Climate Extremes Indices (Re-post)

I obtained a good post (link) on the climate extremes indices. The post as follows:

Currently, the ET recommends 27 core indices (the ‘ETCCDI’ indices) that are calculated for the globe using the  RClimDex/FClimDex software.

Definitions of the 27 core indices

  • FD, Number of frost days: Annual count of days when TN (daily minimum temperature) < 0oC.Let TNijbe daily minimum temperature on day i in year j. Count the number of days where:TNij < 0oC.
  • SU, Number of summer days: Annual count of days when TX (daily maximum temperature) > 25oC.Let TXij be daily maximum temperature on day i in year j. Count the number of days where:TXij > 25oC.
  • ID, Number of icing days: Annual count of days when TX (daily maximum temperature) < 0oC.Let TXijbe daily maximum temperature on day i in year j. Count the number of days where:TXij < 0oC.
  • TR, Number of tropical nights: Annual count of days when TN (daily minimum temperature) > 20oC.Let TNijbe daily minimum temperature on day i in year j. Count the number of days where:TNij > 20oC.
  • GSL, Growing season length: Annual (1st Jan to 31st Dec in Northern Hemisphere (NH), 1st July to 30th June in Southern Hemisphere (SH)) count between first span of at least 6 days with daily mean temperature TG>5oC and first span after July 1st (Jan 1st in SH) of 6 days with TG<5oC.Let TGij be daily mean temperature on day i in year j. Count the number of days between the first occurrence of at least 6 consecutive days with:TGij > 5oC.and the first occurrence after 1st July (1st Jan. in SH) of at least 6 consecutive days with:TGij < 5oC.
  • TXx, Monthly maximum value of daily maximum temperature:Let TXx be the daily maximum temperatures in month k, period j. The maximum daily maximum temperature each month is then:TXxkj=max(TXxkj)
  • TNx, Monthly maximum value of daily minimum temperature:Let TNx be the daily minimum temperatures in month k, period j. The maximum daily minimum temperature each month is then:TNxkj=max(TNxkj)
  • TXn, Monthly minimum value of daily maximum temperature:Let TXn be the daily maximum temperatures in month k, period j. The minimum daily maximum temperature each month is then:TXnkj=min(TXnkj)
  • TNn, Monthly minimum value of daily minimum temperature:Let TNn be the daily minimum temperatures in month k, period j. The minimum daily minimum temperature each month is then:TNnkj=min(TNnkj)
  • TN10p, Percentage of days when TN < 10th percentile :Let TNij be the daily minimum temperature on day i in period j and let TNin10 be the calendar day 10th percentile centred on a 5-day window for the base period 1961-1990. The percentage of time for the base period is determined where:TNij < TNin10To avoid possible inhomogeneity across the in-base and out-base periods, the calculation for the base period (1961-1990) requires the use of a bootstrap procedure. Details are described in Zhang et al. (2005).
  • TX10p, Percentage of days when TX < 10th percentile :Let TXij be the daily maximum temperature on day i in period j and let TXin10 be the calendar day 10th percentile centred on a 5-day window for the base period 1961-1990. The percentage of time for the base period is determined where:TXij < TXin10To avoid possible inhomogeneity across the in-base and out-base periods, the calculation for the base period (1961-1990) requires the use of a bootstrap procedure. Details are described in Zhang et al. (2005).
  • TN90p, Percentage of days when TN > 90th percentile :Let TNij be the daily minimum temperature on day i in period j and let TNin90 be the calendar day 90th percentile centred on a 5-day window for the base period 1961-1990. The percentage of time for the base period is determined where:TNij > TNin90To avoid possible inhomogeneity across the in-base and out-base periods, the calculation for the base period (1961-1990) requires the use of a bootstrap procedure. Details are described in Zhang et al. (2005).
  • TX90p, Percentage of days when TX > 90th percentile :Let TXij be the daily maximum temperature on day i in period j and let TXin90 be the calendar day 90th percentile centred on a 5-day window for the base period 1961-1990. The percentage of time for the base period is determined where:TXij > TXin90To avoid possible inhomogeneity across the in-base and out-base periods, the calculation for the base period (1961-1990) requires the use of a bootstrap procedure. Details are described in Zhang et al. (2005).
  • WSDI, Warm spell duration index: Annual count of days with at least 6 consecutive days when TX > 90th percentileLet TXij be the daily maximum temperature on day i in period j and let TXin90 be the calendar day 90th percentile centred on a 5-day window for the base period 1961-1990. Then the number of days per period is summed where in intervals of at least 6 consecutive days:TXij > TXin90
  • CSDI, Cold spell duration index: Annual count of days with at least 6 consecutive days when TN < 10th percentileLet TNij be the daily maximum temperature on day i in period j and let TNin10 be the calendar day 10th percentile centred on a 5-day window for the base period 1961-1990. Then the number of days per period is summed where, in intervals of at least 6 consecutive days:TNij < TNin10
  • DTR, Daily temperature range: Monthly mean difference between TX and TNLet TXij and TNij be the daily maximum and minimum temperature respectively on day i in period j. If I represents the number of days in j, then:

  • Rx1day, Monthly maximum 1-day precipitation:Let RRij be the daily precipitation amount on day i in period j. The maximum 1-day value for period j are:Rx1dayj = max (RRij)
  • Rx5day, Monthly maximum consecutive 5-day precipitation:Let RRkj be the precipitation amount for the 5-day interval ending k, period j. Then maximum 5-day values for period j are:Rx5dayj = max (RRkj)
  • SDII, Simple precipitation intensity index: Let RRwj be the daily precipitation amount on wet days, w (RR ≥ 1mm) in period j. If W represents number of wet days in j, then:

  • R10mm, Annual count of days when PRCP≥ 10mm: Let RRij be the daily precipitation amount on day i in period j. Count the number of days where:RRij ≥ 10mm
  • R20mm, Annual count of days when PRCP≥ 20mm: Let RRij be the daily precipitation amount on day i in period j. Count the number of days where:RRij ≥ 20mm
  • Rnnmm, Annual count of days when PRCP≥ nnmm, nn is a user defined threshold: Let RRij be the daily precipitation amount on day i in period j. Count the number of days where:RRij ≥ nnmm
  • CDD, Maximum length of dry spell, maximum number of consecutive days with RR < 1mm: Let RRij be the daily precipitation amount on day iin period j. Count the largest number of consecutive days where:RRij < 1mm
  • CWD, Maximum length of wet spell, maximum number of consecutive days with RR ≥ 1mm: Let RRij be the daily precipitation amount on day iin period j. Count the largest number of consecutive days where:RRij ≥ 1mm
  • R95pTOT, Annual total PRCP when RR > 95p. Let RRwj be the daily precipitation amount on a wet day w (RR ≥ 1.0mm) in period i and letRRwn95 be the 95th percentile of precipitation on wet days in the 1961-1990 period. If W represents the number of wet days in the period, then:

  • R99pTOT, Annual total PRCP when RR > 99p: Let RRwj be the daily precipitation amount on a wet day w (RR ≥ 1.0mm) in period i and letRRwn99 be the 99th percentile of precipitation on wet days in the 1961-1990 period. If W represents the number of wet days in the period, then:

  • PRCPTOT, Annual total precipitation in wet days: Let RRij be the daily precipitation amount on day i in period j. If I represents the number of days in j, then

References

  1. Karl, T.R., N. Nicholls, and A. Ghazi, 1999: CLIVAR/GCOS/WMO workshop on indices and indicators for climate extremes: Workshop summary. Climatic Change, 42, 3-7.
  2. Peterson, T.C., and Coauthors: Report on the Activities of the Working Group on Climate Change Detection and Related Rapporteurs 1998-2001. WMO, Rep. WCDMP-47, WMO-TD 1071, Geneve, Switzerland, 143pp. (Available as: wgccd.2001.pdf)
  3. Zhang, X., et al. (2005): Avoiding Inhomogeneity in Percentile-Based Indices of Temperature Extremes. J. Climate, 18, 1641-1651. (Available as: JCLI3366.1.pdf)

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