NUMBER 130

DATE: 05/10/94

Sector Processing Center (SPC):

During March, NOA, ESA, JMA, and CSU processed greater than 90% of A data into B1/B2 data. NOA reported processing more than 99% of A data into B1/B2 for February.

Normal operations for March were reported by NOA, ESA, JMA and CSU. No reports and B2 data have been received from AES for January, February and March.

AES reports that the cause of a persistent loss of the 0000 and 0300 UTC images is probably associated with the larger orbital motion of GOES-7 (station keeping fuel is no longer available), a condition that will persist until it is replaced by GOES-J.

Special Area Processing Center (SAPC):

No report received.

Satellite Calibration Center (SCC):

The SCC received AC data for September 93 through February 94 from GOES-7, for January 94 from NOAA-11, and for February and March from GMS-3, METEOSAT-3 and METEOSAT-5. BC data for GOES-7 for September 93 was sent to the GPC.

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.

Production of NOAA-12 (preliminary) B3 data is current.

Very small (few percent) adjustments to the normalization of NOAA-7 and NOAA-11 IR calibrations to NOAA-9 have been completed. Now that the reference polar orbiters have been re-calibrated, production of a new set of calibration tables (BT data) has commenced.

Production of GOES-7 (preliminary) B3 data is current. The processing of the UWS replacement B2 data has resumed.

Production of METEOSAT-3 (preliminary) B3 data is current. The processing of B3 data for May 92 through September 93 continues.

Production of METEOSAT-4 (preliminary) B3 data is complete. METEOSAT-5 production has not yet begun.

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

Production of all INSAT-1 (preliminary) B3 data has been completed.

Production of the ice/snow and TOVS correlative datasets is current; however, we are awaiting delivery of the sea ice data for 92 and 93.

Using two satellites viewing the same location simultaneously from different viewing zenith angles, we can test whether there are spurious angle dependences of the retrieved quantities. Tests of the old results showed weak dependences of retrieved surface temperatures over oceans and of cloud top temperatures and cloud amount. When divided by cloud type, some variations of optical thickness appear at lower values for upper level clouds. Some of the recent changes have been implemented to improve the radiative model. We find that the angle dependence for surface temperatures and cloud top temperatures were decreased slightly. The introduction of an ice phase model made only very small changes in the optical thickness dependences, but the validity of this new model is still being investigated.

The largest angle dependence is the systematic increase of cloud amount (in C1 data) with satellite viewing zenith angle. The most common explanation of this effect is that it is caused by geometric projection effects with broken clouds; however, another idea is that it is caused by increased frequency of detection of optically thin clouds. We have tested corrections based on both of these ideas (including all published schemes), as well as merely attempting an empirical removal of the effect and find no scheme that works for all cloud types. While each scheme has some beneficial effect on some cloud types, it makes the results for other types worse or has no effect on them. We also tried restricting the results to lower zenith angles, but this approach did not significantly reduce the effect although it significantly reduces the global coverage. A final explanation of this effect in the data will require much more extensive research; the reported quantities in Stage C1 data can serve as the basis of such a study. Therefore, no change will be made in the ISCCP processing.

ISCCP Central Archive (ICA):

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

The health of GMS-4, METEOSAT-3 (at 75 W), METEOSAT-5, GOES-7, NOAA-11 and NOAA-12 remained good. METEOSAT-5 has replaced METEOSAT-4. Investigation of the problems with METEOSAT-6 continues. GOES-8 was launched successfully on 12 April 94; however, it encountered some problems with its kick stage motor which turned out to be improper safety parameter settings. After some delay GOES-8 reached proper geostationary orbit and is now being checked; operations are planned to begin in October 94. The launch date for GOES-J, to replace GOES-7, is April 95. The Chinese Feng Yun-2 geostationary meteorological satellite was destroyed by an explosion on 2 April during a fueling test on the ground. There are active rumors that the long-awaited Russian geostationary satellite might be launched in June 94. The launch date for NOAA-J (to replace NOAA-11 after the loss of NOAA-I) has been set at 28 September 94. SCARAB on METEOR-3/7 is now routinely collecting data.

Stage B3: July 83 - June 91

Stage CD: July 83 - December 91

Stage C1: July 83 - June 91

Stage C2: July 83 - June 91

* Delivering GOES-7 B2 data for January, February and March 94 to the GPC.

* Delivering sea ice correlative data for 92 and 93 to GPC.

* Delivery backlog for B3 data = 27 months (with respect to planned schedule). B3 data for 96 months have been archived.

* Delivery backlog for C1/C2 data = 27 months (with respect to planned schedule). C1 data for 96 months have been archived.