Dryland expansion in northern China from 1948 to 2008

This study examines the expansion of drylands and regional climate change in northern China by analyzing the variations in aridity index(AI), surface air temperature(SAT), precipitation and potential evapotranspiration(PET) from 1948 to 2008.It is found that the drylands of northern China have expanded remarkably in the last 61 years. The area of drylands of the last 15 years(1994–2008) is 0.65 × 106km2(12%) larger than that in the period 1948–62. The boundary of drylands has extended eastward over Northeast China by about 2° of longitude and by about 1° of latitude to the south along the middleto-lower reaches of the Yellow River. A zonal band of expansion of semi-arid regions has occurred, stretching from western Heilongjiang Province to southern Gansu Province, while shifts to the east of semi-arid regions in dry subhumid regions have also occurred. Results show that the aridity trend of drylands in northern China is highly correlated with the long-term trend of precipitation and PET, and the expansion of semi-arid regions plays a dominant role in the areal extent of drylands, which is nearly 10 times larger than that in arid and subhumid regions.     

全球海气耦合模式对中国区域年代际气候变化预测能力的评估

利用4个海气耦合模式对1960～2005年的多年代际回报结果,评估模式对中国区域年代际气候变化(温度和降水)的预测潜力,并初步给出2005～2015年的气候预测结果。与CMIP3多模式集合1960～2000年结果以及观测实况比较的结果表明:融入观测资料进行同化的年代际气候预测模式,对中国区域温度和降水的模拟能力总体好于CMIP3模式。年代际气候预测模式对温度气候场的模拟仍以"冷偏差"为主,但较之CMIP3模式已有显著改进,中国区域平均的冷偏差减少1.3°C;对降水气候场的模拟仍以"湿偏差"为主,但在华南沿海和西北内陆降水的模拟能力优于CMIP3模式,中国区域平均的湿偏差降低了20%。年代际模式和CMIP3模式都能较好地模拟出中国区域尤其是北方20世纪后期的增暖信号;但CMIP3模式对20世纪后期中国东部降水的旱涝结构演变的模拟与观测相反;而年代际气候预测模式未能再现华北偏旱的变化,但能成功地模拟江淮流域和华南沿海的旱涝演变。2005～2015年的10年预测表明中国区域将继续增暖0.3～0.7°C,且增温幅度北方大于南方,增幅中心位于西北内陆和青藏高原;而降水的变化趋势不显著,黄淮地区、西北内陆和青藏高原的降水略有增加,而西南地区降水将减少。但需要指出的是,这种预测的不确定性是相当大的。     

Projecting South Asian Summer Precipitation in CMIP3 Models:A Comparison of the Simulations with and without Black Carbon

Considering the importance of black carbon(BC), this study began by comparing the 20 th century simulation of South Asian summer climate in IPCC CMIP3, based on the scenario of models with and without BC. Generally, the multi-model mean of the models that include BC reproduced the observed climate relatively better than those that did not. Then, the 21st century South Asian summer precipitation was projected based on the IPCC CMIP3 projection simulations. The projected precipitation in the present approach exhibited a considerable difference from the multimodel ensemble mean(MME) of IPCC AR4 projection simulations, and also from the MME of the models that ignore the effect of BC. In particular, the present projection exhibited a dry anomaly over the central Indian Peninsula,sandwiched between wet conditions on the southern and northern sides of Pakistan and India, rather than homogeneous wet conditions as seen in the MME of IPCC AR4. Thus, the spatial pattern of South Asian summer rainfall in the future may be more complicated than previously thought.     

Projecting South Asian summer precipitation in CMIP3 models: A comparison of the simulations with and without black carbon

Considering the importance of black carbon (BC), this study began by comparing the 20th century simulation of South Asian summer climate in IPCC CMIP3, based on the scenario of models with and without BC. Generally, the multi-model mean of the models that include BC reproduced the observed climate relatively better than those that did not. Then, the 21st century South Asian summer precipitation was projected based on the IPCC CMIP3 projection simulations. The projected precipitation in the present approach exhibited a considerable difference from the multimodel ensemble mean (MME) of IPCC AR4 projection simulations, and also from the MME of the models that ignore the effect of BC. In particular, the present projection exhibited a dry anomaly over the central Indian Peninsula, sandwiched between wet conditions on the southern and northern sides of Pakistan and India, rather than homogeneous wet conditions as seen in the MME of IPCC AR4. Thus, the spatial pattern of South Asian summer rainfall in the future may be more complicated than previously thought.     

CMIP5/AMIP GCM simulations of East Asian summer monsoon

The East Asian summer monsoon （EASM） is a distinctive component of the Asian climate system and critically influences the economy and society of the region.To understand the ability of AGCMs in capturing the major features of EASM,10 models that participated in Coupled Model Intercomparison Project/Atmospheric Model Intercomparison Project （CMIP5/AMIP）,which used observational SST and sea ice to drive AGCMs during the period 1979-2008,were evaluated by comparing with observations and AMIP Ⅱ simulations.The results indicated that the multi-model ensemble （MME） of CMIP5/AMIP captures the main characteristics of precipitation and monsoon circulation,and shows the best skill in EASM simulation,better than the AMIP Ⅱ MME.As for the Meiyu/Changma/Baiyu rainbelt,the intensity of rainfall is underestimated in all the models.The biases are caused by a weak western Pacific subtropical high （WPSH） and accompanying eastward southwesterly winds in group Ⅰ models,and by a too strong and west-extended WPSH as well as westerly winds in group Ⅱ models.Considerable systematic errors exist in the simulated seasonal migration of rainfall,and the notable northward jumps and rainfall persistence remain a challenge for all the models.However,the CMIP5/AMIP MME is skillful in simulating the western North Pacific monsoon index （WNPMI）.     

CMIP6模式对中国东部地区水循环的模拟能力评估

本文基于观测和再分析资料,采用Brubaker二元模型评估了第六次国际耦合模式比较计划（CMIP6）中19个模式对中国东部季风区气候态水循环过程的模拟能力,并分析了模拟误差来源。结果表明,CMIP6模式集合平均（MME）能够合理再现观测降水和蒸发的年平均气候态空间分布及年循环特征,与观测值的空间相关系数分别为0.92和0.87。较之观测,MME高估了华北地区降水（0.55 mm d?1）,低估了华南沿海地区降水（?0.3 mm d?1）。所有CMIP6模式均高估蒸发强度（偏差0.03～0.98 mm d?1）,使得模拟的降水与蒸发之差偏少。模式整体能够模拟出我国东部季风区降水再循环率及不同边界水汽来源的贡献率,但低估了由南边界进入季风区的水汽贡献,导致东亚季风区偏干。通过分析模式对影响水汽通量的两个气象要素（风速和大气比湿）的模拟能力,发现研究区南边界的风速大小决定了模式间水汽输送差异。南边界风速越大的模式,由南边界进入的水汽通量越大,模式模拟的降水越多。西北太平洋辐合带的东西位置是影响南边界南风速的重要系统之一,辐合带位置偏东的模式模拟的南风强度较弱,使得水汽输送偏弱、降水偏少;反之,南边界水汽输送偏强、降水偏多。本文通过评估最新一代CMIP6模式在东亚水循环方面的模拟性能,指出了当前气候模式在模拟西太平洋辐合带位置方面存在的偏差及其对东亚水循环的影响。     

Projected change in East Asian summer monsoon precipitation under RCP scenario

Future changes in East Asian summer monsoon precipitation climatology, frequency, and intensity are analyzed using historical climate simulations and future climate simulations under the RCP4.5 scenario using the World Climate Research Programme’s (WCRP) Coupled Model Intercomparison Project 5 (CMIP5) multi-model dataset. The model reproducibility is evaluated, and well performance in the present-day climate simulation can be obtained by most of the studied models. However, underestimation is obvious over the East Asian region for precipitation climatology and precipitation intensity, and overestimation is observed for precipitation frequency. The overestimation of precipitation frequency is mainly due to the large positive bias of the light precipitation (precipitation <10 mm/day) days, and the underestimation of precipitation intensity is mainly caused by the negative bias of the intense precipitation (precipitation >10 mm/day) intensity. For the future climate simulations, simple multi-model ensemble (MME) averages using all of the models show increases in precipitation and its intensity over almost all of East Asia, while the precipitation frequency is projected to decrease over eastern China and around Japan and increase in other regions. When the weighted MME is considered, no large difference can be observed compared with the simple MME. For the MME using the six best models that have good performance in simulating the present-day climate, the future climate changes over East Asia are very similar to those predicted using all of the models. Further analysis shows that the frequency and intensity of intense precipitation events are also projected to significantly increase over East Asia. Increases in precipitation frequency and intensity are the main contributors to increases in precipitation, and the contribution of frequency increases (contributed by 40.8 % in the near future and by 58.9 % by the end of the twenty-first century) is much larger than that of intensity increases (contributed by 29.9 % in the near future and by 30.1 % by the end of the twenty-first century). This finding also implies an increased risk of intense precipitation events over the East Asian region under global warming scenario. These results regarding future climate simulations show much greater reliability than those using CMIP3 simulations.     

CMIP6全球气候模式对中国极端降水模拟能力的评估及其与CMIP5的比较

对CMIP6全球气候模式在中国地区极端降水的模拟能力进行了综合评估.基于CN05.1观测数据集和32个CMIP6全球气候模式的降水数据,采用8个常用极端降水指数对极端降水进行了定量描述.研究结果表明,在极端降水的气候平均态方面,CMIP6多模式集合对1961—2005年中国地区区域平均的8个极端降水指数模拟的平均相对误...     

CMIP5模式对中国东北气候模拟能力的评估

利用CN05观测资料和参与IPCC第五次评估报告的45个全球气候系统模式的模拟结果,分析了新一代全球气候模式对中国东北三省(1961~2005年)气温和降水的模拟能力。结果表明:1)绝大多数模式都能较好地模拟出研究区内显著增温的趋势,对气温的年际变化模拟能力则相对有限;2)所有模式均能很好地再现气温气候态的空间分布特征,且多模式集合模拟结果优于绝大多数单个模式,空间相关系数达到了0.96;3)对于降水的模拟结果,模式间差异较大,多模式集合能较好地再现其空间分布规律(空间相关系数为0.86),对降水年际变化及线性变化趋势的模拟能力则较差。总体来说,多模式集合对东北气候的时空变化特征具有一定的模拟能力,且对气温模拟效果优于降水,对空间分布的模拟能力优于时间变化。     

Does CMIP6 Inspire More Confidence in Simulating Climate Extremes over China?

Based on climate extreme indices calculated from a high-resolution daily observational dataset in China during1961–2005, the performance of 12 climate models from phase 6 of the Coupled Model Intercomparison Project(CMIP6),and 30 models from phase 5 of CMIP(CMIP5), are assessed in terms of spatial distribution and interannual variability. The CMIP6 multi-model ensemble mean(CMIP6-MME) can simulate well the spatial pattern of annual mean temperature,maximum daily maximum temperature, and minimum daily minimum temperature. However, CMIP6-MME has difficulties in reproducing cold nights and warm days, and has large cold biases over the Tibetan Plateau. Its performance in simulating extreme precipitation indices is generally lower than in simulating temperature indices. Compared to CMIP5, CMIP6 models show improvements in the simulation of climate indices over China. This is particularly true for precipitation indices for both the climatological pattern and the interannual variation, except for the consecutive dry days. The arealmean bias for total precipitation has been reduced from 127%(CMIP5-MME) to 79%(CMIP6-MME). The most striking feature is that the dry biases in southern China, very persistent and general in CMIP5-MME, are largely reduced in CMIP6-MME. Stronger ascent together with more abundant moisture can explain this reduction in dry biases. Wet biases for total precipitation, heavy precipitation, and precipitation intensity in the eastern Tibetan Plateau are still present in CMIP6-MME, but smaller, compared to CMIP5-MME.     

Evaluation of the performance of CMIP5 and CMIP6 models in simulating the South Pacific Quadrupole-ENSO relationship

先前的观测研究表明,南太平洋四极子海温模态(SPQ)可以有效地作为ENSO的前兆信号.本文利用20个CMIP6模式及其对应的20个先前的CMIP5模式的工业化前气候模拟试验数据,评估和比较了CMIP6以及CMIP5模式对SPQ与ENSO的关系的模拟能力.结果表明,大多数CMIP5和CMIP6模式可以合理地模拟SPQ的基...     

中国干湿区变化与预估

本文采用干湿指数对1962~2011年中国干湿区范围变化进行了集中分析,并利用CMIP5（Coupled Model Intercomparison Project Phase 5）模式对其变化趋势开展了预估研究。结果表明,1962~2011年平均极端干旱区、干旱区、半干旱区、半湿润区和湿润区分别占中国陆地总面积的2.8%、11.7%、22.4%、32.6%和30.5%。期间,中国区域年干湿指数总体上呈现下降趋势,空间上表现为西部湿润化和东部干旱化的特征。显著缩小的是湿润区和极端干旱区,半湿润区、半干旱区和干旱区则显著扩大,这表明中国气候敏感区域在扩张。春季和秋季干湿指数变化趋势的空间分布与年平均的较为一致,冬季西北呈干旱化,夏季东南部地区为湿润化。相对于参考时段1986~2005年,在RCP4.5（Representative Concentration Pathway 4.5）情景下18个气候模式中位数的预估结果中,降水仅在东南南部减少,而潜在蒸散发在全区域增加,由于潜在蒸散发的增量超过了降水的增幅,中国区域将整体趋于干旱化,仅在西北地区呈湿润化特征;未来湿润区、干旱区和极端干旱区缩小,气候敏感性高的半湿润区和半干旱区仍将扩大。     

How Frequently Will the Persistent Heavy Rainfall over the Middle and Lower Yangtze River Basin in Summer 2020 Happen under Global Warming?

The middle and lower Yangtze River basin (MLYRB) suffered persistent heavy rainfall in summer 2020, with nearly continuous rainfall for about six consecutive weeks. How the likelihood of persistent heavy rainfall resembling that which occurred over the MLYRB in summer 2020 (hereafter 2020PHR-like event) would change under global warming is investigated. An index that reflects maximum accumulated precipitation during a consecutive five-week period in summer (Rx35day) is introduced. This accumulated precipitation index in summer 2020 is 60% stronger than the climatology, and a statistical analysis further shows that the 2020 event is a 1-in-70-year event. The model projection results derived from the 50-member ensemble of CanESM2 and the multimodel ensemble (MME) of the CMIP5 and CMIP6 models show that the occurrence probability of the 2020PHR-like event will dramatically increase under global warming. Based on the Kolmogorov–Smirnoff test, one-third of the CMIP5 and CMIP6 models that have reasonable performance in reproducing the 2020PHR-like event in their historical simulations are selected for the future projection study. The CMIP5 and CMIP6 MME results show that the occurrence probability of the 2020PHR-like event under the present-day climate will be double under lower-emission scenarios (CMIP5 RCP4.5, CMIP6 SSP1-2.6, and SSP2-4.5) and 3–5 times greater under higher-emission scenarios (3.0 times for CMIP5 RCP8.5, 2.9 times for CMIP6 SSP3-7.0, and 4.8 times for CMIP6 SSP5-8.5). The inter-model spread of the probability change is small, lending confidence to the projection results. The results provide a scientific reference for mitigation of and adaptation to future climate change.     

High-resolution simulations for Vietnam - methodology and evaluation of current climate

To assist the government of Vietnam in its efforts to better understand the impacts of climate change and prioritise its adaptation measures, dynamically downscaled climate change projections were produced across Vietnam. Two Regional Climate Models (RCMs) were used: CSIRO’s variable-resolution Conformal-Cubic Atmospheric Model (CCAM) and the limited-area model Regional Climate Model system version 4.2 (RegCM4.2). First, global CCAM simulations were completed using bias- and variance-corrected sea surface temperatures as well as sea ice concentrations from six Coupled Model Intercomparison Project Phase 5 (CMIP5) global climate models. This approach is different from other downscaling approaches as it does not use any atmospheric fields from the GCMs. The global CCAM simulations were then further downscaled to 10 km using CCAM and to 20 km using RegCM4.2. Evaluations of temperature and precipitation for the current climate (1980-2000) were completed using station data as well as various gridded observational datasets. The RCMs were able to reproduce reasonably well most of the important characteristics of observed spatial patterns and annual cycles of temperature. Average and minimum temperatures were well simulated (biases generally less than 1oC), while maximum temperatures had biases of around 1oC. For precipitation, although the RCMs captured the annual cycle, RegCM4.2 was too dry in Oct.-Nov. (-60% bias), while CCAM was too wet in Dec.- Mar. (130% bias). Both models were too dry in summer and too wet in winter (especially in northern Vietnam). The ability of the ensemble simulations to capture current climate increases confidence in the simulations of future climate.     

Temperature and precipitation in the context of the annual cycle over Asia: Model evaluation and future change

Since the early or late arrival of monsoon rainfall can be devastating to agriculture and economy, the prediction of the onset of monsoon is a very important issue. The Asian monsoon is characterized by a strong annual cycle with rainy summer and dry winter. Nevertheless, most of monsoon studies have focused on the seasonal-mean of temperature and precipitation. The present study aims to evaluate a total of 27 coupled models that participated in phase 5 of the Coupled Model Intercomparison Project (CMIP5) for projection of the time evolution and the intensity of Asian monsoon on the basis of the annual cycle of temperature and precipitation. And future changes of onset, retreat, and intensity of monsoon are analyzed. Four models for good seasonal-mean (GSM) and good harmonic (GH) groups, respectively, are selected. GSM is based on the seasonal-mean of temperature and precipitation in summer and winter, and GH is based on the annual cycle of temperature and precipitation which represents a characteristic of the monsoon. To compare how well the time evolution of the monsoon is simulated in each group, the onset, retreat, and duration of Asian monsoon are examined. The highest pattern correlation coefficient (PCC) of onset, retreat, and duration between the reanalysis data and model outputs demonstrates that GH models’ MME predicts time evolution of monsoon most precisely, with PCC values of 0.80, 0.52, and 0.63, respectively. To predict future changes of the monsoon, the representative concentration pathway 4.5 (RCP 4.5) experiments for the period of 2073-2099 are compared with historical simulations for the period of 1979-2005 from CMIP5 using GH models’ MME. The Asian monsoon domain is expanded by 22.6% in the future projection. The onset date in the future is advanced over most parts of Asian monsoon region. The duration of summer Asian monsoon in the future projection will be lengthened by up to 2 pentads over the Asian monsoon region, as a result of advanced onset. The Asian monsoon intensity becomes stronger with the passage of time. This study has important implication for assessment of CMIP5 models in terms of the prediction of time evolution and intensity of Asian monsoon based on the annual cycle of temperature and precipitation.     

The South Pacific Convergence Zone in CMIP5 simulations of historical and future climate

The South Pacific Convergence Zone (SPCZ) is evaluated in historical simulations from 26 Coupled Model Intercomparison Project Phase 5 (CMIP5) models, and compared with previous generation CMIP3 models. A subset of 24 CMIP5 models are able to simulate a distinct SPCZ in the December to February (DJF) austral summer, although the position of the SPCZ in these models is too zonal compared with observations. The spatial pattern of SPCZ precipitation is improved in CMIP5 models relative to CMIP3 models, although the spurious double ITCZ precipitation band in the eastern Pacific is intensified in many CMIP5 models. All CMIP5 models examined capture some interannual variability of SPCZ latitude, and 19 models simulate a realistic correlation with El Niño–Southern Oscillation. In simulations of the twenty-first century under the RCP8.5 emission scenario, no consistent shift in the mean position of the DJF SPCZ is identified. Several models simulate significant shifts northward, and a similar number of models simulate significant southward shifts. The majority of CMIP5 models simulate an increase in mean DJF SPCZ precipitation, and there is an intensification of the eastern Pacific double ITCZ precipitation band in many models. Most models simulate regions of increased precipitation in the western part of the SPCZ and near the equator, and regions of decreased precipitation at the eastern edge of the SPCZ. Decomposition of SPCZ precipitation changes into dynamic and thermodynamic components reveals predominantly increased precipitation due to thermodynamic changes, while dynamic changes lead to regions of both positive and negative precipitation anomalies.     

CMIP6模式对亚洲陆地生态系统的模拟评估与预估

基于国际耦合模式比较计划第六阶段（CMIP6）模式模拟以及观测数据,评估了9个CMIP6模式对亚洲地区叶面积指数（LAI)、总初级生产力（GPP）和净初级生产力（NPP）的模拟性能。模拟评估结果表明,9个CMIP6模式能够较好地模拟出亚洲地区陆地生态系统LAI、GPP和NPP的时空分布特征。综合来看,多模式集合（MME）模拟效果最佳,其模拟的LAI、GPP和NPP与观测的空间相关系数分别达到0.90、0.81和0.89,均方根误差在0.5左右。在此基础上,利用MME结果进一步预估了亚洲地区陆地生态系统在SSP1-2.6、SSP2-4.5和SSP5-8.5情景下的未来变化。总体而言,亚洲地区LAI、GPP和NPP到21世纪末都呈现上升趋势。其中,温室气体高排放情景下的上升趋势大于温室气体低排放情景下的上升趋势,亚洲中高纬度地区的增幅大于低纬度地区的增幅。从区域平均来看,到21世纪末期,与当今气候态相比,北亚LAI、GPP和NPP的增幅最大,其在SSP5-8.5情景下分别增加68%、106%和90%;东南亚增幅最小,分别为15%、34%和39%。在SSP1-2.6情景下,北亚LAI、GPP和NPP在21世纪末的增幅分别为23%、29%和26%;东南亚分别为3%、10%和11%,意味着未来全球变暖背景下亚洲区域陆地生态系统变绿和固碳幅度加强。     

CMIP5 simulated change in the intensity of the Hadley and Walker circulations from the perspective of velocity potential

Based on the simulations of 31 global models in CMIP5, the performance of the models in simulating the Hadley and Walker circulations is evaluated. In addition, their change in intensity by the end of the 21 st century(2080–2099) under the RCP4.5 and RCP8.5 scenarios, relative to 1986–2005, is analyzed from the perspective of 200 h Pa velocity potential.Validation shows good performance of the individual CMIP5 models and the multi-model ensemble mean(MME) in reproducing the meridional(zonal) structure and magnitude of Hadley(Walker) circulation. The MME can also capture the observed strengthening tendency of the winter Hadley circulation and weakening tendency of the Walker circulation. Such secular trends can be simulated by 39% and 74% of the models, respectively. The MME projection indicates that the winter Hadley circulation and the Walker circulation will weaken under both scenarios by the end of the 21 st century. The weakening amplitude is larger under RCP8.5 than RCP4.5, due to stronger external forcing. The majority of the CMIP5 models show the same projection as the MME. However, for the summer Hadley circulation, the MME shows little change under RCP4.5 and large intermodel spread is apparent. Around half of the models project an increase, and the other half project a decrease. Under the RCP8.5 scenario, the MME and 65% of the models project a weakening of the summer southern Hadley circulation.     

CMIP5全球气候模式对中国地区降水模拟能力的评估

使用多种观测资料和43个参加耦合模式比较计划第五阶段（CMIP5）的全球气候模式模拟数据,评估分析了全球气候模式对中国地区1980-2005年降水特征的模拟能力。结果表明：多数CMIP5模式能够模拟出中国降水由西北向东南递增的分布特点,这与耦合模式比较计划第三阶段（CMIP3）的模式模拟结果类似,但华南地区降水模拟偏少,西部高原地区降水模拟偏多。模式能够较好地模拟出降水冬弱夏强的季节变化特征,但降水模拟系统性偏多。从EOF分析结果来看,多数CMIP5模式可以再现中国地区年平均降水的时空变化特征,集合平均的表现优于CMIP3。多模式集合在月、季、年时间尺度下模拟的平均值优于大部分单个模式的结果。CMIP5中6个中国模式的模拟能力与其他模式相当,其中FGOALS-g2、BCC-CSM1-1-m的模拟能力相对较好。     

The first multi-model ensemble of regional climate simulations at kilometer-scale resolution part 2: historical and future simulations of precipitation

This paper presents the first multi-model ensemble of 10-year, “convection-permitting” kilometer-scale regional climate model (RCM) scenario simulations downscaled from selected CMIP5 GCM projections for historical and end of century time slices. The technique is to first downscale the CMIP5 GCM projections to an intermediate 12–15 km resolution grid using RCMs, and then use these fields to downscale further to the kilometer scale. The aim of the paper is to provide an overview of the representation of the precipitation characteristics and their projected changes over the greater Alpine domain within a Coordinated Regional Climate Downscaling Experiment Flagship Pilot Study and the European Climate Prediction system project, tasked with investigating convective processes at the kilometer scale. An ensemble of 12 simulations performed by different research groups around Europe is analyzed. The simulations are evaluated through comparison with high resolution observations while the complementary ensemble of 12 km resolution driving models is used as a benchmark to evaluate the added value of the convection-permitting ensemble. The results show that the kilometer-scale ensemble is able to improve the representation of fine scale details of mean daily, wet-day/hour frequency, wet-day/hour intensity and heavy precipitation on a seasonal scale, reducing uncertainty over some regions. It also improves the representation of the summer diurnal cycle, showing more realistic onset and peak of convection. The kilometer-scale ensemble refines and enhances the projected patterns of change from the coarser resolution simulations and even modifies the sign of the precipitation intensity change and heavy precipitation over some regions. The convection permitting simulations also show larger changes for all indices over the diurnal cycle, also suggesting a change in the duration of convection over some regions. A larger positive change of frequency of heavy to severe precipitation is found. The results are encouraging towards the use of convection-permitting model ensembles to produce robust assessments of the local impacts of future climate change.