pro virtotemp,mixrat,virtemp,airtemp,badval

; Converts virtual temperature into temperature.
; KJ Davis, December, 1998.

;INPUTS
;  MIXRAT - dry air mixing ratio in g H2O/kg dry air
;  VIRTEMP - virtual temperature in K
;  BADVAL - bad data value marker (usually -999)
;OUTPUTS
;  AIRTEMP - air temperature in K.

; Ratio of water vapor gram molecular weight to 'dry air' gram
; molecular weight is EPS
eps = 0.622
; Convert mixing ratio from g/kg to kg/kg
mixr=mixrat/1000.

if ((mixrat ne badval) and (virtemp ne badval)) then begin

; See Wallace and Hobbs, 1977, for the conversion from temperature to
; virtual temperature.
    airtemp=virtemp*(1.- (mixr/(mixr+eps))*(1.-eps))

endif else begin
    airtemp=badval
endelse

;debugging/testing stop
;stop

return
end