From: Diane Stokes [mailto:dstokes@ncep.noaa.gov]
Sent: Wednesday, August 22, 2001 3:26 PM

The SST analysis currently used by the AVN is referred to as the daily
OI SST analysis.  It is constructed using Optimum Interpolation on a 1x1
degree grid.  Input data are ship and buoy reports, bias corrected AVHRR
satellite retrievals, and sea ice coverage.  The resulting SST best
represents a bulk temperature.

The 'daily' OI SST is based on a weekly analysis used for climate
studies, but runs every day using data from the previous seven days.
Both analyses are described in:

---Reynolds, R. W. and T. M. Smith, 1994: Improved global sea surface
temperature analyses. J. Climate, 7, 929-948.


Regarding comparisons with AVHRR, because this analysis is relatively
smooth, comparison of the OI SST with AVHRR data will show significant
small scale differences in the high-gradient regions.  Also, because we
apply a prelimary real-time correction to the satellite data relative to
ship and buoy data, one would also find large scale differences in
regions/times when the satellite data is biased.  Potential causes of
biases in the satellite data include contamination from atmospheric
aerosols (as caused by volcanic eruptions or Saharan dust), water vapor,
or instrumentation errors.