Circular No. 18/2022/TT-BTNMT stipulates the content of meteorological and hydrological observation for stations belonging to the national meteorological and hydrological station network.

CIRCULAR

Regulations on meteorological and hydrological observation content for stations within the national meteorological and hydrological station network

Pursuant to the Law on Meteorology and Hydrology dated November 23, 2015;

Pursuant to Decree No. 68/2022/NĐ-CP dated September 22, 2022 of the Government stipulating the functions, tasks, powers, and organizational structure of the Ministry of Natural Resources and Environment;

Pursuant to Decree No. 38/2016/NĐ-CP dated May 15, 2016 of the Government detailing certain provisions of the Law on Meteorology and Hydrology; Decree No. 48/2020/NĐ-CP dated April 15, 2020 of the Government amending and supplementing certain provisions of Decree No. 38/2016/NĐ-CP dated May 15, 2016 of the Government detailing certain provisions of the Law on Meteorology and Hydrology;

At the proposal of the Director General of the National Centre for Hydro-Meteorological Forecasting and the Head of the Legal Department;

The Minister of Natural Resources and Environment issues this Circular regulating the content of meteorological and hydrological observations for stations within the national meteorological and hydrological station network.

Article 1. Scope of Regulation

This Circular regulates the content of observations for stations within the national meteorological and hydrological station network as provided for in point b, Clause 2, Article 13 of the Law on Meteorology and Hydrology.

Article 2. Applicability

This Circular applies to agencies, organizations, and individuals related to the activities of observations at stations within the national meteorological and hydrological station network.

Article 3. Explanation of Terms

In this Circular, the following terms are understood as follows:

1. Basic meteorological and hydrological stations are: meteorological stations, hydrological stations, marine stations that conduct stable and long-term observations and play a core role in the national meteorological and hydrological station network. Observation data at these stations reflect the characteristics of meteorology, hydrology, and marine conditions in regions, sub-regions, or river basins and are used to check, evaluate, and compare observation data from other meteorological and hydrological stations in the same area; they are organized according to the model with observers.

2. Ordinary meteorological and hydrological stations are: meteorological stations, hydrological stations, marine stations arranged to increase the density of observations of some elements between basic stations as required for meteorological and hydrological forecasting and warning; these stations are organized for automatic observation without observers.

3. Reference meteorological and hydrological stations are selected from meteorological and hydrological stations with continuous observation periods of 30 years or more and can continue long-term observations, stations with technical safety corridors strictly adhering to current regulations; observation data at these stations represent a region, sub-region, area, or river basin and can be used as a basis for comparing and evaluating trends in changes of meteorological, hydrological, and marine elements caused by climate change. In addition to observing elements like selected meteorological stations, reference meteorological stations also observe atmospheric component elements and other elements as prescribed.

4. Basic meteorological, hydrological, and marine stations are equivalent to Class 1 stations; ordinary meteorological stations are equivalent to Class 3 meteorological stations; ordinary hydrological stations measuring water flow are equivalent to Class 2 hydrological stations, ordinary hydrological stations not measuring water flow are equivalent to Class 3 hydrological stations; ordinary marine stations are equivalent to Class 2 marine stations.

Manual measurement and transmission equipment are technical means for conducting measurements, transmitting information, and data on meteorological and hydrological factors and using human resources to implement them.

Article 4. Principles of Implementation

1. The content of observations for stations within the national meteorological and hydrological station network includes: observed factors, observation schedules, and information and data transmission schedules.

2. Under normal meteorological and hydrological conditions, stations shall conduct observations and transmit information and data on meteorological and hydrological observations in accordance with Articles 6, 7, and 8 of this Circular.

3. Under dangerous meteorological and hydrological conditions, the National Centre for Hydro-Meteorological Forecasting decides to strengthen observation schedules and information and data transmission schedules for meteorological and hydrological observations at stations to meet requirements for meteorological and hydrological forecasting and warning.

4. The time for conducting observations and transmitting information and data on meteorological and hydrological observations in this Circular is regulated according to Hanoi time (GMT + 7).

Article 5. Stations belonging to the national meteorological and hydrological station network

1. Surface meteorological stations, including:

a) Basic meteorological stations;

b) General meteorological stations.

2. Upper-air meteorological stations, including:

a) Radio sounding stations;

b) Upper-air wind measurement stations.

3. Weather radar stations.

4. Hydrological stations, including:

a) Basic hydrological stations;

b) General hydrological stations.

5. Marine stations, including:

a) Basic marine stations;

b) General marine stations.

6. Rainfall measurement stations.

7. Lightning location stations.

8. Other specialized stations:

a) Radiation stations;

b) Ozone and ultraviolet radiation stations;

c) Stratified ozone monitoring stations;

d) Meteorological satellite image receiving stations;

đ) Salinity measurement stations.

9. Climate change monitoring stations, including:

a) Reference meteorological stations;

b) Reference hydrological stations;

c) Reference marine stations;

d) Independent climate change monitoring stations.

Article 6. Elements monitored in meteorological and hydrological observations

1. Basic meteorological stations monitor all elements:

a) Surface wind;

b) Air temperature (average, highest, lowest);

c) Air humidity;

d) Atmospheric pressure;

đ) Rainfall;

e) Clouds;

g) Evaporation (from wet surfaces, water surfaces);

h) Horizontal visibility;

i) Ground surface temperature (average, highest, lowest);

k) Sunshine duration;

l) Meteorological phenomena;

m) Ground surface condition.

2. General meteorological stations monitor surface wind, air temperature, air humidity, atmospheric pressure, and rainfall. Depending on the observation purposes and requirements of the station, additional elements from point e to point k may be selected, or only surface wind and some elements from point b to point đ of Clause 1 of this Article may be monitored.

3. Surface meteorological stations that monitor agricultural meteorology select additional observation elements: soil temperature at different depths; soil moisture at various depths; photosynthetic radiation; leaf wetness; evaporation (from water surfaces); actual evapotranspiration (of grass cover). In cases where observations serve agricultural development needs according to the requirements of Ministries, sectors, or localities, other elements may be added as needed.

4. Radio sounding stations monitor:

a) Surface meteorological elements: atmospheric pressure; air temperature; air humidity; wind; clouds; meteorological phenomena;

b) Upper-air meteorological elements: air temperature; air humidity; atmospheric pressure; wind and geopotential height.

5. Upper-air wind measurement stations monitor:

a) Surface meteorological elements: atmospheric pressure; air temperature; air humidity; wind; clouds; meteorological phenomena;

b) Upper-air wind.

6. Weather radar stations monitor the following elements:

a) Cloud fields;

b) Rain fields;

c) Wind convergence fields.

7. Basic hydrological stations monitor all elements:

a) Water level;

b) Rainfall amount;

c) Water temperature;

d) Flow rate;

đ) Suspended sediment load.

8. General hydrological stations monitor water level and some elements from point b to point đ of Article 7 of this Law depending on the information and data requirements of the station.

9. Basic marine stations monitor all elements:

a) Sea level;

b) Sea waves;

c) Surface sea wind;

d) Surface sea water temperature;

đ) Long-range sea visibility;

e) Sea water salinity;

g) Sea brightness;

h) Sea current;

i) Dangerous and extremely dangerous marine meteorological phenomena.

10. General marine stations monitor sea level and some elements from point b to point i of Article 9 of this Law depending on the information and data requirements of the station.

11. Rainfall measurement stations monitor: rainfall amount.

12. Lightning location stations monitor: lightning (lightning intensity, type).

13. Radiation stations monitor the components of the radiation element:

a) Direct radiation;

b) Diffuse radiation;

c) Shortwave total radiation;

d) Longwave total radiation;

đ) Shortwave reflected radiation;

e) Longwave reflected radiation.

14. Ozone and ultraviolet radiation stations monitor the following elements:

a) Total atmospheric ozone;

b) Ultraviolet radiation intensity.

15. Stratified ozone monitoring stations monitor the following elements:

a) Ozone quantity at each layer;

b) Total ozone quantity of the entire atmospheric layer.

16. Meteorological satellite image receiving stations collect cloud images and other meteorological satellite images.

17. Salinity measurement stations monitor the following elements:

a) Salinity;

b) Ancillary factors: water temperature; water level; depth of the measuring point and collecting information on rainfall amounts; weather conditions, location, characteristics of river sections (riverbed erosion, discharges from both sides of the river), saltwater intrusion situations in previous years.

18. Reference meteorological stations monitor the following elements:

a) Meteorological elements of selected meteorological stations;

b) Some greenhouse gas elements: Carbon dioxide (CO2), Carbon monoxide (CO), Methane (CH4), water vapor (H2O), Ozone (O3) and other elements as required.

19. Reference hydrological stations monitor the elements of selected hydrological stations.

20. Reference marine stations monitor the elements of selected marine stations.

21. Independent climate change monitoring stations monitor some greenhouse gas elements: Carbon dioxide (CO2), Carbon monoxide (CO), Methane (CH4), water vapor (H2O), Ozone (O3), Aerosols and other elements as required.

Article 7. Monitoring Regime at Meteorological and Hydrological Stations

1. The monitoring regime using manual measurement instruments for surface meteorological factors specified in Clause 1, Article 6 of this Circular, specifically as follows:

a) Factors specified from Point a to Point e and Point l shall be monitored eight times a day at full hours 01, 04, 07, 10, 13, 16, 19, and 22.

b) Factors specified in Points h and i shall be monitored four times a day at full hours 01, 07, 13, and 19.

c) Factors specified in Points g and m shall be monitored two times a day at full hours 07 and 19.

d) The factor specified in Point k shall be monitored once a day at full hour 19.

e) In the case of international reporting stations, the factor specified in Point h shall be additionally monitored eight times a day.

2. The monitoring regime using manual measurement instruments for surface meteorological factors specified in Clause 2, Article 6 of this Circular, specifically as follows:

a) Factors specified from Point a to Point e, Point h, and Point i of Clause 1, Article 6 of this Circular shall be monitored four times a day at full hours 01, 07, 13, and 19.

b) The factor specified in Point g of Clause 1, Article 6 of this Circular shall be monitored two times a day at full hours 07 and 19.

c) The factor specified in Point k of Clause 1, Article 6 of this Circular shall be monitored once a day at full hour 19.

3. The monitoring regime using manual measurement instruments for agricultural meteorological factors at surface meteorological stations specified in Clause 3, Article 6 of this Circular, specifically as follows:

a) Factors such as soil temperature at different depths, soil moisture at various depths, photosynthetic radiation, and leaf wetness shall be monitored four times a day at full hours 01, 07, 13, and 19.

b) The evaporation factor (surface water) shall be monitored two times a day at full hours 07 and 19.

c) The actual vapor pressure deficit (Lyzimet) factor shall be monitored at full hour 19.

d) In the case of stations monitoring factors to serve local agricultural development needs, the monitoring regime should be selected appropriately.

4. The monitoring regime using manual measurement instruments at radio-sounding stations: depending on the requirements for data usage, the monitoring regime shall be carried out according to the following regimes: monitoring up to four times a day at 01, 07, 13, and 19 hours; monitoring twice a day at 07 and 19 hours; monitoring once a day at 07 hours.

5. The monitoring regime using manual measurement instruments at upper-air wind measurement stations: once a day at 07 or 13 hours.

6. The monitoring regime using manual measurement instruments for hydrological factors specified in Clauses 7 and 8, Article 6 of this Circular, specifically as follows:

a) Water level, water temperature, and rainfall factors shall be implemented according to the provisions in Appendix I attached to this Circular.

b) Flow rate factors shall be implemented according to the provisions in Appendix II attached to this Circular.

c) Suspended sediment flow rate factors shall be implemented according to the provisions in Appendix III attached to this Circular.

7. The monitoring regime using manual measurement instruments for marine factors specified in Clause 9, Article 6 of this Circular, specifically as follows:

a) Factors specified in Points a, c, d, đ, and e shall be monitored four times a day at full hours 01, 07, 13, and 19.

b) The factor specified in Point b shall be monitored three times a day at full hours 07, 13, and 19.

c) The factor specified in Point g shall be monitored two times a day at 01 and 19 hours.

d) The factor specified in Point i shall be continuously observed and monitored throughout the day.

đ) The factor specified in Point h shall be monitored according to the following regimes based on the requirements for weather forecasting: monitoring four times a day at 01, 07, 13, and 19 hours; monitoring eight times a day at 01, 04, 07, 10, 13, 16, 19, and 22 hours; monitoring twelve times a day at odd hours from 01 to 23.

8. The monitoring regime using manual measurement instruments for marine factors specified in Clause 10, Article 6 of this Circular, specifically as follows: the monitoring regime shall be selected appropriately according to the factors being monitored at the station, as provided in Clause 7 of this Article.

9. The monitoring regime using manual measurement instruments at rain gauging stations:

a) During the dry season, monitoring shall be conducted twice a day at full hours 07 and 19.

b) During the rainy season, monitoring shall be conducted four times a day at full hours 01, 07, 13, and 19.

10. Salinity monitoring stations shall implement the monitoring regime as prescribed in Clause 2, Article 7 of Circular No. 39/2016/TT-BTNMT dated December 19, 2016, issued by the Minister of Natural Resources and Environment, concerning technical regulations on salinity intrusion monitoring and investigation.

11. Reference meteorological stations shall follow the monitoring regime of the selected station.

12. Reference hydrological stations shall follow the monitoring regime of the selected station.

13. Reference marine stations shall follow the monitoring regime of the selected station, with the exception that the sea level factor shall be strengthened to monitor 24 times a day at full hours from 00 to 23.

14. Stations using automatic measurement instruments or when manual measurement instruments are replaced by automatic equipment: continuous monitoring 24/24 hours.

Article 8. Information and data transmission regime at meteorological and hydrological stations

1. The information and data transmission regime using manual transmission means for surface meteorological elements specified in Clause 1, Article 6 of this Circular is as follows: SYNOP telegrams are sent eight times a day at 01 hours, 04 hours, 07 hours, 10 hours, 13 hours, 16 hours, 19 hours, and 22 hours; CLIM telegram is sent once a month at 19:30 on the last day of the month; CLIMAT telegram is sent once a month at 20:00 on the last day of the month; agricultural meteorological elements are transmitted immediately upon completion of observation.

2. The information and data transmission regime using manual transmission means for surface meteorological elements specified in Clause 2, Article 6 of this Circular is as follows: SYNOP telegram is sent four times a day at 01 hours, 07 hours, 13 hours, and 19 hours; CLIM telegram is sent once a month at 19:30 on the last day of the month.

3. The information and data transmission regime using manual transmission means at unmanned radio sounding stations: transmission is carried out immediately after each observation period and CLIMATTEMP telegram is sent once a month during the last observation period of the month.

4. The information and data transmission regime using manual transmission means at upper air wind measurement stations: transmission is carried out immediately upon completion of observation. In cases where upper air wind measurement is conducted via radio methods, CLIMATTEMP telegram is additionally sent once a month during the last observation period of the month.

5. The information and data transmission regime using manual transmission means for hydrological elements specified in Clause 7, Article 6 of this Circular is as follows: stations listed in the telegraph station list for weather and hydrological forecasting transmit information and data immediately upon completion of the observation.

6. The information and data transmission regime using manual transmission means for hydrological elements specified in Clause 8, Article 6 of this Circular is as follows: the transmission regime is selected based on the observed element at the station according to the provisions of Clause 5 of this Article.

7. The information and data transmission regime using manual transmission means for marine elements specified in Clause 9, Article 6 of this Circular is as follows: transmission is carried out four times a day at 01 hours, 07 hours, 13 hours, and 19 hours.

8. The information and data transmission regime using manual transmission means for marine elements specified in Clause 10, Article 6 of this Circular is as follows: the transmission regime is selected based on the observed element at the station according to the provisions of Clause 7 of this Article.

9. The information and data transmission regime using manual transmission means at rainfall measurement stations: transmission is carried out immediately after the completion of each observation.

10. Salinity measurement stations implement the information and data transmission regime immediately after the completion of the final salinity measurement in a measurement series on days when salinity is measured.

11. Reference meteorological stations implement the information and data transmission regime of the chosen station.

12. Reference hydrological stations implement the information and data transmission regime of the chosen station.

13. Reference marine stations implement the information and data transmission regime of the chosen station.

14. Stations equipped with automatic measuring devices or when manual measuring devices are replaced by automatic equipment have the following information and data transmission regimes:

a) Lightning location stations transmit at least once every five minutes at the following minutes (00 minutes, 05 minutes, 10 minutes, ..., 55 minutes).

b) Upper air meteorological stations, climate change monitoring stations, and radiation stations transmit at least once every hour at full hours (00 hours, 01 hours, ..., 23 hours).

c) Other meteorological and hydrological stations transmit at least once every ten minutes at full ten-minute intervals (00 minutes, 10 minutes, 20 minutes, ..., 50 minutes).

d) Depending on the capabilities of the equipment, observation technology, and the capacity of the specialized meteorological and hydrological information system, the appropriate information and data transmission regime is selected.

Article 9. Responsibility for implementation

Agencies and units directly managing national meteorological and hydrological stations are responsible for reviewing and evaluating the observational elements, observers, infrastructure, and measuring instruments of existing surface meteorological, hydrological, and marine stations, and developing plans to submit to competent authorities for consideration and decision-making regarding the supplementation or reduction of observational elements to classify basic meteorological, hydrological, and marine stations and general stations according to the provisions of this Circular.

Article 10. Effective Date

This Circular takes effect from January 9, 2023, and replaces Circular No. 05/2016/TT-BTNMT dated May 13, 2016, issued by the Minister of Natural Resources and Environment on the content of meteorological and hydrological observations for stations within the national meteorological and hydrological station network.

Article 11. Implementation Organization

1. Ministries, ministerial-level agencies, agencies under the Government, People's Committees of provinces and centrally-administered cities, and related organizations and individuals are responsible for implementing this Circular.

2. The Director of the General Department of Meteorology and Hydrology is responsible for assisting the Minister of Natural Resources and Environment in guiding, urging, and inspecting the implementation of this Circular./.