Future changes in atmospheric rivers and extreme precipitation in Norway

Atmospheric rivers (AR) are associated with flooding events in Norway, like the flood that impacted Fl&#229;m in 2014. We assess trends in Norwegian AR characteristics, and the influence of AR variability on extreme precipitation in Norway. After evaluating the global climate model, EC-Earth, compared to the ERA-Interim reanalysis, we show that ARs increase in both intensity and frequency by the end of the century. In two regions on the west coast, the majority of winter precipitation maxima are associated with AR events (> 80% of cases). A non-stationary extreme value analysis indicates that the magnitude of extreme precipitation events in these regions is associated with AR intensity. Indeed, the 1-in-20 year extreme event is 17% larger when the AR-intensity is high, compared to when it is low. Finally, we find that the region mean temperature during winter AR events increases in the future. In the future, when the climate is generally warmer, AR days will tend to make landfall when the temperature is above the freezing point. The partitioning of more precipitation as rain, rather than snow, can have severe impacts on flooding and water resource management in Norway.

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Projected Changes in Precipitation Extremes over Shaanxi Province, China, in the 21st Century

Advances in Meteorology ◽

10.1155/2020/1808404 ◽

2020 ◽

Vol 2020 ◽

pp. 1-13

Author(s):

Ling Li ◽

Ziniu Xiao ◽

Shuxiang Luo ◽

Aili Yang

Keyword(s):

Global Warming ◽

21St Century ◽

Extreme Precipitation ◽

Climate Model ◽

Global Climate Model ◽

Precipitation Extremes ◽

Shaanxi Province ◽

Extreme Precipitation Events ◽

The Future ◽

Precipitation Events

Extreme precipitation events, which have intensified with global warming, will have a pernicious influence on society. It would be desirable to understand how they will evolve in the future as global warming becomes more serious with time. Thus, the primary objective of this study is to provide a comprehensive understanding of the changing characteristics of the precipitation extremes in the 21st century over Shaanxi Province, a climate-sensitive and environmentally fragile area located in the east of northwestern China, based on a consecutive simulation of the 21st century conducted by the regional climate model RegCM4 forced by the global climate model HadGEM2-ES at high resolution under middle emission scenario of the Representative Concentration Pathway 4.5 (RCP4.5). Basic validation of the model performance was carried out, and six extreme precipitation indices (EPIs) were used to assess the intensity and frequency of the extreme precipitation events over Shaanxi Province. The results show that RegCM4 reproduces the observed characteristics of extreme precipitation events over Shaanxi Province well. Overall for the domain, the EPIs excluding consecutive dry days (CDD) have a growing tendency during 1980–2098 although they exhibit spatial variability over Shaanxi Province. Some areas in the arid northern Shaanxi may have more heavy rainfalls by the middle of the 21st century but less wet extreme events by the end of the 21st century. And the humid central and southern regions would suffer more precipitation-related natural hazards in the future.

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Changing seasonality of moderate and extreme precipitation events in the Alps

Natural Hazards and Earth System Science ◽

10.5194/nhess-18-2047-2018 ◽

2018 ◽

Vol 18 (7) ◽

pp. 2047-2056 ◽

Cited By ~ 20

Author(s):

Stefan Brönnimann ◽

Jan Rajczak ◽

Erich M. Fischer ◽

Christoph C. Raible ◽

Marco Rohrer ◽

...

Keyword(s):

Extreme Precipitation ◽

Climate Model ◽

Global Climate Model ◽

Model Simulations ◽

Extreme Precipitation Events ◽

Rate Of Increase ◽

Decadal Scale ◽

The Future ◽

The Impact ◽

Precipitation Events

Abstract. The intensity of precipitation events is expected to increase in the future. The rate of increase depends on the strength or rarity of the events; very strong and rare events tend to follow the Clausius–Clapeyron relation, whereas weaker events or precipitation averages increase at a smaller rate than expected from the Clausius–Clapeyron relation. An often overlooked aspect is seasonal occurrence of such events, which might change in the future. To address the impact of seasonality, we use a large ensemble of regional and global climate model simulations, comprising tens of thousands of model years of daily temperature and precipitation for the past, present, and future. In order to make the data comparable, they are quantile mapped to observation-based time series representative of the Aare catchment in Switzerland. Model simulations show no increase in annual maximum 1-day precipitation events (Rx1day) over the last 400 years and an increase of 10 %–20 % until the end of the century for a strong (RCP8.5) forcing scenario. This fits with a Clausius–Clapeyron scaling of temperature at the event day, which increases less than annual mean temperature. An important reason for this is a shift in seasonality. Rx1day events become less frequent in late summer and more frequent in early summer and early autumn, when it is cooler. The seasonality shift is shown to be related to summer drying. Models with decreasing annual mean or summer mean precipitation show this behaviour more strongly. The highest Rx1day per decade, in contrast, shows no change in seasonality in the future. This discrepancy implies that decadal-scale extremes are thermodynamically limited; conditions conducive to strong events still occur during the hottest time of the year on a decadal scale. In contrast, Rx1day events are also limited by other factors. Conducive conditions are not reached every summer in the present, and even less so in the future. Results suggest that changes in the seasonal cycle need to be accounted for when preparing for moderately extreme precipitation events and assessing their socio-economic impacts.

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Changing seasonality of moderate and extreme precipitation events in the Alps

10.5194/nhess-2018-55 ◽

2018 ◽

Author(s):

Stefan Brönnimann ◽

Jan Rajczak ◽

Erich Fischer ◽

Christoph C. Raible ◽

Marco Rohrer ◽

...

Keyword(s):

Extreme Precipitation ◽

Climate Model ◽

Global Climate Model ◽

Model Simulations ◽

Extreme Precipitation Events ◽

Rate Of Increase ◽

Decadal Scale ◽

The Future ◽

The Impact ◽

Precipitation Events

Abstract. The intensity of precipitation events is expected to increase in the future. The rate of increase depends on the strength or rarity of the events; very strong and rare events tend to follow the Clausius-Clapeyron relation, whereas weaker events or precipitation averages do not. An often overlooked aspect is seasonal occurrence of such events, which might change in the future. To address the impact of seasonality, we use a large ensemble of regional and global climate model simulations, comprising tens of thousands of model years of daily temperature and precipitation for the past, present and future. In order to make the data comparable, they are quantile-mapped to observation-based time series representative of the Aare catchment in Switzerland. Model simulations show no increase in annual maximum 1-day precipitation events (Rx1day) over the last 400 yrs and an increase of 10–20 % until the end of the century for a strong (RCP8.5) forcing scenario. This fits with a Clausius-Clapeyron scaling of temperature at the event day, which increases less than annual mean temperature. An important reason for this is a shift in seasonality. Rx1day events become less frequent in late summer and more frequent in early summer and early fall, when it is cooler. The seasonality shift is shown to be related to summer drying. Models with decreasing annual mean or summer mean precipitation show this behavior more strongly. The highest Rx1day per decade, in contrast, shows no change in seasonality in the future. This discrepancy implies that decadal-scale extremes are thermodynamically limited; conditions conducive to strong events still occur during hottest time of the year on a decadal scale. In contrast, Rx1day events are also limited by other factors. Conducive conditions are not reached every summer in the present, and even less so in the future. Results suggest that changes in the seasonal cycle need to be accounted for when preparing for moderately extreme precipitation events and assessing their socio-economic impacts.

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Attribution of changes in the trend and temporal non-uniformity of extreme precipitation events in Central Asia

Scientific Reports ◽

10.1038/s41598-021-94486-w ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Shan Zou ◽

Jilili Abuduwaili ◽

Weili Duan ◽

Jianli Ding ◽

Philippe De Maeyer ◽

...

Keyword(s):

Central Asia ◽

Extreme Precipitation ◽

Radiative Forcing ◽

Water Resource Management ◽

Climate Model ◽

Global Climate Model ◽

Anthropogenic Forcing ◽

Extreme Precipitation Events ◽

The Impact ◽

Precipitation Events

AbstractExtreme precipitation events exhibit an increasing trend for both the frequency and magnitude on global and regional scales and it has already proven the impact of man-made global warming on the extreme precipitation amplification. Based on the observed datasets and global climate model (GCM) output, this study has evaluated the impact from anthropogenic forcing on the trend and temporal non-uniformity (i.e. increase in unevenness or disparity) of the precipitation amounts (PRCPTOT), extremes (R95p and RX5day) and intensity (SDII) in Central Asia (CA) from 1961 to 2005. Results indicate that radiative forcing changes, mainly driven by human activities, have significantly augmented the extreme precipitation indices in CA. The median trend with the influence of anthropogenic activities for the PRCPTOT, SDII, R95p and RX5day amounted to 2.19 mm/decade, 0.019 mm/decade, 1.39 mm/decade and 0.21 mm/decade during the study period, respectively. A statistically insignificant decrease in non-uniformity was noticed for the PRCPTOT, SDII and RX5day in Central CA (CCA) and Western CA (WCA), while Eastern CA (ECA) was the only region with a statistically significant increase in non-uniformity of the PRCPTOT, SDII, R95p and RX5day by 4.22%, 3.98%, 3.73% and 3.97%, respectively from 1961 to 2005 due to anthropogenic forcing. These results reflect the difference in various regions regarding the impact of anthropogenic forcing on the non-uniformity of extreme precipitation events in CA, which might help to fully understand the role of anthropogenic forcing in the changes of the precipitation extremes in CA and contribute to the development of water resource management strategies.

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Simulation of Extreme Precipitation in Four Climate Regions in China by General Circulation Models (GCMs): Performance and Projections

Water ◽

10.3390/w13111509 ◽

2021 ◽

Vol 13 (11) ◽

pp. 1509

Author(s):

Mengru Zhang ◽

Xiaoli Yang ◽

Liliang Ren ◽

Ming Pan ◽

Shanhu Jiang ◽

...

Keyword(s):

Extreme Precipitation ◽

General Circulation ◽

Global Climate ◽

Summer Precipitation ◽

General Circulation Models ◽

Cumulative Distribution ◽

Extreme Precipitation Events ◽

Increasing Trend ◽

The Future ◽

Semi Arid

In the context of global climate change, it is important to monitor abnormal changes in extreme precipitation events that lead to frequent floods. This research used precipitation indices to describe variations in extreme precipitation and analyzed the characteristics of extreme precipitation in four climatic (arid, semi-arid, semi-humid and humid) regions across China. The equidistant cumulative distribution function (EDCDF) method was used to downscale and bias-correct daily precipitation in eight Coupled Model Intercomparison Project Phase 5 (CMIP5) general circulation models (GCMs). From 1961 to 2005, the humid region had stronger and longer extreme precipitation compared with the other regions. In the future, the projected extreme precipitation is mainly concentrated in summer, and there will be large areas with substantial changes in maximum consecutive 5-day precipitation (Rx5) and precipitation intensity (SDII). The greatest differences between two scenarios (RCP4.5 and RCP8.5) are in semi-arid and semi-humid areas for summer precipitation anomalies. However, the area of the four regions with an increasing trend of extreme precipitation is larger under the RCP8.5 scenario than that under the RCP4.5 scenario. The increasing trend of extreme precipitation in the future is relatively pronounced, especially in humid areas, implying a potential heightened flood risk in these areas.

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The effect of climate change on urban drainage: an evaluation based on regional climate model simulations

Water Science & Technology ◽

10.2166/wst.2006.592 ◽

2006 ◽

Vol 54 (6-7) ◽

pp. 9-15 ◽

Cited By ~ 41

Author(s):

M. Grum ◽

A.T. Jørgensen ◽

R.M. Johansen ◽

J.J. Linde

Keyword(s):

Climate Change ◽

Extreme Precipitation ◽

Climate Model ◽

Regional Climate ◽

Rain Gauge ◽

Urban Drainage ◽

Extreme Precipitation Events ◽

Rainfall Extremes ◽

The Future ◽

Precipitation Events

That we are in a period of extraordinary rates of climate change is today evident. These climate changes are likely to impact local weather conditions with direct impacts on precipitation patterns and urban drainage. In recent years several studies have focused on revealing the nature, extent and consequences of climate change on urban drainage and urban runoff pollution issues. This study uses predictions from a regional climate model to look at the effects of climate change on extreme precipitation events. Results are presented in terms of point rainfall extremes. The analysis involves three steps: Firstly, hourly rainfall intensities from 16 point rain gauges are averaged to create a rain gauge equivalent intensity for a 25 × 25 km square corresponding to one grid cell in the climate model. Secondly, the differences between present and future in the climate model is used to project the hourly extreme statistics of the rain gauge surface into the future. Thirdly, the future extremes of the square surface area are downscaled to give point rainfall extremes of the future. The results and conclusions rely heavily on the regional model's suitability in describing extremes at time-scales relevant to urban drainage. However, in spite of these uncertainties, and others raised in the discussion, the tendency is clear: extreme precipitation events effecting urban drainage and causing flooding will become more frequent as a result of climate change.

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Climate change attribution with large ensembles

10.5194/egusphere-egu21-3404 ◽

2021 ◽

Author(s):

Megan Kirchmeier-Young ◽

Xuebin Zhang ◽

Hui Wan

Keyword(s):

Extreme Precipitation ◽

Extreme Event ◽

Extreme Temperature ◽

Anthropogenic Forcing ◽

Robust Detection ◽

Continental Scale ◽

Extreme Precipitation Events ◽

Event Attribution ◽

Large Ensembles ◽

Precipitation Events

The large sample sizes from single-model large ensembles are beneficial for a robust attribution of climate changes to anthropogenic forcing. This presentation will review examples using large ensembles in two types of attribution:&#160; standard detection and attribution of spatio-temporal changes and extreme event attribution. First, increases in extreme precipitation have been attributed to anthropogenic forcing at large scales (global and hemispheric). We present results from a study that used three large ensembles, including two Earth System Models and one Regional Climate Model, to find a robust detection of a combined anthropogenic and natural forcing signal in the intensification of extreme precipitation at the continental scale and some regional scales in North America. Second, we use six large ensembles to assess the robustness of the attribution of extreme temperature and precipitation events. An event attribution framework is used and each large ensemble is treated as a perfect model. Robustness of the attribution is defined based on consistent agreement between the different models on a significant change in the probability of an event with the inclusion of anthropogenic forcing. We demonstrate that the attribution of extreme temperature events is robust. Meanwhile, the attribution of extreme precipitation events becomes robust in many regions under additional warming, but uncertainties pertaining to changes in atmospheric dynamics hinder attribution confidence in other regions. We also demonstrate that smaller ensembles bring larger uncertainty to event attribution.

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At-site and regional frequency analysis of extreme precipitation from radar-based estimates

10.5194/hess-2017-150 ◽

2017 ◽

Author(s):

Edouard Goudenhoofdt ◽

Laurent Delobbe ◽

Patrick Willems

Keyword(s):

Confidence Interval ◽

Frequency Analysis ◽

Extreme Precipitation ◽

Rain Gauge ◽

Regional Frequency Analysis ◽

Extreme Value Analysis ◽

Value Analysis ◽

Rain Gauges ◽

Rainfall Extremes ◽

Regional Frequency

Abstract. In Belgium, only rain gauge time-series have been used so far to study extreme precipitation at a given location. In this paper, the potential of a 12-year quantitative precipitation estimation (QPE) from a single weather radar is evaluated. For the period 2005–2016, independent sliding 1 h and 24 h rainfall extremes from automatic rain gauges and collocated radar estimates are compared. The extremes are fitted to the exponential distribution using regression in QQ-plots with a threshold rank which minimises the mean squared error. A basic radar product used as reference exhibits unrealistic high extremes and is not suitable for extreme value analysis. For 24 h rainfall extremes, which occur partly in winter, the radar-based QPE needs a bias correction. A few missing events are caused by the wind drift of convective cells and strong radar signal attenuation. Differences between radar and gauge values are caused by spatial and temporal sampling, gauge rainfall underestimations and radar errors due to the relation between reflectivity and rain rate. Nonetheless the fit to the QPE data is within the confidence interval of the gauge fit, which remains large due to the short study period. A regional frequency analysis is performed on radar data within 20 km of the locations of 4 rain gauges with records from 1965 to 2008. Assuming that the extremes are correlated within the region, the fit to the two closest rain gauge data is within the confidence interval of the radar fit, which is small due to the sample size. In Brussels, the extremes on the period 1965–2008 from a rain gauge are significantly lower than the extremes from an automatic gauge and the radar on the period 2005–2016. For 1 h duration, the location parameter varies slightly with topography and the scale parameter exhibits some variations from region to region. The radar-based extreme value analysis can be extended to other durations.

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Applying a storyline approach to explore the impact of future Atmospheric River induced floods in western Norway

10.5194/egusphere-egu21-8309 ◽

2021 ◽

Author(s):

Trine Jahr Hegdahl ◽

Kolbjørn Engeland ◽

Malte Müller ◽

Jana Sillman

Keyword(s):

Extreme Precipitation ◽

Initial Conditions ◽

Future Climate ◽

Meteorological Forcing ◽

Extreme Precipitation Events ◽

Western Norway ◽

Current Climate ◽

The Future ◽

Climate Events ◽

Precipitation Events

Atmospheric rivers (AR) are responsible for the most extreme precipitation events causing devastating landslides and floods in western Norway. In this study an event-based storyline approach is used to compare the flood impact of extreme AR events in a warmer climate to those of the current climate.&#160; The four most extreme precipitation events were selected from 30 years of present and future climate simulations from the high-resolution global climate model, the EC-Earth model. For each of the four events, EC-Earth was rerun creating 10 perturbed realizations. A regional convective permitting weather prediction model, AROME-MetCoOp, was used to further downscale the events, and thereafter the operational Norwegian flood-forecasting model was used to estimate the flood levels for 37 catchments in western Norway. The magnitude and the spatial impact were analyzed, and different hydrological initial conditions, which affect the total flooding, were analyzed.The results show that more catchments were affected with larger floods in the future climate events compared to the current climate events. In addition, the combination of multiple realizations of meteorological forcing and different hydrological initial conditions, for example soil saturation and snow storage, were important for the estimation of the maximum flood level. The meteorological forcing had the highest overall effect on flood magnitude; however, varying and depending on event and catchment. Finally, operational flood warning levels were used to visualize the difference between future and current climate flood events. Applying a setup similar to the one used operationally and relating the future events to known current events associated with ARs, enables a common reference and ease communication with end-users and decision makers.

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Trends, change points and spatial variability in extreme precipitation events from 1961 to 2017 in China

Hydrology Research ◽

10.2166/nh.2020.095 ◽

2020 ◽

Vol 51 (3) ◽

pp. 484-504 ◽

Cited By ~ 3

Author(s):

Linchao Li ◽

Yufeng Zou ◽

Yi Li ◽

Haixia Lin ◽

De Li Liu ◽

...

Keyword(s):

Extreme Precipitation ◽

Extreme Event ◽

Heavy Precipitation ◽

Kendall Test ◽

Temporal Variations ◽

Change Points ◽

Monthly Precipitation ◽

Flood Peak ◽

Extreme Precipitation Events ◽

Precipitation Events

Abstract Extreme precipitation events vary with different sub-regions, sites and years and show complex characteristics. In this study, the temporal variations, trends with significance and change points in the annual time series of 10 extreme precipitation indices (EPIs) at 552 sites and in seven sub-regions were analyzed using the modified Mann–Kendall test and sequential Mann–Kendall analysis. Three representative (extremely wet, normal and extremely dry) years from 1961 to 2017 were selected by the largest, 50%, and smallest empirical frequency values in China. The spatiotemporal changes in the EPIs during the three representative years were analyzed in detail. The results showed that during 1961–2017, both the consecutive wet or dry days decreased significantly, while the number of heavy precipitation days had no significant trend, and the other seven wet EPIs increased insignificantly. The abrupt change years of the 10 EPIs occurred 32 and 40 times from 1963 to 1978 and from 1990 to 2016, respectively, regardless of sub-region. The extremely dry (or wet) events mainly occurred in western (or southwestern) China, implying a higher extreme event risk. The extremely wet, normal and extremely dry events from 1961 to 2017 occurred in 2016, 1997 and 2011 with empirical frequencies of 1.7%, 50% and 98.3%, respectively. In addition, 1998 was the second-most extremely wet year (empirical frequency was 3.7%). The monthly precipitation values were larger from February to August in 1998, forming a much earlier flood peak than that of 2016. The 10 EPIs had close connections with Normalized Difference Vegetation Indexes during the 12 months of 1998 and 2016. This study provides useful references for disaster prevention in China.

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