Tropospheric biennial oscillation and south Asian summer monsoon rainfall in a coupled model

Gopinadh Konda, Jasti S. Chowdary, G Srinivas, C Gnanaseelan, Anant Parekh, Raju Attada, S S V S Rama Krishna

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

In this study Tropospheric Biennial Oscillation (TBO) and south Asian summer monsoon rainfall are examined in the National Centers for Environmental Prediction (NCEP) Climate Forecast System (CFSv2) hindcast. High correlation between the observations and model TBO index suggests that the model is able to capture most of the TBO years. Spatial patterns of rainfall anomalies associated with positive TBO over the south Asian region are better represented in the model as in the observations. However, the model predicted rainfall anomaly patterns associated with negative TBO years are improper and magnitudes are underestimated compared to the observations. It is noted that positive (negative) TBO is associated with La Niña (El Niño) like Sea surface temperature (SST) anomalies in the model. This leads to the fact that model TBO is El Niño-Southern Oscillation (ENSO) driven, while in the observations Indian Ocean Dipole (IOD) also plays a role in the negative TBO phase. Detailed analysis suggests that the negative TBO rainfall anomaly pattern in the model is highly influenced by improper teleconnections allied to IOD. Unlike in the observations, rainfall anomalies over the south Asian region are anti-correlated with IOD index in CFSv2. Further, summer monsoon rainfall over south Asian region is highly correlated with IOD western pole than eastern pole in CFSv2 in contrast to the observations. Altogether, the present study highlights the importance of improving Indian Ocean SST teleconnections to south Asian summer rainfall in the model by enhancing the predictability of TBO. This in turn would improve monsoon rainfall prediction skill of the model.
Original languageEnglish (US)
JournalJournal of Earth System Science
Volume127
Issue number4
DOIs
StatePublished - May 22 2018

Fingerprint

Dive into the research topics of 'Tropospheric biennial oscillation and south Asian summer monsoon rainfall in a coupled model'. Together they form a unique fingerprint.

Cite this