lifted_index#
- metpy.calc.lifted_index(pressure, temperature, parcel_profile, vertical_dim=0)#
Calculate Lifted Index from the pressure temperature and parcel profile.
Lifted index formula derived from [Galway1956] and referenced by [DoswellSchultz2006]:
\[LI = T500 - Tp500\]where:
\(T500\) is the measured temperature at 500 hPa
\(Tp500\) is the temperature of the lifted parcel at 500 hPa
Calculation of the lifted index is defined as the temperature difference between the observed 500 hPa temperature and the temperature of a parcel lifted from the surface to 500 hPa.
- Parameters
pressure (
pint.Quantity
) – Atmospheric pressure level(s) of interest, in order from highest to lowest pressuretemperature (
pint.Quantity
) – Atmospheric temperature corresponding to pressureparcel_profile (
pint.Quantity
) – Temperature profile of the parcelvertical_dim (int, optional) – The axis corresponding to vertical, defaults to 0. Automatically determined from xarray DataArray arguments.
- Returns
pint.Quantity
– Lifted Index
Examples
>>> from metpy.calc import dewpoint_from_relative_humidity, lifted_index, parcel_profile >>> from metpy.units import units >>> # pressure >>> p = [1008., 1000., 950., 900., 850., 800., 750., 700., 650., 600., ... 550., 500., 450., 400., 350., 300., 250., 200., ... 175., 150., 125., 100., 80., 70., 60., 50., ... 40., 30., 25., 20.] * units.hPa >>> # temperature >>> T = [29.3, 28.1, 23.5, 20.9, 18.4, 15.9, 13.1, 10.1, 6.7, 3.1, ... -0.5, -4.5, -9.0, -14.8, -21.5, -29.7, -40.0, -52.4, ... -59.2, -66.5, -74.1, -78.5, -76.0, -71.6, -66.7, -61.3, ... -56.3, -51.7, -50.7, -47.5] * units.degC >>> # relative humidity >>> rh = [.85, .65, .36, .39, .82, .72, .75, .86, .65, .22, .52, ... .66, .64, .20, .05, .75, .76, .45, .25, .48, .76, .88, ... .56, .88, .39, .67, .15, .04, .94, .35] * units.dimensionless >>> # calculate dewpoint >>> Td = dewpoint_from_relative_humidity(T, rh) >>> # compute the parcel temperatures from surface parcel >>> prof = parcel_profile(p, T[0], Td[0]) >>> # calculate the LI >>> lifted_index(p, T, prof) <Quantity([-7.42560365], 'delta_degree_Celsius')>