Initialise the air-sea interaction module

INTERFACE:

    subroutine init_air_sea(namlst,lat,lon)

DESCRIPTION:

This routine initialises the air-sea module by reading various variables from the namelist airsea.nml and opens relevant files. These parameters are:

calc_fluxes	.true.: Sensible, latent and back-radiation are calculated by
	means of bulk formulae. In this case, meteo_file must be
	given and hum_method must be specified.
	.false.: Surface fluxes and solar radiation are prescribed.
fluxes_method	Select which parameterisation to use for latent and sensible fluxes:
	1: Kondo (1975)
	2: Fairall et al. (1996)
back_radiation_method	Select which parameterisation to use:
	1: Clark et al. (1974)
	2: Hastenrath and Lamb (1978)
	3: Bignami et al. (1995)
	4: Berliandand Berliand (1952)
meteo_file	file with meteo data (for calc_fluxes=.true.) with
	date: yyyy-mm-dd hh:mm:ss
	$x$-component of wind (10 m) in ms$^{-1}$
	$y$-component of wind (10 m) in ms$^{-1}$
	air pressure (2 m) in hectopascal
	dry air temperature (2 m) in Celsius
	rel. hum. in % or wet bulb temp. in C or dew point temp. in C
	cloud cover in 1/10
	Example:
	1998-01-01 00:00:00 6.87 10.95 1013.0 6.80 73.2 0.91
hum_method	1: relative humidity given as 7. column in meteo_file
	2: wet bulb temperature given as 7. column in meteo_file
	3: dew point temperature given as 7. column in meteo_file
heat_method	0: heat flux not prescribed
	1: constant value for short wave radiation (const_swr)
	and surface heat flux (const_qh)
	2: swr, heat are read from heatflux_file
rain_impact	.true.: include sensible- and momentum-flux from precipitation
calc_evaporation	.true.: calculate evaporation/condensation (m/s)
swr_method	1: constant value for short wave radiation (const_swr)
	2: read short wave radiation from file
	3: Solar radiation is calculated from time, longitude, latitude,
	and cloud cover.
const_swr	constant value for short wave radiation in Wm$^{-2}$
	(always positive)
swr_file	file with short wave radiation in Wm$^{-2}$
swr_factor	scales data read from file to Wm$^{-2}$ - defaults to 1
const_heat	constant value for surface heat flux in Wm$^{-2}$
	(negative for heat loss)
heatflux_file	file with date and heat in Wm$^{-2}$
momentum_method	0: momentum flux not prescribed
	1: constant momentum fluxes const_tx, const_tx given
	2: surface momentum fluxes given from file momentumflux_file
const_tx	$x$-component of constant surface momentum flux in Nm$^{-2}$
const_ty	$y$-component of constant surface momentum flux in Nm$^{-2}$
momentumflux_file	File with date, tx and ty given
precip_method	0: precipitation not included == precip=0.
	1: constant value for precipitation in ms$^{-1}$
	2: values for precipitation read from file precip_file
const_precip	value for precip in ms$^{-1}$
precip_file	file with date and precip in ms$^{-1}$
precip_factor	scales data read from file to ms$^{-1}$ - defaults to 1
sst_method	0: no independent SST observation is read from file
	2: independent SST observation is read from file, only for output
sst_file	file with date and SST (sea surface temperature) in Celsius
sss_method	0: no independent SSS observation is read from file
	2: independent SSS observation is read from file, only for output
sss_file	file with date and SSS (sea surface salinity) in psu

USES:

    IMPLICIT NONE

INPUT PARAMETERS:

    integer, intent(in)                 :: namlst
    REALTYPE, intent(in)                :: lat,lon

REVISION HISTORY:

    Original author(s): Karsten Bolding
    See log for airsea module