WEEKLY CYCLE OF METEOROLOGICAL VARIATIONS IN MELBOURNE AND THE ROLE OF POLLUTION AND ANTHROPOGENIC HEAT RELEASE

An aspect of anthropogenic impacts on climate have been assessed by ex amining the day-of-the-week variation (DOWV) of important meteorologic al elements. The data used were those of daily maximum and minimum tem perature and rainfall for Melbourne for the period 1856-1990. This lon g series has been broken up into five 27-yr subperiods to expose how a ny such variation has changed over the record. We find there to be no DOWV in the summer ''half'' of the year for any of the subperiods. The only statistically significant variations to have physical meaning oc cur in the winter of the most recent subperiod (1964-1990). In that ti me maximum temperature exhibits a significant (10% confidence level) D OWV and weekdays are 0.29 degrees C warmer than weekends (5%). Minimum temperatures and rainfall amounts were also found to be greater (10% level) on weekdays by 0.24 degrees C and 0.20 mm d(-1), respectively. We have considered the possible impacts of day-of-the-week variation o f atmospheric pollution loading and of the local generation of heat. W e hypothesise that the magnitude of the contrast between weekday-weeke nd anthropogenic heat emissions is sufficient to explain the temperatu re differences and these in turn are consistent with the weekday exces s of rainfall. This perspective is concordant with the results of many recent studies which stress the importance of anthropogenic heating. (C) 1997 Elsevier Science Ltd.