Mixed Layer Lifted Index (LI)

Usage

Lifted_index_ml(ta_s, hus_s, pa_s, ta_pl, hus_pl, pa_pl, dp = 50, nthreads = 1)

Arguments

ta_s: Parcel temperature [lon, lat, time] at 2 meter above the surface (K).
hus_s: Parcel specific humidity [lon, lat, time] at 2 meter above the surface (kg/kg).
pa_s: Surface pressure [lon, lat, time] (hPa).
ta_pl: air temperature [lon, lat, lev, time] on pressure level (K).
hus_pl: specific humidity [lon, lat, lev, time] on pressure level (kg/kg).
pa_pl: pressure profile [lev] in descending manner (hPa).
dp: Thickness of the mixed layer (hPa). Default is 50 hpa.
nthreads: an integer specifying the number of threads to use for computation (OpenMP). Default is 1.

Value

The dp mixed layer lifted index [lon, lat, time] (k).

Details

The Lifted Index (LI) is calculated by lifting a mixed-layer parcel pseudo-adiabatically to 500 hPa and comparing its temperature to the environmental temperature at that level.

References

Galway, J.G., 1956. The lifted index as a predictor of latent instability. Bull. Am. Meteorol. Soc. 37, 528–529.
Haklander, A. J., & Van Delden, A. (2003). Thunderstorm predictors and their forecast skill for the Netherlands. Atmospheric Research, 67–68, 273–299. doi:10.1016/S0169-8095(03)00056-5 .

Examples

data("ERA5_sfc")
ta_s <- ERA5_sfc$t2m
td_s <- ERA5_sfc$t2d
pa_s <- ERA5_sfc$sp / 100
hus_s <- hus_from_td(td_s, pa_s)
dim(hus_s) <- dim(ta_s)

data("ERA5_pl")
ta <- ERA5_pl$ta
hus <- ERA5_pl$hus
# convert to hPa
pa <- ERA5_pl$plev / 100
res <- Lifted_index_ml(ta_s,
  hus_s,
  pa_s,
  ta,
  hus,
  pa,
  dp = 50
)