Clouds in Darwin and their relation to large-scale conditions

This thesis provides a climatological overview of the cloudiness in the Darwin region in the very north of Australia. Information on cloud top pressure and optical thickness from the ISCCP Stage D1 data set over the time period 1985 to 2000 has been used to examine how the cloud cover changes over the course of a year, and also how it is affected by the seasonal changes in the region. The most remarkable changes can be seen during the wet summer season, when wet westerly winds sweep in over Darwin and dramatically change the weather conditions. Using cluster analysis to divide the cloud cover into cloud regimes, an interesting link between rainfall trends and cloud cover trends can be detected - a link that cannot as easily be seen when just looking at the average cloud cover. Furthermore, these regimes are also used to examine how the Darwin area is affected by large-scale atmospheric phenomena such as the intra-seasonal Madden Julian Oscillation (MJO) and the El Niño/Southern Oscillation (ENSO). The research has been carried out at the Australian Bureau of Meteorology Research Centre and at the School of Mathematical Sciences at Monash University, both in Melbourne, Australia.Validerat; 20101217 (root