LOOKUP TABLE
-------------

Data files needed for lookup table 

(1) uten.dat:  contains 10 meter wind speed. Wind speed is a function
               of ustar and air/sea temperature difference

(2) lookup_data.dat: contains data used to construct lookup table
                     (e.g., ustar and SST-Tair)


Programs needed for lookup table

(1) lookup_kara.f90: (subroutine) returns 10 meter wind speed as a function
                      of 'ustar' and 'SST-Tair'

(2) read_lookup_data.f90: (subroutine) reads data used to construct 
                           lookup table and corresponding 10 meter 
                           wind speed

(3) lookup_kara_mod.f90: (MODULE) used to share data 



TEST PROGRAM FILES
------------------

(1) test_lookup_kara.f90: (main program) Used to test lookup table and  
                          shows the structure of main 
                          program and calling sequence of the module and 
                          subroutines. The correct calling sequence greatly 
                          improves the time efficiency of the flux table.
                          This is important when incorporting the flux table 
                          into a larger models.  

(2) test_input_data.dat: (data file) example file used for input into 
                          lookup table. File contains:

                                 1)Wind Speed
                                 2)ustar
                                 3)ustar^2 (i.e., stress/density)
                                 4)Sea surface temperature
                                 5)Air temperature
                                 6)SST-Tair


COMPILATION
-----------

To compile type:

f90 lookup_kara_mod.f90 read_lookup_data.f90 lookup_kara.f90 test_lookup_kara.f90


 


DESCRIPTION OF LOOKUP TABLE SUBROUTINE
---------------------------------------

The lookup table is constructed using a surface flux model (Bourassa 2006) 
to compute the wind speed (at 10 m) as a function of friction velocity (ustar)
and air/sea temperature differences (SST - Tair).  The wind speed is 
computed for a range of ustar (0.0 to 3.0 m) and air/sea temperature
difference (-15.0 to 15.0 Celsius) values.  The lookup table determines a 
10 m wind speed, using a bilinear interpolation scheme, corresponding to 
an user specified stress (at 10 m), sea surface temperature, and 
air temperature (at 10 m). More specifically, the user must imput stress
divided by the density of air.  Prior to determining the 10 m windspeed 
the friction velocity is calculated via:

                     ustar = SQRT(stress/density)

In addition, the sea surface temperature and air temperature are converted 
to potential temperature using

                     Theta = T + (g/cp)*z

where z equals 10 m. The air/sea temperature difference is then computed 
using the corresponding theta values.  


Reference:

Bourassa, M.A. (2006), Satellite-based observations of surface turbulent
   stress during severe weather, Atmosphere-ocean interactions, Vol 2., 
   W. Perrie, 35-52, Wessex Institute of Technology.        




SUBROUTINE lookup_kara(tau_over_rho, t_sst, t_air, uten_out)

! PURPOSE: Subroutine determines 10 meter wind speed from a specified
!          stress/density, air temperature, and sea surface temperature
!
! INPUT VARIABLES:  (1) Stress divided by density of air (tau_over_rho)
!
!                               tau/rho = ustar^2
!
!                   (2) Sea surface temperature (t_sst) [degrees C]
!
!                   (3) Air temperature @ 10 meters (t_air) [degrees C] 
!
!
! OUTPUT VARIABLES: (1) Corresponding wind speed at 10 meters (uten_out)
!                       (m/s)
!
!
! RANGE OF LOOKUP TABLE:  0.0 <= ustar < 3.0 [increment 0.1]
!                        -15.0  < t_sst - t_air < 15.0 [increment 1.0]
!
!            *** If additional ranges needed please contact ***