Observed Arctic Cyclone Forcing of Coupled Air-Ice-Ocean Dynamic and Thermodynamic Processes
Abstract
Improved understanding and prediction of Arctic cyclones and their surface impacts are important for supporting increasing human activity in the Arctic Basin. Arctic cyclones may be deep or shallow, may develop within the Arctic or be advected in, and may occur during all seasons. Many are believed to be linked with tropopause polar vortices (TPVs) and, at times, with phasing of existing weak low-level circulations with the TPVs. Arctic cyclones can produce strong dynamic and thermodynamic impacts on the Arctic surface,whether the surface consists of ice, ocean or land, and these impacts are often of importance for human activity. The evolution ofboth cyclones and TPVs is affected by diabatic heating processes associated with clouds, precipitation and boundary-layer mixing, which are also important for cyclone-surface interactions. Most Arctic cyclone studies use numerical models and reanalysis data. Unfortunately, diabatic processes are ones especially problematic in numerical models, contributing to poor predictability of Arctic cyclone evolution and surface impacts. Over the past few years, we have merged historical Arctic observational data during cyclone events with reanalysis products for spatial context, and examined the structure, evolution and surface impacts of Arctic cyclones. Observations used include in-situ and surface-based remote sensing of tropospheric thermodynamic and kinematic features associated withdiabatic heating (e.g., cloud, precipitation, and boundary-layer properties), and surface, sea ice, and upper-ocean measurements ofthermodynamic and kinematic properties and processes. Using observations alleviates uncertainty due to poor model representation of these processes. The original project objectives included: 1) Identify Arctic cyclones in historical observational data sets, merging the observations with reanalyses. Characterize their vertical and spatial structure, mesoscale features, strength, evolution, season, origin, and associated surface conditions. Explain any linkages.2) Examine the dynamic and thermodynamic coupling between Arctic cyclones, and their free-tropospheric and boundary-layer features, with ice and ocean characteristics and processes. The coupling processes may include energy and momentum fluxes and precipitation, while the latter may include ice motion, ice deformation, ocean mixing, and sea state.3) Use an air-ice-ocean coupled mesoscale model to examine key processes related to cyclone-surface interactions, and transfer gained knowledge to DRI participants.Much progress was made on all objectives until administrative failures led to leaving much of this work undocumented and unpublished. The proposed work is primarily to document the completed work by producingmanuscripts on Arctic cyclone interactions with, and impacts on, sea ice. Most of the analysis has been completed, though small amounts of additional analysis will be needed as these manuscripts are developed. Case studies from older field programs and many from the newer MOSAiC field program contain observational analyses of significant air-ice-ocean interaction processes during Arctic cyclone events, and will be the foci of these manuscripts. Key processes linked to Arctic cyclones include surface energy gain/loss (ice melt/freeze) through turbulent and radiative fluxes, upper-ocean mixing, inertial ice motion, and ice divergence. The analyses provide an assessment of cyclone impacts on ice conditions, such as concentration and movement. The observations also provide synopticand mesoscale cyclone evolutionary context to the observed air-ice-ocean interactions, enhancing understanding of the forcing. Thecompletion of these studies will significantly improve our understanding of processes involved in cyclone-induced coupled air-ice-ocean interactions, and provides unique validation opportunities for testing of coupled models through knowledge transfers to other DRI participants and elsewhere.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Sep 11, 2023
- Source ID
- N000142312826
Entities
People
- Ola Persson
Organizations
- Office of Naval Research
- Regents of the University of Colorado
- United States Navy