The COSMIC/FORMOSAT-3 Mission: Overview and Status

Y.-H. Kuo, R. Rocken, R. A. AnthesUCAR

Nick Yen, J. J. MiauNSPO

COSMIC (Constellation Observing System for Meteorology, Ionosphere and Climate) 6 microsatellites launched in April 2006

Three instruments:GPS receiver, TIP, Tri-band beacon

All six spacecraft are operating

Produced GPS RO soundings:-1.5M neutral atmospheric profiles-1.7M ionospheric profiles-1,500 ~ 2,000 soundings per day

952 registered users from 49 countries

90% of the soundings delivered within 3hA Joint Taiwan-U.S. Mission FORMOSAT-3 in Taiwan

Operational NWP applications

• Global NWP centers began operational assimilation of COSMIC within a year, and have all shown positive impacts.

• Results from ECMWF showed that COSMIC can be assimilated without bias correction:– Serve as anchor for variational bias correction

system– Improve the use of other satellite microwave and

IR sounder data

Climate applications

• “GPS-RO observations and derived products have some unique properties and potentials that are very appealing from a climate perspective” – consensus of NOAA ad hoc GPS-RO Workshop group

• Error characterization – comprehensive and well-documented (e.g., Kursinski, 1997)

• Low structural error – different processing centers produced essentially the same results.

• High vertical resolution, global uniform sampling • High precision and accuracy in the upper troposphere-

lower stratosphere

Support atmospheric research from boundary to stratosphere

• COSMIC data have been shown to be useful for the detection of atmospheric boundary layer, and its spatial and temporal variations.

• COSMIC has been shown to be valuable for detecting systematic biases in different types of radiosonde systems. This is useful for both operational analysis and climate reanalysis.

• COSMIC is showing extremely sharp tropopause inversion over the polar regions, providing opportunities to study the tropopause dynamics.

Weather and space weather• COSMIC data are being used to evaluate thermosphere

(near 300 km) simulations by TIEGCM and other ionospheric models. This is important for space weather forecasting.

• COSMIC has been shown to have a significant impact on the analysis and prediction of significant weather systems:- Hurricane genesis - Intensity and track of tropical cyclones- Mesoscale convective systems during Mei-yu season- Moisture transport associated with East Asia monsoon- Atmospheric river events

Distribution of heights of strong inversion layers(BAL > 1E-2 rad) over North America

Winter:- fewer strong inversion layers over continent, more over the ocean southwards- shallower ABL over continent- deeper ABL over the ocean than in Summer

Summer:most sharp inversion layers(pronounced ABL top)over the ocean and plains;less over mountains

From Sergey Sokolovskiy

5127

day night

day night

Russia

USA

COSMIC-Radiosonde COSMIC-Radiosonde

Russia

USA

Slide 15

From Ben Ho

Neutral Winds derived from COSMIC Data

Luan, X., and S. C. Solomon, Meridional winds derived from COSMIC radio occultation measurements in winter, J. Geophys. Res., in press, 2008.

Arctic summer tropopause inversion layer(from Bill Randel)

• Persistent feature, observed in almost all profiles during summer in both hemispheres (why?)

• Important for understanding dynamical (and chemical) coupling between troposphere and stratosphere

Radiosonde at Eureka (80o N)

inversion~ 8 K

Static stability

high stabilitylayer

Radiosondes and nearby COSMIC soundings

COSMICsonde

sonde-COSMICseparation

COSMIC allows ~100 times more observations than radiosondes, to study space-time variability of inversion layer

Strength of polartropopauseinversion

T(ztrop+ 2km) - T(ztrop)

Daily data from COSMIC,average over polar cap

COSMIC 60o – 90o N

COSMIC 60o – 90o S

Arctic

Antarctic

Summer maximum

7 K

7 K

Bias correction applied toAMSU-A radiances forAugust 2007

Green = ControlPink = COSMIC

Bias correction appliedto channels 8,9,10,11generally smaller with COSMIC assimilated.

Larger for channels12,13.

From Sean Healy, Dick Dee, ECMWF

Fit to radiosonde and COSMIC measurements (SH)

Radiosonde temperature

Bending angleCOSMIC-4

(normalised O-Bdepartures)

CONTROL: redCOSMIC: black

Introduction of COSMIC measurements into ERA-Interim (Dec 12, 2006)