Importance of Surface
Processes
Parameters such as the Normalized
Vegetation (NDVI), Land Surface Temperature (LST), and Sea Surface
Temperature (SST) are vital in understanding and modeling surface-atmosphere
interaction. First, it is vital to understand the complexities
involved in studies of surface characteristics (in particular,
remote sensing studies). The land surface can be made up of sand,
mud, swamp, grass, rock, etc. Each of these substances have different
spectral properties and appear differently in remotely sensed
data from aircraft and satellites. Therefore, it is necessary
to identify each of these substances and account for their impact
on the process or quantity being measured. With that in mind
we will explore the different parameters our group has investigated.
NDVI is constructed using
visible and near infrared data. Simply stated, chlorophyll, the
green substance that is responsible for photosynthesis, reflects
near infrared radiation more than it reflects visible radiation.
Thus, it is possible to form a mathematically relationship which
is high when green plants cover a pixel (digital picture element)
and low when no green plants are present. This is important in
meteorology because it determines the amount of energy going
into the Earths surface (as well as that being reflected)
to heat the atmosphere; i.e., when the NDVI is high LSTs are
cooler and therefore since the atmosphere is heated from below
it can be inferred that the air temperature is also cooler than
it would be given the same conditions with a lower NDVI. LST
is important because it determines the effective radiating temperature
of the Earths surface which controls the surface air temperature
as well as the clear sky Outgoing Longwave Radiation (OLR), which
is important in the energy balance of the Earth. Finally, SST,
in addition to its economic importance as a determining
factor in type of fish and seafood in a given area, it also impacts
the atmosphere through latent heat release during evaporation,
and it can determine seasonal and interannual variability of
the climate or a region or the globe (e.g., El Nino).
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Technical Contact: Dr. Gary J. Jedlovec (gary.jedlovec@msfc.nasa.gov)
Responsible Official: Dr. James L. Smoot (James.L.Smoot@nasa.gov)
Page Curator: Diane Samuelson (diane.samuelson@msfc.nasa.gov)
Last updated on: November 2, 1999 |