DOI: 10.5443/10906
title: Structure and evolution of the polar stratosphere and mesosphere and links to the troposphere during the International Polar Year, 2007-2009 (SPARC IPY)

description: There are six individual sets of model results in this dataset. Some details are listed below (full lists of modelled variables are provided in the accompanying README file). 1. ECMWF (European Centre for Medium-range Weather Forecasts): Native format: GRIB; Horizontal grid: 1440 longitudes x 721 latitudes (.25 x .25 degree grid); Vertical grid: 91 hybrid model levels to 0.01 hPa; 7 modelled variables; Dates available: 01 June 2007 to 31 May 2009. 2. NCEP (National Centers for Environmental Prediction): Native Format: GRIB; Horizontal grid: 1152 longitudes x 576 latitudes (~0.313 x 0.313 degrees); Vertical grid: 64 model levels to ~0.2 hPa; 10 modelled variables; Dates available: 01 April 2007 to 14 June 2009. 3. UKMO (United Kingdom Meteorological Office): Native Format: NetCDF once per day (both regular and UARS); Horizontal grid: 640 longitudes x 480 latitudes (0.5625 x 0.375 degrees)/UARS: 96 longitudes x 73 latitudes (3.75 x 2.5 degrees); Vertical grid: 30 pressure levels to 0.1 mbar/UARS: 25 levels to 0.1 mbar; 5 modelled variables; Dates available: 01 April 2007 to 31 March 2009. 4. GMAO (Global Modeling and Assimilation Office, NASA): Native Format: HDF; Horizontal grid: 540 longitudes x 361 latitudes (0.6667 x 0.5 degrees); Vertical grid: 72 model layers to 0.01 hPa; 15 modelled variables; Dates available: 01 June 2007 to 31 May 2009. 5. CMAM-FDAM (Canadian Middle Atmosphere Model - Facility for Data Assimilation and Modelling): Native Format: NetCDF/CCCma; Horizontal grid: 97 longitudes x 48 latitudes (~3.75 x 3.75 degree Gaussian grid); Vertical grid: 71 model levels to ~0.082 hPa; 27 modelled variables; Dates available: 01 November 2005 to 31 December 2009. 6. GEM-BACH (Global Environmental Multi-scale coupled with Belgium Atmospheric CHemistry): Native Format: NetCDF; Horizontal grid: 240 longitudes x 120 latitudes (1.5 x 1.5 degrees); Vertical grid: 80 model levels to ~0.125 hPa; 20 modelled variables; Dates available: 01 March 2007 to 28 February 2009.
description: Purpose: The goal of SPARC IPY is to document the dynamics, chemistry and microphysical processes within the polar vortices during IPY, with a focus on stratosphere-troposphere and stratosphere-mesosphere coupling. A key outcome will be a collection of analysis products from several operational centres and several research centres, which will be archived at the Polar Data Catalogue and the SPARC Data Center. The analysis products will represent the best available self-consistent approximations to the state of the atmosphere during this period. SPARC IPY is linked with several International IPY activities: POLARCAT (Activity 32, which has been endorsed by SPARC), ORACLE-O3 (Activity 99), PANSY (Activity 9), and IASOA (Activity 196). The Canadian SPARC model outputs were shared with IPY-TAWEPI (CCIN#11399). The evolution of stratospheric ozone and other important and related atmospheric constituents in polar regions is tightly coupled to a wide range of processes acting within and outside the winter polar vortices and through the entire atmosphere from the surface to the mesopause. Much of the current understanding of these processes has been achieved within the programme of SPARC (Stratospheric Processes And their Role in Climate), a WCRP (World Climate Research Programme) core project, and other international projects with which it maintains collaborative links. IPY offers a unique opportunity for SPARC to assemble a range of scientific expertise to study the Antarctic and Arctic polar vortices, the loci of key chemical and physical processes associated with ozone depletion and its eventual recovery, as well as of key features of the dynamical coupling between the troposphere, stratosphere, and mesosphere in polar and sub-polar regions. The central goal of SPARC IPY is to document as completely as possible the dynamics and chemistry of the polar vortices and physical properties relevant to processes such as the formation of polar stratospheric clouds. To achieve this detailed picture and yield a unique synthesis of data on the polar middle atmosphere, SPARC IPY will facilitate analysis of available research and operational satellite data, as well as ground-based and aircraft data, and encourage work on data assimilation and inter-comparison of assimilated data sets.
description: Summary: This component of the SPARC IPY activity will be comprised of a data assimilation, modelling and analysis component, which will focus on assimilation and analysis of these observations to yield a comprehensive picture of the observed atmospheric circulation and facilitate prediction of changes in the circulation and associated physical and chemical responses. In addition, this component will include archiving of assimilation products (analyses and forecasts) arising from participating middle atmosphere assimilation groups during the IPY period (2007-2009). Such products will be routinely produced at weather forecast centres using models with vertical domains that extend above the stratopause. Research groups employing chemistry transport models or chemistry climate models will also participate. These analyses are critical for understanding the structure and evolution of the polar vortices, the formation of polar stratospheric clouds, the depletion of ozone, and the initiation of anomalous weather regimes associated with the Arctic Oscillation, and will provide a detailed, best estimate of the state of the atmosphere over the IPY period. It is anticipated that the data will be used in subsequent years as the field campaigns generated by the related IPY activities are analysed in order to provide context for individual measurements.