VLIDORT User's Guide

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8. (Version 2.6). The BRDF supplement has been upgraded to include a facility forgenerating surface glitter BRDFs to include multiple reflections from wave facets.9. (Version 2.6). There is a new “surface-leaving” capability (e.g. for ocean water-leavingor fluorescence applications), and VLIDORT can ingest the correct functions formodeling this physical effect in the RTE. This additional “VSLEAVE” supplementprovides these functions.10. (Version 2.6). Single-scatter calculations are now optional; the model can ingest singlescatter fields from external sources.11. (Version 2.6). An observational geometry facility has been added to improvecomputational efficiency when doing satellite applications. The facility wasincorporated into VLIDORT’s main code as well as the BRDF and VSLEAVEsupplements.1.3. LIDORT-RRS, 2-stream, Linearized Mie/Tmatrix codesThe LIDORT linearization techniques have been applied to the CAO_DISORT coupledatmospheric-ocean code, and it is now possible to generate weighting function with respect tomarine constituents such as chlorophyll concentration and CDOM [Spurr, et al., 2007]. This hasopened the way for a new approach to simultaneous retrieval of atmospheric and ocean quantitiesfrom MODIS and related instruments. [Li et al., 2007].In 2002, a version of LIDORT with inelastic rotational Raman scattering (RRS) was developedfrom first principles, using an analytic solution of the discrete ordinate field in the presence ofadditional source terms due to RRS. This work was written up in [Spurr et al., 2008], andincludes Versions 1.5 through 2.1. The latter code has been used in a number of applicationsinvolving ozone profile and column retrievals from instruments such as GOME and OMI. In2009, a major new development for the LRRS code was the complete linearization of the entiremodel for profile, column and surface Jacobians. A separate User’s Guide is available forLIDORT-RRS.A dedicated 2-stream version of the multiple-scattering LIDORT code was written in 2010, foruse in low-stream interpolation and performance enhancement in hyperspectral retrievalapplications involving many radiative transfer techniques [Spurr and Natraj, 2011]. This 2S codeis entirely analytical, avoiding the use of LAPACK or other numerical schemes.More recently, some new work on the linearization of the T-matrix electromagnetic scatteringtheory has been published [Spurr et al., 2012] in connection with the development of VLIDORTbasedpackages to retrieve aerosol microphysical properties. This work also includes a linearizedMie code formulation.1.4. Scope of documentA theoretical description of the model is given in chapters 2 and 3. Chapter 2 contains severalsections summarizing the essential mathematics and the solution methods of the discrete ordinatemultiple scattering radiative transfer formalism in a multi-layer medium. Some of the discreteordinate theory may be found in the literature, and many more details are found in the papers byR. Spurr. The linearization process and the derivation of Jacobians for atmospheric and surfacequantities are described in some detail, and there are treatments of exact single-scatter12
corrections, and sphericity corrections for the incoming solar beam and the outgoing line-ofsight.In Chapter 3, we go over the derivation of Inherent Optical Property (IOP) input preparation. Thederivation of the standard set of optical properties required for the computation of the Stokes 4-vector field is outlined, and derivations of linearized optical property inputs for the generation ofatmospheric Jacobians are discussed. Also in Chapter 3, we discuss benchmarking the modelagainst literature datasets, and there is another section on the use of performance enhancements,including the “solution-saving” and “BVP-telescoping” options; these are labor-saving devicesdesigned to eliminate unnecessary computation. We also review the Fourier convergence aspectspertaining to the exact treatments of single scattering and direct beam contributions, and the useof a multiple-SZA facility for look-up table generation.Chapter 4 describes the specifics of the VLIDORT 2.6 package. In section 4.1, we give anoverview of the package; section 4.2 has a description VLIDORT’s source code modules. Insection 4.3, we discuss the input configuration file, “makefile” production of executables, andinstallation of the code. In this regard, a number of tests have been written for this release of thecode, and proper installation of the package will result in the confirmation of the test data set thataccompanies the release. In section 4.4, we summarize the important new software standardsadopted for the code and describe exception handling. This version of VLIDORT is in the publicdomain; copyright and licensing issues are discussed in section 4.5. Chapter 4 concludes withsome acknowledgements in section 4.6. Chapter 5 contains references cited in the guide.Appendices for VLIDORT may be found in Chapter 6. Section 6.1 has important tablesdescribing VLIDORT input and output Fortran 90 type structure variables (both basic andlinearized) along with tables illuminating the association between these variables and the filereadinput strings found in VLIDORT’s input configuration file. Section 6.2 discusses theenvironment programs which serve as package installations tests as well as provide the user withexamples of how to incorporate VLIDORT into his or her desired applications. Lastly, section6.3 gives a complete description of the vector BRDF supplement: information on how theBRDFs are constructed, the inputs and outputs of the supplement software, and descriptions ofthe water and land surface BRDFs included in the package.13
Page 1: User’s GuideVLIDORTVersion 2.6Rob
Page 5 and 6: Table of Contents1H1. Introduction
Page 7 and 8: 1. Introduction to VLIDORT1.1. Hist
Page 9 and 10: Table 1.1 Major features of LIDORT
Page 11: In 2006, R. Spurr was invited to co
Page 16 and 17: Matrix Π relates scattering and in
Page 18 and 19: m⎛ P⎞l( μ)0 0 0⎜⎟mmm ⎜ 0
Page 20 and 21: In the following sections, we suppr
Page 22 and 23: of the single scatter albedo ω and
Page 24 and 25: Here T n−1 is the solar beam tran
Page 26 and 27: ~ + ~ ~ (1)~ ~ + ~ ~ (2)~ ~ − ~ 1
Page 28 and 29: The solution proceeds first by the
Page 30 and 31: Linearizations. Derivatives of all
Page 32 and 33: For the plane-parallel case, we hav
Page 34 and 35: One of the features of the above ou
Page 36 and 37: L↑↑ ↑k (cot n −cotn −1)[
Page 38 and 39: Note the use of the profile-column
Page 40 and 41: βl,aer(1)(2)fz1e1βl+ ( 1−f ) z2
Page 42 and 43: For BRDF input, it is necessary for
Page 44 and 45: streams were used in the half space
Page 46 and 47: anded tri-diagonal matrix A contain
Page 48 and 49: in place to aid with the LU-decompo
Page 50 and 51: In earlier versions of LIDORT and V
Page 53 and 54: 4. The VLIDORT 2.6 package4.1. Over
Page 55 and 56: (discrete ordinates), so that dimen
Page 57 and 58: Table 4.2 Summary of VLIDORT I/O Ty
Page 59 and 60: Table 4.3. Module files in VLIDORT
Page 61 and 62: Finally, modules vlidort_ls_correct
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end program main_VLIDORT4.3.2. Conf
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$(VLID_DEF_PATH)/vlidort_sup_brdf_d
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Finally, the command to build the d
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Here, “s” indicates you want to
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The main difference between “vlid
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to both VLIDORT and the given VSLEA
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STATUS_INPUTREAD is equal to 4 (VLI
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5. ReferencesAnderson, E., Z. Bai,
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Mishchenko, M.I., and L.D. Travis,
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Stamnes K., S-C. Tsay, W. Wiscombe,
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Table A2: Type Structure VLIDORT_Fi
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DO_WRITE_FOURIER Logical (I) Flag f
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USER_LEVELS (o) Real*8 (IO) Array o
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angle s, Stokes parameter S, and di
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DO_SLEAVE_WFS Logical (IO) Flag for
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6.1.1.8. VLIDORT linearized outputs
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NFINELAYERS Integer Number of fine
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6.1.2.4. VLIDORT linearized modifie
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The output file contains (for all 3
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The first call is the baseline calc
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for a 2-parameter Gamma-function si
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Remark. In VLIDORT, the BRDF is a 4
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6.3.3.1. Input and output type stru
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Table C: Type Structure VBRDF_LinSu
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Special note regarding Cox-Munk typ
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squared parameter, so that Jacobian
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6.4. SLEAVE SupplementHere, the sur
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is possible to define Jacobians wit
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etween 0 and 90 degrees.N_USER_OBSG
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6.4.4.2 SLEAVE configuration file c
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