Transcript Assimilation and Impact of GPS Radio Occultation data

Earth Observation with COSMIC
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COSMIC at a Glance
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Constellation Observing System for Meteorology Ionosphere
and Climate (ROCSAT-3)
6 Satellites launched in late 2005
Orbits: alt=800km, Inc=72deg, ecc=0
Weather + Space Weather data
Global observations of:
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Pressure, Temperature, Humidity
Refractivity
TEC, Ionospheric Electron Density
Ionospheric Scintillation
Demonstrate quasi-operational GPS limb sounding with global
coverage in near-real time
Climate Monitoring
Geodetic Research
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COSMIC Status
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Figure: T. Yunck
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QuickTime™ and a
Cinepak decompressor
are needed to see this picture.
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Radio occultation for Climate
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COSMIC high resolution profiles
Profile the (sporadic) ionospheric
E-layer with ~1-km vertical resolution
Area dominated by noise - used for noise
calibration of profile
Area affected by noise - profiles are noisy
and/or affected by climatology
Highest quality profiles 5-30 km
Some profiles affected by boundary
layer effects (super refraction)
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GPS RO Minus NCEP 50 mb S. hemisphere
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Climate Change and Geopotential Heights
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Climate change effect on Temperature and Bending Angles
Temperature change due to 2xCO2
Bending Angle change
due to 2xCO2
Radio occultation (RO) bending angles are a potentially better indicator
for a stratospheric climate signal than RO temperatures.
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Climate Research with RO Data
•Investigate potential biases in RO time series
•Investigate use of geopotential height, bending angles, or
refractivity for climate studies
•Climate process studies (Bill Randel’s work)
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GPS Operational Tracking Scenario
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GPS receiver shall measure GPS L1&L2 phase and amplitude for (1) ionospheric
profiling; (2) plasmaspheric monitoring; (3) scintillation studies
POD antennas
@ 1 Hz
Calibrating GPS
Neutral atmosphere
Ground
receiver
10 sec
data
1-s
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Ionosphere
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20 msec
data
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COSMIC S/C
With Antennas
GPS Sat.
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Occulting GPS
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(L
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GPS Sat.
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10 se c dat
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Occulting LEO
Limb Antennas
@ 50-100 Hz
GPS Sat.
Application
Altitude Range
(km)
Antenna
Sampling Rate
(Hz)
Plasmasphere
> 800
POD ant.
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Ionospheric Profiling
140 < Alt < 800
POD ant.
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Ionospheric Profiling and
Scintillation
60 < Alt < 140
Limb ant.
50 - 100
Earth
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Electron Density Profile
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Altitude (km)
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M il ls t o n e ( P L = 4 4 8 ) ,
4 2 .6 N, 7 1 .5 W ,
1 3 :2 8 :0 0 U T C
GP S /ME T, # 0 0 0 3 ,
4 6 .9 N, 5 7 .5 W ,
1 3 :2 9 :3 2 U T C
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P IM ( @ # 0 0 0 3 )
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E l e c tro n D e n s i ty ( 1 / c m ^3 )
1.0E+6
1.0E+5
1.0E+4
1.0E+3
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Vertical Profile of electron density from GPS/MET
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TIP Payload
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TIP measures nighttime FUV emission of neutral atomic
oxygen
TIP and GPS data can be processed together for improved
ionospheric profiling
Radiative recombination: O++e-  O+h
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135.6 nm produced by radiative recombination of O+ ions and
electrons
O+ and e- densities equal in the F-region
135.6 emission intensity proportional to electron density
squared
Simple algorithm relates electron density to 135.6 nm intensity
measured by TIP
Aurora: O+e-  O +e- +h
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135.6 nm produced in aurora through electron impact
excitation
TIP can determine auroral boundaries
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CERTO / TBB Concept
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OBJECTIVE
– Provide Multi-Scale Description of the Ionosphere
• Beacon to Ground Total Electron Content (TEC) using Differential
Phase and Faraday Rotation
• Maps of Structured and Quiescent Plasma Environment Based on
Phase and Amplitude Scintillations
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Description
– Three Frequency Radio Beacon
(150.012, 400.032, 1066.752 MHz)
Radiating Phase Coherent,
Continuous Wave Transmissions
– Differential Phase Receivers on
the Ground Recording Phase and
Amplitude.
– Images Obtained by Tomographic
Processing of Data
Orbit
CERTO Beacon
Irregularity
Receiver
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CDAAC Ionospheric Data Products
Data Level
File Type
Description
File Content
Level0
tbbLv0
CERTO/TBB data file for station
Time, SNR, , S4, station position, LEO orbit, TEC, TEC error
estimates
Level1a
tipLv1
TIP Radiances
Time, LEO pos/vel, pointing, Radiance, Calibration, Radiance error
estimate
Level1b
ionPhs
1 Hz biased TEC file for ionospheric occultations
(altitude > 60km)
Time, SNR, LEO Orbits, GPS Orbits, biased TEC, TEC error
estimate
Level1b
losPhs
1 Hz biased TEC file for non-occulting links
Time, SNR, LEO Orbits, GPS Orbits, biased TEC, TEC error
estimate
Level1b
atmPhs
50 Hz excess phase file for atmospheric occultations
(alt < 140km)
Time, SNR, LEO Orbits, GPS Orbits, L1 excess phase, L2 excess
phase, S4
Level2
ionPrf
Electron Density Profile computed with Abel inversion
Latitude, Longitude, Altitude, Electron Density, ED error estimate
Level2
iocPrf
Electron Density Profile computed with additional TIP
data as constraint
Latitude, Longitude, Altitude, Electron Density, ED error estimate
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Ionospheric Research with COSMIC Data
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We are talking with NCAR HAO to identify COSMIC data products that will be
most beneficial to ionospheric research community
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Calibration/Validation of other ionospheric instruments
Calibration, improvement, and validation of physics based models of ionosphere
Studies of scintillation (plasma bubbles)
Ionospheric climatology
Studies of plasmaspheric depletion and refilling during and after storms
Ionospheric enhancements and depletions during storms
Gravity wave studies
Traveling Ionospheric Disturbances
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Getting COSMIC Results to Weather Centers
NCEP
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BUFR Files
WMO standard
1 file / sounding
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ECMWF
GTS
CWB
UKMO
JMA
Canada Met.
This system is currently under development by UCAR, NESDIS, + UKMO
Data available to weather centers within < 180 minutes
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Summary
•COSMIC is on track to launch in ~1 year
•Will provide data for a wide range of climate, weather and
space weather investigations
•COSMIC data Collaboration on the optimal use of these data at
UCAR/NCAR provide a rich opportunity for our organization
•Hope to identify scientific opportunities and programmatic
approaches to them
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Effects of CO2 increase on climate change simulated by NCAR
Climate System Model (CSM)
Vertical cross sections of zonally-averaged model temperature changes averaged over 20 years (years 60-79) in
NCAR Climate System Model in which carbon dioxide alone is increased by 1% per year (Meehl et al., 1998).
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