Abstract

Hourly estimation of incoming shortwave radiation formulae have been developed and given by many scientists. The empirical formulae have to be updated with the latest realistic data. Using Lumb procedure, author attempted to give new regression coefficients for incoming shortwave radiation with in situ observations made during Arabian Sea Monsoon Experiment (ARMEX) cruises over North Indian Ocean for different cloud amounts (from clear sky to overcast conditions). ARMEX field work program has been conducted in June-August 2002 and March-June, 2003 on board R/V “Sagar Kanya”. The shortwave radiation data has been collected using the Albedometer, which is covering entire cloud amounts. Empirical formulae have been developed using sine of solar altitude (sin (h)) with respect to different could amounts. Newly developed Empirical Formulae are better and more accurate as is evidenced by standard deviation. However newly developed empirical formulae are compared with other formulae given by other scientists. The empirical formulae have been compared with available observed data from Bay of Bengal Monsoon Experiment (BOBMEX) and NCEP re-analyzed data. With BOBMEX data is in agreement, however with NCEP showing lower values.

Keywords: Shortwave radiation; Cloud; Transmission factor; Sin h; Empirical coefficients