NEWS.md

In climatekit: Unified Climate Indices for Temperature, Precipitation, and Drought

climatekit 0.2.0

Bug fixes

• ck_total_precip() now applies the canonical 'ETCCDI' 'PRCPTOT' wet-day filter (precipitation >= 1 mm) by default. Pass wet_day_threshold = 0 to recover the previous raw-sum behaviour.
• ck_first_frost() and ck_last_frost() gain a lat argument and use hemisphere-appropriate cutoffs. Southern Hemisphere users no longer get silent NA results.
• ck_branas() gains a lat argument; Southern Hemisphere growing season is now October-February of the following year.
• ck_precip_intensity() (SDII) returns NA for periods with no valid observations rather than NaN.

In-base bootstrap (Zhang 2005)

• ck_tx10p(), ck_tn10p(), ck_tx90p(), ck_tn90p() gain a bootstrap = FALSE argument. When TRUE, the leave-one-out resampling of Zhang et al. (2005) is applied to remove self-inclusion bias for analysis years inside the reference period. This is the canonical 'climdex.pcic' / 'climpact' behaviour and is required for climate-change attribution work spanning the base period.

ET-SCI heatwave family extensions

• ck_hwm(), ck_hwa(), ck_cwm(), ck_cwa() gain a mode = c( "excess", "absolute") argument. "excess" (default) preserves the existing 'ET-SCI' / 'climpact' convention. "absolute" returns mean / peak raw temperature on event days, matching Perkins-Alexander (2013).
• New function ck_ehf() implements the Excess Heat Factor of Nairn and Fawcett (2013), the Australian Bureau of Meteorology operational heatwave metric. Three annual statistics are exposed via stat = c("max", "n_positive", "sum_positive").

SPI / SPEI distribution choice

• ck_spi() gains distribution = c("gamma", "pearsonIII"). Pearson III is preferred in arid regions where the wet-day distribution is highly skewed (Stagge et al. 2015).
• ck_spei() gains distribution = c("log-logistic", "gev"). GEV is fitted via Hosking (1985) L-moments.

FAO-56 Penman-Monteith reference ET

• New function ck_pet_pm() implements the FAO-56 Penman-Monteith reference evapotranspiration (Allen et al. 1998), the international standard. Optional inputs include relative humidity, wind speed, incoming solar radiation, and elevation; FAO-56 fallbacks are used where these are unavailable. ck_pet() remains as the simpler temperature-only Hargreaves estimator.

ETCCDI canonical 27 coverage

• Added 13 new functions completing the full canonical 'ETCCDI' 27 set: ck_txx(), ck_tnx(), ck_txn(), ck_tnn() (extreme values); ck_tx10p(), ck_tn10p(), ck_tx90p(), ck_tn90p(), ck_r95p(), ck_r99p() (calendar-day percentile base, default reference period 1961-1990); ck_wsdi(), ck_csdi() (proper calendar-day spell duration). ck_growing_season() was already ETCCDI-compliant.
• ck_warm_spell() is retained as a quick series-quantile approximation; its documentation now points to ck_wsdi() for the canonical ETCCDI definition.

ET-SCI heatwave and cold-wave families

• Added 10 new functions implementing the 'ET-SCI' heatwave and cold-wave families on a calendar-day percentile base. Heatwave family: ck_hwn(), ck_hwf(), ck_hwd(), ck_hwm(), ck_hwa() (number, frequency, duration, magnitude, amplitude). Cold-wave duals: ck_cwn(), ck_cwf(), ck_cwd(), ck_cwm(), ck_cwa().
• The 'CWD' acronym is used by both 'ETCCDI' (Consecutive Wet Days) and 'ET-SCI' (Cold Wave Duration). ck_cwd() here is the ET-SCI cold-wave version; ck_wet_days() is the ETCCDI precipitation index. Both function-level documentation pages cross-reference the other.

Discovery surfaces

• ck_etccdi_27() returns the canonical 27 'ETCCDI' indices as a data frame with code, name, variable, unit, definition, ck_function, and status columns. Use it to audit coverage or to locate the function for a given short code.
• ck_catalogue() returns the full implementation catalogue (51 rows). ck_browse(sector, standard, search) filters by sector ('agriculture', 'health', 'water', 'energy'), standard ('ETCCDI', 'ET-SCI', 'agroclimatic', etc.), or free-text search.

Gridded support

• ck_apply_grid(x, fun, dates, ...) applies any ck_* function over the cells of a 'terra' 'SpatRaster' and returns a SpatRaster with one layer per output period.
• ck_from_netcdf(path, var) is a thin convenience wrapper around terra::rast() for 'netCDF' inputs with file-existence and argument validation.
• 'terra' and 'ncdf4' are in 'Suggests'; loading climatekit alone does not pull them in.

Documentation

• inst/CITATION provides 'bibentry' records for the package and for Alexander et al. (2006) and Zhang et al. (2011).
• 'CITATION.cff' at the repository root supports GitHub's citation widget.
• New vignette climdex-migration documents the function-name crosswalk from 'climdex.pcic' to climatekit, plus interface-shift notes (numeric-vector inputs, tidy data-frame outputs, default reference period).

Documented limitations

• The percentile-based indices use the standard ±2-day calendar window but do not implement the Zhang et al. (2005) in-base bootstrap. Years inside the reference period therefore have a small self-inclusion bias. This is documented in each function's documentation page.

climatekit 0.1.0

• Initial release.
• 10 temperature indices: frost days, ice days, summer days, tropical nights, growing season length, heating/cooling/growing degree days, diurnal temperature range, warm spell duration.
• 8 precipitation indices: consecutive dry/wet days, total precipitation, heavy/very heavy precipitation days, max 1-day and 5-day precipitation, precipitation intensity (SDII).
• 3 drought indices: Standardized Precipitation Index (SPI), Standardized Precipitation-Evapotranspiration Index (SPEI), potential evapotranspiration (Hargreaves method).
• 5 agroclimatic indices: Huglin, Winkler, Branas, first/last frost dates.
• 4 comfort indices: wind chill, heat index, humidex, fire danger index.
• Generic dispatcher ck_compute() for programmatic index selection.
• ck_available() and ck_metadata() for index discovery.
• ck_convert_temp() for temperature unit conversion.

climatekit documentation built on May 9, 2026, 5:08 p.m.