# galvez_davison_index#

metpy.calc.galvez_davison_index(pressure, temperature, mixing_ratio, surface_pressure, vertical_dim=0)[source]#

Calculate GDI from the pressure, temperature, mixing ratio, and surface pressure.

Calculation of the GDI relies on temperatures and mixing ratios at 950, 850, 700, and 500 hPa. These four levels define three layers: A) Boundary, B) Trade Wind Inversion (TWI), C) Mid-Troposphere.

GDI formula derived from [Galvez2015]:

$GDI = CBI + MWI + II + TC$

where:

• $$CBI$$ is the Column Buoyancy Index

• $$MWI$$ is the Mid-tropospheric Warming Index

• $$II$$ is the Inversion Index

• $$TC$$ is the Terrain Correction [optional]

GDI Values & Corresponding Convective Regimes#

GDI Value

Expected Convective Regime

>=45

35 to 45

Scattered thunderstorms and/or scattered to widespread rain showers.

25 to 35

Isolated to scattered thunderstorms and/or scattered showers.

15 to 25

Isolated thunderstorms and/or isolated to scattered showers.

5 to 10

Isolated to scattered showers.

<5

Strong TWI likely, light rain possible.

Parameters:
Returns:

pint.Quantity – GDI Index

Examples

>>> from metpy.calc import mixing_ratio_from_relative_humidity
>>> 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 mixing ratio
>>> mixrat = mixing_ratio_from_relative_humidity(p, T, rh)
>>> galvez_davison_index(p, T, mixrat, p[0])
<Quantity(-8.78797532, 'dimensionless')>


## Examples using metpy.calc.galvez_davison_index#

Sounding Calculation Examples

Sounding Calculation Examples