QX/T 759-2025 in English

Standard Overview and Technical Background

QX/T759-2025, "Quality Control of Meteorological Observation Data - Sea Surface," is an industry standard developed by the China Meteorological Administration for quality control of ocean surface observation data. It will be officially implemented in June 2025. This standard fills a gap in standardization in my country's marine meteorological observation data quality control field and provides a technical basis for ensuring data quality from observation platforms such as ships, buoys, and ocean stations.

With the rapid development of marine meteorological observation technology, my country has established a three-dimensional observation network covering both nearshore and offshore waters. However, the complexity of the marine environment, the diversity of observation platforms, and the real-time requirements for data transmission have placed higher standards on observation data quality control. QX/T759-2025 was developed based on advanced international experience and combined with the actual practice of marine meteorological observation in my country to establish a scientific and comprehensive quality control system.

Classification and Analysis of Quality Control Objects

The standard clearly divides sea surface observation data into three categories of quality control objects, each of which has unique observation characteristics and quality control requirements:

In-depth Analysis of Nine Quality Control Methods

5.1 Basic Information Verification

Basic information verification is the first line of defense for quality control, covering verification of core information such as observation time, location, and platform identification:

• Observation Time Verification: Utilizes strict numerical range verification to ensure the rationality and integrity of time data
• Observation Location Verification: Enhances location data accuracy through dual verification of latitude and longitude and the Marsden ID
• Platform Identification Standardization: Format verification of various platform identifications is performed in accordance with international and domestic standards

5.2 Land and Ocean Location Verification

Utilizes global ocean and land location background data to identify unusual inland observation locations and prevent land observation data from being mistakenly included in ocean datasets.

5.3 Missing Observation Verification

The system identifies missing data and terminates the subsequent verification process, improving processing efficiency and avoiding invalid calculations.

5.4 Limit value check

Appendix A of the standard specifies in detail the limit value range of each factor, such as the air pressure range of 870-1070hPa, the temperature range of -49.1-50℃, etc. Data outside the range will be directly judged as erroneous data.

5.5 Check on the main range of changes

For elements with obvious latitudinal distribution characteristics, such as air temperature and sea surface temperature, a combination of latitude zone check and climate threshold check is adopted:

5.6 Internal consistency check

The rationality of the data is verified by the physical relationship between the elements. Appendix C of the standard provides detailed criteria for 9 tables:

• Air pressure consistency: Verification of the logical relationship between the 3-hour pressure change and the air pressure tendency
• Temperature-humidity relationship: The basic physical principle that the dew point temperature shall not be higher than the air temperature
• Wind element association: Reasonable range of wind direction and speed, maximum wind speed and instantaneous wind speed
• Weather phenomenon coordination: Physical matching check of temperature and precipitation type

5.7 Temporal consistency check

Includes two dimensions: rigid value check and variability check, to ensure the rationality of data in time series:

5.8 Extreme Value Time Check

Verify the rationality of the extreme value occurrence time. The 1-hour extreme value should be within 1 hour before the current time, and the 24-hour extreme value should be within 24 hours before the current time.

5.9 Data Quality Identification

Use the quality control code system of the QX/T118-2020 standard to achieve standardized identification of quality status.

Quality Control Process Architecture

Chapter 6 of the standard establishes a complete real-time quality control process, forming a progressive quality screening system:

1. Data input: Receive raw observation data
2. Basic information check: Verify basic information such as time and location
3. Land and sea location check: Confirm that the observation location is in the ocean area
4. Missing data check: Identify and process missing data
5. Boundary value check: Verify that the data is within a reasonable physical range
6. Main change range check: Verify the rationality of data based on latitude characteristics
7. Internal consistency check: Verify the physical relationship between elements
8. Temporal consistency check: Verify the rationality of the data time series
9. Extreme value time check: Verify the rationality of the extreme value occurrence time
10. Data Quality Identification: Outputs data with quality identification.

Technological Evolution and Standard Innovation

QX/T759-2025 achieves several key technical innovations:

Multi-dimensional Quality Control System

The standard establishes a comprehensive quality control system covering basic information, specialized elements, spatial relationships, and time series, significantly improving data quality reliability compared to traditional single-source quality control methods.

Marine Feature Coverage

For the first time, typical marine elements such as waves, currents, and sea ice are systematically included in the quality control scope, and specialized quality control criteria are established, such as verifying the logical relationships between various wave height parameters.

Platform-Specific Processing

Differentiated quality control strategies are developed based on the characteristics of different observation platforms, such as ships, buoys, and oceanographic stations, such as checking ship speed and verifying the position consistency of fixed stations.

Implementation Suggestions and Application Guidance

System Construction Suggestions

It is recommended that all marine meteorological observation data receiving and processing units establish or upgrade the quality control system in accordance with the standard requirements:

• Configure a global ocean and land position background database to support ocean and land position inspection
• Establish a climate threshold parameter library for each latitude zone to support the inspection of major change ranges
• Develop a multi-factor association analysis module to implement internal consistency inspection
• Build a time series analysis engine to support temporal consistency inspection

Quality control strategy optimization

According to different application scenarios, the quality control links can be appropriately adjusted:

Staff training and standard promotion

It is recommended to organize and carry out standard promotion training. The key training content should include:

• In-depth understanding of the technical requirements of the standard
• Key Points for Implementing Each Quality Control Method
• Correct Interpretation of Quality Control Results
• Processing Process for Abnormal Data

Expected Benefits of Standard Implementation

The implementation of QX/T759-2025 will produce significant technical and business benefits:

• Improve data quality: Through systematic quality control, the risk of using erroneous data will be significantly reduced
• Promote data sharing: Unified quality standards provide a technical basis for international and domestic data exchange
• Support accurate forecasts: High-quality observation data provide reliable initial fields for numerical weather forecasts
• Serve the marine economy: Reliable marine meteorological data provide decision-making support for shipping, fisheries, offshore engineering, etc.

The release and implementation of this standard marks that my country's marine meteorological observation data quality management has entered a new stage of standardization and normalization, and will provide solid technical support for the construction of a strong maritime nation.