Introduction
Hector uses DOECLIM, a diffusion ocean-energy balance, to calculate mean global air temperature from sea-surface and land-surface temperature anomalies. DOECLIM can simulate the different rates of warming over land and ocean surfaces, meaning that the land-ocean warming ratio is an emergent property of Hector. However, users do have the option to provide a land-ocean warming ratio to be used in place of DOECLIM’s internal calculations. This capability enables Hector to emulate the land-ocean warming dynamics of specific Earth System Models.
The purpose of this vignette is to demonstrate how providing a user-defined land-ocean warming ratio can affect Hector output. ## Setup
library(ggplot2)
library(hector)
library(magrittr)
theme_set(theme_bw(base_size = 14))
Run default Hector
Complete a default run of Hector, one that uses DOECLIM to calculate land and ocean air temperature.
years_to_keep <- 1850:2100
vars_to_keep <- c(GLOBAL_TEMP(), LAND_AIR_TEMP(), OCEAN_AIR_TEMP(), ATMOSPHERIC_CO2())
inifile <- file.path(system.file('input', package = 'hector'), 'hector_ssp245.ini')
core <- newcore(inifile)
run(core, max(years_to_keep))
#> Hector core: Unnamed Hector core
#> Start date: 1745
#> End date: 2300
#> Current date: 2100
#> Input file: /Library/Frameworks/R.framework/Versions/4.1/Resources/library/hector/input/hector_ssp245.ini
out1 <- fetchvars(core, years_to_keep, vars_to_keep)
out1$scenario <- "default"
out1$variable <- paste0(gsub(out1$variable, pattern = "_", replacement = " "), " (", out1$units, ")")
ggplot(data = out1) +
geom_line(aes(year, value)) +
facet_wrap("variable", scales = "free") +
labs(title = "Default Hector",
subtitle = "ssp245",
x = NULL) +
theme(axis.text.x = element_text(angle = 90))
Run Hector with different land ocean warming ratios
Start by writing a function to help us set the land ocean warming ratio, run hector, and fetch some results.
# Helper function that runs a Hector core with a new land-ocean warming ratio.
#
# Args
# hc: an active Hector core
# value: the land ocean warming ratio to use
# Return: data frame of Hector results
run_with_lo <- function(hc, value){
# Set the land ocean warming ratio.
setvar(hc, NA, LO_WARMING_RATIO(), value, getunits(LO_WARMING_RATIO()))
# Run Hector
run(hc)
# Fetch and format the output.
out <- fetchvars(hc, years_to_keep, vars_to_keep)
out$scenario <- value
out$variable <- paste0(gsub(out$variable, pattern = "_", replacement = " "), " (", out$units, ")")
return(out)
}
# Make a vector of the land ocean warming ratios to test out.
lo_to_use <- seq(from = 1, to = 2.5, length.out = 20)
# Apply our helper function to the various land ocean warming ratio values & concatenate the results into a single data frame.
lapply(lo_to_use, run_with_lo, hc = core) %>%
do.call(what = "rbind") ->
hector_lo_results
Plot the results
ggplot(data = hector_lo_results) +
geom_line(aes(year, value, color = scenario, group = scenario)) +
facet_wrap("variable", scales = "free") +
labs(title = "User provided land-ocean warming ratio",
subtitle = "ssp245",
x = NULL,
y = NULL) +
theme(axis.text.x = element_text(angle = 90)) +
guides(color=guide_legend(title = "lo ratio"))
Compare default Hector with user provided land ocean warming ratio
ggplot() +
geom_line(data = hector_lo_results, aes(year, value, color = scenario, group = scenario)) +
geom_line(data = out1, aes(year, value), color = "orange", size = 1) +
facet_wrap("variable", scales = "free") +
labs(title = "User provided land-ocean warming ratio",
subtitle = "ssp245",
x = NULL,
y = NULL) +
theme(axis.text.x = element_text(angle = 90)) +
guides(color=guide_legend(title = "lo ratio"))
