Retrieves globally averaged marine surface methane monthly mean data from National Oceanic and Atmospheric Administration. The Global Monitoring Division of NOAA’s Earth System Research Laboratory has measured methane since 1983 at a globally distributed network of air sampling sites. A global average is constructed by first smoothing the data for each site as a function of time, and then smoothed values for each site are plotted as a function of latitude. Global means are calculated from the latitude plot at each time step. https://gml.noaa.gov/ccgg/trends_ch4/ https://gml.noaa.gov/ccgg/about/global_means.html
Usage
get_methane(use_cache = TRUE, write_cache = getOption("hs_write_cache"))Arguments
- use_cache
(boolean) Return cached data if available, defaults to TRUE. Use FALSE to fetch updated data.
- write_cache
(boolean) Write data to cache, defaults to FALSE. Use TRUE to write data to cache for later use. Can also be set using options(hs_write_cache=TRUE)
Details
get_methane invisibly returns a tibble with NOAA's monthly globally averaged methane measurement.
The returned object includes year, month, date, average, average uncertainty, trend, and trend uncertainty columns.
Trend is NOAA's published trend. Please refer to above website for details. CH4 expressed as a mole fraction in dry air, nanomol/mol, abbreviated as ppb.
References
Lan, X., K.W. Thoning, and E.J. Dlugokencky: Trends in globally-averaged CH4, N2O, and SF6 determined from NOAA Global Monitoring Laboratory measurements. Version 2022-11, doi:10.15138/P8XG-AA10
Author
Hernando Cortina, hch@alum.mit.edu
Examples
# \donttest{
# Fetch from cache if available, otherwise download:
ch4 <- get_methane()
#
# Force fetch from source:
ch4 <- get_methane(use_cache=FALSE)
#
# Review cache contents and last update dates:
hockeystick_cache_details()
#> <hockeystick cached files>
#> directory: /home/runner/.cache/R/hockeystick
#>
#
# Plot output using package's built-in ggplot2 settings
plot_methane(ch4) # }
