Forecast of heavy rainfall in West of Iran According to Weather Radar Estimates Using the Z-R method

Safarpour, Farshad; Khoshhal Dastjerdi, Javad; Masoodian, Abolfazl

doi:10.22111/jneh.2018.24964.1403

Forecast of heavy rainfall in West of Iran According to Weather Radar Estimates Using the Z-R method

Document Type : Research Article

Authors

¹ Ph.D student of Climatology, Isfahan University, Isfahan, Iran

² Associate Professor of Climatology, Isfahan University, Isfahan, Iran

³ Professor of Climatology, Isfahan University, Isfahan, Iran

10.22111/jneh.2018.24964.1403

Abstract

The amount of precipitation measured by the radar is different from the amount of precipitation received on the ground. This difference has many causes, some of which are related to the nature of the radar and others to the climate of each region. As a result, radar data needs to be corrected for radar data based on terrestrial data to determine the amount of ground-level rainfall received from the radar data. Weather radar used for estimation of rain in the large areas. The relationship between rain and reflectivity radar is exponential Z = aR^b. Radar estimated rainfall amount is incorrect if the coefficients of this model are wrong. Drop size and distribution of rainfall is Effective on the coefficient of this model. The change in the coefficients of this model is very high. In this study, to calibrate radar data, rain from 2 to 3 December 2016 and 11 to 13 February 2018 at the stations, Kermanshah, Eslamabad, Sarpol, Ghasre Shirin, Harsin, Javanroud, Tazabad, Songhor, Ravansar, Ghilan Gharb and Soumar at distance of 30 to 100 kilometers from Kermanshah’s radar are investigated. In the first rain, using soft Rainbow for each of the stations and radar beam elevation angle optimization and correction factors relating to the extraction station, respectively. With this relationship, the radar rainfall estimates from 31 percent to 96 percent Increased and the average total rainfall from 8.9 to 32.4 millimeter increased an average radar rainfall estimated only 1 millimeter less than actual rain by gauge. In the second rain, using data from all stations, only one equation and correction factors were obtained. The results rainfall radar will be accepted at this stage, good approximation, and the average estimate rainfall radar from 9.6 to 23.5 millimeter increased those 4 millimeters less than the actual amount by gauge. If radar coefficients are corrected correctly for different areas, precipitation can be predicted and prevented from occurring unexpected events.

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References

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