World Climate Research Programme Research Articles

КЛІМАТИЧНІ КОМУНІКАЦІЇ МІЖНАРОДНИХ ОРГАНІЗАЦІЙ ТА СУБНАЦІОНАЛЬНИХ СУБ’ЄКТІВ ЯК АКТОРІВВРЕГУЛЮВАННЯ ГЛОБАЛЬНИХ КЛІМАТИЧНИХ ЗМІН

Resolving the issue of global climate change addresses a number of vital issues, including the identification of participants and the scope of their competences and areas of responsibility. One of the most influential actors are international organizations, in particular the UN and its special structures, programs and projects, whose activities are aimed at tackling global climate change, adaptation and mitigation of the effects of climate change. Such specialized entities include the United Nations Environment Program, the World Climate Research Program, the Global Climate Observing System, the Global Ocean Observing System, and the Intergovernmental Panel on Climate Change. It is emphasized that the application of effective communication tools is an important element in the success of these global climate change response structures. It is shown that in the practice of UN specialized agencies such communication tools as evaluation, special and technical reports, summaries, newsletters, methodological guides, video materials are used; annual conferences, thematic seminars, special information events, etc. are held. In major cases, all information is available to the public in the Internet, as well as in print materials. The author explains the importance of subnational actors, such as cities and regions, in reducing emissions and meeting climate targets that successfully implement regional climate initiatives, which later on serve as a platform for demonstrating, testing and disseminating new, cutting-edge climate challenges. The article demonstrates that the information factor in the work of international organizations and subnational actors contributes to the raising awareness among the world community and improving the understanding of the causes and effects of climate change, as well as how countries and communities adapt to the future effects of climate change.

A first-of-its-kind multi-model convection permitting ensemble for investigating convective phenomena over Europe and the Mediterranean

A recently launched project under the auspices of the World Climate Research Program’s (WCRP) Coordinated Regional Downscaling Experiments Flagship Pilot Studies program (CORDEX-FPS) is presented. This initiative aims to build first-of-its-kind ensemble climate experiments of convection permitting models to investigate present and future convective processes and related extremes over Europe and the Mediterranean. In this manuscript the rationale, scientific aims and approaches are presented along with some preliminary results from the testing phase of the project. Three test cases were selected in order to obtain a first look at the ensemble performance. The test cases covered a summertime extreme precipitation event over Austria, a fall Foehn event over the Swiss Alps and an intensively documented fall event along the Mediterranean coast. The test cases were run in both “weather-like” (WL, initialized just before the event in question) and “climate” (CM, initialized 1 month before the event) modes. Ensembles of 18–21 members, representing six different modeling systems with different physics and modelling chain options, was generated for the test cases (27 modeling teams have committed to perform the longer climate simulations). Results indicate that, when run in WL mode, the ensemble captures all three events quite well with ensemble correlation skill scores of 0.67, 0.82 and 0.91. They suggest that the more the event is driven by large-scale conditions, the closer the agreement between the ensemble members. Even in climate mode the large-scale driven events over the Swiss Alps and the Mediterranean coasts are still captured (ensemble correlation skill scores of 0.90 and 0.62, respectively), but the inter-model spread increases as expected. In the case over Mediterranean the effects of local-scale interactions between flow and orography and land–ocean contrasts are readily apparent. However, there is a much larger, though not surprising, increase in the spread for the Austrian event, which was weakly forced by the large-scale flow. Though the ensemble correlation skill score is still quite high (0.80). The preliminary results illustrate both the promise and the challenges that convection permitting modeling faces and make a strong argument for an ensemble-based approach to investigating high impact convective processes.

МІЖНАРОДНО-ПРАВОВЕ ТА ОРГАНІЗАЦІЙНЕ ОФОРМЛЕННЯ АРХІТЕКТУРИ КЛІМАТИЧНИХ ЗМІН

У статті розкрито нормативно-правове забезпечення розв’язання проблем зміни клімату. Проаналізовано зміст основних міжнародно-правових актів, що регулюють питання зміни клімату, та організаційні структури, котрі пов’язані з ними, зокрема кліматичні конференції й Міждержавну групу експертів зі зміни клімату (МГЕЗК). Простежено вплив міжнародних конференцій на прийняття міжнародно-правових документів, які ставили за мету розв’язання глобальної проблеми зміни клімату. Особливу увагу приділено спеціальній резолюції ООН «Збереження глобального клімату для теперішньої та майбутньої діяльності людини», Всесвітній кліматичній програмі, Всесвітній програмі досліджень клімату, Віденській конвенції про охорону озонового шару, Монреальському протоколу про речовини, що руйнують озоновий шар, Базельській конвенції про контроль за трансгра­ничним переміщенням небезпечних відходів та їх видаленням, а також Рамковій Конвенції ООН про зміну клімату, Кіотському протоколу до Рамкової конвенції й Паризькій кліматичній угоді.
 Уважаємо, що потрібно враховувати: кліматична політика здійснюється на різних рівнях – від місцевого до глобального, – а відтак потребує нормативно-правового та організаційного забезпечення розв’язання проблем зміни клімату на всіх цих рівнях, що має перетворюватися на інструментарій прийняття колективних рішень, пошуку компромісів, котрі задовольняють усі сторони переговорів щодо кліматичних змін.

Requirements for a global data infrastructure in support of CMIP6

Abstract. The World Climate Research Programme (WCRP)'s Working Group on Climate Modelling (WGCM) Infrastructure Panel (WIP) was formed in 2014 in response to the explosive growth in size and complexity of Coupled Model Intercomparison Projects (CMIPs) between CMIP3 (2005–2006) and CMIP5 (2011–2012). This article presents the WIP recommendations for the global data infrastructure needed to support CMIP design, future growth, and evolution. Developed in close coordination with those who build and run the existing infrastructure (the Earth System Grid Federation; ESGF), the recommendations are based on several principles beginning with the need to separate requirements, implementation, and operations. Other important principles include the consideration of the diversity of community needs around data – a data ecosystem – the importance of provenance, the need for automation, and the obligation to measure costs and benefits.This paper concentrates on requirements, recognizing the diversity of communities involved (modelers, analysts, software developers, and downstream users). Such requirements include the need for scientific reproducibility and accountability alongside the need to record and track data usage. One key element is to generate a dataset-centric rather than system-centric focus, with an aim to making the infrastructure less prone to systemic failure.With these overarching principles and requirements, the WIP has produced a set of position papers, which are summarized in the latter pages of this document. They provide specifications for managing and delivering model output, including strategies for replication and versioning, licensing, data quality assurance, citation, long-term archiving, and dataset tracking. They also describe a new and more formal approach for specifying what data, and associated metadata, should be saved, which enables future data volumes to be estimated, particularly for well-defined projects such as CMIP6.The paper concludes with a future facing consideration of the global data infrastructure evolution that follows from the blurring of boundaries between climate and weather, and the changing nature of published scientific results in the digital age.

Global sea-level budget 1993–present

Abstract. Global mean sea level is an integral of changes occurring in the climate system in response to unforced climate variability as well as natural and anthropogenic forcing factors. Its temporal evolution allows changes (e.g., acceleration) to be detected in one or more components. Study of the sea-level budget provides constraints on missing or poorly known contributions, such as the unsurveyed deep ocean or the still uncertain land water component. In the context of the World Climate Research Programme Grand Challenge entitled Regional Sea Level and Coastal Impacts, an international effort involving the sea-level community worldwide has been recently initiated with the objective of assessing the various datasets used to estimate components of the sea-level budget during the altimetry era (1993 to present). These datasets are based on the combination of a broad range of space-based and in situ observations, model estimates, and algorithms. Evaluating their quality, quantifying uncertainties and identifying sources of discrepancies between component estimates is extremely useful for various applications in climate research. This effort involves several tens of scientists from about 50 research teams/institutions worldwide (www.wcrp-climate.org/grand-challenges/gc-sea-level, last access: 22 August 2018). The results presented in this paper are a synthesis of the first assessment performed during 2017–2018. We present estimates of the altimetry-based global mean sea level (average rate of 3.1 ± 0.3 mm yr−1 and acceleration of 0.1 mm yr−2 over 1993–present), as well as of the different components of the sea-level budget (http://doi.org/10.17882/54854, last access: 22 August 2018). We further examine closure of the sea-level budget, comparing the observed global mean sea level with the sum of components. Ocean thermal expansion, glaciers, Greenland and Antarctica contribute 42 %, 21 %, 15 % and 8 % to the global mean sea level over the 1993–present period. We also study the sea-level budget over 2005–present, using GRACE-based ocean mass estimates instead of the sum of individual mass components. Our results demonstrate that the global mean sea level can be closed to within 0.3 mm yr−1 (1σ). Substantial uncertainty remains for the land water storage component, as shown when examining individual mass contributions to sea level.

Fidelity of CMIP5-simulated teleconnection between Atlantic multidecadal oscillation and Indian summer monsoon rainfall

The present study aims to provide a relevant ground for attaining deeper perception about the teleconnection between the Atlantic multidecadal oscillation (AMO) and the Indian summer monsoon rainfall (ISMR) in observations as well as in 30 models from the World Climate Research Programme (WCRP) Coupled Model Intercomparison Project Phase 5 (CMIP5). Approximately 73% of models reproduce the internal natural variability allied with AMO, but mostly all underestimate the variance. Amongst these, very few replicate the explicit comma-shaped AMO sea surface temperature (SST) pattern, whereas rest illustrates warm SSTs over the sub-polar region and very weak or non-existent AMO’s signature over the sub-tropical North Atlantic. However, only 53% of models emulate the observed AMO–ISMR relationship. The observational analysis bestows the compelling evidence that the AMO influences ISMR through two physical processes: firstly by modulating the El Nino related anomalous Walker and regional Hadley circulations asymmetrically and secondly through the tropospheric response allied with the Rossby wave train. The models that fail to reproduce the AMO–ISMR teleconnection are incompetent in capturing the first physical mechanism correctly, whereas in general all models show limitations in simulating the second physical mechanism. The results divulge a moderate relationship between the quality of reproducing the AMO pattern and the AMO–ISMR teleconnection in models, particularly with respect to the tropical–extratropical Pacific SST gradients during AMO phases. The models, which do show the observed rainfall response over India, also simulate the large-scale features allied with AMO like the cross-equatorial flow, the tropical easterly jets, the anomalous divergence/convergence over the Indian sub-continent at upper/lower levels, the Webster and Yang Monsoon index, and the Monsoon Hadley Circulation index.

PannEx: The Pannonian Basin Experiment

The almost closed structure of the Pannonian Basin makes it an exceptional natural laboratory for the study of the water and energy cycles, focusing on the physical processes of relevance. The Pannonian Basin Experiment, under the umbrella of the Global Energy and Water Exchanges project of the World Climate Research Programme, aims to achieve a better understanding of the Earth System components and their interactions in the Pannonian Basin. The scientific basis of the PannEx supports research that can better translate and deliver relevant climate data, information and knowledge for societal decision making through the national hydro-meteorological and climate services, research institutes and universities. We outline the framework for the development of the PannEx in the light of international efforts to provide scientific support and involve international research community in integrated approach towards identifying and increasing adaptation capacity in the face of climate change in the Pannonian Basin. As such, PannEx dedicated observational and modeling efforts also strive to reach results with the global impact.

Assessing variations of extreme indices inducing weather-hazards on critical infrastructures over Europe—the INTACT framework

This work has been carried out within the activities of INTACT project, receiving funding from the European Union Seventh Framework Programme (FP7/2007-2013) under grant agreement n° FP7-SEC-2013-1-606799. The information and views set out in this paper are those of the authors and do not necessarily reflect the opinion of the European Union. We acknowledge the World Climate Research Programme's Working Group on Regional Climate, and the Working Group on Coupled Modelling, former coordinating body of CORDEX and responsible panel for CMIP5.

Avoiding Extremes: Benefits of Staying below +1.5 °C Compared to +2.0 °C and +3.0 °C Global Warming

The need to restrict global mean temperature to avoid irreversible climate change is supported by scientific evidence. The need became political practice at the Conference of the Parties in 2015, where the participants decided to limit global warming to not more than +2.0 °C compared to pre-industrial times and to rather aim for a limit of +1.5 °C global warming. Nevertheless, a clear picture of what European climate would look like under +1.5 °C, +2.0 °C and +3.0 °C global warming level (GWL) is still missing. In this study, we will fill this gap by assessing selected climate indices related to temperature and precipitation extremes, based on state of the art regional climate information for Europe taken from the European branch of the World Climate Research Program Coordinated Regional Downscaling Experiment (EURO-CORDEX) ensemble. To assess the impact of these indices under climate change, we investigate the spatial extent of the area of the climate change signal in relation to the affected population. This allows us to demonstrate which climate extremes could be avoided when global warming is kept well below +2.0 °C or even +1.5 °C compared to higher GWLs. The European north–south gradient of tropical nights and hot days is projected to be intensified with an increasing global warming level. For precipitation-related indices, an overall increase in precipitation extremes is simulated, especially under +3.0 °C GWL, for mid- and northern Europe, whereas an increase in dry days is projected for many regions in southern Europe. The benefit of staying below +1.5 °C GWL compared to +2.0 °C GWL is the avoidance of an additional increase in tropical nights and hot days parallel to an increase in dry days in parts of southern Europe as well as an increase in heavy precipitation in parts of Scandinavia. Compared to +3.0 °C GWL, the benefit of staying at +1.5 °C GWL is to avoid a substantial increase (i.e., an increase of more than five dry days and ten tropical nights) in dry days and tropical nights in southern European regions, while, in several European regions and especially in northern Europe, a substantial increase (i.e., more than two heavy precipitation days) in heavy precipitation days could be avoided. This study shows that a statistically significant change in the investigated climate indices can be avoided under +1.5 °C GWL compared to the investigated higher GWLs +2.0 °C and +3.0 °C for the majority of the population in almost all regions. Future studies will investigate compound events where the severity of single extreme events is intensified.

Stochastic Post-Processing of CFSR Daily Precipitation across Canada

ABSTRACTReanalyses, based on numerical weather prediction methods assimilating past observations, provide continuous precipitation datasets and represent interesting options for assessing the climatology of regions with sparse station networks (e.g., northern Canada). However, reanalysis series cannot be used directly because of possible biases and mismatch between their spatial and temporal resolutions with that needed for local applications. To address these issues, a Stochastic Model Output Statistics (SMOS) approach was selected to post-process precipitation series simulated by the Climate Forecast System Reanalysis (CFSR) across Canada. This approach uses CFSR precipitation as a covariate and is based on two regression models: the first one is a logistic regression that deals with precipitation occurrence, and the second is a vector generalized linear model for precipitation intensity. At-site post-processed daily precipitation series are randomly generated using the SMOS approach, and selected climate indicators from the Expert Team on Climate Change Detection and Indices, which is jointly sponsored by the Commission for Climatology of the World Meteorological Organization's (WMO) World Climate Data and Monitoring Programme, the Climate Variability and Predictability Programme of the World Climate Research Programme, and the Joint WMO-IOC Technical Commission for Oceanography and Marine Meteorology (CCI/CLIVAR/JCOMM) are estimated and compared with corresponding observed and CFSR values. The two models in the SMOS approach, in addition to adequately correcting systematic biases, produced better predictions than the climatology of the wet and dry and intensity sequences. Additionally, the SMOS generally yields consistent climate indices when compared with those from CFSR without post-processing, though there is still room for improvement for specific indices (e.g., annual maximum of cumulative wet days).

Designing the Climate Observing System of the Future

AbstractClimate observations are needed to address a large range of important societal issues including sea level rise, droughts, floods, extreme heat events, food security, and freshwater availability in the coming decades. Past, targeted investments in specific climate questions have resulted in tremendous improvements in issues important to human health, security, and infrastructure. However, the current climate observing system was not planned in a comprehensive, focused manner required to adequately address the full range of climate needs. A potential approach to planning the observing system of the future is presented in this article. First, this article proposes that priority be given to the most critical needs as identified within the World Climate Research Program as Grand Challenges. These currently include seven important topics: melting ice and global consequences; clouds, circulation and climate sensitivity; carbon feedbacks in the climate system; understanding and predicting weather and climate extremes; water for the food baskets of the world; regional sea‐level change and coastal impacts; and near‐term climate prediction. For each Grand Challenge, observations are needed for long‐term monitoring, process studies and forecasting capabilities. Second, objective evaluations of proposed observing systems, including satellites, ground‐based and in situ observations as well as potentially new, unidentified observational approaches, can quantify the ability to address these climate priorities. And third, investments in effective climate observations will be economically important as they will offer a magnified return on investment that justifies a far greater development of observations to serve society's needs.

Analysis of rainfall trends over Indo‐Pakistan summer monsoon and related dynamics based on CMIP5 climate model simulations

ABSTRACTUnderstanding the effects of climate change and global warming on the South Asian summer monsoon rainfall trend is critically important for millions of inhabitants of this region. This study investigates seasonal (June–September) rainfall trend over the Indo‐Pakistan subcontinent by using 36 climate model outputs from the World Climate Research Programme's Coupled Model Inter‐comparison Project Phase 5. The historical (1951–2005) and future (2006–2100) simulations under two representative concentration pathways (RCPs), RCP4.5 and RCP8.5, are analysed for this purpose. Model reproducibility is evaluated based on spatial correlation of seasonal rainfall and vertically integrated meridional moisture transport between simulated and observed fields. It is found that the majority of models shows reasonable skill in capturing the observed pattern of rainfall climatology and trend over the subcontinent. Our results showed that the models are more skilful in simulating seasonal mean moisture transport than trend over the Arabian Sea and Bay of Bengal. Of the 36 models analysed, only two models HadGEM2‐AO and CNRM‐CM5 closely approximate both the climatology and trend based on statistical performance metrics. Our results suggest that the strengthening of northwards moisture transport over the Arabian Sea and Bay of Bengal is a likely reason for the increasing rainfall trend over Indo‐Pakistan subcontinent in a warmer climate. The RCP8.5 indicates marked increase in both rainfall and moisture transport trends compared to RCP4.5 forcing scenario.

CMIP5 Diversity in Southern Westerly Jet Projections Related to Historical Sea Ice Area: Strong Link to Strengthening and Weak Link to Shift

Abstract A major feature of projected changes in Southern Hemisphere climate under future scenarios of increased greenhouse gas concentrations is the poleward shift and strengthening of the main eddy-driven belt of midlatitude, near-surface westerly winds (the westerly jet). However, there is large uncertainty in projected twenty-first-century westerly jet changes across different climate models. Here models from the World Climate Research Programme’s phase 5 of the Coupled Model Intercomparison Project (CMIP5) were evaluated to assess linkages between diversity in simulated sea ice area (SIA), Antarctic amplification, and diversity in projected twenty-first-century changes in the westerly jet following the representative concentration pathway 8.5 (RCP8.5) scenario. To help disentangle cause and effect in the coupled model analysis, uncoupled atmosphere-only fixed sea surface experiments from CMIP5 were also evaluated. It is shown that across all seasons, approximately half of the variance in projected RCP8.5 jet strengthening is explained statistically by intermodel differences in simulated historical SIA, whereby CMIP5 models with larger baseline SIA exhibit more ice retreat and less jet strengthening in the future. However, links to jet shift are much weaker and are only statistically significant in austral autumn and winter. It is suggested that a significant cross-model correlation between historical jet strength and projected strength change (r = −0.58) is, at least in part, a result of atmospherically driven historical SIA biases, which then feed back into the atmosphere in future projections. The results emphasize that SIA appears to act in concert with proximal changes in sea surface temperature gradients in relation to model diversity in westerly jet projections.

A Pragmatic Approach to Build a Reduced Regional Climate Projection Ensemble for Germany Using the EURO-CORDEX 8.5 Ensemble

AbstractThe application of an ensemble reduction technique to the European branch of the World Climate Research Program Coordinated Regional Downscaling Experiment (EURO-CORDEX) ensemble at resolution “EUR-11” (~12.5 km) under the RCP8.5 scenario is presented. The technique is based on monthly mean changes between a reference and two future time periods, calculated for eight regions in Germany, of the parameters near-surface air temperature (tas), precipitation totals (pr), contribution of precipitation from very wet days to precipitation totals (R95pTOT), near-surface specific humidity (huss), and surface downwelling shortwave radiation (rsds). The sensitivity of the reduction procedure with respect to a number of tuning parameters is investigated. When the optimal combination of tuning parameters is applied, the technique allows the reduction from 15 to 7 ensemble members, while the reduced ensemble reproduces about 94% of the spread of the full ensemble. Keeping in mind that climate projection ensembles are expected to grow substantially in the near future, this ensemble reduction technique can be useful to limit the computational efforts necessary for further processing and applications such as impact modeling.

Advancing Climate Forecasting

Better forecasts, new products: The World Climate Research Programme coordinates research aimed at improving and extending global climate forecasting capabilities.

Understanding, modeling and predicting weather and climate extremes: Challenges and opportunities

Weather and climate extremes are identified as major areas necessitating further progress in climate research and have thus been selected as one of the World Climate Research Programme (WCRP) Grand Challenges. Here, we provide an overview of current challenges and opportunities for scientific progress and cross-community collaboration on the topic of understanding, modeling and predicting extreme events based on an expert workshop organized as part of the implementation of the WCRP Grand Challenge on Weather and Climate Extremes. In general, the development of an extreme event depends on a favorable initial state, the presence of large-scale drivers, and positive local feedbacks, as well as stochastic processes. We, therefore, elaborate on the scientific challenges related to large-scale drivers and local-to-regional feedback processes leading to extreme events. A better understanding of the drivers and processes will improve the prediction of extremes and will support process-based evaluation of the representation of weather and climate extremes in climate model simulations. Further, we discuss how to address these challenges by focusing on short-duration (less than three days) and long-duration (weeks to months) extreme events, their underlying mechanisms and approaches for their evaluation and prediction.

Systematic Errors in Weather and Climate Models: Nature, Origins, and Ways Forward

The fifth Workshop on Systematic Errors (WSE) in weather and climate models was hosted by Environment and Climate Change Canada (ECCC) on under the auspices of the Working Group on Numerical Experimentation (WGNE), jointly sponsored by the Commission of Atmospheric Sciences of the World Meteorological Organization (WMO) and the World Climate Research Programme (WCRP). This major event welcomed over 200 scientists from the weather and climate communities. The workshop primary goal was to increase the understanding of the nature and cause of systematic errors in numerical models across timescales. Out of 240 abstracts submitted to the workshop, 48 talks and 132 posters were presented.

Evaluating Model Simulations of Twentieth-Century Sea Level Rise. Part I: Global Mean Sea Level Change

Sea level change is one of the major consequences of climate change and is projected to affect coastal communities around the world. Here, global mean sea level (GMSL) change estimated by 12 climate models from phase 5 of the World Climate Research Programme’s Climate Model Intercomparison Project (CMIP5) is compared to observational estimates for the period 1900–2015. Observed and simulated individual contributions to GMSL change (thermal expansion, glacier mass change, ice sheet mass change, landwater storage change) are analyzed and compared to observed GMSL change over the period 1900–2007 using tide gauge reconstructions, and over the period 1993–2015 using satellite altimetry estimates. The model-simulated contributions explain 50% ± 30% (uncertainties 1.65 σ unless indicated otherwise) of the mean observed change from 1901–20 to 1988–2007. Based on attributable biases between observations and models, a number of corrections are proposed, which result in an improved explanation of 75% ± 38% of the observed change. For the satellite era (from 1993–97 to 2011–15) an improved budget closure of 102% ± 33% is found (105% ± 35% when including the proposed bias corrections). Simulated decadal trends increase over the twentieth century, both in the thermal expansion and the combined mass contributions (glaciers, ice sheets, and landwater storage). The mass components explain the majority of sea level rise over the twentieth century, but the thermal expansion has increasingly contributed to sea level rise, starting from 1910 onward and in 2015 accounting for 46% of the total simulated sea level change.

Recent changes in daily climate extremes in a serious water shortage metropolitan region, a case study in Jing-Jin-Ji of China

Extreme climate index is one of the useful tools to monitor and detect climate change. The primary objective of this study is to provide more comprehensively the changes in precipitation and temperature extremes for the period of 1959–2015 in the Jing-Jin-Ji metropolitan region of China, including Beijing city, Tianjin city and Hebei province, which will hopefully provide scientific understanding of the precipitation and temperature-related natural hazards such as flood, drought and heat wave. Daily precipitation and temperature from 26 surface meteorological stations over the study area were used to calculate 14 extreme precipitation indices (EPIs) and 17 extreme temperature indices (ETIs) generated by the joint World Meteorological Organization Commission for Climatology (CCI)/World Climate Research Programme (WCRP) project on Climate Variability and Predictability (CLIVAR) Expect Team on Climate Change Detection, Monitoring and Indices (ETCCDMI). The EPIs and ETIs were generated using the RClimRex software, and the trends were analyzed using the Mann-Kendall non-parametric test and the Thiel-Sen’s slope estimator. The results showed the following: (1) The spatiotemporal variability for daily climate extremes varied for both the EPIs and ETIs between 1959 and 2015. In the case of the EPIs, most of the indices were negative trend-dominated, and for the ETIs, 13 ETIs were positive trend-dominated, and six ETIs were negative trend-dominated. (2) Six types of precipitation intensity EPIs including the R10mm–R250mm were especially defined to detect impacts of climate change on the precipitation events. The results showed that the spatial distributions of increasing trends for these EPIs were similar, mainly located at the south of the Hebei province. (3) In general, the trend magnitudes of fixed-threshold extreme indices were smaller than those of station-related thresholds and non-threshold extreme indices for both the EPIs and ETIs. (4) The spatial distributions of positive and negative trends for both the EPIs and ETIs were scattered. For several indices such as the ID0, SU25, WSDI and TX90p, stations that had statistically significant increasing/decreasing trends at 5% significance level were detected mainly located at the north of the Jing-Jin-Ji metropolitan region. More works on the physical mechanisms behind the varied changes and scattered spatial distributions of trends in the Jing-Jin-Ji metropolitan region are recommended as an extension of this study.

Simulated projection of ISMR over Indian Himalayan region: assessment from CSIRO-CORDEX South Asia experiments

In view of a significant lacuna in the Himalaya-specific knowledge of forthcoming expected changes in the rainfall climatology, this study attempts to assess the expected changes in the Indian summer monsoon rainfall (ISMR) pattern exclusively over the Indian Himalayan Region (IHR) during 2020–2070 in comparison to a baseline period of 1970–2005 under two different warming scenarios, i.e., representative concentration pathways 4.5 and 8.5 (RCP 4.5 and RCP 8.5). Five climate model products from the Commonwealth Scientific and Industrial Research Organization initiated Coordinated Regional Climate Downscaling Experiment of World Climate Research Programme over south Asia region are used for this purpose. Among the several different features of ISMR, this study attempts to investigate expected changes in the average summer monsoon rainfall and percent monthly rainfall to the total monsoon seasonal rainfall using multimodel averages. Furthermore, this study attempts to identify the topographical ranges which are expected to be mostly affected by the changing average monsoon seasonal rainfall over IHR. Results from the multimodel average analysis indicate that the rainfall climatology is expected to increase by >0.75 mm/day over the foothills of northwest Himalaya during 2020–2070, whereas the rainfall climatology is expected to decrease for the flood plains of Brahmaputra under a warmer climate. The monthly percent rainfall of June is expected to rise by more than 1% over the northwestern Himalaya during 2020–2040 (although insignificant at p value 1%) in rainfall climatology during 2020–2070, whereas regions more than 1500 m in eastern Himalaya are expected to experience inconsistent variation in rainfall climatology under a warmer climate scenario.