FY 1976

An evaluation of formulas for estimating clear-sky insolation over the ocean

Reed, R.K.

NOAA Tech. Report ERL 352-PMEL 26, NTIS: PB-253055/8, 25 pp (1975)

Recent oceanic data and observations from five coastal sites in the National Weather Service solar radiation network are compared with a formula for computing clear-sky insolation derived from the Smithsonian Meteorological Tables, using a transmission coefficient of 0.7. The results are generally in good agreement, and they suggest that this formula is suitable for computing insolation over the ocean for a wide range of latitudes. The comparison also indicates that a correction to the formula for middle latitudes is not warranted. The one other formula in good agreement with that from the Smithsonian Tables is one derived by Lumb; Laevastu's formula is only acceptable at sun angles less than 50°, and Berliand's estimates are too high at all solar altitudes. The formula from the Smithsonian Tables can be used to compute insolation over the oceans with a random error of estimate probably not exceeding 5% for periods of a few days or longer.