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All Abstracts of Session AS08

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Oral Presentations

AS08 - Cmip6 and CORDEX Climate Model Improvements
Tuesday, August 02, 2016 | 309B (L3N) | 14:00-15:30
1.
AS08-D2-PM1-309B(L3N)-001 (AS08-A008)
 
On the Systematic Errors in Cloud Simulation by MIROC6
Tomoo OGURA1#+, Hiroaki TATEBE2, Youichi KAMAE3,4, Masahiro WATANABE5, Masahide KIMOTO5
1 National Institute for Environmental Studies, Japan, 2 Japan Agency for Marine-Earth Science and Technology, Japan, 3 University of Tsukuba, Japan, 4 University of California, San Diego, United States, 5 The University of Tokyo, Japan
#Corresponding author: ogura@nies.go.jp +Presenter

Systematic errors in clouds simulated by climate models are relevant to cloud feedback and climate change projection by the models. To alleviate such errors and increase confidence in the future projection, version 6 of the climate model MIROC has been developed for the CMIP6 simulations. The development includes increasing the model top height from 3.0 to 0.004hPa, and implementing a shallow convection parameterization. Pre-industrial control simulation by the MIROC6 shows some improvements compared to the one by the CMIP5 version, MIROC5, such as decrease in dry bias in the lower troposphere, and decrease in overestimation of low-top clouds. At the meeting, we will discuss potential impact of such improvements on the future projections by MIROC6, and also the remaining issues in the cloud simulation.

2.
AS08-D2-PM1-309B(L3N)-002 (AS08-A001)
 
Fourteen-Year Long AIRS Tropospheric Temperature and Humidity Profile Data Records and Their Use in Climate Model Evaluation and Analysis
Baijun TIAN1,2#+
1 Jet Propulsion Laboratory, United States, 2 University of California, Los Angeles, United States
#Corresponding author: Baijun.Tian@jpl.nasa.gov +Presenter

The Atmospheric Infrared Sounder/Advanced Sounding Unit-A (AIRS/AMSU-A) is the primary tropospheric temperature and moisture sounding unit on NASA’s Aqua satellite. With unprecedented infrared spectral resolution, the AIRS/AMSU-A measures the vertical profiles of temperature and moisture (both specific and relative humidity) in the Earth's troposphere with high vertical (~2 km), horizontal (~45 km at nadir), and temporal (twice daily) resolutions and global coverage. The AIRS/AMSU-A has now provided about fourteen-year long high-quality tropospheric temperature and moisture profile data. In this talk, I will discuss this fourteen-year-long AIRS/AMSU-A tropospheric temperature and humidity data records and their use in the climate model evaluation and analysis. As an example, I will highlight the AIRS Obs4MIPs dataset we have produced (Tian et al., 2013) and their use in the CMIP3/5 climate model evaluation. The tropospheric temperature and moisture biases in CMIP3/5 climate models, especially the double-ITCZ bias and its role as an emergent constraint for equilibrium climate sensitivity, will be discussed (Tian et al., 2013; Tian, 2015). I will also discuss the possible role of the AIRS data in the CMIP6 climate model evaluation. In addition, I will also discuss the AIRS climatology products we are working on and their potential use in climate model evaluation and analysis.

3.
AS08-D2-PM1-309B(L3N)-003 (AS08-A002)
 
Evaluation of CMIP5 and NASA GISS Post-CMIP5 Simulated Clouds and TOA Radiation Budgets Using NASA Satellite Observations
Xiquan DONG#+
University of North Dakota, United States
#Corresponding author: dong@aero.und.edu +Presenter

Although many improvements have been made to the Global Circulation Models (GCMs) involved in the CMIP5 project, clouds and their radiative feedbacks are still a problem. In this study, the simulated total cloud fraction (CF), cloud water path (CWP), TOA radiation budgets and cloud radiative forcings (CRFs) from 28 CMIP5 AMIP models are evaluated and compared with multiple satellite observations from CERES, MODIS, ISCCP, CloudSat, and CALIPSO. The multimodel ensemble mean CF (57.6%) is, on average, underestimated by nearly 8% (between 65 °N/S) when compared to CERES-MODIS (CM) and ISCCP results while an even larger negative bias (17.1%) exists compared to the CloudSat/CALIPSO results.  CWP bias is similar in comparison to the CF results, with a negative bias of 16.1 gm−2 compared to CM CWP.  The model simulated and CERES EBAF observed TOA reflected SW and OLR fluxes on average differ by 1.8 Wm−2 and −0.9 Wm−2, respectively. The averaged SW, LW, and net CRFs from CERES EBAF are −50.1, 27.6, and −22.5 Wm−2, respectively, indicating a net cooling effect of clouds on the TOA radiation budget. The differences in SW and LW CRFs between observations and the multimodel ensemble means are only −1.3 Wm−2 and −1.6 Wm−2, respectively, resulting in a larger net cooling effect of 2.9 Wm−2 in the model simulations.

Furthermore, the NASA GISS CMIP5 (C5) and Post-CMIP5 (P5) simulated cloud properties and TOA radiation budgets and CREs were assessed utilizing multiple satellite observations and CERES EBAF-TOA results. Comparisons revealed that the P5 and C5-simulated global means of clear-sky and all-sky outgoing longwave radiation (OLR) match well with CERES observations, while biases are observed regionally. Negative biases are found in both P5 and C5-simulated clear-sky OLR. P5-simulated all-sky albedo slightly increased over the SMLs due to the increase in low-level cloud fraction from the new planetary boundary layer (PBL) scheme. SW, LW, and net CRE are quantitatively analyzed as well. The comparisons and statistical results from this study may provide helpful insight for improving GCM simulations of clouds and TOA radiation budgets in future versions of CMIP.

4.
AS08-D2-PM1-309B(L3N)-004 (AS08-A004)
 
Evaluating Climate Models Using Clouds and the Earth’s Radiant Energy System (CERES) Data Products
Norman LOEB1#+, Zachary EITZEN2, Moguo SUN2, David DOELLING1
1 NASA Langley Research Center, United States, 2 Science Systems and Applications, Inc., United States
#Corresponding author: norman.g.loeb@nasa.gov +Presenter

The Clouds and the Earth’s Radiant Energy System (CERES) provides observations of Earth’s radiation budget (ERB) at the top-of-atmosphere (TOA), within the atmosphere and at the surface together with the associated cloud and aerosol properties over time scales ranging from hourly to monthly and spatial scales ranging from footprint level (~20 km) to global. A blended science team comprised of instrument engineers, remote sensing experts, and prominent members of the climate modeling community conceived the CERES data products. As such, the CERES data products are tailored to be highly useful for climate model evaluation both during the model development phase and during the post-CMIP evaluation period.

A key advance of CERES over previous ERB datasets is that CERES extensively uses coincident higher spatial resolution spectral imager measurements on both low-Earth orbit and geostationary platforms. These instruments enable a host of other variables describing cloud, aerosol and surface properties to be retrieved alongside CERES radiative fluxes. Importantly, the CERES data products account for the regional and global diurnal cycle of radiative fluxes.

This presentation will describe how CERES data products have commonly been used to evaluate climate model output. We also introduce a new effort involving a CERES flux-by-cloud type simulator applied to 3-hourly model output that enables direct comparisons with the new CERES FluxByCloudTyp data product, which provides instantaneous CERES TOA fluxes by region and cloud type. This simulator and CERES FluxByCloudTyp product have the potential to identify shortcomings in specific model parameterizations (e.g., boundary-layer parameterizations, convective clouds, processes that affect surface albedo) and can quantify the radiative impact of cloud model biases.

5.
AS08-D2-PM1-309B(L3N)-005 (AS08-A005)
 
Relationships Between Tropical High Clouds, Circulation and Precipitation
Hui SU#+, Jonathan JIANG
California Institute of Technology, United States
#Corresponding author: Hui.Su@jpl.nasa.gov +Presenter

Climate model projections of hydrological sensitivity, i.e., the rate of global mean precipitation change per degree of surface warming, vary from 1.0%/K to 3.0%/K. Such a large inter-model spread in precipitation sensitivity occurs even in present-day simulations that are driven by observed sea surface temperature. By analyzing 22 climate model simulations that participated in the Coupled Model Inter-comparison Project Phase 5 (CMIP5), we find that the inter-model spread in the inter-annual sensitivity of tropical mean precipitation to surface temperature is highly correlated with that of the tropical-mean high cloud fraction, which is directly linked to atmospheric longwave radiative cooling capability. The models that simulate a stronger decrease of tropical mean high cloud fraction with surface warming tend to have greater precipitation sensitivity primarily owing to the greater loss of longwave radiation at the top-of-atmosphere. As the interannual variations of tropical high cloud fraction are strongly coupled with atmospheric circulation change, we argue that the discrepancy in model representation of large-scale circulation sensitivity to surface warming has significant bearing on the inter-model spread in simulations of precipitation change.

6.
AS08-D2-PM1-309B(L3N)-006 (AS08-A007)
 
An Assessment of Upper-Troposphere and Lower-Stratosphere Water Vapor in MERRA, MERRA2 and ECMWF Reanalyses Using Aura MLS Observations
Jonathan JIANG#+, Hui SU
California Institute of Technology, United States
#Corresponding author: Jonathan.H.Jiang@jpl.nasa.gov +Presenter

Global water vapor (H2O) measurements from Microwave Limb Sounder (MLS) are used to evaluate upper tropospheric (UT) and lower stratospheric (LS) H2O products produced by NASA Modern-Era Retrospective Analysis for Research and Applications (MERRA), its newest release MERRA2, and European Centre for Medium-Range Weather Forecasts (ECMWF) Interim Reanalyses. Focusing on the H2O amount and transport from UT to LS, we show that all reanalyses overestimate annual global mean UT H2O by up to ~150% compared to MLS observations. Substantial differences in H2O transport are also found between the observations and reanalyses. Vertically, H2O transport across the tropical tropopause (16-20km) in the reanalyses is faster by up to ~86% compared to MLS observations. In the tropical LS (21-25 km), the mean vertical transport from ECMWF is 168% faster than the MLS estimate, while MERRA and MERRA2 have vertical transport velocities within 10% of MLS values. Horizontally at 100 hPa, both observation and reanalyses show faster poleward transport in the Northern Hemisphere (NH) than in the Southern Hemisphere (SH). Compared to MLS observations, the H2O horizontal transport for both MERRA and MERRA2 are 106% faster in the NH, but about 42-45% slower in the SH. ECMWF horizontal transport is 16% faster than MLS observations in both hemispheres. The ratio of northward to southward transport velocities for ECMWF is 1.4, which agrees with MLS observation while the corresponding ratios for MERRA and MERRA2 are about 3.5 times larger.

AS08 - Cmip6 and CORDEX Climate Model Improvements
Tuesday, August 02, 2016 | 309B (L3N) | 16:00-18:00
1.
AS08-D2-PM2-309B(L3N)-007 (AS08-A017)
 
Poleward Propagation of Convection During Boreal Summer in CMIP5 Model Projections
Arindam CHAKRABORTY#+, Ravi NANJUNDIAH, Gaurav SRIVASTAVA
Indian Institute of Science, India
#Corresponding author: arch@caos.iisc.ernet.in +Presenter

Low-frequency intraseasonal oscillation over south Asia, manifested by northward propagation of convection, results in active-break cycle and modulates the seasonal mean rainfall. Since there is much debate about the projected changes in the characteristics of Indian summer monsoon rainfall, it is necessary to understand the intensity and spatial scale of such oscillatory systems. In this study we used wavelet method to quantify the spatial scale of propagation of convection. In addition, intensity and associated time period are also obtained from the analysis. In this paper, a detailed account of the changing nature of these quantities with different climate projections is presented.

2.
AS08-D2-PM2-309B(L3N)-008 (AS08-A018)
 
Cloud Parameterization and its Impact in Beijing Climate Center Climate System Model
Tongwen WU#+, Li ZHANG, Yixiong LU, Weihua JIE
China Meteorological Administration, China
#Corresponding author: twwu@cma.gov.cn +Presenter

Cloud parameterization in climate models is an issue that needs to explore. A new parameterization scheme to estimate convective cloud amounts is suggested. It is determined by the water vapor mixing ratio and temperature in the ‘environment’ and “convection cloud package” and their variations. This scheme is used for Beijing Climate Center Climate System Model versions that are used for CMIP6 experiments. With contrast to the previous scheme that is suggested by Xu and Krueger (1991), it not only improves the simulations of cloud amount, but also shortwave and longwave radiation forcings of cloud.

3.
AS08-D2-PM2-309B(L3N)-009 (AS08-A013)
 
Near-Linear Response of Mean Monsoon Strength to a Broad Range of Radiative Forcings
William BOOS#+, Trude STORELVMO
Yale University, United States
#Corresponding author: william.boos@yale.edu +Presenter

Previous theoretical models have been used to argue that seasonal mean monsoons will shift abruptly and discontinuously from wet to dry stable states as their radiative forcings pass a critical threshold, sometimes referred to as a "tipping point". Further support for a strongly nonlinear response of monsoons to radiative forcings is found in the seasonal onset of the South Asian summer monsoon, which is abrupt compared to the annual cycle of insolation. Here it is shown that the seasonal mean strength of monsoons instead exhibits a nearly linear dependence on a wide range of radiative forcings. First, a previous theory that predicted a discontinuous, threshold response is shown to omit a dominant stabilizing term in the equations of motion; a corrected theory predicts a continuous and nearly linear response of seasonal mean monsoon strength to forcings. A comprehensive global climate model is then used to show that the seasonal mean South Asian monsoon exhibits a near-linear dependence on a wide range of isolated greenhouse gas, aerosol, and surface albedo forcings. This model reproduces the observed abrupt seasonal onset of the South Asian monsoon but produces a near-linear response of the mean monsoon by changing the duration of the summer circulation and the latitude of that circulation's ascent branch. Thus, neither a physically correct theoretical model nor a comprehensive climate model support the idea that seasonal mean monsoons will undergo abrupt, nonlinear shifts in response to changes in greenhouse gas concentrations, aerosol emissions, or land surface albedo.

4.
AS08-D2-PM2-309B(L3N)-010 (AS08-A014)
 
Future Changes of the Monsoon Precipitation by CMIP5 Models and High-Resolution MRI-AGCM Ensemble Simulations
Akio KITOH1#+, Hirokazu ENDO2
1 University of Tsukuba, Japan, 2 Japan Meteorological Agency, Japan
#Corresponding author: kito.akio.ff@u.tsukuba.ac.jp +Presenter

This study investigates future changes in the summer monsoon precipitation based on recent studies that include analysis of the state-of-the-art CMIP5 model simulations together with projections of extremes and regional-scale climate from high-resolution global atmospheric models (MRI-AGCMs). The CMIP5 models project that both the amount and intensity of the Asian summer monsoon precipitation are likely to increase under global warming, and that the rate of increase will be higher than that in other monsoon regions. Changes in hydrologic cycle can be divided into the thermodynamic effect and the dynamic effect. For global monsoon precipitation changes, the thermodynamic effect (enhanced moisture flux convergence due to increased moisture) is dominant, partly compensated by the dynamic effect (less wind convergence). Relative role of the two effects is different from region to region. In the most regional monsoons, the dynamic effect mostly compensates the thermodynamic effect. However in the Asian monsoon region, the dynamic effect is smaller than other monsoon regions, resulting in large increase in monsoon precipitation. Next, ensemble time-slice experiments using 20-km and 60-km mesh MRI-AGCMs are analyzed. In the present-day simulations, the models’ skills outperform those of CMIP5 models. The ensemble projections with multi-SSTs and multi-physics show an increase in precipitation over most monsoon regions, especially in its extremes, but there are large uncertainties in the magnitude of their changes. The source of these uncertainties is assessed.

5.
AS08-D2-PM2-309B(L3N)-011 (AS08-A016)
 
Indian Summer Monsoon and its Projection Based on RegCM Cordex Simulations
Sushil Kumar DASH#+
Indian Institute of Technology Delhi, India
#Corresponding author: skdash@cas.iitd.ernet.in +Presenter

Observational study based on the weakening of the lower level monsoon westerly and decrease in the number of monsoon depressions indicate that the Indian summer monsoon circulation has been weakening. It is also found that although the mean summer monsoon rainfall over India has not changed much, there is increase in the occurrence of short duration heavy rain events and decrease in the longer duration moderate rainfall events. In this study, the seasonal mean summer monsoon over India has been examined using the regional model RegCM CORDEX simulations over the South Asia domain. Here, the state-of-the-art version 4 of RegCM has been integrated from 1970 to 2099 at 50 km horizontal resolution driven by the global model GFDL-ESM2M. The simulated mean summer monsoon circulation and associated rainfall by RegCM4 are validated against the observed values in the reference period 1975 to 2004 based on GPCP and IMD data sets. Regional model results are also compared with those of the global model GFDL which forces RegCM4. Future projections are categorized as near-future (2010-2039), mid-future (2040-2069) and far-future (2070-2099). Comparison of projected seasonal (June-Sept) mean rainfall from the different time slices indicate gradual increase in the intensity of changes over some of the regions under both the scenarios RCP4.5 and 8.5. RegCM4 projected rainfall over most of the Indian land mass and equatorial and northern India Ocean decreases and on the contrary it increases over the Arabian Sea, northern Bay of Bengal and the Himalayas. Results show that the monsoon circulation may become weaker in the future, associated with decrease in rainfall over Indian land points. The RegCM4 projected decrease in JJAS rainfall under RCP8.5 scenario over the central, eastern and peninsular India by the end of the century is in the range of 25-40% of their mean reference period values significant at 5% level. This talk will also project the changes in temperature and rainfall extremes based RegCM CORDEX simulation.

6.
AS08-D2-PM2-309B(L3N)-012 (AS08-A010)
 
Indian Monsoon Simulation in CMIP5 Models
Abhishek ANAND#+, Saroj Kanta MISHRA, Sandeep SAHANY, T. Chanakya Vishwanath REDDY
Indian Institute of Technology Delhi, India
#Corresponding author: abhipat.13@gmail.com +Presenter

The mystery of Indian summer monsoon is less understood and has become more challenging in recent decades due to impacts of global climate change. To understand past and future projections of Indian summer monsoon, the numerical simulations of monsoon and climate system for historical and different warming scenario are produced by coupled model inter-comparison project (CMIP). This paper evaluates the performance of 28 CMIP5-copuled atmosphere-ocean general circulation models in their representation of southwest Monsoon. The analysis of Somali jet, temperature at 2m height and mean JJAS precipitation along with NCEP reanalysis products are done for the period of 1975-2005 for region between 45 N to 20 S and 40 E to 120 E. The analysis of models suggest large inter-model systematic biases. However, most models show small bias for Somali jet and air temperature at 2 m height and large biases for precipitation in CMIP5 models. The models like CCSM4, MIROC4h, CESM-CAM5, GFDL-CM3 and HadCM3 perform well with low biases although the models need further improvement for better simulation of southwest Monsoon.

Poster Presentations

  AS08-D3-PM2-P-013 (AS08-A003)
 
A Single Ice Stratiform Cloud Microphysics Scheme in the Community Atmosphere Model
Xi ZHAO1#+, Yanluan LIN1, Bin WANG1,2
1 Tsinghua University, China, 2 Chinese Academy of Sciences, China
#Corresponding author: zhaoxinuist@126.com +Presenter

Ice cloud representation and simulation in GCMs has been a challenge with large uncertainties and biases. Different from most conventional microphysics schemes separating ice from snow, we use a single prognostic variable (total ice) to represent the whole spectrum of the ice phase particles. This novel approach is computational efficient and eliminates the intrinsic uncertainties of the empirical threshold used in the ice to snow conversion. The riming impacts on total ice physical properties, such as mass, density and fall speed, are also included via an environmental condition dependent diagnostic riming intensity. The scheme is tested in Community Atmosphere Model, version 5 (CAM5) using 6-year AMIP simulations. Simulation with single-ice scheme showed a reasonable temperature and moisture structure of the atmosphere compared to the ERA-Interim reanalysis data. Compared with the default Morrison-Gettelman scheme, the single-ice scheme improved the LWP and IWP simulations. Relative humidity and zonal wind biases in the default CAM5 is also reduced, especially over the midlatitudes. The remaining issues with the new scheme are the colder tropopause and enhanced total precipitation over the tropics, which will be adjusted via future modifications in the convection scheme.

  AS08-D3-PM2-P-014 (AS08-A006)
 
Water Vapor Changes Under Global Warming and the Linkage to Present-Day Interannual Variabilities in CMIP5 Models
Hui SU#+, Hanii TAKAHASHI, Jonathan JIANG
California Institute of Technology, United States
#Corresponding author: Hui.Su@jpl.nasa.gov +Presenter

The fractional water vapor changes under global warming across 14 Coupled Model Intercomparison Project Phase 5 (CMIP5) simulations are analyzed. We show that the mean fractional water vapor changes under global warming in the tropical upper troposphere between 300 and 100 hPa range from 12.4 %/K to 28.0 %/K across all models while the fractional water vapor changes are about 5−8 %/K in other regions and at lower altitudes. The “upper-tropospheric amplification” of the water vapor change is primarily driven by a larger temperature increase in the upper troposphere than in the lower troposphere per degree of surface warming. The relative contributions of atmospheric temperature and relative humidity changes to the water vapor change in eachmodel vary between 71.5 % to 131.8 % and 24.8% to −20.1 %, respectively. The inter-model differences in the water vapor change is primarily caused by differences in temperature change, except over the inter-tropical convergence zone within 10°S-10ºN where the model differences due to the relative humidity change are significant. Furthermore, we find that there is generally a positive correlation between the rates of water vapor change for long-tem surface warming and those on the interannual time scales. However, the rates of water vapor change under long-term warming have a systematic offset from those on the inter-annual time scales and the dominant contributor to the differences also differs for the two time scales, suggesting caution needs to be taken when inferring long-term water vapor changes from the observed interannual variations.

  AS08-D3-PM2-P-015 (AS08-A009)
 
Modeling of Organic Aerosols Over the South Asian Region in CMIP5 Models
Pawan VATS#+, Dilip GANGULY
Indian Institute of Technology, Delhi, India
#Corresponding author: pawanvats5086@gmail.com +Presenter

In this study we try to understand the various complexities associated with the simulation of organic aerosols (OA) over the South Asian region by analyzing the output of various global models from the coupled model inter-comparison project phase 5 (CMIP5). We also evaluate the performance of various model simulations by comparing the model outputs with available observations from this region. Ten different global chemistry-climate models were considered for the present study. We characterize the contribution of OA towards the total aerosol loading, aerosol optical depth (AOD), concentrations, etc. over the South Asian region simulated from the pre-industrial (PI) to present day (PD) and also for various future Representative Concentration Pathways (RCP) scenarios from the data available for the selected ten different models. Inter-comparison of the simulated OA clearly shows that there is a significant inter-model variability in OA characteristics over the South Asian region. Most CMIP5 models underestimate the simulated AOD and OC concentrations over the South Asia region and especially the Indo-Gangetic plain (IGP) due to both missing emissions of OC as well as due to simplified treatment of SOA (secondary organic aerosol) chemistry in these global models. Some models underestimate the loading of OA significantly with respect to other models as well as available measurements. Performance of a few models is highly unacceptable because they are not only underestimating the OA concentrations but also not able to capture the seasonality in the variations of OA and SOA compare to in-situ measurements. There is a compelling need to improve the emissions of OA and the treatment of SOA chemistry in global climate models in order to improve our understanding about the changing concentrations of these aerosols on the regional climate of South Asia. More results with greater details will be discussed.

  AS08-D3-PM2-P-016 (AS08-A011)
 
CMIP5 Vs CORDEX in the Context of Indian Monsoon
Raju PATHAK#+, Sandeep SAHANY, Saroj Kanta MISHRA, Kartikeya GUPTA, Popat SALUNKE, Abhishek ANAND
Indian Institute of Technology Delhi, India
#Corresponding author: rajuphyamu@gmail.com +Presenter

The Indian summer monsoon is observed to be changing due to the global climate change. Because of its environmental, economic and social impact, it is one of the most anticipated, tracked and studied weather phenomena. The numerical simulations produced by Coupled Model Intercomparison Project Phase 5 (CMIP5) and Coordinated Regional Climate Downscaling Experiment (CORDEX) South Asia Regional Climate Models (RCMs)have beenanalysed under different warming scenario to understand the strength, variability, predictability and associated changes in Indian Summer Monsoon with climate change. This study is particularly aimed to contrast the efficacy of CMIP5 and CORDEX-South Asia RCMs models over Indian region during southwest monsoon. The monsoon simulation with finer resolution (CORDEX) leads to better representation of topographical features including northeastern mountains and Western Ghats than coarser resolution (CMIP5). The study suggeststhe intermodel biases in CMIP5 and CORDEX-South Asia and facilitates precipitation evolution and structure over Indian region with certain degree of uncertainty.

Key words: Indian Summer Monsoon, Climate Change, CMIP5, CORDEX-South Asia

  AS08-D3-PM2-P-018 (AS08-A015)
 
Future Change in Extreme Precipitation Indices by Climate Change
Ga-Young KIM1+, Dong-Hyun CHA1#, Gil LEE1, Chun-Sil JIN1, Dong-Kyou LEE2,3, Myoung-Seok SUH4, Joong-Bae AHN5, Seung-Ki MIN6, Song-You HONG7, Hyun-Suk KANG3
1 Ulsan National Institute of Science and Technology, South Korea, 2 Seoul National University, South Korea, 3 Korea Meteorological Administration, South Korea, 4 Kongju National University, South Korea, 5 Pusan National University, South Korea, 6 Pohang University of Science and Technology, South Korea, 7 Yonsei University, South Korea
#Corresponding author: dhcha@unist.ac.kr +Presenter

Recently frequency and intensity of natural disasters have been increasing due to severe climate change. Because most damages of natural disaster over the Korean Peninsula have been related to extreme precipitation events, it is important to predict future changes of extreme precipitation phenomena caused by climate changes. This study analyzed changes in extreme precipitation indices, which were calculated from detailed climate change scenarios produced by multi regional climate models. 6 core precipitation indices made by STARDEX, which is one of the projects in EU, were chosen. Changes of STARDEX indices of precipitation were analyzed based on the differences between present 25-year (1981-2005) HISTORIDCAL data and future 25-year (2076-2100) RCP 8.5 data by 5 RCMs (HadGEM3-RA, RegCM4, SNURCM, WRF, GRIMs). Gridded precipitation data from RCMs were bilinearly interpolated into 230 cities in South Korea, and the STARDEX indices were calculated for each cities. As a result, 4 of 5 RCMs predicted increasing intensity of precipitation, especially for southern part of South Korea. On the other hands, RCMs predicted increasing maximum consecutive dry day in central region of South Korea. Most of extreme indices changes were related to changes in synoptic conditions (e.g., monsoonal wind, upper-level jet, and subtropical high) and convective instability. It is expected that the results of this study (i.e., future indices changes) can be fruitful references for policy making of disaster management.