Advanced risk-based event attribution for heavy regional rainfall events

Abstract Risk-based event attribution (EA) science involves probabilistically estimating alterations of the likelihoods of particular weather events, such as heat waves and heavy rainfall, owing to global warming, and has been considered as an effective approach with regard to climate change adaptation. However, risk-based EA for heavy rain events remains challenging because, unlike extreme temperature events, which often have a scale of thousands of kilometres, heavy rainfall occurrences depend on mesoscale rainfall systems and regional geographies that cannot be resolved using general circulation models (GCMs) that are currently employed for risk-based EA. Herein, we use GCM large-ensemble simulations and high-resolution downscaled products with a 20-km non-hydrostatic regional climate model (RCM), whose boundary conditions are obtained from all available GCM ensemble simulations, to show that anthropogenic warming increased the risk of two record-breaking regional heavy rainfall events in 2017 and 2018 over western Japan. The events are examined from the perspective of rainfall statistics simulated by the RCM and from the perspective of background large-scale circulation fields simulated by the GCM. In the 2017 case, precipitous terrain and a static pressure pattern in the synoptic field helped reduce uncertainty in the dynamical components, whereas in the 2018 case, a static pressure pattern in the synoptic field provided favourable conditions for event occurrence through a moisture increase under warmer climate. These findings show that successful risk-based EA for regional extreme rainfall relies on the degree to which uncertainty induced by the dynamic components is reduced by background conditioning.

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Approaches to attribution of extreme temperature and precipitation events using multi-model and single-member ensembles of general circulation models

Advances in Statistical Climatology Meteorology and Oceanography ◽

10.5194/ascmo-5-133-2019 ◽

2019 ◽

Vol 5 (2) ◽

pp. 133-146 ◽

Cited By ~ 1

Author(s):

Sophie C. Lewis ◽

Sarah E. Perkins-Kirkpatrick ◽

Andrew D. King

Keyword(s):

General Circulation ◽

Climate Model ◽

Extreme Event ◽

Extreme Temperature ◽

General Circulation Models ◽

Cmip5 Models ◽

Spatial And Temporal Scales ◽

Temperature And Precipitation ◽

Event Attribution ◽

Precipitation Events

Abstract. Extreme temperature and precipitation events occurring in Australia in recent decades have caused significant socio-economic and environmental impacts, and thus determining the factors contributing to these extremes is an active area of research. Many recently occurring record-breaking temperature and rainfall events have now been examined from an extreme event attribution (EEA) perspective. This paper describes a set of studies that have examined the causes of extreme climate events using various general circulation models (GCMs), presenting a comprehensive methodology for GCM-based attribution of extremes of temperature and precipitation observed on large spatial and temporal scales in Australia. First, we review how Coupled Model Intercomparison Project Phase 5 (CMIP5) models have been used to examine the changing odds of observed extremes. Second, we review how a large perturbed initial condition ensemble of a single climate model (CESM) has been used to quantitatively examine the changing characteristics of Australian heat extremes. For each approach, methodological details and applications are provided and limitations highlighted. The conclusions of this methodological review discuss the limitations and uncertainties associated with this approach and identify key unexplored applications of GCM-based attribution of extremes. Ideally, this information will be useful for the application of the described extreme event attribution approaches elsewhere.

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Assessing the response of groundwater quantity and travel time distribution to 1.5, 2 and 3 degrees global warming in a mesoscale central German basin

10.5194/hess-2019-9 ◽

2019 ◽

Author(s):

Miao Jing ◽

Rohini Kumar ◽

Falk Heße ◽

Stephan Thober ◽

Oldrich Rakovec ◽

...

Keyword(s):

Global Warming ◽

Travel Time ◽

General Circulation ◽

General Circulation Models ◽

Hydrologic Model ◽

Groundwater Model ◽

Groundwater System ◽

Ensemble Simulations ◽

Regional Groundwater ◽

German Basin

Abstract. Groundwater is the biggest single source of high-quality fresh water worldwide, which is also continuously threatened by the changing climate. This paper is designed to investigate the response of regional groundwater system to the climate change under three global warming levels (1.5, 2, and 3 °C) in a central German basin (Nägelstedt). This investigation is conducted by deploying an integrated modeling workflow that consists of a mesoscale Hydrologic Model (mHM) and a fully-distributed groundwater model OpenGeoSys (OGS). mHM is forced by five general circulation models under three representative concentration pathways. The diffuse recharges estimated by mHM are used as outer forcings of the OGS groundwater model to compute changes in groundwater levels and travel time distributions. Simulation results indicate that under future climate scenarios, groundwater recharges and levels are expected to increase slightly. Meanwhile, the mean travel time is expected to decrease compared to the historical average. However, the ensemble simulations do not all agree on the sign of relative change. The ensemble simulations do not show a systematic relationship between the predicted change and the warming level, but they indicate an increased variability in predicted changes with the enhanced warming level from 1.5 to 3 °C. This study indicates that a higher warming level may introduce more uncertain and extreme events for the studied regional groundwater system.

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Assessment of future heat events for the city of Augsburg by means of a normal vector based analog approach

10.5194/egusphere-egu2020-3438 ◽

2020 ◽

Author(s):

Christian Merkenschlager ◽

Christoph Beck ◽

Elke Hertig

Keyword(s):

Time Series ◽

Urban Areas ◽

General Circulation ◽

Heat Waves ◽

Selection Process ◽

General Circulation Models ◽

Normal Vector ◽

Urban Structure ◽

Data Set ◽

The City

Under enhanced anthropogenic greenhouse gas forcing heat waves are only one example of climatic risks mankind has to deal with. Especially in urban areas where most of the people will live until the end of the 21st century heat waves are a serious risk factor since the urban heat island will reinforce such events. For the city of Augsburg, new analog methods are utilized for assessing the development and impacts of heat waves taking into account the varying urban structure.For model calibration the temperature data from the Augsburg-M&#252;hlhausen weather station operated by the German Weather Service (DWD) and atmospheric circulation variables of the ERA5 reanalysis data set were used to analyze the recent temperature development. For this purpose, the least deviation of the normal vector was used to determine a subsample of analogs corresponding to the day of interest. The normal vector was derived from the regression plane of the prevailing circulation on the respective day. Subsequently, the temperature patterns were used to define the analog day from the subsample. For future periods, the same method was applied to model data for two representative concentration pathways (RCP4.5, RCP8.5) of different general circulation models (GCM: ACCESS1-0, CNRM-CM5, MPI-ESM-LR). Thus, we derive future time series of analogs corresponding to events prevailing in the observational period. To account for projected trends of the GCMs, the trends of all time-series were first removed and, after the analog selection process, added again according to the trends of the GCMs.Temperature extremes are defined as days with temperatures exceeding the 90th quantile (Q90) and heat days are defined as days where at least two temperature indices (TMIN, TMEAN, TMAX) exceed Q90. When at least three consecutive days are defined as heat day a heat wave is proclaimed. Analysis have shown that under consideration of RCP8.5 (RCP4.5) and all model runs the number of heat days in the end of the 21st century will be nine (five) times higher than within the reference period 1970-2000. Furthermore, the mean duration of heatwaves will extend by factor four (two), whereby heat waves of more than 30 (15) consecutive days are possible.

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Projection of Future Heat Waves in the United States. Part I: Selecting a Climate Model Subset

Atmosphere ◽

10.3390/atmos11060587 ◽

2020 ◽

Vol 11 (6) ◽

pp. 587

Author(s):

Javad Shafiei Shiva ◽

David G. Chandler

Keyword(s):

United States ◽

General Circulation ◽

Climate Model ◽

Heat Waves ◽

Well Being ◽

General Circulation Models ◽

The United States ◽

Wide Range ◽

Overall Performance ◽

Impact Predictions

The widespread increase in global temperature is driving more frequent and more severe local heatwaves within the contiguous United States (CONUS). General circulation models (GCMs) show increasing, but spatially uneven trends in heatwave properties. However, the wide range of model outputs raises the question of the suitability of this method for indicating the future impacts of heatwaves on human health and well-being. This work examines the fitness of 32 models from CMIP5 and their ensemble median to predict a set of heatwave descriptors across the CONUS, by analyzing their capabilities in the simulation of historical heatwaves during 1950–2005. Then, we use a multi-criteria decision-making tool and rank the overall performance of each model for 10 locations with different climates. We found GCMs have different capabilities in the simulation of historical heatwave characteristics. In addition, we observed similar performances for GCMs over the areas with a partially similar climate. The ensemble model showed better performance in simulation of historical heatwave intensity in some locations, while other individual GCMs represented heatwave time-related components more similar to observations. These results are a step towards the use of contemporary weather models to guide heatwave impact predictions.

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Volcanic hazard exacerbated by future global warming–driven increase in heavy rainfall.

10.31223/x5z906 ◽

2021 ◽

Author(s):

Jamie Farquharson ◽

Falk Amelung

Keyword(s):

Global Warming ◽

General Circulation ◽

Heavy Rainfall ◽

Spatial Scales ◽

General Circulation Models ◽

Volcanic Hazards ◽

Volcanic Arcs ◽

Increased Risk ◽

Future Global Warming ◽

Wide Range

Heavy rainfall drives a range of eruptive and noneruptive volcanic hazards; over the Holocene, the incidence of many such hazards has increased due to rapid climate change. Here we show that extreme heavy rainfall is projected to increase with continued global warming throughout the 21st century in most subaerial volcanic regions, dramatically increasing the potential for rainfall-induced volcanic hazards. This result is based on a comparative analysis of nine general circulation models, and is prevalent across a wide range of spatial scales, from countries and volcanic arcs down to individual volcanic systems. Our results suggest that if global warming continues unchecked, the incidence of primary and secondary rainfall-related volcanic activity—such as dome explosions or flank collapse—will increase at more than 700 volcanoes around the globe. Improved coupling between scientific observations—in particular, of local and regional precipitation—and policy decisions, may go some way towards mitigating the increased risk throughout the next 80 years.

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Evaluation of the CMIP5 general circulation models for simulating the precipitation and temperature of the Koshi River Basin in Nepal

Journal of Water and Climate Change ◽

10.2166/wcc.2021.124 ◽

2021 ◽

Author(s):

Pragya Pradhan ◽

Sangam Shrestha ◽

S. Mohana Sundaram ◽

Salvatore G. P. Virdis

Keyword(s):

River Basin ◽

General Circulation ◽

Performance Indicator ◽

Extreme Temperature ◽

General Circulation Models ◽

Climate Impact ◽

Climate Indices ◽

Extreme Precipitation Events ◽

Koshi River Basin ◽

Precipitation And Temperature

Abstract This study evaluates the performance of 12 different general circulation models (GCMs) from the Coupled Model Intercomparison Project Phase 5 (CMIP5) to simulate precipitation and temperature in the Koshi River Basin, Nepal. Four statistical performance indicators: correlation coefficient, normalised root-mean-square deviation (NMRSD), absolute NMRSD, and average absolute relative deviation are considered to evaluate the GCMs using historical observations. Seven different climate indices: consecutive dry days, consecutive wet days, cold spell duration index, warm spell duration index, frost days, very wet days, and simple daily intensity index are considered to identify the most suitable models for the basin and future climate impact assessment studies. Weights for each performance indicator are determined using the entropy method, with compromise programming applied to rank the GCMs based on the Euclidian distant technique. The results suggest that CanESM2 and CSIRO-MK3.6.0 are the most suitable for predicting extreme precipitation events, and BCC-CSM 1.1, CanESM2, NorESM1-M, and CNRM-CM5 for extreme temperature events in Himalayan river basins. Overall, IPSL-CM5A-MR, CanESM2, CNRM-CM5, BCC-CSM 1.1, NorESM1-M, and CSIRO-Mk3.6.0 are deemed suitable models for predicting precipitation and temperature in the Koshi River Basin, Nepal.

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Regional Climate Model Projections and Uncertainties of U.S. Summer Heat Waves

Journal of Climate ◽

10.1175/2010jcli3349.1 ◽

2010 ◽

Vol 23 (16) ◽

pp. 4447-4458 ◽

Cited By ~ 45

Author(s):

Kenneth E. Kunkel ◽

Xin-Zhong Liang ◽

Jinhong Zhu

Keyword(s):

United States ◽

Regional Climate Model ◽

Heat Wave ◽

General Circulation ◽

Climate Model ◽

Heat Waves ◽

Regional Climate ◽

General Circulation Models ◽

Threshold Temperature ◽

Wave Characteristics

Abstract Regional climate model (RCM) simulations, driven by low and high climate-sensitivity coupled general circulation models (CGCMs) under various future emissions scenarios, were compared to projected changes in heat wave characteristics. The RCM downscaling reduces the CGCM biases in heat wave threshold temperature by a factor of 2, suggesting a higher credibility in the future projections. All of the RCM simulations suggest that there is a high probability of heat waves of unprecedented severity by the end of the twenty-first century if a high emissions path is followed. In particular, the annual 3-day heat wave temperature increases generally by 3°–8°C; the number of heat wave days increases by 30–60 day yr−1 over much of the western and southern United States with slightly smaller increases elsewhere; the variance spectra for intermediate, 3–7 days (prolonged, 7–14 days), temperature extremes increase (decrease) in the central (western) United States. If a lower emissions path is followed, then the outcomes range from quite small changes to substantial increases. In all cases, the mean temperature climatological shift is the dominant change in heat wave characteristics, suggesting that adaptation and acclimatization could reduce effects.

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Assessing the response of groundwater quantity and travel time distribution to 1.5, 2, and 3 °C global warming in a mesoscale central German basin

Hydrology and Earth System Sciences ◽

10.5194/hess-24-1511-2020 ◽

2020 ◽

Vol 24 (3) ◽

pp. 1511-1526

Author(s):

Miao Jing ◽

Rohini Kumar ◽

Falk Heße ◽

Stephan Thober ◽

Oldrich Rakovec ◽

...

Keyword(s):

Global Warming ◽

Travel Time ◽

General Circulation ◽

General Circulation Models ◽

Hydrologic Model ◽

Groundwater Model ◽

Groundwater Levels ◽

Ensemble Simulations ◽

Projected Change ◽

German Basin

Abstract. Groundwater is the biggest single source of high-quality freshwater worldwide, which is also continuously threatened by the changing climate. In this paper, we investigate the response of the regional groundwater system to climate change under three global warming levels (1.5, 2, and 3 ∘C) in a central German basin (Nägelstedt). This investigation is conducted by deploying an integrated modeling workflow that consists of a mesoscale hydrologic model (mHM) and a fully distributed groundwater model, OpenGeoSys (OGS). mHM is forced with climate simulations of five general circulation models under three representative concentration pathways. The diffuse recharges estimated by mHM are used as boundary forcings to the OGS groundwater model to compute changes in groundwater levels and travel time distributions. Simulation results indicate that groundwater recharges and levels are expected to increase slightly under future climate scenarios. Meanwhile, the mean travel time is expected to decrease compared to the historical average. However, the ensemble simulations do not all agree on the sign of relative change. Changes in mean travel time exhibit a larger variability than those in groundwater levels. The ensemble simulations do not show a systematic relationship between the projected change (in both groundwater levels and travel times) and the warming level, but they indicate an increased variability in projected changes with adjusting the enhanced warming level from 1.5 to 3 ∘C. Correspondingly, it is highly recommended to restrain the trend of global warming.

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A Model Study of Heat Waves over North America: Meteorological Aspects and Projections for the Twenty-First Century

Journal of Climate ◽

10.1175/jcli-d-11-00575.1 ◽

2012 ◽

Vol 25 (14) ◽

pp. 4761-4784 ◽

Cited By ~ 114

Author(s):

Ngar-Cheung Lau ◽

Mary Jo Nath

Keyword(s):

Twentieth Century ◽

North America ◽

Heat Wave ◽

General Circulation ◽

Heat Waves ◽

General Circulation Models ◽

Reanalysis Data ◽

First Century ◽

Twenty First Century ◽

The Impact

Abstract The characteristics of summertime heat waves in North America are examined using reanalysis data and simulations by two general circulation models with horizontal resolution of 50 and 200 km. Several “key regions” with spatially coherent and high amplitude fluctuations in daily surface air temperature are identified. The typical synoptic features accompanying warm episodes in these regions are described. The averaged intensity, duration, and frequency of occurrence of the heat waves in various key regions, as simulated in the two models for twentieth-century climate, are in general agreement with the results based on reanalysis data. The impact of climate change on the heat wave characteristics in various key regions is assessed by contrasting model runs based on a scenario for the twenty-first century with those for the twentieth century. Both models indicate considerable increases in the duration and frequency of heat wave episodes, and in number of heat wave days per year, during the twenty-first century. The duration and frequency statistics of the heat waves in the mid-twenty-first century, as generated by the model with 50-km resolution, can be reproduced by adding the projected warming trend to the daily temperature data for the late twentieth century, and then recomputing these statistics. The detailed evolution of the averaged intensity, duration, and frequency of the heat waves through individual decades of the twentieth and twenty-first centuries, as simulated and projected by the model with 200-km resolution, indicates that the upward trend in these heat wave measures should become apparent in the early decades of the twenty-first century.

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Climate Change and Extreme Temperature Trends in the Baja California Peninsula, Mexico

Air Soil and Water Research ◽

10.1177/11786221211010702 ◽

2021 ◽

Vol 14 ◽

pp. 117862212110107

Author(s):

Polioptro F Martínez-Austria ◽

José Alejandro Jano-Pérez

Keyword(s):

Climate Change ◽

Gulf Of California ◽

General Circulation ◽

Baja California ◽

Extreme Temperature ◽

General Circulation Models ◽

Baja California Peninsula ◽

Temperature Trends ◽

The Pacific ◽

Maximum Temperatures

Climate change is one of the greatest threats that our civilization is facing because increases in extreme temperatures severely affect humans, the economy, and ecosystems. General circulation models, which adequately predict climate change around the world, are less accurate at regional levels. Therefore, trends must be locally assessed, particularly in regions such as the Baja California Peninsula, which is a thin mass of land surrounded by the Pacific Ocean and the Gulf of California. Herein, we discuss extreme temperature trends in the Baja California Peninsula and whether they are statistically significant based on the Spearman’s nonparametric statistical test. For these purposes, 18 weather stations covering the entire region were analyzed, revealing that maximum temperatures for the hottest months are rising at a rate that is consistent with the RCP 8.5 scenario. Changes in minimum temperatures were also analyzed.

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