Estimation of turbidity and global radiation over Jeddah in spring

الملخص EN

An experiment was performed for estimation of turbidity over Jeddah during Spring (March, April and May 1993).

The measurements include direct, diffuse and global radiation, on elear days.

The data are also incorporated in a radiation mode) for estimation of dif- ferent components of solar radiation over Jeddah.

The results showed that the turbidity and consequently the amount of aerosols in the atmosphere was max- imum in April.

This was accompanied by a strong south to southwest wind.

The coclTieienl of turbidity (/}) reached (0.9) oil 6 April, a very turbid day.

On this day.

the wave length exponent (a) approached zero.

The diurnal variation of the turbidity showed an increase started at noon and extended all afternoon.

The average Spring turbidity in Jeddah is (0.18).

The results of the model indi- cate that the average percentage difference between the measured and the cal- culated direct, diffuse and global radialion are 8 %, 15%- and 5% respectively.

The model used was successful, with an over all precision for direct and global radiation of 10% for Jeddah.

This gives confidence that this model probably with some improvements, can be used for estimating global radiation over Jeddah on clear days when measurements of this parameters are not available.