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Extreme climate events in some areas can affect in other areas as a result of intensive international socio-economic activity. Agains such a background, TCC/JMA provides weekly, monthly, seasonal and annual reports on extreme climate conditions worldwide.
TCC/JMA Extreme Extreme Climate Event Criteria
Extreme climate events are rarely experienced; they include massive storms, heat waves, cold spells, prolonged droughts and other phenomena with various temporal tanges, and often cause weather-related disasters that influence socio-economic activity. Statistically, TCC/JMA defines such events as phenomenona occuring once every 30 years or less. Weekly reports are based on SYNOP data submitted by National Meteorological and Hydrological Services (NMHS) around the world, while monthly, seasonal and annual reports are based on CLIMAT data from the same organizations. SYNOP reports provide real-time weather data from one specific weather stations. CLIMAT reports contain monthly statistics relating to various meteorological elements from individual weather stations for specific motnh, such as monthly mean temperature and monthly precipitation totals.
Extreme Warm/Cold Events
Extreme warm/cold events for each weather station are identified from normalized mean temperature anomalies in the target period. Anomalies are deviations from the climatological normals, and standard deviations for nomalization are based on interannual variability over the same 30 years as for climatological normals.
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Weekly
Extreme warm (cold) events are identified if weekly mean temperature anomalies from observation are estimated to exceed (or fall below) +3σ (-3σ), where σ is the standard deviation of mean temperatures in a 31-day period with the target week at its center. (e.g., If the target period is from Dec. 9th to Dec. 15th, the 31-day period is from Nov. 27th to Dec. 27th).
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Monthly
Extreme warm (cold) events are identified if monthly mean temperature anomalies from observation exceed (or fall below) +1.83σ (-1.83σ), where σ is the standard deviation of monthly mean temperatures.
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Seasonal
Extreme warm (cold) events are identified if seasonal mean temperature anomalies from observation exceed (or fall below) +1.83σ (-1.83σ), where σ is the standard deviation of seasonal mean temperatures.
Extreme Wet/Dry Events
Extreme wet/dry events for each weather station are identified from precipitation totals in the target period and thier ratio to the climatological normals.
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Weekly (Wet)
Extreme wet events are defined when weekly precipitation totals from observation exceed empirical thresholds for extreme heavy rain. Thresholds are derived from empirical approximation of extreme wet events depending on the climatological normals of precipitation totals over a 29-day period (referred to here as X) with the target week as its center (e.g., if the target period is from Dec. 9th to Dec. 15th, the 29-day period is from Nov. 28th to Dec. 26th). For example, if the X values are 10, 100, 200 and 500 mm, the corresponding thresholds are 153, 98, 81 and 59% of X, respectively. Thresholds are fixed at 59% if X exceeds 500 mm.
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Weekly (Dry)
Extreme dry events are identified if precipitatin totals from observation are lower than any value in the climatological normal base period during a 30-day period starting 29 days before the end of the target week (e.g., if the target week is from Dec. 9th to Dec. 15th, the 30-day period is from Nov. 16th to Dec. 15th).
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Monthly
Extreme wet (dry) events are identified if monthly precipitation totals from observation are more (less) than any value in the climatological normal base period for the month.
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Seasonal
Extreme wet (dry) events are identified if seasonal precipitation totals from observation are more (less) than any value in the climatological normal base period for the season.
Reports on Extreme Climate Events
TCC/JMA issued reports on worldwide extreme climate events identified using the above criteria on regular basis (weekly, monthly, seasonally and annually). Information includes the locations of such events and weather-related disasters.
| Description | Schedule |
| Weekly Report | A weekly summary of extreme climate events and weather-related disasters around the world (target period: Wednesday to Tuesday) | Every Wednesday (except national holidays) |
| Monthly Report | A monthly summary of extreme climate events and weather-related disasters around the world | Around the 14th of every month |
| Seasonal Report | A seasonal summary of extreme climate events and weather-related disasters around the world with reference to boreal seasons: winter (December to February), spring (March to May), summer (June to August) and autumn (September to November) | Around the 14th of March, June, September and December |
| Annual Report | A annual summary of extreme climate events and weather-related disasters around the world | Around the 14th of January |
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Extreme Climate Monitoring
Relevant Figures
- World Climate Charts
- Regional Map
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