Cloud cover, cloud properties, and the change in cloud cover over time are important variables to quantify in planning for ground-space bidirectional high bandwidth optical communication systems. As operators of optical communication systems will endeavor to function when skies have optically thin cloud cover, a climatological study that includes cloud physics in the dataset (i.e., cloud emissivity and cloud optical depth) will provide beneficial guidance. As a first step in undertaking such an investigation, we have initiated a study of the Australian continent with the aim of identifying any significant decadal trends in cloud climatology over a 40-year period. The database, covering PATMOS-x AVHRR cloud data from 1979 to 2018, includes sampling of the climatology at four times during the diurnal cycle so that selection of operating conditions can be further analyzed. Examples of the spatial and temporal variability of satellite-derived cloud fractional amounts over Australia will be presented along with an approach to analyzing and interpreting this information in aid of the decision-making process to optimize clear-sky optical ground station positioning. When used in conjunction with the average monthly cloud amount, monthly specific decadal time-specific anomalies can highlight when and where minimum levels of cloud cover occur.

Chapter Contents:

• 37.1 Introduction
• 37.1.1 Australian cloud climatology studies
• 37.1.2 The 40-year satellite climatology record
• 37.1.3 The AVHRR instrument
• 37.1.4 The cloud detection scheme employed by PATMOS-x
• 37.1.4.1 Mid-morning (AM) and mid-afternoon (PM) data
• 37.1.4.2 Nighttime (N1) and early morning (N2) data
• 37.2 Climate change and decadal trends in cloud statistics
• 37.3 Discussion of results
• 37.4 Conclusions
• Acknowledgments
• References

Inspec keywords: clouds; remote sensing; atmospheric optics; atmospheric radiation; climatology

Other keywords: clear-sky optical ground station positioning; cloud properties; cloud emissivity; ground-space bidirectional high bandwidth optical communication systems; cloud cover; average monthly cloud amount; cloud climatology; satellite-derived cloud fractional amounts; cloud physics; 40-year cloud climatological study; laser communication infrastructure; cloud optical depth; PATMOS-x AVHRR cloud data

Subjects: Climatology; Instrumentation and techniques for geophysical, hydrospheric and lower atmosphere research; Cloud physics