GB/T 21983-2020.Warm winter grades.
1 Scope
GB/T 21983 specifies the determination method and grade classification of warm winter at a single station, region and the whole country.
GB/T 21983 is applicable to the monitoring, prediction, evaluation and service of warm winter.
2 Terms and definitions
The following terms and definitions apply to this document.
2.1
Winter mean air temperature
The average temperature from December of the previous year to February of the current year (target year).
Note: The unit is degrees Celsius (℃).
[GB/T 33675-2017, Definition 2.1]
2.2
Climatological normal
Climatological state
Annual value
The average value of meteorological elements in the last three consecutive full decades.
Note: According to the relevant regulations of the World Meteorological Organization (WMO), it is updated once every decade, that is, during the period from 2011 to 2020, the average value from 1981 to 2010 is used as its climatological average value, and so on.
2.3
Winter mean surface air temperature anomaly
The difference between the winter mean temperature and its climatological average.
Note: The unit is degrees Celsius (℃).
2.4
Warm winter
Climatological phenomenon in which the winter mean temperature is higher than the climatological average to a certain extent.
2.5
weather station
A meteorological observation station, also called a station or site.
[GB/T 33675-2017, definition 2.4]
2.6
region
A given geographical area.
Note 1: Such as administrative area, climate zone, river basin area, etc., not including the entire country.
Note 2: Rewrite GB/T 33675-2017, definition 2.5.
2.7
threshold of warm winter for weather station
The critical value for determining the warm winter and its degree at a single station.
2.8
warm winter index
A quantity that describes the warm winter and its degree.
2.9
Valid station
A meteorological observation station with a continuous temperature observation record of more than 30 years.
2.10
Valid grid
The national area is divided into grids according to the given latitude and longitude grid intervals, and the grid contains valid stations.
Note: Rewrite GB/T 33675-2017. Definition 2.7.
This standard specifies the determination method and grade classification of warm winter for a single station, region, and the whole country. This standard applies to the monitoring, prediction, evaluation and service of warm winter.

ICS07.060
National Standard of the People's Republic of China
GB/T21983—2020
Replaces GB/T21983—2008
Warm winter grade
Warm winter grades
2020-07-21Release
State Administration for Market Regulation
National Standardization Administration
2020-07-21Implementation
GB/T21983—2020
Terms and definitions
Classification, determination and grading of warm winter
Appendix A (Normative Appendix)
Appendix B (Normative Appendix)
References…·
Method for selecting warm winter readings
Calculation method for national warm winter index
This standard was drafted in accordance with the rules given in GB/T1.1-2009. GB/T21983—2020
This standard replaces GB/T21983—2008 "Warm Winter Grades". Compared with GB/T21983-2008, in addition to editorial changes, the main technical changes are as follows:
Modified the "Scope" chapter (see Chapter 1, Chapter 1 of the 2008 edition); Modified the definitions of "warm winter", "single-station warm winter threshold", "winter hand average temperature" and "climate average" (see Chapter 2, 2.1~2.4 of the 2008 edition)
Added the terms and definitions of "single station", "region", "warm winter index", "effective station" and "effective grid" (see 2.5, 2.6, 2.8~2.10); Added "warm winter classification" (see 3.1); Modified the definition method of regional strong warm winter and national strong warm winter (see 3.2.2.2, 3. 3.2.2, 3.2.2 and 3.3.2 of the 2008 edition); - Added requirements for regional warm winter assessment sites (see 3.2.2.3); Added explanations on the scope of calculation of the national warm winter index (see 3.2.3.3); Added provisions for the selection of the target year climate average (see A.1 of Appendix A): - Added anomaly calculation formula (see A.4 of Appendix A); - Modified the grid spacing of longitude and latitude grid division and the calculation formula of effective grid area (see B.1 of Appendix B, 3.3.1.1 and 3.3.1.2 of the 2008 edition);
Added the calculation method of the national strong warm winter index (see B.6 and B.7 of Appendix B). This standard is proposed by the China Meteorological Administration.
This standard is under the jurisdiction of the National Technical Committee for Climate and Climate Change Standardization (SAC/TC540). Drafting unit of this standard: National Climate Center. The main drafters of this standard are Chen Yu, Xiang Yang, Zou Xukai and Wang Ling. The previous versions of the standard replaced by this standard are: GB/T21983-2008.
1 Scope
Warm winter level
This standard specifies the determination method and level classification of warm winter at a single station, region and the whole country. This standard is applicable to the monitoring, prediction, evaluation and service of warm winter. Terms and definitions
The following terms and definitions apply to this document
Winter mean air temperature
The average temperature from December of the previous year to February of the current year (target year), Note: The unit is degrees Celsius (℃).
[GB/T33675—2017, Definition 2.1]
Climatological average
climatological normal
Climatological state
Annual value
The average value of meteorological elements in the last three consecutive full decades GB/T21983—2020
Note: In accordance with the relevant regulations of the World Meteorological Organization (WMO), it is updated once every decade, that is, during the period of 2011-2020, the average value of 1981-2010 is adopted as its climatological average, and so on. 2.3
Winter average temperature anomaly
wintermean surface air temperature anomaly The difference between the winter average temperature and its climatological average Note: The unit is degrees Celsius (℃).
warmwinter
A climate phenomenon in which the average temperature in winter is higher than the climate average by a certain degree2.5
weatherstation
A meteorological observation station, also known as a station or site［GB/T33675—2017 definition 2.4］
region
A given geographical range.
Note 1: Such as administrative regions, climate regions, river basins, etc., not including the entire country. Note 2: Rewrite GB/T33675—2017, definition 2.5.2.7
Threshold of warm winter for weather station
Threshold of warm winter for weather station The critical value for determining the warm winter and its degree at a single station. 1
GB/T21983—2020
Warm winter index
warmwinterindex
A quantity that describes a warm winter and its degree
Valid stationvalidstation
A meteorological observation station with a continuous temperature observation record of more than 30 years2.10
Valid grid
validgrid
The national area is divided into grids according to the given longitude and latitude grid spacing, including grids with valid stationsNote: Rewritten GB/T33675—2017, definition 2.7, 3 Classification, judgment and grade classification of warm winter
Classification of warm winter
Warm winter is divided into single-station warm winter, regional warm winter and national warm winter. 3.2
Determination and classification
3.2.1 Single-station warm winter
3.2.1.1 If the single-station winter average temperature anomaly (△T) is greater than or equal to the single-station warm winter value, it is determined to be a single-station warm winter. The method for determining the single-station warm winter threshold is shown in A.5 of Appendix A.
Single-station warm winter is divided into single-station weak warm winter and single-station strong warm winter. The classification, index and threshold are shown in Table 1. 3.2.1.2
Table 1 Classification of single-station warm winter
Class name
Weak warm winter at single station
Strong warm winter at single station
AT calculation see formula (A.3), 6 (standard deviation) calculation see formula (A.2) 3.2.2 Regional warm winter
Grade index and reading value
0.430≤AT<1.290
AT≥1.29
3.2.2.1 If the ratio of the number of warm winter stations in the region to the total number of valid stations is greater than or equal to 50%, it is judged as a regional warm winter 3.2.2.2
Regional warm winter is divided into regional strong warm winter and regional weak warm winter. In the regional warm winter year, if the ratio of the number of strong warm winter stations in the region to the total number of valid stations is greater than or equal to 25%, it is judged as a regional strong warm winter, otherwise it is judged as a regional weak warm winter. 3.2.2.3 All valid stations within the region should participate in the regional warm winter determination. 3.2.3 National warm winter
If the national warm winter index is greater than or equal to 50%, it is determined to be a national warm winter. The calculation of the national warm winter index is shown in B.1~3.2.3.1 in Appendix B.
3.2.3.2 The national warm winter is divided into a national strong warm winter and a national weak warm winter. In a national warm winter year, if the national strong warm winter index is greater than or equal to 25%, it is determined to be a national strong warm winter, otherwise it is determined to be a national weak warm winter. The calculation of the national strong warm winter index is shown in B.6~B.7. 3.2.3.3 The calculation of the national warm winter index does not include Taiwan Province, Hong Kong Special Administrative Region, and Macao Special Administrative Region 2
A.1 Selection of target year climate statistics
Appendix A
(Normative Appendix)
Method for selecting warm winter threshold values
GB/T21983—2020wwW.bzxz.Net
The target year climate average and standard deviation are calculated using the last 30 years closest to the target year. The selection of the years is specified in Table A.1. Table A.1
Calculation of climate average values ​​corresponding to target years Target year
Climate average values ​​Selected years
1991-2000
1961-1990
Climate average values ​​Calculation formula
Climate average values ​​are calculated as shown in formula (A.1):
Where:
2001-20102011-202021-20301971-2000
1981-20101991-2020-Climate average values ​​of winter average temperature, in degrees Celsius (℃); year number, i=1, 2, …, 30;
Winter average temperature of the ith year, in degrees Celsius (℃). T
A.3 Standard Deviation Calculation Formula
Standard deviation calculation is shown in formula (A.2):
Where:
Standard deviation of winter average temperature.
A.4 Anomaly Calculation Formula
Anomaly calculation is shown in formula (A.3):
Where:
S(T,-T)2
AT=TT
...........
Anomaly of winter average temperature in target year, in degrees Celsius (℃); Winter average temperature in target year, in degrees Celsius (℃). A.5 Single-station warm winter threshold
And so on
And so on
..(A.1)
..(A.2)
......( A.3)
Using the ternary method, the winter average temperature sequence arranged from high to low is divided into three equal parts: warm, normal, and cold, with a probability of 3
GB/T21983—2020
33.3% probability corresponding to the warm threshold is 0.43c, which is used as the single-station warm winter threshold; the warm threshold corresponding to the 10% probability is 1.29g, which is used as the single-station strong warm winter threshold.
B.1 Effective grid area
The effective grid area is calculated as shown in formula (B.1): Where:
Appendix B
(Normative Appendix)
Calculation method of national warm winter index
GS,=S.Xcosp
Area of ​​a single effective grid in non-equatorial regions, in square kilometers (km\); GB/T21983—2020
Approximate area of ​​a 1.0°×1.0° grid in the equatorial region (S.=110.0×111.0), in square kilometers (km2); latitude of the center point of the effective grid, in degrees (); effective grid serial number.
National effective area
National effective area is calculated as shown in formula (B.2): ES
Where:
National effective area, unit is square kilometer (km\); Total number of effective grids
Effective grid warm winter area
Effective grid warm winter area is calculated as shown in formula (B.3): SnC
Where:
GWS, =AC, ×GS,
Effective grid warm winter area, unit is square kilometer (km\); Warm winter area weight coefficient is the ratio of the number of warm winter stations in the effective grid to the total number of stations. B.4
National warm winter area
National warm winter area is calculated as shown in formula (B.4): WS
Where:
National warm winter area, unit is square kilometer (km2): Effective grid warm winter area, unit is square kilometer (km2). .(B.2)
..(B.4)
GB/T21983—2020
National warm winter index
The calculation of the national warm winter index WI is shown in formula (B.5): B.6
National strong warm winter area
×100%
The national strong warm winter area is calculated according to formula (B.4). Among them, the effective grid strong warm winter area is calculated according to formula (B.3). B.7
National strong warm winter index
The national strong warm winter index is the ratio of the national strong warm winter area to the national effective area SnG
...(B.5)
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