The Quantification and Correction of Wind-Induced Precipitation Measurement Errors
John Kochendorfer1, Roy Rasmussen2, Mareile Wolff3, Bruce Baker1, Mark E. Hall1, Tilden Meyers1, Scott Landolt2, Al Jachcik2, Ketil Isaksen3, Ragnar Brækkan3, and Ronald Leeper4,51ARL/Atmospheric Turbulence and Diffusion Division, National Oceanic and Atmospheric Association, Oak Ridge, TN, 37830, US 2National Center s for Atmospheric Research, Boulder, 80305, US 3Norwegian Meteorological Institute, Oslo, 0313, Norway 4N Carolina State Univ., Cooperative Inst of Climate and Satellites, Asheville, 28801 US 5National Center for Environmental Information, National Oceanic and Atmospheric Association, Asheville, 28801 US
Received: 16 Aug 2016 – Accepted for review: 08 Sep 2016 – Discussion started: 09 Sep 2016
Abstract. Hydrologic measurements are becoming increasingly important for both the short and long term management of water resources. Of all the terms in the hydrologic budget, precipitation is the typically most important input. However, measurements of precipitation are still subject to large errors and biases. For example, a high-quality but unshielded weighing precipitation gauge can collect less than 50 % of the actual amount of solid precipitation when wind speeds exceed 5 ms−1. Using results from two different precipitation testbeds, such errors have been assessed for unshielded weighing gauges and for four of the most common windshields currently in use. Functions used to correct wind-induced undercatch were developed and tested. In addition, corrections for the single Altar weighing gauge were developed using the combined results of two separate sites, one of which was in Norway and other in the US. In general the results indicate that corrections described as a function of air temperature and wind speed effectively remove the undercatch bias that affects such precipitation measurements. In addition, a single ‘universal’ function developed for the single Altar gauges effectively removed the bias at both sites, with the bias at the US site improved from −12 % to 0 %, and the bias at the Norwegian site improved from −27 % to −3 %. These correction functions require only wind speed and air temperature, and were developed for use in national and local precipitation networks, hydrological monitoring, roadway and airport safety work, and climate change research. The techniques used to develop and test these transfer functions at more than one site can also be used for other more comprehensive studies, such as the WMO Solid Precipitation Intercomparison Experiment.
Kochendorfer, J., Rasmussen, R., Wolff, M., Baker, B., Hall, M. E., Meyers, T., Landolt, S., Jachcik, A., Isaksen, K., Brækkan, R., and Leeper, R.: The Quantification and Correction of Wind-Induced Precipitation Measurement Errors, Hydrol. Earth Syst. Sci. Discuss., doi:10.5194/hess-2016-415, in review, 2016.