COST 723 Meeting – Berne, October 6-7, 2003

GPS RADIO OCCULTATIONS WITH CHAMP:TEMPERATURE MEASUREMENTS IN THE

UTLS REGION

T. Schmidt, J. Wickert, G. Beyerle, and C. Reigber

 GeoForschungsZentrum (GFZ) Potsdam

Department 1: Geodesy & Remote Sensing

COST 723 Meeting – Berne, October 6-7, 2003

Introduction

Radio occultation measuring principle

Data base and quality

Applications

Summary

Overview

COST 723 Meeting – Berne, October 6-7, 2003

Launched on July 15, 2000 at Plesetsk (Russia)

Mission duration: 6-7 years

Orbit: eccentricity=0.004

inclination=87.2°

initial altitude=454 km

CHAMP Launch

Determination ofEarth‘s gravity,

magnetic field andglobal sounding of Earth‘s

atmosphere

COST 723 Meeting – Berne, October 6-7, 2003

Radio Occultation Geometry

COST 723 Meeting – Berne, October 6-7, 2003

Carrier Phases & SNRDouble

Differencing

Atmospheric Excess Path

Derivation ofBending Angle

Bending Angle Profile

Refractivity Profile

Abel Inversion

IonosphericCorrections

Dry TemperatureWater Vapour

ProfilingWet Air Profiling

Dry Air

Temperature fromMeteorological

Analyses

Precise Orbit Data

Occultation Data Analysis

COST 723 Meeting – Berne, October 6-7, 2003

Earth

Radio Occultation Technique: Characteristics

Global coverage

High vertical resolution

Long-term stability

All-weather viewing

COST 723 Meeting – Berne, October 6-7, 2003

Global distribution

Feb - Dec 2001 (11 months) ~35.000 occultations

COST 723 Meeting – Berne, October 6-7, 2003

CHAMP vs. ECMWF

0.5

0.50.5

0.0

0.00.0

-1.0

-0.5

COST 723 Meeting – Berne, October 6-7, 2003

CHAMP vs. Radiosondes May 2001 – July 2003

d < 300 kmt < 3 h

Radiosonde data from FU Berlin

COST 723 Meeting – Berne, October 6-7, 2003

2001 2002 2003

2001 2002 2003

Lapse-rate tropopause altitude

Lapse-rate tropopause temperature

CHAMP tropopause parameters

COST 723 Meeting – Berne, October 6-7, 2003

CHAMP tropopause parameters (10S-10N)

0.4 hPa-4.9 hPa-1.3 hPa

0.5 K-4.2 K-1.2 K

COST 723 Meeting – Berne, October 6-7, 2003

CHAMP 2001-2003

COST 723 Meeting – Berne, October 6-7, 2003

Temperature anomaly over equator

COST 723 Meeting – Berne, October 6-7, 2003

Summary

Since February 2001 CHAMP radio occultation experiment activated on more than 830 days (more than 116.000 profiles of refractivity, temperature available)

CHAMP provide high vertical resolution temperature profile data

Good agreement with ECMWF and radiosondes in upper troposphere and lower stratosphere (300 – 30 hPa):

Temperature bias <1 K

Temperature RMS deviation 1–2 K

CHAMP in excellent condition, mission expected to last until 2007

COST 723 Meeting – Berne, October 6-7, 2003

GPS radio occultation missions

1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010

GPS / MET

SAC-C

COSMIC

METOP

6

3

CHAMP

GRACE

GFZ Potsdam

pioneering

NPOESS 3

1

2

# Sats

ACE+ / SWARM (3-6)

TerraSAR-X 1

1