Scientific background

Studies on the air mass modification process and structure at the head of cold surge are very few in the past.

Issues:

1. what air mass modification processes at the head of cold surge are there across the equator?

2. detailed dynamic processes of circulation systems and interaction between diurnal cycle and large-scale surge in and around the intricate terrain of Java, Sumatra, and Borneo islands.

It is difficult to approach the above issues only by using existed objective analysis datasets and satellite products.

We strongly expect to produce results with originality and novelty after intensive observation campaign to approach the above issues.

The above issues are raised from the past results of the BMKG-JAMSTEC collaboration and the significance of our efforts should be great on the foundation we built.

Cold surge:

cold air outbreak near the surface from the cold high pressure over Eurasian continent to the Pacific Ocean in boreal winter. From Dec. to Mar., a large-scale northerly flow reaching up to the Tropics continues for about a weak in approximately once per month.

Cross equatorial northerly surge:

surface northerly wind surge sometimes crosses over the equator in inland sea of Indonesia (southern part of South China Sea and Java Sea) and it is distinguished from the ordinary cold surge. It influences convection over Java Sea and Java island and sometimes induces heavy rainfall.