Stratospheric Processes and their Role in Climate

Project Description
Short Title: SPARC
Project URL:
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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 region 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 core project, and other international projects
with which it maintains collaborative links. The IPY programme 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 the SPARC IPY
programme (hereinafter referred to as 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. This will include data from new measurement
systems as well as from enhanced measurement programmes with
established systems. To complement results provided by new measurement
programmes, weather services carrying out routine radiosonde and
ozonesonde measurements will be encouraged to increase the frequency
of the observations and to store the data with full resolution. As the
lead organization, the SPARC Project will coordinate the SPARC-IPY
programme, promote specific new initiatives and organize workshops and
meetings to facilitate research and dissemination of results. These
efforts will be carried out in the context of the SPARC Project core
thematic programmes of Stratospheric Chemistry and Climate;
Stratosphere-Troposphere Dynamical Coupling; and Detection,
Attribution, and Prediction of Stratospheric Change. SPARC-IPY is the
lead EoI for sub-cluster 7.1 (IPY SPARC). The EoIs that are clustered
within this proposal will constitute key components of this programme
(consortium members are listed in section 4.2) which will include the
following specific components: (a) An Arctic measurement programme
will document the “state of the Arctic middle atmosphere
during the IPY (EoI 11, PASSMeC). This will use data from ground based
and satellite systems, centered on four lidar systems located at sites
across the Arctic. These lidar measurements will be coordinated with
satellite and radiosonde/ozonesonde measurements. These lidars are
distributed under different regimes of the Arctic middle atmosphere
and provide measurements that are critical for understanding the role
of tides, planetary and gravity waves in the large-scale
circulation. (b) A data assimilation, modelling and analysis component
will focus on assimilation and analysis of these observations to yield
a comprehensive picture of the observed circulation and facilitate
prediction of changes in the circulation and associated physical and
chemical responses. In addition this component will include archival
of assimilation products (analyses and forecasts) arising from
participating middle atmosphere assimilation groups during the IPY
period. Such products will be routinely produced at weather forecast
centers using models with vertical domains that extend above the
stratopause. Research groups employing chemistry transport models or
chemistry climate models will also participate. These activities are
critical for understanding the structure and evolution of the Arctic
vortex, the formation of polar stratospheric clouds, the depletion of
ozone, and the initiation of anomalous weather regimes associated with
the Arctic Oscillation. A specific component activity will include
analysis of the dynamics and chemistry associated with Stratospheric
Sudden Warmings (SSWs) in the Arctic Polar atmosphere during the IPY
(EoI 959, CMAM-IPY). The Canadian Middle Atmosphere Model (CMAM),
which extends from the ground to above the mesopause and includes
comprehensive and coupled chemistry, radiation and dynamics, will be
used to analyse SSWs during the IPY using a 3D-Var data assimilation
scheme. (c) Data available from instruments in operation at different
Antarctic and relevant continental sub polar sites in the southern tip
of South America, where the Antarctic polar vortex/ozone hole system
passes over inhabited regions, in combination with satellite
data. will be collected and interpreted. Organization of special
campaign periods will be promoted in collaboration with the various
national agencies involved in the operation of these sites. CTM runs
of relevant events using the AMR-CTM with the MECCA/MESSY chemistry
module (Argentina/UK/Germany) will be carried out. The SPARC-IPY
programme will also link with other closely related IPY activities
(see section 3.5). The services of the SPARC Data Center will be made
available to facilitate acquisition and archiving of key data that
will be used for projects or generated by them during the IPY period
(see section 3.6).