New Satellite Capabilities and Existing Opportunities Bill Kuo 1 and Chris Velden 2 1 National Center for Atmospheric Research 2 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 IM-MK3/India Shang/China MEISEI/Japan Mars/MRZ VIZ AIR Others From Junhong Wang

Quantifying Regional Differences n Calculate the mean absolute difference in refractivity between CHAMP and Radiosondes (N CR ) between 5 ~ 25 km. n Calculate the corresponding mean of the absolute value of the difference in refractivity between CHAMP and the ECMWF (N CE ) n Perform calculation using radiosonde data from different regions of the world from June 2001 to March From D.Rossiter (UCAR Summer Student)

Statistics of CHAMP - Radiosonde Comparison RegionSonde Type Average # of matches IndiaIM-MK / /1.0 RussiaMars / /0.9 JapanMEISEI / /1.1 ChinaShanghai / /1.0 AustraliaVaisala / /0.9 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, Humidity Refractivity Ionospheric Electron Density Ionospheric 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 n New GPS “Open Loop” (OL) tracking firmware was implemented and tested on SAC-C satellite n 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 n 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 n 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). n New signal tracking algorithm (open-loop tracking) has shown real promises for much improved soundings in the lower troposphere (remove negative bias, deep penetration). n GPS RO soundings have very high accuracy and very high vertical resolution (great for detecting upper level disturbances). n Loci of GPS RO soundings can be predicted two weeks in advance (very useful for experiment planning). n 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 missions MissionLaunch-Duration# Soundings/dayRemarks GPS-MET4/ ~125Proof of Concept CHAMP11/2000 ~5~250Improved receiver, tracking SAC-C11/2000 ~3~500Improved receiver, open loop tracking test GRACE5/2002 ~5~500RO data not yet available COSMIC3/2006 ~ Real time-ops RoadRunner USAF 11/2005 ~1+ (slated, Falcon LV) ~350Spacecraft in Test – waiting on rocket and next years fiscal dollars TerraSAR-X, German8/2006 ~5~400COSMIC RX & Antennas EQUARS Brazilian/Japanese ~ 2009 ~3~400COSMIC RX & CHAMP antennas, funding not yet secured by INPE, METOP5/2007 ~5~500Real time - ops COSMIC II3/2009 ~ Real time-ops. Ionosphere

o: EQUARS o: COSMIC Distribution of GPS Occultation events in 24 hrs with EQUARS (2009, inclination angle<20 o ) and COSMIC (2006, 6 LEO satellites at 72 o ) EQUARS Dense data rate in equatorial region COSMIC Global coverage, but less data at low latitudes +

Space - based GOS KALPANA (India) &