GPS Atmosphere Sounding, COPS/GOP, April 10, 2006

GPS Atmosphere Sounding

J. Wickert, G. Dick, G. Gendt, M.Ramatschi, and M. Rothacher

GeoForschungsZentrum Potsdam

GPS Atmosphere Sounding, COPS/GOP, April 10, 2006

From „Errors“ to signalsFrom „Errors“ to signals

GPS receivers at the ground and aboard satellites

Atmospheric excess phase (optical phase length) Bending angle

N

snd

snd

GPS Atmosphere Sounding, COPS/GOP, April 10, 2006

Ground basedGround basedsoundingsounding

GPS Atmosphere Sounding, COPS/GOP, April 10, 2006

Result: Zenith Path Delay (ZPD) (with mm accuracy)

PWV = Π (Tm) • ZWD

ZHD = f (Press) [±1 mm accuracy]

ZPD = ZHD + ZWD

dry, hydrostatic wet

Additional data: pressure and temperature at the station

Additional parameter: gradients (North-South, East-West); new: slants

Θ

isotropic water vapor distribution &

known 'mapping'-Function(~1/sin Θ)

Ground based GPS

GPS Atmosphere Sounding, COPS/GOP, April 10, 2006

GPS ground networksGPS ground networks

Global (Analysis of ~ 180 stations at GFZ)

GPS Atmosphere Sounding, COPS/GOP, April 10, 2006

GPS ground networksGPS ground networks

Regional densified (e.g., Germany, ~250 stations in near-real time)

GPS Atmosphere Sounding, COPS/GOP, April 10, 2006

Comparison of GPS-IWV withWVR, RS and LM at Potsdam/Lindenberg

GPS Atmosphere Sounding, COPS/GOP, April 10, 2006

Satellite basedSatellite basedsoundingsounding

GPS Atmosphere Sounding, COPS/GOP, April 10, 2006

CHAMP (since 2000) GRACE (since 2002) TerraSAR-X (launch 2006/7)

Metop (launch June 30, 2006)COSMIC (6; launch April 14, 2006)

GPS aboard satellites for occultationsGPS aboard satellites for occultations

GPS Atmosphere Sounding, COPS/GOP, April 10, 2006

Vertical structure of the atmosphereVertical structure of the atmosphere

•Global, very precise, high vertical resolution

•All-weather, calibration free

GPS Atmosphere Sounding, COPS/GOP, April 10, 2006

National NRT occultation projectNational NRT occultation project

Continuous provision and usage of NRT RO data together with weather prediction centers ECMWF, DWD and Metoffice

Goals:

•provision of NRT RO data (~2h latency

•assimilation to NWP (impact studies)

•real assimilation to NWP planned

other user are invited to use NRT data

GPS Atmosphere Sounding, COPS/GOP, April 10, 2006

Our contribution to Our contribution to COPS/GOPCOPS/GOP

GPS Atmosphere Sounding, COPS/GOP, April 10, 2006

GPS ground stations for COPS/GOPGPS ground stations for COPS/GOP

•~60-70 stations in the region

•Integrated WVP (IWV)

•slants

•Near-real time provision (30-45 min delay)

•15 min resolution in time

•1-2 mm accuracy

GPS Atmosphere Sounding, COPS/GOP, April 10, 2006

+ 5 additional GPS ground stations

• Dry room

• Power supply

• Internet (optional)

Shoke ring antenna

Receiver+laptop