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GPS Radio-Occultation data (COSMIC mission)

GPS Radio-Occultation data (COSMIC mission). Lidia Cucurull NOAA Joint Center for Satellite Data Assimilation . COSMIC (Constellation Observing System for Meteorology, Ionosphere and Climate).

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GPS Radio-Occultation data (COSMIC mission)

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  1. GPS Radio-Occultation data (COSMIC mission) Lidia Cucurull NOAA Joint Center for Satellite Data Assimilation

  2. COSMIC (Constellation Observing System for Meteorology, Ionosphere and Climate) • 6 Satellites launched in April 15 2006 • Three instruments: • GPS receiver, TIP, Tri-band beacon • Demonstrate quasi-operational • GPS limb sounding with global • coverage in near-real time • Climate Monitoring • web page: www.cosmic.ucar.edu

  3. GPS Occultation Basic measurement principle: Deduce atmospheric properties based on precise measurement of phase delay and amplitude.

  4. Characteristics of GPS RO Data • Limb sounding geometry complementary to ground and space nadir viewing instruments • High vertical resolution (0.1 km surface - 1km tropopause) • Lower horizontal resolution (~300 km) • High accuracy (equivalent to < 1 deg K from 5-25 km) • All weather-minimally affected by aerosols, clouds or precipitation • Independent of radiosonde calibration • No instrument drift • No satellite-to-satellite observational bias

  5. GPS radio occultation measurements & processing Raw measurements of phase and amplitude of L1 and L2 s1, s2, a1, a2 Radio holographic method, Multi path Bending angles of L1 and L2 Spherical symmetry & Satellites orbits. a1, a2 Bending angle Single path a s1, s2 Refractivity Ionospheric effect cancellation N climatology Raw measurements of phase of L1 and L2 T, e, P Auxiliary meteorological data

  6. Forward Models: Refractivity: Bending angle:

  7. COSMIC - Status • COSMIC became operationally assimilated at NCEP on May 1st 2007, along with the implementation of the new NCEP’s Global Data Assimilation System (GSI/GFS). • Profiles of refractivity were selected for implementation in operations, while the tuning of the assimilation of bending angles is currently being analyzed at NCEP. • Several impact studies for selected periods show a positive impact in model skill when COSMIC profiles are assimilated on top of the conventional/satellite observations. • UCAR Post-processing GPSRO data from CHAMP (one satellite, ~ 2001) and COSMIC (six satellites) missions can be made available for CFSRR.

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