mars: Mars Solar Radiation

# Equation 19 (1990): Beam hourly insolation on Mars horizontal surface [Wh/m2].
#
# 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 V. - HOURLY AND DAILY BEAM INSOLATION ON A HORIZONTAL SURFACE AT MARS SURFACE.

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

test_that("I_bh.", {

  # Tolerance.
  tolerance = 10

  # Expected data.
  expected_results = list(
    # Areocentric Longitude.
    "69" = cbind(
      0.65, # Optical depth tau factor.
      c(252, 230, 186, 128, 67, 20, 3) # Expected hourly I_bh from 12:00 to 19:00.
    ),
    "120" = cbind(
      0.40,
      c(352, 322, 265, 190, 103, 33, 2)
    ),
    "153" = cbind(
      0.50,
      c(345, 310, 244, 163, 77, 15, 0)
    ),
    "249" = cbind(
      1.40,
      c(69, 50, 26, 10, 2, 0, 0)
    ),
    "299" = cbind(
      3.25,
      c(3, 2, 1, 0, 0, 0, 0)
    ))

  # Test input parameter
  phi = 22.3

  expected_result_index = 1
  for(expected_result in expected_results){
    Ls = strtoi(names(expected_results[expected_result_index]))
    tau = expected_result[1,1]

    hour_index = 1
    for(Ts_start in 12:18){

      # Expected output.
      Ibh_expected = expected_result[hour_index, 2]

      # Calculated output.
      Ibh = I_bh(Ls=Ls, phi=phi, tau=tau, Ts_start=Ts_start, Ts_end=Ts_start+1)

      # Test assertion
      expect_equal(Ibh, Ibh_expected, tolerance=tolerance, scale=1)

      hour_index = hour_index + 1
    }

    expected_result_index = expected_result_index + 1
  }
})