calc_daily_evap | R Documentation |
This function calculates daily radiation, condensation, and evaporation fluxes.
calc_daily_evap( lat, n, elv = 0, y = 0, sf = 1, tc = 23, sw = 1, ke = 0.0167, keps = 23.44, komega = 283, kw = 0.26 )
lat |
double, decimal degrees. |
n |
double, day of year. |
elv |
double, elevation, m A.S.L. Default: 0. |
y |
double, year. Default: 0. |
sf |
double, fraction of sunshine hours. Default: 1. |
tc |
double, mean daily air temperature, degrees C. Default: 23.0. |
sw |
double, evaporative supply rate, mm/hr. Default: 1.0. |
ke |
double, eccentricity of earth's orbit. Default: 0.01670, 2000CE (Berger, 1978). |
keps |
double, obliquity of earth's elliptic. Default: 23.44, 2000CE (Berger, 1978). |
komega |
double, lon. of perihelion, degrees Default: 283, 2000CE (Berger, 1978). |
kw |
double, PET entrainment, (1 + kw) * EET Default: 0.26 (Priestley-Taylor, 1972) |
Returns a list
object with the following variables:
nu_deg ............ true anomaly, degrees
lambda_deg ........ true longitude, degrees
dr ................ distance factor, unitless
delta_deg ......... declination angle, degrees
hs_deg ............ sunset angle, degrees
ra_j.m2 ........... daily extraterrestrial radiation, J/m^2
tau ............... atmospheric transmittivity, unitless
ppfd_mol.m2 ....... daily photosyn photon flux density, mol/m^2
hn_deg ............ net radiation hour angle, degrees
rn_j.m2 ........... daily net radiation, J/m^2
rnn_j.m2 .......... daily nighttime net radiation, J/m^2
econ_m3.j ......... water to energy conversion, m^3/J
cond_mm ........... daily condensation, mm
eet_mm ............ daily equilibrium evapotranspiration, mm
pet_mm ............ daily potential evapotranspiration, mm
hi_deg ............ intersection hour angle, degrees
aet_mm ............ daily actual evapotranspiration, mm
Berger, A.L., 1978. Long-term variations of daily insolation and Quaternary climatic changes. Journal of Atmospheric Sciences, 35(12), pp.2362-2367. doi: 10.1175/1520-0469(1978)035<2362:LTVODI>2.0.CO;2
Priestley, C.H.B. and Taylor, R.J., 1972. On the assessment of surface heat flux and evaporation using large-scale parameters. Monthly weather review, 100(2), pp.81-92. doi: 10.1175/1520-0493(1972)100<0081:OTAOSH>2.3.CO;2
evap <- splash::calc_daily_evap(lat = 37.7, n = 172, elv = 142, y = 2000, sf = 1, tc = 23.0, sw = 0.9) cat(sprintf("Evaporation values:\n")) cat(sprintf(" s: %0.6f Pa/K\n", evap$s_pa.k)) cat(sprintf(" Lv: %0.6f MJ/kg\n", (1e-6) * evap$lv_j.kg)) cat(sprintf(" Patm: %0.6f bar\n", (1e-5) * evap$patm_pa)) cat(sprintf(" pw: %0.6f kg/m^3\n", evap$pw_kg.m3)) cat(sprintf(" gamma: %0.6f Pa/K\n", evap$gam_pa.k)) cat(sprintf(" Econ: %0.6f mm^3/J\n", (1e9) * evap$econ_m3.j)) cat(sprintf(" Cn: %0.6f mm\n", evap$cond_mm)) cat(sprintf(" rx: %0.6f\n", evap$rx)) cat(sprintf(" hi: %0.6f degrees\n", evap$hi_deg)) cat(sprintf(" EET: %0.6f mm\n", evap$eet_mm)) cat(sprintf(" PET: %0.6f mm\n", evap$pet_mm)) cat(sprintf(" AET: %0.6f mm\n", evap$aet_mm))
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