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Tropospheric Emission Spectrometer (TES) Retrievals in the Presence of Clouds

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Thanks to Ming Luo, Robert Herman, Kevin Bowman, Tony Clough, and the TES science team ... L. and S.A. Clough (1997): Accelerated monochromatic radiative ... – PowerPoint PPT presentation

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Title: Tropospheric Emission Spectrometer (TES) Retrievals in the Presence of Clouds


1
Tropospheric Emission Spectrometer (TES)
Retrievals in the Presence of Clouds
Susan Sund Kulawik, John Worden, Annmarie
Eldering Thanks to Ming Luo, Robert Herman,
Kevin Bowman, Tony Clough, and the TES science
team Earth Space Sciences Division The Jet
Propulsion Laboratory California Institute of
Technology Pasadena, CA AER, Massachusetts Rayth
eon ITSS, Pasadena
2
COMPARISON TO FORMER APPROACHES
Other instruments retrieve atmospheric parameters
with clouds. AIRS, TOMS, OMI, MOPITT
successfully retrieve in the presence of clouds
TESs approach is somewhat different than prior
approaches 1) Parameterize clouds and place the
effect of these parameters into our forward
model 2) Retrieve cloud parameters like any other
retrieved parameter, with an initial guess, a
priori, constraint, and Jacobians 3) Error
characterization and effect of clouds on
retrieved atmospheric species is handled like any
other retrieved parameter
3
TES CLOUD PARAMETERIZATION
  • Single cloud layer modeled as a Gaussian profile
  • Absorption and scattering modeled with an
    effective tau discretized on a coarse frequency
    grid 25 100 cm-1

Altitude
layer thickness
Effective extinction (25 frequency values)
width parameter (fixed)
4
TESTING TES CLOUD ASSUMPTIONS
  • Comparing the TES forward model with clouds to
    CHARTS (includes cloud scattering)

650 900 cm-1
990-1065 cm-1
1200 1320 cm-1
Moncet, J.-L. and S.A. Clough (1997)
Accelerated monochromatic radiative transfer for
scattering atmospheres Application of a new
model to spectral radiance observations. J.
Geophys. Res., 102, 21,853-21,866.
5
TES / CHARTS zoom in 1172-1213 cm-1
ELANOR,
ELANOR,
ELANOR,
6
TESTING TES CLOUD ASSUMPTIONS
  • Clouds of all heights and optical depths can be
    adequately modeled
  • with effective extinction and cloud altitude to
    within TES data noise


Moncet, J.-L. and S.A. Clough (1997)
Accelerated monochromatic radiative transfer for
scattering atmospheres Application of a new
model to spectral radiance observations. J.
Geophys. Res., 102, 21,853-21,866.
7
CHARACTERIZING / VALIDATING CLOUD EFFECTS ON
TRACE GASES
  1. Test cases of simulated data with variety of
    thin, thick, and double layer clouds
  2. Retrieve CHARTS radiances using TES retrieval
    algorithm
  3. Compare results and predicted errors to known
    truth

High clouds
High clouds
No clouds
Double-layer
Low, thick clouds

Prepared cloud cases
Moncet, J.-L. and S.A. Clough (1997)
Accelerated monochromatic radiative transfer for
scattering atmospheres Application of a new
model to spectral radiance observations. J.
Geophys. Res., 102, 21,853-21,866.
8
Ozone retrieved column in various SIMULATED cloud
cases
  • Improvement over initial guess
  • Trend of errors with cloud O.D. is small

Total Ozone Column by Target
High clouds
Double-layer
No clouds
Low clouds
High clouds
Tropospheric Column Error
Total Column Error
9
TES reported errors are reliable with clouds
  • Predicted and actual errors match over this
    ensemble of simulated cases
  • Improvement over the initial error

10
REAL DATA! TES TATM compares well to AIRS and
GMAO
  • Matched target scenes between TES and AIRS or
    GMAO
  • Compare average temperature between 825 and 100
    mb
  • No apparent cloud-dependent bias for TES, GMAO,
    or AIRS
  • See A. Elderings talk for detailed TES/AIRS
    Temperature comparisons

TES vs GMAO (used as TES a priori)
TES vs AIRS
Ave 1.2 K bias
Ave 0.6 K bias
11
REAL DATA! O3 comparison to TOMS independent of
clouds
  • No apparent change in bias depending on clouds
    for TES vs. TOMS
  • See G. Ostermans talk / poster for more
    detailed TES comparisons to TOMS

12
TES sensitivity through clouds
  • We look at TES sensitivity for ozone below clouds
    of varying optical depths.
  • TES sensitivity determined by degrees of freedom
    ?(Averaging Kernel)ii.
  • Cloud O.D.(lt500 mb) DOF (gt500 mb) TES
    Sensitivity
  • 0 0.8 100
  • 0.1 0.5 60
  • 1.0 0.25 30
  • Conclusion We do see below clouds and have 30
    sensitivity (relative to clear-sky) below an
    effective O.D. 1.0 cloud.

13
TES Special Observation Nadir Step Stare for
Nov 3, 2004 (150 observations from 1N to 65N)
D (Northwest Territories)
TES Ozone
C (South Dakota)
B (Oklahoma)
TES Water
A (Yucatan)
The AIRS-visible images (left) show the TES
footprint locations (blue) over a variety of
cloud and surface conditions. The TES retrievals
for this Step Stare are shown for ozone and
water with the TES retrieved cloud effective
optical depth and height shown with gray circles.

14
CONCLUSIONS
  • TES cloud parameterization results in forward
    model errors below TESs data noise level
  • TES retrievals of trace gases in the presence of
    clouds are well characterized with reliable error
    estimates
  • TES retrievals with real data agree with AIRS,
    TOMS, and GMAO independently of the presence or
    absence of clouds
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