Advances in Geosciences www.adv-geosci.net 1680-7340 1680-7359 25 Precipitation: Measurement, Climatology, Remote Sensing, and Modeling (EGU Session 2009) 2010 10.5194/adgeo-25-11-2010 http://www.adv-geosci.net/25/11/2010/ http://www.adv-geosci.net/25/11/2010/adgeo-25-11-2010.html http://www.adv-geosci.net/25/11/2010/adgeo-25-11-2010.pdf 11 15 2010-03-08 Undercatch of tipping-bucket gauges in high rain rate events C. E. Duchon cduchon@ou.edu C. J. Biddle University of Oklahoma, Norman, Oklahoma, USA We have investigated differences in rainfall accumulations for seven high rain rate events from three gauges: a Geonor T-200B vibrating-wire weighing gauge and two MetOne tipping-bucket gauges. The Geonor gauge and one tipping-bucket gauge are located in a pit so that their collection orifices are at ground level. Thus their measured rainfall accumulations are minimally affected by wind speed. The other tipping-bucket gauge is located 105 m from the pit and is surrounded by an Alter-type slatted wind screen. Its collection orifice is positioned 1 m above ground level. <br><br> The results from the seven events show that the tipping-bucket gauges noticeably underestimated storm event rainfall totals relative to the weighing-bucket gauge when 1-min rain rates exceeded about 50 mm/h (2 in/h). In addition, we conclude that observable wind induced undercatch by the aboveground tipping bucket gauge begins when the wind speed at a height of 2 m exceeds around 5 m/s. In this paper we show and discuss time series of rain rates, differences in rain rates, and wind speeds for two of the seven events in an attempt to account for the lower storm totals from the two tipping bucket gauges relative to the weighing-bucket gauge. Alter, C. J.: Shielded storage precipitation gages, Mon. Weather Rev., 65, 262–265, 1937. Brock, F. V., Crawford, K. C., Elliot, R. L., Cuperus, G. W., Stadler, S. J., Johnson, H. L., and Eilts, M. D.: The Oklahoma Mesonet: A technical review, J. Atmos. Oceanic Technol., 12, 5–19, 1995. Cleveland, W. S.: Robust locally weighted regression and smoothing scatterplots, J. Am. Stat. Assoc., 74, 829–836, 1979. Duchon, C. E. and Essenberg, G. R.: Comparative rainfall observations from pit and aboveground gauges with and without wind shields, Water Resour. Res., 37(12), 3253–3263, 2001. Duchon, C. E.: Using vibrating-wire technology for precipitation measurements, Chapter 2, in: Precipitation: Advances in Measurement, Estimation and Prediction, edited by: Michaelides, S., Springer, ISBN: 978-3-540-77654-3, 2008. Folland, C. K.: Numerical models of the raingauge exposure problem, field experiments and an improved collector design, Q. J. R. Meteorol. Soc., 114, 1485–1516, 1988. Galarneau, Jr., T. J., Bosart, L. F., and Schumacher, R. S.: Reintensification of Tropical Storm Erin (2007) over Oklahoma, Bull. Amer. Meteor. Soc., 90(3), 306–308, 2009. Nešpor, V. and Sevruk, B.: Estimation of wind-induced error of rainfall gauge measurements using a numerical simulation, J. Atmos. Oceanic Technol., 16, 450–464, 1999.