EUREC<sup>4</sup>A's Maria S. Merian ship-based cloud and micro rain radar observations of clouds and precipitation

Abstract

Abstract. As part of the EUREC4A field campaign, the research vessel Maria S. Merian probed an oceanic region between 6° N and 13.8° N and 51° W to 60° W for approximately 32 days. Trade wind cumulus clouds were sampled in the trade-wind alley region east of Barbados as well as in the transition region between the trades and the intertropical convergence zone, where the ship crossed some mesoscale oceanic eddies. We collected continuous observations of cloud and precipitation profiles at unprecedented vertical resolution (7–10 m in the first 3000 m) and high temporal resolution (1–3 s) using a W-band radar and micro-rain radar (MRR-PRO), installed on an active stabilization platform to reduce the impact of ship motions on the observations. The paper describes the ship motion correction algorithm applied to the Doppler observations to extract corrected hydrometeors vertical velocities and the algorithm created to filter interference patterns in the MRR-PRO observations. Radar reflectivity, mean Doppler velocity, spectral width and skewness for W-band and attenuated reflectivity, mean Doppler velocity and rain rate for MRR-PRO are shown for a case study to demonstrate the potential of the high resolution adopted. As non-standard analysis, we also retrieved and provided liquid water path (LWP) from the 89 GHz passive channel available on the W-band radar system. All datasets and hourly and daily quicklooks are publically available. Data can be accessed and basic variables can be plotted online via the intake catalog of the online book "How to EUREC4A".

Fast Atmospheric Response to a Cold Oceanic Mesoscale Patch in the North‐Western Tropical Atlantic

“…For this reason, we derived hydrometeor fraction profiles and Contour Frequency by Altitude Diagrams (CFADs) for radar reflectivity and mean Doppler velocity for non‐rainy cloud columns only. The LWP observations in rainy condition can be biased due to the wet radome of the radar, but we retain the LWP observations also in rainy conditions because all values are much smaller than 1,000 g m −2 , considered as a threshold corresponding to saturation in the MWR channels (Acquistapace, Coulter, et al., 2022). Over the cold SST, the hydrometeor profile displays two main cloudy peaks, one at the LCL, around 700 m, and the second one right below the inversion height (Figure 10b).…”

“…Acquistapace, Coulter, et al. (2022) report a detailed description of the impact of the stabilization on the data, the setup used on the ship, and the details on the retrieval for the liquid water path (LWP). Time series of reflectivity, mean Doppler velocity and LWP are shown in Figures 2c–2e.…”