QX/T 413-2018 in English

Interpretation of the core content of the standard

This standard innovatively establishes a six-level evaluation system based on the Air Pollution Meteorological Index. Through the dynamic coupling calculation of the Calm Weather Index (S) and Pollutant Concentration (O), it achieves a quantitative assessment of the impact of meteorological conditions on pollution diffusion.

Technical specifications for grade classification

Analysis of Key Technical Elements

Mixing Layer Height Calculation

The boundary layer thickness is determined using the potential temperature gradient method. The top of the mixing layer is determined when the vertical rate of change of potential temperature is ≤0.005K/m. This parameter directly affects the vertical diffusion space of pollutants.

Calm Weather Index Algorithm

This algorithm is a weighted summation of the sub-indices of 10 key meteorological factors, with the 10-meter wind speed and vertical velocity having the highest weight coefficients (accounting for approximately 35% of the total impact).

Recommendations for the implementation of the standard

1. Data quality control: The spatiotemporal consistency of ground observation station and sounding data must be ensured
2. Local calibration: The a₁ and a₂ coefficients should be refitted with the latest data annually
3. Warning linkage: The pollution emergency response mechanism should be activated when the index reaches Level 4

Technology Evolution Analysis

Compared to GB/T34299-2017, the innovations of this standard are:
1. Introducing the dynamic weight coefficient mechanism (a₂)
2. Adding high-altitude elements (700hPa divergence) as a calculation factor
3. Using the percentile interval method to eliminate the influence of extreme values