ECSIM Model and Algorithms Document

The Earth Clouds and Radiation Explorer (EarthCARE) mission is a joint initiative between the European Space Agency (ESA) and two Japanese agencies, namely the Japanese Aerospace exploration Agency (JAXA) and the Japanese National Institute of Communications Technology (NICT). EarthCARE is a unique remote sensing platform aimed at improving our understanding of the interaction between Clouds and Solar and Thermal radiation within the Earths atmosphere. The EarthCARE platform will carry a combination of active (cloud radar and lidar) and passive instruments for cloud/aerosol and radiation remote sensing.
In order to develop retrieval algorithms and in order to investigate various instrumental tradeoff issues it is necessary to simulate the mission. In order to be useful the simulations of the different instruments must be consistent with each other. As well, it is desirable to be able to consider cases ranging from idealized ‘simple’ scenes to complex realistic scenes based on the output of cloud-resolving models. The EarthCARE simulator (ECSIM) represents a unified approach to simulating the mission which satisfies these requirements. This document is intended to provide an overview of ECSIM focusing on the underlying architecture and the theory behind the various scientific model components of ECSIM. Material presented in the remainder of this section describes the history, the underlying philosophy behind the package as well as the basic structure. Details of the theory behind each model as well as example results and implementation details are given in Sections 2–5. Auxiliary tools and routines are described in the appendices.