Daily Land Surface Emissivity from Microwave 1993-2004


Land surface microwave emissivities were determined from the SSM/I brightness temperatures by removing the effects of the atmosphere, clouds, and rain (Aires et al., 2001) using ancillary data from ISCCP (Rossow and Schiffer, 1999) and the NCEP reanalysis (Kalnay et al., 1996). First, the cloud-free SSM/I observations are isolated using collocated visible/infrared satellite observations from ISCCP. The cloud-free atmospheric contribution is then calculated from temperature-humidity profiles from the NCEP reanalysis. Finally, surface skin temperature (TS) is taken from ISCCP (corrected for the original assumption of unit IR emissivity in the ISCCP product using surface-type-dependent IR emissivities) to determine the surface emissivities for the seven SSM/I channels. The calculated emissivities can be related to the intrinsic surface properties independent of atmospheric contributions or the variations of TS. The true emissivity is defined by the normalization of TB by the effective soil temperature corresponding to the contributions of all the surface layers of the ground weighted by their attenuation (Wigneron et al., 2008).


To access the dataset, download the Land Surface Emissivities


Each file is one global square map for one day for 12 years. For the documentation and a sample of matlab and fortran code to read the data click Here.

References

  • Aires, F., C. Prigent, W. B. Rossow, and M. Rothstein (2001), A new neural network approach including first guess for retrieval of atmospheric water vapor, cloud liquid water path, surface temperature, and emissivities over land from satellite microwave observations Journal of Geophysical Research-Atmospheres, 106(D14), 4887-14907.

  • Rossow, W. B., and R. A. Schiffer (1999), Advances in understanding clouds from ISCCP Bulletin of the American Meteorological Society,, 80(11), 2261-2287.

  • Kalnay, E., et al. (1996), The NCEP/NCAR 40-year reanalysis project,Bulletin of the American Meteorological Society,77(3), 437-471.

  • Wigneron, J. P., A. Chanzy, P. de Rosnay, C. Rudiger, and J. C. Calvet (2008), Estimating the effective soil temperature at L-band as a function of soil properties, IEEE T Geosci Remote, 46(3), 797-807.