Title

Trends of Night-Time Hourly Cloud-Cover Values Over Manila Observatory: Ground-Based Remote-Sensing Observations Using a Digital Camera for 13 Months

Document Type

Article

Publication Date

7-3-2018

Abstract

Night-time cloud detection provides data sets of cloud-cover percentage. Although night-time cloud-cover data sets from satellite-based instruments are common, these data sets do not have relatively high temporal resolution. To quantify local temporal cloud-cover variability and to attain long-term cloud-cover measurements, ground-based instruments would be the appropriate apparatus. In this study, a digital camera is used to continuously gather images of the night sky at 5-min intervals over Manila Observatory (14.64° N, 121.07° E). For the first time in Manila, ground-based remote-sensing data gathered from October 2015 to October 2016 are analysed for hourly cloud cover. The results indicate that wet season has relatively higher cloud-cover values (median >40%) as compared to the dry season (median <40%). Moreover, cloud-cover values are observed to decrease during the night. For the wet season, August having the highest cloud-cover values has the highest value of change of hourly cloud-cover percentage (−0.82% h−1). For the dry season, February having the lowest cloud-cover values has the highest value of change of hourly cloud-cover percentage (−1.04% h−1).

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