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- Specific humidity can be calculated over water and ice using equations 76.4 and 76.5 from Part IV, Physical processes section (Chapter 76, section 76.26.1b) in the documentation of the IFS for CY31R1. Use the 2m dew point temperature and surface pressure (which is approximately equal to the pressure at 2m) in these equations. The constants in 7.4 are to be found in Chapter 12 (of Part IV: Physical processes) and the parameters in 7.5 should be set for saturation over water because the dew point temperature is being used.
- Relative humidity should be calculated: RH = 100 * es(Td)/es(T)
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