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| Titel |
Monthly oceanic rainfall based on METH techniques: DMSP SSM/I V6 and SSMIS continuity |
| VerfasserIn |
L. S. Chiu, S. Gao, D.-B. Shin, Y.-J. Cho, R. F. Adler, G. Huffman, D. Bolvin, E. Nelkin |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250071127
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| Zusammenfassung |
| As part of the Global Precipitation Climatology Project (GPCP), our group have been
producing oceanic rainfall over 2.5 and 5 degree boxes by applying the Microwave Emission
brightness Temperature (Tb) Histogram, or METH technique to the Special Sensor
Microwave Imager (SSM/I) data taken on board the Defense Meteorological Satellite
Program (DMSP) satellite series. Recently, the rainfall series have been updated
using the V6 SSM/I provided by RSS (Chiu and Chokngamwong., 2010). With
the demise of the F15 SSM/I sensor, we examine the use of the SSMIS series to
continue the DMSP time series. With its long duration, the DMSP satellite sensors
constitute a unique data set capable of producing microwave-based products for climate
studies. We compared the F13 SSM/I and F17 SSMIS for the period January 2008 –
September 2009. The METH technique matches the histogram of Tb (twice 19V
minus 22V) to a mixed-distribution of rain rates and estimates the parameters of
the rain rate distribution. Mathematical convergence of the matching procedure is
reached when a certain Chi-square threshold is reached. The important parameters are
the Tb of the non-raining pixels (To) and the freezing level (FL) of the grid box
considered. The sample size of the SSMIS is much larger than the SSM/I, hence the
convergence criteria is relaxed by changing the Chi-square threshold. Preliminary
results show a slight shift of the To (~0.8K). By adjusting To by a constant, the
domain average SSMIS rain rates and FL are computed to within 2% and 1% of the
SSM/I rain rates, respectively. Further investigation of the SSMIS METH rain rate
will involve the comparison of the 19V and 22V and fine tuning the Chi-square
parameter.
References: Chiu and Chokngamwong, 2010, J.Appl. Met. Clim, 49, 115-123; |
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