The GRASP Package. An overview.

Generalized Retrieval of Atmosphere and Surface Properties

Oleg Dubovik

Laboratoire d'Optique Atmosphérique

Fabrice Ducos

Laboratoire d'Optique Atmosphérique

David Fuertes

GRASP SAS

A printable version of this document can be obtained here: docgrasp.pdf

This document describes an overview of the GRASP project, its goals and its architecture. If you want to contribute to the development, you may be more interested in the technical documentation.

The source code of this documentation is in the same repository as GRASP open algorithm. If you want to contribute with your corrections, please check how to do it in User documentation chapter.

Copyright © 2024

01 February 2024

Table of Contents

Foreword
1. Caveat
2. What you will find in this document
3. What you won't find in this document
4. Versioning
1. Introduction
1.1. Scientific background and heritage
1.2. Generalized aspects of GRASP algorithm and package
1.2.1. Generalized approach of numerical inversion
1.2.2. Practical generalization of the algorithm for atmospheric remote sensing
1.2.3. Adaptation of GRASP for general user
1.3. Concept of GRASP software package
2. GRASP software package
2.1. GRASP architecture
2.2. GRASP input and retrieved data
2.2.1. Measurements and retrieved parameters
2.2.2. GRASP inputs
2.2.3. GRASP input data structures
2.2.4. Input text files for running the Scientific Core alone
2.3. GRASP Scientific Core algorithm
2.3.1. Overall structure
2.3.2. Forward model
2.3.3. Numerical Inversion
2.4. GRASP Control Unit
2.4.1. Configuration manager
2.4.2. Controller Module
2.4.3. Abstract input and output drivers
2.4.4. Concrete input and output data drivers
2.4.5. GRASP file organization
2.4.6. External Libraries used by GRASP code
3. Installation
3.1. Introduction
3.2. Hardware requirements
3.3. Operating Systems
3.4. Access to GRASP Open repository
3.5. Building and installing GRASP
3.5.1. Dependencies
3.5.2. Basic installation of GRASP
3.5.3. Advanced compilation
3.6. Running the code
3.6.1. Usage of GRASP: The configuration file
3.7. Code repository and extensions
3.7.1. GRASP Manager
3.8. Known problems
4. How to use GRASP
4.1. How to run the code
4.1.1. Settings file
4.1.2. Retrieved characteristics
4.1.3. Noise simulation
4.2. Input module
4.2.1. The SDATA format
4.2.2. Angle definition
4.2.3. Input information for characteristics
4.2.4. How to prepare the photometer data
4.2.5. How to prepare the lidar data
4.2.6. How to prepare nephelometer data
4.3. Output module
4.3.1. The list of GRASP output parameters
4.3.2. GRASP classic output description
4.4. Forward model
4.4.1. How to use the forward model: Derived products and reprocesing data
4.4.2. Synthetic data
4.5. Aerosol modeling in GRASP
4.5.1. Kernels
4.5.2. Models
4.5.3. Chemistry
4.5.4. Transport models
4.6. Error estimation
Bibliography
Glossary

List of Figures

1.1. Structure of the GRASP software package
1.2. Structure of the GRASP software package
1.3. Structure of the GRASP software package
2.1. The architecture of the GRASP software package
2.2. Illustration of managing input data for GRASP software package.
2.3. General structure of the GRASP scientific algorithm (Fig.3 in Dubovik et al. 2011).
2.4. General organization of Forward modeling in the algorithm
2.5. Organization of GRASP Numerical Inversion: Single-Pixel Scenario
2.6. Organization of GRASP Numerical Inversion: Single-Pixel Scenario
2.7. Organization of GRASP Numerical Inversion: Multi-Pixel Scenario
2.8. Illustration of the data processing by the Controller
2.9. Structure of the utilization of public standard libraries in the GRASP code
3.1. Excerpt of configuration file
4.1. Translation of settings file into initial guess array
4.2. Evolution of retrieved characteristics during GRASP processing
4.3. An example of SDATA file
4.4. Definition of GRASP geometry
4.5. Ground based angles definition example
4.6. Example of a possible use of imagedat
4.7. An example of the residual information in GRASP classic output
4.8. An example of the vector of retrieved parameters in GRASP classic output
4.9. An example of the aerosol volume concentration in GRASP classic output for two aerosol modes
4.10. An example of the Aerosol Optical Depth in GRASP classic output for two aerosol modes
4.11. An example of the fitting information in GRASP classic output for one wavelenght of one pixel with TOD and irradiance measurements

List of Tables

3.1. SPARSE_SOLVER's valid values
3.2. BLAS valid values
3.3. Main CONSTANTS_SET values (installed by default)
3.4. BUILD valid values
3.5. Some common settings
4.1. List of GRASP options
4.2. Available GRASP characteristics
4.3. The SDATA main structure
4.4. The CELL structure
4.5. The PIXEL structure
4.6. Types of measurements
4.7. Specific examples in ground based angle definition example
4.8. Sunphotometer angle description

List of Equations

4.1. Conversion from absolute radiances to normalized, reduced radiances
4.2. Conversion from θgb (ground based) to θG (GRASP)
4.3. Conversion from ϕgb (ground based) to ϕG (GRASP)
4.4. Conversion from θn (nephelometer scattering angle) to θG (GRASP)
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   Foreword