Circular No. 51/2025/TT-BNNMT on technical guidelines for assessing the quality of surface meteorological data

 

CIRCULAR

TECHNICAL REGULATIONS FOR ASSESSING THE QUALITY OF SURFACE METEOROLOGICAL DOCUMENTS

On the basis of Law on Meteorology and Hydrology dated November 23, 2015;

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

Decree No. Decision No. 35/2025/NĐ-CP February 25, 2025 of the Government stipulating functions, tasks, powers, and organizational structure of the Ministry of Agriculture and Rural Development;

At the proposal of the Director of the General Meteorological Department;

The Minister of Agriculture and Rural Development issues this Circular on technical regulations for assessing the quality of surface meteorological documents.

PART I

GENERAL PROVISIONS

Article 1. Scope of Regulation

This Circular stipulates technical regulations for assessing the quality of surface meteorological observation documents recorded at meteorological stations within the national meteorological and hydrological station network.

Article 2. Applicability

This Circular applies to agencies, organizations, and individuals related to the activities of assessing the quality of surface meteorological observation documents recorded at meteorological stations within the national meteorological and hydrological station network.

Article 3. Explanation of Terms

Strategic multi-purpose hydropower plant

Surface meteorological documents are original logbooks recording information and data from observations, self-recording diagrams and reports; reports on observation activities and carriers containing observation information and data at surface meteorological stations.

Checking and controlling documents involves examining the completeness, physical condition, and form of the documents; analyzing and comparing the results of observations in the documents with standards, specifications, and technical regulations to identify errors or omissions in the observation, data collection, and information processing processes; determining the volume and capacity of the documents of surface meteorological stations.

Assessing the quality of surface meteorological documents is the activity of determining quality based on the results of checking and controlling the documents.

Spatial consistency of data refers to the logical consistency of data of one or more surface meteorological factors at the observation location compared to data from surface meteorological observations at surrounding locations.

Temporal consistency of data refers to the logical consistency of data of one or more meteorological factors compared to values of data at the same observation location during different time periods.

Consistency among observed factors refers to examining the data of surface meteorological observations between these factors at the same time and location.

Document errors refer to mistakes occurring during observation, calculation, and measurement equipment that does not meet technical standards.

Benchmark score is the highest score defined for assessing the quality of surface meteorological documents.

Deduction points are the points specified to be deducted for missing or incorrect errors.

Quality score is the difference between the benchmark score and the total deduction points.

Non-automatic surface meteorological measuring instruments (including manual measuring instruments and semi-automatic measuring instruments) are technical means for conducting measurements, transmitting, and disseminating information and data on surface meteorological factors performed by humans.

Automatic surface meteorological measuring instruments are technical means including: measuring devices and tools; devices and tools with measuring functions; systems for automatically conducting measurements of surface meteorological factors.

A non-automatic surface meteorological observation station using non-automatic measuring instruments is an observation and transmission station that conducts all or part of the surface meteorological factor observations at the station directly by observers.

An automatic surface meteorological observation station using automatic measuring instruments is an observation and transmission station that conducts all surface meteorological factor observations at the station completely automatically without human intervention.

Article 4. Principles for evaluating surface meteorological documents

1. Compliance with current technical standards, regulations, and other relevant legal documents.

2. Ensuring accuracy, objectivity, completeness, and comprehensiveness of the evaluation content.

Chapter II

TECHNICAL REGULATIONS FOR ASSESSING THE QUALITY OF SURFACE METEOROLOGICAL DOCUMENTS

Article 5. Surface meteorological documents to be evaluated

1. For non-automatic surface meteorological observation stations:

a) Daily recording books of surface meteorological elements;

b) Statistical and calculation reports of observation results;

c) Daily self-recording charts;

d) Monthly and quarterly reports on station activities, including records of regular inspection, maintenance, replacement of measuring instruments, and emergency troubleshooting at the station; special weather phenomenon reports (if any);

đ) Data files.

2. For automatic surface meteorological observation stations:

a) Data files, including: station information: station code, station name, station address, location (coordinates); station data: observation or calculated data and units of measurement of surface meteorological elements automatically transmitted daily;

b) Reports on the operation status of the automatic observation station network;

c) Records of regular inspection, maintenance, and replacement of measuring instruments; records of emergency troubleshooting at the station according to technical regulations for the operation of automatic hydro-meteorological stations.

Article 6. Content of surface meteorological document evaluation

1. Non-automatic surface meteorological observation documents:

a) Completeness of documents;

b) Physical condition and form of documents;

c) Construction works, measuring instruments;

d) Observation methods, procedures, and calibration of measuring instruments;

đ) Calculation of data, selection of characteristic values, data entry process, coding, and transmission of coded meteorological observation data;

e) Reasonableness of data in space, time, and observed factors.

2. Automatic surface meteorological observation documents:

a) Completeness of documents, including: completeness of submitted documents and automatic observation data from the station; continuity, timeliness, and accuracy of automatic observation and transmission data from the station to the receiving agency;

b) Structure and type of automatic data information;

c) Construction works, measuring instruments;

d) Calibration of measuring instruments;

đ) Reasonableness of data in space and time for one or more observed factors.

Article 7. Methods for evaluating surface meteorological documents

1. Inspection and control of surface meteorological documents.

2. Evaluation of the quality of surface meteorological documents using a scoring method based on standard points, deduction points, and quality score indices to classify them as excellent, good, average, and poor. In this regard:

a) Standard points are set at 100 points, determined for each quality assessment category; the total number of deduction points does not exceed the standard points within each assessment content;

b) Deduction points are calculated for each missing or incorrect item and are determined based on the analysis and evaluation of errors in observation, construction works, measuring instruments, and data calculation and statistics from the documents specified in Article 5 of this Circular. When assessing the quality of a factor's data where errors result from calculations based on chain errors and do not significantly affect the overall quality of the document, deduction points are counted only once;

c) The quality score (QSC) of surface meteorological documents is calculated by subtracting the total deduction points (TD) from the standard points (SP);

d) The formula for calculating the quality score of surface meteorological documents is as follows: QSC = SP – ΣTD

Article 8. Evaluation of the Quality of Surface Meteorological Documents

1. Check the quantity and specifications of surface meteorological documents in accordance with the provisions (details in Appendix I issued together with this Circular).

2. Control the quality of surface meteorological documents in accordance with the provisions (details in Appendix II issued together with this Circular).

3. Evaluate the quality of surface meteorological observation documents using non-automatic measurement instruments:

a) The standard points for evaluating the quality of surface meteorological observation documents using non-automatic measurement instruments are allocated in Table 1 as follows:

Table 1.Allocation of standard points for each category of evaluation of the quality of surface meteorological observation documents using non-automatic measurement instruments

b) Deduction points for evaluating surface meteorological observation documents using non-automatic measurement instruments are specified in Table 2 as follows:

Table 2.Deduction points for each missing or incorrect item in the quality assessment of surface meteorological observation documents using non-automatic measurement instruments

4. Evaluation of the quality of surface meteorological documents using automatic measurement instruments:

a) Standard points for each category of evaluation of the quality of surface meteorological documents using automatic measurement instruments are allocated in Table 3 as follows:

Table 3.Allocation of standard points for each category of evaluation of the quality of surface meteorological documents using automatic measurement instruments

b) Deduction points for evaluating surface meteorological documents using automatic measurement instruments are specified in Table 4 as follows:

Table 4.Deduction points for each missing or incorrect item in the quality assessment of surface meteorological documents using automatic measurement instruments

5. Scoring, summarizing results, and preparing reports on the quality assessment of surface meteorological data:

a) Prepare a report on the quality assessment of surface meteorological data observed using non-automatic measurement instruments according to the model prescribed in Appendix III attached to this Circular;

b) Prepare a report on the quality assessment of surface meteorological data observed using automatic measurement instruments according to the model prescribed in Appendix IV attached to this Circular;

c) Submit monthly reports to the unit as prescribed before the 28th day of the following month.

Article 9. Evaluation and Classification of Surface Meteorological Data Quality

1. Quality of surface meteorological data observed using non-automatic measurement instruments

The evaluation and classification of surface meteorological data observed using non-automatic measurement instruments are specified in Table 5 as follows:

Table 5:Table for evaluating and classifying the quality of surface meteorological data observed using non-automatic measurement instruments

2. Quality of surface meteorological data observed using automatic measurement instruments

The classification and evaluation of surface meteorological data observed using automatic measurement instruments are specified in Table 6 as follows:Table 6:

Chapter III

IMPLEMENTATION

Article 10. Effective Date

Below 60

This Circular takes effect from October 8, 2025.

Article 11. Transitional Provisions

Circular No. 37/2016/TT-BTNMT dated December 15, 2016 issued by the Minister of Natural Resources and Environment on technical guidelines for assessing the quality of surface meteorological data shall cease to be effective from the date this Circular takes effect, except as provided in Article 11 of this Circular.

Article 12. Responsibilities for Implementation

The Director of the National Hydro-Meteorological Service is responsible for disseminating and supervising the implementation of this Circular.

Ministries, ministerial-level agencies, provincial People's Committees, and related agencies are responsible for implementing this Circular./.

 

ANNEX I

(Issued together with Circular No. .../2025/TT-BNNMT dated .../.../2025 of the Minister of Agriculture and Rural Development)

SURFACE METEOROLOGICAL DATA QUALITY CHECK

I. Quality Check of Surface Meteorological Data Observed Using Non-Automatic Measurement Instruments

1. Receiving data and checking the submission time of the data as prescribed.

2. Checking quantity, capacity, and categorization:

a) Daily observation records of surface meteorological elements;

b) Statistical and calculation reports of observation results;

c) Daily self-recorded diagrams;

d) Monthly data files;

đ) Monthly, periodic, and ad hoc reports on observation activities of the station;

e) Maintenance and repair records of facilities, measurement instruments, and replacement parts and equipment. Check the number of copies and pages of paper documents and the number of data carriers (data files, CDs, DVDs, USBs, and other storage devices) of the documents.

3. Physical condition and format check of the documents:

a) Check if the documents are damaged, wrinkled, torn, blurred, erased;

b) Check the format of paper documents and errors in data carriers (warped, moldy, broken, virus-infected, or unable to open files on data carriers).

4. Legal and completeness check of the documents:

a) Signature of the head (or authorized person) and stamp of the providing unit;

b) Origin of materials and equipment used for observation work.

II. Quality Check of Surface Meteorological Data Observed Using Automatic Measurement Instruments

1. Receiving data and checking the submission time of the data as prescribed.

2. Checking technical reports and operations of observation stations.

3. Checking communication equipment and measurement instruments of the stations.

4. Checking the number of transmitted information and data files.

 

ANNEX II

(ISSUED TOGETHER WITH Circular number … /2025/TT-BNNMT dated ... month ... year 2025 of the Minister of Agriculture and Rural Development)

SURFACE METEOROLOGICAL DOCUMENT CONTROL

I. CONTROL OF MANUAL OBSERVATION SURFACE METEOROLOGICAL DOCUMENTS

1. PHYSICAL CONDITION, FORM AND SUBMISSION TIME OF THE DOCUMENTS:

a) Observation logbooks, humidity charts with physical damage such as tears, stains, erased data, code errors;

b) Physical condition: sun-damaged charts that do not meet fire safety thresholds;

c) Poorly written characters and numbers in logbooks and charts, making them difficult to read;

d) Submission time does not comply with regulations.

2. COMPLETENESS (DOCUMENTS, DATA), DATA TRANSMISSION:

a) Completeness of documents: complete observation logs for all measured factors and other required documents (supplementary observation logs, TYPH). Code Clim, Climmat, SYNOP;

b) Missing report forms: BCT 2 and BCT 3, BKT9;

c) Missing information and data in observation logs and charts, missing data (lost data, inaccurate data due to blurred ink, recording width > 0.5mm);

d) Missing measurement factors;

đ) Delayed data transmission;

e) Positioning records for observation sites, equipment and backups (according to reports: BCT 2,3), BKT9, supplementary observation logs TYPH.

3. QUALITY OF OBSERVATION STRUCTURES AND MEASURING EQUIPMENT BASED ON CONTENT IN REPORTS OR FIELD INSPECTIONS (IF APPLICABLE) TO DETERMINE:

a) Deterioration of observation structures: fences, columns, support frames for machines, machine shelters;

b) Failure to till soil in garden areas, ground temperature placement zones, false reporting of tilling frequency;

c) Lack of maintenance of observation structures and measuring equipment;

d) Violation of technical buffer zones affecting observation data;

đ) Maintenance of observation structures and measuring equipment not meeting technical standards (for tipping bucket rain gauges, self-recording chart recorders jumping, not adjusting zero and ten-point markers, chart markers on various machines);

e) Missing backup measuring equipment;

g) Using measuring equipment without Calibration Certificate or using equipment beyond calibration validity period;

h) Using measuring equipment and materials not conforming to technical specifications: hygrometer scale deviation, incorrect dewar, not ensuring maximum and minimum values; evaporation pan (Piche) clamps not conforming to specifications, paper diameter incompatible with pan diameter; sunshine recorder chart not meeting fire safety thresholds, hour divisions on chart > or < 60 (deviating more than 07 minutes), abnormal recording lines on chart (burn marks at both ends far from average line, unusual burn mark at 12 o'clock on chart; thermograph, hygrograph, barograph: end of chart deviating more than 1/3 of hour arc (hour arc = 15 minutes);

i) Measuring equipment installed incorrectly: tilted hygrometer stand (away from wet cloth hygrometer, water level in hygrometer cup), incorrect placement of Tx, Tn, Tg, Tgx, Tgn;

k) Sun photometer installed incorrectly: skewed burn marks, center of mirror not aligned with trough center, excess A lacking B;

l) Missing barometer (using barograph instead of barometer), do not include this measurement data;

m) Violations affecting observation data;

n) Incorrect dimensions for gardens and ground temperature measurement sites;

4. OBSERVATION METHODS:

Based on data and figures in observation logs, tables, and reports to assess the rationality of measured factor data, thereby concluding whether the observation method is correct or incorrect:

a) Compilation of incorrect observation cases: horizontal visibility; meteorological phenomena; wind direction and speed (direction, speed, characteristics); incorrect air temperature and humidity, ground temperature (usual, highest, lowest);

b) Incorrect barometer, barograph readings, incorrect station pressure, sea level pressure, incorrect three-hour pressure changes, constant correction always = 00, 01, or negative/positive two-sided;

c) Evaporation Piche readings after 07 hours always equal 00 or 01;

d) Readings after high temperature mercury bulb (Tx) always equal dry bulb temperature; readings after wet bulb temperature (Tgx) always equal ground temperature (Tg) (indicative of falsified data);

đ) Incorrect replacement and installation of various chart recorders: for thermographs, hygrographs, and barographs, incorrect time setting, not removing dirt;

e) Incorrect marking of various chart recorders, pulling charts after 07 hours and at key points, incorrect timing; replacing tipping bucket rain gauge chart during moderate to heavy rain, not measuring or noting rainfall during chart change and after major rain events (followed by intense sunlight or long time before next reading);

g) Reporting group 911 and 915 but not noting wind gusts ≥ 16m/s;

h) Errors in cloud observation (overall, low clouds): repeated observations; incorrect sequence, clouds inconsistent with meteorological phenomena, incorrect cloud quantity; incorrect observation of cloud base height inconsistent with meteorological phenomena, cloud quantity during day and night, with accompanying phenomena and without, between regions, seasons;

i) Incorrect timing for barograph readings; replacing thermograph, hygrograph, barograph charts at 07 hours;

5. DATA ENTRY, DATA CODING, DATA CALCULATION, SELECTION OF CHARACTERISTIC VALUES:

a) Incorrect entry of BKT9 report form;

b) Incorrect or missing data entry from observation logs, charts, incorrect coding (horizontal visibility, clouds, meteorological phenomena...);

c) Data coding: incomplete or incorrect coding for key points, clouds, temperature, pressure changes, dew point, meteorological phenomena;

d) Data calculation: totals, averages; incorrect table lookup for humidity, pressure, total changes, chart interpolation;

đ) Incorrect selection of characteristic values within a day, month, event;

6. SPATIAL AND TEMPORAL RATIONALITY OF DATA, BETWEEN FACTORS:

a) Spatial rationality of measured factors between automatic and manual measurements at nearby stations (similar) within the same affected area;

b) Temporal rationality: timing of meteorological phenomena and cloud appearance that could lead to those phenomena and vice versa;

c) Rationality between ground temperature and air temperature; delays due to equipment, signal distortion;

d) Rationality between observed average wind and gusts; between intensity of meteorological phenomena and indicators on charts.

II. CONTROL OF AUTOMATIC OBSERVATION SURFACE METEOROLOGICAL DOCUMENTS

Implement information and data control immediately after the observation shift ends or transmitted automatically and continuously in real-time for weather forecasting, warning, directing, and managing:

a) Control the volume of documentation according to the number of observations;

b) Controlling the data submission (transmission) time and report time;

c) Control the suitability of observed factors and meteorological characteristics;

d) Controlling to determine that the observation method is carried out correctly according to technical requirements;

d) Control the observation regime;

e) Control the rationality in space and time down to each individual observation;

g) Control the observed factors for their rationality, completeness, and reliability:

- Check the range and limits of the factors based on statistical limits;

- Check the value change steps of the factors;

- Check internal consistency;

- Check missing values and syntax check of the data bulletin;

- Comparison method to check observed and forecasted values.

 

ANNEX III

(Issued together with Circular No. .../2025/TT-BNNMT dated .../.../2025 of the Minister of Agriculture and Rural Development)

SAMPLE REPORT ON THE QUALITY ASSESSMENT RESULTS OF SURFACE METEOROLOGICAL OBSERVATION DOCUMENTS USING NON-AUTOMATIC MEASURING EQUIPMENT

 

QUALITY ASSESSMENT REPORT

SURFACE METEOROLOGICAL OBSERVATION DOCUMENTS USING NON-AUTOMATIC MEASURING EQUIPMENT

Month……year …..

1. Station name:…Station code:…

2. Assessor:…

3. Assessment unit:…

4. Quality of assessed documents:

5. Assessment results of documents:

a) Overall quality classification of documents …

b) Comments on documents...

6. Recommendation: …

 

 

ANNEX IV

(Issued together with Circular No. .../2025/TT-BNNMT dated .../.../2025 of the Minister of Agriculture and Rural Development)

SAMPLE REPORT ON THE QUALITY ASSESSMENT RESULTS OF SURFACE METEOROLOGICAL OBSERVATION DOCUMENTS USING AUTOMATIC MEASURING EQUIPMENT

 

QUALITY ASSESSMENT REPORT

SURFACE METEOROLOGICAL OBSERVATION DOCUMENTS USING AUTOMATIC MEASURING EQUIPMENT

Month……year …..

1. Station name:…Station code:…

2. Station manager, operator:…

3. Station address:…

4. Document quality:…

5. Implementing unit:…

6. Report preparer: …Position:…

Phone number: …Email: …

7. Assessment documents:

7.1. Telex data/one observation

7.2. Automatic station data/one observation

8. Quality assessment comments:…

……………………………………………………………………………………….