Example ecmwfr

ecmwfr_temperature.R

library(ecmwfr)

wf_set_key(service = "webapi")

request <- list(
  class   = "ei",
  dataset = "interim",
  expver  = "1",
  date    = "19790101",
  grid    = "0.75/0.75",
  levtype = "sfc",
  param   = "167.128",
  stream  = "moda",
  type    = "an",
  target  = "monthly_temp.nc",
  format  = "netcdf")

sfc_temps <- wf_archetype(request, c("date", "grid"))


format_dates <- function(dates) {
  paste0(lubridate::year(dates),
         formatC(lubridate::month(dates), width = 2, flag = "0"),
         formatC(lubridate::day(dates), width = 2, flag = "0"),
         collapse = "/")
}

dates <- seq.Date(as.Date("1988-08-01"), as.Date("2018-08-01"), "1 year")


wf_request(request = sfc_temps(date = dates, grid = "3/3"), 
           user = "eliocampitelli@gmail.com", 
           transfer = TRUE,
           path = ".")

library(metR)
library(ggplot2)
library(data.table)
library(magrittr)

temperature <- ReadNetCDF("monthly_temp.nc")
setnames(temperature, c("longitude", "latitude"), c("lon", "lat"))

ggplot(temperature[time == time[1]], aes(lon, lat)) +
  geom_contour_fill(aes(z = t2m)) +
  scale_fill_divergent(midpoint = 273)


trends <- temperature[, FitLm(year = year(time), t2m, se = TRUE), 
                      by = .(lon, lat)] 
trends[, p.value :=  pt(abs(estimate)/std.error, df, lower.tail = FALSE)]

ggplot(trends[term == "year"], aes(lon, lat)) +
  geom_contour_fill(aes(z = estimate*10)) +
  stat_subset(aes(subset = p.value <= 0.01), 
              geom = "point", size = 0.1, alpha = 0.5) +
  scale_fill_divergent()

gmt <- temperature[, .(t2m = weighted.mean(t2m, cos(lat*pi/180))), by = year(time)]

ggplot(gmt, aes(year, t2m)) +
  geom_line() +
  geom_smooth(method = "lm")

trend <- lm(t2m ~ year, data = gmt)

coef(trend)[2]*10