An 11-year Climatology of Cloud Properties over the Great Barrier Reef as Observed by A-Train Satellites — Australian Meteorological and Oceanographic Society
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  3. An 11-year Climatology of Cloud Properties over the Great Barrier Reef as Observed by A-Train Satellites

An 11-year Climatology of Cloud Properties over the Great Barrier Reef as Observed by A-Train Satellites (#2011)

Wenhui Zhao 1 , Yi Huang 2 3 , Steven Siems 1 4 , Michael Manton 1
  1. School of Earth, Atmosphere and Environment, Monash University, CLAYTON, Victoria, Australia
  2. The University of Melbourne, Parkvale, VIC, Australia
  3. ARC Centre of Excellence for Climate Extremes, The University of Melbourne, Melbourne, Victoria, Australia
  4. Australian Research Council (ARC) Centre of Excellence for Climate Extremes, Monash University, CLAYTON, Victoria, Australia

The Great Barrier Reef (GBR) is known to face a number of threats including widespread coral bleaching events. Climate change, via increasing sea surface temperature (SST), is the most significant threat to the status of GBR. While the prospect of clouds playing a key role in governing the SST over the GBR has been raised in recent studies, a fundamental understanding of cloud climatology in this region is lacking.

This study employs 11-year (2007-2017) observations from CloudSat and CALIPSO satellites to establish a climatology of cloud properties over the GBR region (10-30ºS, 140-160ºE). The overall frequency of cloud occurrence (FCO) is ~60%, with a clear seasonal variation. The maximum FCO (~70%) is present in Austral summer (DJF) whereas the minimum (~50%) occurs in Austral winter (JJA). The vertical distribution of FCO exhibits a bimodal pattern peaking at 2km and 15km, dominated by marine cumulus / stratocumulus and high-level cirrus cloud types, respectively. More high clouds are observed in summer while more low clouds are present in winter. Geographically, larger FCOs (~80%) are observed over the low-latitude ocean. In low latitudes, more high (cirrus) clouds are observed over the ocean while more altocumulus appears over land. Stratocumulus and cumulus are most common in the southeast ocean area (~30%). A diurnal cycle is also evident, with larger FCOs observed during night time, irrespective of seasons and altitudes.

Cloud thermodynamic phase properties are also explored. Ice phase in association with high-level cirrus is most frequently observed over the northern part of the domain and it extends southward from day to night. This pattern is more pronounced in summer, which is likely a result of the southward shift of the tropical convection belt. Liquid phase is mostly observed over the southeast ocean area during daytime, commonly associated with cumulus / stratocumulus cloud types.

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