Variable Calculation Details
- dT/dp:
- Calculated as T(p+1)-T(p)/dp where p is the level above the one selected (a one sided difference). Results per displayed as per 100mb to match d/dz values better.
- dT/dz:
- Calculated as T(p+1)-T(p-1)/dz where dz is from the NCEP/NCAR Reanalysis geopotential height. Results displayed as K/km. Positive values indicate a decrease of temperature upward.
- 500-700mb lapse rate:
- (T(500)-T(700)(/(500mb-700mb). Positive values indicate a decrease of temperature upward.
- LCL surface (.995sigma):
- :
Based on Fortran program calcsound of Kerry Emanuel
CHI=TS/(1669.0-122.0*RH-TS)
P(LCL)=p*(RH**CHI)
- Dew Point:
- :
A=T-273.15
X = 1.-0.01*RH
DPD =(14.55+0.114*A)*X+
& ((2.5+0.007*A)*X)**3+(15.9+0.117*A)*X**14
DEW POINT= A-DPD
- Mixing Ratio
- Calculated AT a level.
rh= decimel, p=mb, T=K
w=(rh*wsb)/(1.+((1.-rh)*wsb)/e)
e=.622
wsb=e*es/(p-es)
ws=6.112*exp(17.67*(t-273.15)/(t-29.65))
- Equivalent Potential Temperature
- Calculated AT a level.
I use formula supplied by Paul Neiman which uses entropy. Will post later.
- Freezing Level
-
Level (mb for now) which is less than freezing (273.15K). Pressure level is interpolated using log pressure weighting.
If surface is freezing, level is "missing".
- Moisture Flux:
- specific humidity times the vector wind (u,v) at a level. units are g/kg * m/s
- Integrated Moisture Flux:
- specific humidity times vector wind integrated from the surface to 300mb.Each layer is multiplied by the pressure of that level and the final result is divided by g. Values are computed between levels. For example, the 925 to 850 layer as the average of 1 and vector wind for that layer multiplied by 12500 Pascals.
|