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| Abstract Submission No. | ABS-2022-07-0394 |
| Title of Abstract | Westward Propagating Quasi-Biweekly Oscillation in CAM51with Aquaplanet-like Configuration |
| Authors | Surajit Das*, Jai Sukhatme, Arindam Chakraborty, Debasis Sengupta |
| Organisation | Indian Institute of Science |
| Address | Bangalore Bangalore, Karnataka, India Pincode: 560012 Mobile: 9945675023 E-mail: srjt.ds@gmail.com |
| Country | India |
| Presentation | Poster |
| Abstract | The study illustrates the characteristics of the quasi-biweekly oscillation (QBWO) in CAM5 with March equinox condition and zonally symmetric SST configuration with and without continents. The model results are compared with the 21 years (1995⿿2015) of ERA-Interim reanalysis data. The aquaplanet mode of the model produces double ITCZ on both sides of the equator. When the continents are introduced with realistic orography and interactive surface properties, the ITCZ gets strengthened over the Pacific Ocean in the northern hemisphere. The QBWO signal dwells inside the envelope of total precipitable water for both the observation and the model. The analysis of the 10⿿25 days filtered model precipitation between 10N to 24N shows that the aquaplanet mode produces a weak signal compared to the observed QBWO activity over the Western North Pacific in boreal summer. In the presence of the continents, the intensity of the signal resembles the observation. The propagation dynamics and the maintenance mechanism of the QBWO are studied by using the vorticity budget and the moist static energy (MSE) budget analysis. The model data, as well as the observation, suggest that the advection due toβ effect plays the crucial role for the northwestward propagation of QBWO associated vorticity while the propagation of the column MSE anomaly occurs mainly due to the horizontal advection of MSE. The surface heat flux and the vertical MSE advection is the most dominant contributor for the growth and maintenance of column MSE anomaly for observation and model respectively. However, the surface heat flux also has a significant contribution on growing the QBWO associated MSE anomaly in the presence of land in the model while, in the aquaplanet mode, it shows negligible impact. |