The Marine Fog Microphysics Based on the Ship Data during FATIMA-I and II

The objective of this work is to evaluate marine fo microphysical measurements obtained by the instruments located on the research vessels called Canadian Atlantic Condor and Korean Onnuri. Various fog measurement devices such as FM120, CDP, and BCP (DMT Inc), OPC-N3 (Alphasense) and FD70 (Vaisala) were used to understand marine fog microphysics and life cycle properties during the Fog And turbulence Interactions in the Marine Atmosphere) FATIMA-I and II field campaigns. Measurements were collected during (i) July 2022, as a part of the FATIMA-I field campaign that took place on Sable Island and the Grand Banks (GB) of northeastern Canada and (ii) 20 June to 09 July 2023 during the FATIMA-II field campaign that took place in the eastern Yellow Sea (YS). The measurements were gathered by a Gondola (CDP and BCP) and FM120 on the deck and a CDP mounted on a crane of the R/V Atlantic Condor and R/V Annuri, and by FM120 and OPCs, as well as the 3 instrumented turbulence towers located in the Sable Island that included a UAV based OPC measurements. During YS campaign, in addition to Onnuri measurements, three ocean observing sites with meteorological towers and visibility sensors were involved in data collection. Korean Met Institute (KMI) also provided observations for atmospheric profiling and microphysics for some IOPs.

Horizontal wind speed (Uh), wind direction, and the ship heading are considered in the analysis. The FD70p measurements were used in the discrimination of precipitation and drizzle conditions. The OPC-N3 had 24 bins from 0.3 µm to 40 µm while the FM120 and CDP had 30 bins from 1-50 microns, and the BCP had30 bins from 5-75 µm size range. Turbulence fluctuations obtained from 3D sonic anemometers were used to study variability in the particle size distribution, which was considered in the calculations. Marine fog microphysics characteristics, as well as synoptic conditions over the GB and YS are found to be significantly different. In the analysis, various parameters such as the liquid water content (LWC), droplet number concentration (Nd), and mean volume diameter (MVD) are used to develop microphysical parameterizations and evaluate the variability. In the presentation, the visibility values calculated from the PSDs and visibility sensors will be evaluated, and its possible impact on marine fog predictions and physical parameterizations for GB and YS will be discussed with respect to synoptic weather conditions.

This work was funded by the Grant N00014-21-1-2296 (Fatima Multidisciplinary University Research Initiative) of the Office of Naval Research, administered by the Marine Meteorology and Space Program.