Understanding the role of the stratosphere in subseasonal to seasonal variability and predictability of Arctic weather systems
Abstract
Increased skill in subseasonal–to–seasonal (S2S) forecasts is linked to resolving atmospheric modes of variability that evolve on timescales longer than the medium range yet shorter than the inter-seasonal timescale. A subset of these modes of variability occurs in the stratosphere, where the slowly evolving atmosphere provides a memory of the initial state as the top boundary conditions in numerical model. Motivated by the stratospheric source of predictability at S2S timescales and the known gap in understanding of the drivers of S2S variability in Arctic weather systems, the proposed research examines this stratospheric source of predictability in response to the DRI on Overcoming the Barrier to Extended Range Prediction over the Arctic. The proposed research examines the role of the stratosphere in S2S variability in the Arctic region by considering two types of stratospheric variability from two different perspectives. The proposed research will examine stratospheric variability in terms of dynamic extremes (weak and strong vortex events) as well as ozone-radiative variability. The analysis will consist of two parts: (1) A climatological and composite perspective that will primarily utilize the NASA Modern-Era Retrospective Analysis for Research and Applications Version 2 (MERRA- 2) reanalysis dataset; and (2) A reforecast and idealized modeling perspective using the WWRP/WCRP S2S Prediction Project operational model reforecast database as well as data from the Navy NAVGEM and NCAR’s Whole Atmosphere Community Climate Model, Version 4 (WACCM4). The importance of cyclones in the sea ice variability and socio-economic development in the Arctic region serve as an impetus for the analysis to focus on the S2S variability of Arctic cyclone precursors [i.e., tropopause polar vortices (TPVs)]. Since the TPV structure is vertically centered on the tropopause, it is a reasonable to hypothesize that TPVs are influenced by the variability in the state of the stratosphere, such that the anomalous stratospheric conditions may manifest themselves in the variability of TPVs and TPV induced cyclogenesis events. The proposed project will investigate the S2S variability of TPVs and their associated properties [i.e., frequency, distribution, amplitude, size, and attendant features (i.e., jet-front systems and surface cyclones)] in relation to the dynamic and radiative states of the stratosphere. The main objective of the project will be to answer the following key research question: Does a TPV-stratosphere coupling relationship exist during the Arctic summer, winter, and/or transition seasons? It is anticipated that the proposed research will contribute to answering the following key research questions from scientific issues section of the DRI: • Can multi-scale modeling systems be used to bridge the climate/weather domain inhabited by Arctic cyclones and TPVs and increase predictability of this seasonal driver of smaller scale forcing events? • What factors influence the predictability of Arctic cyclones and what are the most important parameters and observations required for skillful forecasts of high-latitude cyclones and smaller-scale polar lows? • What processes contribute to the intensification, properties, precipitation, and evolution of Arctic cyclones and their interactions with clouds and the boundary layer?
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Mar 26, 2018
- Source ID
- N000141812199
Entities
People
- Andrea Lang
Organizations
- Office of Naval Research
- Research Foundation for the State University of New York
- United States Navy