3. Research Capability
SMCD's Branches exploit a number of science and technology areas in fulfilling its broad mission of transforming raw satellite observations into the accurate, quantitative information that is needed to predict weather, monitor climate, and detect environmental hazards. The science and technology area of each of SMCD's branches are described here.
Environmental Monitoring Branch
As numerical weather prediction models become more sophisticated and improve their treatment of surface atmosphere interactions, the need for good measurements of surface conditions - snow cover, ice cover, vegetation conditions, surface radiation budget, and precipitation - is accelerating. One of the major uncertainties in projections of climate change is the role of atmospheric aerosols, and data are urgently needed on their global distribution, characteristics, and time trends.
Surface condition products, Earth Radiation Budget, and aerosol products are the responsibility of the Environmental Monitoring Branch. The Branch faces the challenge of developing high quality products to meet these challenging demands as well as others in an ever-increasing range of applications for its weather, climate, and hazards products. The Environmental Monitoring Branch also faces the challenge - as does the rest of SMCD - of preparing for the entirely new suite of instruments on NPOESS.
Surface vegetation conditions are important for monitoring drought, providing boundary conditions for weather prediction models, forecasting agricultural yields, monitoring land surface changes, and understanding the global carbon cycle. Over the last few decades, SMCD researchers have led the development and application of vegetation products, primarily from the AVHRR instrument.
Among the products developed by SMCD scientists are the: Normalized Difference Vegetation Index (NDVI), the two channel AVHRR "greenness" index that serves as the basis for all other vegetation products; green vegetation fraction, defined as the fractional area of active vegetation per unit horizontal area; Vegetation Condition Index (VCI), a measure of drought conditions; and FR, a fire risk index.
Earth Radiation Budget and Aerosols
The Earth's radiation budget (ERB) represents the balance between incoming energy from the Sun and outgoing longwave (OLR) and reflected (shortwave) energy from the Earth (planetary albedo). Changes in the radiative energy balance of the Earth-atmosphere system (caused, for example, by increasing amounts of carbon dioxide and aerosols) can cause long-term changes in climate. Satellites orbiting above the atmosphere are ideal for measuring the radiative energy streams into and out of Earth-atmosphere system. Over the years they have contributed to narrowing the uncertainty in the planetary albedo and outgoing longwave radiation, and improved our understanding of the energy budget.
SMCD scientists developed the original algorithm for estimating OLR from POES IR imagers back in the early 1970s. The OLR data set is now over three decades long, and has played a crucial role in both real-time monitoring and retrospective studies of El Nino Southern Oscillation (ENSO) events. SMCD personnel are actively involved in deriving traditional and new ERB parameters, and in improving the algorithms used to estimate them.
The important role of aerosols in shaping the environment and climate is now well recognized as well as the fact that current estimates of aerosol radiative forcing represent one of the largest uncertainties in assessing global climate change. This recognition is reflected in various research plans, such as the 2001 US Climate Change Research Initiative, which identified the "Development of reliable representations of climate forcing resulting from atmospheric aerosol" as one of its top priority goals. Atmospheric aerosols affect the radiation budget by either reflecting solar radiation back to space, absorbing long-wave radiation, or affecting cloud properties - which would also influence the ERB. In addition, increased levels of aerosols adversely affect human health. Monitoring also provides information, among others, for visibility analysis, validation of aerosol transport models and for aerosol-correction of sea surface temperature. Satellite-derived aerosol data should also improve regional and global assessment and forecast of air quality.
SMCD scientists developed the AVHRR aerosol product that has been used to monitor global aerosol distributions and the dust ejected into the atmosphere by intense volcanic eruptions, such as Mount Pinatubo in 1991. They continue to improve our capability to measure aerosols from satellite observations.
Data, algorithms, and images presented on STAR websites are intended for experimental use only and are not supported on an operational basis. More information