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Abstract Submission No. | ABS-2022-04-0131 |
Title of Abstract | Which product is potentially more reliable among the heat flux products available over Indian ocean in daily to annual scale?A statistical and comparative study. |
Authors | Ushnanshu Dutta*, Samir Pokhrel, Hasibur Rahman, Hemantkumar Chaudhari, Anupam Hazra, Subodh Kumar Saha, Chinta Veeranjaneyulu |
Organisation | Indian Institute of Tropical Meteorology |
Address | Hydro Lab, Main Building, IITM Pune, Pashan Road Pune, Maharashtra, India Pincode: 411008 Mobile: 8788756089 E-mail: ushnanshudutta@gmail.com |
Country | India |
Presentation | Oral |
Abstract | In this study net heat flux (Qnet) and its components from four reanalyses (NCEP-2, CFSR, ERA5 & MERRA) and two blended products (OAFlux & TropFlux) are compared with in-situ observation (two RAMA buoys and one independent WHOI buoy) over the north Indian Ocean to better quantify their uncertainties in daily, seasonal and annual scale. These comparisons are essential to reconfirm the present status of Qnet error. The root mean square error (RMSE) remains as large 2-3 times the mean value, similar to the RMSE a decade earlier, despite the new advancement in the flux data having better observation and improved reanalysis models. There is a clear separation of flux quality from older generation reanalysis (NCEP-2) to newer generation reanalysis (MERRA, CFSR and ERA5) as evident by significant improvement in spatial distribution and buoy location comparisons. Taylor and time series plots demonstrates that while individually ERA5 provides the best estimate of all the flux components, the ensemble mean (i.e. average of ERA5, CFSR, MERRA, TropFlux and OAFlux) being close to ERA5 both in correlations and RMSE for all flux components provides the most reliable estimate by virtue of removal of some of the uncertainty in estimation of flux by each of the flux products. Significant reduction of RMSE of Qnet estimates from 100 W/m2 in NCEP-2 to 45 W/m2 in the ensemble mean is a major progress. It is noteworthy that all the recent flux products estimate the increasing trend in the north BoB and sub-seasonal fluctuations with considerable fidelity. Also, in the south of equator location as well they estimate the lack of trend during the pre-monsoon months and vigorous sub-seasonal fluctuations in boreal winter are well captured. We believe this is also a major progress in estimation of Qnet over the Indian Ocean. Further, this study is important to identify the most reliable heat flux product available over the tropical Indian Ocean domain and to check present day coupled models for their ability to simulate the regional and seasonal dependence of Qnet controlled SST variability. |