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QX/T 370-2017 in English

QX/T 370-2017 in English

VALID

Identification method for El Ni?o/La Ni?a events

  • Issued on:2017-02-10
  • Implemented on:2017-03-15
  • File Format:PDF
  • Delivery:Via email within 1~3 business days
Price(USD): $380.00
$369.00
Standard No: QX/T 370-2017
Document status: VALID
Title in English: Identification method for El Ni?o/La Ni?a events
Title in Chinese: 厄尔尼诺/拉尼娜事件判别方法
Language: English
File Format: Electronic (PDF)
Delivery: Via email within 1~3 business days
Issued on: 2017-02-10
Implemented on: 2017-03-15
ICS Classification: 07.060-Geology. Meteorology. Hydrology
Chinese Classification: A47-Meteorology
Professional Classification: QX-Meteorology
Related Topics: event
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Introduction

Background and significance of the standard

QX/T 370-2017 is the first unified El Niño/La Niña event discrimination standard in my country's meteorological industry, compiled by the National Climate Center and a number of climate experts. The introduction of this standard fills the domestic regulatory gap in this field. Its technical points include:

  • Using the NINO3.4 area Sea Surface Temperature Anomaly (SSTA) as the core indicator
  • Clearly define the event intensity level (weak/moderate/strong/super strong)
  • For the first time, distinguish between eastern type and central type events

Core discrimination indicator system

Index name Monitoring area Calculation formula Discrimination threshold
NINO3.4 index 170°W-120°W,5°S-5°N Regional SSTA average ≥0.5℃(El Nino)≤-0.5℃(La Nina)
Eastern Type Index NINO3 Area TNINO3-αTNINO4 Continued ≥3 months and ≥0.5℃
Central Type Index NINO4 Area TNINO4-βTNINO3 Continued ≥3 months and ≥0.5℃

Event characteristic quantification standard

Intensity classification standard

The peak intensity of the 3-month moving average NINO3.4 index is used as the basis for judgment:

  • Weak event: 0.5-1.3℃ (equivalent to 1.5 times the standard deviation)
  • Moderate event: 1.3-2.0℃
  • Strong event: 2.0-2.5℃
  • Super strong event: ≥2.5℃ (such as the 1997/1998 event)

Duration requirement

The threshold must be met for 5 consecutive months or more, among which:

  1. Starting month: the month when the standard is first met
  2. End month: the last month that meets the standard
  3. Total number of months: the cumulative value between the start and end months

Analysis of historical event characteristics

Appendix A of the standard provides detailed statistics of 35 typical events from 1950 to 2016:

  • Super El Niño: events in 1982/83, 1997/98, and 2015/16
  • Longest La Niña: lasted 24 months in 1998/2000
  • Type change: the event changed from central type to eastern type in 2009/10

Business application suggestions

  1. Data source selection: HadISST data was used before 1982, and OIv2 data is recommended thereafter
  2. Real-time monitoring: 3-month sliding average should be calculated to eliminate seasonal fluctuations
  3. Type determination: Both the eastern and central types need to be calculated
  4. Intensity prediction: Refer to the development patterns of similar historical events

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