#' @importFrom tibble tibble
NULL

#' Ozone Depleting Gas Index Data, 1992-2022
#'
#' The NOAA Earth System Research Laboratory has an "ozone depleting gas index"
#'  (ODGI) data set from 1992 to 2018. This dataset summarizes Table 1 and Table 2 from its website.
#'  The primary interest here (for my purposes) is the ODGI indices
#'  (including the new 2012 measure). The data set includes constituent greenhouse
#'  gases/chlorines as well in parts per trillion. The primary use here is for
#'  in-class illustration.
#'
#' @format A data frame with 62 observations on the following 16 variables.
#' \describe{
#' \item{\code{year}}{the year}
#' \item{\code{cat}}{categorical variable for the Antarctic or Mid-Latitudes measurements}
#' \item{\code{cfc12}}{CFC-12 concentration in parts per trillion}
#' \item{\code{cfc11}}{CFC-11 concentration in parts per trillion}
#' \item{\code{ch3cl}}{chloromethane concentration in parts per trillion}
#' \item{\code{ch3br}}{bromomethane concentration in parts per trillion}
#' \item{\code{ccl4}}{carbon tetrachloride concentration in parts per trillion}
#' \item{\code{ch3ccl3}}{methyl chloroform concentration in parts per trillion}
#' \item{\code{halons}}{aggregate concentration in parts per trillion of H-1211, H-1301 and H-2402}
#' \item{\code{cfc113}}{trichlorotrifluoroethane concentration in parts per trillion}
#' \item{\code{hcfcs}}{aggregate concentration in parts per trillion of HCFC-22, HCFC-141b, and HCFC-142b}
#' \item{\code{wmo_minor}}{aggregate concentration in parts per trillion of CFC-114, CFC-115, halon 2402 and halon 1201}
#' \item{\code{sum}}{the sum of all greenhouse gas concentration measurements}
#' \item{\code{eesc}}{includes consideration of lag times for transport and mixing associated with transport. New as of 2012}
#' \item{\code{odgi_old}}{old greenhouse gas index, no longer supported as of 2012}
#' \item{\code{odgi_new}}{new greenhouse gas index, as of 2012}
#' }
#'
#' @source \url{https://gml.noaa.gov/odgi/}
#'
"ODGI"