Assessment of WRF model parameter sensitivity for high‐intensity precipitation events during the Indian summer monsoon

Abstract. Simulations of the Indian summer monsoon by cloud-permitting WRF model at gray zone resolution are described in this study, with a particular emphasis on the model ability to capture the Monsoon Intraseasonal Oscillations (MISO). Five boreal summers are simulated from 2007 to 2011 using the ERA-Interim reanalysis as lateral boundary forcing data. Our experimental set-up relies on a high horizontal resolution of 9 km to capture deep convection without the use of a cumulus parameterization. When compared to simulations with coarser grid spacing (27-km) and using the cumulus scheme, our approach results in a reduction of the biases in mean precipitation and in more realistic reproduction of the low frequency variability associated with MISO. Results show that the model at gray zone resolution captures the fundamental features of the summer monsoon. The spatial distributions and temporal evolutions of monsoon rainfall in WRF simulations are verified qualitatively well against observations from the Tropical Rainfall Measurement Mission (TRMM), with regional maxima located over West Ghats, central India, Himalaya foothills and the west coast of Myanmar. The onset, breaks and withdrawal of the summer monsoon in each year are also realistically captured by the model. MISO phase composites of monsoon rainfall, low-level wind and precipitable water anomalies in the simulations are compared qualitatively with the observations. Both the simulations and observations show a northeastward propagation of the MISO, with the intensification and weakening of Somali Jet over the Arabian Sea during the active and break phases of the Indian summer monsoon.

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Calibration of WRF model parameters using multiobjective adaptive surrogate model-based optimization to improve the prediction of the Indian summer monsoon

Climate Dynamics ◽

10.1007/s00382-020-05288-1 ◽

2020 ◽

Vol 55 (3-4) ◽

pp. 631-650

Author(s):

Sandeep Chinta ◽

C. Balaji

Keyword(s):

Summer Monsoon ◽

Indian Summer Monsoon ◽

Surrogate Model ◽

Wrf Model ◽

Model Parameters ◽

Model Based

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Regional simulation of Indian summer monsoon intraseasonal oscillations at gray-zone resolution

Atmospheric Chemistry and Physics ◽

10.5194/acp-18-1003-2018 ◽

2018 ◽

Vol 18 (2) ◽

pp. 1003-1022 ◽

Cited By ~ 14

Author(s):

Xingchao Chen ◽

Olivier M. Pauluis ◽

Fuqing Zhang

Keyword(s):

Summer Monsoon ◽

Indian Summer Monsoon ◽

Monsoon Rainfall ◽

Deep Convection ◽

Wrf Model ◽

Central India ◽

Precipitable Water ◽

Gray Zone ◽

Grid Spacing ◽

Intraseasonal Oscillations

Abstract. Simulations of the Indian summer monsoon by the cloud-permitting Weather Research and Forecasting (WRF) model at gray-zone resolution are described in this study, with a particular emphasis on the model ability to capture the monsoon intraseasonal oscillations (MISOs). Five boreal summers are simulated from 2007 to 2011 using the ERA-Interim reanalysis as the lateral boundary forcing data. Our experimental setup relies on a horizontal grid spacing of 9 km to explicitly simulate deep convection without the use of cumulus parameterizations. When compared to simulations with coarser grid spacing (27 km) and using a cumulus scheme, the 9 km simulations reduce the biases in mean precipitation and produce more realistic low-frequency variability associated with MISOs. Results show that the model at the 9 km gray-zone resolution captures the salient features of the summer monsoon. The spatial distributions and temporal evolutions of monsoon rainfall in the WRF simulations verify qualitatively well against observations from the Tropical Rainfall Measurement Mission (TRMM), with regional maxima located over Western Ghats, central India, Himalaya foothills, and the west coast of Myanmar. The onset, breaks, and withdrawal of the summer monsoon in each year are also realistically captured by the model. The MISO-phase composites of monsoon rainfall, low-level wind, and precipitable water anomalies in the simulations also agree qualitatively with the observations. Both the simulations and observations show a northeastward propagation of the MISOs, with the intensification and weakening of the Somali Jet over the Arabian Sea during the active and break phases of the Indian summer monsoon.

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Inter-Comparison of Two Regional Climate Models (RegCM and WRF) in Downscaling CFSv2 For the Seasonal Prediction of Indian Summer Monsoon

10.21203/rs.3.rs-1059274/v1 ◽

2021 ◽

Author(s):

Manas Ranjan Mohanty ◽

Uma Charan Mohanty

Keyword(s):

Summer Monsoon ◽

Indian Summer Monsoon ◽

Climate Models ◽

Dynamical Downscaling ◽

Regional Climate ◽

Wrf Model ◽

Daily Rainfall ◽

Regional Climate Models ◽

Regional Models ◽

Vertical Column

Abstract The efficacy of two latest versions of regional climate models (RegCM and WRF) for simulating the Indian summer monsoon (JJAS) is tested in this study. The CFSv2 hindcast outputs are downscaled over the Indian monsoon domain for 11 contrasting monsoon seasons using the regional models. The April start ensembles of the CFSv2 are averaged to generate the initial and lateral boundary conditions for driving the WRF and RegCM. The regional models perform better in simulating the Indian summer monsoon features better than the parent CFSv2 model. The rainfall pattern as well as the intensities are improved with the dynamical downscaling and the errors in the rainfall are minimized over the GCM hindcast. On comparing the two regional models, the RegCM overestimates the rainfall during the excess and normal monsoon seasons. The RCMs improve the skill of rainfall prediction as compared to the GCM and WRF shows better skill in particular. One peculiar finding of this study is that the daily rainfall biases averaged over all the years of simulation shows that the two RCMs show similar biases with RegCM showing stronger biases occasionally. It may be implied that the errors from GCM in the form of the ICBC might be influencing the simulation in the RCMs. The upper air and surface parameters analysis shows that the WRF performs better in representing the semi-permanent features of the Indian summer monsoon which may be helping in improving the rainfall over the RegCM. The wind pattern as well as the relative humidity along the vertical column of the atmosphere are captured better in the WRF model. Diagnostics of CAPE & vertically integrated moisture transport supports the finding of the rainfall being simulated better in the WRF model.

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