Asian Monsoon Modeling Project

Roxy Mathew Koll, PhD

Climate Scientist, Centre for Climate Change Research

Indian Institute of Tropical Meteorology, Pune, India

The first Atmospheric Ocean Observatory (AOO) to be built and deployed by Global Oceans and the AOO Science Consortium will be deployed in the Arctic Ocean for extended atmospheric-ocean surveys. A second AOO to be built will be prioritized for research and observation deployment in the tropical Indian Ocean and Indo-Pacific region under the Asian Monsoon Modeling Project. This represents an important opportunity to fill crucial data gaps with a wide range of atmospheric observations in this region, which will in turn support the development of more accurate computational models of Asian Monsoons.

One hundred and fifty years of observations and research on monsoons over the Indian subcontinent and tropical Indo-Pacific has given us several insights into seasonal-to-decadal variability of monsoons that govern the well-being of more than a billion people in this part of the world. However, the increasing incidence of severe weather events in the recent years, underscored by a rising number of droughts, floods and cyclones, have shown us that there is much about monsoons that we do not yet understand—particularly in the light of a changing climate.

While in the past Asian monsoons were thought to have inherently low predictability, recent research has shown that improved coupled-model physics can raise our seasonal prediction skills by resolving the links between monsoon rainfall and ocean-atmosphere conditions.

Monsoons exhibit prominent variability on sub-seasonal timescales, known as Monsoon Intraseasonal Oscillation (MISO), the summer counterpart of the winter Madden-Julien Oscillation (MJO), which manifests as the wet and dry spells of rainfall over the subcontinent of India. Many of the extreme weather events like cyclones and floods across South Asia and beyond have links to MISO/MJO events in the Indian Ocean.

MISO originates in the tropical Indian Ocean and its evolution and dynamics is linked to the thermodynamical response in regions of strong ocean-atmosphere coupling. Predictions of MISO remain disappointing, with little skill beyond 20-30 days – only one half of the typical length of a MISO event. Many studies have pointed the way toward potential improvements in prediction skill through better representation of ocean-atmosphere coupling.

The new AOO facility can be utilized in extracting the salient features of ocean-atmospheric coupling, much like the CINDY/DYNAMO¹ field campaign that tracked and observed MJO events and the ocean-atmosphere coupling associated with it. Resolving the links between monsoons and ocean-atmosphere interaction will require high quality observations, simultaneously in the ocean and atmosphere domains, throughout this region.

Currently, there are major gaps in obtaining simultaneous ocean-atmosphere observations in the Indian Ocean. A recent review of the Indian Ocean Observing System (IndOOS)² points to these gaps and recommends an improvement in the network with the help of regional and international organizations.

A unique aspect of the AOO program is the capacity for deployment on MARV vessels mobilized by AOO lead partner Global Oceans, which can be adaptively project-configured for simultaneous, coordinated oceanographic and atmospheric measurements with the AOO.

The AOO facility therefore fits well into this realm, as it has the capacity as a platform to carry out these observations. By integrating the AOO facility with other research and modeling efforts, and deploying strategically across the region on MARV vessels, we can address the gaps in our monsoon observations and science, hopefully to the benefit of a significant share of the world’s population.

References

1. CINDY/DYNAMO Field Campaign: Advancing our Understanding of MJO Initiation, Chidong Zhang and Kunio Yoneyama, Book chapter in Chang, Chih-Pei. The global monsoon system: research and forecast. Vol. 5. World Scientific, 2011.

2. Beal, L. M., et al. “A roadmap to IndOOS-2: Better observations of the rapidly-warming Indian Ocean.” Bulletin of the American Meteorological Society, 101 (11): E1891–E1913.