Performance of hydrostatic and non‐hydrostatic dynamical cores in RegCM4.6 for Indian summer monsoon simulation

Abstract

The efficacy of regional climate model RegCM4.6 using hydrostatic core resolutions at 36km (HY36) and 12km (HY12) and a non-hydrostatic core resolution at 12km (NH12) is investigated by simulating the normal, excess and deficit monsoon seasons. The ERA-Interim reanalysis data are used to drive the model and the India Meteorological Department (IMD) and modern-era retrospective analysis for research and applications (MERRA) rainfall data are used for precipitation verification. The heavy rainfall regions are well simulated in the high-compared with the coarse-resolution simulations, with the maximum in the NH12. The non-hydrostatic dynamics amalgamate the vertical acceleration with the orographic uplifting that causes more precipitation over hilly regions than that of the hydrostatic core. On the other hand, the lesser precipitation over northwest India is better portrayed in the HY12 than in the other two. Over central India, the HY36 performs better followed by the NH12; and the contrasting precipitation features are also well depicted in the HY36 and NH12. This is probably because of the better representation of large-scale monsoon features, such as a monsoon trough in the HY36 and local-scale convective activities in the NH12. Daily rainfall analysis also shows that the high-resolution model is capable of capturing the active and break phases during the El Niño and La Niña seasons. The non-hydrostatic model possesses good correlation co-efficients >0.5 over the hydrostatic model with co-efficients of 0.35. The analysis of upper air circulations and the derived parameters, including statistical tests, confirm that the RegCM4.6 with non-hydrostatics is useful for orographic regions, hydrostatic at a coarse resolution and non-hydrostatic at a finer resolution and could be suitable for plain regions.

Dynamic downscaling of climate simulations and projected changes in tropical South America using RegCM4.7

“…Currently, the model has a hydrostatic and nonhydrostatic dynamic core (Elguindi et al, 2017). Maurya et al (2020) concluded that RegCM4 with the nonhydrostatic dynamic core is useful for orographic regions with high resolution (below 12 km), whereas the coarse‐resolution hydrostatic dynamic core may be suitable for other regions.…”

A Comparative Study Between Regional Atmospheric Model Simulations Coupled and Uncoupled to a Regional Ocean Model of the Indian Summer Monsoon

“…RCMs are widely used to study the variabilities of the ISM (Bhaskaran et al., 1996, 2012; Dash et al., 2006; Jayasankar et al., 2018; Ji & Vernekar, 1997; Misra et al., 2018, 2022). The majority of the earlier dynamical downscaling studies relied on atmosphere‐only RCMs forced with prescribed SST (Ajay et al., 2019; Befort et al., 2016; Chen et al., 2018; Dash et al., 2006; Lucas‐Picher et al., 2011; Maurya et al., 2020; Mishra & Dubey, 2021; Mishra, Dubey & Dinesh, 2022; Misra et al., 2017; Pattnayak et al., 2018; Rai et al., 2020; Umakanth et al., 2016). These studies highlight the significance of the spatial resolution and especially due to improved representation of orography in high‐resolution RCMs, they outperformed their forcing global GCMs in simulating the spatio‐temporal distribution of the mean ISM rainfall.…”

An Assessment of Nonhydrostatic and Hydrostatic Dynamical Cores at Seasonal Time Scales in the Energy Exascale Earth System Model (E3SM)

“…They found that NH simulations reduce the large wet bias over the western U.S. at 12 and 36 km resolutions when a convection scheme is used. Maurya et al (2020) compared the performance of NH and H dynamical cores in a regional climate model over the India at 12 and 36 km resolutions in three monsoon seasons. The results revealed strong regionality with an inhomogeneous pattern emerging over the domain, as well as inconsistency among the three monsoon seasons, demonstrating the complexity of real-world simulations compared to the idealized simulations.…”