IPB University Lecturer Says CENS Phenomenon Triggers Anomalous Early Rainfall Patterns in Java
There are different characteristics and patterns at the peak of this year’s early rainy season. Sonni Setiawan, SSi, MSi, a lecturer at the Department of Geophysics and Meteorology at IPB University, revealed that there are anomalies in rainfall patterns caused by various factors.
“The high intensity of rainfall in several regions of Indonesia, particularly Java Island, does follow the Asian monsoon, but its frequency is quite intense. This has led to flooding, a drop in air temperature, strong winds, and health complaints,” he said.
He further explained that based on satellite imagery observations and daily weather monitoring, there are indications of other atmospheric factors amplifying the Asian monsoon rainfall at the beginning of this year.
“Based on the patterns I obtained from the observation data, I suspect that there is another factor that strengthens the monsoon rainfall, namely the CENS (Cross Equatorial North Surge) phenomenon,” he explained.
Sonny said that CENS is the movement of cold air masses from southern China that are able to cross the equator and move to Indonesia, including Java. This phenomenon is considered to have a significant impact on weather conditions.
“CENS not only causes a decrease in air temperature, but also increases cloud formation. This occurs due to the meeting of cold, dry air from southern China with warm, humid tropical air,” he said.
When two air masses with different temperatures meet, a process of adjustment towards thermal equilibrium occurs. The warm, humid tropical air experiences a decrease in temperature, causing the water vapor in it to cool and condense.
“This condensation process produces more clouds. As a result, sunlight has difficulty reaching the earth’s surface, causing the air between the surface and the base of the clouds to cool down,” he said.
He added that, potentially, these conditions are similar to the major flooding that occurred in Semarang on February 5-6, 2021. Based on the latest weather images, Java Island appears to be covered by thick clouds, with CENS flows from southern China to Java still active.
“In addition, a tropical cyclone has also been detected in the southeast of Java Island. This combination has the potential to worsen the weather, especially in the southern part of East Java,” he added.
He concluded that the weather phenomenon currently being experienced by the community is the result of a complex interaction between the Asian monsoon, CENS, and other atmospheric dynamics.
“My assumption, based on observation data, is that CENS acts as an amplifying factor that intensifies the rainfall of the Asian monsoon during this period. Additionally, the presence of a tropical cyclone in the southeast of Java Island near Australia appears to be blocking the CENS, resulting in the formation of more clouds than usual,” he concluded. (AS)(IAAS/KDP)
