ERBE data on the Mass Store A number of single-level monthly mean fields were archived for the Earth Radiation Budget Experiment (ERBE). There are many more fields available from the ERBE S-4 data product; however, only those variables most similar to standard GCM-derived fields have been accessed and archived. The data are in ``TYPEc = CCM1'' history tape format at both 2.5 dg and T42 resolutions. Note that the ``day'' parameter (ICP ``DAYSc'') actually refers to monthly means. Field Processor Name Units Net radiation NETD W /m^2 Clear sky net radiation NETCSD W /m^2 Solar insolation TSOLRDCS W /m^2 Outgoing longwave radiation MLWD W /m^2 Reflected shortwave radiation MSWD W /m^2 Albedo ALBD fraction Clear sky outgoing longwave radiation MLWCSD W /m^2 Clear sky reflected shortwave radiation MSWCSD W /m^2 Clear sky albedo ALBCSD fraction Climatologies for each month and field have been produced. All available months were used, so averages were made over four years of data (except January, which was made over three years, 1986--1988). No attempt has been made to correct for inconsistencies introduced into the data record (e.g., by the failure of scanners), and this should be kept in mind when using the climatological data. The mean fields have the same processor names and units as above, but they are in ``TYPEc = SAVTAV'' format at 2.5 dg and T42 resolution.
The missing data all occur for the Absorbed Solar Radiation (ASR) and thus net radiation near the delimiter of the incoming radiation where it is difficult to obtain an accurate albedo. To fill the missing data, we firstly took advantage of the fact that the areas missing varied from year to year and we formed a climatology of the available data on albedo. A least squares fitted first harmonic was then derived for each point, and the missing climatological mean values determined and these were used to fill in the missing albedo. Finally, a 9 point smoother was applied to the replacement data and to data within 2 grids of a replacement value. The ASR and net radiation were then derived. The mean annual cycle probably involves more than a single harmonic, but use of the least squares fitting approach with more than one harmonic could occasionally result in albedos for missing points that exceeded unity. Therefore the approach used is conservative, but it produces quite reasonable numbers. Because the missing points are weighted by small incoming radiation, the impact on the ASR is not very great, but it is desirable to do this step rather than treat the data as missing.
For the first two years of ERBE data, the global mean outgoing longwave radiation (OLR) mean was 233.9 W/m^2 but it jumped to 236.5 W/m^2 after the loss of NOAA 9. Presuming that the values with 3 satellites are superior, we have adjusted the OLR everywhere uniformly downward from February 1987 on, justifying this as a bias most likely arising from the diurnal cycle. The net imbalance in annual mean net radiation was initially 4.2 to 6.0 W/m^2, and after the first adjustment to OLR, this was corrected for by applying a decrease in the albedo uniformly such that the twelve month running mean radiation budget balances. At the beginning and end of the ERBE record, the twelve-month mean is one-sided rather than centered. Note that each month is adjusted separately, not the twelve-month mean. Consequently, the adjustment in the ASR is non-uniform, and instead is greatest where the radiation is largest, consistent with the view that the imbalance is most likely associated with sampling, especially of the diurnal cycle. Therefore, following these two fairly minor adjustments, the 12 month running mean net radiation for most months is close to, but not exactly zero. It ranges from -0.14 W/m^2 to +0.14 W/m^2. Real interannual variability in the net radiation is not accounted for.