ANGEO Annales Geophysicae ANGEO Ann. Geophys. 1432-0576 Copernicus Publications Göttingen, Germany 10.5194/angeo-27-2739-2009 Impact of high-resolution data assimilation of GPS zenith delay on Mediterranean heavy rainfall forecasting Boniface K. 1 Ducrocq V. 2 Jaubert G. 2 Yan X. 2 Brousseau P. 2 Masson F. 3 Champollion C. 1 Chéry J. 1 Doerflinger E. 1 Géosciences Montpellier, UMR 5243 CNRS-UM2, CC. 60, Place E. Bataillon, 34095 Montpellier Cedex 5, France GAME-CNRM, CNRS-Météo-France, 42 Avenue Coriolis, 31057 Toulouse Cedex 1, France UMR 7516-IPGS-CNRS-EOST, 5 rue René Descartes, 67084 Strasbourg Cedex, France 09 07 2009 27 7 2739 2753 Copyright: © 2009 K. Boniface et al. 2009 This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/3.0/ This article is available from https://angeo.copernicus.org/articles/27/2739/2009/angeo-27-2739-2009.html The full text article is available as a PDF file from https://angeo.copernicus.org/articles/27/2739/2009/angeo-27-2739-2009.pdf

Impact of GPS (Global Positioning System) data assimilation is assessed here using a high-resolution numerical weather prediction system at 2.5 km horizontal resolution. The Zenithal Tropospheric Delay (ZTD) GPS data from mesoscale networks are assimilated with the 3DVAR AROME data assimilation scheme. Data from more than 280 stations over the model domain have been assimilated during 15-day long assimilation cycles prior each of the two studied events. The results of these assimilation cycles show that the assimilation of GPS ZTD with the AROME system performs well in producing analyses closer to the ZTD observations in average. <br><br> Then the impacts of assimilating GPS data on the precipitation forecast have been evaluated. For the first case, only the AROME runs starting a few hours prior the triggering of the convective system are able to simulate the convective precipitation. The assimilation of GPS ZTD observations improves the simulation of the spatial extent of the precipitation, but slightly underestimates the heaviest precipitation in that case compared with the experiment without GPS. The accuracy of the precipitation forecast for the second case is much better. The analyses from the control assimilation cycle provide already a good description of the atmosphere state that cannot be further improved by the assimilation of GPS observations. Only for the latest day (22 November 2007), significant differences have been found between the two parallel cycles. In that case, the assimilation of GPS ZTD allows to improve the first 6 to 12 h of the precipitation forecast.

 References Anthes, R.: Regional Models of the Atmosphere in Middle Latitudes, Mon. Weather Rev., 111, 1306–1335, 1983. Benard, P.: On the use of a wider class of linear systems for the design of constant-coefficients semi-implicit time schemes in NWP, Mon. Weather Rev., 132, 1319–1324, 2004. Berre, L., Stefanescu, S., and Pereira, M.: The representation of the analysis effect in three error simulation techniques, Tellus Series A-Dynamic Meteorology and Oceanography, 58, 196–209, 2006. Bevis, M., Businger, S., Herring, T., C., R., Anthes, R., and Ware, R.: GPS Meteorology : Remote Sensing of Atmospheric Water Vapor Using the Global Positioning System, J. Geophys. Res., 97, 15787–15801, 1992. Bock, O., Keil, C., Richard, E., Flamant, C., and Bouin, M.: Validation of precipitable water from ECMWF model analyses with GPS and radiosonde data during the MAP SOP, Q. J. Roy. Meteorol. Soc., 131, 3013–3036, 2005. Bouttier, F.: Arome, avenir de la prévision régionale, La Météorologie, 58, 12–20, 2007. Brenot, H., Ducrocq, V., Walpersdorf, A., Champollion, C., and Caumont, O.: GPS Zenith Delay Sensitivity Evaluated from High-Resolution NWP simulations of the $8-9^th$ September 2002 Flash-Flood over Southeastern France, J. Geophys. Res., 111, D15105, \doi10.1029/2004JD005726, 2006. Bubnova, R., Hello, G. P. B., and Geleyn, J.-F.: Integration of the fully elastic equations cast in the hydrostatic pressure terrain-following coordinate in the framework of the Arpge/Aladin NWP system., Mon. Weather Rev., 123, 515–535, 1995. Caniaux, G., Redelsperger, J., and Lafore, J.: A Numerical Study of the Stratiform Region of a Fast-Moving Squall Line .1. General Description and Water and Heat Budgets, J. Atmos. Sci., 51, 2046–2074, 1994. Champollion, C., Masson, F., Van~Baelen, J., Walpersdorf, A., Chery, J., and Doerflinger, E.: GPS monitoring of the tropospheric water vapor distribution and variation during the 9 September 2002 torrential precipitation episode in the Cevennes (Southern France), J. Geophys. Res., 109, D24102, https://doi.org/10.1029/2004JD004897, 2004. Courtier, P., Thepaut, J., and Hollingsworth, A.: A Strategy for Operational Implementation of 4D-VAR, Using an Incremental Approach, Q. J. Roy. Meteorol. Soc., 120, 1367–1387, 1994. Cuxart, J., Bougeault, P., and Redelsperger, J.: A turbulence scheme allowing for mesoscale and large-eddy simulations, Q. J. Roy. Meteorol. Soc., 126, 1–30, 2000. Delrieu, G., Ducrocq, V., Gaume, E., Nicol, J., Payrastre, O., Yates, E., Kirstetter, P., Andrieu, H., Ayral, P., Bouvier, C., Creutin, J., Livet, M., Anquetin, S., Lang, M., Neppel, L., Obled, C., Parent-du Chatelet, J., Saulnier, G., Walpersdorf, A., and Wobrock, W.: The catastrophic flash-flood event of 8-9 September 2002 in the Gard region, France: A first case study for the Cevennes-Vivarais Mediterranean Hydrometeorological Observatory, J. Hydrometeorol., 6, 34–52, 2005. Ducrocq, V., Ricard, D., Lafore, J., and Orain, F.: Storm-scale numerical rainfall prediction for five precipitating events over France: On the importance of the initial humidity field, Weather and Forecasting, 17, 1236–1256, 2002. Emardson, T., Elgered, G., and Johansson, J.: Three months of continuous monitoring of atmospheric water vapor with a network of Global Positioning System receivers, J. Geophys. Res. Atmos., 103, 1807–1820, 1998. Fischer, C., Montmerle, T., Berre, L., Auger, L., and Stefanescu, S.: An overview of the variational assimilation in the ALADIN/France numerical weather-prediction system, Q. J. Roy. Meteorol. Soc., 131, 3477–3492, \doi10.1256/qj.05.115, 2005. Fujita, M., Kimura, F., Yoneyama, K., and Yoshizaki, M.: Verification of precipitable water vapor estimated from shipborne GPS measurements, Geophys. Res. Lett., 35, L13803, https://doi.org/10.1029/2008GL033764, 2008. Gutman, S., Sahm, S., Benjamin, S., Schwartz, B., Holub, K., Stewart, J., and Smith, T.: Rapid retrieval and assimilation of ground based GPS precipitable water observations at the NOAA forecast systems laboratory: Impact on weather forecasts, J. Meteorol. Soc. Jpn., 82, 351–360, 2004. Kelecy, T., Born, G., Parke, M., and Rocken, C.: Precise Mean Sea-Level Measurements Using The Global Positioning System, J. Geophys. Res.-Oceans, 99, 7951–7959, 1994. King, R. and Bock, Y.: Documentation for the GAMIT GPS analysis software, Release 10.32. Mass. Inst. of Technol., Cambridge., 2007. Klein~Baltink, H., Van Der~Marel, H., and Van Der~Hoeven, A. G A.: Integrated atmospheric water vapor estimates from a regional GPS network, J. Geophys. Res., 107, 4025, \doi10.1029/2000JD000094, 2002. Kopken, C.: Validation of integrated water vapor from numerical models using ground-based GPS, SSM/I, and water vapor radiometer measurements, J. Appl. Meteor., 40, 1105–1117, 2001. Kuo, Y., Zou, X., and Guo, Y.: Variational assimilation of precipitable water using a nonhydrostatic mesoscale adjoint model .1. Moisture retrieval and sensitivity experiments, Mon. Weather Rev., 124, 122–147, 1996. Kuo, Y., Zou, X., and Huang, W.: The impact of Global Positioning System data on the prediction of an extratropical cyclone: an observing system simulation experiment, Dynam. Atmos. Oceans, 27, 439–470, 1998. Lafore, J., Stein, J., Asencio, N., Bougeault, P., Ducrocq, V., Duron, J., Fischer, C., Hereil, P., Mascart, P., Masson, V., Pinty, J., Redelsperger, J., Richard, E., and de~Arellano, J.: The Meso-NH atmospheric simulation system. Part I: adiabatic formulation and control simulations, Ann. Geophys.-Atmospheres Hydrospheres and Space Sciences, 16, 90–109, 1998. Masson, V.: A physically-based scheme for the urban energy budget in atmospheric models, Bound.-Lay. Meteorol., 94, 357–397, 2000. Mlawer, E., Clough, S., Brown, P., Stephen, T., Landry, J., Goldman, A., and Murcray, F.: Observed atmospheric collision-induced absorption in near-infrared oxygen bands, J. Geophys. Res.-Atmos., 103, 3859–3863, 1998. Montmerle, T., Rabier, F., and Fischer, C.: Relative impact of polar-orbiting and geostationary satellite radiances in the Aladin/France numerical weather prediction system, Q. J. Roy. Meteorol. Soc., 133, 655–671, 2007. Niell, A.: Global mapping functions for the atmosphere delay at radio wavelengths, J. Geophys. Res., 101, 3227–3246, 1996. Noilhan, J. and Mahfouf, J.: The ISBA land surface parameterisation scheme, Global and Planetary Change, 13, 145–159, 1996. Nuissier, O., Ducrocq, V., Ricard, D., Lebeaupin, C., and Anquetin, S.: A numerical study of three catastrophic precipitating events over southern France. I: Numerical framework and synoptic ingredients, Q. J. Roy. Meteorol. Soc., 134, 111–130, 2008. Poli, P., Moll, P., Rabier, F., Desroziers, G., Chapnik, B., Berre, L., Healy, S B., Andersson, E., and El~Guelai, F.-Z.: Forecast impact studies of zenith total delay data from European near real-time GPS stations in Météo France 4DVAR, J. Geophys. Res., 112, D06114, \doi10.1029/2006JD007430, 2007. Rivrain, J.: Les épisodes orageux à précipitations extrêmes dans les régions Méditerrannéennes du sud de la France (Storm-floods in the Mediterranean region of southern of France), Phénomènes remarquables, vol 4, météo-france, scem edn., 1998. Rocken, C., Vanhove, T., Johnson, J., Solheim, F., Ware, R., Bevis, M., Chiswell, S., and Businger, S.: GPS/STORM - GPS Sensing of Atmospheric Water-Vapor for Meteorology, J. Atmos. Oceanic Technology, 12, 468–478, 1995. Rocken, C., Johnson, J., Van~Hove, T., and Iwabuchi, T.: Atmospheric water vapor and geoid measurements in the open ocean with GPS, Geophys. Res. Lett., 32, L12813, https://doi.org/10.1029/2005GL022573, 2005. Saastamoinen, J.: Introduction to practical computation of astronomical refraction, Bull. Geod., 106, 389–397, 1972. Smith, E. and Weintraub, S.: The constants in the equation for atmospheric index at radio frequencies, Proc. IRE, 41, 1035–1037, 1953. Tregoning, P., Boers, R., O'Brien, D., and Hendy, M.: Accuracy of absolute precipitable water vapor estimates from GPS observations, J. Geophys. Res.-Atmos., 103, 28701–28710, 1998. Vedel, H. and Huang, X.: Impact of ground based GPS data on numerical weather prediction, J. Meteorol. Soc. Jpn., 82, 459–472, International Workshop on GPS Meteorology, Tsukuba, JAPAN, 14–17 January 2003, 2004. Vedel, H., Huang, X., Haase, J., Ge, M., and Calais, E.: Impact of GPS Zenith Tropospheric Delay data on precipitation forecasts in Mediterranean France and Spain, Geophys. Res. Lett., 31, L02102, https://doi.org/10.1029/2003GL017715, 2004. Yan, X., Ducrocq, V., Poli, P., Jaubert, G., and Walpersdorf, A.: Mesoscale GPS Zenith Delay assimilation during a Mediterranean heavy precipitation event, Adv. Geosci., 17, 71–77, 2008. Yan, X., Ducrocq, V., Jaubert, G., Brousseau, P., Poli, P., Champollion, C., and Boniface, K.: Benefit of GPS Zenith Delay Assimilation on high-resolution Quantitative Precipitation Forecast of the COPS cases IOP9, Q. J. Roy. Meteorol. Soc., accepted, 2009. Zhang, C., Kuo, Y., Dai, L., Chu, Y., Braun, J., Zhang, J., Li, Q., and Chen, M.: The Design and Application of Network of Ground-Based GPS Water Vapor Monitoring stations to Improve Precipitation Precipitation Prediction in the Greater Beijing Metropolitan area, The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, 37, 2008. Zou, X., Kuo, Y., and Guo, Y.: Assimilation of Atmospheric Radio Refractivity using a Nonhydrostatic Adjoint Model, Mon. Weather Rev., 123, 2229–2249, 1995.