NUMBER 46

DATE: 06/03/87

Sector Processing Center (SPC):

During April, ESA and JMA collectively processed greater than 94% of A data into B1 and/or B2 data.

Normal operations were reported by ESA and JMA. No reports were received from CSU and NOA.

ESA reported that a decontamination of the IR sensors of METEOSAT-2 was performed from 0900 GMT on 21 April 1987 until 0830 GMT on 23 April 1987. Data for this period is considered suspect; in addition, calibration information until 1800 GMT on 23 April 1987 is probably inaccurate.

Special Area Processing Center (SAPC):

No reports were received.

Satellite Calibration Center (SCC):

No report was received.

Global Processing Center (GPC):

The GPC continued to receive B1 and/or B2 data from JMA, ESA, CSU, and NOA and correlative data from NOAA/NESDIS in a routine manner.

Production of GOES-6 B3 data for the period from July 1984 through January 1985 has started. Installation of the quality inspection procedures into CLIPS will allow for QC to be performed during the production.

Final testing of the NOAA-7 to NOAA-9 calibration is being conducted. These tests include verification of the solar zenith angle corrections and repeat comparisons of the overlapping data with the NOAA-9 normalized to NOAA-7. Production of B3 data for selected months in 1985 is underway to provide a preliminary check of the NOAA-9 calibration stability for its first year of operations.

The ovelapping portions of the first C1 data provide an opportunity to compare the normalized calibrations of the geostationary satellites directly. This comparison, though still being studied, does not show any significant discrepancies for July 1983; the comparison results suggest an uncertainty in the normalizations of no more than 1-3% in visible radiances and 1-3 K in IR radiances. This cross-check procedure will be incorporated into the operational C data production to provide further monitoring of the radiance calibrations. These results will be reported at the Working Group meeting this month.

Copies of the first C1 tapes for July 1983 have been sent to about 50 scientists for comments and early study. In addition, copies have been sent to all members of the Working Group. Responses from these users over the next few months and discussions of the Working Group will be used to produce a revised version of the C1 format in August 1987.

Further study of the first C1 data suggests a number of changes that need to made in the production code and management system. These are as follows.

Detection step:

1. Implement regional intercomparison of clear IR radiances to remove some remaining cloud contamination (procedure already developed).

2. Implement regional intercomparison of clear VIS radiances to remove some remaining cloud contamination (procedure already developed).

3. Implement consistent count-to-quantity coversions that represent proper energy weighting and incorporate underflow/overflow values (procedure already developed).

4. Add use of snow/ice data in clear sky composite step.

5. Refine correction procedure for variable viewing geometry.

Radiation analysis step:

1. Implement proper treatment of small radiance values to prevent unnecessary loss of data (procedure already developed).

2. Implement calculations of new quantities: cloud albedo, cloud top location without correction for optical thickness, and retrieval error flags.

3. Refine angle treatment in IR analysis.

4. Refine correction procedure for cloud top location using optical thickness (based on overlapping data comparisons).

Statistics step:

1. Correct variance calculation (completed).

2. Correct "mixed" map cell treatment (completed).

3. Complete separation of visible channel effects on results.

4. Refine cloud classifications.

5. Refine "error" flags.

6. Revise C1 tape format and READ program.

Production system:

1. Re-organize disk storage to optimize I/O operations.

2. Refine data set naming conventions and standardize "global" data sets.

3. Standardize subroutines, especially those that READ, WRITE, MAP and DISPLAY the various data sets.

4. Implement "two-stream" processing system.

All of these remaining tasks will be discussed at the Working Group meeting this month. After resolution of the few remaining questions, the final version of the production software and the C1 tape format will be prepared by the end of the summer.

ISCCP Central Archive (ICA):

The ICA continued to receive B1 data from JMA, CSU, ESA, and NOA in a routine manner.

The health of GMS-3, METEOSAT-2, GOES-6, GOES-7, and NOAA-10 remained good. Channel 3 on the NOAA-9 MSU (Microwave Sounding Unit) has experienced some noise and unexpected changes in the space count value. TOVS data from NOAA-9 are still not available. Launch of NOAA-H is still scheduled for late October 1987. A saturation problem in the visible channel of the GOES-7 VAS has been reported; the effect on data quality has apparently been eliminated. GOES-6 reached its operational position at 135W on 28 April 1987.

Delivery of BC data for GOES-6 for October 1983 through July 1984 and for January 1985.

Delivery of NOAA-8 B2 data for March 1984 through June 1984.

Delivery of GMS B3 data for August 1983 through January 1985.

Normalization of NOAA-8 AVHRR to NOAA-7 and transfer of calibration from NOAA-7 to NOAA-9.

Obtaining NOAA-10 data over the Indian sector starting in December 1986.

Obtaining digital sea ice data for 1985 and 1986.

Arranging for the delivery of INSAT B1 data.