‘Down‐to‐Earth’ modelling of equivalent surface precipitation using multisource data and radar

• Published in: Quarterly journal of the Royal Meteorological Society Vol. 131; no. 607; pp. 1093 - 1112
• Main Authors: Michelson, D. B., Jones, C. G., Landelius, T., Collier, C. G., Haase, G., Heen, M.
• Format: Journal Article
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 01.04.2005; Wiley
• Subjects: Cloud physics; Earth, ocean, space; Evaporation; Exact sciences and technology; External geophysics; Geophysics. Techniques, methods, instrumentation and models; Meteorology; Vertical reflectivity profile; Water in the atmosphere (humidity, clouds, evaporation, precipitation); Meteorological observation; rainfall; Weather forecast; atmospheric precipitation; Bias; Random error; digital simulation; Cloud physics; Cloud physics Evaporation Vertical reflectivity profile; Radar observation; Observation data; Numerical forecast; Reflectance
• ISSN: 0035-9009; 1477-870X
• DOI: 10.1256/qj.03.203

The estimation of surface rainfall from reflectivity data derived from weather radar has been much studied over many years. It is now clear that central to this problem is the adjustment of these data for the impacts of vertical variations in the reflectivity. In this paper a new procedure (known as Down‐to‐Earth, DTE) is proposed and tested for combining radar measurements aloft with information from a numerical weather‐prediction (NWP) model and an analysis system. The procedure involves the exploitation of moist cloud physics in an attempt to account for physical processes impacting on precipitation during its descent from the height of radar echo measurements to the surface. The application of DTE leads to increased underestimation in the radar measurements compared to precipitation gauge observations at short and intermediate radar ranges (0–120 km), but is successful at reducing the bias at further ranges. However the application of DTE does not lead to significant decreases in the random error of the surface rain rate estimate. No improvement is made when attempting to account for the precipitation phase measured by radar. It is concluded that further work on radar data quality control, along with improvements to the NWP model, are essential to improve upon results using such a physically based procedure. Copyright © 2005 Royal Meteorological Society