Percentage of Cool Nights (TN10p) — ck

ETCCDI canonical index TN10p. Percentage of days where daily Tmin falls below the 10th percentile of the calendar-day distribution from a reference period (default 1961 to 1990). Computation follows the same convention as ck_tx10p() and supports the same bootstrap argument.

Usage

ck_tn10p(
  tmin,
  dates,
  ref_start = 1961L,
  ref_end = 1990L,
  period = "annual",
  bootstrap = FALSE
)

Arguments

tmin: Numeric vector of daily minimum temperatures (degrees C).
dates: Date vector of the same length as tmax. Must contain data covering the reference period.
ref_start, ref_end: Integer. Reference period boundary years (inclusive). Defaults to 1961 and 1990.
period: Character. Aggregation period: "annual" (default) or "monthly".
bootstrap: Logical. If TRUE, apply the Zhang (2005) in-base bootstrap correction. Default FALSE for backward compatibility and speed.

Value

A data frame with columns period, value, index, and unit.

Examples

set.seed(1)
dates <- seq(as.Date("1961-01-01"), as.Date("1991-12-31"), by = "day")
tmin <- 5 + 8 * sin(2 * pi * as.integer(format(dates, "%j")) / 365) +
        rnorm(length(dates))
tail(ck_tn10p(tmin, dates))
#>        period     value index unit
#> 26 1986-01-01  8.219178 tn10p    %
#> 27 1987-01-01  9.863014 tn10p    %
#> 28 1988-01-01  7.103825 tn10p    %
#> 29 1989-01-01  9.589041 tn10p    %
#> 30 1990-01-01  7.671233 tn10p    %
#> 31 1991-01-01 12.876712 tn10p    %