Tropospheric biennial oscillation and south Asian summer monsoon rainfall in a coupled model
Type
ArticleAuthors
Konda, GopinadhChowdary, Jasti S.

Srinivas, G
Gnanaseelan, C
Parekh, Anant
Attada, Raju
Rama Krishna, S S V S
Date
2018-05-22Online Publication Date
2018-05-22Print Publication Date
2018-06Permanent link to this record
http://hdl.handle.net/10754/627985
Metadata
Show full item recordAbstract
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.Citation
Konda G, Chowdary JS, Srinivas G, Gnanaseelan C, Parekh A, et al. (2018) Tropospheric biennial oscillation and south Asian summer monsoon rainfall in a coupled model. Journal of Earth System Science 127. Available: http://dx.doi.org/10.1007/s12040-018-0948-x.Sponsors
The authors thank the Director of ESSO-IITM, Ministry of Earth Sciences (MoES), Government of India for support. Computing resources are provided by the ESSO-IITM. Figures are prepared in Grads. Authors are thankful to anonymous reviewers for their comments and suggestions, which helped us to improve the paper.Publisher
Springer NatureJournal
Journal of Earth System ScienceAdditional Links
https://link.springer.com/article/10.1007%2Fs12040-018-0948-xae974a485f413a2113503eed53cd6c53
10.1007/s12040-018-0948-x