Ozone layer and UV radiation in a changing climate evaluated during IPY

Project Description
Short Title: ORACLE-O3
Proposal URL: http://classic.ipy.org/development/eoi/proposal-details.php?id=99

The depletion of the polar ozone layer is one of the strongest anthropogenic signals in the earth system. The IPY will approximately take place during the period of peak concentrations of man-made ozone depleting substances in the region of the ozone layer. It is also the time when potential effects from climate change, e.g. changes in temperature, water vapour abundances, and/or circulation, might begin to manifest in the stratosphere and influence ozone recovery. In April 2005, nearly eighteen years after the signing of the Montreal Protocol (MP), ozone loss is as severe as ever over the Arctic, and the timing and extent of ozone recovery is uncertain. Depletion of stratospheric ozone in polar regions has greatly enhanced harmful UV radiation in the affected areas at times of the year when ecosystems are vulnerable. The state of the polar stratosphere, and its future development will be, therefore, a major source of concern, both for circumpolar communities and people living at lower latitudes in the International Polar Year (IPY) and for decades thereafter.

The project will be divided into seven main activities:

1) ozone loss (detection and impact on UV radiation,
2) PSC (polar stratospheric clouds) and cirrus,
3) atmospheric chemistry,
4) UV radiation,
5) ozone and climate change and feedback,
6) data management, and
7) education, outreach and communication.

The project implies precisely quantification of polar ozone losses in both hemispheres achieved with concerted international campaigns during which hundreds of ozonesondes will be launched in real-time coordination from station networks in the Arctic and Antarctic. Satellite coverage of ozone and ozone depleting substances will be unprecedented during the IPY, and data from satellites such as ENVISAT, Aura, ACE, Odin, POAM III and SAGE III will be used in a novel approach that combines these measurements with groundbased station data.

Understanding ozone depletion requires an understanding of PSCs which are known to initiate ozone depletion through heterogeneous reactions and enhance ozone depletion through removal of nitric acid (denitrification) by cloud sedimentation. Chemical, microphysical, and optical properties of polar cloud particles and gas phase species will be obtained in-situ and remotely from stratospheric balloons and several aircraft, including the high altitude research aircraft Geophysica during a major Arctic field campaign. Complementary particle information will be gained by lidar observations from several Arctic and Antarctic NDSC (Network for the Detection of Stratospheric Change) research stations, including the development of PSC detection capabilities with the satellite borne CALIPSO lidar.

During the project ground-based observations will be performed at many Arctic and Antarctic NDSC-stations by means of remote sensing instruments operating in the infrared, UV/Vis and microwave spectral regions to measure the seasonal and long-term variability of ozone, water vapour, and numerous key ozone-related trace gases in the stratosphere, in addition to tropospheric pollutants, greenhouse gases, and biomass burning. Radiosonde, lidar and satellite will provide measurements of wind and temperatures in the troposphere, stratosphere and mesosphere. The project also comprehends monitoring of UV-, visible, and infrared radiation and ground/sea/ice albedo in various high latitude stations in the northern and southern hemisphere together with modelling studies of ozone and UV in these regions, including an epidemiological study of personal UV exposure.

Integration of field data and process studies within a modelling framework will enable predictions the future evolution of the ozone layer as well as the potential feedback on the future polar climate. The modelling efforts will focus on assimilating the observations to yield a comprehensive understanding that can both reproduce the observed circulation and chemical evolution and predict the Arctic and Antarctic middle atmosphere response to changes in the circulation and atmospheric chemistry. Atmospheric effects of manifestations of solar activity as the short-term changes of the cosmic ray intensity, variations of the interplanetary electric field and variations of the solar UV-irradiation will be included. Interactively coupled chemistry-climate models (CCMs) of the troposphere and the stratosphere will be used to investigate past and to assess future changes of climate and atmospheric chemical composition at higher geographical latitudes of the Earth atmosphere, particularly of ozone recovery in the stratosphere. Related changes of solar ultraviolet (UV) radiation will be determined.