TITLE

Short-Range Forecast Impact from Assimilation of GPS-IPW Observations into the Rapid Update Cycle

AUTHOR(S)
Smith, Tracy Lorraine; Benjamin, Stanley G.; Gutman, Seth I.; Sahm, Susan
PUB. DATE
August 2007
SOURCE
Monthly Weather Review;Aug2007, Vol. 135 Issue 8, p2914
SOURCE TYPE
Academic Journal
DOC. TYPE
Article
ABSTRACT
Integrated precipitable water (IPW) estimates derived from time delays in the arrival of global positioning system (GPS) satellite signals are a relatively recent, high-frequency source of atmospheric moisture information available for real-time data assimilation. Different experimental versions of the Rapid Update Cycle (RUC) have assimilated these observations to assess GPS-IPW impact on moisture forecasts. In these tests, GPS-IPW data have proven to be a useful real-time source of moisture information, leading to more accurate short-range moisture forecasts when added to other observations. A multiyear experiment with parallel (one with GPS-IPW processed 24 h after the fact, one without) 3-h cycles using the original 60-km RUC was run from 1999 to 2004 with verification of each cycle against rawinsonde observations. This experiment showed a steady increase in the positive impact in short-range relative humidity (RH) forecasts due to the GPS-IPW data as the number of observing sites increased from 18 to almost 300 (as of 2004) across the United States and Canada. Positive impact from GPS-IPW on 850–700-hPa RH forecasts was also evident in 6- and 12-h forecasts. The impact of GPS-IPW data was also examined on forecasts from the more recent 20-km RUC, including a 1-h assimilation cycle and improved assimilation and physical parameterizations, now using real-time GPS-IPW retrievals available 30 min after valid time. In a 3-month comparison during the March–May 2004 period, 20-km RUC cycles with and without assimilation of GPS-IPW were compared with IPW for 3-, 6-, 9-, and 12-h forecasts. Using this measure, assimilation of GPS-IPW data led to the strongest improvements in the 3- and 6-h forecasts and smaller but still evident improvements in 9- and 12-h forecasts. In a severe convective weather case, inclusion of GPS-IPW data improved forecasts of convective available potential energy, an important predictor of severe storm potential, and relative humidity. Positive impact from GPS-IPW assimilation was found to vary over season, geographical location, and time of day, apparently related to variations in vertical mixing. For example, GPS-IPW has a stronger effect on improving RH forecasts at 850 hPa at nighttime (than daytime) and in cooler seasons (than warmer seasons) when surface moisture observations are less representative of conditions aloft. As a result of these studies, assimilation of GPS-IPW was added to the operational RUC run at NOAA/NCEP in June 2005 and to the operational North American Mesoscale model (also at NCEP) in June 2006 to improve their accuracy for short-range moisture forecasts.
ACCESSION #
26491069

 

Related Articles

  • Trends and variability in column-integrated atmospheric water vapor. Trenberth, Kevin; Fasullo, John; Smith, Lesley // Climate Dynamics;Jun2005, Vol. 24 Issue 7/8, p741 

    An analysis and evaluation has been performed of global datasets on column-integrated water vapor (precipitable water). For years before 1996, the Ross and Elliott radiosonde dataset is used for validation of European Centre for Medium-range Weather Forecasts (ECMWF) reanalyses ERA-40. Only the...

  • Atmosphere-Ocean Heat Fluxes and Stresses in General Circulation Models. Lambert, S. J.; Boer, G. J. // Atmosphere -- Ocean (Canadian Meteorological & Oceanographic Soc;Dec1989, Vol. 27 Issue 4, p692 

    The coupling of atmospheric general circulation models (AGCMs) to oceanic general circulation models (OGCMs) requires that each behaves appropriately in the uncoupled mode. The lower boundary conditions for uncoupled AGCMs are particularly simple over the oceans and consist of the specified...

  • Influence of GPS Precipitable Water Vapor Retrievals on Quantitative Precipitation Forecasting in Southern California. Marcus, Steven; Jinwon Kim; Toshio Chin; Danielson, David; Laber, Jayme // Journal of Applied Meteorology & Climatology;Nov2007, Vol. 46 Issue 11, p1828 

    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...

  • Improving Global Analysis and Short-Range Forecast Using Rainfall and Moisture Observations Derived from TRMM and SSM/I Passive Microwave Sensors. Hou, Arthur Y.; Zhang, Sara Q.; da Silva, Arlindo M.; Olson, William S.; Kummerow, Christian D.; Simpson, Joanne // Bulletin of the American Meteorological Society;Apr2001, Vol. 82 Issue 4, p659 

    Describes the benefits of using rainfall and total precipitable water (TPW) information derived from instruments in global data assimilation with observations from the Tropical Rainfall Measuring Mission Microwave Imager and two Special Sensor Microwave/Imager instruments. Importance of...

  • Impacts of Satellite-Observed Winds and Total Precipitable Water on WRF Short-Range Forecasts over the Indian Region during the 2006 Summer Monsoon. Rakesh, V.; Singh, Randhir; Pal, P. K.; Joshi, P. C. // Weather & Forecasting;Dec2009, Vol. 24 Issue 6, p1706 

    Assimilation experiments have been performed with the Weather Research and Forecasting (WRF) model’s three-dimensional variational data assimilation (3DVAR) scheme to assess the impacts of NASA’s Quick Scatterometer (QuikSCAT) near-surface winds, and Special Sensor Microwave Imager...

  • A refined statistical cloud closure using double-Gaussian probability density functions. Naumann, A. K.; Seifert, A.; Mellado, J. P. // Geoscientific Model Development;2013, Vol. 6 Issue 5, p1641 

    We introduce a probability density function (PDF)-based scheme to parameterize cloud fraction, average liquid water and liquid water flux in large-scale models, that is developed from and tested against large-eddy simulations and observational data. Because the tails of the PDFs are crucial for...

  • Influence of Initial Conditions on Summer Precipitation Simulations over the United States and Mexico. Mo, Kingtse C.; Schemm, J. E.; Kim, H.; Higgins, W. R. // Journal of Climate;Aug2006, Vol. 19 Issue 15, p3640 

    The impact of initial conditions on summer precipitation over North America for July–September was examined by comparing long-term simulations of the Atmospheric Model Intercomparison Project (AMIP) runs with the ensemble simulations (SIMUs) initialized at the end of June each year. Both...

  • Water budget in the Baltic Sea drainage basin: Evaluation of simulated fluxes in a regional climate model. Lind, Peter; Kjellström, Erik // Boreal Environment Research;2009, Vol. 14 Issue 1, p56 

    We investigated the Rossby Centre regional climate model, RCA3, and its ability to reproduce the water budget of the Baltic Sea drainage basin during the period from 1979 to 2002. The model was forced on its lateral boundaries with European Centre for Medium-Range Weather Forecasts Re-Analysis...

  • Regional Surges of Monsoonal Moisture into the Southwestern United States. Favors, James E.; Abatzoglou, John T. // Monthly Weather Review;Jan2013, Vol. 141 Issue 1, p182 

    Episodic surges of moisture into the southwestern United States are an important attribute of the North American monsoon. Building upon prior studies that identified mesoscale gulf surges using station-based diagnostics, regional surges in monsoonal moisture are identified using precipitable...

Share

Read the Article

Courtesy of THE LIBRARY OF VIRGINIA

Sorry, but this item is not currently available from your library.

Try another library?
Sign out of this library

Other Topics