CDAAC ionospheric products and their applications

CDAAC ionospheric products and
their applications
Bill Schreiner, Xin’an Yue, S. Sokolovskiy, C. Rocken,
D. Hunt, Y-H.Kuo
COSMIC Program Office
CDAAC (COSMIC Data Analysis and Archive Center)
UCAR
IRI2009 Workshop Nov 2-7, 2009
Kagoshima, Japan
Outline
  COSMIC and CDAAC Overview
  Scientific research using CDAAC
ionosphere products
  Future Plans
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COSMIC at a Glance
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Constellation Observing System for Meteorology
Ionosphere and Climate
Joint US, Taiwan Mission (FORMOSAT-3)
6 Satellites launched in Apr 2006
Orbits: alt=800km, Inc=72deg, ecc=0, ∆Ω=30deg
GPS Radio Occultation Receiver:
o  Refractivity
o  Pressure, Temperature, Humidity
o  Absolute TEC
o  Electron Density Profiles (EDP)
o  Ionospheric Scintillation (S4 amplitude)
Tiny Ionospheric Photometer (TIP) – Radiances
Tri-Band Beacon Transmitter
Demonstrate quasi-operational GPS limb sounding with
global coverage in near-real time
Climate Monitoring
Useful for many ionospheric studies
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CDAAC Processing Flow
CDAAC File types in RED
Atmospheric processing
atmPhs
LEO data
Level 0--level 1
Excess Phase
Full Spectrum
Abel Inversion
atmPrf
(S4)
1-D Var
Moisture
Correction
wetPrf
Fiducial
data
POD (Orbits
and clocks)
bfrPrf
Real time Task Scheduling Software
Profiles
Ionospheric processing
podTec (TEC)
scnLv1 (S4)
tipLv1 (Radiance)
Excess Phase
Processing
ionPhs
(L1,L2
amp/phase)
Abel Inversion
ionPrf
(EDPs)
Combination
with other data
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CDAAC processing data for these
Radio Occultation missions
COSMIC
GRACE
SAC-C
CHAMP
TerraSAR-X
GPSMET
Metop/GRAS,
others available soon
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By using these CDAAC observations, many scientific
works have been done, including:
1. 
Data comparison and validation
2. 
Model validation
3. 
Ionosphere climatology/Ionosphere weather/space weather
4. 
Topside ionosphere/plasmasphere
5. 
Ionosphere scintillation/Es
6. 
Ionosphere-atmosphere coupling
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Data assimilation and other applications
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……………………….
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Electron Density Profiles
•  Electron Density Profiles, EDPs (level2:ionPrf)
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Number ~2.7M: COSMIC (4/06-9/09: 2.4M), CHAMP (5/01-10/08: 300,000)
Abel Inversion assumes spherical symmetry: Significant inversion errors below F2 layer
NOTE: Fixed COSMIC level0->level1a s/w bug, corrected noisy profiles after 2008.001
Quality Control still needs
improvement
Lei et al.,
2006JA012240
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Unit: 1×105/
Tsai et al. [2009RS004154] constructed a new
EDPs model (TWIM) using COSMIC
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Profile modeling: >2.5 million profiles
Eg. Estimation of IRI profile parameters from COSMIC EDPs
Liu et al., 2008JA013490
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Ionosphere High Transition Height (in progress)
  Method: Assume the diffusion equilibrium of O+ in the topside. Obtain the scale height of
O+ from the profile and then calculate the profile of O+. [Kutiev et al., 2004]
  HTH comparison between COSMIC and C/NOFS observations for the same latitude region
and time period: Lat [-13 13], June-August, 2008
COSMIC
C/NOFS
The maximum of COSMIC HTH during daytime is about 100km lower than C/NOFS (this may
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be related with the error of our method). Note: C/NOFS has a much smaller sample
Absolute TEC Data
•  Absolute TEC (level1b:podTec)
-  Number > 3.2M: COSMIC (4/06-9/09: ~3M),
CHAMP (5/01-10/08: 200,000)
-  NOTE: Fixed COSMIC level1a->level1b s/w
bug and reprocessed 2008.001 onwards
resulting in 700,000 more arcs
-  Absolute accuracy ~ 1-3 TECU,
-  Relative accuracy ~ 0.0024 TECU at 1-Hz
sampling (COSMIC: 2009.001-004)
-  Quality Control is good
COSMIC transionospheric radio links
for a 100-min period,
June 29, 2007
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Ionosphere top-side response to the 15 December 2006
storm by COSMIC podTec
Pedatella et al., 2009
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Ionosphere response to sudden stratosphere warming
(~Jan 20, 2009) seen in topside ionosphere
•  Topside TEC (> 800 km) in the
Deviation (TECU)
vTEC(SSW month) - vTEC(preSSW month)
topside increase in the morning
•  TEC decreases in the afternoon
•  This results agrees with study of
ground-based GPS [Goncharenko et
al. 2009,CEDAR meeting]
•  NEW: Topside TEC is good
evidence that the SSW affects the
ionosphere by changing the tides and
then the electric field in ionosphere
(only EXB can reach high altitude)
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Scintillation Data
•  Scintillation S4 (level2:atmPrf)
-  Computed from 50-Hz Occultation L1 SNR observations (60-80 km alt)
-  Number: COSMIC (4/06-3/09: ~2M), CHAMP (5/01-10/08: 393,000), GRACE
(11/06-3/09: 90,000), GPSMET (5/95-2/97: ~5,000: ~4,000 AS)
•  COSMIC Scintillation S4 (level1b:scnLv1)
-  Downloaded 1-Hz values from all line of sites (based on 50-Hz L1 SNR)
-  Number: > 4.5M LEO-GPS arcs
Scintillation from level1b:scnLv1 (9-sec averages)
E layer
F layer
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Tiny Ionospheric Photometer
•  COSMIC Calibrated TIP radiances (level1b:tipLv1)
-  TIP payload off for FM2/3
-  > 1400 hours of data
Auroral Oval seen both by TIP (left)
and low altitude EDPs (right)
Tsai et al., 2009
COSMIC TIP: 2006-2009, ~1400 hours
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Future plan for the CDAAC:
1. 
Add more satellite missions
2. 
Improve the data retrieval method and data quality control
3. 
Continue to provide free data and more convenient way to get
the data
4. 
Just had 4th FormoSat-3/COSMIC Data Users WS, see website
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COSMIC Data Access
COSMIC Web site http://www.cosmic.ucar.edu
•  Select the 'Sign Up ' link under
COSMIC
•  Accept data use agreement
•  E-mail will be sent within 2-3
business days to indicate
access has been granted
•  Raw Data from multiple missions
•  TEC, EDPs, S4, TIP in NetCDF
format
•  On-line SQL database, analysis tools
and data download
•  Unidata LDM access
http://www.unidata.ucar.edu/Projects/
COSMIC/data_opportunity.html
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Acknowledgments
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NSF
Taiwan’s NSPO
NASA/JPL, NOAA, USAF, ONR, NRL
Broad Reach Engineering
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