Tutorials

In this section, we offer a set of Tutorials that users can follow to learn using the Atmospheric Look-up Table Generator (ALG) software tool and its generated data. In addition, users can also use these tutorials as examples of possible research applications based on published results. If you would like to add your own tutorial to this Help manual, please don't hesitate to contact us.

Tutorial 1: Basic usage of ALG software tool and its data

In this tutorial, we will learn the basic usage of the ALG software tool, i.e., how to generate a new LUT based on an atmospheric RTM (6SV in this example). We will also show how to extract and analyse the LUT data produced by ALG with basic examples for plotting, constructing top-of-atmosphere (TOA) radiance and atmospheric correction.

This tutorial is aimed for basic users of ALG and for those users who want to review the steps of creating a new atmospheric LUT.

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Tutorial 2: Analysis of aerosol optical properties

Suspended particles (aerosols) are one of the main contributors of light scattering in the atmosphere radiative transfer. Understanding the radiometric effect of aerosol optical properties in top-of-atmosphere (TOA) radiance is therefore necessary to properly compensate for it and improve the quality of atmospheric correction.

In this tutorial, partly based on Vicent et al, 2017, we will learn how to generate atmospheric LUTs with different options for the nodes distribution. These LUTs will be based on the coupling between the OPAC aerosol database and MODTRAN. In addition, we will also show how to extract and analyse the OPAC-related data produced by ALG.

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Tutorial 3: Intercomparison of Atmospheric RTMs

Atmospheric radiative (RT) transfer code comparison studies are carried out to estimate their performance, accuracy and characteristics. These studies are also important in the field of passive remote sensing, where RT codes are used mostly for calculation of look-up tables for satellite data processing algorithms.

In this tutorial, partly based on (Kotchenova et al, 2008), we will illustrate a few differences between individual simulations of MODTRAN and 6SV.

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Tutorial 4: MODTRAN band model and multiple scattering

MODTRAN is a powerful atmospheric RTM that solves the RT equation taking into account the coupled effects of absorption and multiple scattering. However, the MODTRAN execution of the accurate DISORT algorithm, in combination with correlated-k treatements for gaseous absorptions, turns into computationally expensive simulations, hampering the practical usage of MODTRAN into time-effective applications.

In this tutorial we will explore the various options available in MODTRAN to select the method/accuracy for solving the RT equation and treat the gaseous absorptions.

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References