Impact of GPS-Based Water Vapor Fields on Mesoscale Model Forecasts
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Impact of GPS-Based Water Vapor Fields on Mesoscale Model Forecasts (5th Symposium on Integrated Observing Systems, Albuquerque, NM) Jonathan L. Case and John Manobianco NASA Kennedy Space Center/Applied Meteorology Unit/ENSCO, Inc. Yuanfu Xie NOAA/FSL Randolph Ware*

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Impact of GPS-Based Water Vapor Fields on Mesoscale Model Forecasts

(5th Symposium on Integrated Observing Systems, Albuquerque, NM)

Jonathan L. Case and John Manobianco

NASA Kennedy Space Center/Applied Meteorology Unit/ENSCO, Inc.

Yuanfu Xie

NOAA/FSL

Randolph Ware*

UCAR and Radiometrics Corporation

Teresa Van Hove

UCAR


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Presentation outline Forecasts

  • 3D water vapor analysis with GPS

    • GPS slant delays, simulated network

    • 3DVAR assumptions, results

    • Microwave profiler example

  • Experiment design

    • Simulated slant GPS network

    • ARPS/ADAS assimilation

  • Mesonet demonstration

  • Summary


3d water vapor analysis with gps l.jpg
3D water vapor analysis with GPS Forecasts

  • GPS signals experience atmospheric delay

    • Dry atmospheric delay (temperature and pressure)

    • Wet atmospheric delay (water vapor)

  • Slant path measurements

    • Delays for ~8 satellites in view

    • Provides strong horizontal constraint

  • Humidity soundings

    • Needed for unique solution

    • Can be provided by microwave profilers


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GPS slant delays Forecasts

Provide strong constraints on atmospheric temperature and humidity

Low angle measurements simultaneously constrain many model cells


Simulated slant gps network l.jpg
Simulated slant GPS Forecastsnetwork

  • resolution

    • 40 km horizontal

    • 500 m vertical

  • domain

    • Rockies and high plains

    • surface to 8 km


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3DVAR assumptions Forecasts

40-km GPS grid (~1300 sites)

slant delays down to 1 degree elevation with 7% error

360-km microwave profiler grid (16 sites) with 8% error

surface humidity measurements at GPS sites with 5% error


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Humidity fields at 750 m height. Size and location of the major convective features are similar. Humidity soundings are compared at dry (+) and moist (*) locations [MacDonald et al., Mon. Wea. Rev. (in press) 2001].


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Comparison of dry (left) and moist (right) major convective features are similar. Humidity soundings are compared at dry (+) and moist (*) locations [MacDonald et al., Mon. Wea. Rev. (in press) 2001].ground-truth and 3DVAR humidity soundings [MacDonald et al., Mon. Wea. Rev. (in press) 2001].


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Example microwave profiler sounding major convective features are similar. Humidity soundings are compared at dry (+) and moist (*) locations [MacDonald et al., Mon. Wea. Rev. (in press) 2001].

Microwave profiler observations near Lamont OK by DOE of a dry line passage (around noon on 16 July)


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Experiment design major convective features are similar. Humidity soundings are compared at dry (+) and moist (*) locations [MacDonald et al., Mon. Wea. Rev. (in press) 2001].

  • Purpose

    • Assimilate GPS slant delay data into mesoscale model

    • Evaluate impact on forecast

  • Part I

    • Analyze high resolution humidity field using 3DVAR and simulated GPS slant and tropospheric profile data

    • Evaluate impact of these data on forecasts using the Advanced Regional Prediction System (ARPS)

    • Initialize model using ARPS Data Analysis System (ADAS)

  • Part II

    • Repeat experiment using real GPS and tropospheric profile data

    • Evaluate impact of real GPS slant data on forecast


Arps adas assimilation l.jpg

Simulated network major convective features are similar. Humidity soundings are compared at dry (+) and moist (*) locations [MacDonald et al., Mon. Wea. Rev. (in press) 2001].

Real network

ARPS/ADASassimilation

  • resolution

    • 10 km horizontal

    • 412.5 m vertical (average)

    • Stretched vertical coordinate

  • domain

    • Rockies and plains

    • surface to 16.5 km


Slant gps test bed l.jpg
Slant GPS major convective features are similar. Humidity soundings are compared at dry (+) and moist (*) locations [MacDonald et al., Mon. Wea. Rev. (in press) 2001].test bed

slant GPS (22)

wind radars (7)

microwaveprofiler (1)

water vapor radiometers (5)


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Mesonet demonstration major convective features are similar. Humidity soundings are compared at dry (+) and moist (*) locations [MacDonald et al., Mon. Wea. Rev. (in press) 2001].

If forecast impact is large, regional mesonets could be instrumented


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Summary major convective features are similar. Humidity soundings are compared at dry (+) and moist (*) locations [MacDonald et al., Mon. Wea. Rev. (in press) 2001].

  • Simulations show that GPS slant data can be used for high resolution humidity analysis

  • We plan to assimilate simulated and real data to determine the impact on mesoscale forecasts

  • If the impact is significant, regional mesonets could be instrumented for demonstration experiments


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Points of contact major convective features are similar. Humidity soundings are compared at dry (+) and moist (*) locations [MacDonald et al., Mon. Wea. Rev. (in press) 2001].

  • Jon Case [email protected] 321 853-8264

  • John [email protected] 321 853-8202

  • Yuanfu [email protected] 303 497-6846

  • Randolph [email protected] 303 497-8005

  • Teresa Van [email protected] 303 497-8023


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