Project Overview

FATIMA Ice-Fog Project Summary

This proposal requests funding for escalation of the third and final field campaign of the Fog and turbulence interactions in marine atmosphere (Fatima) MURI project of the US Office of Naval Research. Since Fatima was first funded in 1991, many collaborators from national and international academic institutions and research laboratories have joined the project with alternative funding support. The first two Fatima field campaigns on marine [liquid droplet] fog conducted in Grand Banks (northern Atlantic Ocean) and Yellow Sea (off the South Korean coast) were a resounding success. The third Ice Fog Campaign (Fatima-IF), which is the focus herein, is also slated to be much more expansive than what was originally anticipated with additional participants. Ice Fog (IF) is defined as a condition in the lower atmospheric boundary layer where the visibility drops below 1 km due to deposition of water vapor from the environment on ice nuclei or by freezing of small supercooled droplets. IF is also associated with mixed phase stratiform clouds carrying supercooled droplets and ice crystals characterized by low-level inversions. IF possibly is the least understood type of fog, given the measurement and logistical difficulties of working in harsh frigid environments and intricacies of physicochemical processes involved in IF environs. Nonetheless, IF has conventional applications in high-latitude navigation (e.g., in the new Arctic) and electromagnetic communications as well as in emerging arenas of directed energy and hypersonic flight. Fatima-IF is designed to better understand IF processes, in particular the role of turbulence in its formation, maturation and dissipation (i.e., lifecycle) in a field campaign to be conducted at the North Slopes of Alaska (NSA) User Facility of the Atmospheric Radiation Measurement (ARM) Program of the US Department of Energy. A comprehensive array of high-end instrumentation available at NSA with infrastructure support provided by ARM User Facility, augmented by guest-provided [novel] instrumentation, offer unique opportunities for Fatima-IF to collect an unprecedent variety of data and delve into IF processes. Permission to use NSA ARM User Facility has been requested in a separate formal proposal to ARM Program. The Fatima-IF intends to study (i) nucleation and ice crystal formation during IF events in the presence of low boundary-layer clouds, and the role of turbulence thereof, (ii) how air-sea fluxes impact coastal ice-fog formation, (iii) microphysical parameterizations for IF, including the efficacy of existing parameterizations, and (iv) vertical profiles of IF microphysical properties, which are essentially unavailable hitherto, in the context of formation and dissipation mechanisms of IF and for improving Numerical Weather Prediction (NWP) models. Several hypotheses related to the roles of inversion layer, surface turbulence, cloud-top convection and bio-chemo-physical properties of aerosols have been proposed and will be tested.

The campaign will take place during 15 November to 6 December, 2025 where Fatima-MURI institutions (University of Notre Dame, Naval Postgraduate School, University of Utah and Scripps Institution of Oceanography) and Collaborators will be deploying cutting-edge Guest Instruments. Their collaboration with the Naval Research Laboratory is expected to provide NWP simulations and climatological forecasting for guiding the campaign. As were in two previous campaigns, Fatima-IF group will conduct high resolution large-eddy simulations in support of data analysis and interpretation. Quality controlled/assured data will be deposited and made available in the ARM User Facility and Fatima data bases for the benefit of scientific community at-large.