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Equal-weighted monthly climatology from CMIP6 / CCAM point files

Source: R/extract_climate_point.R
climate_point_monthly_climatology.Rd

Companion to extract_climate_point(), for building the monthly delta-change factors of scenario_workflow. extract_climate_point() merges variables onto a shared Date and, to do that safely, averages together any model-days a fixed-length calendar's month-end clamp maps onto the same real date (see its documentation) - which very slightly down-weights those clamped days in a monthly mean taken from its output, since they then count as a single row instead of several. This function instead reads each variable's own per-file series independently and averages straight by calendar month, before any Date-based merge or clamp-collapse happens, so every model day counts equally regardless of how many (or how few) real dates it lands on.

Usage

climate_point_monthly_climatology(
  path,
  lon,
  lat,
  vars = c("MET_tmpair", "MET_pprain", "MET_wndspd", "MET_radswd", "MET_humrel",
    "MET_radlwd", "MET_prsttn"),
  experiments = NULL,
  method = c("bilinear", "nearest"),
  calendar = c("auto", "365_day", "360_day", "366_day", "standard"),
  years = NULL,
  fun = mean,
  verbose = TRUE
)

Arguments

path

directory holding the .nc files, or a character vector of file paths.

lon, lat

point of interest, decimal degrees (WGS84).

vars

variables to return, as AEME MET_* names or CMIP short names (do not mix the two). Default is the seven mapped variables; only those present on disk are returned.

experiments

optional character vector to keep (e.g. c("historical", "ssp245")); NULL (default) returns every experiment found.

method

"bilinear" (default) interpolation between the four surrounding grid nodes, or "nearest" grid node.

calendar

"auto" (default, read from the time variable's calendar attribute), or force one of "365_day", "360_day", "366_day", "standard". A 365_day / 360_day series is mapped onto real dates, so it has no 29 February (and, for 360_day, no 31st).

years

optional integer vector of calendar years (as decoded onto real dates) to include, e.g. a historical or future reference window. NULL (default) uses every year found.

fun

the averaging function applied per experiment/variable/month. Default mean.

verbose

print each file as it is read.

Value

a data frame with experiment, variable (AEME MET_* name), month (integer 1:12) and value.

See also

extract_climate_point(), scenario_workflow

Examples

if (FALSE) { # \dontrun{
clim <- climate_point_monthly_climatology("inst/extdata/rotorua_cmip6",
                                        lon = 176.2717, lat = -38.0790,
                                        years = 2005:2014)
} # }