User:Supportstorm/Pressure Equation

Knaff & Zehr (2007):

x=23.286-0.483(Vsrm)-((Vsrm/24.254)^2)-12.587(S)-0.483(lat)+Penv

Vsrm=Vmax-(1.5(c)^0.63)

S=(((r34/9)-3)/(Vmax(((66.785-0.09102(Vmax)+1.0619(lat-25))/500)^(0.1147+0.0055(Vmax)-0.001(lat-25))))

Courtney & Knaff (2009):

x=5.962-0.267(Vsrm)-((Vsrm/18.26)^2)-6.80(S)+Penv, lat < 18

x=23.286-0.483(Vsrm)-((Vsrm/24.254)^2)-12.587(S)-0.483(lat)+Penv, lat > 18

Vsrm=Vmax-(1.5(c)^0.63)

S=(((r34/9)-3)/(Vmax(((66.785-0.09102(Vmax)+1.0619(lat-25))/500)^(0.1147+0.0055(Vmax)-0.001(lat-25))))


 * S cannot go under 0.4 or the reading will be incorrect. This includes tropical lows and small systems. (Note: This rarely happens if using a global analysis grid)


 * If Vsrm winds are below 20 knots use the wind listed in best track. (Note: Nullified if 500 km tangent winds are used)


 * In ATCF file the second pressure is the outer most closed isobar. Add 2 to get an environmental pressure.
 * Do not calculate central pressure if winds are below 25 knots. Instead use the mslp value given in the global analysis.

McIDAS range ring settings:

Wind ring    Range:250 km Rad:90 deg Radius 500 km

Pressure ring Range:600 km Rad:90 deg Radius 900 km