A5079095933- Remote Sensing in Agriculture
- Plant Water Relations and Carbon Dynamics
- Atmospheric and Environmental Gas Dynamics
- Land Use and Ecosystem Services
- Climate variability and models
- Remote Sensing and LiDAR Applications
- Viral Infections and Vectors
- Remote Sensing and Land Use
- African Botany and Ecology Studies
- Fire effects on ecosystems
- Conservation, Biodiversity, and Resource Management
- Species Distribution and Climate Change
- Urban Heat Island Mitigation
- Viral Infections and Outbreaks Research
- Ecology and Vegetation Dynamics Studies
- Rangeland Management and Livestock Ecology
- Rangeland and Wildlife Management
- Soil Moisture and Remote Sensing
- Leaf Properties and Growth Measurement
- Energy and Environment Impacts
- Meteorological Phenomena and Simulations
- Agriculture and Rural Development Research
- Mosquito-borne diseases and control
- Remote-Sensing Image Classification
- Atmospheric chemistry and aerosols
Goddard Space Flight Center
2015-2024
Western University
2024
Science Systems and Applications (United States)
2004-2023
University of Copenhagen
2023
National Aeronautics and Space Administration
1996-2021
NASA Earth Science
2021
Science Applications International Corporation (United States)
2019
University of Illinois Urbana-Champaign
2014
University of Arizona
2014
Oregon State University
2012
Recent climatic changes have enhanced plant growth in northern mid-latitudes and high latitudes. However, a comprehensive analysis of the impact global on vegetation productivity has not before been expressed context variable limiting factors to growth. We present investigation responses by analyzing 18 years (1982 1999) both data satellite observations activity. Our results indicate that climate eased several critical constraints growth, such net primary production increased 6% (3.4...
Daily daytime Advanced Very High Resolution Radiometer (AVHRR) 4‐km global area coverage data have been processed to produce a Normalized Difference Vegetation Index (NDVI) 8‐km equal‐area dataset from July 1981 through December 2004 for all continents except Antarctica. New features of this include bimonthly composites, NOAA‐9 descending node August 1994 January 1995, volcanic stratospheric aerosol correction 1982–1984 and 1991–1993, NDVI normalization using empirical mode...
Landsat satellite imagery covering the entire forested portion of Brazilian Amazon Basin was used to measure, for 1978 and 1988, deforestation, fragmented forest, defined as areas less than 100 square kilometers surrounded by edge effects 1 kilometer into forest from adjacent deforestation. Tropical deforestation increased 78,000 in 230,000 1988 while tropical habitat, severely affected with respect biological diversity, 208,000 588,000 kilometers. Although this rate is lower previous...
Abstract Leaf structure and function are shown to result in distinctive variations the absorption reflection of solar radiation from plant canopies. The leaf properties that determine radiation-interception characteristics canopies directly linked photosynthesis, stomatal resistance evapotran-spiration can be inferred measurements reflected energy. effects off-nadir viewing atmospheric constituents, coupled with need measure changing surface conditions, emphasize for multitemporal if primary...
Abstract Coarse spatial resolution, high temporal frequency satellite data from the NOAA/AVHRR system are presented to demonstrate their utility for monitoring vegetation seasonal dynamics. The techniques processing and analysing outlined examples given selected applications at a range of scales. Normalized difference index images entire globe continents Africa, South America south-east Asia, with descriptions dynamics major formations as portrayed by transformed AVHRR data. Monitoring...
Data from the advanced very-high-resolution radiometer sensor on National Oceanic and Atmospheric Administration's operational series of meteorological satellites were used to classify land cover monitor vegetation dynamics for Africa over a 19-month period. There was correspondence between seasonal variations in density extent green-leaf patterns rainfall associated with movement Intertropical Convergence Zone. Regional variations, such as 1983 drought Sahel westem Africa, observed....
The global parameter fields used in the revised Simple Biosphere Model (SiB2) of Sellers et al. are reviewed. most important innovation over earlier SiB1 set Dorman and is use satellite data to specify time-varying phonological properties FPAR, leaf area index. canopy greenness fraction. This was done by processing a monthly 1° normalized difference vegetation index (NDVI) dataset obtained farm Advanced Very High Resolution Radiometer red near-infrared data. Corrections were applied source...
China has experienced rapid urbanization and dramatic economic growth since its reform process started in late 1978. In this article, we present evidence for a significant effect on climate based analysis of impacts land-use changes surface temperature southeast China, where occurred. Our estimated warming mean 0.05°C per decade attributable to is much larger than previous estimates other periods locations. The spatial pattern magnitude our estimate are consistent with those characterized by...
Data from polar-orbiting meteorological satellites have been used to determine the extent of Sahara Desert and document its interannual variation 1980 1990. The ranged 8,633,000 square kilometers in 9,982,000 1984. greatest annual north-south latitudinal movement southern Saharan boundary was 110 1984 1985 resulted a decrease desert area 724,000 kilometers.
Tropical deforestation is a key contributor to species extinction and climate change, yet the extent of tropical forests their rate destruction degradation through fragmentation remain poorly known. Madagascar's are among most biologically rich unique in world but, spite longstanding concern about destruction, past estimates forest cover have varied widely. Analysis aerial photographs (c. 1953) Landsat images 1973, c. 1990 2000) indicates that decreased by almost 40% from 1950s 2000, with...
The terrestrial carbon sink, as of yet unidentified, represents 15–30% annual global emissions from fossil fuels and industrial activities. Some the missing is sequestered in vegetation biomass and, under Kyoto Protocol United Nations Framework Convention on Climate Change, industrialized nations can use certain forest sinks to meet their greenhouse gas reduction commitments. Therefore, we analyzed 19 years data remote-sensing spacecraft inventories identify size location such sinks....
All known Rift Valley fever virus outbreaks in East Africa from 1950 to May 1998, and probably earlier, followed periods of abnormally high rainfall. Analysis this record Pacific Indian Ocean sea surface temperature anomalies, coupled with satellite normalized difference vegetation index data, shows that prediction may be made up 5 months advance Africa. Concurrent near–real-time monitoring data identify actual affected areas.
The Sea-viewing Wide Field-of-view Sensor (SeaWiFS) provides global monthly measurements of both oceanic phytoplankton chlorophyll biomass and light harvesting by land plants. These allowed the comparison simultaneous ocean net primary production (NPP) responses to a major El Niño La Niña transition. Between September 1997 August 2000, biospheric NPP varied 6 petagrams carbon per year (from 111 117 year). Increases in were pronounced tropical regions where Niño–Southern Oscillation (ENSO)...
The role of naturally varying vegetation in influencing the climate variability West African Sahel is explored a coupled atmosphere-land-vegetation model. rainfall influenced by sea-surface temperature variations oceans. Land-surface feedback found to increase this both on interannual and interdecadal time scales. Interactive enhances variation substantially but can reduce year-to-year because phase lag introduced relatively slow adjustment time. Variations accompany changes rainfall,...
Many assumptions have been made about the nature and character of desertification in West Africa. This paper examines history this issue, reviews current state our knowledge concerning meteorological aspects desertification, presents results a select group analyses related to question. The common notion is an advancing “desert,” generally irreversible anthropogenic process. process has linked increased surface albedo, dust generation, reduced productivity land. study demonstrates that there...
The physiological response of terrestrial vegetation when directly exposed to an increase in atmospheric carbon dioxide (CO 2 ) concentration could result warming over the continents addition that due conventional CO “greenhouse effect.” Results from a coupled biosphere-atmosphere model (SiB2-GCM) indicate that, for doubled conditions, evapotranspiration will drop and air temperature tropical continents, amplifying changes resulting radiative effects. range responses surface uptake increased...