WORLD METEOROLOGICAL ORGANIZATION

UNITED NATIONS ENVIRONMENT PROGRAMME

VIETNAM

1. INTRODUCTION

In resent years the activity for monitoring and research of atmospheric ozone and untraviolet radiation is developing rapidly. The amount of ozone station in Global ozone system (GO₃OS) have been increases. The system is upgraded. Nowadays, the system includes more than 300 station over all continents.

In the same time the activity for observation of untraviolet radiation has been developed in many countries. There are serious implication of depleted stratospheric ozone layer. Increasing of the penetration of untraviolet radiation on the earth's surface is expected to show of in medical statistics, regarding skin cancers and also raise the spectra of unpredictable damage to plants, algae and the global ecosystem.

For Vietnam, the research and monitoring of atmospheric ozone have begun since 1992.

2. CURRENT STATE OF OZONE AND UNTRAVlOLET RADIATION RESEARCH IN VIETNAM

Vietnam is located in the tropical belt. The country lasts from 8° 32' N to 93° 29' N and is under influence of monsoon. The change between the North circulation and the West circulation always happens in the area. Before 1992 generally there was not ozone stations in Indo-China and specially in Vietnam.

Since 1992 Vietnam has stated observing the total amount of the ozone and the untraviolet radiation. The network of ozone station is illustrated in figure 1.

In August 1992 the Hanoi station was established. The station is located in the 21° 02'N, 105° 5l'E and at the altitude of 5m above sea level.

In January 1994 the Sapa station was established. It's a station in the mountain area. The Sapa (22° 20'N, 103° 58'E) the altitude of station is 1.500m above sea level. The Sapa station was one of the experimental station in the international geophysical year 1957.

In November 1994 the Tan Son Hoa station (in Ho Chi Minh City) was opened with the coordinate of 10° 47'N, 106° 42'E and at the altitude of 5m above sea level.

In these stations the Russian filter ozonometer M. 124 has been used. The method of observing and processing are identical. The ozonometers has been calibrated every two years according to the instruction of the Russian main geophysical observatory.

Beside the total amount of ozone, all these stations also measure energy of untraviolet radiation UV-A and UV-B rays. The Hanoi station was accepted as a participating station to the world ozone data center (WODC) and we have regularly send the data to the center since January 1994. The observing data of Hanoi station shows that, the year average of total mount of ozone over Hanoi is 257 Dobson unit. In the hot season from March to August this value is higher than the one observed in the cold season. The same happens at Sapa and Tan Son Hoa station.

The Hydrometeorological Service of Vietnam expects to develop some ozone station in the place of low latitude and some station of untraviolet radiation in different climatic region of the country. This plan will give the data for the research of untraviolet radiation regime, necessary for ecology tourism and the medical service.

3. THE SHORTCOMING AND RECOMMENDATION

Our difficulties are low technical level. The observation and processing data is manually. Our ozone station measure only total amount of ozone. Recently in Hanoi and Tan Son Hoa stations there are Digicora equipments, which can carry out the vertical ozone sounding. As the expenditure for sounding is very high so we have not condition to do it.

Our expect is upgrading 3 stations, change instrument, automating process of observing and processing. We would like to carry out the vertical ozone sounding in some typical synoptic process, to do the research about the relation between the ozone change and the weather regime.

In order to release the situation we need the cooperation and with it's members assistance from WMO, from other international organization for instrument and training of cadres. We expect that with the effort of the cur Government and the international assistant our ozone station network will be completed and developed.