-based data as validation, and analyze the validation as to geographic location and temporal changes. This presentation is meant as an overview of the mature MODIS aerosol algorithm.

  12. Assessment of MODIS on-orbit spatial performance

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Astrophysics Data System (ADS)

    Redemann, J.; Zhang, Q.; Livingston, J.; Russell, P.; Shinozuka, Y.; Clarke, A.; Johnson, R.; Levy, R.

    2009-11-01

    The 14-channel Ames Airborne Tracking Sunphotometer (AATS) was operated on a Jetstream 31 (J31) aircraft in March 2006 during MILAGRO/INTEX-B (Megacity Initiative-Local And Global Research Observations/Phase B of the Intercontinental Chemical Transport Experiment). We compare AATS retrievals of spectral aerosol optical depth (AOD) and related aerosol properties with corresponding spatially coincident and temporally near-coincident measurements acquired by the MODIS-Aqua and MODIS-Terra satellite sensors. These comparisons are carried out for the older MODIS Collection 4 (C4) and the new Collection 5 (C5) data set, the latter representing a reprocessing of the entire MODIS data set completed during 2006 with updated calibration and aerosol retrieval algorithm. Our analysis yields a direct, validated assessment of the differences between select MODIS C4 and C5 aerosol retrievals. Our analyses of 37 coincident observations by AATS and MODIS-Terra and 18 coincident observations between AATS and MODIS-Aqua indicate notable differences between MODIS C4 and C5 and between the two sensors. For MODIS-Terra, we find an average increase in AOD of 0.02 at 553 nm and 0.01 or less at the shortwave infrared (SWIR) wavelengths. The change from C4 to C5 results in less good agreement with the AATS derived spectral AOD, with average differences at 553 nm increasing from 0.03 to 0.05. For MODIS-Aqua, we find an average increase in AOD of 0.008 at 553 nm, but an increase of nearly 0.02 at the SWIR wavelengths. The change from C4 to C5 results in slightly less good agreement to the AATS derived visible AOD, with average differences at 553 nm increasing from 0.03 to 0.04. However, at SWIR wavelengths, the changes from C4 to C5 result in improved agreement between MODIS-Aqua and AATS, with the average differences at 2119 nm decreasing from -0.02 to -0.003. Comparing the Angstrom exponents calculated from AOD at 553nm and 855nm, we find an increased rms difference from AATS derived Angstrom exponents in going from C4 to C5 for MODIS-Terra, and a decrease in rms difference, hence an improvement, for the transition from C4 to C5 in MODIS-Aqua. Combining the AATS retrievals with in situ measurements of size-dependent aerosol extinction, we derive a suborbital measure of the aerosol submicron fraction (SMF) of AOD and compare it to MODIS retrievals of aerosol fine mode fraction (FMF). Our analysis shows a significant rms-difference between the MODIS-Terra FMF and suborbitally-derived SMF of 0.17 for both C4 and C5. For MODIS-Aqua, there is a slight improvement in the transition from C4 to C5, with the rms-difference from AATS dropping from 0.23 to 0.16. The differences in MODIS C4 and C5 AOD in this limited data set can be traced to changes in the reflectances input to the aerosol retrievals. An extension of the C4-C5 comparisons from the area along the J31 flight track to a larger study region between 18-23° N and 93-100° W on each of the J31 flight days supports the finding of significant differences between MODIS C4 and C5.

  14. MODIS Satellite Data and GOCART Model Characterization of the Global Aerosol

    NASA Technical Reports Server (NTRS)

    Kaufman, Yoram; Chin, Mian; Remer, Lorraine; Tanre, Didier; Lau, William K.-M. (Technical Monitor)

    2003-01-01

    Recently produced daily MODIS aerosol data for the whole year of 2001 are used to show the concentration and dynamics of aerosol over ocean and large parts of the continents. The data were validated against the Aerosol Robotic Network (AERONET) measurements over land and ocean. Monthly averages and a movie based on the daily data are produced and used to demonstrate the spatial and temporal evolution of aerosol. The MODIS wide spectral range is used to distinguish fine smoke and pollution aerosol from coarse dust and salt. The aerosol is observed above ocean and land. The movie produced from the MODIS data provides a new dimension to aerosol observations by showing the dynamics of the system. For example in February smoke and dust emitted from the Sahel and West Africa is shown to travel to the North-East Atlantic. In April heavy dust and pollution from East Asia is shown to travel to North America. In May-June pollution and dust play a dynamical dance in the Arabian Sea and Bay of Bengal. In Aug-September smoke from South Africa and South America is shown to pulsate in tandem and to periodically to be transported to the otherwise pristine Southern part of the Southern Hemisphere. The MODIS data are compared with the GOCART model and used to estimate the first observation based direct anthropogenic radiative forcing of climate by aerosol.

  15. Satellite Monitoring of Asian Dust Storms from SeaWiFS and MODIS: Source, Pathway, and Interannual Variability

    NASA Technical Reports Server (NTRS)

    Hsu, N. Christina; Tsay, S.-C.; Bettenhausen, C.; Salustro, C.; Jeong, M. J.

    2010-01-01

    Among the many components that contribute to air pollution, airborne mineral dust plays an important role due to its biogeochernical impact on the ecosystem and its radiative-forcing effect on the climate system. In East Asia, dust storms frequently accompany the cold and dry air masses that occur as part of springtime cold front systems. China's capital, Beijing, and other large cities are on the primary pathway of these dust storm plumes, and their passage over such population centers causes flight delays, pushes grit through windows and doors, and forces people indoors. Furthermore, during the spring these anthropogenic and natural air pollutants, once generated over the source regions, can be transported out of the boundary layer into the free troposphere and can travel thousands of kilometers across the Pacific into the United States and beyond. In this paper, we will demonstrate the capability of a new satellite algorithm to retrieve aerosol optical thickness and single scattering albedo over bright reflecting surfaces such as urban areas and deserts. Such retrievals have been difficult to perform using previously available algorithms that use wavelengths from the mid-visible to the near IR because they have trouble separating the aerosol signal from the contribution due to the bright surface reflectance. The new algorithm, called Deep Blue, utilizes blue-wavelength measurements from instruments such as SeaWiFS and MODIS to infer the properties of aerosols, since the surface reflectance over land in the blue part of the spectrum is much lower than for longer wavelength channels. We have validated the satellite retrieved aerosol optical thickness with data from AERONET sunphotometers over desert and semi-desert regions. The comparisons show reasonable agreements between these two. These new satellite products will allow scientists to determine quantitatively the aerosol properties near sources using high spatial resolution measurements from SeaWiFS and MODIS-like instruments. The multiyear satellite measurements since 1998 from SeaWiFS will be utilized to investigate the interannual variability of source, pathway, and dust loading associated with these dust outbreaks in East Asia. The monthly averaged aerosol optical thickness during the springtime from SeaWiFS will also be compared with the MODIS Deep Blue products.

  16. Satellite Monitoring of Asian Dust Storms from SeaWiFS and MODIS: Source, pathway and Interannual Variability

    NASA Technical Reports Server (NTRS)

    Hsu, N. Christina

    2007-01-01

    Among the many components that contribute to air pollution, airborne mineral dust plays an important role due to its biogeochemical impact on the ecosystem and its radiative-forcing effect on the climate system. In East Asia, dust storms frequently accompany the cold and dry air masses that occur as part of springtime cold front systems. China's capital, Beijing, and other large cities are on the primary pathway of these dust storm plumes, and their passage over such population centers causes flight delays, pushes grit through windows and doors, and forces people indoors. Furthermore, during the spring these anthropogenic and natural air pollutants, once generated over the source regions, can be transported out of the boundary layer into the free troposphere and can travel thousands of kilometers across the Pacific into the United States and beyond. In this paper, we will demonstrate the capability of a new satellite algorithm to retrieve aerosol optical thickness and single scattering albedo over bright-reflecting surfaces such as urban areas and deserts. Such retrievals have been difficult to perform using previously available algorithms that use wavelengths from the mid-visible to the near IR because they have trouble separating the aerosol signal from the contribution due to the bright surface reflectance. The new algorithm, called Deep Blue, utilizes blue-wavelength measurements from instruments such as SeaWiFS and MODIS to infer the properties of aerosols, since the surface reflectance over land in the blue part of the spectrum is much lower than for longer wavelength channels. We have validated the satellite retrieved aerosol optical thickness with data from AERONET sunphotometers over desert and semi-desert regions. The comparisons show reasonable agreements between these two. These new satellite products will allow scientists to determine quantitatively the aerosol properties near sources using high spatial resolution measurements from SeaWiFS and MODIS-like instruments. The multiyear satellite measurements since 1998 from SeaWiFS will be utilized to investigate the interannual variability of source, pathway, and dust loading associated with these dust outbreaks in East Asia. The monthly averaged aerosol optical thickness during the springtime from SeaWiFS will also be compared with the MODIS Deep Blue products.

  17. Satellite Monitoring of Asian Dust Storms from SeaWiFS and MODIS: Source, Pathway, and Interannual Variability

    NASA Astrophysics Data System (ADS)

    Hsu, N.; Tsay, S.; Jeong, M.; Holben, B.

    2006-12-01

    Among the many components that contribute to air pollution, airborne mineral dust plays an important role due to its biogeochemical impact on the ecosystem and its radiative-forcing effect on the climate system. In East Asia, dust storms frequently accompany the cold and dry air masses that occur as part of spring-time cold front systems. China's capital, Beijing, and other large cities are on the primary pathway of these dust storm plumes, and their passage over such popu-lation centers causes flight delays, pushes grit through windows and doors, and forces people indoors. Furthermore, during the spring these anthropogenic and natural air pollutants, once generated over the source regions, can be transported out of the boundary layer into the free troposphere and can travel thousands of kilometers across the Pacific into the United States and beyond. In this paper, we will demonstrate the capability of a new satellite algorithm to retrieve aerosol optical thickness and single scattering albedo over bright-reflecting surfaces such as urban areas and deserts. Such retrievals have been dif-ficult to perform using previously available algorithms that use wavelengths from the mid-visible to the near IR because they have trouble separating the aerosol signal from the contribution due to the bright surface reflectance. The new algorithm, called Deep Blue, utilizes blue-wavelength measurements from instruments such as SeaWiFS and MODIS to infer the properties of aerosols, since the surface reflectance over land in the blue part of the spectrum is much lower than for longer wavelength channels. We have validated the satellite retrieved aerosol optical thickness with data from AERONET sunphotometers over desert and semi-desert regions. The compari-sons show reasonable agreements between these two. These new satellite prod-ucts will allow scientists to determine quantitatively the aerosol properties near sources using high spatial resolution measurements from SeaWiFS and MODIS-like instruments. The multiyear satellite measurements since 1998 from SeaWiFS will be utilized to investigate the interannual variability of source, pathway, and dust loading associated with these dust outbreaks in East Asia. The monthly av-eraged aerosol optical thickness during the springtime from SeaWiFS will also be compared with the MODIS Deep Blue products.

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

    NASA Astrophysics Data System (ADS)

    Painemal, D.; Minnis, P.; Sun-Mack, S.

    2013-10-01

    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 (<1 μm) for homogeneous scenes (Hσ < 0.2) and LWP > 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.

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

    NASA Technical Reports Server (NTRS)

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

    2008-01-01

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

  20. The MODIS Aerosol Algorithm, Products and Validation

    NASA Technical Reports Server (NTRS)

    Remer, L. A.; Kaufman, Y. J.; Tanre, D.; Mattoo, S.; Chu, D. A.; Martins, J. V.; Li, R.-R.; Ichoku, C.; Levy, R. C.; Kleidman, R. G.

    2003-01-01

    The MODerate resolution Imaging Spectroradiometer (MODIS) aboard both NASA's Terra and Aqua satellites is making near global daily observations of the earth in a wide spectral range. These measurements are used to derive spectral aerosol optical thickness and aerosol size parameters over both land and ocean. The aerosol products available over land include aerosol optical thickness at three visible wavelengths, a measure of the fraction of aerosol optical thickness attributed to the fine mode and several derived parameters including reflected spectral solar flux at top of atmosphere. Over ocean, the aerosol optical thickness is provided in seven wavelengths from 0.47 microns to 2.13 microns. In addition, quantitative aerosol size information includes effective radius of the aerosol and quantitative fraction of optical thickness attributed to the fine mode. Spectral aerosol flux, mass concentration and number of cloud condensation nuclei round out the list of available aerosol products over the ocean. The spectral optical thickness and effective radius of the aerosol over the ocean are validated by comparison with two years of AERONET data gleaned from 133 AERONET stations. 8000 MODIS aerosol retrievals colocated with AERONET measurements confirm that one-standard deviation of MODIS optical thickness retrievals fall within the predicted uncertainty of delta tauapproximately equal to plus or minus 0.03 plus or minus 0.05 tau over ocean and delta tay equal to plus or minus 0.05 plus or minus 0.15 tau over land. 271 MODIS aerosol retrievals co-located with AERONET inversions at island and coastal sites suggest that one-standard deviation of MODIS effective radius retrievals falls within delta r_eff approximately equal to 0.11 microns. The accuracy of the MODIS retrievals suggests that the product can be used to help narrow the uncertainties associated with aerosol radiative forcing of global climate.

  1. Detailed Evaluation of MODIS Fire Radiative Power Measurements

    NASA Technical Reports Server (NTRS)

    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. Introduction to MODIS Cloud Products. Chapter 5

    NASA Technical Reports Server (NTRS)

    Baum, Bryan A.; Platnick, Steven

    2006-01-01

    The Earth's radiative energy balance and hydrological cycle are fundamentally coupled with the distribution and properties of clouds. Therefore, the ability to remotely infer cloud properties and their variation in space and time is crucial for establishing climatologies as a reference for validation of present-day climate models and in assessing future climate change. Remote cloud observations also provide data sets useful for testing and improving cloud model physics, and for assimilation into numerical weather prediction models. The MODerate Resolution Imaging Spectroradiometer (MODIS) imagers on the Terra and Aqua Earth Observing System (EOS) platforms provide the capability for globally retrieving these properties using passive solar reflectance and infrared techniques. In addition to providing measurements similar to those offered on a suite of historical operational weather platforms such as the Advanced Very High Resolution Radiometer (AVHRR), the High-resolution Infrared Radiation Sounder (HIRS), and the Geostationary Operational Environmental Satellite (GOES), MODIS provides additional spectral and/or spatial resolution in key atmospheric bands, along with on-board calibration, to expand the capability for global cloud property retrievals. The core MODIS operational cloud products include cloud top pressure, thermodynamic phase, optical thickness, particle size, and water path, and are derived globally at spatial resolutions of either 1- or 5-km (referred to as Level-2 or pixel-level products). In addition, the MODIS atmosphere team (collectively providing cloud, aerosol, and clear sky products) produces a combined gridded product (referred to as Level-3) aggregated to a 1 equal-angle grid, available for daily, eight-day, and monthly time periods. The wealth of information available from these products provides critical information for climate studies as well as the continuation and improved understanding of existing satellite-based cloud climatologies derived from heritage instruments. This chapter provides an overview of the MODIS Level-2 and -3 operational cloud products.

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

    NASA Astrophysics Data System (ADS)

    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.

  4. Cloud Inhomogeneity from MODIS

    NASA Technical Reports Server (NTRS)

    Oreopoulos, Lazaros; Cahalan, Robert F.

    2004-01-01

    Two full months (July 2003 and January 2004) of MODIS Atmosphere Level-3 data from the Terra and Aqua satellites are analyzed in order to characterize the horizontal variability of cloud optical thickness and water path at global scales. Various options to derive cloud variability parameters are discussed. The climatology of cloud inhomogeneity is built by first calculating daily parameter values at spatial scales of l degree x 1 degree, and then at zonal and global scales, followed by averaging over monthly time scales. Geographical, diurnal, and seasonal changes of inhomogeneity parameters are examined separately for the two cloud phases, and separately over land and ocean. We find that cloud inhomogeneity is weaker in summer than in winter, weaker over land than ocean for liquid clouds, weaker for local morning than local afternoon, about the same for liquid and ice clouds on a global scale, but with wider probability distribution functions (PDFs) and larger latitudinal variations for ice, and relatively insensitive to whether water path or optical thickness products are used. Typical mean values at hemispheric and global scales of the inhomogeneity parameter nu (roughly the mean over the standard deviation of water path or optical thickness), range from approximately 2.5 to 3, while for the inhomogeneity parameter chi (the ratio of the logarithmic to linear mean) from approximately 0.7 to 0.8. Values of chi for zonal averages can occasionally fall below 0.6 and for individual gridpoints below 0.5. Our results demonstrate that MODIS is capable of revealing significant fluctuations in cloud horizontal inhomogenity and stress the need to model their global radiative effect in future studies.

  5. Investigating changes in suspended sediment concentrations in the Peace-Athabasca Delta, Canada using MODIS satellite imagery

    NASA Astrophysics Data System (ADS)

    Long, C.; Pavelsky, T. M.

    2011-12-01

    Changes in the magnitude, distribution, and timing of sedimentary recharge to a freshwater delta have the potential to significantly affect the delta's hydrology, geomorphology, and ecology. The Peace-Athabasca Delta (PAD) in northeastern Alberta, Canada is one system potentially facing significant changes due to substantial decreases in discharge from the Athabasca River into the delta over at least the past four decades. We use bands 1 and 2 of daily 250-m Moderate-Resolution Imaging Spectroradiometer (MODIS) imagery, published river discharge data, and field measurements of suspended sediment concentrations to determine the effects of the decrease in Athabasca River flow on the delivery of sediment throughout the PAD. Daily MODIS images for every summer (May-September) from 2000 to 2011 are used to track the timing, magnitude, and spatial characteristics of the delivery and distribution of high sediment water from the Athabasca River into the delta. Comparison of this time-series of satellite images allows us to examine changes in sedimentary recharge throughout the last decade. Preliminary analysis for 2002 (the lowest water year of the decade) and 2005 (the highest water year) show that in 2005 the amount of sediment delivered to the delta was significantly higher than it was in 2002. This suggests that changes in river discharge do affect the delivery of sediment into the delta. Analysis of MODIS images also reveals that not all areas of the PAD are equally recharged with sediment with any given discharge from the Athabasca River. By comparing the spatial distribution of sediment with same-day discharge on the Athabasca River, we can determine flow thresholds required to deliver sediment to individual lakes. A map of these thresholds allows us to then identify which portions of the PAD are no longer being recharged with sediment under current flow conditions and which additional areas could be particularly vulnerable to further decreases in Athabasca River water levels.

  6. Response to "Toward Unified Satellite Climatology of Aerosol Properties. 3. MODIS Versus MISR Versus AERONET"

    NASA Technical Reports Server (NTRS)

    Kahn, Ralph A.; Garay, Michael J.; Nelson, David L.; Levy, Robert C.; Bull, Michael A.; Diner, David J.; Martonchik, John V.; Hansen, Earl G.; Remer, Lorraine A.; Tanre, Didier

    2010-01-01

    A recent paper by Mishchenko et al. compares near-coincident MISR, MODIS, and AERONET aerosol optical depth (AOD) products, and reports much poorer agreement than that obtained by the instrument teams and others. We trace the reasons for the discrepancies primarily to differences in (1) the treatment of outliers, (2) the application of absolute vs. relative criteria for testing agreement, and (3) the ways in which seasonally varying spatial distributions of coincident retrievals are taken into account.

  7. Inter-annual variations of snow days over Switzerland from 2000-2010 derived from MODIS satellite data

    NASA Astrophysics Data System (ADS)

    Foppa, N.; Seiz, G.

    2012-03-01

    Snow cover plays a vital role in the Swiss Alps and therefore it is of major interest to determine and understand its variability on different spatiotemporal scales. Within the activities of the National Climate Observing System (GCOS Switzerland) inter-annual variations of snow days over Switzerland were derived from 2000 to 2010 based on data from the Moderate Resolution Imaging Spectroradiometer (MODIS) on board the Terra satellite. To minimize the impact of cloud cover on the MODIS snow product MOD10C1, we implemented a post-processing technique based on a forward and backward gap-filling approach. Using the proposed methodology it was possible to determine the total number of annual snow days over Switzerland from 2000 to 2010 (SCDMODIS). The accuracy of the calculated snow days per year were quantitatively evaluated against three in situ snow observation sites representing different climatological regimes (SCDin_situ). Various statistical indices were computed and analysed over the entire period. The overall accuracy between SCDMODIS and SCDin_situ on a daily basis over 10 yr is 88% to 94%, depending on the regional characteristics of each validation site. Differences between SCDMODIS and SCDin_situ vary during the snow accumulation period in autumn and smaller differences after spring, in particularly for the Central Alps.

  8. Investigation and validation of MODIS SST in the northern Persian Gulf

    NASA Astrophysics Data System (ADS)

    Ghanea, Mohsen; Moradi, Masoud; Kabiri, Keivan; Mehdinia, Ali

    2016-01-01

    Validation of satellite derived sea surface temperature (SST) is necessary since satellite minus buoy SST (= bias) relies on atmospheric and oceanographic conditions and time periods. This research validates MODIS (Terra and Aqua) satellite daytime SST with buoy SST at the northern Persian Gulf. Sixteen dates during June 2011 to June 2015 were selected for validation. The buoy-satellite matchups were gained within one image pixel (1 km at nadir) and ±6 h in time. For most matchups, time interval was ±3 h. Effects of total column water vapor, aerosol optical depth, wind speed, glint, and satellite zenith angle on bias are then investigated. These parameters are classified based on root mean square (RMS) difference between satellite and buoy SST. Final results represent a near-perfect R2 (>0.989) for both satellites. The bias was 0.07 ± 0.53 °C and -0.06 ± 0.44 °C for MODIS-Aqua and -Terra, respectively.

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

    NASA Astrophysics Data System (ADS)

    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.

  10. Operationalizing a Research Sensor: MODIS to VIIRS

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

    The National Oceanic and Atmospheric Administration (NOAA) and NASA are jointly acquiring the next-generation civilian environmental satellite system: the Joint Polar Satellite System (JPSS). JPSS will replace the afternoon orbit component and ground processing system of the current Polar-orbiting Operational Environmental Satellites (POES) managed by NOAA. The JPSS satellite will carry a suite of sensors designed to collect meteorological, oceanographic, climatological, and solar-geophysical observations of the earth, atmosphere, and space. The primary sensor for the JPSS mission is the Visible/Infrared Imager Radiometer Suite (VIIRS) developed by Raytheon Space and Airborne Systems (SAS). The ground processing system for the JPSS mission is known as the Common Ground System (JPSS CGS), and consists of a Command, Control, and Communications Segment (C3S) and the Interface Data Processing Segment (IDPS) which are both developed by Raytheon Intelligence and Information Systems (IIS). The Moderate Resolution Imaging Spectroradiometer (MODIS) was developed by Raytheon SAS for the NASA Earth Observing System (EOS) as a research instrument to capture data in 36 spectral bands, ranging in wavelength from 0.4 μm to 14.4 μm and at varying spatial resolutions (2 bands at 250 m, 5 bands at 500 m and 29 bands at 1 km). MODIS data provides unprecedented insight into large-scale Earth system science questions related to cloud and aerosol characteristics, surface emissivity and processes occurring in the oceans, on land, and in the lower atmosphere. MODIS has flown on the EOS Terra satellite since 1999 and on the EOS Aqua satellite since 2002 and provided excellent data for scientific research and operational use for more than a decade. The value of MODIS-derived products for operational environmental monitoring motivated led to the development of an operational counterpart to MODIS for the next-generation polar-orbiting environmental satellites, the Visible/Infrared Imager Radiometer Suite (VIIRS). VIIRS combines the demonstrated high value spectral coverage and radiometric accuracy of MODIS with the legacy spectral bands and radiometric accuracy of the Advanced Very High Resolution Radiometer (AVHRR) and the high spatial resolution (0.75 km) of the Operational Linescan System (OLS). Except for MODIS bands designed for deriving vertical temperature and humidity structure in the atmosphere, VIIRS uses identical or very similar bands from MODIS that have the most interest and usefulness to operational customers in NOAA, the USAF and the USN. The development of VIIRS and JPSS reaps the benefit of investments in MODIS and the NASA EOS and the early development of operational algorithms by NOAA and DoD using MODIS data. This presentation will cover the different aspects of transitioning a research system into an operational system. These aspects include: (1) sensor (hardware & software) operationalization, (2) system performance operational factors, (3) science changes to algorithms reflecting the operational performance factors, and (4) the operationalization and incorporation of the science into a fully 24 x 7 production system, tasked with meeting stringent operational needs. Benefits of early operationalization are discussed along with suggested areas for improvement in this process that could benefit future work such as operationalizing Earth Science Decadal Survey missions.

  11. An Effort to Map and Monitor Baldcypress Forest Areas in Coastal Louisiana, Using Landsat, MODIS, and ASTER Satellite Data

    NASA Technical Reports Server (NTRS)

    Spruce, Joseph P.; Sader, Steve; Smoot, James

    2012-01-01

    This presentation discusses a collaborative project to develop, test, and demonstrate baldcypress forest mapping and monitoring products for aiding forest conservation and restoration in coastal Louisiana. Low lying coastal forests in the region are being negatively impacted by multiple factors, including subsidence, salt water intrusion, sea level rise, persistent flooding, hydrologic modification, annual insect-induced forest defoliation, timber harvesting, and conversion to urban land uses. Coastal baldcypress forests provide invaluable ecological services in terms of wildlife habitat, forest products, storm buffers, and water quality benefits. Before this project, current maps of baldcypress forest concentrations and change did not exist or were out of date. In response, this project was initiated to produce: 1) current maps showing the extent and location of baldcypress dominated forests; and 2) wetland forest change maps showing temporary and persistent disturbance and loss since the early 1970s. Project products are being developed collaboratively with multiple state and federal agencies. Products are being validated using available reference data from aerial, satellite, and field survey data. Results include Landsat TM- based classifications of baldcypress in terms of cover type and percent canopy cover. Landsat MSS data was employed to compute a circa 1972 classification of swamp and bottomland hardwood forest types. Landsat data for 1972-2010 was used to compute wetland forest change products. MODIS-based change products were applied to view and assess insect-induced swamp forest defoliation. MODIS, Landsat, and ASTER satellite data products were used to help assess hurricane and flood impacts to coastal wetland forests in the region.

  12. High Resolution Aerosol Data from MODIS Satellite for Urban Air Quality Studies

    NASA Technical Reports Server (NTRS)

    Chudnovsky, A.; Lyapustin, A.; Wang, Y.; Tang, C.; Schwartz, J.; Koutrakis, P.

    2013-01-01

    The Moderate Resolution Imaging Spectroradiometer (MODIS) provides daily global coverage, but the 10 km resolution of its aerosol optical depth (AOD) product is not suitable for studying spatial variability of aerosols in urban areas. Recently, a new Multi-Angle Implementation of Atmospheric Correction (MAIAC) algorithm was developed for MODIS which provides AOD at 1 km resolution. Using MAIAC data, the relationship between MAIAC AOD and PM(sub 2.5) as measured by the 27 EPA ground monitoring stations was investigated. These results were also compared to conventional MODIS 10 km AOD retrievals (MOD04) for the same days and locations. The coefficients of determination for MOD04 and for MAIAC are R(exp 2) =0.45 and 0.50 respectively, suggested that AOD is a reasonably good proxy for PM(sub 2.5) ground concentrations. Finally, we studied the relationship between PM(sub 2.5) and AOD at the intra-urban scale (10 km) in Boston. The fine resolution results indicated spatial variability in particle concentration at a sub-10 kilometer scale. A local analysis for the Boston area showed that the AOD-PM(sub 2.5) relationship does not depend on relative humidity and air temperatures below approximately 7 C. The correlation improves for temperatures above 7 - 16 C. We found no dependence on the boundary layer height except when the former was in the range 250-500 m. Finally, we apply a mixed effects model approach to MAIAC aerosol optical depth (AOD) retrievals from MODIS to predict PM(sub 2.5) concentrations within the greater Boston area. With this approach we can control for the inherent day-to-day variability in the AOD-PM(sub 2.5) relationship, which depends on time-varying parameters such as particle optical properties, vertical and diurnal concentration profiles and ground surface reflectance. Our results show that the model-predicted PM(sub 2.5) mass concentrations are highly correlated with the actual observations (out-of-sample R(exp 2) of 0.86). Therefore, adjustment for the daily variability in the AOD-PM(sub 2.5) relationship provides a means for obtaining spatially-resolved PM(sub 2.5) concentrations.

  13. Near-Real-Time Detection and Monitoring of Dust Events by Satellite (SeaWIFS, MODIS, and TOMS)

    NASA Technical Reports Server (NTRS)

    Hsu, N. Christina; Tsay, Si-Chee; Herman, Jay R.; Kaufman, Yoram

    2002-01-01

    Over the last few years satellites have given us increasingly detailed information on the size, location, and duration of dust events around the world. These data not only provide valuable feedback to the modelling community as to the fidelity of their aerosol models but are also finding increasing use in near real-time applications. In particular, the ability to locate and track the development of aerosol dust clouds on a near real-time basis is being used by scientists and government to provide warning of air pollution episodes over major urban area. This ability has also become a crucial component of recent coordinated campaigns to study the characteristics of tropospheric aerosols such as dust and their effect on climate. One such recent campaign was ACE-Asia, which was designed to obtain the comprehensive set of ground, aircraft, and satellite data necessary to provide a detailed understanding of atmospheric aerosol particles over the Asian-Pacific region. As part of ACE-Asia, we developed a near real-time data processing and access system to provide satellite data from the polar-orbiting instruments Earth Probe TOMS (in the form of absorbing aerosol index) and SeaWiFS (in the form of aerosol optical thickness, AOT, and Angstrom exponent). The results were available via web access. The location and movement information provided by these data were used both in support of the day-to-day flight planning of ACE-Asia and as input into aerosol transport models. While near real-time SeaWiFS data processing can be performed using either the normal global data product or data obtained via direct broadcast to receiving stations close to the area of interest, near real-time MODIS processing of data to provide aerosol retrievals is currently only available using its direct broadcast capability. In this paper, we will briefly discuss the algorithms used to generate these data. The retrieved aerosol optical thickness and Angstrom exponent from SeaWiFS will be compared with those obtained from various AERONET sites over the Asian-Pacific region. The TOMS aerosol index will also be compared with AERONET aerosol optical thickness over different aerosol conditions, and comparisons between the MODIS and SeaWiFS data will also be presented. Finally, we will discuss the climate implication of our studies using the combined satellite and AERONET observations.

  14. Satellite Monitoring of Asian Dust Storms from SeaWiFS and MODIS: Source, Pathway, and Interannual Variability

    NASA Technical Reports Server (NTRS)

    Hsu, N. Christina; Tsay, S.-C.; Bettenhausen, C.; Sayer, A.

    2011-01-01

    Among the many components that contribute to air pollution, airborne mineral dust plays an important role due to its biogeochemical impact on the ecosystem and its radiative-forcing effect on the climate system. In East Asia, dust storms frequently accompany the cold and dry air masses that occur as part of springtime cold front systems. China's capital, Beijing, and other large cities are on the primary pathway of these dust storm plumes, and their passage over such population centers causes flight delays, pushes grit through windows and doors, and forces peop Ie indoors. Furthermore, during the spring these anthropogenic and natural air pollutants, once generated over the source regions, can be tran sported out of the boundary layer into the free troposphere and can travel thousands of kilometers across the Pacific into the United States and beyond. In this paper, we will demonstrate the capability of a new satellite algorithm to retrieve aerosol optical thickness and single scattering albedo over brightreflecting surfaces such as urban areas and deserts. Such retrievals have been difficult to perform using previously available algorithms that use wavelengths from the mid-visible to the near IR because they have trouble separating the aerosol signal from the contribution due to the bright surface reflectance. The new algorithm, called Deep Blue, utilizes blue-wavelength measurements from instruments such as Sea WiFS and MODIS to infer the properties of aerosols, since the surface reflectance over land in the blue part of the spectrum is much lower than for longer wavelength channels. We have validated the satellite retrieved aerosol optical thickness with data from AERONET sunphotometers over desert and semi-desert regions. The comparisons show reasonable agreements between these two. These new satellite products will allow scientists to determine quantitatively the aerosol properties near sources using high spatial resolution measurements from Sea WiFS and MODISlike instruments. The multiyear satellite measurements since 1998 from SeaWiFS will be utilized to investigate the interannual variability of source, pathway, and dust loading associated with these dust outbreaks in East Asia. The monthly averaged aerosol optical thickness during the springtime from SeaWiFS will also be compared with the MODIS Deep Blue products.

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

    NASA Astrophysics Data System (ADS)

    Redemann, J.; Zhang, Q.; Livingston, J.; Russell, P.; Shinozuka, Y.; Clarke, A.; Johnson, R.; Levy, R.

    2009-05-01

    The 14-channel Ames Airborne Tracking Sunphotometer (AATS) was operated on a Jetstream 31 (J31) aircraft in March 2006 during MILAGRO/INTEX-B (Megacity Initiative-Local And Global Research Observations/Phase B of the Intercontinental Chemical Transport Experiment). We compare AATS retrievals of spectral aerosol optical depth (AOD) and related aerosol properties with corresponding spatially coincident and temporally near-coincident measurements acquired by the MODIS-Aqua and MODIS-Terra satellite sensors. These comparisons are carried out for the older MODIS Collection 4 (C4) and the new Collection 5 (C5) data set, the latter representing a reprocessing of the entire MODIS data set completed during 2006 with updated calibration and aerosol retrieval algorithm. Our analysis yields a direct, validated assessment of the differences between select MODIS C4 and C5 aerosol retrievals. Our analyses of 37 coincident observations by AATS and MODIS-Terra and 18 coincident observations between AATS and MODIS-Aqua indicate notable differences between MODIS C4 and C5 and between the two sensors. For MODIS-Terra, we find an average increase in AOD of 0.02 at 553 nm and 0.01 or less at the shortwave infrared (SWIR) wavelengths. The change from C4 to C5 results in less good agreement with the AATS derived spectral AOD, with average differences at 553 nm increasing from 0.03 to 0.05. For MODIS-Aqua, we find an average increase in AOD of 0.008 at 553 nm, but an increase of nearly 0.02 at the SWIR wavelengths. The change from C4 to C5 results in slightly less good agreement to the AATS derived visible AOD, with average differences at 553 nm increasing from 0.03 to 0.04. However, at SWIR wavelengths, the changes from C4 to C5 result in improved agreement between MODIS-Aqua and AATS, with the average differences at 2119 nm decreasing from -0.02 to -0.003. Comparing the Angstrom exponents calculated from AOD at 553 nm and 855 nm, we find an increased rms difference from AATS derived Angstrom exponents in going from C4 to C5 for MODIS-Terra, and a decrease in rms difference, hence an improvement, for the transition from C4 to C5 in MODIS-Aqua. Combining the AATS retrievals with in situ measurements of size-dependent aerosol extinction, we derive a suborbital measure of the aerosol submicron fraction (SMF) of AOD and compare it to MODIS retrievals of aerosol fine mode fraction (FMF). Our analysis shows a significant rms-difference between the MODIS-Terra FMF and suborbitally-derived SMF of 0.17 for both C4 and C5. For MODIS-Aqua, there is a slight improvement in the transition from C4 to C5, with the rms-difference from AATS dropping from 0.23 to 0.16. The differences in MODIS C4 and C5 AOD in this limited data set can be traced to changes in the reflectances input to the aerosol retrievals. An extension of the C4-C5 comparisons from the area along the J31 flight track to a larger study region between 18-23° N and 93-100° W on each of the J31 flight days supports the finding of significant differences between MODIS C4 and C5.

  16. Discrepancies Between MODIS and ISCCP Land Surface Temperature Products Analyzed with Microwave Measurements

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

    This paper compares land surface temperature (LST) products from the Moderate Resolution Imaging Spectroradiometer (MODIS) and the International Satellite Cloud Climatology Project (ISCCP). With both sources, the LST data are derived from infrared measurements. For ISCCP, LST is a secondary product in support of the primary cloud analyses, but the LST data have been used for several other purposes. The MODIS measurements from the Aqua spacecraft are taken at about 01:30 and 13:30 local time, and the ISCCP three-hourly data, based on several geostationary and polar orbiting satellites. were interpolated to the MODIS measurement times. For July 2003 monthly averages over all clear-sky locations, the ISCCP-MODIS differences were +5.0 K and +2.5 K for day and night, respectively, and there were areas with differences as large as 25 K. The day-night differences were as much as approximately 10 K higher for ISCCP than for MODIS. The MODIS measurements were more consistent with independent microwave measurements from AMSR-E, by several measures, with respect to day-night differences and day-to-day variations.

  17. True Colour Classification of Natural Waters with Medium-Spectral Resolution Satellites: SeaWiFS, MODIS, MERIS and OLCI

    PubMed Central

    van der Woerd, Hendrik J.; Wernand, Marcel R.

    2015-01-01

    The colours from natural waters differ markedly over the globe, depending on the water composition and illumination conditions. The space-borne “ocean colour” instruments are operational instruments designed to retrieve important water-quality indicators, based on the measurement of water leaving radiance in a limited number (5 to 10) of narrow (≈10 nm) bands. Surprisingly, the analysis of the satellite data has not yet paid attention to colour as an integral optical property that can also be retrieved from multispectral satellite data. In this paper we re-introduce colour as a valuable parameter that can be expressed mainly by the hue angle (α). Based on a set of 500 synthetic spectra covering a broad range of natural waters a simple algorithm is developed to derive the hue angle from SeaWiFS, MODIS, MERIS and OLCI data. The algorithm consists of a weighted linear sum of the remote sensing reflectance in all visual bands plus a correction term for the specific band-setting of each instrument. The algorithm is validated by a set of 603 hyperspectral measurements from inland-, coastal- and near-ocean waters. We conclude that the hue angle is a simple objective parameter of natural waters that can be retrieved uniformly for all space-borne ocean colour instruments. PMID:26473859

  18. True colour classification of natural waters with medium-spectral resolution satellites: SeaWiFS, MODIS, MERIS and OLCI.

    PubMed

    Woerd, Hendrik J van der; Wernand, Marcel R

    2015-01-01

    The colours from natural waters differ markedly over the globe, depending on the water composition and illumination conditions. The space-borne "ocean colour" instruments are operational instruments designed to retrieve important water-quality indicators, based on the measurement of water leaving radiance in a limited number (5 to 10) of narrow (≈10 nm) bands. Surprisingly, the analysis of the satellite data has not yet paid attention to colour as an integral optical property that can also be retrieved from multispectral satellite data. In this paper we re-introduce colour as a valuable parameter that can be expressed mainly by the hue angle (α). Based on a set of 500 synthetic spectra covering a broad range of natural waters a simple algorithm is developed to derive the hue angle from SeaWiFS, MODIS, MERIS and OLCI data. The algorithm consists of a weighted linear sum of the remote sensing reflectance in all visual bands plus a correction term for the specific band-setting of each instrument. The algorithm is validated by a set of 603 hyperspectral measurements from inland-, coastal- and near-ocean waters. We conclude that the hue angle is a simple objective parameter of natural waters that can be retrieved uniformly for all space-borne ocean colour instruments. PMID:26473859

  19. Towards Improved MODIS Aerosol Retrieval over the US East Coast Region: Re-examining the Aerosol Model and Surface Assumptions

    NASA Technical Reports Server (NTRS)

    Levy, R. C.; Remer, L. A.; Kaufman, Y. J.; Holben, B. N.

    2002-01-01

    The MODerate resolution Imaging Spectrometer (MODIS) aboard the Terra and recently the Aqua platform, produces a set of aerosol products over both ocean and land regions. Previous validation efforts have shown that from a global perspective, aerosol optical depth (AOD) is successfully retrieved from MODIS. Even over coastal regions, the over- land and over-ocean retrievals are consistent with each other, and well matched with ground-based sunphotometer measurements (such as AERONET). However, the East Coast of the United States is one region where there is consistently a discrepancy between land and ocean retrievals. Over the ocean, MODIS AODs are consistent with coastal sunphotometer measurements, but over land, AODs are consistently over- estimated. In this study we use field data from the Chesapeake Lighthouse and Aircraft Measurements for Satellites experiment (CLAMS), (held during summer 2001) to determine the aerosol properties at a number of sites. Using the 6-S radiative transfer package, we compute simulated satellite radiances and compare them with observed MODIS radiances. We believe that the AOD over-estimation is not likely due to an incorrect choice of the urban/industrial aerosol models. Using 6-S to do an atmospheric correction for a very low AOD case, we show rather, that the discrepancies are likely a result of incorrect assumptions about the surface reflectance properties. Understanding and improving MODIS retrievals over the East Coast will not only improve the global quality of MODIS, but also would enable the use of MODIS as a tool for monitoring regional aerosol events.

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

    NASA Technical Reports Server (NTRS)

    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.

  1. Characterization, validation and intercomparison of clumping index maps from POLDER, MODIS, and MISR satellite data over reference sites

    NASA Astrophysics Data System (ADS)

    Pisek, Jan; He, Liming; Chen, Jing; Govind, Ajit; Sprintsin, Michael; Ryu, Youngryel; Arndt, Stefan; Hocking, Darren; Wardlaw, Timothy; Kuusk, Joel; Oliphant, Andrew; Korhonen, Lauri; Fang, Hongliang; Matteucci, Giorgio; Longdoz, Bernard; Raabe, Kairi

    2015-04-01

    Vegetation foliage clumping significantly alters its radiation environment and therefore affects vegetation growth as well as water and carbon cycles. The clumping index is useful in ecological and meteorological models because it provides new structural information in addition to the effective leaf area index (LAI) retrieved from mono-angle remote sensing and allows accurate separation of sunlit and shaded leaves in the canopy. Not accounting for the foliage clumping in LAI retrieval algorithms leads to substantial underestimation of actual LAI, especially for needleleaf forests. Normalized Difference between Hotspot and Darkspot (NDHD) index has been previously used to retrieve global clumping index maps from POLarization and Directionality of the Earth's Reflectances (POLDER) data at ~6 km resolution, from Moderate Resolution Imaging Spectroradiometer (MODIS) Bidirectional Reflectance Distribution Function (BRDF) product at 500 m resolution. Most recently the algorithm was applied with Multi-angle Imaging SpectroRadiometer (MISR) data at 275 m resolution over selected areas. In this presentation we characterize and intercompare the three products over a set of sites representing diverse biomes and different canopy structures. The products are also directly validated with both in-situ vertical profiles and seasonal trajectories of clumping index. We illustrate that the vertical distribution of foliage and especially the effect of understory needs to be taken into account while validating foliage clumping products from remote sensing products with values measured in the field. Satellite measurements respond to the structural effects near the top of canopies, while ground measurements may be biased by the lower vegetation layers. Additionally, caution should be taken regarding the misclassification in land cover maps as their errors can be propagated into the foliage clumping maps. Our results indicate that MODIS data and MISR data with 275 m in particular can provide good quality clumping index estimates at pertinent scales for modeling local carbon and energy fluxes.

  2. Inter-annual variations of snow days over Switzerland from 2000-2010 derived from MODIS satellite data

    NASA Astrophysics Data System (ADS)

    Foppa, N.; Seiz, G.

    2011-09-01

    Snow cover plays a vital role in the Swiss Alps and therefore it is of major interest to determine and understand its variability on different spatiotemporal scales. Within the activities of the National Climate Observing System (GCOS Switzerland) inter-annual variations of snow days over Switzerland were derived from 2000 to 2010 based on data from the Moderate Resolution Imaging Spectroradiometer (MODIS) on board the Terra satellite. To minimize the impact of cloud cover on the MODIS snow product MOD10C1, we implemented a post-processing technique based on a forward and backward gap-filling approach. Using the proposed methodology it was possible to determine the total number of annual snow days over Switzerland from 2000 to 2010 (SCDMODIS). The accuracy of the calculated snow days per year were quantitatively evaluated against three in situ snow observation sites representing different climatological regimes (SCDin_situ). The correlation (c) between annual SCDMODIS and SCDin_situ is highest for the lowland regions by (c = 0.90) with a slightly lower correlation for the Central Alps of 0.82 and a mean absolute difference of -6 to -7 days (SCDin_situ - SCDMODIS). Differences were further analysed on a monthly and daily resolution over the entire period. The overall agreement between SCDMODIS and SCDin_situ on a daily basis over 10 yr is 88 % to 94 %, depending on the regional characteristics of each validation site. Differences between SCDMODIS and SCDin_situ vary with higher mean absolute differences during the snow accumulation period in autumn and smaller differences after spring, in particularly for the Central Alps. These findings are in agreement with other studies.

  3. Relations of cloud droplet number concentration and aerosol optical depth: An assessment using MODIS satellite observations and the global chemistry climate model EMAC

    NASA Astrophysics Data System (ADS)

    Georgoulias, Aristeidis K.; Karydis, Vlassis A.; Tsimpidi, Alexandra P.; Chang, Dong Yeong; Lelieveld, Jos

    2014-05-01

    In this work, the relation of cloud droplet number concentration (CDNC) and aerosol optical depth (AOD550) as seen from MODIS satellite observations is compared with results from a four-years (2005-2008) simulation with the global chemistry climate model EMAC. This relation is basic to the aerosol first indirect effect on climate and is associated with large uncertainty. It has been shown that MODIS collection 5 data generally exhibit a negative relation over land, which contradicts previous model results. Recent studies attributed this to MODIS difficulties in retrieving CDNC at low cloud fractions. Here, we discuss the differences and similarities of the dln(CDNC)/dln(AOD550) spatiotemporal patterns from MODIS and EMAC. As far as the cloud droplet formation parameterization is considered, EMAC uses the Abdul-Razzak and Ghan (2000) scheme. The main question we address is whether the negative relation appearing over continental regions in MODIS data could be also seen in EMAC simulations for some regions. In these cases, the negative slopes could be attributed to a microphysical effect rather than a retrieval artifact. This work is funded by the QUADIEEMS project, which is co-financed by the European Social Fund (ESF) and national resources under the operational programme Education and Lifelong Learning (EdLL) within the framework of the Action "Supporting Postdoctoral Researchers".

  4. An Overview of MODIS On-orbit Operation, Calibration, and Lessons

    NASA Technical Reports Server (NTRS)

    Xiong, Jack; Barnes, William; Salomonson, Vincent

    2012-01-01

    Two nearly identical copies of the Moderate Resolution Imaging Spectroradiometer (MODIS) have successfully operated onboard the Terra and Aqua spacecraft for more than II years and 9 years since their launch in December 1999 and May 2002, respectively. MODIS is a key instrument for the NASA's Earth Observing System (EOS) missions. MODIS observations have produced an unprecedented amount and a broad range of data products and significantly benefited the science and user community. Its follow-on instrument, the Visible/Infrared Imager Radiometer Suite (VIIRS) on-board the NPOESS Preparatory Project (NPP) spacecraft, is currently scheduled for launch in late October, 2011. The NPP serves as a bridge mission between EOS and the Joint Polar Satellite System (JPSS). MODIS collects data in 36 spectral bands, covering spectral regions from visible (VIS) to long-wave infrared (L WIR), and at three different spatial resolutions. Because of its stringent design requirements, MODIS was built with a complete set of onboard calibrators, including a solar diffuser (SO), a solar diffuser stability monitor (SDSM), a blackbody (BB), a spectroradiometric calibration assembly (SRCA), and a space view (SV) port. Except for tbe SRCA, VIlRS carries the same set of onboard calibrators as MODIS. The SD/SDSM system is used together to calibrate tbe reflective solar bands (RSB). The BB is designed for the thermal emissive bands (TEB) calibration. Similar to Terra and Aqua MODIS, VIlRS will also make regular lunar observations to monitor RSB radiometric calibration stability. In this paper, we provide an overview of MODIS on-orbit operation and calibration activities and present issues identified and lessons learned from mission-long instrument operations and implementation of various calibration and characterization strategies. Examples of both Terra and Aqua MODIS instrument on-orbit performance, including their similarities and unique characteristics, are discussed in tbe context of what might be expected from and benefited to tbe NPP VIlRS operation and calibration. It is anticipated that MODIS experience and lessons will also provide valuable information for other earth observing missions/sensors.

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

    NASA Technical Reports Server (NTRS)

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

    2015-01-01

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

  6. The Aqua-Aura Train

    NASA Technical Reports Server (NTRS)

    Schoeberl, Mark; Einaudi, Franco (Technical Monitor)

    2001-01-01

    This talk will focus on the afternoon constellation of EOS platforms and the scientific benefits that arise from this formation. The afternoon EOS constellation or the "A-train" will provide unprecedented information on clouds and aerosols. At 1:30 PM crossing time EOS-Aqua begins the train with the MODIS, CERES and AIRS instruments making aerosol, cloud, radiation budget , temperature and water vapor measurements. AMSR-E will also make total column water measurements. Following Aqua by one minute, Cloudsat will make active radar precipitation measurements as and PICASSOCENA will make lidar measurements of clouds and aerosols. Fourteen minutes later, EOS-Aura will pass through the same space making upper troposphere water vapor and ice profiles as well as some key trace gases associated with convective processes (MLS and HIRDLS). Additional measurements of aerosols will be made by Aura's OMI instrument.

  7. Comparability of Red/Near-Infrared Reflectance and NDVI Based on the Spectral Response Function between MODIS and 30 Other Satellite Sensors Using Rice Canopy Spectra

    PubMed Central

    Huang, Weijiao; Huang, Jingfeng; Wang, Xiuzhen; Wang, Fumin; Shi, Jingjing

    2013-01-01

    Long-term monitoring of regional and global environment changes often depends on the combined use of multi-source sensor data. The most widely used vegetation index is the normalized difference vegetation index (NDVI), which is a function of the red and near-infrared (NIR) spectral bands. The reflectance and NDVI data sets derived from different satellite sensor systems will not be directly comparable due to different spectral response functions (SRF), which has been recognized as one of the most important sources of uncertainty in the multi-sensor data analysis. This study quantified the influence of SRFs on the red and NIR reflectances and NDVI derived from 31 Earth observation satellite sensors. For this purpose, spectroradiometric measurements were performed for paddy rice grown under varied nitrogen levels and at different growth stages. The rice canopy reflectances were convoluted with the spectral response functions of various satellite instruments to simulate sensor-specific reflectances in the red and NIR channels. NDVI values were then calculated using the simulated red and NIR reflectances. The results showed that as compared to the Terra MODIS, the mean relative percentage difference (RPD) ranged from −12.67% to 36.30% for the red reflectance, −8.52% to −0.23% for the NIR reflectance, and −9.32% to 3.10% for the NDVI. The mean absolute percentage difference (APD) compared to the Terra MODIS ranged from 1.28% to 36.30% for the red reflectance, 0.84% to 8.71% for the NIR reflectance, and 0.59% to 9.32% for the NDVI. The lowest APD between MODIS and the other 30 satellite sensors was observed for Landsat5 TM for the red reflectance, CBERS02B CCD for the NIR reflectance and Landsat4 TM for the NDVI. In addition, the largest APD between MODIS and the other 30 satellite sensors was observed for IKONOS for the red reflectance, AVHRR1 onboard NOAA8 for the NIR reflectance and IKONOS for the NDVI. The results also indicated that AVHRRs onboard NOAA7-17 showed higher differences than did the other sensors with respect to MODIS. A series of optimum models were presented for remote sensing data assimilation between MODIS and other sensors. PMID:24287529

  8. Comparability of red/near-infrared reflectance and NDVI based on the spectral response function between MODIS and 30 other satellite sensors using rice canopy spectra.

    PubMed

    Huang, Weijiao; Huang, Jingfeng; Wang, Xiuzhen; Wang, Fumin; Shi, Jingjing

    2013-01-01

    Long-term monitoring of regional and global environment changes often depends on the combined use of multi-source sensor data. The most widely used vegetation index is the normalized difference vegetation index (NDVI), which is a function of the red and near-infrared (NIR) spectral bands. The reflectance and NDVI data sets derived from different satellite sensor systems will not be directly comparable due to different spectral response functions (SRF), which has been recognized as one of the most important sources of uncertainty in the multi-sensor data analysis. This study quantified the influence of SRFs on the red and NIR reflectances and NDVI derived from 31 Earth observation satellite sensors. For this purpose, spectroradiometric measurements were performed for paddy rice grown under varied nitrogen levels and at different growth stages. The rice canopy reflectances were convoluted with the spectral response functions of various satellite instruments to simulate sensor-specific reflectances in the red and NIR channels. NDVI values were then calculated using the simulated red and NIR reflectances. The results showed that as compared to the Terra MODIS, the mean relative percentage difference (RPD) ranged from -12.67% to 36.30% for the red reflectance, -8.52% to -0.23% for the NIR reflectance, and -9.32% to 3.10% for the NDVI. The mean absolute percentage difference (APD) compared to the Terra MODIS ranged from 1.28% to 36.30% for the red reflectance, 0.84% to 8.71% for the NIR reflectance, and 0.59% to 9.32% for the NDVI. The lowest APD between MODIS and the other 30 satellite sensors was observed for Landsat5 TM for the red reflectance, CBERS02B CCD for the NIR reflectance and Landsat4 TM for the NDVI. In addition, the largest APD between MODIS and the other 30 satellite sensors was observed for IKONOS for the red reflectance, AVHRR1 onboard NOAA8 for the NIR reflectance and IKONOS for the NDVI. The results also indicated that AVHRRs onboard NOAA7-17 showed higher differences than did the other sensors with respect to MODIS. A series of optimum models were presented for remote sensing data assimilation between MODIS and other sensors. PMID:24287529

  9. 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

    NASA Astrophysics Data System (ADS)

    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 the entire region, there is a good agreement between the C051 and C006 AOD retrievals (R=0.917). Nevertheless, the comparison reveals an overestimation/underestimation of C006 with respect to C051 in lower/higher AODs than 0.25. Although the seasonal cycle of AOD does not change from C051 to C006, showing double maxima in boreal spring and summer, positive differences (up to 20%) are found from March to August against negative differences (still up to 20%) in winter and autumn. For α412-470nm, there are negative differences up to 25% throughout the year although both retrievals co-variate in time (R=0.793). The intrannual variation of α412-470nm reveals that the lowest values (~0.5) are found from March to June while the highest ones (0.75-0.83) are observed in winter. According to our results, the seasonal cycles of AOD and Ångström exponent do not reveal significant year by year variation. The study will be complemented in the future by comparing C051 and C006 AOD and α412-470nm MODIS retrievals against corresponding ground measurements from AERONET stations within the study region.

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

    PubMed

    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

  11. Alaska ecosystem carbon fluxes estimated from MODIS satellite data inputs from 2000 to 2010

    PubMed Central

    2013-01-01

    Background Trends in Alaska ecosystem carbon fluxes were predicted from inputs of monthly MODerate resolution Imaging Spectroradiometer (MODIS) vegetation index time-series combined with the NASA-CASA (Carnegie Ames Stanford Approach) carbon cycle simulation model over the past decade. CASA simulates monthly net ecosystem production (NEP) as the difference in carbon fluxes between net primary production (NPP) and soil microbial respiration (Rh). Results Model results showed that NEP on a unit area basis was estimated to be highest (> +10 g C m-2 yr-1) on average over the period 2000 to 2010 within the Major Land Resource Areas (MRLAs) of the Interior Brooks Range Mountains, the Arctic Foothills, and the Western Brooks Range Mountains. The lowest (as negative land C source fluxes) mean NEP fluxes were predicted for the MLRAs of the Cook Inlet Lowlands, the Ahklun Mountains, and Bristol Bay-Northern Alaska Peninsula Lowlands. High levels of interannual variation in NEP were predicted for most MLRAs of Alaska. Conclusions The relatively warm and wet years of 2004 and 2007 resulted in the highest positive NEP flux totals across MLRAs in the northern and western coastal locations in the state (i.e., the Brooks Range Mountains and Arctic Foothills). The relatively cold and dry years of 2001 and 2006 were predicted with the lowest (negative) NEP flux totals for these MLRAs, and likewise across the Ahklun Mountains and the Yukon-Kuskokwim Highlands. PMID:24261829

  12. Actual evapotranspiration estimation in a Mediterranean mountain region by means of Landsat-5 TM and TERRA/AQUA MODIS imagery and Sap Flow measurements in Pinus sylvestris forest stands.

    NASA Astrophysics Data System (ADS)

    Cristóbal, J.; Poyatos, R.; Ninyerola, M.; Pons, X.; Llorens, P.

    2009-04-01

    Evapotranspiration monitoring has important implications on global and regional climate modelling, as well as in the knowledge of the hydrological cycle and in the assessment of environmental stress that affects forest and agricultural ecosystems. An increase of evapotranspiration while precipitation remains constant, or is reduced, could decrease water availability for natural and agricultural systems and human needs. Consequently, water balance methods, as the evapotranspiration modelling, have been widely used to estimate crop and forest water needs, as well as the global change effects. Nowadays, radiometric measurements provided by Remote Sensing and GIS analysis are the technologies used to compute evapotranspiration at regional scales in a feasible way. Currently, the 38% of Catalonia (NE of the Iberian Peninsula) is covered by forests, and one of the most important forest species is Scots Pine (Pinus sylvestris) which represents the 18.4% of the area occupied by forests. The aim of this work is to model actual evapotranspiration in Pinus sylvestris forest stands, in a Mediterranean mountain region, using remote sensing data, and compare it with stand-scale sap flow measurements measured in the Vallcebre research area (42° 12' N, 1° 49' E), in the Eastern Pyrenees. To perform this study a set of 30 cloud-free TERRA-MODIS images and 10 Landsat-5 TM images of path 198 and rows 31 and 32 from June 2003 to January 2005 have been selected to perform evapotranspiration modelling in Pinus sylvestris forest stands. TERRA/AQUA MODIS images have been downloaded by means of the EOS Gateway. We have selected two different types of products which contain the remote sensing data we have used to model daily evapotranspiration, daily LST product and daily calibrated reflectances product. Landsat-5 TM images have been corrected by means of conventional techniques based on first order polynomials taking into account the effect of land surface relief using a Digital Elevation Model, obtaining an RMS less than 30 m. Radiometric correction of Landsat non-thermal bands has been done following the methodology proposed by Pons and Solé (1994) which allows to reduce the number of undesired artifacts that are due to the effects of the atmosphere or to the differential illumination which is, in turn, due to the time of the day, the location in the Earth and the relief (zones being more illuminated than others, shadows, etc). Atmospheric correction of Landsat thermal band has been carried out by means of a single-channel algorithm improvement developed by Cristóbal et al. (2009). To compute actual evapotranspiration (AET) we have used the B-Method proposed by Jakson et al. (1977) and modified by Carlson et al. (1995) and Caselles et al. (1998), based on the energy budget, that needs as an input variables net radiation (Rn) and the difference between land surface temperature (LST) and air temperature (Ta). Air temperature has been modelled by means of multiple regression analysis and GIS interpolation using ground meteorological stations. Net radiation have been computed following two approaches based on the energy balance equation using albedo, land surface temperature, air temperature and solar radiation. Both air temperature and net radiation have been modelled at a regional scale. We have compared remote sensing daily actual evapotranspiration estimates with measured canopy transpiration. Sap flux density was measured by means of Heat dissipation sensors in 12 trees per stand, sampled according to diametric distribution, corrected to account for radial patter of sap flow using the Heat Field Deformation method and then scaled-up to stand level transpiration using tree sapwood areas. Sap flow measurements are comparable with AETd as in the Scots pine stand understorey evaporation is not significant. Measurements with sap flow technique show a mean, minimum and maximum values of AETd = 2.2, 0.6 and 3.6 mm day -1, respectively (Poyatos et al. 2005). Results show, in the case of MODIS AETd modelling, a RMSE of 1.6 mm compared with sap flow measurements. These results show that computing AETd by means of MODIS data in a heterogeneous area do not offer good results due to its spatial resolution (1 km). In the case of Landsat-5 TM AETd modelling, we have obtained better results with a RMSE of 0.6 mm which are in agreement with other studies that present an estimated error of about ± 30%. Moreover, we have to take into account that Landsat-like spatial resolution seems to be the best option to estimate AETd in this kind of areas. Keywords: Actual evapotranspiration modelling, Sap Flow, Remote Sensing, Pinus sylvestris, Mediterranian region.

  13. Earth Observing System (EOS) Aqua Launch and Early Mission Attitude Support Experiences

    NASA Technical Reports Server (NTRS)

    Tracewell, D.; Glickman, J.; Hashmall, J.; Natanson, G.; Sedlak, J.

    2003-01-01

    The Earth Observing System (EOS) Aqua satellite was successfully launched on May 4,2002. Aqua is the second in the series of EOS satellites. EOS is part of NASA s Earth Science Enterprise Program, whose goals are to advance the scientific understanding of the Earth system. Aqua is a three-axis stabilized, Earth-pointing spacecraft in a nearly circular, sun-synchronous orbit at an altitude of 705 km. The Goddard Space Flight Center (GSFC) Flight Dynamics attitude team supported all phases of the launch and early mission. This paper presents the main results and lessons learned during this period, including: real-time attitude mode transition support, sensor calibration, onboard computer attitude validation, response to spacecraft emergencies, postlaunch attitude analyses, and anomaly resolution. In particular, Flight Dynamics support proved to be invaluable for successful Earth acquisition, fine-point mode transition, and recognition and correction of several anomalies, including support for the resolution of problems observed with the MODIS instrument.

  14. Production and Distribution of NASA MODIS Remote Sensing Products

    NASA Technical Reports Server (NTRS)

    Wolfe, Robert

    2007-01-01

    The two Moderate Resolution Imaging Spectroradiometer (MODIS) instruments on-board NASA's Earth Observing System (EOS) Terra and Aqua satellites make key measurements for understanding the Earth's terrestrial ecosystems. Global time-series of terrestrial geophysical parameters have been produced from MODIS/Terra for over 7 years and for MODIS/Aqua for more than 4 1/2 years. These well calibrated instruments, a team of scientists and a large data production, archive and distribution systems have allowed for the development of a new suite of high quality product variables at spatial resolutions as fine as 250m in support of global change research and natural resource applications. This talk describes the MODIS Science team's products, with a focus on the terrestrial (land) products, the data processing approach and the process for monitoring and improving the product quality. The original MODIS science team was formed in 1989. The team's primary role is the development and implementation of the geophysical algorithms. In addition, the team provided feedback on the design and pre-launch testing of the instrument and helped guide the development of the data processing system. The key challenges the science team dealt with before launch were the development of algorithms for a new instrument and provide guidance of the large and complex multi-discipline processing system. Land, Ocean and Atmosphere discipline teams drove the processing system requirements, particularly in the area of the processing loads and volumes needed to daily produce geophysical maps of the Earth at resolutions as fine as 250 m. The processing system had to handle a large number of data products, large data volumes and processing loads, and complex processing requirements. Prior to MODIS, daily global maps from heritage instruments, such as Advanced Very High Resolution Radiometer (AVHRR), were not produced at resolutions finer than 5 km. The processing solution evolved into a combination of processing the lower level (Level 1) products and the higher level discipline specific Land and Atmosphere products in the MODIS Science Investigator Lead Processing System (SIPS), the MODIS Adaptive Processing System (MODAPS), and archive and distribution of the Land products to the user community by two of NASA s EOS Distributed Active Archive Centers (DAACs). Recently, a part of MODAPS, the Level 1 and Atmosphere Archive and Distribution System (LAADS), took over the role of archiving and distributing the Level 1 and Atmosphere products to the user community.

  15. Construction of lake bathymetry from MODIS satellite data and GIS from 2003 to 2011

    NASA Astrophysics Data System (ADS)

    Yan, Yi; Xiao, Fei; Du, Yun

    2014-05-01

    In recent years, sedimentation conditions in Dongting Lake have varied greatly because of signifi cant changes in runoff and sediment load in the Changjiang (Yangtze) River following the construction of Three Gorges Dam. The topography of the lake bottom has changed rapidly because of the intense exchange of water and sediment between the lake and the Changjiang River. However, time series information on lake-bottom topographic change is lacking. In this study, we introduced a method that combines remote sensing data and in situ water level data to extract a record of Dongting Lake bottom topography from 2003 to 2011. Multi-temporal lake land/water boundaries were extracted from MODIS images using the linear spectral mixture model method. The elevation of water/land boundary points were calculated using water level data and spatial interpolation techniques. Digital elevation models of Dongting Lake bottom topography in different periods were then constructed with the multiple heighted waterlines. The mean root-mean-square error of the linear spectral mixture model was 0.036, and the mean predicted error for elevation interpolation was -0.19 m. Compared with fi eld measurement data and sediment load data, the method has proven to be most applicable. The results show that the topography of the bottom of Dongting Lake has exhibited uneven erosion and deposition in terms of time and space over the last nine years. Moreover, lake-bottom topography has undergone a slight erosion trend within this period, with 58.2% and 41.8% of the lake-bottom area being eroded and deposited, respectively.

  16. Analysis of agricultural drought using vegetation temperature condition index (VTCI) from Terra/MODIS satellite data.

    PubMed

    Patel, N R; Parida, B R; Venus, V; Saha, S K; Dadhwal, V K

    2012-12-01

    The most commonly used normalized difference vegetation index (NDVI) from remote sensing often fall short in real-time drought monitoring due to a lagged vegetation response to drought. Therefore, research recently emphasized on the use of combination of surface temperature and NDVI which provides vegetation and moisture conditions simultaneously. Since drought stress effects on agriculture are closely linked to actual evapotranspiration, we used a vegetation temperature condition index (VTCI) which is more closely related to crop water status and holds a key place in real-time drought monitoring and assessment. In this study, NDVI and land surface temperature (T (s)) from MODIS 8-day composite data during cloud-free period (September-October) were adopted to construct an NDVI-T (s) space, from which the VTCI was computed. The crop moisture index (based on estimates of potential evapotranspiration and soil moisture depletion) was calculated to represent soil moisture stress on weekly basis for 20 weather monitoring stations. Correlation and regression analysis were attempted to relate VTCI with crop moisture status and crop performance. VTCI was found to accurately access the degree and spatial extent of drought stress in all years (2000, 2002, and 2004). The temporal variation of VTCI also provides drought pattern changes over space and time. Results showed significant and positive relations between CMI (crop moisture index) and VTCI observed particularly during prominent drought periods which proved VTCI as an ideal index to monitor terminal drought at regional scale. VTCI had significant positive relationship with yield but weakly related to crop anomalies. Duration of terminal drought stress derived from VTCI has a significant negative relationship with yields of major grain and oilseeds crops, particularly, groundnut. PMID:22200944

  17. Use of MODIS Satellite Data to Evaluate Juniperus spp. Pollen Phenology to Support a Pollen Dispersal Model, PREAM, to Support Public Health Allergy Alerts

    NASA Technical Reports Server (NTRS)

    Luvall, J. C.; Sprigg, W.; Levetin, E.; Huete, A.; Nickovic, S.; Pejanovic, G. A.; Vukovic, A.; VandeWater, P.; Budge, A.; Hudspeth, W.; Krapfl, H.; Toth, B.; Zelicoff, A.; Myers, O.; Bunderson, L.; Ponce-Campos, G.; Crimmins, T.; Menache, M.

    2012-01-01

    Juniperus spp. pollen is a significant aeroallergen that can be transported 200-600 km from the source. Local observations of Juniperus spp. phenology may not be consistent with the timing and source of pollen collected by pollen sampling instruments. Methods: The Dust REgional Atmospheric Model (DREAM)is a verified model for atmospheric dust transport modeling using MODIS data products to identify source regions and quantities of dust. We successfully modified the DREAM model to incorporate pollen transport (PREAM) and used MODIS satellite images to develop Juniperus ashei pollen input source masks. The Pollen Release Potential Source Map, also referred to as a source mask in model applications, may use different satellite platforms and sensors and a variety of data sets other than the USGS GAP data we used to map J. ashei cover type. MODIS derived percent tree cover is obtained from MODIS Vegetation Continuous Fields (VCF) product (collection 3 and 4, MOD44B, 500 and 250 m grid resolution). We use updated 2010 values to calculate pollen concentration at source (J. ashei ). The original MODIS derived values are converted from native approx. 250 m to 990m (approx. 1 km) for the calculation of a mask to fit the model (PREAM) resolution. Results: The simulation period is chosen following the information that in the last 2 weeks of December 2010. The PREAM modeled near-surface concentrations (Nm-3) shows the transport patterns of J. ashei pollen over a 5 day period (Fig. 2). Typical scales of the simulated transport process are regional.

  18. The generation of the Potential Fishing Zone (PFZ) information using MODIS satellites based on chlorophyll and sea surface temperature.

    NASA Astrophysics Data System (ADS)

    Tijani, Khalid; Morea, Alberto; Chiaradia, Maria Teresa; Pasquariello, Guido; Nutricato, Raffaele

    2014-05-01

    Relevant oceanographic conditions, such as sea surface temperature (SST), chlorophyll concentration (CHL) and oceanic fronts, which strongly influence natural fluctuations of fish stocks, can be observed and measured by remote sensors on satellites and aircraft. The high spatiotemporal frequency of MODIS data (twice per day, 500m resolution) are provided in near-real time to help fishermen save fuel and ship time during their search for fish located along the Adriatic Sea. The purpose of this work is the integration of CHL and SST to generate potential fishing zones (PFZs) using an gradient-based edge detection algorithm [1]. The position of the fronts is detected by a Canny filter [2] were applied to gradient of CHL and SST images; the potential edges were subsequently validated statistically [3] and then were compared in terms of categorized fish catch per unit effort (CPUE, total catch divided by actual fishing hours). The results of this study will be presented and commented. References [1] Oram, John J., James C. McWilliams, and Keith D. Stolzenbach. "Gradient-based edge detection and feature classification of sea-surface images of the Southern California Bight." Remote Sensing of Environment 112.5 (2008): 2397-2415. [2] Canny, John. "A computational approach to edge detection." Pattern Analysis and Machine Intelligence, IEEE Transactions on 6 (1986): 679-698. [3] CAYULA, JEAN-F., and Peter Cornillon. "Edge detection algorithm for SST images." Journal of Atmospheric and Oceanic Technology 9.1 (1992): 67-80.

  19. MODIS Validation, Data Merger and Other Activities Accomplished by the SIMBIOS Project: 2002-2003

    NASA Technical Reports Server (NTRS)

    Fargion, Giulietta S.; McClain, Charles R.

    2003-01-01

    The purpose of this technical report is to provide current documentation of the Sensor Intercomparison and Merger for Biological and Interdisciplinary Oceanic Studies (SIMBIOS) Project activities, satellite data processing, and data product validation. This documentation is necessary to ensure that critical information is related to the scientific community and NASA management. This critical information includes the technical difficulties and challenges of validating and combining ocean color data from an array of independent satellite systems to form consistent and accurate global bio-optical time series products. This technical report focuses on the SIMBIOS Project s efforts in support of the Moderate-Resolution Imaging Spectroradiometer (MODIS) on the Earth Observing System (EOS) Terra platform (similar evaluations of MODIS/Aqua are underway). This technical report is not meant as a substitute for scientific literature. Instead, it will provide a ready and responsive vehicle for the multitude of technical reports issued by an operational project.

  20. Early-season crop area estimates for winter crops in NE Australia using MODIS satellite imagery

    NASA Astrophysics Data System (ADS)

    Potgieter, A. B.; Apan, A.; Hammer, G.; Dunn, P.

    To date, industry and crop forecasters have had a good idea of the potential crop yield for a specific season, but early-season information on crop area for a shire or region has been mostly unavailable. The question of "how early and with what accuracy?" area estimates can be determined using multi-temporal Moderate Resolution Imaging Spectroradiometer (MODIS) enhanced vegetation index (EVI) imagery was investigated in this paper. The study was conducted for two shires in Queensland, Australia for the 2003 and 2004 seasons, and focused on deriving total winter crop area estimates (including wheat, barley and chickpea). A simple metric ( ΔE), which measures the green-up rate of the crop canopy, was derived. Using the unsupervised k-means classification algorithm, the accumulated difference of two consecutive images (one month apart) for three EVI threshold cut-offs ( ΔEi, where i=250, 500 and 750) at monthly intervals from April to October was calculated. July showed the highest pixel accuracy with percent correctly classified for all thresholds of 94% and 98% for 2003 and 2004, respectively. The differences in accuracy between the three cut-offs were minimal and the T500 threshold was selected as the preferred cut-off to avoid measuring too small or too large fluctuations in the differential EVI values. When compared to the aggregated shire data (surveyed) on crop area across shires and seasons, average percent differences for the ΔE for July and August ranged from -19% to 9%. To capture most of the variability in green-up within a region, the average ΔE of July and August was used for the early-season prediction of total winter crop area estimates. This resulted in high accuracy (R 2=0.96; RMSE = 3157 ha) for predicting the total winter crop from 2000 to 2004 across both shires. This result indicated that this simple multi-temporal remote sensing approach could be used with confidence in early-season crop area prediction at least one to two months ahead of anthesis.

  1. Atmospheric Correction of High-Spatial-Resolution Commercial Satellite Imagery Products Using MODIS Atmospheric Products

    NASA Technical Reports Server (NTRS)

    Pagnutti, Mary; Holekamp, Kara; Ryan, Robert E.; Vaughan, Ronald; Russell, Jeffrey A.; Prados, Don; Stanley, Thomas

    2005-01-01

    Remotely sensed ground reflectance is the basis for many inter-sensor interoperability or change detection techniques. Satellite inter-comparisons and accurate vegetation indices such as the Normalized Difference Vegetation Index, which is used to describe or to imply a wide variety of biophysical parameters and is defined in terms of near-infrared and redband reflectance, require the generation of accurate reflectance maps. This generation relies upon the removal of solar illumination, satellite geometry, and atmospheric effects and is generally referred to as atmospheric correction. Atmospheric correction of remotely sensed imagery to ground reflectance, however, has been widely applied to only a few systems. In this study, we atmospherically corrected commercially available, high spatial resolution IKONOS and QuickBird imagery using several methods to determine the accuracy of the resulting reflectance maps. We used extensive ground measurement datasets for nine IKONOS and QuickBird scenes acquired over a two-year period to establish reflectance map accuracies. A correction approach using atmospheric products derived from Moderate Resolution Imaging Spectrometer data created excellent reflectance maps and demonstrated a reliable, effective method for reflectance map generation.

  2. Remote Sensing of Cloud, Aerosol, and Land Properties from MODIS: Applications to the East Asia Region

    NASA Technical Reports Server (NTRS)

    King, Michael D.; Platnick, Steven; Moody, Eric G.

    2002-01-01

    MODIS is an earth-viewing cross-track scanning spectroradiometer launched on the Terra satellite in December 1999 and the Aqua satellite in May 2002. MODIS scans 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, and provides images in 36 spectral bands between 0.415 and 14.235 microns with spatial resolutions 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 atmospheric processes. In this paper we will describe the various methods being used for the remote sensing of cloud, aerosol, and surface properties using MODIS data, focusing primarily on (i) the MODIS cloud mask used to distinguish clouds, clear sky, heavy aerosol, and shadows on the ground, (ii) cloud optical properties, especially cloud optical thickness and effective radius of water drops and ice crystals, (iii) aerosol optical thickness and size characteristics both over land and ocean, and (iv) ecosystem classification and surface spectral reflectance. The physical principles behind the determination of each of these products will be described, together with an example of their application using MODIS observations to the east Asian region. All products are archived into two categories: pixel-level retrievals (referred to as Level-2 products) and global gridded products at a latitude and longitude resolution of 1 min (Level-3 products).

  3. Monitoring the spatial and temporal dynamics of annual floods in the Niger Inner Delta using MODIS satellite imagery

    NASA Astrophysics Data System (ADS)

    Ogilvie, A.; Belaud, G.; Delenne, C.; Bader, J.-C.; Oleksiak, A.; Bailly, J.-S.

    2012-04-01

    The Niger Inner Delta is a vast three million hectare wetland in Mali, whose annual flood supports the livelihoods of over one million herders, fishermen and farmers. Large projects on the Niger River upstream may however alter the extent and dynamics of the flood in the future. Due to the scale (about 50 000 km2) and the very flat topography of this hydrological system, there is very scarce ground data to characterise the flood and its spatial and temporal dynamics remain poorly understood. Since the flood is mainly caused by precipitation in the upper catchment, the flood peak in the delta occurs a few weeks after the rainy season, when cloud cover does not limit the use of optical remote sensing data. An original automated method was developed to study the progress of the flooding using normalised band ratio indices on 8-day MODIS (Moderate Resolution Imaging Spectroradiometer) 500m-satellite images. The Modified Normalised Difference Water Index (MNDWI) was shown to be the most suitable for detecting flooded areas out of six commonly used band ratio indices. Its combination with the Normalised Difference Moisture Index (NDMI) aids the distinction between flooded and humid vegetation, especially in the drier months when the flood recedes. Three 30m Landsat images covering different phases of the flood, on which K-means clustering and analysis of spectral profiles enabled the identification of flooded pixels, were used to calibrate the threshold values of both indices. A programme using a specific composite MNDWI-NDMI index, with constant thresholds and a topographically relevant grid of the river and its floodplain was developed in ENVI IDL© to automatically provide the percentage of flooded pixels per grid cell for each image. The method was validated by computing correlations between water depth measurements from gauging stations in the delta and the flooded surface area for the corresponding grid cell calculated from the MODIS images. Estimates of the total surface area flooded are also coherent with previous values found in the literature. MODIS images provide adequate spatial resolution and sufficient temporal resolution to monitor the flood from September through to February. The beginning of the flood in August could not be monitored, due to the presence of clouds. This method was developed on images from the period 2001-2010. It provides a dynamic assessment of the total area flooded, as well as information on the timing and duration of the flood per area. This knowledge may assist farmers and stakeholders in planning their agricultural activities, notably flood recession cropping. Its results may also be used to develop and calibrate a hydraulic model of the flooding of the Inner Delta, as well as a finer estimate of the water balance of the area, notably evapotranspiration values and contributions to downstream flows. Residual uncertainties, due to difficulties in distinguishing between flooded and humid vegetation especially as the flood recedes, could be reduced with additional ground truth data.

  4. Near Real-time Derived Products from MODIS

    NASA Technical Reports Server (NTRS)

    Suggs, Ron; Jedlovec, Gary; Haines, Stephanie

    2004-01-01

    As part of the Short-term Prediction Research Transition (SPoRT) program at NASA/MSFC, near real-time total precipitable water and land/sea surface temperature products from MODIS, on NASA's Terra and Aqua satellites, are being derived from a subset of MODIS channels with spectral characteristics similar to those planned for the GOES-R ABI. Under the SPoRT program these products are made available to several NWS Forecast Offices to assist in the preparation of short-term forecasts. This transition activity, from research to operations, serves to prepare forecasters for the next generation of satellite observing capabilities through real-time, hands-on applications to their forecast problems. The derived products are produced from a physical retrieval algorithm which can be applied to polar or geostationary measurements. The algorithm is a perturbation solution of the radiation transfer equation for a nonscattering atmosphere requiring first-guess temperature and moisture profiles. For this application first-guess information is obtained from the latest model forecasts. The utility of this retrieval approach is that it provides a near real-time high resolution update of a model's forecasted parameter allowing forecasters to validate and monitor the performance of the model's forecast. The poster will provide a description of the retrieval methodology and examples of the derived products. Case studies will also be presented comparing these products with those obtained from the Earth Observing System (EOS) MODIS science team algorithms.

  5. A comparative study of lossless compression algorithms on MODIS data

    NASA Astrophysics Data System (ADS)

    Gottipati, Srikanth; Goddard, Jamal; Grossberg, Michael; Gladkova, Irina

    2007-09-01

    This paper reports a comparative study of lossless compression algorithms for MODIS data. MODIS, The Moderate Resolution Imaging Spectroradiometer, is a 36 band Visible and IR multispectral imager aboard the Terra and Aqua satellites, having spatial resolution ranging from 0.250 to 1 kilometer and spectral resolution ranging from 0.405 -0.420 to 4.482-4.549 microns. MODIS data rates are 10.6 Mbps (peak daytime); and 6.1 Mbps (orbital average). Faced with such an enormous volume of data on a current generation imager, this study provides a comparison of current compression algorithms as a baseline for future work. The Hierarchical Data Format (HDF) is standard format selected for data archiving and distribution within the Earth Observing System Data and Information System (EOSDIS). Currently this system handles over one terabyte of data daily, and this volume continues to increase over time. With growing satellite Earth science multispectral imager volume data compression, it becomes increasingly important to evaluate which compression algorithms are most appropriate for data management in transmission and archiving. This comparative compression study uses a wide range standard implementations of the leading lossless compression algorithms. Examples include image compression algorithms such as PNG and JPEG2000, and widely-used file compression formats such as BZIP2 and 7z. This study includes a comparison with the Consultative Committee for Space Data Systems (CCSDS) most recent recommended compression standard. by a significant margin.

  6. Using MODIS data to estimate river discharge in ungauged sites

    NASA Astrophysics Data System (ADS)

    Tarpanelli, A.; Brocca, L.; Lacava, T.; Faruolo, M.; Melone, F.; Moramarco, T.; Pergola, N.; Tramutoli, V.

    2012-04-01

    The discharge prediction at a river site is fundamental for water resources management and flood risk prevention. An accurate discharge estimation depends on local hydraulic conditions which are usually detected by recording water level and carrying out flow measurements, which are costly and sometimes impractical for high flows. Over the last decade, the possibility to obtain river discharge estimates from satellite sensors data has become of considerable interest. For large river basins, the use of satellite data derived by altimeter and microwave sensors, characterized by a daily temporal resolution, has proven to be a useful tool to integrate or even increase the discharge monitoring. For smaller basins, Synthetic Aperture Radars (SARs) have been usually employed for the indirect estimation of water elevation but their low temporal resolution (from a few days up to 30 days) might be considered not suitable for discharge prediction. The Moderate Resolution Imaging Spectroradiometer (MODIS) aboard of Terra and Aqua Earth Observing System (EOS) satellites, can provide a proper tradeoff between temporal and spatial resolution useful for discharge estimation. It assures, in fact, at least a daily temporal resolution and a spatial resolution up to 250 m in the first two channels. In this study, the capability of MODIS data for discharge prediction is investigated. Specifically, the different spectral behavior of water and land in the Near Infrared (NIR) portion of the electromagnetic spectrum (MODIS channel 2) is exploited by computing the ratio of the MODIS channel 2 reflectance values between two pixels located within and outside the river. Values of such a ratio should increase when more water and, hence, discharge, is present. Time series of daily water level, velocity and discharge between 2002 and 2010 measured at different gauging stations located along the Upper Tiber River (central Italy) and the Po River (North Italy), as well as MODIS channel 2 data for the same period are employed to testing the procedure. The agreement between MODIS-derived and in situ discharge time series is found to be fairly good with maximum correlation coefficient values equal to ~0.8. The empirical relationships between satellite and in-situ time-series are investigated in-depth to regionalize their parameters and, hence, to estimate the discharge also for ungauged river sites based on MODIS data.

  7. The MODIS Aerosol Algorithm, Products, Validation and Applications

    NASA Technical Reports Server (NTRS)

    Remer, L. A.; Kaufman, Y. J.; Tanre, D.

    2003-01-01

    The MODerate resolution Imaging Spectroradiometer (MODIS) currently aboard both the Terra and Aqua satellites produces a suite of products designed to characterize global aerosol distribution, optical thickness and particle size. Never before has a space-borne instrument been able to provide such detailed information, complementing field and modeling efforts to produce a comprehensive picture of aerosol characteristics. The three years of Terra-MODIS data have been validated by comparing with co-located AERONET observations of aerosol optical thickness and derivations of aerosol size parameters. Some 8000 comparison points located at 133 AERONET sites around the globe show that the MODIS aerosol optical thickness retrievals are accurate to within the pre-launch expectations. MODIS-derived size parameters are also compared with AERONET retrievals and found to agree well for fine-mode dominated aerosol regimes. Aerosol regimes dominated by dust aerosol are less accurate, attributed to what is thought to be nonsphericity. Errors due to nonsphericity will be reduced by introducing a new set of empirical phase functions, derived without any assumptions of particle shape. The major innovation that MODIS bring to the field of remote sensing of aerosol is the measure of particle size and the separation of finemode and coarsemode dominated aerosol regimes. Particle size can separate finemode man-made aerosols created during combustion, from larger natural aerosols originating from salt spray or wind erosion. This separation allows for the calculation of aerosol radiative effect and the estimation of the man-made aerosol radiative forcing. MODIS can also be used in regional studies of aerosol-cloud interaction that affect the global radiative and hydrological cycles.

  8. Improving the accuracy of MODIS 8-day snow products with in situ temperature and precipitation data

    NASA Astrophysics Data System (ADS)

    Dong, Chunyu; Menzel, Lucas

    2016-03-01

    MODIS snow data are appropriate for a wide range of eco-hydrological studies and applications in the fields of snow-related hazards, early warning systems and water resources management. However, the high spatio-temporal resolution of the remotely sensed data is often biased by snow misclassifications, and cloud cover frequently limits the availability of the MODIS-based snow cover information. In this study, we applied a four-step methodology that aims to optimize the accuracy of MODIS snow data. To reduce the cloud fraction, 8-day MODIS data from both the Aqua and Terra satellites were combined. Neighborhood analysis was applied as well for this purpose, and it also contributed to the retrieval of some omitted snow. Two meteorological filters were then applied to combine information from station-based measurements of minimum ground temperature, precipitation and air temperature. This procedure helped to reduce the overestimation of snow cover. To test this technique, the methodology was applied to the Rhineland-Palatinate region in southwestern Germany (approximately 20,000 km2), where cloud cover is especially high during winter and surface heterogeneity is complex. The results show that mean annual cloud coverage (reference period 2002-2013) of the 8-day MODIS snow maps could be reduced using this methodology from approximately 14% to 4.5%. During the snow season, obstruction by clouds could be reduced by even a higher degree, but still remains at about 11%. Further, the overall snow overestimation declined from 11.0-11.9% (using the original Aqua-Terra data) to 1.0-1.5%. The method is able to improve the overall accuracy of the 8-day MODIS snow product from originally 78% to 89% and even to 93% during cloud free periods.

  9. Multilayered Clouds Identification and Retrieval for CERES Using MODIS

    NASA Technical Reports Server (NTRS)

    Sun-Mack, Sunny; Minnis, Patrick; Chen, Yan; Yi, Yuhong; Huang, Jainping; Lin, Bin; Fan, Alice; Gibson, Sharon; Chang, Fu-Lung

    2006-01-01

    Traditionally, analyses of satellite data have been limited to interpreting the radiances in terms of single layer clouds. Generally, this results in significant errors in the retrieved properties for multilayered cloud systems. Two techniques for detecting overlapped clouds and retrieving the cloud properties using satellite data are explored to help address the need for better quantification of cloud vertical structure. The first technique was developed using multispectral imager data with secondary imager products (infrared brightness temperature differences, BTD). The other method uses microwave (MWR) data. The use of BTD, the 11-12 micrometer brightness temperature difference, in conjunction with tau, the retrieved visible optical depth, was suggested by Kawamoto et al. (2001) and used by Pavlonis et al. (2004) as a means to detect multilayered clouds. Combining visible (VIS; 0.65 micrometer) and infrared (IR) retrievals of cloud properties with microwave (MW) retrievals of cloud water temperature Tw and liquid water path LWP retrieved from satellite microwave imagers appears to be a fruitful approach for detecting and retrieving overlapped clouds (Lin et al., 1998, Ho et al., 2003, Huang et al., 2005). The BTD method is limited to optically thin cirrus over low clouds, while the MWR method is limited to ocean areas only. With the availability of VIS and IR data from the Moderate Resolution Imaging Spectroradiometer (MODIS) and MW data from the Advanced Microwave Scanning Radiometer EOS (AMSR-E), both on Aqua, it is now possible to examine both approaches simultaneously. This paper explores the use of the BTD method as applied to MODIS and AMSR-E data taken from the Aqua satellite over non-polar ocean surfaces.

  10. Daily estimates of fire danger using multitemporal satellite MODIS data: the experience of FIRE-SAT in the Basilicata Region (Italy)

    NASA Astrophysics Data System (ADS)

    Lanorte, R.; Lasaponara, R.; De Santis, F.; Aromando, A.; Nole, G.

    2012-04-01

    Daily estimates of fire danger using multitemporal satellite MODIS data: the experience of FIRE-SAT in the Basilicata Region (Italy) A. Lanorte, F. De Santis , A. Aromando, G. Nolè, R. Lasaponara, CNR-IMAA, Potenza, Italy In the recent years the Basilicata Region (Southern Italy) has been characterized by an increasing incidence of fire disturbance which also tends to affect protected (Regional and national parks) and natural vegetated areas. FIRE_SAT project has been funded by the Civil Protection of the Basilicata Region in order to set up a low cost methodology for fire danger/risk monitoring based on satellite Earth Observation techniques. To this aim, NASA Moderate Resolution Imaging Spectroradiometer (MODIS) data were used. The spectral capability and daily availability makes MODIS products especially suitable for estimating the variations of fuel characteristics. This work presents new significant results obtained in the context of FIRE-SAT project. In order to obtain a dynamical indicator of fire susceptibility based on multitemporal MODIS satellite data, up-datable in short-time periods (daily), we used the spatial/temporal variations of following parameters: (1) Relative Greenness Index (2) Live and dead fuel moisture content (3) Temperature In particular, the dead fuel moisture content is a key factor in fire ignition. Dead fuel moisture dynamics are significantly faster than those observed for live fuel. Dead fine vegetation exhibits moisture and density values dependent on rapid atmospheric changes and strictly linked to local meteorological conditions. For this reason, commonly, the estimation of dead fuel moisture content is based on meteorological variables. In this study we propose to use MODIS data to estimate meteorological data (specifically Relative Humidity) at an adequate spatial and temporal resolution. The assessment of dead fuel moisture content plays a decisive role in determining a fire dynamic danger index in combination with other factors. This greatly improves the reliability of fire danger maps obtained on the basis of a integrated approach of the dynamic factors mentioned above and the static factors (fuel physical properties, morphological parameters and social-historical factors). The validation of the fire danger indices was carried out by the use of statistics of occurred forest fires. The validation results show satisfactory agreement with the fire danger map taking into account that . fire events are indirect indicator of fire danger; indeed, many factor influence fire ignition and spread such as human pressure, fire-fighting conditions, wind, etc.. Therefore, in this study we have defined and used several fire statistic data useful for the validation of the fire danger maps in order to create the basic elements for the design of a validation protocol.

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

    NASA Astrophysics Data System (ADS)

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

    2013-09-01

    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 period. While the spatial distribution and seasonal variability of CALIPSO AOD is generally consistent with that of MODIS, CALIPSO is overall lower than MODIS as MODIS has higher frequency than CALIPSO for most bins of AOD. The correlation between MODIS and CALIPSO is better over ocean than over land. We focused on four regions that have large systematic differences: two over dust regions (the Sahara and Northwest China) and two over biomass burning regions (South Africa and South America). It is found that CALIPSO AOD is significantly lower than MODIS AOD over dust regions during the whole time period, with a maximum difference of 0.3 over the Saharan region and 0.25 over Northwest China. For biomass burning regions, CALIPSO AOD is significantly higher than MODIS AOD over South Africa, with a maximum difference of 0.25. Additionally CALIPSO AOD is slightly higher than MODIS AOD over South America for most of the time period, with a few exceptions in 2006, 2007, and 2010, when biomass burning is significantly stronger than during other years. We analyzed the impact of the satellite spatial and temporal sampling issue by using level 2 CALIPSO and MODIS products, and these systematic differences can still be found. The results of this study indicate that systematic differences of CALIPSO relative to MODIS are closely associated with aerosol types, which vary by location and season. Large differences over dust and biomass burning regions may suggest that assumptions made in satellite 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 the MODIS algorithm, are not appropriate.

  12. Terra and Aqua: new data for epidemiology and public health

    PubMed Central

    Tatem, Andrew J.; Goetz, Scott J.; Hay, Simon I.

    2012-01-01

    Earth-observing satellites have only recently been exploited for the measurement of environmental variables of relevance to epidemiology and public health. Such work has relied on sensors with spatial, spectral and geometric constraints that have allowed large-area questions associated with the epidemiology of vector-borne diseases to be addressed. Moving from pretty maps to pragmatic control tools requires a suite of satellite-derived environmental data of higher fidelity, spatial resolution, spectral depth and at similar temporal resolutions to existing meteorological satellites. Information derived from sensors onboard the next generation of moderate-resolution Earth-observing sensors may provide the key. The MODIS and ASTER sensors onboard the Terra and Aqua platforms provide substantial improvements in spatial resolution, number of spectral channels, choices of bandwidths, radiometric calibration and a much-enhanced set of pre-processed and freely available products. These sensors provide an important advance in moderate-resolution remote sensing and the data available to those concerned with improving public health. PMID:22545030

  13. Terra and Aqua: new data for epidemiology and public health

    NASA Astrophysics Data System (ADS)

    Tatem, Andrew J.; Goetz, Scott J.; Hay, Simon I.

    2004-11-01

    Earth-observing satellites have only recently been exploited for the measurement of environmental variables of relevance to epidemiology and public health. Such work has relied on sensors with spatial, spectral and geometric constraints that have allowed large-area questions associated with the epidemiology of vector-borne diseases to be addressed. Moving from pretty maps to pragmatic control tools requires a suite of satellite-derived environmental data of higher fidelity, spatial resolution, spectral depth and at similar temporal resolutions to existing meteorological satellites. Information derived from sensors onboard the next generation of moderate-resolution Earth-observing sensors may provide the key. The MODIS and ASTER sensors onboard the Terra and Aqua platforms provide substantial improvements in spatial resolution, number of spectral channels, choices of bandwidths, radiometric calibration and a much-enhanced set of pre-processed and freely available products. These sensors provide an important advance in moderate-resolution remote sensing and the data available to those concerned with improving public health.

  14. MODIS Data and Services at the National Snow and Ice Data Center (NSIDC)

    NASA Astrophysics Data System (ADS)

    McAllister, M.; Booker, L.; Fowler, D. K.; Haran, T. M.

    2014-12-01

    For close to 15 years, the National Snow and Ice Data Center (NSIDC) NASA Distributed Active Archive Center (NDAAC) has archived and distributed snow and sea ice products derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) instruments on the NASA Earth Observing System (EOS) Aqua and Terra satellites. The archive contains a wide selection of snow and sea ice data products relevant to cryospheric science. NSIDC offers a variety of methods for obtaining these data. Users can ftp data directly from an online archive which allows for a very quick download. The Reverb Search & Order Tool contains a complete set of metadata for all products which can be searched for and ordered. Reverb allows a user to order spatial, temporal, and parameter subsets of the data. Users can also request that they be added to our subscription list which makes it possible to have new MODIS data automatically ftp'd or staged on a local server as it is archived at NSIDC. Since MODIS products are in HDF-EOS format, a number of tools have been developed to assist with browsing, editing, reprojection, resampling, and format conversion. One such service, Data Access, can be accessed through Reverb and performs subsetting, reformatting, and reprojection. This service can also be accessed via an Application Programming Interface (API) from a user-written client. Other tools include the MODIS Swath-to-Grid Toolbox (MS2GT) and the MODIS Interactive Subsetting Tool (MIST). MS2GT was created to produce a seamless output grid from multiple input files corresponding to successively acquired, 5-minute MODIS scenes. NSIDC also created the MIST to provide subsets of certain Version 5 MODIS products, over the Greenland Climate Network (GC-Net) and the International Arctic Systems for Observing the Atmosphere (IASOA) stations. Tools from other sources include HDFView from the National Center for Supercomputing Applications (NCSA), and the MODIS Reprojection Tool (MRT) and MRT Swath developed by the Land Processes DAAC (LP-DAAC).

  15. MODIS 3 Km Aerosol Product: Applications over Land in an Urban/suburban Region

    NASA Technical Reports Server (NTRS)

    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.

  16. Estimation of Surface Air Temperature from MODIS 1km Resolution Land Surface Temperature Over Northern China

    NASA Technical Reports Server (NTRS)

    Shen, Suhung; Leptoukh, Gregory G.; Gerasimov, Irina

    2010-01-01

    Surface air temperature is a critical variable to describe the energy and water cycle of the Earth-atmosphere system and is a key input element for hydrology and land surface models. It is a very important variable in agricultural applications and climate change studies. This is a preliminary study to examine statistical relationships between ground meteorological station measured surface daily maximum/minimum air temperature and satellite remotely sensed land surface temperature from MODIS over the dry and semiarid regions of northern China. Studies were conducted for both MODIS-Terra and MODIS-Aqua by using year 2009 data. Results indicate that the relationships between surface air temperature and remotely sensed land surface temperature are statistically significant. The relationships between the maximum air temperature and daytime land surface temperature depends significantly on land surface types and vegetation index, but the minimum air temperature and nighttime land surface temperature has little dependence on the surface conditions. Based on linear regression relationship between surface air temperature and MODIS land surface temperature, surface maximum and minimum air temperatures are estimated from 1km MODIS land surface temperature under clear sky conditions. The statistical errors (sigma) of the estimated daily maximum (minimum) air temperature is about 3.8 C(3.7 C).

  17. Corrections to MODIS Terra Calibration and Polarization Trending Derived from Ocean Color Products

    NASA Technical Reports Server (NTRS)

    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).

  18. Fire Radiative Energy and Biomass Burned Estimation Under Sparse Satellite Sampling Conditions: Using Power Law Probability Distribution Properties of MODIS Fire Radiative Power Retrievals

    NASA Astrophysics Data System (ADS)

    Sathyachandran, S.; Roy, D. P.; Boschetti, L.

    2010-12-01

    Spatially and temporally explicit mapping of the amount of biomass burned by fire is needed to estimate atmospheric emissions of green house gases and aerosols. The instantaneous Fire Radiative Power (FRP) [units: W] is retrieved at active fire detections from mid-infrared wavelength remotely sensed data and can be used to estimate the rate of biomass consumed. Temporal integration of FRP measurements over the duration of the fire provides the Fire Radiative Energy (FRE) [units: J] that has been shown to be linearly related to the total biomass burned [units: g]. However, FRE, and thus biomass burned retrieval, is sensitive to the satellite spatial and temporal sampling of FRP which can be sparse under cloudy conditions and with polar orbiting sensors such as MODIS. In this paper the FRE is derived in a new way as the product of the fire duration and the first moment of the FRP power law probability distribution. MODIS FRP data retrieved over savanna fires in Australia and deforestation fires in Brazil are shown to have power law distributions with different scaling parameters that are related to the fire energy in these two contrasting systems. The FRE derived burned biomass estimates computed using this new method are compared to estimates using the conventional temporal FRP integration method and with literature values. The results of the comparison suggest that the new method may provide more reliable burned biomass estimates under sparse satellite sampling conditions if the fire duration and the power law distribution parameters are characterized a priori.

  19. Monitoring Seasonality in Phenology of Amazonian Rainforests Using MISR and MODIS Data

    NASA Astrophysics Data System (ADS)

    Knyazikhin, Y.; Bi, J.; CHOI, S.; Park, T.; Myneni, R. B.

    2014-12-01

    Monitoring of dense vegetation such as Amazonian rainforests represents the most complicated case in remote sensing because reflectances saturate and are weakly sensitive to changes in canopy properties. A new approach to interpret such data based on analyses of angular signatures of radiation reflected by dense vegetation is discussed in this poster. This approach was applied to monitor seasonality in phenology of Amazonian rainforests using data from Terra MODIS, MISR and Aqua MODIS sensors. These three independent satellite datasets consistently show higher greenness level during the dry season relative to the wet season. This result is consistent with the light limitation hypothesis, i.e., light is the limiting factor for productivity of well-hydrated equatorial Amazonian rainforests.

  20. MODIS Radiometric Calibration and Uncertainty Assessment

    NASA Technical Reports Server (NTRS)

    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.

  1. Use of MODIS-Derived Fire Radiative Energy to Estimate Smoke Aerosol Emissions over Different Ecosystems

    NASA Technical Reports Server (NTRS)

    Ichoku, Charles; Kaufman, Yoram J.

    2003-01-01

    Biomass burning is the main source of smoke aerosols and certain trace gases in the atmosphere. However, estimates of the rates of biomass consumption and emission of aerosols and trace gases from fires have not attained adequate reliability thus far. Traditional methods for deriving emission rates employ the use of emission factors e(sub x), (in g of species x per kg of biomass burned), which are difficult to measure from satellites. In this era of environmental monitoring from space, fire characterization was not a major consideration in the design of the early satellite-borne remote sensing instruments, such as AVHRR. Therefore, although they are able to provide fire location information, they were not adequately sensitive to variations in fire strength or size, because their thermal bands used for fire detection saturated at the lower end of fire radiative temperature range. As such, hitherto, satellite-based emission estimates employ proxy techniques using satellite derived fire pixel counts (which do not express the fire strength or rate of biomass consumption) or burned areas (which can only be obtained after the fire is over). The MODIS sensor, recently launched into orbit aboard EOS Terra (1999) and Aqua (2002) satellites, have a much higher saturation level and can, not only detect the fire locations 4 times daily, but also measures the at-satellite fire radiative energy (which is a measure of the fire strength) based on its 4 micron channel temperature. Also, MODIS measures the optical thickness of smoke and other aerosols. Preliminary analysis shows appreciable correlation between the MODIS-derived rates of emission of fire radiative energy and smoke over different regions across the globe. These relationships hold great promise for deriving emission coefficients, which can be used for estimating smoke aerosol emissions from MODIS active fire products. This procedure has the potential to provide more accurate emission estimates in near real-time, providing opportunities for various disaster management applications such as alerts, evacuation and, smoke dispersion forecasting.

  2. CERES Monthly Gridded Single Satellite TOA and Surfaces/Clouds(SFC) data in HDF (CER_SFC_Aqua-FM3-MODIS_Edition1B)

    NASA Technical Reports Server (NTRS)

    Wielicki, Bruce A. (Principal Investigator)

    The Monthly Gridded TOA/Surface Fluxes and Clouds (SFC) product contains a month of space and time averaged Clouds and the Earth's Radiant Energy System (CERES) data for a single scanner instrument. The SFC is also produced for combinations of scanner instruments. All instantaneous shortwave, longwave, and window fluxes at the Top-of-the-Atmosphere (TOA) and surface from the CERES SSF product for a month are sorted by 1-degree spatial regions and by the local hour of observation. The mean of the instantaneous fluxes for a given region-hour bin is determined and recorded on the SFC along with other flux statistics and scene information. These average fluxes are given for both clear-sky and total-sky scenes. The regional cloud properties are column averaged and are included on the SFC. [Location=GLOBAL] [Temporal_Coverage: Start_Date=1998-01-01; Stop_Date=2005-03-31] [Spatial_Coverage: Southernmost_Latitude=-90; Northernmost_Latitude=90; Westernmost_Longitude=-180; Easternmost_Longitude=100] [Data_Resolution: Latitude_Resolution=1 degree; Longitude_Resolution=1 degree; Horizontal_Resolution_Range=100 km - < 250 km or approximately 1 degree - < 2.5 degrees; Temporal_Resolution=1 hour; Temporal_Resolution_Range=Hourly - < Daily].

  3. CERES Monthly Gridded Single Satellite TOA and Surfaces/Clouds (SFC) data in HDF (CER_SFC_Aqua-FM3-MODIS_Edition2A)

    NASA Technical Reports Server (NTRS)

    Wielicki, Bruce A. (Principal Investigator)

    The Monthly Gridded TOA/Surface Fluxes and Clouds (SFC) product contains a month of space and time averaged Clouds and the Earth's Radiant Energy System (CERES) data for a single scanner instrument. The SFC is also produced for combinations of scanner instruments. All instantaneous shortwave, longwave, and window fluxes at the Top-of-the-Atmosphere (TOA) and surface from the CERES SSF product for a month are sorted by 1-degree spatial regions and by the local hour of observation. The mean of the instantaneous fluxes for a given region-hour bin is determined and recorded on the SFC along with other flux statistics and scene information. These average fluxes are given for both clear-sky and total-sky scenes. The regional cloud properties are column averaged and are included on the SFC. [Location=GLOBAL] [Temporal_Coverage: Start_Date=1998-01-01; Stop_Date=2005-12-31] [Spatial_Coverage: Southernmost_Latitude=-90; Northernmost_Latitude=90; Westernmost_Longitude=-180; Easternmost_Longitude=100] [Data_Resolution: Latitude_Resolution=1 degree; Longitude_Resolution=1 degree; Horizontal_Resolution_Range=100 km - < 250 km or approximately 1 degree - < 2.5 degrees; Temporal_Resolution=1 hour; Temporal_Resolution_Range=Hourly - < Daily].

  4. CERES Monthly Gridded Single Satellite TOA and Surfaces/Clouds (SFC) data in HDF (CER_SFC_Aqua-FM4-MODIS_Edition2A)

    NASA Technical Reports Server (NTRS)

    Wielicki, Bruce A. (Principal Investigator)

    The Monthly Gridded TOA/Surface Fluxes and Clouds (SFC) product contains a month of space and time averaged Clouds and the Earth's Radiant Energy System (CERES) data for a single scanner instrument. The SFC is also produced for combinations of scanner instruments. All instantaneous shortwave, longwave, and window fluxes at the Top-of-the-Atmosphere (TOA) and surface from the CERES SSF product for a month are sorted by 1-degree spatial regions and by the local hour of observation. The mean of the instantaneous fluxes for a given region-hour bin is determined and recorded on the SFC along with other flux statistics and scene information. These average fluxes are given for both clear-sky and total-sky scenes. The regional cloud properties are column averaged and are included on the SFC. [Location=GLOBAL] [Temporal_Coverage: Start_Date=1998-01-01; Stop_Date=2005-03-31] [Spatial_Coverage: Southernmost_Latitude=-90; Northernmost_Latitude=90; Westernmost_Longitude=-180; Easternmost_Longitude=100] [Data_Resolution: Latitude_Resolution=1 degree; Longitude_Resolution=1 degree; Horizontal_Resolution_Range=100 km - < 250 km or approximately 1 degree - < 2.5 degrees; Temporal_Resolution=1 hour; Temporal_Resolution_Range=Hourly - < Daily].

  5. CERES Monthly Gridded Single Satellite TOA and Surfaces/Clouds(SFC) data in HDF (CER_SFC_Aqua-FM4-MODIS_Edition1B)

    NASA Technical Reports Server (NTRS)

    Wielicki, Bruce A. (Principal Investigator)

    The Monthly Gridded TOA/Surface Fluxes and Clouds (SFC) product contains a month of space and time averaged Clouds and the Earth's Radiant Energy System (CERES) data for a single scanner instrument. The SFC is also produced for combinations of scanner instruments. All instantaneous shortwave, longwave, and window fluxes at the Top-of-the-Atmosphere (TOA) and surface from the CERES SSF product for a month are sorted by 1-degree spatial regions and by the local hour of observation. The mean of the instantaneous fluxes for a given region-hour bin is determined and recorded on the SFC along with other flux statistics and scene information. These average fluxes are given for both clear-sky and total-sky scenes. The regional cloud properties are column averaged and are included on the SFC. [Location=GLOBAL] [Temporal_Coverage: Start_Date=1998-01-01; Stop_Date=2005-03-31] [Spatial_Coverage: Southernmost_Latitude=-90; Northernmost_Latitude=90; Westernmost_Longitude=-180; Easternmost_Longitude=100] [Data_Resolution: Latitude_Resolution=1 degree; Longitude_Resolution=1 degree; Horizontal_Resolution_Range=100 km - < 250 km or approximately 1 degree - < 2.5 degrees; Temporal_Resolution=1 hour; Temporal_Resolution_Range=Hourly - < Daily].

  6. Overview of CERES Cloud Properties Derived From VIRS AND MODIS DATA

    NASA Technical Reports Server (NTRS)

    Minis, Patrick; Geier, Erika; Wielicki, Bruce A.; Sun-Mack, Sunny; Chen, Yan; Trepte, Qing Z.; Dong, Xiquan; Doelling, David R.; Ayers, J. Kirk; Khaiyer, Mandana M.

    2006-01-01

    Simultaneous measurement of radiation and cloud fields on a global basis is recognized as a key component in understanding and modeling the interaction between clouds and radiation at the top of the atmosphere, at the surface, and within the atmosphere. The NASA Clouds and Earth s Radiant Energy System (CERES) Project (Wielicki et al., 1998) began addressing this issue in 1998 with its first broadband shortwave and longwave scanner on the Tropical Rainfall Measuring Mission (TRMM). This was followed by the launch of two CERES scanners each on Terra and Aqua during late 1999 and early 2002, respectively. When combined, these satellites should provide the most comprehensive global characterization of clouds and radiation to date. Unfortunately, the TRMM scanner failed during late 1998. The Terra and Aqua scanners continue to operate, however, providing measurements at a minimum of 4 local times each day. CERES was designed to scan in tandem with high resolution imagers so that the cloud conditions could be evaluated for every CERES measurement. The cloud properties are essential for converting CERES radiances shortwave albedo and longwave fluxes needed to define the radiation budget (ERB). They are also needed to unravel the impact of clouds on the ERB. The 5-channel, 2-km Visible Infrared Scanner (VIRS) on the TRMM and the 36-channel 1-km Moderate Resolution Imaging Spectroradiometer (MODIS) on Terra and Aqua are analyzed to define the cloud properties for each CERES footprint. To minimize inter-satellite differences and aid the development of useful climate-scale measurements, it was necessary to ensure that each satellite imager is calibrated in a fashion consistent with its counterpart on the other CERES satellites (Minnis et al., 2006) and that the algorithms are as similar as possible for all of the imagers. Thus, a set of cloud detection and retrieval algorithms were developed that could be applied to all three imagers utilizing as few channels as possible while producing stable and accurate cloud properties. This paper discusses the algorithms and results of applying those techniques to more than 5 years of Terra MODIS, 3 years of Aqua MODIS, and 4 years of TRMM VIRS data.

  7. Depolarization ratio and attenuated backscatter for nine cloud types: analyses based on collocated CALIPSO lidar and MODIS measurements.

    PubMed

    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 the CALIPSO delta-gamma' relationship. PMID:18542490

  8. Improvements to the MODIS Land Products in Collection Version 6

    NASA Astrophysics Data System (ADS)

    Wolfe, R. E.; Devadiga, S.; Masuoka, E. J.; Running, S. W.; Vermote, E.; Giglio, L.; Wan, Z.; Riggs, G. A.; Schaaf, C.; Myneni, R. B.; Friedl, M. A.; Wang, Z.; Sulla-menashe, D. J.; Zhao, M.

    2013-12-01

    The MODIS (Moderate Resolution Imaging Spectroradiometer) Adaptive Processing System (MODAPS), housed at the NASA Goddard Space Flight Center (GSFC), has been processing the earth view data acquired by the MODIS instrument aboard the Terra (EOS AM) and Aqua (EOS PM) satellites to generate suite of land and atmosphere data products using the science algorithms developed by the MODIS Science Team. These data products are used by diverse set of users in research and other applications from both government and non-government agencies around the world. These validated global products are also being used in interactive Earth system models able to predict global change accurately enough to assist policy makers in making sound decisions concerning the protection of our environment. Hence an increased emphasis is being placed on generation of high quality consistent data records from the MODIS data through reprocessing of the records using improved science algorithms. Since the launch of Terra in December 1999, MODIS land data records have been reprocessed four times. The Collection Version 6 (C6) reprocessing of MODIS Land and Atmosphere products is scheduled to start in Fall 2013 and is expected to complete in Spring 2014. This presentation will describe changes made to the C6 science algorithms to correct issues in the C5 products, additional improvements made to the products as deemed necessary by the data users and science teams, and new products introduced in this reprocessing. In addition to the improvements from product specific changes to algorithms, the C6 products will also see significant improvement in the calibration by the MODIS Calibration Science Team (MCST) of the C6 L1B Top of the Atmosphere (TOA) reflectance and radiance product, more accurate geolocation, and an improved Land Water mask. For the a priori land cover input, this reprocessing will use the multi-year land cover product generated with three years of MODIS data as input as opposed to one single land cover product used for the entire mission in the C5 reprocessing. The C6 products are expected to be released from the Distributed Active Archive Center (DAAC) soon after the reprocessing begins. To facilitate user acquaintance with products from the new version and independent evaluation of C6 by comparison of two versions, MODAPS plans to continue generation of products from both versions for at least a year after completion of the C6 reprocessing after which C5 processing will be discontinued.

  9. Validation of AIRS/AMSU Cloud Retrievals Using MODIS Cloud Analyses

    NASA Technical Reports Server (NTRS)

    Molnar, Gyula I.; Susskind, Joel

    2005-01-01

    The AIRS/AMSU (flying on the EOS-AQUA satellite) sounding retrieval methodology allows for the retrieval of key atmospheric/surface parameters under partially cloudy conditions (Susskind et al.). In addition, cloud parameters are also derived from the AIRS/AMSU observations. Within each AIRS footprint, cloud parameters at up to 2 cloud layers are determined with differing cloud top pressures and effective (product of infrared emissivity at 11 microns and physical cloud fraction) cloud fractions. However, so far the AIRS cloud product has not been rigorously evaluated/validated. Fortunately, collocated/coincident radiances measured by MODIS/AQUA (at a much lower spectral resolution but roughly an order of-magnitude higher spatial resolution than that of AIRS) are used to determine analogous cloud products from MODIS. This allows us for a rather rare and interesting possibility: the intercomparisons and mutual validation of imager vs. sounder-based cloud products obtained from the same satellite positions. First, we present results of small-scale (granules) instantaneous intercomparisons. Next, we will evaluate differences of temporally averaged (monthly) means as well as the representation of inter-annual variability of cloud parameters as presented by the two cloud data sets. In particular, we present statistical differences in the retrieved parameters of cloud fraction and cloud top pressure. We will investigate what type of cloud systems are retrieved most consistently (if any) with both retrieval schemes, and attempt to assess reasons behind statistically significant differences.

  10. Validation of MODIS aerosol optical depth over the Mediterranean Coast

    NASA Astrophysics Data System (ADS)

    Daz-Martnez, J. Vicente; Segura, Sara; Estells, Vctor; Utrillas, M. Pilar; Martnez-Lozano, J. Antonio

    2013-04-01

    Atmospheric aerosols, due to their high spatial and temporal variability, are considered one of the largest sources of uncertainty in different processes affecting visibility, air quality, human health, and climate. Among their effects on climate, they play an important role in the energy balance of the Earth. On one hand they have a direct effect by scattering and absorbing solar radiation; on the other, they also have an impact in precipitation, modifying clouds, or affecting air quality. The application of remote sensing techniques to investigate aerosol effects on climate has advanced significatively over last years. In this work, the products employed have been obtained from the Moderate Resolution Imaging Spectroradiometer (MODIS). MODIS is a sensor located onboard both Earth Observing Systems (EOS) Terra and Aqua satellites, which provide almost complete global coverage every day. These satellites have been acquiring data since early 2000 (Terra) and mid 2002 (Aqua) and offer different products for land, ocean and atmosphere. Atmospheric aerosol products are presented as level 2 products with a pixel size of 10 x 10 km2 in nadir. MODIS aerosol optical depth (AOD) is retrieved by different algorithms depending on the pixel surface, distinguishing between land and ocean. For its validation, ground based sunphotometer data from AERONET (Aerosol Robotic Network) has been employed. AERONET is an international operative network of Cimel CE318 sky-sunphotometers that provides the most extensive aerosol data base globally available of ground-based measurements. The ground sunphotometric technique is considered the most accurate for the retrieval of radiative properties of aerosols in the atmospheric column. In this study we present a validation of MODIS C051 AOD employing AERONET measurements over different Mediterranean coastal sites centered over an area of 50 x 50 km2, which includes both pixels over land and ocean. The validation is done comparing spatial statistics from MODIS with corresponding temporal statistics from AERONET, as proposed by Ichoku et al. (2002). Eight Mediterranean coastal sites (in Spain, France, Italy, Crete, Turkey and Israel) with available AERONET and MODIS data have been used. These stations have been selected following QA criteria (minimum 1000 days of level 2.0 data) and a maximum distance of 8 km from the coast line. Results of the validation over each site show analogous behaviour, giving similar results regarding to the accuracy of the algorithms. Greatest differences are found for the AOD obtained over land, especially for drier regions, where the surface tends to be brighter. In general, the MODIS AOD has better a agreement with AERONET retrievals for the ocean algorithm than the land algorithm when validated over coastal sites, and the agreement is within the expected uncertainty estimated for MODIS data. References: - C. Ichoku et al., "A spatio-temporal approach for global validation and analysis of MODIS aerosol products", Geophysical Research Letters, 219, 12, 10.1029/2001GL013206, 2002.

  11. Polarization Modeling of the MODIS Instrument

    NASA Technical Reports Server (NTRS)

    Waluschka, Eugene; Xiong, Xiao-Xiong; Esaias, Wayne E.; Voss, Kenneth; Souaidia, Nordine; Pellicori, Samuel; Moyer, David; Guenther, Bruce; Barnes, William

    2004-01-01

    Sunlight reflected from the earth is, to a certain extent, polarized. Radiometers, such as the MODIS instrument on board the TERRA and AQUA spacecraft, are to a certain extent polarizers. Accurate radiometric measurements must take into account both the polarization state of the scene and the polarization sensitivity of the measuring instrument. The measured polarization characteristics of the MODIS instruments are contained in various radiometric models. Continued use of these radiometric math models, over a number of years, have shown where these models can be improved. The current MODIS polarization modeling effort is discussed in the context and limitations of past modeling efforts.

  12. Detection of irrigation timing using MODIS and SAR: Effect of land cover heterogeneity

    NASA Astrophysics Data System (ADS)

    Seungtaek, J.; Keunchang, J.; Lee, H.; Seokyeong, H.; Kang, S.

    2010-12-01

    Rice is one of the world’s major staple foods. Paddy rice fields had unique biophysical characteristics that the rice is grown on flooded soils unlike other crops. Distribution and timing of irrigation of paddy rice fields are of importance to determine hydrological balance and efficiency of water resource. In this paper, we detected the distribution and timing of irrigation of paddy rice fields using the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor onboard the NASA EOS Aqua satellite. Previous researches demonstrated that MODIS data can be utilized to detect timing of irrigation by combining vegetation index and Land Surface Water Index (LSWI). Land cover heterogeneity, however, causes considerable uncertainty of the satellite-based detections. To evaluate and quantify the effect of land cover heterogeneity, Radarsat-1 Synthetic Aperture Radar (SAR) images were applied together with the MODIS images. Sub-pixel heterogeneity of MODIS image on land cover and irrigation was evaluated and quantified by using the Radarsat-1 SAR images. The degree of sub-pixel heterogeneity was related with detection of a threshold value of LSWI to determine the timing of irrigation. The threshold value with the degree of heterogeneity increased (R2=0.95), which was applied to detect the timing of irrigation over complex land cover areas. Reliable detecting of timing of irrigation could enhance reliability of MODIS-based estimation on evapotranspiration from paddy rice fields. In this presentation, we will demonstrate the enhancement of MODIS-based evapotranspiration by using our new algorithm on detection of timing of irrigation. Acknowledgement: This study was supported by National Academy of Agricultural Science, RDA, Republic of Korea.

  13. Tracking daily land surface albedo and reflectance anisotropy with moderate-resolution imaging spectroradiometer (MODIS)

    NASA Astrophysics Data System (ADS)

    Shuai, Yanmin

    A new algorithm provides daily values of land surface albedo and angular reflectance at a 500-m spatial resolution using data from the Moderate Resolution Imaging Spectroradiometer (MODIS) instruments currently in orbit on NASA's Terra and Aqua satellite platforms. To overcome the day-to-day variance in observed surface reflectance induced by differences in view and solar illumination angles, the algorithm uses the RossThickLiSparse-Reciprocal bidirectional reflectance model, which is fitted to all MODIS observations of a 500-m resolution cell acquired during a 16-day moving window. Individual observations are weighted by their quality, observation coverage, and proximity to the production date of interest. Product quality is measured by (1) the root mean square error (RMSE) of observations against the best model fit; and (2) the ability of the angular sampling pattern of the observations at hand to determine reflectance model parameters accurately. A regional analysis of model fits to data from selected MODIS data tiles establishes the bounds of these quality measures for application in the daily algorithm. The algorithm, which is now available to users of direct broadcast satellite data from MODIS, allows daily monitoring of rapid surface radiation and land surface change phenomena such as crop development and forest foliage cycles. In two demonstrations, the daily algorithm captured rapid change in plant phenology. The growth phases of a winter wheat crop, as monitored at the Yucheng agricultural research station in Yucheng, China, matched MODIS daily multispectral reflectance data very well, especially during the flowering and heading stages. The daily algorithm also captured the daily change in autumn leaf color in New England, documenting the ability of the algorithm to work well over large regions with varying degrees of cloud cover and atmospheric conditions. Daily surface albedos measured using ground-based instruments on towers at the agricultural and forest locations also compared very favorably with the MODIS albedo measures derived with the new daily algorithm, achieving RMSE values of less than 0.03 units.

  14. MODIS-Derived Terrestrial Primary Production

    NASA Astrophysics Data System (ADS)

    Zhao, Maosheng; Running, Steven; Heinsch, Faith Ann; Nemani, Ramakrishna

    Temporal and spatial changes in terrestrial biological productivity have a large impact on humankind because terrestrial ecosystems not only create environments suitable for human habitation, but also provide materials essential for survival, such as food, fiber and fuel. A recent study estimated that consumption of terrestrial net primary production (NPP; a list of all the acronyms is available in the appendix at the end of the chapter) by the human population accounts for about 14-26% of global NPP (Imhoff et al. 2004). Rapid global climate change is induced by increased atmospheric greenhouse gas concentration, especially CO2, which results from human activities such as fossil fuel combustion and deforestation. This directly impacts terrestrial NPP, which continues to change in both space and time (Melillo et al. 1993; Prentice et al. 2001; Nemani et al. 2003), and ultimately impacts the well-being of human society (Milesi et al. 2005). Additionally, substantial evidence show that the oceans and the biosphere, especially terrestrial ecosystems, currently play a major role in reducing the rate of the atmospheric CO2 increase (Prentice et al. 2001; Schimel et al. 2001). NPP is the first step needed to quantify the amount of atmospheric carbon fixed by plants and accumulated as biomass. Continuous and accurate measurements of terrestrial NPP at the global scale are possible using satellite data. Since early 2000, for the first time, the MODIS sensors onboard the Terra and Aqua satellites, have operationally provided scientists with near real-time global terrestrial gross primary production (GPP) and net photosynthesis (PsnNet) data. These data are provided at 1 km spatial resolution and an 8-day interval, and annual NPP covers 109,782,756 km2 of vegetated land. These GPP, PsnNet and NPP products are collectively known as MOD17 and are part of a larger suite of MODIS land products (Justice et al. 2002), one of the core Earth System or Climate Data Records (ESDR or CDR).

  15. MODIS Data and Services at the National Snow and Ice Data Center (NSIDC)

    NASA Astrophysics Data System (ADS)

    McAllister, M.; Fowler, D. K.

    2010-12-01

    For nearly a decade, the National Snow and Ice Data Center (NSIDC) has archived and distributed snow and sea ice products derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) instruments on the NASA Earth Observing System (EOS) Aqua and Terra satellites. The archive contains a wide selection of data products relevant to cryospheric science, including snow and sea ice. NSIDC offers a variety of methods for obtaining these data. Our Data Pool is an online archive which allows a user to very quickly download desired products and also has a spatial and temporal search capability. The Warehouse Inventory Search Tool (WIST) contains a complete set of metadata for all products which can be searched for and ordered. WIST also allows a user to order spatial, temporal, and parameter subsets of the data. Users can also request that they be added to our subscription list which makes it possible to have new MODIS data automatically ftp’d or staged on a local server as it is archived at NSIDC. Since MODIS products are in HDF-EOS format, NSIDC has developed a number of tools to assist with browsing, editing, reprojection, resampling, and format conversion including MODIS Swath-to-Grid Toolbox (MS2GT) and the MODIS Interactive Subsetting Tool (MIST). MS2GT was created to produce a seamless output grid from multiple input files corresponding to successively acquired, 5-minute MODIS scenes. NSIDC created the MIST to also provide subsets of certain Version 5 MODIS products, over the Greenland Climate Network (GC-Net) and the International Arctic Systems for Observing the Atmosphere (IASOA) stations.

  16. On-Orbit Characterization of MODIS Modulation Transfer Function Using the Moon

    NASA Technical Reports Server (NTRS)

    Wang, Zhipeng; Xiong, Xiaoxiong; Choi, Taeyoung; Link, Daniel

    2013-01-01

    The high-contrast edge of the Moon has been used for the on-orbit measurement of the modulation transfer function (MTF) of remote sensing instruments with a lunar observation capability. With the lunar edge as a target, the classical edge method is applied to the National Aeronautics and Space Administration's MODerate resolution Imaging Spectror-Radiometer (MODIS) on board the Terra and Aqua satellites. One of the major difficulties encountered during the calculation is that the spatial resolution of MODIS is too coarse to capture the fine structure of the edge spread function (ESF), which is required to calculate the MTF. To produce the MODIS ESF in high resolution, lunar images of a selected edge acquired by multiple instrument scans need to be superposed by aligning the edge positions accurately. In this paper, an algorithm is developed to perform the alignment, based on the lunar position data generated by the MODIS geo-location algorithm and recorded scan by scan. The positions of the lunar edges at the focal plane are calculated scan by scan, allowing the construction of a high-quality ESF for MTF derivation. The algorithm is applied to all MODIS bands with 250-m, 500-m, and 1-km spatial resolutions in both along-scan and along-track directions. The along-track MTF results are particularly valuable because the onboard Spectro-Radiometric Calibration Assembly can only monitor the along-scan MTF. The trending results show that the along-track MTF of MODIS has been stable throughout the MODIS lifetime and is well above the design specification for all bands. The limitation of the algorithm is analyzed. The algorithm developed in this paper can be applied to other instruments with similar design features.

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

    NASA Astrophysics Data System (ADS)

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

    2012-11-01

    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, are not appropriate. Further research is needed to narrow down the exact source of bias in order to improve the satellite retrievals.

  18. River runoff effect on the suspended sediment property in the upper Chesapeake Bay using MODIS observations and ROMS simulations

    NASA Astrophysics Data System (ADS)

    Liu, Xiaoming; Wang, Menghua

    2014-12-01

    Ocean color data derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) on the satellite Aqua from 2002 to 2012 and simulations from the Regional Ocean Modeling System (ROMS) are used to study the impact of the Susquehanna River discharge on the total suspended sediment (TSS) concentration in the upper Chesapeake Bay. Since the water in the upper Chesapeake Bay is highly turbid, the shortwave infrared (SWIR)-based atmospheric correction algorithm is used for deriving the normalized water-leaving radiance nLw(λ) spectra from MODIS-Aqua measurements. nLw(λ) spectra are further processed into the diffuse attenuation coefficient at the wavelength of 490 nm Kd(490) and TSS. MODIS-Aqua-derived monthly TSS concentration in the upper Chesapeake Bay and in situ Susquehanna River discharge data show similar patterns in seasonal variations. The TSS monthly temporal variation in the upper Chesapeake Bay is also found in phase with the monthly averaged river discharge data. Since the Susquehanna River discharge is mainly dominated by a few high discharge events due to winter-spring freshets or tropical storms in each year, the impact of these high discharge events on the upper Chesapeake Bay TSS is investigated. Both MODIS-measured daily TSS images and sediment data derived from ROMS simulations show that the Susquehanna River discharge is the dominant factor for the variations of TSS concentration in the upper Chesapeake Bay. Although the high river discharge event usually lasts for only a few days, its induced high TSS concentration in the upper Chesapeake Bay can sustain for ˜10-20 days. The elongated TSS rebounding stage is attributed to horizontal advection of slowly settling fine sediment from the Susquehanna River.

  19. Analysis of drought events in a Mediterranean semi-arid region, Using SPOT-VGT and TERRA-MODIS satellite products

    NASA Astrophysics Data System (ADS)

    Zribi, Mehrez; Dridi, Ghofrane; Amri, Rim; Lili-Chabaane, Zohra

    2015-04-01

    In semi-arid regions, and northern Africa in particular, the scarcity of rainfall and the occurrence of long periods of drought, represent one of the main environmental factors having a negative effect on agricultural productivity. This is the case in Central Tunisia, where the monitoring of agricultural and water resources is of prime importance. Vegetation cover is a key parameter to analyse this problem. Remote sensing has shown in the last decades a high potential to estimate these surface parameters. This study is based on two satellite products: SPOT-VGT (1998-2012) and TERRA-MODIS (2001-2012) NDVI products. They are used to study the dynamics of vegetation and land use. Different behaviors linked to drought periods have been observed. A strong agreement is observed between products proposed by the two sensors. Low spatial resolution SPOT-VGT and TERRA-MODIS NDVI images were used to map the land into three characteristic classes: olive trees, annual agriculture and pastures. An analysis of vegetation behaviour for dry years is proposed using the Windowed Fourier Transform (WTF). The Fourier Transform is able to analyze the frequency content of a signal in the time domain by decomposing the signal as the superposition of sine and cosine basis functions. Analysis for annual agricultural areas demonstrates a combined effect between climate and farmers behaviours. In these areas, bare soils show a high increasing for drought years. Highest percent of bare soil is retrieved with TERRA-MODIS than with SPOT-VGT. This could be explained by the spatial resolution of the two sensors. The temporal series of optical images are finally used to calculate a drought index, namely the VAI (Vegetation Anomaly Index), on the plain of Kairouan (Amri et al., 2011). This index shows a high correlation with precipitation statistics.

  20. Use of MODIS Satellite Images and an Atmospheric Dust Transport Model to Evaluate Juniperus spp. Pollen Phenology and Dispersal

    NASA Technical Reports Server (NTRS)

    Luvall, Jeffrey C.

    2011-01-01

    Pollen can be transported great distances. Van de Water et. al. reported Juniperus spp. pollen was transported 200-600 km. Hence local obse rvations of plant phenology may not be consistent with the timing and source of pollen collected by pollen sampling instruments. The DREAM (Dust REgional Atmospheric Model, Nickovic et al. 2001) is a verified model for atmospheric dust transport modeling using MODIS data produ cts to identify source regions and quantities of dust. We are modifyi ng the DREAM model to incorporate pollen transport. Pollen release wi ll be estimated based on MODIS derived phenology of Juniperus spp. communities. Ground based observations records of pollen release timing and quantities will be used as verification. This information will be used to support the Centers for Disease Control and Prevention?s Nat ional Environmental Public Health Tracking Program and the State of New Mexico environmental public health decision support for asthma and allergies alerts.

  1. Use of MODIS Satellite Images and an Atmospheric Dust Transport Model To Evaluate Juniperus spp. Pollen Phenology and Dispersal

    NASA Technical Reports Server (NTRS)

    Luvall, J. C.; Sprigg, W. A.; Levetin, Estelle; Huete, Alfredo; Nickovic, S.; Pejanovic, G. A.; Vukovic, A.; VandeWater, P. K.; Myers, O. B.; Budge, A. M.; Zelicoff, A. P.; Bunderson, L.; Crimmins, T. M.

    2011-01-01

    Pollen can be transported great distances. Van de Water et. al., 2003 reported Juniperus spp. pollen was transported 200-600 km. Hence local observations of plant phenology may not be consistent with the timing and source of pollen collected by pollen sampling instruments. The DREAM (Dust REgional Atmospheric Model, Nickovic et al. 2001) is a verified model for atmospheric dust transport modeling using MODIS data products to identify source regions and quantities of dust. We are modifying the DREAM model to incorporate pollen transport. Pollen release will be estimated based on MODIS derived phenology of Juniperus spp. communities. Ground based observational records of pollen release timing and quantities will be used as verification. This information will be used to support the Centers for Disease Control and Prevention's National Environmental Public Health Tracking Program and the State of New Mexico environmental public health decision support for asthma and allergies alerts.

  2. Use of MODIS Satellite Images and an Atmospheric Dust Transport Model to Evaluate Juniperus spp. Pollen Phenology and Dispersal

    NASA Technical Reports Server (NTRS)

    Luvall, J. C.; Sprigg, W. A.; Levetin, E.; Huete, A.; Nickovic, S.; Pejanovic, G. A.; Vukovic, A.; VandeWater, P. K.; Myers, O. B.; Budge, A. M.; Zelicoff, A. P.; Bunderson, L.; Crimmins, T. M.

    2011-01-01

    Pollen can be transported great distances. Van de Water et. al. reported Juniperus spp. pollen was transported 200-600 km. Hence local observations of plant phenology may not be consistent with the timing and source of pollen collected by pollen sampling instruments. The DREAM (Dust REgional Atmospheric Model) is a verified model for atmospheric dust transport modeling using MODIS data products to identify source regions and quantities of dust. We are modifying the DREAM model to incorporate pollen transport. Pollen release will be estimated based on MODIS derived phenology of Juniperus spp. communities. Ground based observational records of pollen release timing and quantities will be used as verification. This information will be used to support the Centers for Disease Control and Prevention's National Environmental Public Health Tracking Program and the State of New Mexico environmental public health decision support for asthma and allergies alerts.

  3. Analysis, improvement and application of the MODIS leaf area index products

    NASA Astrophysics Data System (ADS)

    Yang, Wenze

    Green leaf area governs the exchanges of energy, mass and momentum between the Earth's surface and the atmosphere. Therefore, leaf area index (LAI) and fraction of incident photosynthetically active radiation (0.4-0.7 mum) absorbed by the vegetation canopy (FPAR) are widely used in vegetation monitoring and modeling. The launch of Terra and Aqua satellites with the moderate resolution imaging spectroradiometer (MODIS) instrument onboard provided the first global products of LAI and FPAR, derived mainly from an algorithm based on radiative transfer. The objective of this research is to comprehensively evaluate the Terra and Aqua MODIS LAI/FPAR products. Large volumes of these products have been analyzed with the goal of understanding product quality with respect to version (Collection 3 versus 4), algorithm (main versus back-up), snow (snow-free versus snow on the ground) and cloud (cloud-free versus cloudy) conditions. Field validation efforts identified several key factors that influence the accuracy of algorithm retrievals. The strategy of validation efforts guiding algorithm refinements has led to progressively more accurate LAI/FPAR products. The combination of products derived from the Terra and Aqua MODIS sensors increases the success rate of the main radiative transfer algorithm by 10-20 percent over woody vegetation. The Terra Collection 4 LAI data reveal seasonal swings in green leaf area of about 25 percent in a majority of the Amazon rainforests caused by variability in cloud cover and light. The timing and the influence of this seasonal cycle are critical to understanding tropical plant adaptation patterns and ecological processes. The results presented in this dissertation suggest how the product quality has gradually improved largely through the efforts of validation activities. The Amazon case study highlights the utility of these data sets for monitoring global vegetation dynamics. Thus, these results can be seen as a benchmark for evaluation of future versions of similar products.

  4. Systematic errors in temperature estimates from MODIS data covering the western Palearctic and their impact on a parasite development model.

    PubMed

    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

  5. An Examination of the Nature of Global MODIS Cloud Regimes

    NASA Technical Reports Server (NTRS)

    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.

  6. Cloud removal methodology from MODIS snow cover product

    NASA Astrophysics Data System (ADS)

    Gafurov, Abror; Bárdossy, András.

    2010-05-01

    Snow plays an important role in hydrology, especially in mountain hydrology. Spatially continuous snow cover observation is only possible through airborne or satellite information. Moderate Resolution Imaging Spectroradiometer (MODIS) sensor installed onboard Terra and Aqua satellites provides among other datasets, binary snow cover information globally at 1 km spatial and daily temporal resolution. The main disadvantage of MODIS snow cover product is the cloud covered regions where no information about surface cover can be obtained. This study focuses on eliminating clouds from MODIS snow cover products and preparing cloud free snow maps for mountainous catchments. The MODSNOW algorithm was developed which consists of six subsequent steps where some cloud covered pixels are removed in each cloud elimination step using different temporal and spatial information. Cloud free 1 km spatial and daily temporal resolution snow cover data is the outcome of this algorithm. No clouds remain after application of all steps. A validation study showed that MODSNOW algorithm performed well in estimating surface cover for cloud covered pixels. Step one was not validated since this was based on satellite observations. Steps 2 to 5 resulted in the accuracy of 90-96 %. Step 6 which removes all remaining cloudy pixels performed least with about 80 % accuracy. Cloud free snow cover products can be very usefully applied in hydrological models, especially in mountain areas. Using MODSNOW algorithm, daily snow cover products were prepared for three Central Asian catchments which are located in mountainous areas. Such snow cover data can be used for hydropower operation, agriculture and many other environmental sectors in Central Asia. The MODSNOW algorithm can be used for any other region where snow cover information can be an important factor.

  7. Estimating Contrail Climate Effects from Satellite Data

    NASA Technical Reports Server (NTRS)

    Minnis, Patrick; Duda, David P.; Palikonda, Rabindra; Bedka, Sarah T.; Boeke, Robyn; Khlopenkov, Konstantin; Chee, Thad; Bedka, Kristopher T.

    2011-01-01

    An automated contrail detection algorithm (CDA) is developed to exploit six of the infrared channels on the 1-km MODerate-resolution Imaging Spectroradiometer (MODIS) on the Terra and Aqua satellites. The CDA is refined and balanced using visual error analysis. It is applied to MODIS data taken by Terra and Aqua over the United States during 2006 and 2008. The results are consistent with flight track data, but differ markedly from earlier analyses. Contrail coverage is a factor of 4 less than other retrievals and the retrieved contrail optical depths and radiative forcing are smaller by approx.30%. The discrepancies appear to be due to the inability to detect wider, older contrails that comprise a significant amount of the contrail coverage. An example of applying the algorithm to MODIS data over the entire Northern Hemisphere is also presented. Overestimates of contrail coverage are apparent in some tropical regions. Methods for improving the algorithm are discussed and are to be implemented before analyzing large amounts of Northern Hemisphere data. The results should be valuable for guiding and validating climate models seeking to account for aviation effects on climate.

  8. Assessment of satellite ocean color products of MERIS, MODIS and SeaWiFS along the East China Coast (in the Yellow Sea and East China Sea)

    NASA Astrophysics Data System (ADS)

    Cui, Tingwei; Zhang, Jie; Tang, Junwu; Sathyendranath, Shubha; Groom, Steve; Ma, Yi; Zhao, Wei; Song, Qingjun

    2014-01-01

    The validation of satellite ocean-color products is an important task of ocean-color missions. The uncertainties of these products are poorly quantified in the Yellow Sea (YS) and East China Sea (ECS), which are well known for their optical complexity and turbidity in terms of both oceanic and atmospheric optical properties. The objective of this paper is to evaluate the primary ocean-color products from three major ocean-color satellites, namely the Moderate Resolution Imaging Spectroradiometer (MODIS), Medium Resolution Imaging Spectrometer (MERIS), and Sea-viewing Wide Field-of-view Sensor (SeaWiFS). Through match-up analysis with in situ data, it is found that satellite retrievals of the spectral remote sensing reflectance Rrs(λ) at the blue-green and green bands from MERIS, MODIS and SeaWiFS have the lowest uncertainties with a median of the absolute percentage of difference (APDm) of 15-27% and root-mean-square-error (RMS) of 0.0021-0.0039 sr-1, whereas the Rrs(λ) uncertainty at 412 nm is the highest (APDm 47-62%, RMS 0.0027-0.0041 sr-1). The uncertainties of the aerosol optical thickness (AOT) τa, diffuse attenuation coefficient for downward irradiance at 490 nm Kd(490), concentrations of suspended particulate sediment concentration (SPM) and Chlorophyll a (Chl-a) were also quantified. It is demonstrated that with appropriate in-water algorithms specifically developed for turbid waters rather than the standard ones adopted in the operational satellite data processing chain, the uncertainties of satellite-derived properties of Kd(490), SPM, and Chl-a may decrease significantly to the level of 20-30%, which is true for the majority of the study area. This validation activity advocates for (1) the improvement of the atmosphere correction algorithms with the regional aerosol optical model, (2) switching to regional in-water algorithms over turbid coastal waters, and (3) continuous support of the dedicated in situ data collection effort for the validation task.

  9. The MODIS Rapid Response Project: Near-Real-Time Processing for Fire Monitoring and Other Applications

    NASA Astrophysics Data System (ADS)

    Descloitres, J.; Justice, C.; Sohlberg, R.; Giglio, L.; Schmaltz, J.; Seaton, J.; Davies, D.; Anyamba, A.; Hansen, M.; Carroll, M.; Sullivan, M.

    2003-12-01

    The Moderate-resolution Imaging Spectroradiometer (MODIS) instrument on board the Terra and Aqua satellites offers an unprecedented combination of daily spatial coverage, spatial resolution, and spectral characteristics. These capabilities make MODIS ideal to observe a variety of rapid events: active fires, floods, smoke transport, dust storms, severe storms, iceberg calving, and volcanic eruptions. The MODIS Rapid Response System (http://rapidfire.sci.gsfc.nasa.gov) was developed at NASA's Goddard Space Flight Center to provide a rapid response to those events, with initial emphasis on active fire detection and 250m-resolution imagery. MODIS data for most of the Earth's land surface is processed just a few hours after data acquisition. A collaboration between NASA, the University of Maryland and the U.S.D.A. Forest Service has been developed to provide fire information derived from MODIS to federal fire managers. Active fire locations in the conterminous United States are produced by the MODIS Rapid Response System and communicated to the Forest Service within a few minutes of production. The MODIS Rapid Response processing was also adapted to Direct Broadcast to reduce the product turn-around to just minutes after data acquisition regionally. MODIS active fire locations are used by the Forest Service to generate regional fire maps over the United States, updated twice daily and provided to the fire managers to help them allocate firefighting resources. Active fire locations are also distributed in near-real-time to the Global Observation of Forest Cover (G.O.F.C.) user community through a web interface integrating MODIS active fire locations and Geographic Information System (G.I.S.) datasets. The suite of MODIS rapid fire products is currently being complemented with a Smoke Index product and a Burned Area product that will represent two new key tools available to the fire community. Finally a new collaboration with the U.S.D.A. Foreign Agricultural Service was recently developed to generate near-real-time MODIS data for crop monitoring and forecasting applications. A rapid Vegetation Index product was created to that effect.

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

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

    Surface temperatures on the Greenland Ice Sheet have been studied on the ground, using automatic weather station (AWS) data from the Greenland-Climate Network (GC-Net), and from analysis of satellite sensor data. Using Advanced Very High Frequency Radiometer (AVHRR) weekly surface temperature maps, warming of the surface of the Greenland Ice Sheet has been documented from 1981 to present. We extend and refine this record using higher-resolution Moderate-Resolution Imaging Spectroradiometer (MODIS) data from March 2000 to the present. To permit changes to be observed over time, we are developing a well-characterized monthly climate-data record (CDR) of the "clear-sky" surface temperature of the Greenland Ice Sheet using data from both the Terra and Aqua satellites. We use the MODIS ice-surface temperature (IST) algorithm. Validation of the CDR consists of several facets: 1) comparisons between the Terra and Aqua IST maps; 2) comparisons between ISTs and in-situ measurements; 3) comparisons between ISTs and AWS data; and 4) comparisons of ISTs with surface temperatures derived from other satellite instruments such as the Thermal Emission and Reflection Radiometer. In this work, we focus on 1) and 2) above. Surface temperatures on the Greenland Ice Sheet have been studied on the ground, using automatic weather station (AWS) data from the Greenland-Climate Network (GC-Net), and from analysis of satellite sensor data. Using Advanced Very High Frequency Radiometer (AVHRR) weekly surface temperature maps, warming of the surface of the Greenland Ice Sheet has been documented from 1981 to present. We extend and refine this record using higher-resolution Moderate-Resolution Imaging Spectroradiometer (MODIS) data from March 2000 to the present. To permit changes to be observed over time, we are developing a well-characterized monthly climate-data record (CDR) of the "clear-sky" surface temperature of the Greenland Ice Sheet using data from both the Terra and Aqua satellites. We use the MODIS ice-surface temperature (IST) algorithm. Validation of the CDR consists of several facets: 1) comparisons between the Terra and Aqua IST maps; 2) comparisons between ISTs and in-situ measurements; 3) comparisons between ISTs and AWS data; and 4) comparisons of ISTs with surface temperatures derived from other satellite instruments such as the Thermal Emission and Reflection Radiometer. In this work, we focus on 1) and 2) above. First we provide comparisons between Terra and Aqua swath-based ISTs at approximately 14:00 Local Solar Time, reprojected to 12.5 km polar stereographic cells. Results show good correspondence when Terra and Aqua data were acquired within 2 hrs of each other. For example, for a cell centered over Summit Camp (72.58 N, 38.5 W), the average agreement between Terra and Aqua ISTs is 0.74 K (February 2003), 0.47 K (April 2003), 0.7 K (August 2003) and 0.96 K (October 2003) with the Terra ISTs being generally lower than the Aqua ISTs. More precise comparisons will be calculated using pixel data at the swath level, and correspondence between Terra and Aqua IST is expected to be closer. (Because of cloud cover and other considerations, only a few common cloud-free swaths are typically available for each month for comparison.) Additionally, previous work comparing land-surface temperatures (LSTs) from the standard MODIS LST product and in-situ surface-temperature data at Summit Camp on the Greenland Ice Sheet show that Terra MODIS LSTs are about 3 K lower than in-situ temperatures at Summit Camp, during the winter of 2008-09. This work will be repeated using both Terra and Aqua IST pixel data (in place of LST data). In conclusion, we demonstrate that the uncertainties in the CDR will be well characterized as we work through the various facets of its validation.

  11. MODIS Instrument Operation and Calibration Improvements

    NASA Technical Reports Server (NTRS)

    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.

  12. Satellite Remote Sensing of Pan-arctic Vegetation Productivity, Soil Respiration and net CO2 Exchange Using MODIS and AMSR-E Data

    NASA Astrophysics Data System (ADS)

    Nirala, M. L.; Heinsch, F. A.; Kimball, J. S.; Zhao, M.; Running, S.; Oechel, W.; McDonald, K.; Njoku, E.

    2005-05-01

    We have developed an approach for regional assessment and monitoring of land-atmosphere carbon dioxide (CO2) exchange, soil heterotrophic respiration (Rh) and vegetation productivity for arctic tundra using global satellite remote sensing at optical and microwave wavelengths. We use C- and X-band brightness temperatures from AMSR-E to extract surface wetness and temperature, and MODIS data to derive land cover, Leaf Area Index (LAI) and Net Primary Production (NPP) information. Calibration and validation activities involve comparisons between satellite remote sensing and tundra CO2 eddy flux tower and biophysical measurement networks and hydro-ecological process model simulations. We analyze spatial and temporal anomalies and environmental drivers of land-atmosphere net CO2 exchange at weekly and annual time steps. Surface soil moisture status and temperature as detected from satellite remote sensing observations are found to be major drivers spatial and temporal patterns of tundra net CO2 exchange and photosynthetic and respiration processes. We also find that satellite microwave measurements are capable of capturing seasonal variations and regional patterns in tundra soil heterotrophic respiration and CO2 exchange, while our ability to extract spatial patterns at the scale of surface heterogeneity is limited by the coarse spatial scale of the satellite remote sensing footprint. Our results also indicate that carbon cycle response to climate change is non-linear and strongly coupled to arctic surface hydrology. This work was performed at The University of Montana and Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.

  13. Fuel for the Fire: Improved Understanding of Fire Behavior in Africa Based on Partitioned Herbaceous and Woody LAI from MODIS Satellite Data

    NASA Astrophysics Data System (ADS)

    Kahiu, M. N.; Hanan, N. P.

    2014-12-01

    Fire is an important recurrent phenomenon that determines the distribution of global savanna biomes and tree cover in savanna ecosystems. Tropical savanna fires are almost exclusively ground fires, fueled by senescent herbaceous material, with crown fires being rare. Analyses of satellite-based fire activity and burned area (active fires and burn-scars) in tropical savannas reveal a close correlation with satellite-based estimates of total net primary productivity (NPP) in drier savannas, and apparent limitation by rainfall (fuel moisture) in wetter systems. However, these analyses of fire frequency and extent at continental scales ignore the different roles played by the herbaceous and woody vegetation components in promoting and/or suppressing fire ignition and spread. In this research we hypothesized that, since herbaceous vegetation provides the primary fuel, fire frequency and burn areas in African savannas and seasonal woodlands should correlate more closely with measurements of herbaceous NPP or end of season leaf area index (LAI), than with the NPP or LAI of the tree layer. Similarly, while fire patterns may correlate with patterns of total LAI and total NPP across Africa, the relationship will be confounded by variations in tree cover. Our objective is to understand how fire frequency and intensity vary with changes in herbaceous cover. To test our hypotheses we will use estimates of herbaceous and woody LAI that we have developed recently by partitioning MODIS LAI. We will explore how seasonal maximum herbaceous LAI and leaf area duration (LAD) (both potential proxies for accumulated fuel load) correlate with fire frequency in African savannas. We will demonstrate the MODIS LAI partitioning methodology, and present results on the divergent relationships between African savanna fires and total LAI, herbaceous LAI and herbaceous LAD.

  14. Evaluation of hydrological balance in the eastern Amazon using a terrestrial ecosystem model, and satellite-based evapotranspiration (MODIS) and terrestrial water storage (GRACE)

    NASA Astrophysics Data System (ADS)

    Panday, P. K.; Coe, M. T.; Macedo, M.; Beck, P.

    2013-12-01

    High historical deforestation rates and a rapidly changing agricultural landscape may dramatically alter the energy and water balance of the eastern Amazon basin. Understanding the surface water dynamics and hydrological balance of the region is critical for accurately assessing the historical and potential future impacts of deforestation, land-use change, and land management practices. We examine the water balance of the Xingu river basin by combining the IBIS (Integrated Biosphere Simulator) terrestrial ecosystem model with satellite-based models of evapotranspiration (MOD16) and terrestrial water storage (GRACE). IBIS simulations were forced with prescribed climate to produce modeled evapotranspiration and runoff, which were then compared with MODIS evapotranspiration and observed discharge at Altamira (PA, Brazil). Results from both satellite observations and model simulations support earlier studies demonstrating that dry-season evapotranspiration is higher than wet-season evapotranspiration in the wetter forests of the northern Xingu basin, while the contrary is true in the seasonally dry forests of the southern Xingu. Seasonal variation in modeled soil water storage agrees with the GRACE measurements in both timing and magnitude. Soil moisture anomalies averaged over the Xingu basin suggest that annual changes in soil water storage account for a large part of the interannual variation in observed discharge. Field measurements of discharge and soil moisture in the southern Xingu also support the findings that changes in soil water storage drive inter-annual variations in river discharge. Figure 1. Comparison of observed discharge at Altamira (Pará, Brazil) against MODIS- derived P-E (PCRU-MODISET), IBIS simulated discharge, IBIS (PCRU-ETIBIS), and IBIS (PCRU-ETIBIS- Δ Soil moisture IBIS). The bottom panel shows annual basin precipitation from Climatic Research Unit (CRU) climatological data for the 2000-2008 period

  15. Time-series MODIS satellite and in-situ data for spatio-temporal distribution of aerosol pollution assessment over Bucharest metropolitan area

    NASA Astrophysics Data System (ADS)

    Zoran, Maria A.; Savastru, Roxana S.; Savastru, Dan M.

    2015-10-01

    With the increasing industrialization and urbanization, especially in the metropolis regions, aerosol pollution has highly negative effects on environment. Urbanization is responsible of three major changes that may have impact on the urban atmosphere: replacement of the natural surfaces with buildings and impermeable pavements, heat of anthropogenic origin and air pollution. The importance of aerosols for radiative and atmospheric chemical processes is widely recognized. They can scatter and/or absorb solar radiation leading to changes of the radiation budget. Also, the so-called indirect effect of aerosols describes the cloud-aerosol interactions, which can modify the chemical and physical processes in the atmosphere. Their high spatial variability and short lifetime make spaceborne sensors especially well suited for their observation. Remote sensing is a key application in global-change science and urban climatology. Since the launch of the MODerate resolution Imaging Spectroradiometer (MODIS) there is detailed global aerosol information available, both over land and oceans The aerosol parameters can be measured directly in situ or derived from satellite remote sensing observations. All these methods are important and complementary. The objective of this work was to document the seasonal and inter-annual patterns of the aerosol pollution particulate matter in two size fractions (PM10 and PM2.5) loading and air quality index (AQI) over Bucharest metropolitan area in Romania based on in-situ and MODIS (Terra-Moderate Resolution Imaging Spectoradiometer) satellite time series data over 2010-2012 period. Accurate information of urban air pollution is required for environmental and health policy, but also to act as a basis for designing and stratifying future monitoring networks.

  16. Monitoring AVHRR-MODIS-VIIRS radiometrie consistency using MICROS online near-real time system

    NASA Astrophysics Data System (ADS)

    Liang, XingMing; Ignatov, Alexander; Saha, Korak

    2013-05-01

    The Visible Infrared Imaging Radiometer Suite (VIIRS) onboard the Suomi National Polar Partnership (S-NPP) and the Joint Polar Satellite System (JPSS) builds upon heritage sensors, Advanced Very High Resolution Radiometer (AVHRR) and Moderate-Resolution Imaging Spectroradiometer (MODIS). The evaluation of AVHRR, MODIS and VIIRS radiometric stability and consistency is needed to ensure continuity of derived data products, including Sea Surface Temperatures (SST). Monitoring of IR Clear-Sky Radiances over Oceans for SST (MICROS; www.star.nesdis.noaa.gov/sod/sst/micros) near-real time web-based system was developed at NESDIS, to monitor model minus observation (M-O) biases in clear-sky ocean brightness temperatures (BT). Double differences (DD) were also employed to evaluate various sensors for consistency. Initially implemented in July 2008 with data from several AVHRRs onboard NOAA-16, -17, -18, -19 and Metop-A, it was extended in January 2012 to include AVHRR-like bands 3.7, 11, and 12μm from Terra and Aqua MODIS, and S-NPP VIIRS. This paper discusses initial results of AVHRR-MODIS-VIIRS cross-platform consistency using MICROS DDs. Work is underway to understand and minimize the observed differences, through collaboration with Sensor Calibration and Community Radiative Transfer Model (CRTM) Teams.

  17. Status of the MODIS Level 1B Algorithms and Calibration Tables

    NASA Technical Reports Server (NTRS)

    Xiong, X; Salomonson, V V; Kuyper, J; Tan, L; Chiang, K; Sun, J; Barnes, W L

    2005-01-01

    The Moderate Resolution Imaging Spectroradiometer (MODIS) makes observations using 36 spectral bands with wavelengths from 0.41 to 14.4 m and nadir spatial resolutions of 0.25km, 0.5km, and 1km. It is currently operating onboard the NASA Earth Observing System (EOS) Terra and Aqua satellites, launched in December 1999 and May 2002, respectively. The MODIS Level 1B (L1B) program converts the sensor's on-orbit responses in digital numbers to radiometrically calibrated and geo-located data products for the duration of each mission. Its primary data products are top of the atmosphere (TOA) reflectance factors for the sensor's reflective solar bands (RSB) and TOA spectral radiances for the thermal emissive bands (TEB). The L1B algorithms perform the TEB calibration on a scan-by-scan basis using the sensor's response to the on-board blackbody (BB) and other parameters which are stored in Lookup Tables (LUTs). The RSB calibration coefficients are processed offline and regularly updated through LUTs. In this paper we provide a brief description of the MODIS L1B calibration algorithms and associated LUTs with emphasis on their recent improvements and updates developed for the MODIS collection 5 processing. We will also discuss sensor on-orbit calibration and performance issues that are critical to maintaining L1B data product quality, such as changes in the sensor's response versus scan-angle.

  18. Adjustments to the MODIS Terra Radiometric Calibration and Polarization Sensitivity in the 2010 Reprocessing

    NASA Technical Reports Server (NTRS)

    Meister, Gerhard; Franz, Bryan A.

    2011-01-01

    The Moderate-Resolution Imaging Spectroradiometer (MODIS) on NASA s Earth Observing System (EOS) satellite Terra provides global coverage of top-of-atmosphere (TOA) radiances that have been successfully used for terrestrial and atmospheric research. The MODIS Terra ocean color products, however, have been compromised by an inadequate radiometric calibration at the short wavelengths. The Ocean Biology Processing Group (OBPG) at NASA has derived radiometric corrections using ocean color products from the SeaWiFS sensor as truth fields. In the R2010.0 reprocessing, these corrections have been applied to the whole mission life span of 10 years. This paper presents the corrections to the radiometric gains and to the instrument polarization sensitivity, demonstrates the improvement to the Terra ocean color products, and discusses issues that need further investigation. Although the global averages of MODIS Terra ocean color products are now in excellent agreement with those of SeaWiFS and MODIS Aqua, and image quality has been significantly improved, the large corrections applied to the radiometric calibration and polarization sensitivity require additional caution when using the data.

  19. Integrating TRMM and MODIS satellite with socio-economic vulnerability for monitoring drought risk over a tropical region of India

    NASA Astrophysics Data System (ADS)

    Yaduvanshi, Aradhana; Srivastava, Prashant K.; Pandey, A. C.

    Drought is a recurring feature of the climate, responsible for social and economic losses in India. In the present work, attempts were made to estimate the drought hazard and risk using spatial and temporal datasets of Tropical Rainfall Measuring Mission (TRMM) and Moderate Resolution Imaging Spectroradiometer (MODIS) in integration with socio-economic vulnerability. The TRMM rainfall was taken into account for trend analysis and Standardized Precipitation Index (SPI) estimation, with aim to investigate the changes in rainfall and deducing its pattern over the area. The SPI and average rainfall data derived from TRMM were interpolated to obtain the spatial and temporal pattern over the entire South Bihar of India, while the MODIS datasets were used to derive the Normalized Difference Vegetation Index (NDVI) deviation in the area. The Geographical Information System (GIS) is taken into account to integrate the drought vulnerability and hazard, in order to estimate the drought risk over entire South Bihar. The results indicated that approximately 36.90% area is facing high to very high drought risk over north-eastern and western part of South Bihar and need conservation measurements to combat this disaster.

  20. The Use of MODIS Instrument on the EOS-Terra Satellite to Assess the Impact of Aerosol on Climate

    NASA Technical Reports Server (NTRS)

    Kaufman, Y.; Einaudi, Franco (Technical Monitor)

    2001-01-01

    Terra will derive the aerosol optical thickness and properties. The aerosol properties can be used to distinguish between natural and human-made aerosol. In the polar orbit Terra will measure aerosol only once a day, around 10:30 am. How will we use this information to study the global radiative impacts of aerosol on climate? We shall present a strategy to address this problem. It includes the following steps: 1) From the Terra aerosol optical thickness and size distribution model we derive the effect of aerosol on reflection of solar radiation at the top of the atmosphere. In a sensitivity study we show that the effect of aerosol on solar fluxes can be derived 10 times more accurately from the MODIS data than derivation of the optical thickness itself. Applications to data over several regions will be given. 2) Using 1/2 million AERONET global data of aerosol spectral optical thickness we show that the aerosol optical thickness and properties during the Terra 10:30 pass are equivalent to the daily average. Due to the aerosol lifetime of several days measurements at this time of the day are enough to assess the daily impact of aerosol on radiation. 3) Aerosol impact on the top of the atmosphere is only part of the climate question. The INDOEX experiment showed that addressing the impact of aerosol on climate, requires also measurements of the aerosol forcing at the surface. This can be done by a combination of measurements of MODIS and AERONET data.

  1. The MODIS Vegetation Canopy Water Content product

    NASA Astrophysics Data System (ADS)

    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; improve irrigation scheduling by reducing over-watering and under-watering. These estimates will also allow researchers to identify wildfire behavior/risk: drives ignition probability and burning efficiency; to be used as an indicator of soil moisture and Leaf Area Index.

  2. Tracking Terra MODIS on-orbit polarization sensitivity using pseudo-invariant desert sites

    NASA Astrophysics Data System (ADS)

    Wu, Aisheng; Geng, Xu; Wald, Andrew; Angal, Amit; Xiong, Xiaoxiong

    2015-10-01

    The Moderate-Resolution Imaging Spectroradiometer (MODIS) is currently flying on NASA's Earth Observing System (EOS) Terra and Aqua satellites, launched in 1999 and 2002, respectively. MODIS reflective solar bands (RSB) in the visible wavelength range are known to be sensitive to polarized light based on prelaunch polarization sensitivity tests. The polarization impact is dependent on scan angle and mirror side. After about five years of on-orbit operation, it is found that a few shortest-wavelength bands of Terra MODIS show increased polarization sensitivity. In this study, we examine the impact of polarization on measured top-of-atmosphere (TOA) reflectances over pseudo-invariant desert sites. The standard polarization correction equation is used in combination with simulated at-sensor radiances by the Second Simulation of a Satellite Signal in the Solar Spectrum (6SV), Vector Radiative Transfer Code. Key Mueller matrix elements describing the polarization and gain correction of these bands are derived over the mission lifetime. Results indicate that the polarization sensitivity increases with scan mirror's angle of incidence (AOI) and relatively large impact is observed from mirror side 2. At the end of 2009, it reaches a peak at approximately 30% at 0.41 μm and stabilizes since then.

  3. Estimating emissions from agricultural fires in the North China Plain based on MODIS fire radiative power

    NASA Astrophysics Data System (ADS)

    Liu, Mingxu; Song, Yu; Yao, Huan; Kang, Yaning; Li, Mengmeng; Huang, Xin; Hu, Min

    2015-07-01

    Crop-residue burning plays an important role in regional air quality and global climate change. The North China Plain, the largest winter wheat production district in China, experiences extensive crop fires during harvest seasons. Traditional methods to estimate emissions from crop fires depend strongly on burned area, biomass density, combustion efficiency, and emission factor. However, the uncertainty of burned area derived from satellites can be very large because the agricultural fires in China have small sizes and short duration. Using fire radiative power (FRP) to estimate emissions depends on a few numbers of parameters and has been applied in recent researches. In our study, emissions from crop burning in fields in the North China Plain were estimated using MODIS FRP derived from the Terra and Aqua satellites. The time-integrated FRP (i.e., fire radiative energy, FRE) in per fire pixel and fire counts are important factors in the estimation. The estimated results showed that high fire emissions were in 2005-2007 and 2012, while low emissions were in the fire years 2003 and 2004. Our estimated emissions were close to a previous study with an agricultural statistical approach, but significantly higher than emissions derived from the MODIS burned area product and Global Fire Emissions Database, respectively. The emission uncertainties in our study mainly originated from MODIS pixel resolution, emission factors, FRP measurements, and FRP parameterization.

  4. Initial approach in biomass burning aerosol transport tracking with CALIPSO and MODIS satellites, sunphotometer, and a backscatter lidar system in Brazil

    NASA Astrophysics Data System (ADS)

    Landulfo, E.; Lopes, F. J. S.

    2009-09-01

    Nowadays there is an increasing concern about the direct and indirect influence of the aerosols in the Earth's radiative budget. Aerosols from biomass burning activities have been identified as a significant radiative forcing agent. A significant concentration quantity of aerosol particles observed in the atmosphere can be associated with intense anthropogenic biomass burning activity. The CALIPSO satellite and ground-based Lidar systems are indispensable to provide the vertical structure and optical properties of aerosol and clouds on global and local scale, respectively. The Brazilian mid-western region is one of the biggest producers of biomass burning in the whole continent. Aerosols from biomass burning can be transported to distances of hundreds or thousands of kilometers. It has been developed a computational routine to map the CALIPSO overpasses over the whole country in order to retrieve the total coverage taking special attention in the Brazilian AERONET sites. In this context, the measured data from AERONET, CALIPSO and MODIS Satellite and the MSP-Lidar system from Instituto de Pesquisas Energéticas e Nucleares (IPEN) can be used to map the aerosols biomass burning plumes transported from the mid-western to the southeastern region. In total 5 sites were chosen spanning from 0 to 23 South latitude and 46 to 60 West in longitude in coverage during 2007 and we were able to identify such transports during the months of August and September.

  5. Exploring New Methods of Displaying Bit-Level Quality and Other Flags for MODIS Data

    NASA Technical Reports Server (NTRS)

    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.

  6. Evaluating the impact of above-cloud aerosols on cloud optical depth retrievals from MODIS

    NASA Astrophysics Data System (ADS)

    Alfaro, Ricardo

    Using two different operational Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) cloud optical depth (COD) retrievals (visible and shortwave infrared), the impacts of above-cloud absorbing aerosols on the standard COD retrievals are evaluated. For fine-mode aerosol particles, aerosol optical depth (AOD) values diminish sharply from the visible to the shortwave infrared channels. Thus, a suppressed above-cloud particle radiance aliasing effect occurs for COD retrievals using shortwave infrared channels. Aerosol Index (AI) from the spatially and temporally collocated Ozone Monitoring Instrument (OMI) are used to identify above-cloud aerosol particle loading over the southern Atlantic Ocean, including both smoke and dust from the African sub-continent. MODIS and OMI Collocated Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) data are used to constrain cloud phase and provide contextual above-cloud AOD values. The frequency of occurrence of above-cloud aerosols is depicted on a global scale for the spring and summer seasons from OMI and CALIOP, thus indicating the significance of the problem. Seasonal frequencies for smoke-over-cloud off the southwestern Africa coastline reach 20--50% in boreal summer. We find a corresponding low COD bias of 10--20% for standard MODIS COD retrievals when averaged OMI AI are larger than 1.0. No such bias is found over the Saharan dust outflow region off northern Africa, since both MODIS visible and shortwave in channels are vulnerable to dust particle aliasing, and thus a COD impact cannot be isolated with this method. A similar result is found for a smaller domain, in the Gulf of Tonkin region, from smoke advection over marine stratocumulus clouds and outflow into the northern South China Sea in spring. This study shows the necessity of accounting for the above-cloud aerosol events for future studies using standard MODIS cloud products in biomass burning outflow regions, through the use of collocated OMI AI and supplementary MODIS shortwave infrared COD products.

  7. ANALYSIS OF YEAR 2002 SEASONAL FOREST DYNAMICS USING TIME SERIES IN SITU LAI MEASUREMENTS AND MODIS LAI SATELLITE PRODUCTS

    EPA Science Inventory

    Multitemporal satellite images are the standard basis for regional-scale land-cover (LC) change detection. However, embedded in the data are the confounding effects of vegetation dynamics (phenology). As photosynthetic vegetation progresses through its annual cycle, the spectral ...

  8. Interannual variability and short-term trends in the MODIS aerosol record

    NASA Astrophysics Data System (ADS)

    Remer, L. A.; Koren, I.; Levy, R. C.; Tanre, D.; Karnieli, A.; Longo, K.; Martins, J. V.; Mattoo, S.; Kleidman, R. G.; Holben, B. N.

    2008-12-01

    The MODerate resolution Imaging Spectroradiometer (MODIS) aboard the Terra and Aqua satellites has been producing an aerosol product since early 2000. These data now provide us with 8 full years of near global aerosol observations. During this period we have seen the MODIS aerosol optical depth decrease over much of the northern hemisphere, and driven by tropical biomass burning increase over much of the southern hemisphere. The short term trends are seen in both the Terra and Aqua records, and local trends are verified by trends in long-term AERONET stations. This confirmation by complementary observing systems points to a robustness in the results. The year to year variation and short term trends are highly regionally specific. We examine recent interannual variation in biomass burning in the Amazon showing how the overall increase in smoke production over the past 8 years can be reversed due to a combination of wetter conditions and changes in cultural practices. We also show how a decrease in sulfur emissions in eastern Europe can affect the aerosol optical depth both locally and at a down wind receptor site in Israel. Our experience over the past 8 years shows us the complexity of the anthropogenic influence on aerosols, and how that influence is both regionally specific and a moving target. The results make a strong argument for continued high quality monitoring of the global aerosol system from ground-based and space-based sensors.

  9. Spatiotemporal distribution of Chl a in the Gulf of Mexico based on MODIS geophysical products

    NASA Astrophysics Data System (ADS)

    Chintalapudi, S.; Xie, H.; Sharif, H. O.

    2010-12-01

    This study uses the Moderate Resolution Imaging Spectro radiometer (MODIS) Aqua level-3 satellite imagery data to examine the seasonal phytoplankton blooms in the Gulf of Mexico (GOM) and to assess the relationships between chlorophyll a (chl a) concentrations and river discharge, hurricanes, winds, nutrient loads, oil spills, and population. Daily MODIS Aqua 8-day composite level-3 images are used from 2002 to 2010. Initial results show that chl a concentration is higher during September to March of a year, with maximum at the Mississippi-Atchafalaya river deltas. A strong positive correlation is found between stream flow and chl a at the major river estuaries for most of the years. Hurricane and tropical storm events are found to play an important role for chl a bloom occurred in the period of autumn to early winter seasons, since they bring nutrients and dissolved organic matter to the surface from the bottom layers of ocean. For example, Isidore occurred on Sep 20th leads to the largest mean chl a concentrations of the year 2002. During the spring season, maximum chl a concentrations are mostly due to higher fresh water discharge from major rivers. High population leads to the high waste water that can contribute more nutrients to the rivers. Sewage and Industrial supply increases around 10 to 20 percent of the total N and approximately 40 percent of the total P contribution in the Mississippi river (Issues in Ecology, 2000). These increases in nutrient concentrations also increase the algal blooms at the estuaries.

  10. In Search for Thermal Precursors to Earthquakes in California Using MODIS Land Surface Temperature Data

    NASA Astrophysics Data System (ADS)

    Adams, D. A.; Eneva, M.

    2007-12-01

    We test claims that earthquakes are preceded by thermal anomalies by analyzing daily nighttime land surface temperatures (LSTs) derived from data collected by the MODIS (Moderate Resolution Imaging Spectroradiometer) instruments mounted on the Terra and Aqua satellites. Terra precedes Aqua by ~3 hours, so the LST difference between the two satellites provides an estimate of nighttime cooling/warming rates. The MODIS LST data used cover the period between 2000 and 2006 and are with ~1 km spatial resolution. They cover a 10°x10° tile including most of California, parts of neighboring Nevada and Arizona, and northern Mexico. Our focus is on quantifying various factors influencing the background variability of LSTs and estimating the uniqueness and statistical significance of any apparent LST anomalies. For this purpose, the LSTs and their Aqua-Terra differences are used to calculate parameters similar to the Robust Estimator of Thermal Infrared Anomalies (RETIRA) index, first described by Tramutoli (1998) and subsequently reported to show anomalously high values preceding a number of earthquakes (e.g., Tramutoli et al., 2005; Corrado et al., 2005; Genzano et al, 2007). We develop the RETIRA concept further in order to account better for meteorological and other effects on the LSTs. In particular, we quantify cloud edge effects and the effects of topography. The RETIRA index is computed for Terra LSTs, Aqua LSTs, and Aqua-Terra LST differences. We examine the relationship between M>4.5 earthquakes and anomalous RETIRA by generating movies of RETIRA time evolution. We also compare and test for statistical significance of the differences among four types of combined time periods - pre-seismic, during seismic clusters, post-seismic and seismically quiet periods. Although some statistically significant differences are established, they do not involve uniquely the pre-seismic periods and anomalies appear too ubiquitous during all types of periods to be useful for earthquake prediction. We will be further testing smaller areas around "hot spots" (Holliday and Rundle, 2005) and past earthquakes in California.

  11. MODIS On-Board Blackbody Function and Performance

    NASA Technical Reports Server (NTRS)

    Xiaoxiong, Xiong; Wenny, Brian N.; Wu, Aisheng; Barnes, William

    2009-01-01

    Two MODIS instruments are currently in orbit, making continuous global observations in visible to long-wave infrared wavelengths. Compared to heritage sensors, MODIS was built with an advanced set of on-board calibrators, providing sensor radiometric, spectral, and spatial calibration and characterization during on-orbit operation. For the thermal emissive bands (TEB) with wavelengths from 3.7 m to 14.4 m, a v-grooved blackbody (BB) is used as the primary calibration source. The BB temperature is accurately measured each scan (1.47s) using a set of 12 temperature sensors traceable to NIST temperature standards. The onboard BB is nominally operated at a fixed temperature, 290K for Terra MODIS and 285K for Aqua MODIS, to compute the TEB linear calibration coefficients. Periodically, its temperature is varied from 270K (instrument ambient) to 315K in order to evaluate and update the nonlinear calibration coefficients. This paper describes MODIS on-board BB functions with emphasis on on-orbit operation and performance. It examines the BB temperature uncertainties under different operational conditions and their impact on TEB calibration and data product quality. The temperature uniformity of the BB is also evaluated using TEB detector responses at different operating temperatures. On-orbit results demonstrate excellent short-term and long-term stability for both the Terra and Aqua MODIS on-board BB. The on-orbit BB temperature uncertainty is estimated to be 10mK for Terra MODIS at 290K and 5mK for Aqua MODIS at 285K, thus meeting the TEB design specifications. In addition, there has been no measurable BB temperature drift over the entire mission of both Terra and Aqua MODIS.

  12. Monitoring vegetation recovery in fire-affected areas using temporal profiles of spectral signal from time series MODIS and LANDSAT satellite images

    NASA Astrophysics Data System (ADS)

    Georgopoulou, Danai; Koutsias, Nikos

    2015-04-01

    Vegetation phenology is an important element of vegetation characteristics that can be useful in vegetation monitoring especially when satellite remote sensing observations are used. In that sense temporal profiles extracted from spectral signal of time series MODIS and LANDSAT satellite images can be used to characterize vegetation phenology and thus to be helpful for monitoring vegetation recovery in fire-affected areas. The aim of this study is to explore the vegetation recovery pattern of the catastrophic wildfires that occurred in Peloponnisos, southern Greece, in 2007. These fires caused the loss of 67 lives and were recognized as the most extreme natural disaster in the country's recent history. Satellite remote sensing data from MODIS and LANDSAT satellites in the period from 2000 to 2014 were acquired and processed to extract the temporal profiles of the spectral signal for selected areas within the fire-affected areas. This dataset and time period analyzed together with the time that these fires occurred gave the opportunity to create temporal profiles seven years before and seven years after the fire. The different scale of the data used gave us the chance to understand how vegetation phenology and therefore the recovery patterns are influenced by the spatial resolution of the satellite data used. Different metrics linked to key phenological events have been created and used to assess vegetation recovery in the fire-affected areas. Our analysis was focused in the main land cover types that were mostly affected by the 2007 wildland fires. Based on CORINE land-cover maps these were agricultural lands highly interspersed with large areas of natural vegetation followed by sclerophyllous vegetation, transitional woodland shrubs, complex cultivation patterns and olive groves. Apart of the use of the original spectral data we estimated and used vegetation indices commonly found in vegetation studies as well as in burned area mapping studies. In this study we explore the strength and the use of these time series satellite data to characterize vegetation phenology as an a aid to monitor vegetation recovery in fire affected-areas. In a recent study we found that the original spectral channels, based on which these indices are estimated, are sensitive to external vegetation parameters such as the spectral reflectance of the background soil. In such cases, the influence of the soil in the reflectance values is different in the various spectral regions depending on its type. The use of such indices is also justified according to a recent study on the sensitivity of spectral reflectance values to different burn and vegetation ratios, who concluded that the Near Infrared (NIR) and Short-Wave Infrared (SWIR) are the most important channels to estimate the percentage of burned area, whereas the NIR and red channels are the most important to estimate the percentage of vegetation in fire-affected areas. Additionally, it has been found that semi-burned classes are spectrally more consistent to their different fractions of scorched and non-scorched vegetation, than the original spectral channels based on which these indices are estimated.

  13. Analysis of Co-Located MODIS and CALIPSO Observations Near Clouds

    NASA Technical Reports Server (NTRS)

    Varnai, Tamas; Marshak, Alexander

    2011-01-01

    The purpose of this paper is to help researchers combine data from different satellites and thus gain new insights into two critical yet poorly understood aspects of anthropogenic climate change, aerosol-cloud interactions and aerosol radiative effects, For this, the paper explores whether cloud information from the Aqua satellite's MODIS instrument can help characterize systematic aerosol changes near clouds by refining earlier perceptions of these changes that were based on the CALIPSO satellite's CALIOP instrument. Similar to a radar but using visible and ncar-infrared light, CALIOP sends out laser pulses and provides aerosol and cloud information along a single line that tracks the satellite orbit by measuring the reflection of its pulses. In contrast, MODIS takes images of reflected sunlight and emitted infrared radiation at several wavelengths, and covers wide areas around the satellite track. This paper analyzes a year-long global dataset covering all ice-free oceans, and finds that MODIS can greatly help the interpretation of CALIOP observations, especially by detecting clouds that lie outside the line observed by CALlPSO. The paper also finds that complications such as differences in view direction or clouds drifting in the 72 seconds that elapse between MODIS and CALIOP observations have only a minor impact. The study also finds that MODIS data helps refine but does not qualitatively alter perceptions of the systematic aerosol changes that were detected in earlier studies using only CALIOP data. It then proposes a statistical approach to account for clouds lying outside the CALIOP track even when MODIS cannot as reliably detect low clouds, for example at night or over ice. Finally, the paper finds that, because of variations in cloud amount and type, the typical distance to clouds in maritime clear areas varies with season and location. The overall median distance to clouds in maritime clear areas around 4-5 km. The fact that half of all clear areas is closer than 5 km to clouds implies that pronounced near-cloud changes in aerosol properties have significant implications for overall clear-sky characteristics, including the radiative impact of aerosols.

  14. Clear-Sky Narrowband Albedo Datasets Derived from Modis Data

    NASA Astrophysics Data System (ADS)

    Chen, Y.; Minnis, P.; Sun-Mack, S.; Arduini, R. F.; Hong, G.

    2013-12-01

    Satellite remote sensing of clouds requires an accurate estimate of the clear-sky radiances for a given scene to detect clouds and aerosols and to retrieve their microphysical properties. Knowing the spatial and angular variability of clear-sky albedo is essential for predicting the clear-sky radiance at solar wavelengths. The Clouds and the Earth's Radiant Energy System (CERES) Project uses the near-infrared (NIR; 1.24, 1.6 or 2.13 μm) and visible (VIS; 0.63 μm) channels available on the Terra and Aqua Moderate Resolution Imaging Spectroradiometers (MODIS) to help identify clouds and retrieve their properties. Generally, clear-sky albedo for a given surface type is determined for conditions when the vegetation is either thriving or dormant and free of snow. The clear-sky albedos are derived using a radiative transfer parameterization of the impact of the atmosphere, including aerosols, on the observed reflectances. This paper presents the method of generating monthly clear-sky overhead albedo maps for both snow-free and snow-covered surfaces of these channels using one year of MODIS (Moderate Resolution Imaging Spectroradiometer) CERES products. Maps of 1.24 and 1.6 μm are being used as the background to help retrieve cloud properties (e.g., effective particle size, optical depth) in CERES cloud retrievals in both snow-free and snow-covered conditions.

  15. Global Distributions of Mineral Dust Properties from SeaWiFS and MODIS: From Sources to Sinks

    NASA Technical Reports Server (NTRS)

    Hsu, N. Christina; Bettenhausen, C.; Sayer, A.

    2011-01-01

    The impact of natural and anthropogenic sources of mineral dust has gained increasing attention from scientific communities in recent years. Indeed, these airborne dust particles, once lifted over the source regions, can be transported out of the boundary layer into the free troposphere and can travel thousands of kilometers across the oceans resulting in important biogeochemical impacts on the ecosystem. Due to the relatively short lifetime (a few hours to about a week), the distributions of these mineral dust particles vary extensively in both space and time. Consequently, satellite observations are needed over both source and sink regions for continuous temporal and spatial sampling of aerosol properties. With the launch of SeaWiFS in 1997, Terra/MODIS in 1999, and Aqua/MODIS in 2002, high quality comprehensive aerosol climatology is becoming feasible for the first time. As a result of these unprecedented satellite data records, studies of the radiative and biogeochemical effects due to dust aerosols are now possible. In this study, we will show the comparisons of satellite retrieved aerosol optical thickness using Deep Blue algorithm with data from AERONET sunphotometers over desert and semi-desert regions as well as vegetated areas. Our results indicate reasonable agreements between these two. These new satellite products will allow scientists to determine quantitatively the aerosol properties near sources using high spatial resolution measurements from Sea WiFS and MODIS-like instruments. The multiyear satellite measurements since 1997 from Sea WiFS will be compared with those retrieved from MODIS and MISR, and will be utilized to investigate the interannual variability of source, pathway, and dust loading associated with the dust outbreaks over the entire globe. Finally, the trends observed over the last decade based upon the SeaWiFS time series in the amounts of tropospheric aerosols due to natural and anthropogenic sources (such as changes in the frequency of dust storms) will be discussed.

  16. A Web Service Tool (SOAR) for the Dynamic Generation of L1 Grids of Coincident AIRS, AMSU and MODIS Satellite Sounding Radiance Data for Climate Studies

    NASA Astrophysics Data System (ADS)

    Halem, M.; Yesha, Y.; Tilmes, C.; Chapman, D.; Goldberg, M.; Zhou, L.

    2007-05-01

    Three decades of Earth remote sensing from NASA, NOAA and DOD operational and research satellites carrying successive generations of improved atmospheric sounder instruments have resulted in petabytes of radiance data with varying spatial and spectral resolutions being stored at different data archives in various data formats by the respective agencies. This evolution of sounders and the diversities of these archived data sets have led to data processing obstacles limiting the science community from readily accessing and analyzing such long-term climate data records. We address this problem by the development of a web based Service Oriented Atmospheric Radiance (SOAR) system built on the SOA paradigm that makes it practical for the science community to dynamically access, manipulate and generate long term records of L1 pre-gridded sounding radiances of coincident multi-sensor data for regions specified according to user chosen criteria. SOAR employs a modification of the standard Client Server interactions that allows users to represent themselves directly to the Process Server through their own web browsers. The browser uses AJAX to request Javascript libraries and DHTML interfaces that define the possible client interactions and communicates the SOAP messages to the Process server allowing for dynamic web dialogs with the user to take place on the fly. The Process Server is also connected to an underlying high performance compute cluster and storage system which provides much of the data processing capabilities required to service the client requests. The compute cluster employs optical communications to NOAA and NASA for accessing the data and under the governance of the Process Server invokes algorithms for on-demand spatial, temporal, and spectral gridding. Scientists can choose from a variety of statistical averaging techniques for compositing satellite observed sounder radiances from the AIRS, AMSU or MODIS instruments to form spatial-temporal grids for their respective studies. A range of scientific visualization and animation services are also provided for viewing the results of the user specified service requests. Results of gridding, visualization and animating services for compositing and convolving the AIRS and MODIS spectral sounding radiances will be presented. In addition, demonstrations of SOAR on demand visualizations and animations for subsetting multi-year high-resolution multi-instrument pre-gridded radiance fields will be presented.

  17. Comparisons of savanna functioning, phenology, and disturbance in Brazil and Australia using MODIS and TRMM satellite data

    NASA Astrophysics Data System (ADS)

    Ratana, P.; Huete, A. R.; Ferreira, L. G.; Ma, X.; Restrepo-Coupe, N.

    2013-12-01

    The savanna biome is comprised of complex vegetation structures with multifunctional herbaceous (grass) and woody (tree- shrub) layers, each responding uniquely to different environmental controls. Globally, their rich biodiversity is under pressure from land conversion to crops, pastures, grazing activities, and fire. A better understanding of their vegetation functioning, seasonal dynamics and phenology, and responses to climate, disturbance, and management practices is needed. This study focuses on two contrasting tropical savanna regions; the Brazilian cerrado and the savanna biome in northern Australia. The cerrado has open to closed woodlands and is the most intensively converted (pastures), whereas the Australian savanna is relatively undisturbed and encompasses both wet and dry savanna classes along an ecological rainfall gradient. We investigated these environmental and management drivers on savanna class seasonal functioning patterns using the Moderate Resolution Imaging Spectroradiometer (MODIS) vegetation index (VI) time series from 2000 to 2013 combined with rainfall data over the same time period from the Tropical Rainfall Monitoring Mission (TRMM). We found unique seasonal/ phenological vegetation response patterns with varying tree- grass ratios, rainfall seasonal distribution, and magnitude of land conversion and management. Temporal VI profiles of both regions depicted high seasonal contrasts in vegetation production over the pronounced dry and wet seasons, and seasonal amplitude variations varied negatively with the presence and extent of woody tree cover. We found pronounced shifts in seasonal/ phenology patterns in both Brazilian cerrado and Australian savanna induced by land conversion. Lastly, sensitivity to climate variability was greatest in the areas dominated with low tree-grass ratios.

  18. Evaluating the Impact of Smoke Particle Absorption on Passive Satellite Cloud Optical Depth Retrievals

    NASA Astrophysics Data System (ADS)

    Alfaro-Contreras, R.; Zhang, J.; Reid, J. S.; Campbell, J. R.

    2013-12-01

    Absorbing aerosol particles, when lifted above clouds, can perturb top-of-atmosphere radiation radiances measured by passive satellite sensors through the absorption of reflected solar energy. This scenario, if not properly screened, impacts cloud physical retrievals, like cloud optical depth (COD), conducted using radiances/channels in the visible spectrum. We describe observations of smoke particle presence above cloud off the southwest coast of Africa, using spatially and temporally collocated Aqua Moderate Resolution Imaging Spectroradiometer (AQUA MODIS), Ozone Monitoring Instrument (OMI) and Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) measurements. Results from this study indicate that above cloud aerosol episodes happen rather frequent in the smoke outflow region during the Northern Hemisphere summer where above cloud aerosol plumes introduce a significant bias to MODIS COD retrievals in the visible spectrum. This suggests that individual COD retrievals as well as COD climatology from MODIS can be affected over the smoke outflow region by above cloud aerosol contamination and thus showing the need to account for the presence of above cloud absorbing aerosols in the MODIS visible COD retrievals.

  19. Comparison between wildfire emissions in the Pacific Northwest calculated using the BLUESKY air quality framework and calculated using MODIS fire energy satellite data

    NASA Astrophysics Data System (ADS)

    Leung, F. T.; Rengel, A.; Vaughan, J. K.

    2012-12-01

    The frequency and intensity of wildfires are expected to increase in the Western United States as a result of climate change. Such changes may have a profound effect on the concentration of airborne pollutants at downwind locations. Of particular concern are the potential changes in surface ozone and particulate matter, elevated concentrations of which have deleterious effects on human health. Regional air quality models are an important tool for the atmospheric scientists and for the air quality managers. In these models, accurate estimates of emissions of airborne pollutants from fires are important during the summer fire season, and will become increasingly important. However, there are significant problems in obtaining accurate emissions estimates stemming from inaccurate and missing high resolution data about and models of fuels, fire behavior and meteorological factors. A complementary method of estimating fire emissions, which makes use of satellite observations of fire radiative energy and smoke associated with fires, has been used to some success. In this study, we compare the fire emissions calculated using the implementation of the Bluesky framework in the AIRPACT-4 regional air quality system for the Pacific Northwest United States, with fire emissions calculated using MODIS Fire Radiative Power data, for specific fires. Comparison of the differences between emissions estimates for specific fires may provide insight on effect of various geographical and meteorological factors on them.

  20. Monitoring the state of vegetation in Hungary using 15 years long MODIS Data

    NASA Astrophysics Data System (ADS)

    Kern, Anikó; Bognár, Péter; Pásztor, Szilárd; Barcza, Zoltán; Timár, Gábor; Lichtenberger, János; Ferencz, Csaba

    2015-04-01

    Monitoring the state and health of the vegetation is essential to understand causes and severity of environmental change and to prepare for the negative effects of climate change on plant growth and productivity. Satellite remote sensing is the fundamental tool to monitor and study the changes of vegetation activity in general and to understand its relationship with the climate fluctuations. Vegetation indices and other vegetation related measures calculated from remotely sensed data are widely used to monitor and characterize the state of the terrestrial vegetation. Normalized Difference Vegetation Index (NDVI) and the Enhanced Vegetation Index (EVI) are among the most popular indices that can be calculated from measurements of the MODerate resolution Imaging Spectroradiometer (MODIS) sensor onboard the NASA EOS-AM1/Terra and EOS-PM1/Aqua satellites (since 1999 and 2002 respectively). Based on the available, 15 years long MODIS data (2000-2014) the vegetation characteristics of Hungary was investigated in our research, primarily using vegetation indices. The MODIS NDVI and EVI (both part of the so-called MOD13 product of NASA) are freely available with a finest spatial resolution of 250 meters and a temporal resolution of 16 days since 2000/2002 (for Terra and Aqua respectively). The accuracy, the spatial resolution and temporal continuity of the MODIS products makes these datasets highly valuable despite of its relatively short temporal coverage. NDVI is also calculated routinely from the raw MODIS data collected by the receiving station of Eötvös Loránd University. In order to characterize vegetation activity and its variability within the Carpathian Basin the area-averaged annual cycles and their interannual variability were determined. The main aim was to find those years that can be considered as extreme according to specific indices. Using archive meteorological data the effects of extreme weather on vegetation activity and growth were investigated with emphasis on drought and heat waves. Te relationship between anomalies of vegetation characteristics and crop yield decrease in agricultural regions were characterised as well. The mean NDVI values of Hungary during the 15 years reveal the behaviour of the vegetation in the country, where the main land cover types (forest, agriculture and grassland) were distinguished as well. NDVI anomalies are analyzed separately for the main land cover types. Deviations from the potential maximum vegetation greenness are also calculated for the entire time period.

  1. Implications of Satellite Swath Width on Global Aerosol Optical Thickness Statistics

    NASA Technical Reports Server (NTRS)

    Colarco, Peter; Kahn, Ralph; Remer, Lorraine; Levy, Robert; Welton, Ellsworth

    2012-01-01

    We assess the impact of swath width on the statistics of aerosol optical thickness (AOT) retrieved by satellite as inferred from observations made by the Moderate Resolution Imaging Spectroradiometer (MODIS). We sub-sample the year 2009 MODIS data from both the Terra and Aqua spacecraft along several candidate swaths of various widths. We find that due to spatial sampling there is an uncertainty of approximately 0.01 in the global, annual mean AOT. The sub-sampled monthly mean gridded AOT are within +/- 0.01 of the full swath AOT about 20% of the time for the narrow swath sub-samples, about 30% of the time for the moderate width sub-samples, and about 45% of the time for the widest swath considered. These results suggest that future aerosol satellite missions with only a narrow swath view may not sample the true AOT distribution sufficiently to reduce significantly the uncertainty in aerosol direct forcing of climate.

  2. Identifying Hail Signatures in Satellite Imagery from the 9-10 August 2011 Severe Weather Event

    NASA Technical Reports Server (NTRS)

    Dryden, Rachel L.; Molthan, Andrew L.; Cole, Tony A.; Bell, Jordan

    2014-01-01

    Severe thunderstorms can produce large hail that causes property damage, livestock fatalities, and crop failure. However, detailed storm surveys of hail damage conducted by the National Weather Service (NWS) are not required. Current gaps also exist between Storm Prediction Center (SPC) hail damage estimates and crop-insurance payouts. NASA's Moderate Resolution Imaging Spectroradiometer (MODIS) instrument aboard the Terra and Aqua satellites can be used to support NWS damage assessments, particularly to crops during the growing season. The two-day severe weather event across western Nebraska and central Kansas during 9-10 August 2011 offers a case study for investigating hail damage signatures by examining changes in Normalized Difference Vegetation Index (NDVI) derived from MODIS imagery. By analyzing hail damage swaths in satellite imagery, potential economic losses due to crop damage can be quantified and further improve the estimation of weather impacts on agriculture without significantly increasing manpower requirements.

  3. Towards Monitoring Satellite Land Surface Temperature Production

    NASA Astrophysics Data System (ADS)

    Yu, P.; Yu, Y.; Liu, Y.; Wang, Z.; Zhang, X.

    2014-12-01

    Land surface temperature (LST) is of fundamental importance to the net radiation budget at the Earth surface and to monitoring the state of crops and vegetation, as well as an important indicator of both the greenhouse effect and the energy flux between the atmosphere and the land. Since its launch on October 28, 2011, the Suomi National Polar-orbiting Partnership (S-NPP) satellite has been continuously providing data for LST production; intensive validation and calibration of the LST data have been conducted since then. To better monitor the performance of the S-NPP LST product and evaluate different retrieval algorithms for potential improvement, a near-real-time monitoring system has been developed and implemented. The system serves as a tool for both the routine monitoring and the deep-dive researches. It currently consists of two major components: the global cross-satellite LST comparisons between S-NPP/VIIRS and MODIS/AQUA, and the LST validation with respect to in-situ observations from SURFRAD network. Results about cross-satellite comparisons, satellite-in situ LST validation, and evaluation of different retrieval algorithms are routinely generated and published through an FTP server of the system ftp. The results indicate that LST from the S-NPP is comparable to that from MODIS. A few case studies using this tool will be analyzed and presented.

  4. Digital herbarium archives as a spatially extensive, taxonomically discriminate phenological record; a comparison to MODIS satellite imagery

    NASA Astrophysics Data System (ADS)

    Park, Isaac W.

    2012-11-01

    This study demonstrates that phenological information included in digital herbarium archives can produce annual phenological estimates correlated to satellite-derived green wave phenology at a regional scale (R = 0.183, P = 0.03). Thus, such records may be utilized in a fashion similar to other annual phenological records and, due to their longer duration and ability to discriminate among the various components of the plant community, hold significant potential for use in future research to supplement the deficiencies of other data sources as well as address a wide array of important issues in ecology and bioclimatology that cannot be addressed easily using more traditional methods.

  5. A new framework for the top-down estimate of aerosol emission: Integrated analysis with satellite (MODIS) reflectance and the adjoint of a chemistry transport model (GEOS-chem) (Invited)

    NASA Astrophysics Data System (ADS)

    Wang, J.; Xu, X.; Henze, D. K.

    2010-12-01

    Passive remote sensing of aerosols in the visible spectrum is most sensitive to the change of aerosol optical thickness, an indicator of columnar aerosol mass in the first order, and is virtually not sensitive to the change of aerosol vertical profile. This is a unique advantage of using satellite measurements (other than surface observation) as a constraint in the top-down estimate of aerosol emission. In this presentation, we will demonstrate, for the first time, the use of satellite (MODIS) reflectance and the adjoint of a chemistry transport model (GEOS-chem) to constrain the aerosol emission. We will discuss the reasons for using reflectance other than operational satellite product as emission constraints, elaborate the challenges in defining the priori errors of aerosol emissions for the optimization, and provide an outlook of using satellite data from multi-sensors to tackle these challenges.

  6. NCEP GFS-GOCART DUST AOD Evaluation with MODIS Observation

    NASA Astrophysics Data System (ADS)

    Kim, D.; Huang, H.; Tang, Y.; Lu, S.; Lee, P.; Tsidulko, M.; McQueen, J.; Chin, M.; Diehl, T.; Stockwell, W. R.

    2008-12-01

    Mineral dust aerosol is the predominant natural atmospheric aerosol. Estimated dust emissions of about 3000 Mt/year with an approximate lifetime of a week, account for about 0.4 W/m2 of the global direct radiative effect at the top of the atmosphere. Depending on the conditions, mineral dust may be a major source of fine mode particulate matter (PM2.5). Recently a number of models have been developed to provide regional dust aerosol forecasts. However, there are substantial differences between the models' forecasts due to differences in meteorology, emission flux, and loss processes. Reducing differences between model and observation is a challenging task for all these models. This issue becomes even more significant as the spatial coverage of these models becomes global. The MODIS deployed in the Aqua and Terra satellites provides a reliable AOD measurement. These data have been widely used for model evaluation due to large spatial coverage and high observation frequency. Recently, the dust module from the NASA GOCART model has been incorporated with the NOAA/NCEP Global Forecasting Model System (GFS-GOCART) and the model is now producing preliminary forecasts. The model has about 1 degree (T126) resolution and predicts dust AOD at 550 nm every hour. In this study the AOD from MODIS (Level 2) has been used to evaluate air quality forecasts for episodes of a few days. The GFS-GOCART well captures Saharan dust events and gives reasonable agreement with MODIS observations, even though there are some discrepancies in source regions and remote areas.

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

    NASA Technical Reports Server (NTRS)

    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 their implications for biomass burning emissions assessment.

  8. Developing and Evaluating RGB Composite MODIS Imagery for Applications in National Weather Service Forecast Offices

    NASA Technical Reports Server (NTRS)

    Oswald, Hayden; Molthan, Andrew L.

    2011-01-01

    Satellite remote sensing has gained widespread use in the field of operational meteorology. Although raw satellite imagery is useful, several techniques exist which can convey multiple types of data in a more efficient way. One of these techniques is multispectral compositing. The NASA Short-term Prediction Research and Transition (SPoRT) Center has developed two multispectral satellite imagery products which utilize data from the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard NASA's Terra and Aqua satellites, based upon products currently generated and used by the European Organization for the Exploitation of Meteorological Satellites (EUMETSAT). The nighttime microphysics product allows users to identify clouds occurring at different altitudes, but emphasizes fog and low cloud detection. This product improves upon current spectral difference and single channel infrared techniques. Each of the current products has its own set of advantages for nocturnal fog detection, but each also has limiting drawbacks which can hamper the analysis process. The multispectral product combines each current product with a third channel difference. Since the final image is enhanced with color, it simplifies the fog identification process. Analysis has shown that the nighttime microphysics imagery product represents a substantial improvement to conventional fog detection techniques, as well as provides a preview of future satellite capabilities to forecasters.

  9. Global Characterization of Tropospheric Noise for InSAR Analysis Using MODIS Data

    NASA Astrophysics Data System (ADS)

    Yun, S.; Hensley, S.; Chaubell, M.; Fielding, E. J.; Pan, L.; Rosen, P. A.

    2013-12-01

    Radio wave's differential phase delay variation through the troposphere is one of the largest error sources in Interferometric Synthetic Aperture Radar (InSAR) measurements, and water vapor variability in the troposphere is known to be the dominant factor. We use the precipitable water vapor products from NASA's Moderate Resolution Imaging Spectroradiometer (MODIS) sensors mounted on Terra and Aqua satellites to produce tropospheric noise maps of InSAR. Then we extract a small set of characteristic parameters of its power spectral density curve and 1-D covariance function, and calculate the structure function to estimate the expected tropospheric noise level as a function of distance. The results serve two purposes: 1) to provide guidance on the expected covariance matrix for geophysical modeling, 2) to provide quantitative basis of the measurement requirements for the planned US L-band SAR mission. We build over a decade span (2000-2013) of a lookup table of the parameters derived from 2-by-2 degree tiles at 1-by-1 degree posting of global coverage, representing 10 days of each season in each year. The MODIS data were retrieved from OSCAR (Online Services for Correcting Atmosphere in Radar) server. MODIS images with 5 percent or more cloud cover were discarded. Cloud mask and sensor scanning artifacts were removed with interpolation and spectral filtering, respectively. We also mitigate topography dependent stratified tropospheric delay variation using the European Centre for Medium-Range Weather Forecasts (ECMWF) and Shuttle Radar Topography Mission Digital Elevation Models (SRTM DEMs).

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

    NASA Technical Reports Server (NTRS)

    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.

  11. Crop Surveillance Demonstration Using a Near-Daily MODIS Derived Vegetation Index Time Series

    NASA Technical Reports Server (NTRS)

    McKellip, Rodney; Ryan, Robert E.; Blonski, Slawomir; Prados, Don

    2005-01-01

    Effective response to crop disease outbreaks requires rapid identification and diagnosis of an event. A near-daily vegetation index product, such as a Normalized Difference Vegetation Index (NDVI), at moderate spatial resolution may serve as a good method for monitoring quick-acting diseases. NASA s Moderate Resolution Imaging Spectroradiometer (MODIS) instrument flown on the Terra and Aqua satellites has the temporal, spatial, and spectral properties to make it an excellent coarse-resolution data source for rapid, comprehensive surveillance of agricultural areas. A proof-of-concept wide area crop surveillance system using daily MODIS imagery was developed and tested on a set of San Joaquin cotton fields over a growing season. This area was chosen in part because excellent ground truth data were readily available. Preliminary results indicate that, at least in the southwestern part of the United States, near-daily NDVI products can be generated that show the natural variations in the crops as well as specific crop practices. Various filtering methods were evaluated and compared with standard MOD13 NDVI MODIS products. We observed that specific chemical applications that produce defoliation, which would have been missed using the standard 16-day product, were easily detectable with the filtered daily NDVI products.

  12. Integrated Cloud-Aerosol-Radiation Product using CERES, MODIS, CALIPSO and CloudSat Data

    NASA Technical Reports Server (NTRS)

    Sun-Mack, Sunny; Minnis, Patrick; Chen, Yan; Gibson, Sharon; Yi, Yuhong; Trepte, Qing; Wielicki, Bruce; Kato, Seiji; Winker, Dave

    2007-01-01

    This paper documents the development of the first integrated data set of global vertical profiles of clouds, aerosols, and radiation using the combined NASA A-Train data from the Aqua Clouds and Earth's Radiant Energy System (CERES) and Moderate Resolution Imaging Spectroradiometer (MODIS), Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO), and CloudSat. As part of this effort, cloud data from the CALIPSO lidar and the CloudSat radar are merged with the integrated column cloud properties from the CERES-MODIS analyses. The active and passive datasets are compared to determine commonalities and differences in order to facilitate the development of a 3- dimensional cloud and aerosol dataset that will then be integrated into the CERES broadband radiance footprint. Preliminary results from the comparisons for April 2007 reveal that the CERES-MODIS global cloud amounts are, on average, 0.14 less and 0.15 greater than those from CALIPSO and CloudSat, respectively. These new data will provide unprecedented ability to test and improve global cloud and aerosol models, to investigate aerosol direct and indirect radiative forcing, and to validate the accuracy of global aerosol, cloud, and radiation data sets especially in polar regions and for multi-layered cloud conditions.

  13. Cloud and Aerosol Properties, Precipitable Water, and Profiles of Temperature and Water Vapor from MODIS

    NASA Technical Reports Server (NTRS)

    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.

  14. Development of estimation method for crop yield using MODIS satellite imagery data and process-based model for corn and soybean in US Corn-Belt region

    NASA Astrophysics Data System (ADS)

    Lee, J.; Kang, S.; Jang, K.; Ko, J.; Hong, S.

    2012-12-01

    Crop productivity is associated with the food security and hence, several models have been developed to estimate crop yield by combining remote sensing data with carbon cycle processes. In present study, we attempted to estimate crop GPP and NPP using algorithm based on the LUE model and a simplified respiration model. The state of Iowa and Illinois was chosen as the study site for estimating the crop yield for a period covering the 5 years (2006-2010), as it is the main Corn-Belt area in US. Present study focuses on developing crop-specific parameters for corn and soybean to estimate crop productivity and yield mapping using satellite remote sensing data. We utilized a 10 km spatial resolution daily meteorological data from WRF to provide cloudy-day meteorological variables but in clear-say days, MODIS-based meteorological data were utilized to estimate daily GPP, NPP, and biomass. County-level statistics on yield, area harvested, and productions were used to test model predicted crop yield. The estimated input meteorological variables from MODIS and WRF showed with good agreements with the ground observations from 6 Ameriflux tower sites in 2006. For examples, correlation coefficients ranged from 0.93 to 0.98 for Tmin and Tavg ; from 0.68 to 0.85 for daytime mean VPD; from 0.85 to 0.96 for daily shortwave radiation, respectively. We developed county-specific crop conversion coefficient, i.e. ratio of yield to biomass on 260 DOY and then, validated the estimated county-level crop yield with the statistical yield data. The estimated corn and soybean yields at the county level ranged from 671 gm-2 y-1 to 1393 gm-2 y-1 and from 213 gm-2 y-1 to 421 gm-2 y-1, respectively. The county-specific yield estimation mostly showed errors less than 10%. Furthermore, we estimated crop yields at the state level which were validated against the statistics data and showed errors less than 1%. Further analysis for crop conversion coefficient was conducted for 200 DOY and 280 DOY. For the case of 280 DOY, Crop yield estimation showed better accuracy for soybean at county level. Though the case of 200 DOY resulted in less accuracy (i.e. 20% mean bias), it provides a useful tool for early forecasting of crop yield. We improved the spatial accuracy of estimated crop yield at county level by developing county-specific crop conversion coefficient. Our results indicate that the aboveground crop biomass can be estimated successfully with the simple LUE and respiration models combined with MODIS data and then, county-specific conversion coefficient can be different with each other across different counties. Hence, applying region-specific conversion coefficient is necessary to estimate crop yield with better accuracy.

  15. Coherent Evaluation of Aerosol Data Products from Multiple Satellite Sensors

    NASA Technical Reports Server (NTRS)

    Ichoku, Charles

    2011-01-01

    Aerosol retrieval from satellite has practically become routine, especially during the last decade. However, there is often disagreement between similar aerosol parameters retrieved from different sensors, thereby leaving users confused as to which sensors to trust for answering important science questions about the distribution, properties, and impacts of aerosols. As long as there is no consensus, and the inconsistencies are not well characterized and understood, there will be no way of developing reliable model inputs and climate data records from satellite aerosol measurements. Fortunately, the Aerosol Robotic Network (AERONET) is providing well-calibrated globally representative ground-based aerosol measurements corresponding to the satellite-retrieved products. Through a recently developed web-based Multi-sensor Aerosol Products Sampling System (MAPSS), we are utilizing the advantages offered by collocated AERONET and satellite products to characterize and evaluate aerosol retrieval from multiple sensors. Indeed, MAPSS and its companion statistical tool AeroStat are facilitating detailed comparative uncertainty analysis of satellite aerosol measurements from Terra-MODIS, Aqua-MODIS, Terra-MISR, Aura-OMI, Parasol-POLDER, and Calipso-CALIOP. In this presentation, we will describe the strategy of the MAPSS system, its potential advantages for the aerosol community, and the preliminary results of an integrated comparative uncertainly analysis of aerosol products from multiple satellite sensors.

  16. Growing up MODIS: Towards a mature aerosol climate data record

    NASA Astrophysics Data System (ADS)

    Levy, Robert C.

    2013-05-01

    Aerosols are major players within the Earth's climate system, affecting the radiation budget, clouds and the hydrological cycle. In high concentrations near the surface, aerosols (or particulate matter, PM) affect visibility, impact air quality, and can contribute to poor health. Among others, Yoram Kaufman recognized the importance of aerosols to climate, and helped to design new instrumentation and algorithms to retrieve and quantify global aerosol properties. One instrument, known as the Moderate Imaging Resolution Spectro-radiometer (MODIS), was deployed on the AM-1 satellite (later known as Terra), part of NASA's Earth Observing System (EOS). In 1998, armed with an M.S. and job experience in neither aerosols nor satellites, I was looking for a new job. I somehow found my way to the MODIS Aerosol team. It was only a year before Terra launch, and most major decisions about the MODIS aerosol retrieval algorithms had been finalized. Since then, we worked through launch, initial evaluation of the product with AERONET and field deployments, and continued efforts to understand the product and refine retrieval algorithms. I have had opportunities to participate in field experiments, write papers, and earn my PhD. The "second generation" algorithm for aerosol retrieval over land has been hugely successful. We have collected nearly a half-million collocations with AERONET and other dataseis, made new discoveries, and have contributed to research and operational projects globally. Due to the dedication of the entire team, the MODIS aerosol product now is one of the highlights of NASA's EOS program. It is used for climate research and air quality forecasting, as well for applications not even considered before the MODIS era. More recently, a focus is on stitching the MODIS aerosol product into the "climate data record" (CDR) for global aerosol, determining whether the product has sufficient length, consistency and continuity to determine climate variability and change. 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.

  17. Spatially Complete Surface Albedo Data Sets: Value-Added Products Derived from Terra MODIS Land Products

    NASA Technical Reports Server (NTRS)

    Moody, Eric G.; King, Michael D.; Platnick, Steven; Schaaf, Crystal B.; Gao, Feng

    2004-01-01

    Spectral land surface albedo is an important parameter for describing the radiative properties of the Earth. Accordingly it reflects the consequences of natural and human interactions, such as anthropogenic, meteorological, and phenological effects, on global and local climatological trends. Consequently, albedos are integral parts in a variety of research areas, such as general circulation models (GCMs), energy balance studies, modeling of land use and land use change, and biophysical, oceanographic, and meteorological studies. Recent observations of diffuse bihemispherical (white-sky) and direct beam directional hemispherical (black-sky ) land surface albedo included in the MOD43B3 product from MODIS instruments aboard NASA's Terra and Aqua satellite platforms have provided researchers with unprecedented spatial, spectral, and temporal characteristics. Cloud and seasonal snow cover, however, curtail retrievals to approximately half the global land surfaces on an annual equal-angle basis, precluding MOD43B3 albedo products from direct inclusion in some research projects and production environments.

  18. Beyond MODIS: Developing an aerosol climate data record

    NASA Astrophysics Data System (ADS)

    Levy, R. C.; Mattoo, S.; Munchak, L. A.; Patadia, F.; Laszlo, I.; Holz, R.

    2013-12-01

    As defined by the National Research Council, a climate data record (CDR) is a time series of measurements of sufficient length, consistency, and continuity to determine climate variability and change. As one of our most pressing research questions concerns changes in global direct aerosol radiative forcing (DARF), creating an aerosol CDR is of high importance. To reduce our uncertainties in DARF, we need uncertainty in global aerosol optical depth (AOD) reduced to ×0.02 or better, or about 10% of global mean AOD (~0.15-0.20). To quantify aerosol trends with significance, we also need a stable time series at least 20-30 years. By this Fall-2013 AGU meeting, the Moderate Resolution Imaging Spectrometer (MODIS) has been flying on NASA's Terra and Aqua satellites for 14 years and 11.5 years, respectively. During this time, we have fine-tuned the aerosol retrieval algorithms and data processing protocols, resulting in a well characterized product of aerosol optical depth (AOD). MODIS AOD has been extensively compared to ground-based sunphotometer data, showing per-retrieval expected error (EE) of ×(0.03 + 5%) over ocean, and has been generally adopted as a robust and stable environmental data record (EDR). With the 2011 launch of the Visible and Infrared Imaging Radiometer Suite (VIIRS) aboard Suomi-NPP, we have begun a new aerosol time series. The VIIRS AOD product has stabilized to the point where, compared to ground-based AERONET sunphotometer, the VIIRS AOD is within similar EE envelope as MODIS. Thus, if VIIRS continues to perform as expected, it too can provide a robust and stable aerosol EDR. What will it take to stitch MODIS and VIIRS into a robust aerosol CDR? Based on the recent experience of MODIS 'Collection 6' development, there are many details of aerosol retrieval that each lead to ×0.01 uncertainties in global AOD. These include 'radiative transfer' assumptions such as calculations for gas absorption and sea-level Rayleigh optical depth, 'decision making' assumptions such as cloud masking and pixel selection, as well as 'retrieval' assumptions such as aerosol type, and surface reflectance model. Also there are instrument issues such as calibration and geo-location, which even on the level of 1-2%, will lead to 10% error in retrieved AOD. At this point, however, many of these issues have been solved, or are being quantified for MODIS and VIIRS. In the past year, we created a generic dark-target aerosol retrieval algorithm, which can be applied to MODIS, VIIRS, or any other sensor with a similar set of wavelength bands. We applied the same radiative transfer codes for creating lookup tables, the same protocols for deriving non-aerosol assumptions, and the same criteria for cloud masking. Although there are still inconsistencies to work out, this generic algorithm is being applied to selected months having VIIRS/MODIS overlap. Comparing to AERONET, and with each other, we quantify the statistical agreement between MODIS and VIIRS, both for the official algorithms run on each sensor, as well as for our generic algorithm run on both.

  19. Intercomparison between satellite-derived aerosol optical thickness and PM2.5 mass: Implications for air quality studies

    NASA Astrophysics Data System (ADS)

    Wang, Jun; Christopher, Sundar A.

    2003-11-01

    We explore the relationship between column aerosol optical thickness (AOT) derived from the Moderate Resolution Imaging SpectroRadiometer (MODIS) on the Terra/Aqua satellites and hourly fine particulate mass (PM2.5) measured at the surface at seven locations in Jefferson county, Alabama for 2002. Results indicate that there is a good correlation between the satellite-derived AOT and PM2.5 (linear correlation coefficient, R = 0.7) indicating that most of the aerosols are in the well-mixed lower boundary layer during the satellite overpass times. There is excellent agreement between the monthly mean PM2.5 and MODIS AOT (R > 0.9), with maximum values during the summer months due to enhanced photolysis. The PM2.5 has a distinct diurnal signature with maxima in the early morning (6:00 ~ 8:00AM) due to increased traffic flow and restricted mixing depths during these hours. Using simple empirical linear relationships derived between the MODIS AOT and 24hr mean PM2.5 we show that the MODIS AOT can be used quantitatively to estimate air quality categories as defined by the U.S. Environmental Protection Agency (EPA) with an accuracy of more than 90% in cloud-free conditions. We discuss the factors that affect the correlation between satellite-derived AOT and PM2.5 mass, and emphasize that more research is needed before applying these methods and results over other areas.

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

    NASA Technical Reports Server (NTRS)

    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.

  1. SatCam: A mobile application for coordinated ground/satellite observation of clouds and validation of satellite-derived cloud mask products.

    NASA Astrophysics Data System (ADS)

    Gumley, L.; Parker, D.; Flynn, B.; Holz, R.; Marais, W.

    2011-12-01

    SatCam is an application for iOS devices that allows users to collect observations of local cloud and surface conditions in coordination with an overpass of the Terra, Aqua, or NPP satellites. SatCam allows users to acquire images of sky conditions and ground conditions at their location anywhere in the world using the built-in iPhone or iPod Touch camera at the same time that the satellite is passing overhead and viewing their location. Immediately after the sky and ground observations are acquired, the application asks the user to rate the level of cloudiness in the sky (Completely Clear, Mostly Clear, Partly Cloudy, Overcast). For the ground observation, the user selects their assessment of the surface conditions (Urban, Green Vegetation, Brown Vegetation, Desert, Snow, Water). The sky condition and surface condition selections are stored along with the date, time, and geographic location for the images, and the images are uploaded to a central server. When the MODIS (Terra and Aqua) or VIIRS (NPP) imagery acquired over the user location becomes available, a MODIS or VIIRS true color image centered at the user's location is delivered back to the SatCam application on the user's iOS device. SSEC also proposes to develop a community driven SatCam website where users can share their observations and assessments of satellite cloud products in a collaborative environment. SSEC is developing a server side data analysis system to ingest the SatCam user observations, apply quality control, analyze the sky images for cloud cover, and collocate the observations with MODIS and VIIRS satellite products (e.g., cloud mask). For each observation that is collocated with a satellite observation, the server will determine whether the user scored a "hit", meaning their sky observation and sky assessment matched the automated cloud mask obtained from the satellite observation. The hit rate will be an objective assessment of the accuracy of the user's sky observations. Users with high hit rates will be identified automatically and their observations will be used globally to evaluate the performance of the MODIS cloud mask algorithm for Terra and Aqua and the VIIRS cloud mask algorithm for NPP. The user's assessment of the ground conditions will also be used to evaluate the cloud mask accuracy in selecting the correct surface type at the user's location, which is an important element in the decision path used internally by the cloud mask algorithm. This presentation will describe the SatCam application, how it is used, and show examples of SatCam observations.

  2. MODIS TEB calibration approach in collection 6

    NASA Astrophysics Data System (ADS)

    Wenny, Brian N.; Wu, Aisheng; Madhavan, Sriharsha; Wang, Zhipeng; Li, Yonghong; Chen, Na; Chiang, Kwo-Fu; Xiong, Xiaoxiong

    2012-09-01

    The MODerate Resolution Imaging Spectroradiometer (MODIS) is a heritage sensor operating on both the Terra and Aqua platforms, and has collected remotely sensed data for a combined mission time of twenty plus years. The instrument robustness and performance over their lifetimes has been very satisfactory and is well calibrated using the onboard calibrators (OBC). The radiometric fidelity of the MODIS instruments has ensured the high quality of science products derived from the Level 1B (L1B) imagery. MODIS Thermal Emissive Bands (TEB) are calibrated on-orbit using an on-board blackbody (BB) and through the space-view (SV) port. The MODIS BB is nominally controlled at 290K for Terra and at 285K for Aqua. Periodically, a BB warm-up and cool-down (WUCD) process is implemented, during which the BB temperatures vary from instrument ambient (approximately 272K) to 315K. The calibration coefficients for the 16 TEB bands are characterized using the above mentioned on-board BB operations (i.e. using nominal and WUCD operations). This paper will focus on the calibration algorithms of the TEB developed for collection 6 (C6) processing, its impact on the Level 1B (L1B) product in comparison to collection 5 (C5), and the methodology for issuing a Look Up Table (LUT) update for L1B processing.

  3. Potentials and limitations for scaling plant photosynthesis across northern latitudes using MODIS (Invited)

    NASA Astrophysics Data System (ADS)

    Hilker, T.; Hall, F.; Coops, N.; Lyapustin, A.; Tucker, C. J.

    2013-12-01

    Our ability to quantify terrestrial climate feedbacks will depend on a comprehensive understanding of the carbon, water and energy balance over land. Models of photosynthesis have long been challenged by the complexity of the biophysical mechanisms driving gross primary productivity (GPP) and the large number of factors contributing to or limiting photosynthesis at a given time. Currently, neither enzyme kinetics, nor radiation limited models allow sufficiently accurate estimates of GPP and as a result, large uncertainties remain with respect to future carbon uptake and climate scenarios. One possible way to address these issues is to combine photosynthesis models with satellite observations to obtain spatially explicit and temporally continuous estimates of photosynthesis by means of data assimilation. Remote sensing observations can be used to infer GPP as the product of photosynthetically active radiation (PAR) [Wm-2], the fraction of it being absorbed by the green vegetation elements (fPAR) and the efficiency ɛ (g CMJ-1) with which plants can use this absorbed radiation energy to produce biomass. In previous work, we have developed a physically-based approach to use multi-angle observations of the photochemical reflectance index, a narrow band index linked to the xanthophyll cycle of vegetation to robustly infer GPP across vegetation types. The technique eliminates extraneous effects of PRI by comparing reflectance of the identical canopy from different view angles and estimating differences in photosynthetic down-regulation as a function of canopy shading. Broader application has so far been limited by the availability of multi-angle satellite data. MODIS observations are acquired at different angles but these acquisitions are obtained across track. In high northern latitudes, there is a high frequency of satellite passes due to the near polar orbits of the Terra and Aqua spacecrafts. This will allow us to combine MODIS observation from both platforms from at least two different view angles within a short elapsed time (Δt) during which GPP can be considered constant. High northern latitudes therefore provide unique opportunities for scaling tower level estimates of PRI to the landscape, thereby potentially allowing data assimilation of GPP from direct satellite based estimates. Here, we investigate the potential and limitations of combining MODIS observations from the Terra and Aqua platforms with modeling techniques to obtain spatially and temporally continuous estimates of GPP and show new opportunities for modeling the carbon and energy balance.

  4. Examining the quality of MODIS reflectance products using a four-band spectroradiometer

    NASA Astrophysics Data System (ADS)

    Nguy-Robertson, A. L.; Sakamoto, T.; Arkebauer, T.; Suyker, A. E.; Peng, Y.; Gitelson, A. A.

    2012-12-01

    There is a need to validate satellite products across a wide range of land cover types. This study examines the quality of MODIS reflectance products over a two year period (2010-2011) in three agricultural fields near Mead, Nebraska, USA using 4-band spectroradiometers. Two of the three sites are under irrigated continuous maize. The third site is a rainfed maize/soybean rotation. A pair of four-band spectroradiometers (SKYE instruments) at each site collect downwelling irradiance and upwelling radiance in four spectral regions (green - 536.5-561.5 nm, red - 664.5-675.5 nm, red edge - 704.5-715.5 nm, and near infrared - 862-874 nm). The ratio of these instruments signals was used to determine reflectance at half hour intervals. The median of these reflectances collected two hours before and after solar noon were used to characterize the daily reflectance values for each site. The MODIS 8-day composite data for both Terra and Aqua sensors were compared to their respective SKYE reflectance and vegetation indices (VIs; e.g. NDVI, EVI, WDRVI) on the date of data acquisition. These relationships were quite strong, suggesting that the atmospheric correction and pixel selection criteria for the 8-day composites of reflectance and VI products are accurate. This methodology for examining satellite products can also be used for other satellite sensors, such as those containing a red edge band (e.g. MERIS, Sentinel-2, OLCI, etc.). Using ground measured LAI measurements and GPP measured by eddy-covariance flux towers, we found that both the SKYE and MODIS spectroradiometers are able to provide accurate estimation of crop biophysical characteristics such as LAI, biomass, and GPP.

  5. Comparasion of Cloud Cover restituted by POLDER and MODIS

    NASA Astrophysics Data System (ADS)

    Zeng, S.; Parol, F.; Riedi, J.; Cornet, C.; Thieuxleux, F.

    2009-04-01

    PARASOL and AQUA are two sun-synchronous orbit satellites in the queue of A-Train satellites that observe our earth within a few minutes apart from each other. Aboard these two platforms, POLDER and MODIS provide coincident observations of the cloud cover with very different characteristics. These give us a good opportunity to study the clouds system and evaluate strengths and weaknesses of each dataset in order to provide an accurate representation of global cloud cover properties. This description is indeed of outermost importance to quantify and understand the effect of clouds on global radiation budget of the earth-atmosphere system and their influence on the climate changes. We have developed a joint dataset containing both POLDER and MODIS level 2 cloud products collocated and reprojected on a common sinusoidal grid in order to make the data comparison feasible and veracious. Our foremost work focuses on the comparison of both spatial distribution and temporal variation of the global cloud cover. This simple yet critical cloud parameter need to be clearly understood to allow further comparison of the other cloud parameters. From our study, we demonstrate that on average these two sensors both detect the clouds fairly well. They provide similar spatial distributions and temporal variations:both sensors see high values of cloud amount associated with deep convection in ITCZ, over Indonesia, and in west-central Pacific Ocean warm pool region; they also provide similar high cloud cover associated to mid-latitude storm tracks, to Indian monsoon or to the stratocumulus along the west coast of continents; on the other hand small cloud amounts that typically present over subtropical oceans and deserts in subsidence aeras are well identified by both POLDER and MODIS. Each sensor has its advantages and inconveniences for the detection of a particular cloud types. With higher spatial resolution, MODIS can better detect the fractional clouds thus explaining as one part of a positive bias in any latitude and in any viewing angle with an order of 10% between the POLDER cloud amount and the so-called MODIS "combined" cloud amount. Nevertheless it is worthy to note that a negative bias of about 10% is obtained between the POLDER cloud amount and the MODIS "day-mean" cloud amount. Main differences between the two MODIS cloud amount values are known to be due to the filtering of remaining aerosols or cloud edges. due to both this high spatial resolution of MODIS and the fact that "combined" cloud amount filters cloud edges, we can also explain why appear the high positive bias regions over subtropical ocean in south hemisphere and over east Africa in summer. Thanks to several channels in the thermal infrared spectral domain, MODIS detects probably much better the thin cirrus especially over land, thus causing a general negative bias for ice clouds. The multi-spectral capability of MODIS also allows for a better detection of low clouds over snow or ice, Hence the (POLDER-MODIS) cloud amount difference is often negative over Greenland, Antarctica, and over the continents at middle-high latitudes in spring and autumn associated to the snow coverage. The multi-spectral capability of MODIS also makes the discrimination possible between the biomass burning aerosols and the fractional clouds over the continents. Thus a positive bias appears in central Africa in summer and autumn associated to important biomass burning events. Over transition region between desert and non-desert, the presence of large negative bias (POLDER-MODIS) of cloud amount maybe partly due to MODIS pixel falsely labeled the desert as cloudy, where MODIS algorithm uses static desert mask. This is clearly highlighted in south of Sahara in spring and summer where we find a bias negative with an order of -0.1. What is more, thanks to its multi-angular capability, POLDER can discriminate the sun-glint region thus minimizing the dependence of cloud amount on view angle. It makes the detection of high clouds easier over a black surface thanks to its polarization character.

  6. Evaluation of MODIS and VIIRS Albedo Products Using Ground and Airborne Measurements and Development of Ceos/Wgcv/Lpv Albedo Ecv Protocols

    NASA Astrophysics Data System (ADS)

    Wang, Z.; Roman, M. O.; Schaaf, C.; Sun, Q.; Liu, Y.; Saenz, E. J.; Gatebe, C. K.

    2014-12-01

    Surface albedo, defined as the ratio of the hemispheric reflected solar radiation flux to the incident flux upon the surface, is one of the essential climate variables and quantifies the radiation interaction between the atmosphere and the land surface. An absolute accuracy of 0.02-0.05 for global surface albedo is required by climate models. The MODerate resolution Imaging Spectroradiometer (MODIS) standard BRDF/albedo product makes use of a linear "kernel-driven" RossThick-LiSparse Reciprocal (RTLSR) BRDF model to describe the reflectance anisotropy. The surface albedo is calculated by integrating the BRDF over the above ground hemisphere. While MODIS Terra was launched in Dec 1999 and MODIS Aqua in 2002, the Visible Infrared Imaging Radiometer Suite (VIIRS) on the Suomi-NPP satellite was launched more recently on October 28, 2011. Thus a long term record of BRDF, albedo and Nadir BRDF-Adjusted Reflectance (NBAR) products from VIIRS can be generated through MODIS heritage algorithms. Several investigations have evaluated the MODIS albedo products during the growing season, as well as during dormant and snow covered periods. The Land Product Validation (LPV) sub-group of the Committee on Earth Observation Satellites (CEOS) Working Group on Calibration and Validation (WGCV) aims to address the challenges associated with the validation of global land products. The validation of global surface radiation/albedo products is one of the LPV subgroup activities. In this research, a reference dataset covering various land surface types and vegetation structure is assembled to assess the accuracy of satellite albedo products. This dataset includes in situ data (Baseline Surface Radiation Network (BSRN), FLUXNET and Long Term Ecological Research network (LTER) etc.) and airborne measurements (e.g. Cloud Absorption Radiometer (CAR)). Spatially representative analysis is applied to each site to establish whether the ground measurements can adequately represent moderate spatial resolution remotely sensed albedo products.

  7. Satellites

    SciTech Connect

    Burns, J.A.; Matthews, M.S.

    1986-01-01

    The present work is based on a conference: Natural Satellites, Colloquium 77 of the IAU, held at Cornell University from July 5 to 9, 1983. Attention is given to the background and origins of satellites, protosatellite swarms, the tectonics of icy satellites, the physical characteristics of satellite surfaces, and the interactions of planetary magnetospheres with icy satellite surfaces. Other topics include the surface composition of natural satellites, the cratering of planetary satellites, the moon, Io, and Europa. Consideration is also given to Ganymede and Callisto, the satellites of Saturn, small satellites, satellites of Uranus and Neptune, and the Pluto-Charon system.

  8. MODIS On-Orbit Calibration and Lessons Learned

    NASA Technical Reports Server (NTRS)

    Xiong, Jack

    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 extend and enhance their long-term data records. Its follow-on instrument, the Visible/Infrared Imager Radiometer Suite (VIIRS), was launched on-board the Suomi National Polar-orbiting Partnership (NPP) spacecraft October 28, 2011. MODIS collects data in 36 spectral bands, covering wavelengths from 0.41 to 14.S!Jlll, and at 250m, SOOm, and lkm spatial resolutions (nadir). MODIS on-orbit calibration is provided by a set of onboard calibrators (OBC), including a solar diffuser (SO), a solar diffuser stability monitor (SDSM), a blackbody (BB), and a spectroradiometric calibration assembly (SRCA). In addition to the onboard calibrators, regular lunar observations are made by both Terra and Aqua MODIS to track their calibration stability in the reflective solar region. This tutorial session provides an overview of MODIS on-orbit calibration and characterization methodologies. It discusses challenging issues and lessons learned from sensor design, operation, calibration, and inter-comparisons. Examples of instrument on-orbit performance are illustrated with a focus on the improvements made based on various lessons learned. It is expected that MODIS experience and lessons will continue to provide valuable information for future earth observing missions/sensors.

  9. MODIS Direct Broadcast and Remote Sensing Applications

    NASA Technical Reports Server (NTRS)

    Tsay, Si-Chee

    2004-01-01

    The Moderate Resolution Imaging Spectroradiometer (MODIS) was developed by NASA and launched onboard both Terra spacecraft on December 18, 1999 and Aqua spacecraft on May 4, 2002. MODIS scans 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, and provides images in 36 spectral bands between 0.415 and 14.235 microns with spatial resolutions of 250 m (2 bands), 500 m (5 bands) and 1000 m (29 bands). Equipped with direct broadcast capability, the MODIS measurements can be received worldwide real time. There are 82 ingest sites (over 900 users, listed on the Direct Readout Portal) around the world for Terra/Aqua-MODIS Direct Broadcast DB) downlink. This represents 27 (6 from EOS science team members) science research organizations for DB land, ocean and atmospheric processing, and 53 companies that base their application algorithms and value added products on DB data. In this paper we will describe the various methods being used for the remote sensing of cloud properties using MODIS data, focusing primarily on the MODIS cloud mask used to distinguish clouds, clear sky, heavy aerosol, and shadows on the ground, and on the remote sensing of aerosol/cloud optical properties, especially optical thickness and effective particle size. Additional properties of clouds derived from multispectral thermal infrared measurements, especially cloud top pressure and emissivity, will also be described. Preliminary results will be presented and discussed their implications in regional-to-global climatic effects.

  10. MODIS Solar Diffuser On-orbit Performance

    NASA Technical Reports Server (NTRS)

    Xiong, Xiaoxiong; Chen, H.; Choi, T.; Sun, J.; Angal, A.

    2008-01-01

    MODIS is a key instrument for the NASA Earth Observing System (EOS), currently operated on both the Terra and Aqua missions. Each MODIS instrument has 20 reflective solar bands (RSBs) and 16 thermal emissive bands (TEBs). MODIS RSB on-orbit calibration is reflectance based using an on-board solar diffuser (SD). The SD bi-directional reflectance factors (BRFs) were characterized pre-launch using reference diffuser samples, which are traceable to NIST reflectance standards. The SD BRF on-orbit degradation (or change) is tracked by another onboard device, called the solar diffuser stability monitor (SDSM). The SDSM is operated during each scheduled SD calibration event, making alternate observations of direct sunlight and the diffusely reflected sunlight from the SD. The time series of the ratios of SDSM's SD view to its Sun view provide SD degradation information. This paper presents and compares the Terra and Aqua MODIS SD on-orbit performance. Results show that the SD on-orbit degradation depends on the amount of solar exposure of the SD plate. In addition, it is strongly wavelengthdependent, with a larger degradation rate at shorter wavelengths. For Terra MODIS, an SD door anomaly occurred in May 2003 that led to a decision to fix the door permanently at an "open" position. Since then, the SD degradation rate has significantly increased due to more frequent solar exposure. As expected, the SD on-orbit performance directly impacts the RSB calibration performance. The lessons learned from MODIS on-orbit calibration will provide useful insights into the development and operation of future SD calibration systems.

  11. Mapping the Distribution of Cloud Forests Using MODIS Imagery

    NASA Astrophysics Data System (ADS)

    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 accuracy for its intended purposes. Even periods as short as one month are sufficient for depicting the location of most cloud forest environments. However, we are proceeding to distinguish different characteristics of cloud forests, depending on the overall frequency of cloudiness, the seasonality of cloudiness, and the interannual variability of cloudiness. These results should be useful to those seeking to describe relationships between the physical characteristics of the cloud forests and their biological environment.

  12. MODIS Global Sea Surface Temperature

    NASA Technical Reports Server (NTRS)

    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

  13. MODIS solar reflective calibration traceability

    NASA Astrophysics Data System (ADS)

    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.

  14. Evaluation of AIRS, MODIS, and HIRS 11 Micron Brightness Temperature Difference Changes from 2002 through 2006

    NASA Technical Reports Server (NTRS)

    Broberg, Steven E.; Aumann, Hartmut H.; Gregorich, David T.; Xiong, X.

    2006-01-01

    In an effort to validate the accuracy and stability of AIRS data at low scene temperatures (200-250 K range), we evaluated brightness temperatures at 11 microns with Aqua MODIS band 31 and HIRS/3 channel 8 for Antarctic granules between September 2002 and May 2006. We found excellent agreement with MODIS (at the 0.2 K level) over the full emperature range in data from early in the Aqua mission. However, in more recent data, starting in April 2005, we found a scene temperature dependence in MODIS-AIRS brightness temperature differences, with a discrepancy of 1- 1.5 K at 200 K. The comparison between AIRS and HIRS/3 (channel 8) on NOAA 16 for the same time period yields excellent agreement. The cause and time dependence of the disagreement with MODIS is under evaluation, but the change was coincident with a change in the MODIS production software from collection 4 to 5.

  15. Intercomparison between MODIS 3km aerosol optical depth product and ground PM10 measurements over Athens, Greece

    NASA Astrophysics Data System (ADS)

    Retalis, Adrianos; Paronis, Dimitris; Katsanos, Dimitris

    2015-10-01

    Satellite imagery has been considered as an add-on tool to air quality and pollution monitoring due to its extensive spatial and temporal coverage of the Earth's surface and atmosphere. The most widely used satellite parameter is the Aerosol Optical Depth (AOD). AOD has been extensively used to evaluate and enhance the satellite-based estimates of ground-level particulate matter (PM) as well as to reduce uncertainties in the studies of global health applications. This study attempts to identify correlations between AOD values retrieved from the new MODIS/Aqua high resolution 3km aerosol product and ground-based PM10 measurements obtained within the period 2002-2012 in the area of Athens, Greece. In parallel, it attempts to assess the applicability of the so called mixed effects models which take into account both the spatial and temporal variability of the underlying uncertainties in the estimation of PM10 levels from MODIS AOD measurements. The ground PM10 recordings were acquired from the archive of the in-situ operational air quality monitoring network of Athens. Results indicated that the new AOD product of 3km estimated better PM10 values against the AOD 10km product. Thus, the new 3km product may be better at characterizing aerosol distributions on local scale although bias was observed.

  16. A Real-Time MODIS Vegetation Composite for Land Surface Models and Short-Term Forecasting

    NASA Technical Reports Server (NTRS)

    Case, Jonathan L.; LaFontaine, Frank J.; Kumar, Sujay V.; Jedlovec, Gary J.

    2011-01-01

    The NASA Short-term Prediction Research and Transition (SPoRT) Center is producing real-time, 1- km resolution Normalized Difference Vegetation Index (NDVI) gridded composites over a Continental U.S. domain. These composites are updated daily based on swath data from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor aboard the polar orbiting NASA Aqua and Terra satellites, with a product time lag of about one day. A simple time-weighting algorithm is applied to the NDVI swath data that queries the previous 20 days of data to ensure a continuous grid of data populated at all pixels. The daily composites exhibited good continuity both spatially and temporally during June and July 2010. The composites also nicely depicted high greenness anomalies that resulted from significant rainfall over southwestern Texas, Mexico, and New Mexico during July due to early-season tropical cyclone activity. The SPoRT Center is in the process of computing greenness vegetation fraction (GVF) composites from the MODIS NDVI data at the same spatial and temporal resolution for use in the NASA Land Information System (LIS). The new daily GVF dataset would replace the monthly climatological GVF database (based on Advanced Very High Resolution Radiometer [AVHRR] observations from 1992-93) currently available to the Noah land surface model (LSM) in both LIS and the public version of the Weather Research and Forecasting (WRF) model. The much higher spatial resolution (1 km versus 0.15 degree) and daily updates based on real-time satellite observations have the capability to greatly improve the simulation of the surface energy budget in the Noah LSM within LIS and WRF. Once code is developed in LIS to incorporate the daily updated GVFs, the SPoRT Center will conduct simulation sensitivity experiments to quantify the impacts and improvements realized by the MODIS real-time GVF data. This presentation will describe the methodology used to develop the 1-km MODIS NDVI composites and show sample output from summer 2010, compare the MODIS GVF data to the AVHRR monthly climatology, and illustrate the sensitivity of the Noah LSM within LIS and/or the coupled LIS/WRF system to the new MODIS GVF dataset.

  17. Accessing Recent Trend of Land Surface Temperature from Satellite Observations

    NASA Astrophysics Data System (ADS)

    Shen, S.; Leptoukh, G. G.; Romanov, P.

    2011-12-01

    Land surface temperature (LST) is an important element to measure the state of the terrestrial ecosystems and to study the surface energy budgets. In support of the land cover/land use change related international program MAIRS (Monsoon Asia Integrated Regional Study), we have collected the global monthly LST measured by MODIS since the beginning of the missions. The MODIS LST time series have ~11 years of data from Terra since 2000 and ~9 years of data from Aqua since 2002, which makes possible to study the recent climate, such as trend and variability. In this study, monthly climatology from two satellite platforms are calculated and compared. The spatial patterns of LST trends are accessed, focusing on the Asian Monsoon region. Furthermore, the MODIS LST trends are compared with the skin temperature trend from the NASA's atmospheric assimilation model, MERRA (MODERN ERA RETROSPECTIVE-ANALYSIS FOR RESEARCH AND APPLICATIONS), which has longer data record since 1979. The calculated climatology and anomaly of MODIS LST will be integrated into the online visualization system, Giovanni, at NASA GES DISC for easy access and use by scientists and general public.

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

    NASA Technical Reports Server (NTRS)

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

    2007-01-01

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

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

    NASA Astrophysics Data System (ADS)

    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.

  20. An Intercomparison of AVHRR , MERIS, AATSR and MODIS radiances using a SNO approach

    NASA Astrophysics Data System (ADS)

    Johansson, E.; Karlsson, K.-G.

    2012-04-01

    To be able to create climate data sets containing data from several satellite instruments, the measurements from the different sensors have to be homogeneous. For measurements in the infrared part of the spectrum this is normally accomplished by using on-board reference targets (blackbodies). As a contrast, calibration techniques applied to visible channels have often been using reference measurements from the ground, a ground truth. This technique is often called Vicarious calibration since no on-board reference is available. It also means that potential calibration errors can only be adjusted in delayed mode after having collected enough reference data (often limited by availability of cloud-free reference surfaces). In this presentation the radiances of the common channels at 0.67, 0.87, 1.6, 3.7, 11 and 12 micron for the Advanced Very High Resolution Radiometer (AVHRR), the Advanced Along-Track Scanning Radiometer (AATSR) and the Medium-spectral Resolution, Imaging Spectrometer (MERIS) are compared with corresponding radiances from the Moderate Resolution Imaging Spectroradiometer (MODIS). MODIS is using an advanced on-board calibrating system making it ideal to be used as a reference sensor. The studied AVHRR sensor is carried by NOAA18, the AATSR and MERIS sensors are carried by ENVISAT and the selected MODIS sensor is carried by the Aqua satellite. MERIS is missing the channels at 1.6, 3.7, 11 and 12 micron while AVHRR on NOAA18 is missing the channel 1.6 micron. The technique used is based on simultaneous nadir observations (SNO). Here, different satellite measurements made over the same area within a time window of less than 10 minutes enables to estimate the sensor to sensor bias. This together with the fact that only the nadir pixels from each instrument are used enable the viewing geometries to be nearly identical. In the presentation the bias between the sensors for the time period 2007 - 2009 will be shown for both visible and infrared channels. The three year time period is long enough to indicate seasonal variations and bias changes over time. The long time period resulted in a total of 6200 globally distributed SNO points for each instrument ensuring statistical significance of the results. Since the AVHRR channel at 0.87 micron has a wider response function than the corresponding MODIS channel, a straight forward comparison between these two channels will not be correct. An attempt to correct for this difference, using the ratio between MODIS channel 17 (0.905 micron) and channel 18 (0.935 micron), will also be shown. This work is carried out within the framework of the ESA-CLOUD-CCI project.

  1. Bias Correction of high resolution MODIS Aerosol Optical Depth in urban areas using the Dragon AERONET Network

    NASA Astrophysics Data System (ADS)

    Malakar, N. K.; Atia, A.; Gross, B.; Moshary, F.; Ahmed, S. A.; Lary, D. J.

    2013-12-01

    Aerosol optical depth (AOD) is widely used parameter used to quantify aerosol abundance. Satellite retrievals of aerosols over land is fundamentally more complex than aerosol retrieval over oceans. Due to wide coverage and the extensive validation the Moderate Resolution Imaging Spectroradiometer (MODIS), on board the Terra and Aqua satellites is the workhorse instrument used to retrieve AOD from space. However, satellite algorithms of AOD are extremely complex and depends strongly on sun/view geometry, spectral surface albedo, aerosol model assumptions and surface heterogeneity. This issue becomes even more severe when considering the new MODIS 3 km aerosol retrieval products within version 6. To assess satellite retrievals of these high resolution 3 km products, we use the summer 2011 Dragon AERONET data to assess accuracy as well as major retrieval bias that can occur in MODIS measurements. In this study, we explore in detail the factors that can drive these biases statistically. As discussed above, our considers multiple conditions such as surface reflectivity at various wavelengths, solar and sensor zenith angles, the solar and sensor azimuth, scattering angles as well as meteorological factors and aerosol type (angstrom coefficient) etc which are used inputs are used to train neural network in regression mode to compensate for biases against the Dragon AERONET AOD values. In particular, we confirm the results of previous studies where the land cover (urban fraction) appears to be a strong factor in AOD bias and develop a NN estimator which includes land cover directly. The algorithm will be tested not only in the Baltimore/Washington area but assessed in the general North East US where urban biases in the NYC area have been previously identified.

  2. Estimate of the impact of absorbing aerosol over cloud on the MODIS retrievals of cloud optical thickness and effective radius using two independent retrievals of liquid water path

    NASA Astrophysics Data System (ADS)

    Wilcox, Eric M.; Harshvardhan, null; Platnick, Steven

    2009-03-01

    Two independent satellite retrievals of cloud liquid water path (LWP) from the NASA Aqua satellite are used to diagnose the impact of absorbing biomass burning aerosol overlaying boundary-layer marine water clouds on the Moderate Resolution Imaging Spectrometer (MODIS) retrievals of cloud optical thickness (?) and cloud droplet effective radius (re). In the MODIS retrieval over oceans, cloud reflectance in the 0.86-?m and 2.13-?m bands is used to simultaneously retrieve ? and re. A low bias in the MODIS ? retrieval may result from reductions in the 0.86-?m reflectance, which is only very weakly absorbed by clouds, owing to absorption by aerosols in cases where biomass burning aerosols occur above water clouds. MODIS LWP, derived from the product of the retrieved ? and re, is compared with LWP ocean retrievals from the Advanced Microwave Scanning Radiometer-EOS (AMSR-E), determined from cloud microwave emission that is transparent to aerosols. For the coastal Atlantic southern African region investigated in this study, a systematic difference between AMSR-E and MODIS LWP retrievals is found for stratocumulus clouds over three biomass burning months in 2005 and 2006 that is consistent with above-cloud absorbing aerosols. Biomass burning aerosol is detected using the ultraviolet aerosol index from the Ozone Monitoring Instrument (OMI) on the Aura satellite. The LWP difference (AMSR-E minus MODIS) increases both with increasing ? and increasing OMI aerosol index. During the biomass burning season the mean LWP difference is 14 g m-2, which is within the 15-20 g m-2 range of estimated uncertainties in instantaneous LWP retrievals. For samples with only low amounts of overlaying smoke (OMI AI ? 1) the difference is 9.4, suggesting that the impact of smoke aerosols on the mean MODIS LWP is 5.6 g m-2. Only for scenes with OMI aerosol index greater than 2 does the average LWP difference and the estimated bias in MODIS cloud optical thickness attributable to the impact of overlaying biomass burning aerosol exceed the instantaneous uncertainty in the retrievals.

  3. An Overview of MODIS Calibration and Characterization and Lessons Learned

    NASA Technical Reports Server (NTRS)

    Xiong, Xiaxiong; Wenny, B.; Barnes, W. L.; Salomonson, V. V.

    2009-01-01

    The Moderate Resolution Imaging Spectroradiometer (MODIS) is a key instrument for NASA's EOS missions. Two nearly identical copies have flown on the Terra and Aqua spacecraft for more than 9 years and 6 years since their launch in December 1999 and May 2002, respectively. MODIS observations and associated data products have been widely used by the science community and users worldwide for studies of Earth's system of land, oceans, and atmosphere. MODIS was developed based on the desire of the science community to extend and enhance heritage sensors' data records. It was designed with enhancements made over its heritage sensors in terms of its spectral, spatial, and radiometric characteristics. It is a cross-track scanning radiometer, that uses a two-sided scan mirror, collecting data in 36 spectral bands covering spectral regions of visible (VIS), near-infrared (NIR), short-wave infrared (SWIR), mid-wave infrared (MWIR), and long-wave infrared (LWIR). The VIS, NIR, and SWIR bands (bands 1-19 and 26), which make measurements of daytime surface reflected radiances, are referred to as the reflective solar bands (RSB). The MWIR and LWIR bands (20-25 and 27-36), which measure both the daytime and nighttime scene emissive radiances, are thus referred to as the thermal emissive bands (TEB). In this paper, we provide an overview of MODIS instrument calibration and characterization methodologies, activities, and results from pre-launch to post launch, with emphasis on the lessons learned from its design to on-orbit operation. Currently, both instruments are operated normally and all the on-orbit calibration activities are performed on a regular basis with some at slightly reduced frequencies. The TEB responses have been extremely stable with less than 0.3% change per year. For the RSB, the changes are wavelength and scan angle dependent with the largest changes in the VIS spectral bands. As both Terra and Aqua MODIS continue to operate beyond their prime missions, constant effort is still needed to maintain instrument and calibration and data product quality. This paper shows that the lessons from Terra MODIS design, test, and operation, have greatly benefitted Aqua MODIS. Because of this, Aqua MODIS overall performance is better than Terra MODIS. It is not surprising that lessons from MODIS calibration and characterization, from methodologies to on-orbit implementation, have also provided valuable information for the design and development of future earth observing missions/sensors, such as VHRS on the NPP and NPOESS, ABI on GOES-R, OLI on LDCM, and the reflective solar sensor on CLARREO.

  4. Characterization of MODIS solar diffuser on-orbit degradation

    NASA Astrophysics Data System (ADS)

    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.

  5. AQUA AMSR-E Sea Surface Temperature

    NASA Astrophysics Data System (ADS)

    Gentemann, C. L.

    2011-12-01

    NASA's AQUA satellite carries the JAXA's Advanced Microwave Scanning Radiometer - Earth Observing System (AMSR-E). The AQUA satellite was launched in May 2002 into a polar, sun-synchronous orbit at an altitude of 705 km, with a LECT of 1:30 AM/PM. AMSR-E has 12 channels corresponding to 6 frequencies; all except 23.8 GHz measure both vertical and horizontal polarizations. Geophysical retrievals of SST, wind speed, water vapor, cloud liquid water, and rain rates are calculated using a multi-stage linear regression algorithm derived through comprehensive radiative transfer model simulations. SST retrievals are prevented by rain, sun glint, near land emissions, and radio frequency interference due to geostationary satellite broadcasts. Since only a small number of retrievals are unsuccessful, almost complete global coverage is available daily. At high latitudes, where cloud cover regularly prevents infrared observations of SSTs, the microwave observations of SST provide a significant improvement to measurement capabilities. Validation of the datasets through comparison to the global drifting buoy networks yields mean biases of -0.02 K and standard deviations of 0.50 K. AMSR-E SSTs have been widely used for numerical weather prediction, ocean modeling, fisheries, and oceanographic research.

  6. MODIS imagery as a tool for synoptic water quality assessments in the southern California coastal ocean

    USGS Publications Warehouse

    Nezlin, N.P.; DiGiacomo, P.M.; Jones, B.H.; Reifel, K.M.; Warrick, J.A.; Johnson, S.C.; Mengel, M.J.

    2007-01-01

    The dynamics of rainstorm plumes in the coastal waters of southern California was studied during the Bight'03 Regional Water Quality Program surveys. Measurements of surface salinity and bacterial counts collected from research vessels were compared to MODIS-Aqua satellite imagery. The spectra of normalized water-leaving radiation (nLw) were different in plumes and ambient ocean waters, enabling plumes discrimination and plume area size assessments from remotely-sensed data. The plume/ocean nLw differences (i.e., plume optical signatures) were most evident during first days after the rainstorm over the San Pedro shelf and in the San Diego region and less evident in Santa Monica Bay, where suspended sediments concentration in discharged water was lower than in other regions. In the Ventura area, plumes contained more suspended sediments than in other regions, but the grid of ship-based stations covered only a small part of the freshwater plume and was insufficient to reveal the differences between the plume and ocean optical signatures. The accuracy of plume area assessments from satellite imagery was not high (77% on average), seemingly because of inexactitude in satellite data processing. Nevertheless, satellite imagery is a useful tool for the estimation of the extent of polluted plumes, which is hardly achievable by contact methods.

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

    PubMed Central

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

    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 showed that GEOV1 LAI is the most similar product with the LAI reference maps (R2 = 0.78 and RMSE = 0.59). The MODIS products performed well for biomes with low LAI values, but considerable uncertainty arose when the LAI was larger than 3. Terra + Aqua MODIS (R2 = 0.72 and RMSE = 0.68) was slightly more accurate than Terra MODIS (R2 = 0.57 and RMSE = 0.90) for producing slightly more successful observations. Both MODIS and GEOV1 products effectively followed the seasonal trajectory of the reference maps, and GEOV1 exhibited a smoother seasonal trajectory than MODIS. MODIS anomalies mainly occurred during summer and likely occurred because of surface reflectance uncertainty, shorter temporal resolutions and inconsistency between simulated and MODIS surface reflectances. This study suggests that further improvements of the MODIS LAI products should focus on finer algorithm inputs and improved seasonal variation modeling of MODIS observations. Future field work considering finer biome maps and better generation of LAI reference maps is still needed. PMID:25781509

  8. Reuse of the NASA LP DAAC MODIS Reprojection Tool (MRT) and the USGS Global Visualization Viewer (GloVis) for the Development of the LP DAAC Web-Based MODIS Reprojection Tool (MRTWeb)

    NASA Astrophysics Data System (ADS)

    Sohre, T.; Sauer, B.; Maiersperger, T.; Macie, M.; Miller, W.

    2007-12-01

    The Land Processes Distributed Active Archive Center (LP DAAC) was established as part of NASA's Earth Observing System (EOS) Data and Information System (EOSDIS) initiative to process, archive, and distribute land-related data collected by EOS sensors, thereby promoting the inter-disciplinary study and understanding of the integrated Earth system. The role of the LP DAAC includes the higher-level processing and distribution of ASTER data, and the distribution of MODIS land products derived from data acquired by the Terra and Aqua satellites. The LP DAAC anticipated that the community of land data users would need special software tools for handling the Level-3 MODIS land data products that would be distributed in HDF-EOS format and in the ISIN projection. The development of the MODIS Reprojection Tool (MRT) enabled users to read data files in HDF-EOS format (MODIS Level-2G, Level-3, and Level-4 land data products), specify a geographic subset or specific science data sets as input to processing, perform geographic transformation to a different coordinate system/cartographic projection, write the output to file formats other than HDF-EOS. Additional information regarding the MRT including links to download the software can be found at: http://lpdaac.usgs.gov/landdaac/tools/modis/index.asp. The LP DAAC has utilized the USGS Global Visualization Viewer (GloVis) as one method of data search and order. GloVis is a quick and easy online search and order tool for selected satellite data. The viewer allows user- friendly access to all available browse images from a number of Landsat data collections as well as ASTER, MODIS, and EO-1 data. Through a graphic map display, the user can select any area of interest and quickly view all available browse images within the USGS inventory for the specified location. GloVis can be run online at http://glovis.usgs.gov/ and the source code and be downloaded from: https://glovis.usgs.gov/distribution/. The LP DAAC saw an opportunity to reuse technologies from MRT and Glovis to develop a web-based tool that allows users to rapidly visualize tile-based MODIS data within a map context, navigate through time and space, select tiles of interest for processing, and then mosaic, subset, reproject, and select a data output format. This tool was developed utilizing a rapid development methodology that reused two existing technologies (MRT and GloVis). This paper will concentrate on the modification of reusable assets (specifically, MRT and GloVis) for reuse in a new system (MRTWeb). Lessons learned through this reuse experience will be highlighted.

  9. Tools for Accessing and Manipulating MODIS Snow & Sea Ice Products at the National Snow and Ice Data Center

    NASA Astrophysics Data System (ADS)

    Kaminski, M.; Khalsa, S.; Haran, T.; Wolfe, J.

    2004-12-01

    Snow and sea ice cover are some of the more important spatial features of the Earth's surface that can be readily measured from space. Moderate Resolution Imaging Spectroradiometer (MODIS) instruments onboard NASA's Terra and Aqua spacecraft collect spectral data that are used to routinely produce snow cover and sea ice products. With higher spatial and spectral resolution, the MODIS snow and ice products (including snow albedo and sea ice surface temperature) improve upon a long history of global coverage satellite-derived products that have been produced from polar-orbiting satellites since the early 1970s. Fully automated, quality controlled, daily global maps of snow cover and sea ice extent, produced at 500m, 1000m, and 0.05° spatial resolutions by the MODIS Land Team, are available from the National Snow and Ice Data Center (NSIDC) Distributed Active Archive Center (DAAC). The product suite will be further enhanced beginning mid-2005 with the inclusion of fractional snow cover in the daily product, addition of a daily snow product in a polar projection, and production of monthly climate modeling grid products for both snow and sea ice. Several tools are now available to streamline data acquisition and processing for users. Automated access to current data can be obtained through ingest subscriptions, data pool cache scripting, and a machine-to-machine gateway. Users can select data with targeted interfaces and the EOS Data Gateway, both with online reduced-resolution images to allow users to identify usable data prior to ordering. Integrated data manipulation tools provide subsetting, gridding, and resampling of images prior to downloading, minimizing the burden of data management by users. Collectively, the suite enables users to efficiently manage the large quantity of MODIS data available for regional and global studies.

  10. Photosynthetically Available Radiation at the Ocean Surface from Multiple Satellite Sensors: Uncertainties, Merging Issues, and Perspectives

    NASA Astrophysics Data System (ADS)

    Frouin, R. J.; Franz, B.

    2011-12-01

    A time series of photosynthetically available radiation at the ocean surface, 1997-present, has been generated from SeaWiFS, MODIS-Aqua, and MODIS-Terra data. Uncertainties are determined on daily, weekly, and monthly time scales from comparisons with in situ measurements. They are examined as a function of cloudiness. Individual instruments, combinations of two instruments, and three instruments are considered in the representation/assessment of performance. Spatial and temporal biases between estimates from one, two, or three instruments are corrected, resulting in a consistent time series for variability studies. Changes associated with inter-annual phenomena are presented. Including data from other satellite sensors, current and future, is discussed, as well as extending the methodology to UV-A and UV-B irradiance.

  11. NASA GES DISC DAAC Satellite Data for GIS

    NASA Technical Reports Server (NTRS)

    Nickless, Darryl; Leptoukh, Gregory; Morahan, Michael; Pollack, Nathan; Savtchenko, Andrey; Teng, William

    2005-01-01

    NASA's Goddard Earth Science (GES) Data and Information Services Center (DISC) Distributed Active Archive Center (DAAC) makes available a large and continually growing collection of spatially continuous global satellite observations of environmental parameters. These products include those from the MODIS (Moderate Resolution Imaging Spectroradiometer) on both Terra and Aqua platforms, and the Tropical Rainfall Measuring Mission (TRMM). These data products are well suited for use within Geographic Information Systems (GIS), as both backdrops to cartographic products as well as spatial analysis. However, data format, file size, and other issues have limited their widespread use by traditional GIS users. To address these data usability issues, the GES DISC DAAC recently updated tools and improved documentation of conversion procedures. In addition, the GES DISC DAAC has also been working with a major GIS software vendor to incorporate the ability to read the native Hierarchial Data Format (HDF), the format in which most of the NASA data is stored. The result is the enabling of GIS users to realize the benefit of GES DISC DAAC data without a substantial expenditure in resources to incorporate these data into their GIS. Several documents regarding the potential uses of GES DISC DAAC satellite data in GIS have recently been created. These show the combinations of concurrent data from different satellite products with traditional GIS vector products for given geographic areas. These map products include satellite imagery of Hurricane Isabel and the California wildfires, and can be viewed at http://daac.gsfc.nasa.gov/MODIS/GIS/.

  12. Regional representativity of AERONET observation sites during the biomass burning season in South America determined by correlation studies with MODIS Aerosol Optical Depth

    NASA Astrophysics Data System (ADS)

    Hoelzemann, Judith J.; Longo, Karla M.; Fonseca, Rafael M.; Do RosáRio, Nilton M. E.; Elbern, Hendrik; Freitas, Saulo R.; Pires, Carlos

    2009-07-01

    This paper presents an analysis of ground-based Aerosol Optical Depth (AOD) observations by the Aerosol Robotic Network (AERONET) in South America from 2001 to 2007 in comparison with the satellite AOD product of Moderate Resolution Imaging Spectroradiometer (MODIS), aboard TERRA and AQUA satellites. Data of 12 observation sites were used with primary interest in AERONET sites located in or downwind of areas with high biomass burning activity and with measurements available for the full time range. Fires cause the predominant carbonaceous aerosol emission signal during the dry season in South America and are therefore a special focus of this study. Interannual and seasonal behavior of the observed AOD at different sites were investigated, showing clear differences between purely fire and urban influenced sites. An intercomparison of AERONET and MODIS AOD annual correlations revealed that neither an interannual long-term trend may be observed nor that correlations differ significantly owing to different overpass times of TERRA and AQUA. Individual anisotropic representativity areas for each AERONET site were derived by correlating daily AOD of each site for all years with available individual MODIS AOD pixels gridded to 1° × 1°. Results showed that for many sites a good AOD correlation (R2 > 0.5) persists for large, often strongly anisotropic, areas. The climatological areas of common regional aerosol regimes often extend over several hundreds of kilometers, sometimes far across national boundaries. As a practical application, these strongly inhomogeneous and anisotropic areas of influence are being implemented in the tropospheric aerosol data assimilation system of the Coupled Chemistry-Aerosol-Tracer Transport Model coupled to the Brazilian Regional Atmospheric Modeling System (CCATT-BRAMS) at the Brazilian National Institute for Space Research (INPE). This new information promises an improved exploitation of local site sampling and, thus, chemical weather forecast.

  13. Estimation of surface-level PM concentration from satellite observation taking into account the aerosol vertical profiles and hygroscopicity.

    PubMed

    Kim, Kwanchul; Lee, Kwon H; Kim, Ji I; Noh, Youngmin; Shin, Dong H; Shin, Sung K; Lee, Dasom; Kim, Jhoon; Kim, Young J; Song, Chul H

    2016-01-01

    Surface-level PM10 distribution was estimated from the satellite aerosol optical depth (AOD) products, taking the account of vertical profiles and hygroscopicity of aerosols over Jeju, Korea during March 2008 and O