tidync-co2.R

#url <- "https://dap.tern.org.au/thredds/ncss/ecosystem_process/ozflux/AdelaideRiver/2022_v2/L5/default/AdelaideRiver_L5_20071017_20090524.nc"

library(tidync)
library(lubridate)
library(dplyr)
url <- "https://dap.tern.org.au/thredds/dodsC/ecosystem_process/ozflux/AdelaideRiver/2022_v2/L5/default/AdelaideRiver_L5_20071017_20090524.nc"

# peek at metadata for time units
nc_atts(url) |> filter(variable=="time") |> mutate(value = unlist(value))

decimal_day <- function(time) {
  as.POSIXct.numeric(time*60*60*24,
                     tz="UTC", 
                     origin = as.POSIXct("1800-01-01"))
}
x <- tidync(url)
y <- activate(x, "D1,D0,D3") |> 
  hyper_tibble(select_var =c("CO2", "Ta", "RH", "Ts")) |>
  mutate(datetime = decimal_day(time))

## for L3 data, NAs coded as negatives
y |> 
  filter(CO2 > 0) |> 
  ggplot(aes(datetime, CO2)) + geom_point(shape="+", alpha=.1)