EarthCARE science mission objectives

Clouds and aerosols are known to play crucial roles in the climate system; however, they are also main sources of uncertainty in our knowledge, and especially large efforts are needed to evaluate their interactions (IPCC 2007). The Japan Aerospace Exploration Agency (JAXA) is carrying out the EarthCARE (Earth Clouds, Aerosols, and Radiation Explorer) mission in cooperation with the European Space Agency (ESA) under ESA's Earth Explorer Program. The primary objective of the EarthCARE mission is to improve our understanding of the roles of clouds and aerosols and their interaction in the context of the Earth's radiation budget and climate in order that they may be represented well in regional and global climate models and in numerical weather prediction models. Currently, JAXA expects the EarthCARE data to be used to improve cloud formation processes in cloud system resolving models and radiative characteristic models of aerosols and clouds. Then, the improved models can be used to analyze the EarthCARE data and reduce the inconsistency between satellite-observed data and calculated results through the assimilation process. We have several numerical models in Japan to simulate aerosol and cloud fields on various scales from meso to global. For example, the MIROC coupled atmosphere-ocean General Circulation Model (GCM) developed by the University of Tokyo and the NIES (National Institute for Environmental Studies) will be useful in evaluating climate sensitivity and the interaction of aerosols and clouds with climate systems. The NICAM cloud system resolving model developed by JAMSTEC (Japan Agency for Marine-Earth Science and Technology) and the University of Tokyo cloud system resolving model can simulate the global cloud system with a spatial scale of several kilometers without cumulus parameterization, which produces a large uncertainty in the GCM models. To achieve the purposes written above, JAXA and the National Institute of Information and Communications Technology (NICT) are in charge of the Cloud Profiling Radar (CPR) and ESA is in charge of the Atmospheric Lidar (ATLID), Multi-spectral Imager (MSI), and Broadband Radiometer (BBR). The three agencies will work collectively. This is one more advantageous point over the A-train mission. Furthermore, the CPR was designed with the capability of measuring vertical profiles of Doppler velocity. This measurement will be the first attempt to obtain Doppler Velocity from space. This paper describes the scientific strategy and plans for each activity in Japan.