Browsing by Author "Jai-Ho Oh"

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Correction to: Projection of seasonal summer precipitation over Indian sub-continent with a high-resolution AGCM based on the RCP scenarios (Meteorology and Atmospheric Physics, (2019), 131, 4, (897-916), 10.1007/s00703-018-0612-7)
(Springer-Verlag Wien, 2019) Sumin Woo; Gyan Prakash Singh; Jai-Ho Oh; Kyoung-Min Lee
The authors would like to include the below text in the acknowledgement section of the Original Publication. Acknowledgements The authors want to acknowledge the Korea Meteorological Administration research and Development Program under Grant KMI 2018-07910. We also want to acknowledge the Global Science experimental Data hub Center (GSDC) Project, Korea Institute of Science and Technology Information (KISTI) for using computing resources. © 2018, Springer-Verlag GmbH Austria, part of Springer Nature.
Impact of Indian Ocean sea-surface temperature anomaly on Indian summer monsoon precipitation using a regional climate model
(2007) G.P. Singh; Jai-Ho Oh
The present study uses a recent version (Version-III) of National Center for Atmospheric Research (NCAR) Regional Climate Model (RegCM3) to simulate the Indian summer monsoon rainfall (ISMR). Since RegCM3 is used for the first time for such a study over south Asia, its performance was tested for different conditions of ISMR. The RegCM3 is integrated at 60 km horizontal resolution from April 1 to October 1 for three contrasting rain years corresponding to drought (2002), normal (2001) and excess (1994). The monsoon circulation features simulated by the RegCM3 are compared with those of the National Center for Environmental Prediction (NCEP)/NCAR reanalysis, and simulated precipitation is validated against observations from the Global Precipitation Climatology Centre (GPCC) data sets. Validation of the wind patterns at lower and upper levels shows that the RegCM3 simulated results are close to the NCEP/NCAR reanalysis. Similarly, the patterns of precipitation distribution simulated by the RegCM3 are close to the GPCC (except over the west coast). Features of intra-seasonal oscillation during different rain years are also examined by applying a frequency filter and the technique of wavelet analysis to rainfall data. Results indicate that a faster (10-20 days) mode dominated during an excess rain year and a slower (30-60 days) mode during a deficient rain year, which agree well with the observations (GPCC). The influence of increase in sea-surface temperature (SST) by 0.6°C on the following summer monsoon circulation and rainfall over India has also been studied. The SST (warm) experiments show that the regional warming of SST over the Indian Ocean enhanced the monsoon precipitation mainly over south peninsular India, west peninsular India and the Indian Ocean and reduced precipitation over northeast India. Copyright © 2007 Royal Meteorological Society.
Possible teleconnections between East and South Asian summer monsoon precipitation in projected future climate change
(Springer-Verlag Wien, 2019) Sumin Woo; Gyan Prakash Singh; Jai-Ho Oh; Kyoung-Min Lee
The present paper examined the teleconnections between two huge Asian summer monsoon components (South and East Asia) during three time slices in future: near-(2010–2039), mid-(2040–2069) and far-(2070–2100) futures under the RCP4.5 and RCP8.5 scenarios. For this purpose, a high-resolution atmospheric general circulation model is used and integrated at 40 km horizontal resolution. To get more insight into the relationships between the two Asian monsoon components, we have studied the spatial displaying correlation coefficients (CCs) pattern of precipitation over the entire Asian monsoon region with that of South Asia and three regions of East Asia (North China, Korea–Japan and Southern China) separately during the same three time slices. The possible factors responsible for these teleconnections are explored by using mean sea level pressure (MSLP) and wind fields at 850 hPa. The CC pattern of precipitation over South Asia shows an in-phase relationship with North China and an out-of-phase relationship with Korea–Japan, while precipitation variations over Korea–Japan and Southern China exhibit an out-of-phase relationship with South Asia. The CCs analysis between the two Asian blocks during different time slices shows the strongest CCs during the near and far future with the RCP8.5 scenario. The CC pattern of precipitation over Korea–Japan and Southern China with the wind (at 850 hPa) and MSLP fields indicate that the major parts of the moisture over Korea–Japan gets transported from the west Pacific along the western limb of NPSH, while the moisture over Southern China comes from the Bay of Bengal and South China Seas for good monsoon activity. © 2018, The Author(s).
Projected changes in summer precipitation over East Asia with a high-resolution atmospheric general circulation model during 21st century
(John Wiley and Sons Ltd, 2018) Sumin Woo; Gyan Prakash Singh; Jai-Ho Oh; Kyoung-Min Lee
We provide a broad view of East Asian summer monsoon (EASM) precipitation and their changes in the 21st century under the representative concentration pathway RCP4.5 and RCP8.5 scenarios using a high-resolution (at 40 km) atmospheric general circulation model (AGCM). The simulated fields are validated against the multiple observational data sets in the reference period (1979–2008). Validation of seasonal simulated global climatology and EASM precipitation, annual cycle and various circulation fields including 25 individual Coupled Model Intercomparison Project phase 5 (CMIP5) and CMIP5 MME suggests that AGCM can be used to study the future projected characteristics of EASM. An investigation of uncertainty in precipitation shows larger values in the regions of high-precipitation belt and low terrain. Future projections are categorized as near (2010–2039), mid (2040–2069) and far (2070–2100) futures. The model projects an increased summer precipitation of about 3.2% (2.3%) in near future, about 4.5% (4.5%) in mid-future and about 2.4% (2.3%) in far future over East Asia region under RCP4.5 (RCP8.5) scenarios when compared to the reference period. As far as regional landmasses are concerned, model projects a gradual increase in the range of 5–15% over northeast China, coastal regions of southern China, Korea and Japan regions and a decrease of about 5–10% over southeastern and northwest parts of East Asia during the 21st century. The projected increase of EASM can be attributed to an increase in atmospheric moistures (relative humidity) over the east coast of China, Korea and northeast China and north and northwestwards enhancement of eddy geopotential height. Extreme events are examined by using various precipitation indices over EASM regions. Results indicate that the indices of heavy precipitation are projected to increase (both frequency and intensity) over Korea, Japan and northeast China in the range of 5–20%, indicating strong sensitivity of EASM to global warming. © 2018 The Authors. International Journal of Climatology published by John Wiley & Sons Ltd on behalf of the Royal Meteorological Society.
Projection of seasonal summer precipitation over Indian sub-continent with a high-resolution AGCM based on the RCP scenarios
(Springer-Verlag Wien, 2019) Sumin Woo; Gyan Prakash Singh; Jai-Ho Oh; Kyoung-Min Lee
Seasonal changes in precipitation characteristics over India were projected using a high-resolution (40-km) atmospheric general circulation model (AGCM) during the near- (2010–2039), mid- (2040–2069), and far- (2070–2099) futures. For the model evaluation, we simulated an Atmospheric Model Intercomparison Project-type present-day climate using AGCM with observed sea-surface temperature and sea-ice concentration. Based on this simulation, we have simulated the current climate from 1979 to 2009 and subsequently the future climate projection until 2100 using a CMCC-CM model from Coupled Model Intercomparison Project phase 5 models based on RCP4.5 and RCP8.5 scenarios. Using various observed precipitation data, the validation of the simulated precipitation indicates that the AGCM well-captured the high and low rain belts and also onset and withdrawal of monsoon in the present-day climate simulation. Future projections were performed for the above-mentioned time slices (near-, mid-, and far futures). The model projected an increase in summer precipitation from 7 to 18% under RCP4.5 and from 14 to 18% under RCP8.5 from the mid- to far futures. Projected summer precipitation from different time slices depicts an increase over northwest (NWI) and west-south peninsular India (SPI) and a reduction over northeast and north-central India. The model projected an eastward shift of monsoon trough around 2° longitude and expansion and intensification of Mascarene High and Tibetan High seems to be associated with projected precipitation. The model projected extreme precipitation events show an increase (20–50%) in rainy days over NWI and SPI. While a significant increase of about 20–50% is noticed in heavy rain events over SPI during the far future. © 2018, The Author(s).
Sensitivity of summer monsoon precipitation over East Asia to convective parameterization schemes in RegCM3
(Meteorological Society of Japan, 2006) G.P. Singh; Jai-Ho Oh; Jin-Young Kim; Ok-Yeon Kim
This study investigates some of the important characteristics of summer monsoon circulation and precipitation over East Asia in general and Korea in particular using the recent version of NCAR Regional Climate Model (RegCM3). RegCM3 has been integrated at 27 km horizontal resolution over the East Asian domain for the period from 1998 to 2002 (5 years). The important characteristics of temperature and wind at upper and lower levels and precipitation simulated by the RegCM3 over South Korea are examined in detail using different convective parameterization schemes namely, mass flux schemes, a simplified Kuo-type scheme and Emanuel (EMU) scheme. The monsoon circulation features (wind and temperature) simulated by RegCM3 are compared with those of the NCEP/NCAR reanalysis (Kalnay et al. 1996) and simulated summer precipitation in JJA (average of June to August) over Korea (KMR) is validated against the observation from Korea Meteorological Administration (KMA). Validation of simulated precipitation with KMA shows that the use of the Arakawa and Schubert (AS) and EMU convection schemes are more close to the KMA. The statistical analysis (area average precipitation, standard deviation and correlation analysis) also indicates that the use of EMU and AS schemes perform better over East Asia particularly over Korea. © 2006, the Meteorological Society of Japan.
Simulation Korean summer monsoon rainfall with NCAR regional climate model
(World Scientific Publishing Co., 2006) G.P. Singh; Jai-Ho Oh; Jin-Young Kim
Some of the important characteristics of Korean summer monsoon circulations and rainfall are examined using the NCAR Regional Climate Model (RegCM3). RegCM3 has been simulated at 27 km horizontal resolution over the east Asia domain for the period from January to December in 2002. The important features of wind and temperature at lower and upper levels over east Asia and precipitation simulated by the model over South Korea are examined in details for different convective parameterization schemes namely, mass flux, a Kuo-type and Emanuel schemes. The monsoon circulation features simulated with RegCM3 are compared with those of the NCEP/NCAR reanalysis and the simulated Korean summer monsoon rainfall (KMR) is validated against the observations from Korea Meteorological Administration (KMA). Validation of simulated precipitation with KMA shows that the use of the Emanuel scheme is more close to the KMA. Characteristic features of the intra-seasonal quasi-biweekly (10-20 days period) and the Madden-Julian (30-60 days period) oscillations have been investigated. Results of intra-seasonal oscillation also indicate that the use of Emanuel convective scheme yields results close to the KMA. Results from wavelet analysis show that the high precipitation in 2002 may be associated with prominent 30-60 days oscillation during the month of August. © 2006 by World Scientific Publishing Co. Pte. Ltd. All rights reserved.
Simulation of record rainfall event over Mumbai on 26 July, 2005
(World Scientific Publishing Co., 2010) G.P. Singh; Jai-Ho Oh; H.K. Chaudhary
The Santa Cruz observatory at Mumbai airport recorded a very heavy precipitation of 94.4 cm (in less than 24 hours) on 26 July 2005. The country important commercial city came to a complete standstill due to severe flooding. This flooding situation caused a severe damage of life and poverty. The Financial Times and Economics Times news on 4 August 2005 have reported that the number of dead in the Maharashtra floods could well be above 1000 and around Rs. 5000 crores estimated loss in the state. We have simulated a case of extremely high precipitation using a National Centre for Atmospheric Research regional climate model (RegCM3) at 20km horizontal resolution. Results indicate that the model captures well the well-marked cyclonic circulation (low) and the simulated precipitation is more close to observed value of precipitation when FC, KUO and AS convective cumulus parametrizations schemes are used. © 2010 by World Scientific Publishing Co. Pte. Ltd. All rights reserved.
Tropical circulation indices and performances of Indian summer monsoon rainfall
(World Scientific Publishing Co., 2009) G.P. Singh; Jai-Ho Oh; S.N. Pandey; R. Bhatla
The interannual relationships between the summer monsoon rainfall over all India (AIR), northwest India (NWR), and peninsular India (PIR), and seven different tropical circulation indices (TCIs) (based on mean sea level pressure) over five selected tropical stations, three over the Indian Ocean namely Agalega (A), Cocos Island (C), Il-Nouvelle (I), and two over the land stations namely New Delhi (N) and Malacol (M) have been examined for 30 years’ period (1953-1982). The names of the indices are (i) TCI (A-M), (ii) TCI (A-N), (iii) TCI (A-C), (iv) TCI (C-M), (v) TCI (C-N), (vi) TCI (I-N), and (vii) TCI (I-M). The results indicate that significant strong and inverse relationships exist between (a) TCI (C-M) of concurrent August and AIR, NWR, and PIR, (b) TCI (C-N) of antecedent February and AIR, NWR, and PIR and (c) TCI (I-N) of antecedent May shows significant and direct association with AIR and PIR. Stability analysis of different TCIs shows that TCI (C-M) of concurrent August and TCI (C-N) of antecedent February show consistently significant relationship over the successive 25 years’ period. © 2009 by World Scientific Publishing Co. Pte. Ltd. All rights reserved.