Validation of TRMM rainfall products at Gadanki T. Narayana Rao NARL, Gadanki K. Nakamura, HyARC, Nagoya, Japan D. Narayana Rao, NARL, Gadanki National Atmospheric Research Laboratory (NARL), Gadanki

Diurnal variation National Atmospheric Research Laboratory (NARL), Gadanki

Comparison of vertical profile of Ze National Atmospheric Research Laboratory (NARL), Gadanki

Bright band statistics National Atmospheric Research Laboratory (NARL), Gadanki

Significant diurnal variation of rainfall is seen in SW monsoon season, whereas in the NE monsoon season it is negligible TRMM reproduces the diurnal variation of precipitation seen with the ORG Vertical profile of Ze given by profiler agrees well with that of TRMM below the bright band. The enhancement of Ze at BB is more in the case of profiler. Though, one can expect different Ze for different radars operating at different frequencies at high Z values (or at high rain rates), the difference seems to be more than one can expect. The bright band height variation during the course of the annul cycle is less than 250 m Bright band height is ~ 500 m below the 0 C isotherm level Height of the bright band as seen by TRMM matches with that of profiler Conclusions National Atmospheric Research Laboratory (NARL), Gadanki

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Selection of suitable cases for radar calibration

Profiler calibration

Bright band detection with a wind profiler The algorithm looks for a peak in vertical profiles of Z in the height range of km + A Doppler velocity difference of 1.5 m/s and a spectral width change of 0.3 m/s in 900 m (± 3 range bins from the Z peak). Several rain events are studied in detail to arrive at these thresholds.

BB detection in case studies - I

BB detection in case studies - II

Data TRMM – 2A25 5 years ( ) 1.3 GHz Wind profiler Precipitation in 3 rainy seasons Disdrometer 5 years ORG 5 years Errors: Random & Measurement errors, Systematic biases ?? Resolution: 1° x 1° and 2° x 2°, near nadir and full FOV For comparison : Surface rain (rainfall, rainrate, rain occurrence), diurnal variation of rainfall, vertical profiles and bright band statistics.

Location The comparison of rain parameters at the proposed site has its significance both technically and geographically. Technically – Profilers operating at VHF and UHF bands and other ground based precipitation measurements. Geographically – Gadanki is located close to the south-east coast of India, where the rainfall peaks in the northeast monsoon, in contrast to the rainfall in rest of India