A5067953923- Atmospheric aerosols and clouds
- Atmospheric chemistry and aerosols
- Atmospheric Ozone and Climate
- Atmospheric and Environmental Gas Dynamics
- Calibration and Measurement Techniques
- Aeolian processes and effects
- Air Quality Monitoring and Forecasting
- Remote Sensing in Agriculture
- Fire effects on ecosystems
- Spacecraft Design and Technology
- Solar Radiation and Photovoltaics
- Meteorological Phenomena and Simulations
- Space exploration and regulation
- Air Quality and Health Impacts
- Planetary Science and Exploration
- Marine and coastal ecosystems
- Urban Heat Island Mitigation
- Precipitation Measurement and Analysis
- Geophysics and Gravity Measurements
- Impact of Light on Environment and Health
- Climate variability and models
- Solar and Space Plasma Dynamics
- Spacecraft and Cryogenic Technologies
- Graphite, nuclear technology, radiation studies
- Soil Moisture and Remote Sensing
University of Maryland, Baltimore County
2015-2024
Goddard Space Flight Center
2005-2021
University of Maryland, Baltimore
2013-2020
Earth System Science Interdisciplinary Center
2016-2020
Systems Technology (United States)
2014-2020
University of Maryland, College Park
2014-2020
Jet Propulsion Laboratory
1996-2010
Weizmann Institute of Science
2008
American Federation of State, County and Municipal Employees
2008
Radiation Biophysics Laboratory
2007
Abstract 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 (0.41–15 μm). These measurements are used to derive aerosol optical thickness size parameters over land ocean. products available include at three visible wavelengths, measure fraction attributed fine mode, several derived including reflected solar flux top atmosphere. Over ocean, provided seven...
Abstract. The twin Moderate resolution Imaging Spectroradiometer (MODIS) sensors have been flying on Terra since 2000 and Aqua 2002, creating an extensive data set of global Earth observations. Here, we introduce the Collection 6 (C6) algorithm to retrieve aerosol optical depth (AOD) size parameters from MODIS-observed spectral reflectance. While not a major overhaul previous 5 (C5) version, there are enough changes that significant impacts products their interpretation. C6 will be created...
Daily distribution of the aerosol optical thickness and columnar mass concentration will be derived over continents, from EOS moderate resolution imaging spectroradiometer (MODIS) using dark land targets. Dark covers are mainly vegetated areas soils observed in red blue channels; therefore method limited to moist parts continents (excluding water ice cover). After launch MODIS elevated concentrations, for example, biomass burning tropics or urban industrial midlatitudes, continuously...
Since first light in early 2000, operational global quantitative retrievals of aerosol properties over land have been made from Moderate Resolution Imaging Spectroradiometer (MODIS) observed spectral reflectance. These products continuously evaluated and validated, opportunities for improvements noted. We replaced the surface reflectance assumptions, set model optical properties, lookup table (LUT). This second‐generation algorithm performs a simultaneous inversion two visible (0.47 0.66 μ...
Abstract. NASA's MODIS sensors have been observing the Earth from polar orbit, Terra since early 2000 and Aqua mid 2002. We applied a consistent retrieval processing algorithm to both derive Collection 5 (C005) dark-target aerosol products over land. Here, we validate along-orbit Level 2 by comparing quality assured AERONET sunphotometer measurements at 300 sites. From 85 463 collocations, representing mutually cloud-free conditions, find that >66% (one standard deviation) of...
The Moderate Resolution Imaging Spectroradiometer (MODIS) is an Earth-viewing sensor that flies on the Earth Observing System Terra and Aqua satellites, launched in 1999 2002, respectively. MODIS scans a swath width of 2330 km sufficiently wide to provide nearly complete global coverage every two days from polar-orbiting, Sun-synchronous, platform at altitude 705 km. provides images 36 spectral bands between 0.415 14.235 /spl mu/m with spatial resolutions 250 m (two bands), 500 (five 1000...
The recently released Collection 5 Moderate Resolution Imaging Spectroradiometer (MODIS) aerosol products provide a consistent record of the Earth's system. Comparing with ground‐based AERONET observations optical depth (AOD) we find that MODIS estimate AOD to within expected accuracy more than 60% time over ocean and 72% land. This is similar previous results for better However, new collection introduces 0.015 offset between Terra Aqua global mean ocean, where none existed previously....
Aerosol optical depths (τ a ) are derived operationally for the first time from MODIS (Moderate Resolution Imaging Spectroradiometer) measurements over vegetated and partially land at 0.47 0.66 μm wavelengths. The extensive validation made during July – September 2000 encompasses 315 co‐located τ in space by AERONET (Aerosol Robotic Network) more than 30 sites. lack of East Asia, India Australia makes this unavailable those regions. aerosol retrievals, except coastal zones, found within...
A new technique for remote sensing of aerosol over the land and atmospheric correction Earth imagery is developed. It based on detection dark surface targets in blue red channels, as previous methods, but uses 2.1 /spl mu/m channel, instead 3.75 their detection. 2.1-/spl channel present ADEOS OCTS GLI planned EOS-MODIS EOSP, a similar 2.2-/spl Landsat TM. The advantage 3.75-/spl that it not affected by emitted radiation. transparent to most types (except dust) therefore can be used detect...
Urban air pollution and smoke from fires have been modeled to reduce cloud formation by absorbing sunlight, thereby cooling the surface heating atmosphere. Satellite data over Amazon region during biomass burning season showed that scattered cumulus cover was reduced 38%in clean conditions 0%for heavy (optical depth of 1.3). This response radiative effect reverses regional instantaneous forcing climate -28 watts per square meter in cloud-free +8 once reduction is accounted for.
Meteorological observations, in situ data, and satellite images of dust episodes were used already the 1970s to estimate that 100 Tg are transported from Africa over Atlantic Ocean every year between June August deposited Americas. Desert is a main source nutrients oceanic biota Amazon forest, but it deteriorates air quality, as shown for Florida. Dust affects Earth radiation budget, thus participating climate change feedback mechanisms. There an urgent need new tools quantitative evaluation...
As more information about global aerosol properties has become available from remotely sensed retrievals and in situ measurements, it is prudent to evaluate this new information, both on its own the context of satellite retrieval algorithms. Using climatology almucantur Aerosol Robotic Network (AERONET) Sun photometer sites, we perform cluster analysis determine type as a function location season. We find that three spherical‐derived types (describing fine‐sized dominated aerosol) one...
Clouds developing in a polluted environment tend to have more numerous but smaller droplets. This property may lead suppression of precipitation and longer cloud lifetime. Absorption incoming solar radiation by aerosols, however, can reduce the cover. The net aerosol effect on clouds is currently largest uncertainty evaluating climate forcing. Using large statistics 1-km resolution MODIS (Moderate Resolution Imaging Spectroradiometer) satellite data, we study shallow water clouds, separately...
Clouds and precipitation play crucial roles in the Earth's energy balance, global atmospheric circulation availability of fresh water. Aerosols may modify cloud properties formation by modifying concentration size droplets, consequently strength convection, height glaciation levels thus affecting patterns. Here we evaluate aerosol effect on clouds, using large statistics daily satellite data over North Atlantic Ocean. We found a strong correlation between presence aerosols structural...
With the launch of MODIS sensor on Terra spacecraft, new data sets global distribution and properties aerosol are being retrieved, need to be validated analyzed. A system has been put in place generate spatial statistics (mean, standard deviation, direction rate variation, correlation coefficient) parameters over more than 100 validation sites spread around globe. Corresponding also computed from temporal subsets AERONET‐derived data. The means deviations identical AERONET compared....
[1] An aerosol component of a new multiangle implementation atmospheric correction (MAIAC) algorithm is presented. MAIAC generic developed for the Moderate Resolution Imaging Spectroradiometer (MODIS), which performs retrievals and over both dark vegetated surfaces bright deserts based on time series analysis image-based processing. The look-up tables explicitly include surface bidirectional reflectance. derives spectral regression coefficient (SRC) relating reflectance in blue (0.47 μm)...
The NASA moderate resolution imaging spectroradiometer (MODIS) instrument will provide a global and improved source of information for the study land surfaces with spatial up to 250 m. Prior derivation various biophysical parameters based on surface reflectances, top atmosphere signals need be radiometrically calibrated corrected atmospheric effects. present paper describes in detail state art techniques that used correction MODIS bands 1 through 7, centered at 648, 858, 470, 555, 1240,...
The effect of anthropogenic aerosols on clouds is one the most important and least understood aspects human-induced climate change. Small changes in amount cloud coverage can produce a forcing equivalent magnitude opposite sign to that caused by greenhouse gases, height shift from cooling warming. Focusing Amazon, we show smooth transition between two opposing effects clouds: microphysical radiative. We how feedback optical properties fraction modify aerosol forcing, changing total radiative...
Polarimetry is one of the most promising types remote sensing for improved characterization atmospheric aerosol. Indeed, aerosol particles constitute a highly variable component characterized by large number parameters describing particle sizes, morphologies (including shape and internal structure), absorption scattering properties, amounts, horizontal vertical distribution, etc. Reliable monitoring all these very challenging, therefore effects on climate environment are considered to be...
The MODerate resolution Imaging Spectroradiometer (MODIS) algorithm for determining aerosol characteristics over ocean is performing within expected accuracy. A two‐month data set of MODIS retrievals co‐located with observations from the AErosol RObotic NETwork (AERONET) ground‐based sunphotometer network provides necessary validation. Spectral radiation measured by (in range 550–2100 nm) used to retrieve optical thickness, effective particle radius and ratio between submicron micron size...
Abstract. After more than a decade of producing nominal 10 km aerosol product based on the dark target method, MODerate resolution Imaging Spectroradiometer (MODIS) team will be releasing 3 as part their Collection 6 release. The new differs from original only in manner which reflectance pixels are ingested, organized and selected by algorithm. Overall, closely mirrors product. However, finer is able to retrieve over ocean closer islands coastlines, better resolve fine features such smoke...
Abstract The productivity of the Amazon rainforest is constrained by availability nutrients, in particular phosphorus (P). Deposition long‐range transported African dust recognized as a potentially important but poorly quantified source phosphorus. This study provides first multiyear satellite‐based estimate deposition into Basin using three‐dimensional (3‐D) aerosol measurements over 2007–2013 from Cloud‐Aerosol Lidar with Orthogonal Polarization (CALIOP). 7 year average estimated to be 28...
The detection of dark, dense vegetation is an important step in the remote sensing aerosol loading. Current methods that employ red (0.64 /spl mu/m) and near-IR (0.84 regions are unsatisfactory presence aerosols scene distorts apparent reflectance visible ranges spectrum. mid-IR spectral region also sensitive to due absorption liquid water foliage, but not most (except for dust). Therefore, channels on AVHRR EOS-MODIS (e.g., 3.75 mu/m or 3.95 channels) have a unique potential vegetation,...
Cloud and aerosols interact form a complex system leading to high uncertainty in understanding climate change. To simplify this non‐linear it is customary distinguish between “cloudy” “cloud‐free” areas measure them separately. However, we find that clouds are surrounded by “twilight zone” – belt of forming evaporating cloud fragments hydrated extending tens kilometers from the into so‐called cloud‐free zone. The gradual transition cloudy dry atmosphere proportional aerosol loading,...