Progress Towards Achieving the Challenge of Indian Summer Monsoon Climate Simulation in a Coupled Ocean‐Atmosphere Model. (14th October 2017)

• Record Type: Journal Article
• Authors: Hazra, Anupam; Chaudhari, Hemantkumar S.; Saha, Subodh Kumar; Pokhrel, Samir; Goswami, B. N.
• Is Part Of: Journal of advances in modeling earth systems. Volume 9:Number 6(2017)
• Page Start: 2268
• Page End: 2290
• Publication Date: 2017-10-14
• Subjects: monsoon intraseasonal oscillations -- coupled climate model -- convective microphysics; Geological modeling -- Periodicals; Climatology -- Periodicals; Geochemical modeling -- Periodicals; 551.5011
• DOI: 10.1002/2017MS000966
• Languages: English
• ISSNs: 1942-2466

Abstract

Abstract: Simulation of the spatial and temporal structure of the monsoon intraseasonal oscillations (MISOs), which have effects on the seasonal mean and annual cycle of Indian summer monsoon (ISM) rainfall, remains a grand challenge for the state‐of‐the‐art global coupled models. Biases in simulation of the amplitude and northward propagation of MISOs and related dry rainfall bias over ISM region in climate models are limiting the current skill of monsoon prediction. Recent observations indicate that the convective microphysics of clouds may be critical in simulating the observed MISOs. The hypothesis is strongly supported by high fidelity in simulation of the amplitude and space‐time spectra of MISO by a coupled climate model, when our physically based modified cloud microphysics scheme is implemented in conjunction with a modified new Simple Arakawa Schubert (nSAS) convective parameterization scheme. Improved simulation of MISOs appears to have been aided by much improved simulation of the observed high cloud fraction and convective to stratiform rain fractions and resulted into a much improved simulation of the ISM rainfall, monsoon onset, and the annual cycle. Key Points: A physically based modified convective microphysics scheme is implemented in the NCEP CFSv2 The convective microphysics is found to be important for simulating the observed monsoon intraseasonal oscillations (MISOs) High fidelity in the simulation of MISOs in association with improved stratiform rain fraction leads to the improved seasonal mean ISMR