Minutes of the fourth International Radiative Transfer Workshop,
July 2002
Monday
Tuesday
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-----===== TUESDAY 2002-07-09 =====-----
a) Intercomparison paper
The model named as MAES is in named in the plots as CRL and ss
as FIP
1. case 0
- Nikolay is giving description of the cases
- Moliere uses Kuntz implementation of the Voigt function.
- DLR is not using the partition function but some software
called ATMOS so the line strength can be different.
Franz is giving a short description of line strength
calculation by ATMOS.
* comment from Franz:
+ Kuntz is simply an optimized version of the Humlicek algorithm to
compute the Voigt profile / complex error function (Voigt=Re(cerf))
In general I use Humlicek as well, just with a different optimization.
for most of the case0 and 1 calculations submitted to Bremen, however,
I used the wofz code of Poppe&Wijers which (according to the authors)
has an accuracy of 14 significant digits (Humlicek: 10^(-4)).
+ My line strength conversion is done according to the scheme
described in Norton&Rinsland:
@article{Norton91,
AUTHOR = {R.H. Norton and C.P. Rinsland},
TITLE = {ATMOS data processing and science analysis methods},
JOURNAL = AO,
VOLUME = 30,
PAGES = 389,
YEAR = 1991}
ATMOS is a FT spectrometer flown several times on the space shuttle.
Atmospheric Trace Molecule Spectroscopy Experiment
http://remus.jpl.nasa.gov
2. case-1A
- Similar results as case0 except for FIP.
- Karlsruhe also uses ATMOS scheme for partition function
3. case-1B
- MPM-93 has lot of discrepancies.
4. case-2
- Karlsruhe uses O2-Liebe98 model, so it can be the reason for
discrepancy
- Moliere uses MPM-93 for oxygen and nitrogen.
- SMILES simulator is showing large discrepancy at higher alt.
5. case-3 Down
- DLR and Moliere participate
- coarse pressure grid and fine pressure grid:
differences are some Kelvin (see paper)
6. case-3 Limb
- In comparison with ARTS and MIRART ARTS is missing the
peak(FS).
- Deadline of the paper: August(to finalize the models and cases)
and September(to do the final iteration of the results).
- Wednesday there will be meeting people for each groups.
AMIL2DA(FS)
- Advanced MIPAS level 2 analysis (EU_FP5 project)
- www.fzk.de/imk/imk2/ame/amil2da
- main question:
Are MIPAS level 2 data processed by different institutes/processors
comparable?
- Strategy:
1. forward radiative transfer model intercomparison
2. blind-test retrievals using synthetic spectra
3. intercomparison of retrievals with real mipas data
- Forward models:
KOPRA (Karlsruhe), OFM (IROE, Florence), RFM (Oxford),
MIRART (FS), FM2D (RAL)
- In the intercomp. 30 exercises each with only one spectra at one
frequency range starting from simple settings and proceeding to
more complex/realistic cases.
- non LTE implementation is also checked (Kopra and RFM only)
- KOPRA is taken as the reference model
- Transmission: large difference in the CO2 2400 - 2500 cm-1
region (4 micrometer),
250mb, 256 K was coming from different line rejection criteria.
- Radiance (incl. ILS and FoV effects):
deviations for all models less than 1%
- Blind test retrieval - first results:
all codes giving reasonable/consistent results for ozone etc.
Zeeman Splitting(NK)
- contact Nikolay
- Yasuko told BrO and ClO also has small Zeeman splitting
- Ozone??
RT through the atmosphere of other planets(JU)
- Moliere
- MAMBO - MARS ATMOSPHERIC MICROWAVE BRIGHTNESS TEMPERATURE
EXPLORER, Limb looking
- Launch will be in sept 2007, Ariane5, arrival 2 years later
- present and past Martian atm, temperature and winds, general
circ, water cycle(0-60 km), photochemical state- CO, H2O2,
surface(polarisation)
- profiles H20 seasonal variation, temperature is decreasing
with altitude
- nadir operations also
- Moliere is used to calculate spectra
- wind is measured by Doppler shift in the CO line
- Instrument description
- different data levels upto level 4
- mars radius - 3397?
- ground pressure - 7hpa
- H20 and CO2 continuum are implemented
- LTE can be used???
- surface emissivity can be a problem
- strong variability of H2O can be a problem in the retrieval
- retrieval of the temperature from two CO isotopes
- for H2O 5 km grid is used
- The first test retrievals shows temperature and water vapor
can be retrieved, spectroscopy part is seemed to be more
complicated
Forward modeling in the Visible region(Ute)
- unpolarized source
- Polarisation in remote sensing
- Instruments: reflection, refraction, self polarisation
- picture from POLDER to illustrate the effect of polarisation
- polarising processes in nature:
- UV Rayleigh scattering
- Rayleigh scattering - maximum at 90 degrees
- scattering by cloud particles - degree of polarisation is
very sensible to microphysics of the cloud
- non sphericity can be measured through polarisation
- reflection from sand is slightly polarised.
- moist surfaces polarize more
- polarized light from a canopy is coming from the specular
reflection from the leaf surfaces
- on water surface- Fresnel's law, angle dependence
- ground is modeled as
- for aerosols types and optical thickness are retrieved
ARTS Application
Odin Inversions(PE)
- Odin spectra
- don't get exactly the pointing offset, has to be looked at
Ground based inversions in Sweden(PE)
- plot for measurements
- mesospheric CO is measured
- Vertical profiles of CO above Onsala, a downward transport of
CO is seen
-
SMILES Inversion(CV)
- Instrumental description
- three spectral bands
- very low system noise temperature
- nice spectrum
- temperature retrieval is tried.
- temperature weighting function(with and without HSE)
AMSU Intercomparison(MK)
- AMSU and Lindenberg data
- comparison between ARTS and AMSU
- plots for NOAA 15 and NOAA 16
ARTS for AMSU(VOJ)
-
Outgoing Longwave(SB/PE)
- Balance of incoming and outgoing radiation
- difference of real spectra from black body curve
- plot of sensitivity to double H2O, maximum sensitivity 900
hpa to 300 hpa
- same plot for doubling of CO2, only in a narrow frequency
range
- H2O is more important than CO2.
Tangent Linear and Adjoint Models(CM)
- contact Christian
- R M Errico "What is an adjoint model?" BAMS, 1997
- C D Rodgers, "Inverse Methods for Atmospheric Sounding",
World Scientific, 2000.
- Some web sites
- Adjoint model compiler
- Papers by .... told by Franz.
Go to HTML and PDF version of the presentation.
Retrieval Tool(PE)
- Qpack
- Implemented in matlab and uses ARTS as forward model
- only OEM
- example control file
- How to call functions
- creation of covariance matrices
- Franz:
+ PyReS: 'Python based retrieval system'
+ application: FOCUS, MIPAS, THOMAS,...
+ forward models: MIRART, MODTRAN, .....
(steered by PyReS using appropriate template file)
+ inversion codes: (standard) nonlinear least squares libraries,
Birger Schimpf's Tikhonov regularizatio code, ....
+ NOTE: only partially implemented right now
(currently works for Focus retrievals only)
- Fully integrated systems: forward and inverse programs
together: Moliere, Karlsruhe
Retrieval Error Analysis for Spectroscopic Parameters(CV)
- Rodger's OEM algorithm
- Linear mapping method
- inverse model linearized around a priori state
- OEM method will be better since the error covariance can be
treated as Gaussian
Working Groups
- intercomparison working group will be met and try to figure
out problems regarding writing of the paper
------------
ACTION ITEMS
------------
o Intercomparison paper:
- iup/sat Bremen will unify the plotting style for all the
necessary plots of the paper
- all participants of the intercomparison have to obey the
time schedule for the delivering of the model information
and final data sets.
- main editor (one of the iup/sat Brmen member) of the paper
has to be named by iup/sat Brmen.
- Franz will send the AMIL2DA paper and the template for the
model description used in the AMIL2DA comparison to
iup/sat Bremen.
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