# Jwtype

From WikiROMS

Jwtype

**Jwtype**- Jerlov water type: an integer value from 1 to 5.
**option =****routine =**mod_mixing.F**keyword =**WTYPE**input =**roms.in

This parameter selects amongst a set of coefficients that define the double exponential profile for shortwave radiation absorption calculated by Paulson and Simpson's (1977) fit to the data of Jerlov (1976).

WTYPE (roms.in) values 1 through 5 correspond to Jerlov's classification of water types I, IA, IB, II and III, respectively.

The model for the downward flux of solar radiation is:

where is the downward shortwave radiation at the sea surface. This parameterization is implemented in lmd_swfrac.F if called for. Downward shortwave data (or an analytical value) is required as input.

The parameters of this simple optical model are described and set in mod_scalars.F in the block headed "Water clarity parameters":

lmd_mu1 Reciprocal of the absorption coefficient for solar wavelength band 1 as a function of the Jerlov water type. Units are meters. lmd_mu2 Reciprocal of the absorption coefficient for solar wavelength band 2 as a function of the Jerlov water type. Units are meters. lmd_r1 Fraction of total radiance for wavelength band 1 as a function of the Jerlov water type.

The values are:

WTYPE 1 2 3 4 5 Jerlov water type : I IA IB II III lmd_mu1 0.35 , 0.60 , 1.00 , 1.50 , 1.40 lmd_mu2 23.00 , 20.00 , 17.00 , 14.00 , 7.90 lmd_r1 0.58 , 0.62 , 0.67 , 0.77 , 0.78