New Satellite Capabilities and Existing Opportunities

Bill Kuo1 and Chris Velden2

1 National Center for Atmospheric Research2 University of Wisconsin

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

CHAMP - radiosonde comparison

India Australia

CHAMP - ECMWF Comparison

India Australia

COSMIC (Constellation Observing System for Meteorology, Ionosphere and Climate)

6 Satellites launched in early 2006 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

COSMIC sounding distribution in a day

COSMIC Data Analysis New GPS “Open Loop” (OL)

tracking firmware was implemented and tested on SAC-C satellite

Initial OL results indicate: – Setting and Rising occultations are

working

– No more instrumental bias in the lower troposphere

– >50% of soundings penetrate into lowest km

Additional improvements are possible and currently discussed with JPL

First GPS rising occultation that was inverted at UCAR,with raw data provided by JPL

COSMIC GPS RO Soundings in 24 h over the Pacific

A Short Summary COSMIC will be launched in early 2006, and will produce ~2,500

GPS RO soundings per day, uniformly distributed around the globe. COSMIC is expected to last for 5 years (2006 ~ 2011).

New signal tracking algorithm (open-loop tracking) has shown real promises for much improved soundings in the lower troposphere (remove negative bias, deep penetration).

GPS RO soundings have very high accuracy and very high vertical resolution (great for detecting upper level disturbances).

Loci of GPS RO soundings can be predicted two weeks in advance (very useful for experiment planning).

Many more missions are being planed beyond COSMIC. GPS RO technique is here to stay (so we better learn how to use the data effectively).

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 3/2006 ~5 2500 - 3000 Real time-ops

RoadRunner

USAF

11/2005 ~1+

(slated, Falcon LV)

~350 Spacecraft in Test – waiting on rocket and next years fiscal dollars

TerraSAR-X, German 8/2006 ~5 ~400 COSMIC RX & Antennas

EQUARS

Brazilian/Japanese

~ 2009 ~3 ~400 COSMIC RX & CHAMP antennas, funding not yet secured by INPE,

METOP 5/2007 ~5 ~500 Real time - ops

COSMIC II 3/2009 ~5 2500 - 3000 Real time-ops. Ionosphere

o: EQUARSo: COSMIC

Distribution of GPS Occultation events in 24 hrs with EQUARS (2009, inclination angle<20o) and COSMIC (2006, 6 LEO satellites at 72o)

EQUARS

Dense data rate in equatorial region

COSMIC

Global coverage, but less data at low latitudes

+

Space - based GOS

KALPANA (India) &