Bay of Bengal intraseasonal oscillations and the 2018 monsoon onset

Here, we summarize the 2018 monsoon onset using observations collected through the multinational Monsoon Intraseasonal Oscillations in the Bay of Bengal (MISO-BoB) program between the United States, India, and Sri Lanka. MISO-BoB aims to improve understanding of monsoon intraseasonal variability, and the 2018 field effort captured the coupled air-sea response during a transition from active-to-break conditions in the central BoB.

The active phase of the similar to 20-day research cruise was characterized by warm sea surface temperature (SST > 30 degrees C), cold atmospheric outflows with intermittent heavy rainfall, and increasing winds (from 2 to 15 m s(-1)). Accumulated rainfall exceeded 200 mm with 90% of precipitation occurring during the first week. The following break period was both dry and clear, with persistent 10-12 m s(-1) wind and evaporation of 0.2 mm h(-1).