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SCAR Bulletin No 134, July 1999

Working Group on Physics and Chemistry of the Atmosphere

Ten members and five observers attended the meeting.

1. Activities during the PACA meeting

Three symposia were held during 20-24 July 1998:

a) Stratospheric and Tropospheric Chemistry

On Monday 20 July 1998 a workshop on chemistry of the atmosphere was held with presentations on many aspects of the subject by representatives of the UK, Canada, Japan, Italy, Brazil and Chile. The presentations were aimed at showing the different activities that are carried out in atmospheric chemistry by countries active in Antarctica. The research covered: monitoring of greenhouse gases, characterisation of aerosols and pollutants, comparison between the present day pollution and information obtained from ice cores, radon monitoring, ozone in the troposphere and stratosphere. With reference to this last item, a presentation was given on the APE-GAIA project that foresees the use of the stratospheric aircraft Geophysica to carry out flights in the stratosphere in 1999 between 1 September and 15 October to collect data in situ during the period of ozone depletion and recovery. Regarding ozone, a presentation was given showing that Antarctic ozone depletion begins at mid-winter in the more northerly parts of the Antarctic. An information paper was presented by Uruguay on its ozone activities that had begun this year.

b) Antarctic First Regional Observing Study of the Troposphere (FROST) project

A workshop was held on Tuesday 21 July to review the achievements of FROST. A detailed assessment of the state of FROST is given below.

c) Spatial and Temporal Variability of Antarctic Precipitation

Five presentations considered precipitation trends at the northern tip of the antarctic Peninsula, continent-wide estimates of accumulation from atmospheric numerical analyses, and interannual precipitation variations in Dronning Maud Land and West antarctica. The importance of major synoptic events for accumulation at selected inland areas was highlighted. A major item of concern that emerged was the large differences between different numerical analyses produced by the European Centre for Medium-range Weather Forecasts (ECMWF). This represents a significant obstacle to enhanced understanding of precipitation variability and change in Antarctica. Resolution of these differences is urgent because of the 40 year re-analysis scheduled to commence in mid-1999. This is likely to become the premier global data set for investigations of climate variability and a faithful representation of the Antarctic atmosphere is essential.

It is planned to have an issue of the US AGU geophysical research series devoted to papers from the symposium. Papers should be submitted by the end of March 1999.

2. Status of the FROST Project.

Excellent progress has been made with the Antarctic First Regional Observing Study of the Troposphere (FROST) project, which has been the major focus of PACA since 1992. Achievements include:

  1. Establishment of a large database of Antarctic observations for three special observing periods in 1994-95.
  2. Identification and correction of problems on the Global Telecommunications System concerned with the transmission of Antarctic observations.
  3. Investigation of differences between the Antarctic analyses produced by the major weather services.
  4. Collaboration with the weather services on improving the representation of the Antarctic in their models.
  5. Correction of a major misrepresentation of orographic height in the operational numerical models.

FROST is planned to draw to a close in 2000 and a full report will be provided to the Delegates at XXVI SCAR.

Special issues of the American Meteorological Society journal Weather and Forecasting and the Australian Meteorological Magazine are planned on FROST.

3. New programmes

The following new initiatives are being considered:

a) Reference Antarctic Data for Environmental Research (READER)

The Working Group agreed to produce the best climatological fields for Antarctica of key variables, such as near-surface temperature, wind velocity, cloud cover/long wave radiation, single station analyses of upper atmosphere temperature trends from radiosonde data (including cooling in the lower stratosphere) etc.

b) Atmospheric chemistry

The Working Group recognised that new initiatives in atmospheric chemistry are desirable. As a first step the chemists within the group have been asked to consider potential new activities in this field that could be pursued.

Details of these initiatives will be finalised at XXVI SCAR. Interested parties should contact the PACA Chairman.

4. Officers of PACA

The following officers were elected:

Chairman J Turner (UK)

Vice-Chairman E B Pereira (Brazil)

Secretary H Hutchinson (australia)

Webmaster D Bromwich (USA)

5. Actions on XXIV SCAR

  1. The Working Group is pleased to note that the GLOCHANT programme and in particular ITASE and ASPECT have been well-supported and are being implemented.
  2. Although some progress has been made in getting observations from tourist vessels onto the GTS, possible improvements could still be made.
  3. Around 70 AWSs now have their observations on the GTS, which provide reasonable cover, especially in the Antarctic coastal region. There is, however, concern over the AGO data (see recommendation below).
  4. The Working Group notes with concern that the number of upper air stations is decreasing at the present time. Since the closure of Leningradskaya in 1991, six upper air stations have closed, one on Campbell Island and the rest on the Antarctic continent.
  5. The Working Group is pleased to note that the International Antarctic Drifting Buoy programme has coordinated and encouraged the deployment of buoys in the Southern Ocean and sea ice zone.
  6. The Working Group notes the improvements that have taken place in the GTS over the last two years but stresses the need for continuing to monitor the system and the timely insertion of data using satellite communications.

6. SCAR XXVI

PACA plans to meet at XXVI SCAR and to hold the following symposia:

Recommendations

1) Concerning a Working Group on physical and chemical oceanography.

Noting the great importance of studies concerned with air-sea interactions to Antarctic climatology.

The PACA Working Group recommends that SCAR, as a matter of policy, includes physical and chemical oceanography within its organisational framework.

3) Upper Air Meteorological Profiles.

Recognising that:

PACA recommends to National Committees on Antarctic Research that they should maintain their existing upper air sounding programmes (at least at 00 GMT or 12 GMT, but preferably both). Sites that would be ideal for the commencement of upper air meteorological measurements are Byrd (ceased upper air soundings in 1979), Vostok (ceased upper air soundings in 1992), and the recently settled sites of Dome Concordia and Dome Fuji.

4) Clouds and Energy Balance Studies.

Considering the importance of radioactive and energy balance on climatic and meteorological models of the global atmosphere and that the role of polar clouds is ill-defined;

PACA recommends that National Committees support efforts to obtain systematic data of the energy balance and physical properties of cloud cover over Antarctica.

6) GLOCHANT Workshop in New Hampshire.

Noting the importance of modern climatological knowledge for calibration of the paleoclimate records from the ice sheet and the Southern Ocean to be produced from the ITASE Project;

PACA Working Group recommends that SCAR supports the GLOCHANT Workshop on "Recent Antarctic Climate History" in New Hampshire, USA, April 1999, by funding the participation of the PACA Chairman.

7) GLOCHANT Cambridge Workshop.

Recognising the importance of the atmospheric and and oceanic impacts on Antarctica;

PACA Working Group recommends that SCAR support the GLOCHANT Workshop on "Large-Scale Variability in the Southern Ocean: Patterns, Mechanisms and Impacts", in Cambridge, UK, July 1999, by supporting the participation of the PACA Chairman.

9) European Centre for Medium-Range Weather Forecasts (ECMWF) Atmospheric Re-analyses.

Noting:

The WG recommends that all National Committees on Antarctic Research note that PACA will be working with ECMWF to resolve these discrepancies, as a matter of urgency.

12) Stratospheric meteorology and ozone chemistry.

Noting that:

The Working Group recommends that National Committees on Antarctic Research encourage cooperation with Dr. Gernandt to achieve his goals with respect to the STRATEOLE project.

(Note: PACA Recommendations 2,5,8,10 and 11 were adopted as SCAR Recommendations XXV-16, XXV-17, XXV-18, XXV-19 and XXV-20).