Dynamics of Intraseasonal Oscillations in the Indian Ocean
Abstract
Intraseasonal oscillations (ISOs) significantly monitor the variability and strength of heavy rainfall associated with the Indian Summer Monsoon. Northward-propagating ISOs contribute to an increase in momentum and moisture from the tropical Indian Ocean to the Indian subcontinent that intensifies monsoonal rainfall rates. This research utilizes satellite observations and NOAA's Climate Forecast System version 2 (CFSv2) to investigate and quantify the dynamical relationship between ISOs and Indian Summer Monsoon variability. The atmospheric systems associated with monsoonal ISOs (such as Madden Julian Oscillations (MJO), quasi-biweekly oscillations, and synoptic events) induce circulation shifts that directly impact the strength and timing of active and break monsoon periods, which are respectively characterized by wet and dry conditions. This research examines the relationship between ISOs and monsoon strength by comparing how monsoonal rainfall and the tropical convergence zone (TCZ) fluctuate in years with strong and years with weak ISOs. The positioning and synoptic structure of the TCZ and how it responds to ISO-related circulation shifts are essential for improved predictability of the strength and timing of the summer monsoon onset. This novel research explores the variability of the Indian Summer Monsoon over multiple ISO periods in order to properly identify the individual contributions of the MJO (at a 30-90 day periodicity), quasi-biweekly oscillations (at a 10-20 day periodicity) and synoptic events from oscillations in the monsoon trough (at a 3-7 day periodicity) for the first time.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.A14F..06R
- Keywords:
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- 3305 Climate change and variability;
- ATMOSPHERIC PROCESSESDE: 3314 Convective processes;
- ATMOSPHERIC PROCESSESDE: 3374 Tropical meteorology;
- ATMOSPHERIC PROCESSESDE: 1637 Regional climate change;
- GLOBAL CHANGE