Geometric mean diameter of sea salt aerosols in CMAQv5.0.2

CMAQ
2

Hello,

These lines in SSEMIS.F show how the RH is mapped to the mean diameters and standard deviations:

`
C Find position in the data arrays that corresponds to ambient RH in this
C grid cell and set the appropriate data values

              IF ( BLKRH .LE. 0.45 ) THEN
                 IPOS = 1
              ELSE IF ( BLKRH .LE. 0.90 ) THEN
                 IPOS = NINT( 100.0 * BLKRH - 44.0 )
              ELSE IF ( BLKRH .LE. 0.99 ) THEN
                 IPOS = NINT( 1000.0 * BLKRH - 854.0 )
              ELSE
                 IPOS = 136
              END IF

`
IPOS is then the index used to lookup the value of the diameter or standard deviation in the lookup tables. As you can see, the first index is for 45% RH and below, the next 45 indices correspond to increasing RH by 1%, then the next 90 indices correspond to increases by 0.1%. The values in the table are not averaged together, neither geometrically nor arithmetically.

The default diameters prescribed in AERO_DATA.F are not relevant for sea spray aerosol emissions. Those diameters are used mainly for boundary conditions when size distributions from the boundary data appear to be non-physical.

Best regards,
Ben Murphy