Development Status of Cloud Profiling Radar for EarthCARE
- Paper number
IAC-08.B1.3.10
- Author
Mr. Hirotaka NAKATSUKA, Japan Aerospace Exploration Agency (JAXA), Japan
- Year
2008
- Abstract
Global three-dimensional cloud distributions and their properties are important information to estimate the earth radiation budget more precisely. The interactions between cloud particles and aerosols are also focused to improve accuracies of climate model. In order to meet expectations of scientists developing climate models for global warming problem, European and Japanese space agencies plan to launch a satellite called EarthCARE (Earth Clouds, Aerosols and Radiation Explorer). A Cloud Profiling Radar (CPR) is installed on this satellite as a main sensor to observe clouds. Comparing with optical sensors, millimeter wave radar can penetrate upper thick clouds and observe cloud or rain layers below it. In this paper, design and development status of EarthCARE CPR areintroduced. EarthCARE mission, proposed by European and Japanese scientists, has been selected for implementation as sixth Earth Explorer Mission of European Space Agency’s (ESA) Living Planet Program. The mission focuses on clouds and aerosols effect on the earth radiation flux budget. For this purpose, vertical structure of clouds and aerosols are important as well as horizontal distributions of clouds on global. ESA will develop three sensors and satellite and Japan (JAXA and NICT) will develop CPR. EarthCARE CPR is millimeter-wave radar which has high sensitivity. Radar frequency is the same as CloudSat CPR (94GHz), but radar sensitivity is about ten times better because of the lower orbit and larger antenna size. Minimum radar reflectivity of EarthCARE CPR is -35 dBZ at TOA in condition of 10 km integration. The transmit pulse width is 3.3 micro seconds, which is the same as CloudSat. Sampling intervals 100 m, which is 250 m in CloudSat. Vertical range of observation will be 20, 16, 12 km depending on the latitude. Minimizing observation window is necessary to achieve higher pulse repetition frequency (PRF) for accurate Doppler measurement. Then variable PRF, which is adapted with satellite height change in latitude, is adopted. Footprint size of CPR is about 700 m at ground. In order to obtain good SNR and reduce data size, horizontally averaged data with along track of 500 m is minimum pixel size. This year, EarthCARE CPR project has been reviewed by Japan side. After passing several reviews, Experimental Model production of CPR will start this year. Because of tight schedule, several critical components are developing ahead. In order to get better sensitivity and better Doppler accuracy, detail designs of the CPR is being studied now.
- Abstract document
- Manuscript document
(absent)