Hyperspectral Infrared Alone Cloudy Sounding

1
Hyperspectral Infrared Alone Cloudy
Sounding Algorithm Development
Elisabeth Weisz_at_, Jun Li_at_, Chian-Yi Liu_at_,
Hung-Lung Huang_at_, and Mitchell D.
Goldberg _at_Cooperative Institute for
Meteorological Satellite Studies (CIMSS),
University of Wisconsin-Madison NOAA/NESDIS
Center for Satellite Applications and Research
Comparison IASI with current GOES Sounder
Comparison with Model Analysis Fields

• Retrieval Methodology
• The retrieval method is based on eigenvector
  regression.
• Clear Radiances for a training set of 15000
  profiles are calculated using SARTA forward model
  (developed by UMBC) for 11 scanning angles.
• Cloudy Radiances for a training set of 2100
  (ice clouds) and 4000 (water clouds) profiles
  are calculated using a fast cloudy radiative
  transfer model (developed in collaboration with
  the Texas AM University)
• For both clear and cloudy calculations radiances
  are computed for 11 scanning angles. Surface
  pressure and the solar zenith angle are used as
  additional predictors.
• In the retrieval step clear sky coefficients are
  applied if the footprint is identified as clear
  (using IR cloud mask and phase mask technique),
  otherwise the cloudy coefficients are applied.
• The retrieval product includes 101 levels of
  temperature (T), humidity (Q), and ozone (O3), as
  well surface skin temperature and eigenvector
  coefficients of the IR surface emissivity
  spectrum. Under cloudy conditions cloud top
  pressure (CTP) is retrieved as well. For
  optically thick clouds soundings are derived only
  above the clouds. For GOES comparisons severe
  weather indices (e.g. LI, CAPE) are computed as
  well.

IASI and ECMWF Moisture
AIRS and NCEP Temperature
Left AIRS temperature retrieval (top) and NCEP
gdas1 temperature along one scanline through
hurricanes Isabel eye (09-13-2003). Difference
between inside the hurricane eye and the
surrounding can be as large as 20 K. Right IASI
humidity retrieval (top) and ECMWF analysis for
05-02-2007 along one line of footprints. Narrow
weighting functions due to the high sampling rate
correspond to finer vertical resolution in the
retrieval and enable the depiction of features of
small extent.
Comparison with Sondes
AIRS RTV, IASI RTV vs. ARM-SGP RAOB
AIRS RTV vs. ARM-SGP RAOBs

• Objective and Summary
• To prepare for the synergistic use of data from
  the high-temporal resolution ABI (Advanced
  Baseline Imager) on GOES-R and hyperspectral
  sounders on polar-orbiting satellites a retrieval
  algorithm has been developed to obtain sounding
  profiles under all weather conditions.
  Hyperspectral IR sounding products are important
  to meet future NWP requirements (e.g. depict
  moisture variations, improve weather/hurricane
  forecasting, detection of low level inversions).
• This poster describes an algorithm to retrieve
  sounding profiles simultaneously with cloud
  properties from hyperspectral infrared (IR) alone
  measurements at single field-of-view (FOV)
  resolution. The algorithm was first successfully
  applied on radiances from the Atmospheric
  Infrared Sounder (AIRS), and preliminary results
  using IASI (Infrared Atmospheric Sounding
  Interferometer) data further demonstrate its
  potential.
• Evaluation of the products have been conducted
  using co-located radiosonde observations, ECMWF
  analysis data, and products from other
  instruments (e.g. GOES, MODIS).
• Future tasks include more validation,
  improvement of regression training set and cloud
  mask algorithm, and physical retrieval
  development.

CIMSS is preparing real-time computation of
various parameters like lifted index (LI),
convective available potential energy (CAPE),
total precipitable water (TPW), and total column
ozone (TCO) under clear skies, as well as CTP
under cloudy conditions, from IASI radiances over
the continental US to be compared with current
GOES sounder products. As an example we show TCO
in Dobson Units retrieved from GOES (top, large
scale view, from http//cimss.ssec.wisc.edu/goes/r
ealtime/) and IASI (bottom) for 10-02-2007 (1700
UTC). In general TCO retrieved from GOES and IASI
agree well.
Left AIRS clear-only (black) and cloudy (red)
retrieval of temperature and relative humidity
compared with two radiosondes (green, blue) at
the ARM-SGP site on 12-15-2006, with retrieved
CTP 320 hPa. Right Temperature, dew point
temperature and relative humidity from radiosonde
(green), IASI retrieval (red) and AIRS retrieval
(blue) at the ARM-SGP site on 05-02-2007. Above
the cloud (retrieved CTP from AIRS is shown as
thin gray line) both retrievals correspond well
to the radiosonde measurement. Differences might
also be due to temporal differences between the
observations.
Acknowledgements. This project is partially
supported by NOAA GOES-R programs at
CIMSS. Contact. elisabeth.weisz_at_ssec.wisc.edu