Potensi Pengaruh Tutupan Awan dan Radiasi Matahari pada Kejadian Coral Bleaching di Wilayah Coral Triangle

Abstract

Coral Triangle merupakan pusat biodiversitas terumbu karang dunia yang mengalami peningkatan kejadian coral bleaching akibat kenaikan suhu permukaan laut, sementara peran faktor meteorologis lokal melalui mekanisme cloud radiative forcing belum banyak dikaji. Penelitian ini bertujuan menganalisis hubungan antara tutupan awan, radiasi matahari, dan suhu permukaan laut di tiga wilayah studi kasus (Filipina, Bali, dan Sulawesi) periode 1982–2016, mengkaji peran cloud radiative forcing dalam memodulasi kondisi yang berpotensi memicu coral bleaching, serta mengevaluasi pengaruh ENSO terhadap hubungan tersebut. Analisis korelasi musiman dengan lag time satu bulan menunjukkan hubungan positif antara radiasi matahari dan suhu permukaan laut yang paling kuat terjadi pada musim JFM di wilayah belahan bumi selatan dan musim JJA di wilayah belahan bumi utara. Pola ini terkonfirmasi secara spasial dan diperkuat oleh analisis komposit Degree Heating Week yang menunjukkan akumulasi stres termal karang melampaui ambang batas coral bleaching pada tahun-tahun dengan radiasi matahari tertinggi di wilayah dan musim yang sesuai. Korelasi parsial menunjukkan bahwa mekanisme cloud radiative forcing tetap berperan setelah pengaruh ENSO dihilangkan, meskipun ENSO turut memodulasi kekuatan hubungan secara musiman dan spasial.

The Coral Triangle is a global center of coral reef biodiversity that has experienced an increasing number of coral bleaching events due to rising sea surface temperature, while the role of local meteorological factors through the cloud radiative forcing mechanism remains poorly studied. This study aimed to analyze the relationship between cloud cover, solar radiation, and sea surface temperature at three case study areas (the Philippines, Bali, and Sulawesi/Tomini Bay) during 1982–2016, to examine the role of cloud radiative forcing in modulating conditions that may trigger coral bleaching, and to evaluate the influence of ENSO on these relationships. Seasonal correlation analysis with a one-month lag time showed the strongest positive relationship between solar radiation and sea surface temperature during the JFM season in the southern hemisphere area and the JJA season in the northern hemisphere area. This pattern was confirmed spatially and supported by composite Degree Heating Week analysis, which showed that coral thermal stress exceeded the bleaching threshold during years with the highest solar radiation anomalies in the corresponding region and season. Partial correlation analysis indicated that the cloud radiative forcing mechanism remained present after removing the ENSO signal, although ENSO also modulated the strength of the relationship seasonally and spatially.