NUMBER 91

DATE: 03/05/91

Sector Processing Center (SPC):

During January, NOA, ESA, AES and JMA processed greater than 98% of A data into B1/B2 data.

Normal operations were reported by NOA, AES and JMA. AES reported processing more than 95% of November and 99% of December A data into B1/B2 data.

ESA reported that MET-4 was the operational satellite for most of January with the exception of the period from 0900 UTC on 22 January through 0830 UTC on 25 January when MET-3 provided data.

AES reported resolution of the sporadic ingest "timeouts" which prematurely terminated images before 1500 UTC on 5 December; the problem was caused by a "slowly failing" demodulator.

Special Area Processing Center (SAPC):

No reports were received.

Satellite Calibration Center (SCC):

BC data for October 90 were sent to the GPC for GOES-7 and GMS-4.

Global Processing Center (GPC):

The GPC continued to receive B2 data, BC data and correlative data in a routine manner.

Production of NOAA-11 (preliminary) B3 data is current. The problem with the IR calibration was finally tracked down to an incompatibility between GPC processing software and changed spectral response tables sent by NOAA. In effect, this caused a 5% error in the calculated bandwidth of the IR channels which affected the nominal calibration. With this problem resolved, the Channel 4 brightness temperatures are normalized to NOAA-9 (and hence to NOAA-7) with a slope = 1.067 and intercept of -19.0K. NOAA-11 B3 data have been re-calibrated for October through December 88 and sent to the ICA.

Production of NOAA-10 (preliminary) B3 data is current. The sudden change in the VIS calibration of NOAA-10 in May 89 has been traced to a change of NOMINAL calibration by NOAA. This event is interesting for two reasons. First, their records indicate that this change occurred in late December 88, but the data tapes and calibration statistics show no change until late May 89. Second, this change occurred before an announced NOAA policy change to begin routine updates of calibration. No explanation of the apparent cessation of the long-term drift in the calibration is available. The IR bandwidth calculation error discovered for NOAA-11 also affects NOAA-10 data. Since this affects only the nominal calibration, the error was removed by our normalization of NOAA-10 to NOAA-9 (and hence to NOAA-7). Moreover, the correction to the nominal calibration of Channel 4 is simply the subtraction of 1.6K (to within 0.2K). Therefore, NOAA-10 B3 data will not be re-processed for the period December 86 through December 88 (this decision will be re-considered after checking the nominal calibration for the other IR channel). The correction and changed normalization coefficients will be introduced beginning with the January 89 B3 data. The new normalization coefficients are (for brightness temperatures): slope = 1.076, intercept = -21.9K. NOAA-10 B3 data have now been re-calibrated through April 89 and sent to the ICA.

Production of METEOSAT (preliminary) B3 data is current. METEOSAT B3 data have been re-calibrated for November and December 88 and sent to the ICA.

Production of GOES-7 (preliminary) B3 data is current.

Production of GOES-6 (preliminary) B3 data is completed. The last of the GOES-6 B3 data (November 88 through January 89) have been re-calibrated and sent to the ICA.

Production of GMS-4 (preliminary) B3 data is current.

Production of snow and sea ice correlative data has been completed for 89 and shipped to the ICA. Production of TOVS correlative data is current.

C1 data for July and August 87 have been completed and shipped to the ICA.

ISCCP Central Archive (ICA):

The ICA continued to receive B1 data from NOA, AES, ESA, and JMA and B3 and C data from the GPC in a routine manner.