POLar study using Aircraft, Remote sensing data of Climate, Aerosols & Transport

Project Description
Short Title: POLARCAT
Project URL: http://www.polarcat.no/
Proposal URL:http://classic.ipy.org/development/eoi/proposal-details.php?id=32

The overall objective of POLARCAT, which proposes a coordinated programme of measurements and modelling, is to quantify the impact of trace gases, aerosols and mercury transported to the Arctic and their contribution to pollutant deposition and climate change in the region. POLARCAT has 5 major scientific objectives detailed in a White Paper, see http://zardoz.nilu.no/~andreas/POLARCAT/

1) Quantification of the major transport pathways controlling distributions of oxidants, aerosols, heavy metals together with their precursors/degradation products in the Arctic troposphere during winter-spring when Arctic Haze is prevalent and during summertime. Processes controlling the carbon budget at Northern high latitude forest/tundra/ocean regions will also be investigated.

2) Quantification of the optical properties and direct radiative effects of aerosols and their interactions with clouds and possible impacts on surface albedo and ice/snow cover.

3) Investigation into the influence of summertime boreal forest fires on the composition of the Arctic free troposphere compared to other source regions (e.g. Asia) including the impact of soot deposition on snow/ice albedo. The impact of pyro-convection on the composition/aerosol loading of the lower stratosphere and possible influences on stratospheric ozone depletion will also be investigated.

4) Determination of chemical processes controlling atmospheric composition, particularly during the winter and the spring-summer transition in the Arctic. This will include assessment of the nature and extent of ozone depletion events (link to halogen/mercury cycling) in the boundary layer; quantification of the role of VOCs and oxygenated species, relative roles of dry deposition and wet deposition of soluble species in rain- and snowfall, quantification of sources and sinks of major oxidants such as ozone and PAN including assessment of the odd-nitrogen budget. Also the chemistry and effect of polar air masses on mid- and high latitude particle formation is investigated.

5) Study of processes controlling inter-annual variations in atmospheric composition over the Arctic such as transport patterns (e.g. NAO) and changing emissions in different source regions. The impact of climate change on atmospheric composition and conversely the impact of atmospheric composition change on climate will also be investigated.