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Summary:

The Chang Special Sensor Microwave/Imager (SSM/I) Monthly Rainfall Indices were generated using the SSM/I brightness temperatures (TB) from the Defense Meteorological Satellite Program (DMSP) F8 and F11 satellites. The data set contains gridded ocean monthly total rainfall indices. The period of record for the data set is July, 1987 through December, 1995.

Table of Contents:

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2. Investigator(s):

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3. Theory of Measurements:

where V(i) is the radiometer output voltage, TA(i) (Kelvin) is the radiation temperature entering the feedhorn, and TN (Kelvin) is the radiometer noise temperature. The constants are c = detector constant, k = Boltzmann constant, B = receiver predetection bandwidth, and g = receiver gain. The subscript i denotes either a cold-space observation (i = C), a hot-load observation (i = H), or an Earth observation (i = E). The gain and noise temperature are assumed stable over the period of one scan, which is 1.9 seconds. That is to say, g and TN are assumed to be the same for the cold-space, hot-load, and Earth observations. The output voltage (V) is converted to counts (C) by applying a scaling factor (w) and a constant offset (P):

For each SSM/I scan, five cold counts and five hot counts are recorded for each channel. (Only 85 GHz observations are taken on the B-scans). The quantities C(C) and C(H) are found by averaging the five individual counts. The cold space antenna temperature TA(C) is set to 2.7 K for all channels. The hot reference antenna temperature is found from

where TO(H) and TO(P) are the physical temperatures of the hot load and the radiator plate facing the hot load. The small correction for the radiator plate is to account for radiative coupling between the hot load and the top plate of the rotating drum assembly which faces the hot load. There are three thermistors on the hot load and one on the radiator plate. The temperature T0(H) is found by averaging the three thermistor readings. Thus the A and B coefficients can be computed, and equation (3) can be inverted to recover the original values for the Earth-viewing counts C(E).

Additional Features

GES DISC DAAC Data Guide: Chang SSM/I Derived Monthly Rain Indices Data Set

Summary:

Table of Contents:

1. Data Set Overview:

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12. Application of the Data Set:

13. Future Modifications and Plans:

14. Software:

15. Data Access:

DAAC SEARCH AND ORDER SERVICES:

ANONYMOUS FTP:

16. Output Products and Availability:

17. References:

18. Glossary of Terms:

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Document URL:

GES DISC DAAC Data Guide:
Chang SSM/I Derived Monthly Rain Indices Data Set