2002 Annual

Wednesday, 16 January 2002
Rain and cloud observation by 95GHz cloud radar and 13.8GHz precipitation radar
Suginori Iwasaki, Frontier Observational Research System for Global Change, Yokohama, Japan; and H. Hanado, H. Horie, H. Kuroiwa, H. Kumagai, and H. Okamoto
Poster PDF (276.5 kB)
We show the synergy rain and clouds observation results by using 95GHz cloud radar and 13.8GHz precipitation radar at Kashima city, Japan, in November of 2000. And we also show the retrieved results of the raindrops size and the rain rate. The advantage of this study is to be able to observe the detail of the cloud with precipitation and to know the relation between clouds and rain because we use 95GHz cloud radar. We also report that the difference between Doppler velocity observed by 95GHz radar and that by 13.8GHz radar.

In the computations, we assume that the size distribution is the Marshall-Palmer distribution where we set the drop concentration N0 and the exponential slope b are parameters. We use Mie theory to calculate the backscattering cross section. The key of our calculations is that the radar reflectivity factors of rain by 95GHz cloud radar are different from those by 13.8GHz precipitation radar. That is, the backscattering of particles larger than 100 m is beyond Rayleigh scattering region for 95GHz radar, while that for 13.8GHz is still within Rayleigh region. Because the attenuation by 95GHz cloud radar is stronger than that by 13.8GHz precipitation radar, we can retrieve N0 and b and calculate the rain rate. We compare the rain rate retrieved by our computations and that by the typical Z-R relationships. We also calculate the melting layers and retrieve their sizing.

In the observational results, we show the results of Doppler velocity observations. Because 95GHz radar and 13.8GHz radar have different size sensitivity, Doppler velocity observed by 95GHz radar is different from that by 13.8GHz radar. We also report that the melting layers have very strong radar echo for 13.8GHz radar, that has been known as the bright band, while those are weak for 95GHz radar.

We will also report the synergy rain and clouds observations by using 95GHz cloud radar and 5.3GHz radar in this winter. This is the ship-borne observation in 138E-2N, tropical zone. We will also show the size of tropical raindrop and the rain rate retrieved by using two radar.

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