Minutes of the fourth International Radiative Transfer Workshop, July 2002

Monday   Tuesday   Wednesday   Thursday   Whole Week  

-----===== THURSDAY 2002-07-11 =====-----

Working Group Scattering
------------------------

CE: discussion of the different approaches of the RT equation from the
    mm (ARTS) and vis/UV (STORM model) region for the different parts,
    extinction/scattering/absorption.
    Successive order scattering model in ARTS-1.1 (e.g. loops until
    convergence)
Ute: This loop is sensitive to the evaluation of the phase matrix
     since you loop many times over the phase matrix integral.
CE: STORM and ARTS handle diffuse polarized light
    ARTS handles also rotationally symmetric aspherical particles while
    STORM handles spherical particles.
    STORM uses Fourier decomposition of the phase matrix and intensity
    between azimuth and zenith angles (only possible for spherical particles).
NK: JM has shown that in the mm range the calculation shows that 
    the scattered waves are coherent in the forward-backward
    directions. ARTS assumes incoherence in all directions.
CE: plans:
    - use of Gauss-Loballo quadratures method used for integration
    - check if the convergence of RT equation is also possible for
      larger optical depths.
    - use of Tim Rother (DRL) data base for cloud particles  
Ute: interaction principle in STORM:
     describe the way of the light through the different layers of
     the atmosphere in terms of emission, reflection and
     transmission. This includes already multiple scattering.
     It should also be possible to use this approach for ARTS.
Ute: one should be aware of how the treatment is with contributers to
     ARTS from outside Bremen/Goeteborg. How are contributers treated 
     with respect to publications and ARTS distribution and such
     stuff? How is the policy? 
     
PE: Bremen should create a www page about this workshop results with
    results and links.

PE: we hope for a next workshop next year at Bredbeck.
     
PE : Instead of just discussing the forward models, we can include
     retrieval methods in the future workshop

A brief note on our discussions can be found here(ps format). 
A detailed description of the STORM model is also accessible(ps file). 
The figures can help in understanding the geometry(ps file) and 
integration scheme(ps file).


Working Group Validation and Comparison Model vs. Data
------------------------------------------------------

MK: AMSU-A/B data analysis
    match of ARTS/radiosonde data vs. AMSU-B data
    good agreement for channels 17/18/19/20
    channel 16 agrees with ARTS by using an optimized emissivity
    AMSU-A: ch. 4/5/6 we see a slope in the comparison,
    data is higher in TB than ARTS/radiosonde predict.
    suggestion to do the analysis for another location
    Cabauw (NL) where SC and TH have some measurements done.
VJ: emissivity retrieval for Cabauw (NL) to see the robustness of the 
    retrieved emissivity at Lindenberg.
SC: CLIVANET measurements (part of BALTEX experiment) at Cabauw (NL) 
    Intercomparison with standard abs. models. for 20-90GHz
    differences of up to 2K@30GHz and 7K@90GHz(?) are seen.
    At 90GHz the diff. can not be explained at the moment.
TH: MARSS ground based measurements at Cabauw (NL).
    Additionally airborne based measurements with MARSS were performed
    numerously at different climate conditions (equator to poles).
    H2O foreign continuum were tried to adjust to data of all the
    flights.
    Difficulty is that all the lab. data for cont.fit is >273K which
    leads probably to differences in the low temperatures of polar 
    regions. 
    However, it can not be unambiguously decided from the MARSS data 
    set which component of the continua has to be updated.
TK: presents comparison between the MARSS/POLEX measurements with ARTS.
    Future plans is to compare Atmospheric Radiation Measurement 
    Program (ARM) data with ARTS different water vapor
    absorption models, including the new parameterization of 
    JQSRT, 2002, vol. 74, pp 545-562, 2002. 

   


Working Group SMILES
--------------------

ED: - New limb submm sounder on ISS developed by Japan NASDA/CRL
      which will be launched in 2006.
    - New mission plan end of July 2002 available (ask YK for a copy).
    - Comparison of retrieval simulation results. In general good
      agreement between Moliere, Smiles Simulator and ARTS.
    - Structure of the ground based segment discussed (which
      inst. processes which level in the data processing chain).
    - Baseline retrieval is performed -> will be an additional 
      option for Moliere.



   
Working Group ARTS
------------------

DF: installing is quite easy. Documentation for the user installation 
    and user experiences with ARTS is missing.

action items formulated from this group:
DF: interface to BEAMCAT
OL: easier handling of MSDOS/UNIX line breaks in files
OL: set up ARTS user mailing list
OL: create development platform to allow external developers easier access to
    the ARTS cvs repository
PE: clarify hidden spectral line parameters in arts and make it 
    more transparent (e.g. line broadening for JPL catalog, isotopic ratios).
PE: QPAC running on MS Windows machines

PE confirms that all the ARTS developers from Goeteborg/Bremen will
give as much support as possible for all the ARTS users.  However
ARTS-1-0 development will stop now and ARTS-1-1 is in progress. For
normal users ARTS-1-0 should be sufficient and is more stable than
ARTS-1-1 which is a big project for the next years.


------------
ACTION ITEMS
------------

- all participants can contribute to the workshop home page with 
  additional information either by sending appropriate electronic
  versions of a www link whwich will be included in the workshop home
  page.
- SC will provide all participants with the necessary information to 
  access the home page of the CLIVANET measurement campain at 
  Cabauw (NL).

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