The impact of wind drift on the utility of very high spatial resolution radar data over urban areas

Weather radars are capable of estimating rainfall with resolutions of a hundred metres or so and less than one minute. Re-analysis of published results indicate that reducing the spatial resolution to 1km is only likely to give additional benefit if allowance is made for the drift of the rainfall between the radar beam and the ground. The vertical and horizontal profiles of wind are important in this context. On balance, it is concluded that the use of 1-2km resolution for large urban catchments is appropriate if wind profile information is not available. However, use of resolutions higher than 1km demands that wind drift be taken into account. If this is not possible, then techniques other than radar should be used to make measurements over catchments less than or equal to 1km(2). (C) 1999 Elsevier Science Ltd. All rights reserved.