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Outline of Weekly, 10-day and Half-monthly Mean Temperatures and Total Precipitation


     Figures for weekly, 10-day and half-monthly mean temperatures and total precipitation are obtained using data from SYNOP messages received via GTS from WMO Members around the world. The methods used to calculate mean temperatures and total precipitation are described below.
     Figures on normal temperatures and precipitation other than those for Japanese stations are estimated based on interpolation of the monthly normal for the period 1981 – 2010. Those for Japanese stations are calculated from the daily normal for the same period.

Note: This analysis is based on preliminary and unchecked data.

Mean temperature

     SYNOP messages provide real-time temperature data every six hours. Daily mean temperatures are calculated by averaging four real-time temperatures (at 00, 06, 12 and 18UTC) for the day, and are estimated as an average of the daily maximum and daily minimum temperatures when fewer than four SYNOP messages are received for the day. Mean temperatures are calculated by averaging the daily mean when at least 80% of daily values are available.
     Time-series graphs of 10-day and half-monthly temperatures are provided for stations selected by JMA.

Total precipitation

     SYNOP messages provide precipitation data for the latest 6-, 12- and 24-hour periods, and daily precipitation is calculated by simply adding these totals. Total precipitation values are calculated by adding together daily precipitation data when at least 80% of daily values are available.
     Time-series graphs of 10-day and half-monthly total precipitation are provided for stations selected by JMA.


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