TEMPERATURE, HUMIDITY, RADIATION

There exist good long term records of air and sea temperatures at or near the main stations. The mean values of air temperatures at 0900 hrs and 1500 hrs, averaged over 15 - 17 years, rise gradually from 11º C at Point Lonsdale (LD) to 34º C at Broome (BM). The monthly mean deviations from these averages are very similar around the coast. The differences between morning and afternoon are more pronounced over the southern region. The six months of the monsoon season over the North-West and North are characterized by relatively constant deviations.

There exist few simultaneous records of water temperatures at the base stations. Data have been collected at sea during relatively rare cruises. Their mean values, shown on the inner band, vary from month to month, but are not synoptic in a true sense. Nevertheless, the reasonable correlation between the air and water temperatures long term means and the monthly means of water and air temperatures increases confidence in the water data. Along most of the coast, the water temperature appears to lag somewhat behind the air temperature, but as a rule by not more than one month. In the Gulf of Carpentaria, the water temperature reaches its minimum before the air temperature, possibly due to the heavy rainfalls in the region.

The annual means of relative humidity vary by about 20 % around the entire coast, while the amplitudes of its monthly deviations from the means cover a much wider range. Over the southern part, humidity maxima occur in Winter, over the northern part in Summer at the height of the monsoon season.

The annual means of global solar radiation vary from less than 400 m Watt/cm² at Hobart (HT) to almost 700 m Watt/cm² at Dampier (PD). The variations in the monthly means increase rapidly with latitude, so that over the southern part of Australia Winter conditions reduce this resource of energy significantly, while in the northern part it becomes a well-balanced and reliable supply.