Setup for SCORE-MIP radiative transfer model intercomparison

Download pdf

See results

• for 5 different aerosol scenarios:
  1. Low aerosol loading (AOD ~ 0.05); no cirrus cloud: use gas + Rayleigh + aerosol (low_aod)
  2. Low aerosol loading (AOD ~ 0.05) with cirrus cloud: use gas + Rayleigh + aerosol (low_aod) + cirrus
  3. High aerosol loading (AOD ~ 0.3) no cirrus cloud: use gas + Rayleigh + aerosol (high_aod)
  4. High aerosol loading (AOD ~ 0.3) with cirrus cloud: use gas + Rayleigh + aerosol (high_aod) + cirrus
  5. No aerosol (pure Rayleigh): use gas + Rayleigh
• Geometry
  1. Solar zenith angle: SZA = 10, 45, 70
  2. Viewing angle: nadir and sunglint
• Surface
  1. Lambert albedo (same in each band): 0.05, 0.1, 0.3
  2. Ocean sunglint: windspeed 5 m/s with viewing zenith angle = solar zenith angle

• For each layer of a 60 layer atmosphere:
  1. Optical depth of gaseous absorption, aerosol, cirrus and Rayleigh extinction
  2. Single scattering albedo of aerosols and cirrus
  3. Scattering matrix for aerosols, cirrus and Rayleigh (layer independent)
• Spectral range:
  1. Band 1: O2 A-band:
     1. Window w1: 13080 – 13090 cm-1 (1000 spectral points)
     2. Window w2: 12976 – 12980 cm-1 (400 spectral points)
  2. Band 2: 1.61 micron CO2:
     1. Window w1: 6202 – 6206 cm-1 (400 spectral points)
  3. Band 3: 2.04 micron CO2:
     1. Window w1: 4841-4845 cm-1 (400 spectral points)
     2. Window w2: 4815–4819 cm-1 (400 spectral points)

• The RT calculations for each scenario will be carried out for 4 setups of the RT code:
  1. 'scalar accurate': scalar RT with standardized setups
  2. 'scalar fast': fast version of scalar RT code
  3. 'vector accurate': vector RT with standardized setups
  4. 'vector fast': fast version of vector RT code
• Parameters for ‘accurate’ setup: 32 full streams, delta-M on, single scattering correction on, plane parallel, 60 vertical layers
• ‘Fast’ setup: here the code should be run in a configuration so that the RT calculations are sufficiently fast for the retrieval of a large number of spectra
• Groups can also provide the RT calculations only for some of the 4 setups.

All combinations of parameters result in a very large set of spectra to be compared. As a first step we evaluate only SZA=45°, albedo=0.1 or BPDF, band 1 (window 1) and band 3 (window 2).

This results in the following 20 test cases:

Please download the input data: data.zip.

• The data directory contains subdirectories for aerosol, cirrus, gas and Rayleigh that contain files with the optical depth, single scattering abedo and scatteringmatrix
• Optical depth for is given for each spectral point and each vertical layer. The uppermost layer and the last column is the optical depth of the bottom layer.
• Single scattering albedo (ssa) for aerosol and cirrus is given for each spectral point
• The input files are given for each spectral band separately. They will be identified with b1, b2, b3 for the O2 A Band, the 1.6 micron Band and the 2.03 micron band followed by the window number (w1 or w2).
• We assume that the scattering matrix is constant across each band, ie. only one scattering matrix is given per band. The scatteringmatrix file contains all 3 bands
• Scattering matrix is given as alpha1-4,beta1-2 according to following representation (Note that alpha1 is the scalar phase function):
• Rayleigh depolarization factor 0.0279
• Please note that the forward peak of cirrus phase function has been truncated and the other optical properties of cirrus (single scattering albedo) have been modified accordingly.

• Give output as 2 column ASCII files with wavenumber and I or I-Q
• Generate separate file for each geophysical scenario
• Include header that provides information about the run (RT setup, code version etc).
• Start header lines with #
• Provide the computation time for each scenario together with the computation time for the test programme (tespol.f90)