Rain observations from a Micro rain radar MRR-PRO deployed on R/V Maria S. Merian during EUREC4A campaign

In the field campaign !Elucidating the Role of Clouds-Circulation Coupling in Climate” better known as EUREC4A (January 2020-February 2020), a K band (around 24 GHz) micro rain radar from Metek GmbH (Peters et al., 2002) was deployed on the R/V Maria S. Merian to collect observations of attenuated reflectivity, fall speed of drops, rain rate, and liquid water content of profiles containing rain in zenith pointing mode. The zenith radar measurements were taken in the Atlantic Ocean south-east of Barbados between 19 January 2020 and 19 February 2020. Typical time resolution is 1s, while vertical resolution is 10 m up to 1290 m, the maximum observation height. Only in the initial days of the campaign, observations were taken with 10 s or 5 s resolution and maximum range at 650 m. Data from these days have been resampled to the previously defined mode.<br />
Data are provided in NetCDF format and enhanced for CF compatibility and are accessible online via the eurec4a intake catalog.<br />
The MRR-PRO was installed on the active stabilization table from the US-Atmospheric Radiation Measurement program mobile facility 2 (ARM-AMF2) to reduce the impact of ship motions on the Doppler zenith pointing observations (Coulter et al., 2016). The MRR-PRO radar data with time resolution of 1s were post-processed as follows. An algorithm for correcting for ship motions was applied to the Doppler spectrum to shift it accordingly to the correction to be applied and afterwards the data were post-processed in multiple steps. Data with 5 or 10 seconds time resolution were simply post-processed without application of ship motion correction because the typical period of the ocean waves is less than the time resolution. The entire correction algorithm and the multiple post-processing steps applied are described in a data publication (Acquistapace et al., 2021) to be submitted to Earth System Science Data (ESSD). For correcting in the intervals of time in which the stable table did not work (approximately 35% of the total measurement time), horizontal wind speed and direction from the output of dedicated ICON simulations over the EUREC4A domain were used. The model runs have 1.25 km spatial resolution and hourly time resolution. Simulations are initialized and nudged on the lateral boundaries by the operational analysis of the atmospheric state by the European Centre for Medium Range Weather Forecasts (ECMWF). The simulation setup follows Klocke et al. 2017.