convert_UTC_to_solartime: Convert DateTime from UTC to local solar time

In USGS-R/streamMetabolizer: Models for Estimating Aquatic Photosynthesis and Respiration

Convert DateTime from UTC to local solar time

Description

Convert DateTime from UTC to local solar time, which may be either apparent solar (perfect match between noon and solar zenith) or mean solar (exactly 24 hours between solar noons).

Usage

convert_UTC_to_solartime(
  date.time,
  longitude,
  time.type = c("apparent solar", "mean solar")
)

Arguments

date.time	date-time values in POSIXct format and UTC timezone.
longitude	numeric, in degrees, either positive and unitted ("degE" or "degW") or with sign indicating direction (positive = East)
time.type	character. "apparent solar", i.e. true solar time, is noon when the sun is at its zenith. "mean solar" approximates apparent solar time but with noons exactly 24 hours apart. Elsewhere in this package, variables named "solar.time" are mean solar time, whereas "app.solar.time" is apparent solar and "any.solar.time" is either.

Value

a POSIXct object that says it's in tz="UTC" but that's actually in solar time, with noon being very close to solar noon

References

Yard, Bennett, Mietz, Coggins, Stevens, Hueftle, and Blinn. 2005. Influence of topographic complexity on solar insolation estimates for the Colorado River, Grand Canyon, AZ. Ecological Modelling.

USGS-R/streamMetabolizer documentation built on Aug. 15, 2023, 7:50 a.m.