Circular No. 15/2022/TT-BTNMT on technical regulations for weather radar monitoring and ultraviolet radiation monitoring

CIRCULAR

TECHNICAL REGULATIONS ON WEATHER RADAR MONITORING AND OZONE ULTRAVIOLET RADIATION

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

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 articles of Decree No. 38/2016/NĐ-CP dated May 15, 2016 of the Government detailing certain provisions of the Law on Meteorology and Hydrology;

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;

At the proposal of the Director General of the National Centre for Hydro-meteorological Forecasting, the Head of the Science and Technology Department and the Head of the Legal Department;

The Minister of Natural Resources and Environment issues this Circular prescribing technical regulations on weather radar monitoring and ozone ultraviolet radiation.

PART I

GENERAL PROVISIONS

Article 1. Scope of Regulation

This Circular prescribes technical regulations on weather radar monitoring and ozone ultraviolet radiation.

Article 2. Applicability

This Circular applies to agencies, organizations, and individuals related to weather radar monitoring and ozone ultraviolet radiation activities.

Article 3. Explanation of Terms

In this Circular, the following terms shall be understood as follows:

1. Conventional weather radar is a radar that measures only the intensity of radio wave reflections and cannot measure the speed of target movement in a single measurement.

2. Doppler weather radar is a radar that measures both the intensity of radio wave reflections and uses the Doppler principle to measure the speed of moving targets and centripetal winds.

3. Dual-polarization weather radar is a radar that emits energy in both horizontal and vertical directions.

4. Weather radar operating in the S-band operates at wavelengths from 7.5 cm to 15 cm, frequencies from 2 GHz to 4 GHz.

5. Weather radar operating in the C-band operates at wavelengths from 3.75 cm to 7.5 cm, frequencies from 4 GHz to 8 GHz.

6. Weather radar operating in the X-band operates at wavelengths from 2.5 cm to 3.75 cm, frequencies from 8 GHz to 12 GHz.

7. Fixed weather radar system is a radar equipment system installed at a fixed location for monitoring and data collection.

8. Mobile weather radar system is a radar equipment system installed on specialized vehicles that move to different locations for monitoring and data collection.

9. Full circular scan (360 degrees) with a fixed elevation angle (PPI) is a scanning mode at a selected antenna elevation angle chosen by the user.

10. Vertical scan at a fixed azimuth angle (RHI) is a scanning mode along the vertical direction at a selected antenna azimuth angle chosen by the user.

11. Volume scan involves performing multiple consecutive full circular scans with different fixed elevation angles.

12. Volume scan product is the product generated from the volume scan when conducting monitoring.

13. Derived product is the product created through software provided by the radar manufacturer from the volume scan product.

14. Doppler wind is crosswind component determined through the frequency shift between transmitted and received signals or phase shift changes among signals – Doppler effect.

15. Total atmospheric ozone column is the total amount of ozone in the vertical column of the atmosphere from the ground surface to the upper limit of the atmosphere having a cross-sectional area of 0.0001 m² under standard temperature and pressure conditions.² (10^-4 t s²at standard temperature and pressure conditions.

16. Ultraviolet radiation (also known as ultraviolet light) is the short-wave radiation from the sun within the spectral range from 5 nm to 400 nm, ultraviolet radiation on the ground is measured from 100 nm upwards, divided into three types: ultraviolet A (UVA) 315 nm - 400 nm, ultraviolet B (UVB) 280 nm - 315 nm, and ultraviolet C (UVC) 100 nm - 280 nm.

Chapter II

WEATHER RADAR MONITORING

Article 4. Position, monitoring facilities

1. Fixed weather radar

The position and monitoring facilities shall be implemented in accordance with the contents of 4.4 and 5.4 of TCVN 12635-4:2021, Part 4: Position and monitoring facilities for high-altitude meteorological stations, ozone-ultraviolet radiation, and weather radar.

2. Mobile weather radar

The monitoring position must have an area suitable for the size of the mobile radar; a flat surface; a solid structure to ensure the deployment, installation, and monitoring according to the purpose and requirements.

Article 5. Factors, units of measurement, and permissible errors

1. Weather radar

2. Doppler weather radar

3. Dual-polarization weather radar

Article 6. Monitoring and data provision

1. Technical parameters for setting up monitoring schedules:

a) Volume scanning mode

Table 1. Volume scanning mode of S-band weather radar

Table 2. Volume scanning mode of C-band weather radar

Table 3. Volume scanning mode of X-band weather radar

b) Vertical scanning mode

Table 4. Vertical scanning mode

c) Fixed arc circular scanning mode

Parameters taken from volume scanning mode and supplemented with starting and ending angle parameters of the circular arc to be monitored. Starting and ending angle parameters range from 0 to 360 degrees.

2. Steps for monitoring:

a) Install the system;

b) Power on the system;

c) Start the weather radar system and auxiliary equipment;

d) Set up monitoring mode, schedule monitoring, and transmit data;

e) Run the monitoring program according to the established schedule;

g) Display monitoring data and products;

h) Dismantle and package the equipment;

i) For fixed weather radars, steps a and h of paragraph 2 of this article shall not be performed;

k) Detailed steps for monitoring according to technical documentation of each type and manufacturer of weather radar.

3. Monitoring sequence:

a) Implement volume scanning mode: the schedule is pre-set. In the volume scanning schedule, set the radio echo intensity monitoring mode first. After completing the radio echo intensity monitoring mode, switch to the Doppler wind monitoring mode;

b) Implement vertical scanning mode: based on needs and purposes, the vertical scanning mode is carried out according to the pre-set schedule or a schedule established according to professional requirements. The vertical scanning schedule is interspersed during the downtime between two volume scanning schedules;

c) Implement fixed arc circular scanning mode: based on needs and purposes, decide on appropriate monitoring.

4. Operation and monitoring modes:

a) Operation mode: continuous 24/24 hours, except for maintenance, servicing, and calibration periods conducted in accordance with Circular No. 57/2014/TT-BTNMT dated October 10, 2014, issued by the Minister of Natural Resources and Environment, stipulating technical standards for calibration, inspection, maintenance, and periodic storage of high-altitude meteorological equipment, and economic-technical norms for regular maintenance and inspection of high-altitude meteorological equipment;

b) Volume scanning monitoring mode: maximum frequency of once every 10 minutes at full minutes (0 minutes, 10 minutes, 20 minutes...50 minutes). Vertical scanning and fixed arc circular scanning modes will depend on needs and purposes, and will be selected for appropriate monitoring.

5. Data Provision

Scanned data in various scanning modes (volume scanning, vertical scanning, or fixed arc circular scanning if applicable) shall be provided immediately after monitoring. In case of transmission issues, supplementary provision shall be made once the issue is resolved.

Article 7. Submission of Monitoring Results and Activity Reports

1. The monitoring results of each month shall be controlled, stored on electronic media, and sent to the management unit before the 5th day of the following month.

2. Reports:

a) Periodic reports: Each station shall prepare monthly reports according to the model prescribed in Appendix I of this Circular and send them to the management unit before the 5th day of the following month;

b) Emergency reports: In case of technical incidents or upon completion of monitoring hazardous weather phenomena, the station must immediately report to the management unit via telephone or other communication means; within three days, submit a written report to the aforementioned unit.

3. For stations belonging to the specialized meteorological and hydrological station network: implement the provisions regarding monitoring and providing meteorological and hydrological information and data for specialized meteorological stations.

Chapter III

ULTRAVIOLET RADIATION MONITORING - ULTRAVIOLET RADIATION

Article 8. Location and Monitoring Facilities

Implement according to the provisions of items 4.3 and 5.3 of TCVN 12635-4:2021, Part 4: Location and Monitoring Facilities for High-altitude Meteorological Stations, Ozone - Ultraviolet Radiation, and Weather Radar.

Article 9. Factors, Units of Measurement, and Permissible Errors

1. Factors and Units of Measurement:

a) Total atmospheric ozone: measured in DU (Dobson units).

The Dobson unit is a measurement unit for ozone in the atmosphere, particularly in the stratosphere. One Dobson unit equals 2.69 x 10¹⁶ ozone molecules per square centimeter or 2.69 x 10²⁰ ozone molecules per square meter, equivalent to a layer of ozone 10^-5 meters thick under standard temperature and pressure conditions (0 °C and 100 kPa);

b) Intensity of ultraviolet radiation: measured in mW/m².

2. Permissible Errors

Implement according to point 7.1, TCVN 12636-5:2020, Part 5 - Monitoring of Total Atmospheric Ozone and Ultraviolet Radiation.

Article 10. Monitoring and Provision of Data

The equipment for monitoring total atmospheric ozone and ultraviolet radiation intensity operates 24/24 hours, conducting monitoring from sunrise to sunset. Data is provided online to the specified address.

Article 11. Submission of Monitoring Results and Activity Reports

1. Data shall be provided immediately after monitoring; the monitoring results of each month shall be controlled, summarized, and sent to the management unit before the 3rd day of the following month.

2. Reports:

a) Periodic reports: Each station shall prepare monthly reports according to the model prescribed in Appendix II of this Circular and send them to the management unit before the 3rd day of the following month;

b) Emergency reports: In case of technical incidents or incidents during monitoring, the station must immediately report to the management unit via telephone or other communication means; within three days, submit a written report to the direct management unit for handling.

3. For stations belonging to the specialized meteorological and hydrological station network: implement the provisions regarding monitoring and providing meteorological and hydrological information and data for specialized meteorological stations.

Chapter IV

IMPLEMENTATION

Article 12. Effective Date

1. This Circular takes effect from December 12, 2022.

2. This Circular replaces Circular No. 44/2017/TT-BTNMT dated October 23, 2017, issued by the Minister of Natural Resources and Environment, which stipulates technical regulations for weather radar monitoring and ozone - ultraviolet radiation.

Article 13. Responsibility for Implementation

1. The Director of the General Department of Meteorology and Hydrology shall be responsible for inspecting and guiding the implementation of this Circular.

2. Ministries, ministerial-level agencies, People's Committees of provinces and centrally governed cities, Departments of Natural Resources and Environment of provinces and centrally governed cities, and related organizations and individuals shall be responsible for implementing this Circular./.