WORLD METEOROLOGICAL ORGANIZATION

UNITED NATIONS ENVIRONMENT PROGRAMME

LATVIA

The Republic of Latvia (area of 64,590km²) is situated in the western-most part of the Eastern European plain on the coast of the Baltic Sea, between 58 ° 05 and 55 ° 40 degrees of northern latitude and 20 ° 58 and 28 ° 14 degrees of eastern longitude.

The total ozone measurements started in Riga, the capital city of Latvia in 1961. In 1987 when a pollution source appeared in the immediate vicinity of the station, it was transferred to the outskirts of the city. The station has been regularly been contributing to the WMO Global Ozone Observing System (GO₃OS) and the data are deposited in the WMO-World Ozone Data Centre. In 1994, computerized ozone database was created in the Latvian Hydrometeorological Agency (LHMA).

The ozone station operates, since 1992, under the Nordic Ozone Group (NOG) as well and is involved in the creation of the common ozone database and information exchange of the observation and research activities. The next regular NOG meeting will be convened at LHMA Riga, 23-25 March 1996. Co- operation with NOG members includes regular data exchange with Denmark and Sweden. During the training exercise at the Finnish Meteorological Institute (FMI) in 1994, the finnish experience was mastered in the ozone measurements, data processing and analyzing .

The total ozone measurements in Latvia are made with the M-83 and M-124 (since 1985) ozonometers made in Russia. The Central Geophysical Observatory, St. Petersburg, Russia provides for calibration of these instruments.

The long-term atmospheric ozone measurements showed a mean annual value of 351 m atm cm (Dobson Unit). The lowest values were recorded in November (on average, 297 D.U.) and the highest in April (414 D.U.). The absolute maximum of 548 D.U. was measured on 11 and 12 May 1978 and the absolute minimum of 190 D.U. on 28 January 1992.

The analysis of data for the last 20 year period shows that ozone is gradually decreasing by 6% per 10 years on average. The decrease is observed throughout the year and is more marked in the cold period, 7% per 10 years on average. For summer, the value is 4% per 10 years. In the comparison analysis made for the two periods, 1976-1985 and 1986-1995, the latter shows a little faster decrease in the ozone amount. The most prominent were the years 1992 and 1993 when the mean monthly values reached 26% (one some days 46%) below normal but also very low ozone was recorded in the springs of 1995 and 1996.

The ozone issue has become a topic of interest in the general public. In view of this, the population has been informed of the ozone departures from normal, especially in the warm period of the year. Co-operatively with the Department of Health, information is provided on harmful impacts of UV-B and how to avoid this.

The restoration of independence in 1990 has brought about radical changes in the various life spheres of Latvia: now the economy of Latvia is in the transition period from central planning to market relations.

Despite the fact that it is not the true time to renew technologies and facilities to phaseout ozone depleting substances (ODS) from consumption and production, the Cabinet of Ministers of Latvia made the decision of 14 March 1995 to adhere to the Vienna Convention for the protection of the Ozone Layer, and its Montreal Protocol and approved a National ODS Phaseout Programme on the 29 August 1995. The Government of Latvia anticipates that due to close collaboration with the manufactures, co- operation among the states around the Baltic and implementation of the National Programme, CFCs, halons and carbon tetrachloride will be phased out by 2000.

With full compliance with Article 3. Monitoring of the Vienna Convention, the LMHA is establishing a complex and contemporary ozone monitoring system.

The surface ozone measurements have been made at the station at Rucava since February 1994 within the frames of the GAW (Global Atmosphere Watch)/EMEP (Co-operative Programme for Monitoring and Evaluation of the Long-Range Transmission of Air Pollutants in Europe) programmes.

Ozone concentrations are measured with the O₃41M UV-photometric analyzer (Environment S.A., France). The analyzer was calibrated in Tallinn, Estonia in 1995 with assistance from FMI. The test results were good. The surface ozone measurements have been reported to the Chemical Centre of EMEP, Norwegian Air Research Institute (NILU).

Recently we have launched a bilateral project with the Institute of Applies Environmental Research, Stockholm University with the aim to achieve the modern international standards of measurements and data quality to improve the interpretation and analysis of appropriate results.

With financial support from the Government of Finland, renewal of outdated equipment with the DIGICORA sounding system (Vaisala Oy, Finland) was completed at the station in Riga in January 1996. This will make ozone profile measurements possible. To start the measurements, additional funding is required to purchase special ozonesondes and facilities.

Replacement of the operated filter ozonometers by Brewer ozone spectrophotometers or other modern ozonometric equipment, could be a first step in modernization of the total ozone measurements and commencement of UV-B observations. A modernization project of the total ozone measurements, one of the VCP projects (OB/10/1 ) related to Latvia, has circulated among donors since May 1994, but has not received support.

Despite these difficulties, there are reasons (the long ozone measurements history and the accumulated experience and material) to believe that Latvia could be an ozone measurement and research centre for the new Baltic states.