Corrections to NOAA OLR Data

Delta represents the difference between the uncorrected and the corrected OLR anomalies between 30N and 30S. By corrected, we mean the OLR corrected anomalies of Waliser and Zhou, 1997, J. Climate, pages 2125-2146. To utilize the global NOAA OLR dataset, we apply the Waliser correction to the region between +/- 30 degrees, (through July 1996 only) and apply a tapered correction near +/- 30 degrees to smooth any discontinuities that might be introduced. The tapered correction is as follows: we correct the region between +/- 27.5 degrees latitude by adding delta (at respective latitudes) to the anomalies. At +/- 30 degrees, we add 2/3*delta(@30 deg.), and at +/- 32.5 degrees, we add 1/3*delta(30 deg.). There is no correction poleward of 32.5 deg.

Then, since there are a number of missing points near the poles, we have done a natural neighbor interpolation on the corrected data, using the applicable monthly climatological value from ERBE OLR at the poles. This data set was also regridded using Spherepack , to provide an extrapolated, corrected NOAA OLR dataset on a T63 grid, as well as on the original 2.5 degree grid.