Simulation of realistic EarthCARE spaceborne Doppler products from ARM ground-based and SPIDER airborne data

Simulation of realistic EarthCARE spaceborne Doppler products from ARM ground-based and SPIDER airborne data

O.O. Sy*, S. Tanelli*, N. Takahashi**, Y. Ohno**, H. Horie**, P. Kollias***

*California Institue of Technology, Jet Propulsion Laboratory, Pasadena, USA

** National institute of Information and Communications Technology, Koganei, Japan *** Mc Gill University, Montreal, Canada

ousmane.o.sy@jpl.nasa.gov , simone.tanelli@jpl.nasa.gov

The W-band Cloud-profiling radar (CPR) on ESA and JAXA's future Earth Cloud Aerosol Radiation Explorer (EarthCARE) mission will be the first spaceborne Doppler cloud radar to ever fly [1]. This CPR is expected to provide an unprecedented global coverage of vertical-velocity field distribution in clouds of the Earth's atmosphere, and therewith a better characterization of dynamic energy transfers in the atmosphere.

Prior to EarthCARE's launch, one needs to simulate the Doppler products to be expected from such a CPR, viz. the radar reflectivity and the mean Doppler velocity. Our work addresses this need by applying a detailed simulation scheme to existing ground-based and airborne Doppler measurements to generate realistic EarthCARE-like data.

The input to our algorithm consists of actual atmospheric W-band Doppler measurements obtained either from ground-based radars at ARM facilities [2], or from airborne ones such as the JPL/UMASS Airborne Cloud Radar (ACR) and the NICT SPIDER radar [3].

Several corrections are then applied to account for the spacecraft motion as well as the spaceborne antenna characteristics. The realism of the simulated products is also achieved in terms of spatial and temporal resolution. Further, the effects of random fluctuations, noise and finite temporal sampling are included.

In addition to highlighting the peculiarities of the generation of Doppler products according to the source of the original input data, and the expected performance of CPR in various cloud scenarios, our paper will show corrections that are planned for ground processing the CPR data to recover the mean-Doppler velocity, particularly in the presence of aliasing and non-uniform beam-filling contaminations.

[1] Nakatsuka, H.; Horie, H.; Okada, K.; Sakaide, Y.; Kimura, T.; Ohno, Y.; Sato, K.;

Takahashi, N.; Kumagai, H., "Development status of cloud profiling radar for EarthCARE" Proc. SPIE 7474, 2009.

[2] Widener, K.; Mead, J., "W-Band ARM Cloud Radar Specifications and Design", Fourteenth ARM Science Team Meeting Proceedings, 2004.

[3] Horie, H.; Iguchi, T.; Hanado, H.; Kuroiwa, H.; Okamoto, H., Kumagai, H., "Development of a 95-GHz Airborne Cloud Profiling Radar (SPIDER),"  Technical Aspects IEICE TRANSACTIONS on Communications, vol. E83-B, pp. 2010–2020, 2000.