Standardise meteorological variable names and units for AEME

Attempts to match column names in a meteorological data frame to AEME standard variable names using guess_aeme_vars(), then detects the likely input units of each variable from its values and converts to the units expected by the package.

Usage

standardise_met(
  met,
  verbose = TRUE,
  precip_accum = TRUE,
  tz = "UTC",
  longitude = NULL
)

Arguments

met

data.frame; meteorological data with a Date column and one or more meteorological variable columns.

verbose

logical; if TRUE (default), emit cli_inform messages describing each detected unit conversion applied. Set to FALSE for quiet operation inside pipelines.

precip_accum

logical; how to interpret MET_pprain / MET_ppsnow when the data is sub-daily. TRUE (default) treats them as the depth accumulated within each step (the ERA5 / AWS convention) and rescales to the mm/day rate the rest of AEME expects; FALSE takes the values to be a mm/day rate already and leaves them untouched. Ignored for daily data, where the two are identical.

tz

character; Olson timezone in which a naive/character Date column is expressed. Sub-daily timestamps are converted to UTC; daily data is treated as calendar dates and never shifted. A column that already carries a timezone (including "UTC") is taken at face value here – reinterpreting a "UTC"-tagged column against a declared local zone happens once, upstream, in add_met / aeme_constructor. Default "UTC"; build_aeme passes the object's time$tz.

longitude

numeric; lake longitude in decimal degrees (east positive). When supplied and the data is sub-daily, the hour at which MET_radswd peaks each day is compared against astronomical solar noon for that longitude; a warning is emitted if they differ by more than 3 h, which usually means the timestamps are in local time rather than UTC. NULL (default) skips the check. build_aeme passes the lake longitude.

Value

The input data frame with column names remapped to AEME standard names and values converted to AEME standard units where a conversion was necessary. Columns that could not be matched are retained unchanged with a warning. A warning is also emitted if any required variable (MET_radswd, MET_tmpair, MET_wndspd, MET_pprain) is absent after renaming.

AEME standard variables and units

Variable	Name	Unit	Required
Shortwave radiation	MET_radswd	W/m²	Yes
Air temperature	MET_tmpair	°C	Yes
Wind speed	MET_wndspd	m/s	Yes
Rainfall	MET_pprain	mm/day	Yes
Snowfall	MET_ppsnow	mm/day	No (defaults to 0)
u wind component	MET_wnduvu	m/s	No (derivable)
v wind component	MET_wnduvv	m/s	No (derivable)
Sea-level pressure	MET_prmslp	Pa	No (derivable)
Station pressure	MET_prsttn	Pa	No (derivable)
Cloud cover	MET_cldcvr	1 (fraction)	No (derivable)
Longwave radiation	MET_radlwd	W/m²	No (derivable)
Dew point temp.	MET_tmpdew	°C	No (derivable)
Vapour pressure	MET_prvapr	hPa	No (derivable)
Relative humidity	MET_humrel	\ Wind direction	MET_wnddir