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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.
Radiosonde Stations and Manufacturers
Vaisala/Australia Vaisala/Australia
IM-MK3/IndiaIM-MK3/India Shang/China Shang/China MEISEI/JapanMEISEI/Japan
Mars/MRZ Mars/MRZ VIZVIZ AIR AIR
OthersOthers
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
RegionSonde Type
Average # of 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
€
NCR /S.D.
(%)
€
NCE /S.D.
(%)
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.
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, HumidityRefractivityIonospheric Electron DensityIonospheric Scintillation
Demonstrate quasi-operational GPS limb sounding with global coverage in near-real time
Climate Monitoring
GPS radio occultation missionsMission 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