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|A statistical comparison of Indian MST radar and rawinsonde wind measurements
Reddy, K Krishna
Rao, D Narayana
Rao, P B
Jain, A R
Rama, G V
|Comparisons are made between horizontal wind measurements carried out using Indian MST radar at Gadanki (13.47°N, 79.18°E) and rawinsonde launched from SHAR centre, Sriharikota (13.7°N, 80.2°E). The spatial separation of MST radar and rawinsonde is about 90 km. The MST radar horizontal wind velocities are derived from Doppler wind measurements at zenith angle of 20° in two orthogonal planes. For the first time, using Indian MST radar in the tropics, extensive intercomparison results are presented up to an altitude of 18 km. Measurements over a period of 4 months (June September 1993) are considered, but the major part of the study involves a statistical analysis of data. The intercomparison was carried out using two methods. First, the comparison was made using the entire data obtained from both the instruments. Secondly, the comparison was repeated with data excluded whenever the instruments have large disagreements in excess of ±15 m/s. Comparison of hourly-averaged radar and rawinsonde wind measurements shows fairly good agreement between them. However, the present study reveals that radar-derived horizontal winds are underestimated when compared with rawinsonde values over the height range 3.6-18 km. The aspect sensitivity of radar echoes may cause for underestimation of horizontal wind. Comparison of horizontal wind measurements from the MST radar and the rawinsonde differs with a standard deviation of 2-2.5 m/s. Differences between the radar and balloon wind measurements can be attributed to a combination of three factors: (i) wind variability over the spatial separation between the two sites, (ii) temporal variability and (iii ) errors in the wind measurements. The present comparisons successfully demonstrate that both radar and rawinsonde give consistent wind measurements.
|0975-105X (Online); 0367-8393 (Print)
|Appears in Collections:
|IJRSP Vol.29(3) [June 2000]
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