mars: Mars Solar Radiation

# Global daily insolation on Mars horizontal surface [Wh/m2-day].
#
# Based on equations presented in the following publication:
#   Appelbaum, Joseph & Flood, Dennis. (1990). Solar radiation on Mars. Solar Energy. 45. 353–363. 10.1016/0038-092X(90)90156-7. 
#   https://ntrs.nasa.gov/?R=19890018252
#
# Expected results taken from:
#   TABLE IV. - HOURLY AND DAILY GLOBAL INSOLATION ON A HORIZONTAL SURFACE AT MARS SURFACE.
#   TABLE V. Daily insolation on a horizontal surface (Update 1990).
context("Global daily insolation on Mars horizontal surface")
source("utils.R")

# Disable warnings.
Sys.setenv(NET_FLUX_FUNCTION_SHOW_WARNINGS = FALSE)

# Test with expected results from TABLE IV.
test_that("H_h: Global daily insolation on a horizontal surface", {
  tolerance = 25

  phi = 22.3
  al = 0.1

  expected_results = list(
    "69" = c(0.65, 3340),
    "120" = c(0.40, 3860),
    "153" = c(0.50, 3882),
    "249" = c(1.40, 1900))
    # FIXME: Larger errors when Ls = 299°.
    #"299" = c(3.25, 1024))

  index = 1
  for(er in expected_results){

    Ls = strtoi(names(expected_results)[index])
    tau = er[1]
    Hh_expected = er[2]

    Hh = H_h(Ls=Ls, phi=phi, tau=tau, al=al)
    expect_equal(Hh, Hh_expected, tolerance=tolerance, scale=1)

    index = index + 1
  }
})

test_that("H_h: Global daily insolation on a horizontal surface at VL1", {
  # 3.2% Error tolerance.
  tol = 0.032

  # Test input parameter.
  Ls_seq = seq(0, 355, 5)
  al = 0.1

  # Run the tests.
  test_daily_insolation_on_horizontal_surface(
    spacecraft = "VL1",
    field = "Hh",
    tolerance = tol,
    Ls_seq = Ls_seq,
    al = al,
    verbose = FALSE)

})

test_that("H_h: Global daily insolation on a horizontal surface at VL2", {
  # 3.8% Error tolerance.
  tol = 0.038

  # Test input parameter.
  Ls_seq = seq(0, 355, 5)
  al = 0.1

  # Run the tests.
  test_daily_insolation_on_horizontal_surface(
    spacecraft = "VL2",
    field = "Hh",
    tolerance = tol,
    Ls_seq = Ls_seq,
    al = al,
    verbose = FALSE)

})