Representation of monsoon intraseasonal oscillations in regional climate model: sensitivity to convective physics

Uppara, Umakanth; Kesarkar, Amit P.; Attada, Raju; Rao, Sandhya

doi:10.1007/s00382-015-2878-5

Cited by 27 publications

(13 citation statements)

References 66 publications

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“…1g), which differ only in the cumulus scheme (Table 2), were compared to test the sensitivity of the WRF-simulated precipitation to the cumulus scheme used in the model. Not surprisingly, the comparison shows the model-simulated precipitation to be sensitive to the cumulus parameterization scheme, in agreement with the previous studies of Mukhopadhyay et al (2010), Srinivas et al (2013) Raju et al (2015), and Umakanth et al (2016). We calculated the root mean square error (RMSE; Fig.…”

Section: Sensitivity To Cumulus Parameterization Schemessupporting

confidence: 73%

“…Several studies have shown that RCMs are capable of realistically simulating the Indian summer monsoon precipitation at seasonal (Jacob & Podzum 1997, Vernekar & Ji 1999 as well as at subseasonal (Maharana & Dimri 2016, Umakanth et al 2016) time scales. However, the simulated precipitation has been found to be sensitive to the cumulus parameterization schemes used in the RCMs (Ratnam & Kumar 2005, Dash et al 2006, Mukhopadhyay et al 2010, Raju et al 2015, Umakanth et al 2016 at both seasonal and sub-seasonal time scales. A few studies, such as that of Shrivastava et al (2014), highlight the importance of choosing a suitable combination of parameterization schemes within the WRF model to simulate the features over the Indian region.…”

Section: Introductionmentioning

confidence: 99%

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Sensitivity of Indian summer monsoon simulation to physical parameterization schemes in the WRF model

et al. 2017

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A set of 17 experiments, using various combinations of physical parameterization schemes in the Weather Research and Forecasting (WRF) model, were carried out to choose a combination suitable for simulating the Indian summer monsoon. The model experiments, forced with the ERA-Interim reanalysis data, were at 30 km horizontal resolution. The WRF model experiments were initialized on 1 May of each year and integrated until 30 September to cover the entire monsoon season for the years 1982 to 2013. The results indicate that the simulated Indian summer monsoon precipitation and 2 m air temperature are sensitive to the physical parameterization schemes in the WRF model and that choosing the correct combination of physical parameterization schemes is essential for simulating the Indian summer monsoon realistically. Our analysis shows that a model setup with the Kain−Fritsch cumulus scheme, a radiation package with the Dudhia shortwave and Rapid Radiative Transfer Model longwave schemes, the Yonsei State University planetary boundary layer scheme, the WRF Single-Moment 3-class microphysics scheme, the revised MM5 Monin-Obukhov surface layer scheme, and the Unified Noah land surface model is suitable for simulating the precipitation realistically. The model setup with a combination of these physical parameterization schemes was found to have smaller biases and root mean square errors in the simulated precipitation, along with a realistic simulation of intraseasonal and interannual variability of precipitation. The results of this study will be useful to researchers and forecasters using the WRF model to improve the Indian summer monsoon simulations/ forecasts over the Indian region.

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Section: Sensitivity To Cumulus Parameterization Schemessupporting

confidence: 73%

Section: Introductionmentioning

confidence: 99%

Sensitivity of Indian summer monsoon simulation to physical parameterization schemes in the WRF model

et al. 2017

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“…For many decades, however, a number of regional atmosphere modelling studies of the ISM forced with global atmospheric reanalysis has also been conducted with varied success (Bhaskaran et al ., ; Ji and Vernekar, ; VenkataRatnam and Krishna Kumar, ; Dash et al ., ; Saeed et al ., , ; Umakant et al ., ). A reverberating message from many of these studies is that higher resolution of the regional atmospheric model provides a more realistic simulation of the ISM through better representation of the orography, land‐ocean coastlines, vegetation cover, and land use.…”

Section: Introductionmentioning

confidence: 99%

High‐resolution regional‐coupled ocean–atmosphere simulation of the Indian Summer Monsoon

Misra

Mishra

Bhardwaj

2017

Intl Journal of Climatology

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A 23‐year integration of a Regional‐Coupled Ocean–Atmosphere Model (RCOAM) centred over the Indian monsoon region is validated with observations and analysis for its seasonal climatology, evolution, and variability at intraseasonal and interannual scales. The RCOAM has the Regional Spectral Model (RSM) as its atmospheric component and Regional Ocean Model System (ROMS) as its oceanic component. They are both coupled at 15 km grid spacing with identical grids, without applying any form of flux correction and are forced with global fields of atmospheric and oceanic reanalysis. The verification indicates that the RCOAM simulation simulates the mean Indian Summer Monsoon (ISM) rainfall climatology and SST in the neighbouring oceans reasonably well with finer details apparent along the orography (e.g. Western Ghats, Himalaya) and along the upwelling regions of the coastal oceans. In addition the evolution of the ISM at its onset and its devolution around the time of demise in the RCOAM simulation both in the atmosphere and the ocean conform to its well known features and reinforce the coupled ocean–atmosphere phenomenon of the ISM. The intraseasonal variations in the RCOAM simulation also adhere to the observed composite of dry and wet spells of the ISM, with the low‐level flow in the latter (former) counteracting (enhancing) the low‐level atmospheric ISM climatological flow. The interannual variations in relation to the remote ENSO variations are also validated with respect to the observations. It is also shown that the variations of the length of the ISM to the seasonal anomalies of the ISM both in the RCOAM simulation and observations is largely a result of the ENSO teleconnection. However, significant systematic bias in surface fluxes, cloud fraction, SST, and precipitation of the RCOAM simulation of the ISM is also noted.

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“…Although our understanding of ISO and its governing mechanisms have improved in recent times, modeling of ISO still remains a difficult task and many state-of-the-art models perform poorly in simulating the basic structure of ISO (Sabeerali et al, 2013;Sperber et al, 2013). Recently, usage of RCM has increased in view of enhanced representation of orography, coastlines, and land cover among many other factors, which enable better representation of seasonal mean and monsoon variability (Dash et al, 2006;Misra et al, 2018;Raju et al, 2015;Umakanth et al, 2016). Misra et al (2018) investigated the performance of a high-resolution regional coupled ocean-atmosphere climate model and found that the model produces reasonable spatiotemporal structure, propagation characteristics, and amplitude of the ISO as compared to 10.1029/2019JD031648 Table 1 Physics Used in the RCM Simulation…”

Section: Introductionmentioning

confidence: 99%

Differences in Northward Propagation of Convection Over the Arabian Sea and Bay of Bengal During Boreal Summer

Karmakar

Misra

2020

JGR Atmospheres

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The governing dynamics that modulate the propagation characteristics of intraseasonal oscillations (ISO) during summer monsoon over the two ocean basins, Bay of Bengal (BoB) and Arabian Sea (AS), are investigated using observational analysis and high-resolution regional coupled ocean-atmosphere climate model simulations. ISO features are extracted over the Indian region using a data-adaptive spectral method called multichannel singular spectrum analysis. ISO exhibits stronger intensity over the BoB than over the AS. But ISO-filtered rainfall propagates at a faster rate (∼1.25 • /day) over AS as compared to BoB (∼.74 • /day), giving rise to a northwest-southeast tilted band of rainfall anomalies. However, the composite diagrams of several atmospheric fields associated with northward propagation like vorticity, low-level convergence, and oceanic variables like sea surface temperature and mixed layer depth do not show this difference in propagation speed and all exhibit a speed of nearly 0.75 • /day in both the ocean basins. The difference in speed of ISO-filtered rainfall is explained through moisture flux convergence. Anomalous horizontal moisture advection plays a major role over AS in preconditioning the atmosphere and making it favorable for convection. Anomalous wind acting on climatological moisture gradient is the dominant term in the moisture advection equation. Easterly wind anomalies associated with a low-level anticyclone over India helps advect moisture from the eastern side of the domain. The northwest-southeast tilt of ISO is dictated by the atmospheric processes of moisture advection with the upper ocean playing a more passive role in causing the tilt. Key Points: • Intraseasonal oscillations (ISO) in rainfall over the Bay of Bengal (BoB) propagate at a slower rate than over the Arabian Sea (AS) • Differential atmospheric moisture flux convergence between BoB and AS determines the tilted structure of ISO • The upper ocean in BoB and AS plays a more passive role in the tilt of the ISO Correspondence to:

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Representation of monsoon intraseasonal oscillations in regional climate model: sensitivity to convective physics

Cited by 27 publications

References 66 publications

Sensitivity of Indian summer monsoon simulation to physical parameterization schemes in the WRF model

Sensitivity of Indian summer monsoon simulation to physical parameterization schemes in the WRF model

High‐resolution regional‐coupled ocean–atmosphere simulation of the Indian Summer Monsoon

Differences in Northward Propagation of Convection Over the Arabian Sea and Bay of Bengal During Boreal Summer

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