Rain effect variability analysis in Taiwan

Chi Huei Tseng, Kun Shan Chen, Chih Yuan Chu, Yu Chang Tzeng, Pay Liam Lin, J. C. Shi

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review


A two year observation (2002-2003) using two 2D optical distrometers at different locations were recorded. The DSD were measured and analyzed for different seasons under various rain rates. It follows that a relationship between rain rate and DSD was established. From statistical regression, it was also found that the DSD follows the Gamma distribution best in most cases. Long-term rain attenuation measurements using a Ka band (28GHz) CW system at vertical polarization were conducted in northern Taiwan. An optical rain gauge which has resolution of 0.01mm and can collect the rain rate every 5 seconds measured the rain rate at the same location. The attenuation due to rain can be estimated by calculating the extinction coefficient over all of the rain drops within the antenna beam volume. Two methods were used to estimate the extinction coefficient. First, assuming that the scattering mechanism follows the Mie scattering approximation, and the rain drops are all sphere. Second, using T-Matrix method and the oblateness of the rain drops vary from 1.0 to 0.8. Making use of the Gamma-distribution for DSD model, a semi-empirical rain attenuation model was then developed. To validate the model, we compared it with the measured data. For the purpose of cross referencing, we also compared it with the ITU-R and Crane models. The results show that the proposed model matched very well with in-situ measurement from a two-year data set. Both the Crane model and the ITU-R model were inadequate, as expected, for a correct interpretation of the accumulated measurement data producing overestimates.

Original languageEnglish
Title of host publication25th Anniversary IGARSS 2005
Subtitle of host publicationIEEE International Geoscience and Remote Sensing Symposium
Number of pages4
StatePublished - 2005
Event2005 IEEE International Geoscience and Remote Sensing Symposium, IGARSS 2005 - Seoul, Korea, Republic of
Duration: 25 Jul 200529 Jul 2005

Publication series

NameInternational Geoscience and Remote Sensing Symposium (IGARSS)


Conference2005 IEEE International Geoscience and Remote Sensing Symposium, IGARSS 2005
Country/TerritoryKorea, Republic of


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