• Barnes, S. L., 1964: A technique for maximizing details in numerical weather map analysis. J. Appl. Meteor., 3 , 396409.

  • Bar-Sever, Y. E., P. M. Kroger, and J. A. Borjesson, 1998: Estimating horizontal gradients of tropospheric path delay with a single GPS receiver. J. Geophys. Res., 103 , 50195035.

    • Search Google Scholar
    • Export Citation
  • Bevis, M., S. Businger, T. A. Herring, C. Rocken, R. A. Anthes, and R. H. Ware, 1992: GPS meteorology: Remote sensing of atmospheric water vapor using the Global Positioning System. J. Geophys. Res., 97 , 1578715801.

    • Search Google Scholar
    • Export Citation
  • Chang, S., D. Hahn, C. Yang, D. Norquist, and M. Ek, 1999: Validation study of the CAPS model land surface scheme using the 1987 Cabauw/PILPS dataset. J. Appl. Meteor., 38 , 405422.

    • Search Google Scholar
    • Export Citation
  • Cho, H., M. Niewiadomski, and J. Iribarne, 1989: A model of the effect of cumulus clouds on the redistribution and transformation of pollutants. J. Geophys. Res., 94 , 1289512910.

    • Search Google Scholar
    • Export Citation
  • De Pondeca, M., and X. Zou, 2001: Moisture retrievals from simulated zenith delay “observations” and their impact on short-range precipitation forecasts. Tellus, 53A , 192214.

    • Search Google Scholar
    • Export Citation
  • Foster, J., and Coauthors, 2000: El Niño, water vapor, and the Global Positioning System. Geophys. Res. Lett., 27 , 26972700.

  • Fu, Q., and K-N. Liou, 1993: Parameterization of the radiative properties of cirrus clouds. J. Atmos. Sci., 50 , 20082025.

  • Genrich, J. F., and Y. Bock, 2006: Instantaneous geodetic positioning with 10–50 Hz GPS measurements: Noise characteristics and implications for monitoring networks. J. Geophys. Res., 111 .B03403, doi:10.1029/2005JB003617.

    • Search Google Scholar
    • Export Citation
  • Gu, Y., J. Fararra, K-N. Liou, and C. R. Mechoso, 2003: Parameterization of cloud–radiation processes in the UCLA general circulation model. J. Climate, 16 , 33573370.

    • Search Google Scholar
    • Export Citation
  • Gutman, S. I., S. R. Sahm, S. G. Benjamin, B. E. Schwartz, K. L. Holub, J. Q. Stewart, and T. L. Smith, 2004: Rapid retrieval and assimilation of ground based GPS precipitable water observations at the NOAA forecast systems laboratory: Impact on weather forecasts. J. Meteor. Soc. Japan, 82 , 351360.

    • Search Google Scholar
    • Export Citation
  • Haines, B. J., and Y. E. Bar-Sever, 1998: Monitoring the TOPEX microwave radiometer with GPS: Stability of columnar water vapor measurements. Geophys. Res. Lett., 25 , 35643566.

    • Search Google Scholar
    • Export Citation
  • Jibson, R. W., 2005: Landslide hazards at La Conchita, California. USGS Open-File Rep. 2005-1067, U.S. Department of the Interior, 12 pp.

  • Kim, J., 2005: A projection of the effects of the climate change induced by increased CO2 on extreme hydrologic events in the western U.S. Climatic Change, 68 , 153168.

    • Search Google Scholar
    • Export Citation
  • Kim, J., and M. Ek, 1995: A simulation of the surface energy budget and soil water content over the Hydrologic Atmospheric Pilot Experiments-Modelisation du Bilan Hydrique forest site. J. Geophys. Res., 100 , 2084520854.

    • Search Google Scholar
    • Export Citation
  • Kuo, Y., 2006: Assimilation of ground-based GPS data for short-range precipitation forecast. Preprints, Fourth Korea–US Joint Workshop on Mesoscale Observations, Data Assimilation, and Modeling for Severe Weather, Seoul, Korea, KOSEF and NSF/OISE, 38–41.

  • Kuo, Y., Y. Guo, and E. Westwater, 1993: Assimilation of precipitable water measurements into a mesoscale model. Mon. Wea. Rev., 121 , 12151238.

    • Search Google Scholar
    • Export Citation
  • Mahrt, L., and H. Pan, 1984: A two-layer model of soil hydrology. Bound.-Layer Meteor., 29 , 120.

  • Marcus, S. L., J. Kim, T. M. Chin, J. O. Dickey, D. Danielson, C. Jacobson, and J. Laber, 2004: A regional NWP system for southern California: Applications of GPS-derived PWV retrievals. Eos, Trans. Amer. Geophys. Union, 85 .Fall Meeting Suppl. Abstract A53A-0853.

    • Search Google Scholar
    • Export Citation
  • Marcus, S. L., J. Kim, T. M. Chin, D. Danielson, and J. Laber, 2005: Impact of GPS-derived PWV data on regional QPF in southern California. Eos, Trans. Amer. Geophys. Union, 86 .Fall Meeting Suppl. Abstract G13A-04.

    • Search Google Scholar
    • Export Citation
  • Nakamura, H., K. Koizumi, and N. Mannoji, 2004: Data assimilation of GPS precipitable water vapor into the JMA mesoscale numerical weather prediction model and its impact on rainfall forecasts. J. Meteor. Soc. Japan, 82 , 441452.

    • Search Google Scholar
    • Export Citation
  • Neiman, P. J., P. O. G. Persson, F. M. Ralph, D. P. Jorgensen, A. B. White, and D. E. Kingsmill, 2004: Modification of fronts and precipitation caused by coastal blocking during an intense landfalling winter storm in southern California: Observations during CALJET. Mon. Wea. Rev., 132 , 242273.

    • Search Google Scholar
    • Export Citation
  • Nezlin, N. P., and E. D. Stein, 2005: Spatial and temporal patterns of remotely-sensed and field-measured rainfall in southern California. Remote Sens. Environ., 96 , 228245.

    • Search Google Scholar
    • Export Citation
  • Pan, H., and L. Mahrt, 1987: Interaction between soil hydrology and boundary layer development. Bound.-Layer Meteor., 38 , 185202.

  • Pan, H., and W. Wu, 1995: Implementing a mass flux convection parameterization package for the NCEP medium-range forecast model. NMC Office Note, 40 pp. [Available from NCEP/EMC, 5200 Auth Road, Camp Springs, MD 20764.].

  • Roe, G. H., 2005: Orographic precipitation. Annu. Rev. Earth Planet. Sci., 33 , 645671.

  • Soong, S., and J. Kim, 1996: Simulation of a heavy precipitation event in California. Climatic Change, 32 , 5577.

  • Takacs, L., 1985: A two-step scheme for the advection equation with minimized dissipation and dispersion error. Mon. Wea. Rev., 113 , 10501065.

    • Search Google Scholar
    • Export Citation
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Influence of GPS Precipitable Water Vapor Retrievals on Quantitative Precipitation Forecasting in Southern California

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  • 1 Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California
  • | 2 University of California at Los Angeles, Los Angeles, California
  • | 3 Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California
  • | 4 National Weather Service Forecast Office, Oxnard, California
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Abstract

The effects of precipitable water vapor (PWV) retrievals from the Southern California Integrated GPS Network (SCIGN) on quantitative precipitation forecast (QPF) skill are examined over two flood-prone regions of Southern California: Santa Barbara (SB) and Ventura County (VC). Two sets of QPFs are made, one using the initial water vapor field from the NCEP 40-km Eta initial analysis, and another in which the initial Eta water vapor field is modified by incorporating the PWV data from the SCIGN receivers. Lateral boundary data for the QPFs, as well as the hydrostatic component of the GPS zenith delay data, are estimated from the Eta analysis. Case studies of a winter storm on 2 February during the 1997/98 El Niño, and storms leading up to the La Conchita, California, landslide on 10 January 2005, show notably improved QPFs for the first 3–6 h with the addition of GPS PWV data. For a total of 47 winter storm forecasts between February 1998 and January 2005 the average absolute QPF improvement is small; however, QPF improvements exceed 5 mm in several underpredicted rainfall events, with GPS data also improving most cases with overpredicted rainfall. The GPS improvements are most significant (above or near the 2σ level) when the low-level winds off the coast of Southern California are from the southern (SW to SE) quadrant. To extend the useful forecast skill enhancement beyond six hours, however, additional sources of water vapor data over broader areas of the adjacent Pacific Ocean are needed.

Corresponding author address: Steven Marcus, Jet Propulsion Laboratory, Mail Stop 238-600, Pasadena, CA 91109. Email: Steven.Marcus@jpl.nasa.gov

Abstract

The effects of precipitable water vapor (PWV) retrievals from the Southern California Integrated GPS Network (SCIGN) on quantitative precipitation forecast (QPF) skill are examined over two flood-prone regions of Southern California: Santa Barbara (SB) and Ventura County (VC). Two sets of QPFs are made, one using the initial water vapor field from the NCEP 40-km Eta initial analysis, and another in which the initial Eta water vapor field is modified by incorporating the PWV data from the SCIGN receivers. Lateral boundary data for the QPFs, as well as the hydrostatic component of the GPS zenith delay data, are estimated from the Eta analysis. Case studies of a winter storm on 2 February during the 1997/98 El Niño, and storms leading up to the La Conchita, California, landslide on 10 January 2005, show notably improved QPFs for the first 3–6 h with the addition of GPS PWV data. For a total of 47 winter storm forecasts between February 1998 and January 2005 the average absolute QPF improvement is small; however, QPF improvements exceed 5 mm in several underpredicted rainfall events, with GPS data also improving most cases with overpredicted rainfall. The GPS improvements are most significant (above or near the 2σ level) when the low-level winds off the coast of Southern California are from the southern (SW to SE) quadrant. To extend the useful forecast skill enhancement beyond six hours, however, additional sources of water vapor data over broader areas of the adjacent Pacific Ocean are needed.

Corresponding author address: Steven Marcus, Jet Propulsion Laboratory, Mail Stop 238-600, Pasadena, CA 91109. Email: Steven.Marcus@jpl.nasa.gov

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