Data Service / Atlas of Taiwan Climate Change Key Indices
AR5 Statistical Downscaling Edition Hydrological Indices AR6 Statistical Downscaling Edition
Table 1 Climate change key indices used in this atlas
Temperature indices Precipitation indices
DTR RR1
TX90p PRCPTOP
TN90p SDII
TX10p R10mm
TN10p R20mm
TXx R80mm
TNx R200mm
TXn Rx1day
TNn Rx5day
HWDI CDD
CWDI CWD

Definitions of the indices for precipitation

  1. RR1, Wet days (units: days)
    Annual count of days when daily precipitation ≥ 1mm
  2. PRCPTOT, Annual total precipitation in wet days (units: mm)
  3. SDII, Simple daily precipitation intensity index (units: mm/day)
    Annual total precipitation in wet days divided by the number of wet days
  4. R10mm, Annual count of days when daily precipitation is greater than or equal to 10mm (units: days)
  5. R20mm, Annual count of days when daily precipitation is greater than or equal to 20mm (units: days)
  6. R80mm, Annual count of days when daily precipitation is greater than or equal to 80mm (units: days)
  7. R200mm, Annual count of days when daily precipitation is greater than or equal to 200mm (units: days)
  8. Rx1day, Annual Maximum 1‐day precipitation (units: mm)
  9. Rx5day, Annual maximum consecutive 5‐day precipitation (units: mm)
  10. CDD, Annual maximum number of consecutive dry days (units: days)
    Annual maximum number of consecutive days with daily precipitation < 1mm
  11. CWD, Annual maximum number of consecutive wet days (units: days)
    Annual maximum number of consecutive days with daily precipitation ≥ 1mm

Definitions of the indices for temperature

  1. DTR, Daily temperature range (units: °C)
    Annual mean difference between daily maximum temperature (TX) and daily minimum temperature (TN)
  2. TX90p, Annual count of days when TX > 90th percentile (units: days)
    Annual count of days when daily maximum temperature exceeds the 90th percentile of maximum temperature during a 5-day window centred on each calendar day of the baseline period 1995-2014. To avoid possible inhomogeneity across the in-base and out-base periods, the calculation for the baseline period (1995-2014) requires the use of a bootstrap processure. Details are described in Zhang et al. (2005).
  3. TN90p, Annual count of days when TN > 90th percentile (units: days)
    Annual count of days when daily minimum temperature exceeds the 90th percentile of minimum temperature during a 5-day window centred on each calendar day of the baseline period 1995-2014. To avoid possible inhomogeneity across the in-base and out-base periods, the calculation for the baseline period (1995-2014) requires the use of a bootstrap processure. Details are described in Zhang et al. (2005).
  4. TX10p, Annual count of days when TX < 10th percentile (units: days)
    Annual count of days when daily maximum temperature is below the 10th percentile of maximum temperature during a 5-day window centred on each calendar day of the baseline period 1995-2014. To avoid possible inhomogeneity across the in-base and out-base periods, the calculation for the baseline period (1995-2014) requires the use of a bootstrap processure. Details are described in Zhang et al. (2005).
  5. TN10p, Annual count of days when TN < 10th percentile (units: days)
    Annual count of days when daily minimum temperature is below the 10th percentile of minimum temperature during a 5-day window centred on each calendar day of the baseline period 1995-2014. To avoid possible inhomogeneity across the in-base and out-base periods, the calculation for the baseline period (1995-2014) requires the use of a bootstrap processure. Details are described in Zhang et al. (2005).
  6. TXx, Annual maximum value of daily maximum temperature (units: °C)
  7. TNx, Annual maximum value of daily minimum temperature (units: °C)
  8. TXn, Annual minimum value of daily maximum temperature (units: °C)
  9. TNn, Annual minimum value of daily minimum temperature (units: °C)
  10. HWDI, Heat wave duration index (units: days)
    Annual count of days with at least 3 consecutive days when TX > 95th percentile of the baseline period 1995-2014
    Note: The original definition of heatwave (the daily maximum temperature of more than five consecutive days exceeds the average maximum temperature by 5 °C) does not apply to the climate system in Taiwan, so it has been revised to be defined as daily maximum temperature with at least 3 consecutive days exceeds the 95th percentile during the baseline period (1995-2014).
  11. CWDI, Cold wave duration index (units: days)
    Annual count of days with at least 3 consecutive days when TN < 5th percentile of the baseline period 1995-2014
    Note: In Taiwan, a cold wave is defined as the minimum temperature at Taipei Station being below 10°C. However, the original definition (the daily minimum temperature of more than five consecutive days is below the average minimum temperature by 5 °C) does not align with the commonly used definition in Taiwan, therefore it has been revised to be defined as daily minimum temperature with at least 3 consecutive days is below the 5th percentile during the baseline period (1995-2014).