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Applications of GPS Radio Occultation Data to Weather and

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Applications of GPS Radio Occultation Data to Weather and Powered By Docstoc
					Use of GPS Radio Occultation Data for
Climate Monitoring


        Y.-H. Kuo, C. Rocken, and R. A. Anthes
    University Corporation for Atmospheric Research
GPS Occultation
          Basic measurement principle:

          Deduce atmospheric properties based on
          precise measurement of phase delay and amplitude.
Radio occultation for Climate
                Radiosonde Stations and Manufacturers




 Vaisala/Australia
  IM-MK3/India
   Shang/China
  MEISEI/Japan
Mars/MRZ       VIZ
        AIR
      Others




                         From Junhong Wang
Quantifying Regional Differences
     Calculate the mean absolute difference in refractivity between
      CHAMP and Radiosondes (NCR) between 5 ~ 25 km.

     Calculate the corresponding mean of the absolute value of the
      difference in refractivity between CHAMP and the ECMWF (NCE)

     Perform calculation using radiosonde data from different regions of
      the world from June 2001 to March 2004.




          From D.Rossiter (UCAR Summer Student)
Statistics of CHAMP - Radiosonde Comparison


                             Average # of   N CR /S.D.   N CE /S.D.
     Region     Sonde Type
                               matches
                                            (%)          (%)
     India       IM-MK3           87        0.82/3.2      0.15/1.0


     Russia       Mars          1003
                                            
                                            0.30/1.3     0.09/0.9


     Japan        MEISEI         107        0.26/1.7      0.14/1.1


     China      Shanghai         402         0.19/1.4     0.15/1.0


    Australia    Vaisala         366         0.18/1.3     0.13/0.9

 Fractional Refractivity Differences between 5 ~ 25 km
Climate change to doubling CO2
   Perhaps the most accurate
    and stable global
    thermometer for estimating
    climate change
   Most accurate where model-
    predicted temperature
    changes are large in upper
    troposphere and lower
    stratosphere


                                 Meehl et al. 2000, J. Climate.
GPS - NCEP/NCAR reanalysis refractivity difference at 300 mb
                                             Northern Hemisphere
GPS - ECMWF analysis refractivity difference at 300 mb

                                                     Northern Hemisphere
GPS - radiosonde refractivity difference at 300 mb
                                    Northern Hemisphere
GPS - NCEP/NCAR reanalysis refractivity difference at 300 mb
                                            Southern Hemisphere
GPS - ECMWF analysis refractivity difference at 300 mb

                                                     Southern Hemisphere
GPS - radiosonde refractivity difference at 300 mb
                                    Southern Hemisphere
Temperature change as detected by GPS RO


300 mb
Temperature change as detected by GPS RO


50 mb
Temperature change as detected by GPS RO


10 mb
COSMIC (Constellation Observing System for
Meteorology, Ionosphere and Climate)
 6 Satellites launched in late 2005
 Three instruments:
  GPS receiver, TIP, Tri-band beacon
 Weather + Space Weather data
 Global observations of:
  Pressure, Temperature, Humidity
  Refractivity
  Ionospheric Electron Density
  Ionospheric Scintillation
 Demonstrate quasi-operational GPS limb sounding with global
  coverage in near-real time
 Climate Monitoring
GPS radio occultation missions
 Mission      Launch-Duration   # Soundings/day   Remarks
 GPS-MET      4/1995    2+             ~125       Proof of Concept

 CHAMP        11/2000   ~5             ~250       Improved receiver, tracking


 SAC-C        11/2000   ~3             ~500       Improved receiver, open loop
                                                  tracking test
 GRACE        5/2002    ~5             ~500       RO data not yet available

 COSMIC       9/2005    ~5          2500 - 3000   Real time-ops

 TerraSAR-X   7/2005    ~5             ~400       COSMIC RX & Antennas

 EQUARS       7/2006    ~3             ~400       COSMIC RX & CHAMP
                                                  antennas
 METOP        5/2007    ~5             ~500       Real time - ops

 COSMIC II    3/2009    ~5          2500 - 3000   Real time-ops. Ionosphere
              Distribution of GPS Occultation events in 24 hrs with
              EQUARS (2006, inclination angle<20o) and COSMIC
              (2005, 6 LEO satellites at 72o)

                                                                      COSMIC
EQUARS




                                          +
    Dense data rate in
    equatorial region                                                 Global coverage,
                                                                      but less data at
                                                                      low latitudes




                                           o: EQUARS
                                           o: COSMIC

				
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posted:2/19/2013
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