Slide 1

Rainfall Measurements at NASA Wallops Island Dover NEXRAD = 110 km Wakefield NEXRAD = 165 km Sterling NEXRAD = 215 km Ali Tokay (JCET/UMBC, NASA/GSFC) and John Gerlach (NASA/WFF), Slide 2 Wallops Island Precipitation Variability Slide 3 Wallops Island Precipitation Days Slide 4 Wallops Island Snowfall Slide 5 Wallops Island Precipitation Type Frontal (Cold, warm, stationary) Solar heating Coastal low Tropical cyclones Winter storms (dry and wet snow) Slide 6 Wallops Island Precipitation Type Frontal (cold, warm, stationary) Solar heating Coastal low Tropical cyclones Winter storms (dry and wet snow) Slide 7 Wallops Island Precipitation Type Frontal (cold, warm, stationary) Solar heating Coastal low Tropical cyclones Winter storms (dry and wet snow) Slide 8 Wallops Island - Instruments (NASA) Radars - S-band Polarimetric radar (NPOL) - S-band Doppler radar (SPANDAR) - C-band Doppler radar (TOGA) - UHF reflector - Dual frequency Microwave Link (R. Rincon) Precipitation Gauges - Met 1 tipping bucket gauges (14 unit) - Qualimetrics tipping bucket gauges (11 unit) - Geonor weighing bucket gauge - Optical rain gauges (5 unit, R. Rincon) Disdrometers - Joss-Waldvogel disdrometers (9 unit, 2 for R. Rincon) - Optical (Parsivel) disdrometers (2 unit) - 2-D video disdrometer (1 unit) - Video disdrometer (L. Bliven) Slide 9 Wallops Island - Instruments (Loan, past & present) Radars - X-band polarimetric radar (NOAA-ETL, PI: S. Matrosov and B. Martner) - X-band polarimetric radar (Greek Met. Service, PI: E. Anagnostou) - S-band profiler (NOAA-AL, PI: K. Gage) - 24.5 GHz profiler (Metek) Precipitation Gauges - Hydrological services tipping bucket gauges (2 unit) - Geonor weighing bucket gauge - Drop counting gauge (RL, PI: C. Wilson) Disdrometers - Pludix (Nubila, PI: F. Prodi) - POSS (2 unit, Canadian Met. Service, PI: P. Joe and B. Sheppard) Slide 10 Performance of Tipping Bucket Gauges Slide 11 X1>X2 Performance of Impact-type, Laser-Optical, and Radar Disdrometers Slide 12 Performance of Impact-type, 2-D Video, and Laser-Optical Disdrometers Slide 13 Wallops Island Data Acquisition Network: Phase I Slide 14 Small-Scale Variability of Rainfall and Reflectivity Slide 15 Wallops Island Data Acquisition Network: Phase II Slide 16 Wallops Island - Instruments (NOAA) Radars - S-band Doppler radar at Dover, Delaware - S-band Doppler radar at Wakefield, Virginia Precipitation Gauges - ASOS site - CRN site at Oyster, Virginia US NLDN sensor site Upper air sounding site Slide 17 Doppler Radar Rain Gauge Network Slide 18 Monthly and Daily Rainfall Statistics Standard deviation of daily rain total difference (STRTD) SDRTD = [Var(G1)+Var(G2)-2Cov(G1,G2)] 1/2 Monthly rainfall bias Mean daily rain total difference and its standard deviation Pearson correlation coefficient of daily rainfall where G1>G2 where N - number of rainy days with rainfall > 1.2 mm Slide 19 Oyster, Virginia Climate Reference Network (CRN) site Slide 20 Wakefield, Virginia Automated Surface Observing System (ASOS) site Slide 21 Gauge and 88-D Rainfall Totals in Tropical Storm Guston 88-D rainfall products - 1.0,1.5, 2.0 km grid spacing, 1.0, 1.5, 2.0 CAPPI Gauge sites - NASA, ASOS, AWOS, co-op, weather-bug, state Slide 22 Proposed Wallops Island Triple Radar Rain Gauge Network Slide 23 Publications Journal papers: Tokay, A., R. Chamberlain, and M. Schoenhuber, 2000: Laboratory and field measurements of raindrop oscillations. Phys. Chem. Earth (B), 25, 867-870. Matrosov, S. Y., K. A. Clark, B. E. Martner, and A. Tokay, 2002: X-band polarimetric radar measurements of rainfall. J. Appl. Meteor., 41, 941-952. Rincon, R., and R. Lang, 2002: Microwave link dual-wavelength measurements of path-average attenuation for the estimation of drop size distributions and rainfall. IEEE Trans. Geoscience and Remote Sensing, 40, 760-769. Gage, K.S., W.L. Clark, C.R. Williams and A. Tokay, 2004: Determining Reflectivity Measurement Error from Serial Measurements Using Paired Disdrometers and Profilers. Geo. Res. Lett., 31, doi:10.1029/020591. Tokay, A., P. G. Bashor, and K. R. Wolff, 2005: Error Characteristics of Rainfall measurements by collocated Joss-Waldvogel disdrometers. J. Atmos. Oceanic. Technol., 22, 513-527. Larsen, M. L., A. B. Kostinski, and A. Tokay, 2005: Observations and analysis of steady rain. J. Atmos. Sci., (accepted for publication). Tokay, A.,and P. G. Bashor, 2005: An experimental study of small-scale variability of rainfall. J. Appl. Meteor. (submitted July 2005). Goldhirsh, J., 1983: On modeled slant path attenuation distributions, IEEE Trans. Antennas and Propagation, 31, 918-921. Slide 24 Conference papers and presentations Tokay, A., K. Chamberlain, P. Bashor, R. Rincon, and D. Wolff, 2000: Measurements of Drop size distribution and drop shape at the NASA Wallops Flight Facility, TRMM science meeting, College Park, Maryland Tokay, A., K. Chamberlain, P. Bashor, R. Rincon, and D. Wolff, 2001: Drop size distribution measurements at the NASA Wallops Flight Facility, GPM planning meeting, College Park, Maryland Tokay, A., K. Chamberlain, P. Bashor, R. Rincon, and D. Wolff, 2001: Precipitation measurements at the NASA Wallops Flight Facility. Abstracts, 7 th International Conference on Precipitation, Rockport, Maine, 2-2 Tokay, A., K. R. Wolff, P. Bashor, and R. Rincon, 2002: An overview of the precipitation measurements at the NASA Wallops Island. Abstracts, 2 nd European Radar Meteorology Conference, Delft, The Netherlands. Tokay, A., R. Wolff, P. Bashor, and O. Dursun, 2003: On the measurement errors of the Joss-Waldvogel disdrometer. Preprints, 31 th International Conference on Radar Meteorology. Seattle, WA, American Meteorological Society, 437-440. Tokay, D. B. Wolff, P. Bashor, and R. Rincon, 2003: Wallops Island: Proposed ground validation site for the NASA precipitation program, European Global Precipitation Mission (EGPM) meeting in ESA/ESTEC, The Netherlands. Tokay, A, D. B. Wolff, D. Marks, J. Gerlach, J. J. Wang, P. Bashor, and R. Wolff 2003: Greater Wallops Island: A proposed mid-latitudinal ground validation site for NASA precipitation program. GPM Ground Validation (GV) meeting in Abingdon, UK.