scholarly journals Kilometer-scale modeling projects a tripling of Alaskan convective storms in future climate

2020 ◽  
Vol 55 (11-12) ◽  
pp. 3543-3564
Author(s):  
Basile Poujol ◽  
Andreas F. Prein ◽  
Andrew J. Newman
Keyword(s):  
Rain Gauge ◽  
Future Climate ◽  
The Arctic ◽  
Climate Simulation ◽  
Climate Conditions ◽  
Convective Storms ◽  
Convective Systems ◽  
High Emission ◽  
High Emission Scenario ◽  
The Impact

Abstract Convective storms produce heavier downpours and become more intense with climate change. Such changes could be even amplified in high-latitudes since the Arctic is warming faster than any other region in the world and subsequently moistening. However, little attention has been paid to the impact of global warming on intense thunderstorms in high latitude continental regions, where they can produce flash flooding or ignite wildfires. We use a model with kilometer-scale grid spacing to simulate Alaska’s climate under present and end of the century high emission scenario conditions. The current climate simulation is able to capture the frequency and intensity of hourly precipitation compared to rain gauge data. We apply a precipitation tracking algorithm to identify intense, organized convective systems, which are projected to triple in frequency and extend to the northernmost regions of Alaska under future climate conditions. Peak rainfall rates in the core of the storms will intensify by 37% in line with atmospheric moisture increases. These results could have severe impacts on Alaska’s economy and ecology since floods are already the costliest natural disaster in central Alaska and an increasing number of thunderstorms could result in more wildfires ignitions.

scholarly journals Dynamic and Thermodynamic Impacts of Climate Change on Organized Convection in Alaska

2021 ◽  
Author(s):  
Basile Poujol ◽  
Andreas Prein ◽  
Caroline Muller ◽  
Maria Molina
Keyword(s):  
Climate Change ◽  
Relative Humidity ◽  
Deep Convection ◽  
Climate Change Impacts ◽  
Future Climate ◽  
Lower Latitude ◽  
Climate Conditions ◽  
Convective Systems ◽  
High Emission ◽  
Organized Convection

<p>Organized convective systems produce heavier downpours and can become more intense with climate change. While organized convection is well studied in the tropics and mid-latitudes, few studies have focused on the physics and climate change impacts of pan-Arctic convective systems, where they can produce flash flooding, landslides, or ignite wildfires.</p><p>We use a convection-permitting model to simulate Alaska’s climate under current and end of the century high emission scenario conditions. We apply a precipitation tracking algorithm to identify intense, organized convective systems, which are projected to triple in frequency and extend to the northernmost regions of Alaska under future climate conditions. The present study assesses the reasons for this rapid increase in organized convection by investigating dynamic and thermodynamic changes within future storms and their environments, in light of canonical existing theories for mid-latitude and tropical deep convection.</p><p> </p><p>In a future climate, more moisture originates from Arctic marine basins and relative humidity over continental Alaska is projected to increase due to sea ice loss, which is in sharp contrast to lower-latitude land regions that are expected to become drier. This increase in relative humidity favors the onset of organized convection through more unstable thermodynamic environments, increased low-level buoyancy, and weaker downdrafts.</p><p>Our confidence in these results is increased by showing that these changes can be analytically derived from basic physical laws. This suggests that organized thunderstorms might become more frequent in other pan-Arctic continental regions highlighting the uniqueness and vulnerability of these regions to climate change.</p>

Bias correction of extreme values of high resolution climate simulations for risk analysis.

2021 ◽  
Author(s):  
luis Augusto sanabria ◽  
Xuerong Qin ◽  
Jin Li ◽  
Robert Peter Cechet
Keyword(s):  
Climate Change ◽  
Bias Correction ◽  
Extreme Values ◽  
The Body ◽  
Future Climate ◽  
Return Periods ◽  
Climate Conditions ◽  
Mitigation And Adaptation ◽  
Climate Simulations ◽  
The Impact

Abstract Most climatic models show that climate change affects natural perils' frequency and severity. Quantifying the impact of future climate conditions on natural hazard is essential for mitigation and adaptation planning. One crucial factor to consider when using climate simulations projections is the inherent systematic differences (bias) of the modelled data compared with observations. This bias can originate from the modelling process, the techniques used for downscaling of results, and the ensembles' intrinsic variability. Analysis of climate simulations has shown that the biases associated with these data types can be significant. Hence, it is often necessary to correct the bias before the data can be reliably used for further analysis. Natural perils are often associated with extreme climatic conditions. Analysing trends in the tail end of distributions are already complicated because noise is much more prominent than that in the mean climate. The bias of the simulations can introduce significant errors in practical applications. In this paper, we present a methodology for bias correction of climate simulated data. The technique corrects the bias in both the body and the tail of the distribution (extreme values). As an illustration, maps of the 50 and 100-year Return Period of climate simulated Forest Fire Danger Index (FFDI) in Australia are presented and compared against the corresponding observation-based maps. The results show that the algorithm can substantially improve the calculation of simulation-based Return Periods. Forthcoming work will focus on the impact of climate change on these Return Periods considering future climate conditions.

scholarly journals How does downward planetary wave coupling affect polar stratospheric ozone in the Arctic winter stratosphere?

2017 ◽  
Vol 17 (3) ◽  
pp. 2437-2458 ◽  
Author(s):  
Sandro W. Lubis ◽  
Vered Silverman ◽  
Katja Matthes ◽  
Nili Harnik ◽  
Nour-Eddine Omrani ◽  
...  
Keyword(s):  
Ozone Concentration ◽  
Planetary Wave ◽  
Wave Reflection ◽  
Stratospheric Ozone ◽  
Polar Vortex ◽  
The Arctic ◽  
Climate Simulation ◽  
Residual Circulation ◽  
Wave Flux ◽  
The Impact

Abstract. It is well established that variable wintertime planetary wave forcing in the stratosphere controls the variability of Arctic stratospheric ozone through changes in the strength of the polar vortex and the residual circulation. While previous studies focused on the variations in upward wave flux entering the lower stratosphere, here the impact of downward planetary wave reflection on ozone is investigated for the first time. Utilizing the MERRA2 reanalysis and a fully coupled chemistry–climate simulation with the Community Earth System Model (CESM1(WACCM)) of the National Center for Atmospheric Research (NCAR), we find two downward wave reflection effects on ozone: (1) the direct effect in which the residual circulation is weakened during winter, reducing the typical increase of ozone due to upward planetary wave events and (2) the indirect effect in which the modification of polar temperature during winter affects the amount of ozone destruction in spring. Winter seasons dominated by downward wave reflection events (i.e., reflective winters) are characterized by lower Arctic ozone concentration, while seasons dominated by increased upward wave events (i.e., absorptive winters) are characterized by relatively higher ozone concentration. This behavior is consistent with the cumulative effects of downward and upward planetary wave events on polar stratospheric ozone via the residual circulation and the polar temperature in winter. The results establish a new perspective on dynamical processes controlling stratospheric ozone variability in the Arctic by highlighting the key role of wave reflection.

scholarly journals Use of a Rain Gauge Network to Infer the Influence of Environmental Factors on the Propagation of Quasi-Linear Convective Systems in West Africa

2007 ◽  
Vol 22 (5) ◽  
pp. 1016-1030 ◽  
Author(s):  
Jon M. Schrage ◽  
Andreas H. Fink
Keyword(s):  
Environmental Factors ◽  
Propagation Rate ◽  
Rain Gauge ◽  
West African ◽  
Squall Line ◽  
Propagation Characteristics ◽  
Convective Systems ◽  
Squall Lines ◽  
Radiosonde Station ◽  
The Impact

Abstract The West African squall line is a key quasi-linear storm system that brings much of the precipitation observed in the data-poor Sudanian climate zone. Squall lines propagate at a wide range of speeds and headings, but the lack of operational radar stations in the region makes quantifying the propagation of the squall lines difficult. A new method of estimating the propagation rate and heading for squall lines is proposed. Based on measurements of the time of onset of precipitation (OOP) at a network of rain gauge stations, an estimate of the propagation characteristics of the squall line can be inferred. By combining estimates of propagation rate with upper-air observations gathered at a nearby radiosonde station, the impact of various environmental factors on the propagation characteristics of West African squall lines is inferred. Results suggest that the propagation speed for West African squall lines is related to the conditions at midtropospheric levels, where dry air and an enhanced easterly flow favor faster propagation. Northerly anomalies at these levels are also associated with faster propagation. When applied to West African squall lines, the correlations between these environmental factors and the speed of propagation are significantly higher than those of methods developed for mesoscale convective systems in other parts of the world.

First assessment of biomass and abundance of cephalopods Rossia palpebrosa and Gonatus fabricii in the Barents Sea

2016 ◽  
Vol 97 (8) ◽  
pp. 1605-1616 ◽  
Author(s):  
Alexey V. Golikov ◽  
Rushan M. Sabirov ◽  
Pavel A. Lubin
Keyword(s):  
Deep Water ◽  
Barents Sea ◽  
World Ocean ◽  
The Arctic ◽  
Arctic Ecosystems ◽  
Climate Conditions ◽  
Quantitative Distribution ◽  
Maximum Biomass ◽  
The Barents Sea ◽  
The Impact

Studies on the quantitative distribution of cephalopods in the Arctic are limited, and almost completely absent for the Barents Sea. It is known that the most abundant cephalopods in the Arctic are Rossia palpebrosa and Gonatus fabricii. Their biomass and abundance have been assessed for the first time in the Barents Sea and adjacent waters. The maximum biomass of R. palpebrosa in the Barents Sea was 6.216–6.454 thousand tonnes with an abundance of 521.5 million specimens. Increased densities of biomass were annually registered in the north-eastern parts of the Barents Sea. The maximum biomass of G. fabricii in the Barents Sea was 24.797 thousand tonnes with an abundance of 1.705 billion specimens. The areas with increased density of biomass (higher than 100 kg km−2) and abundance (more than 10,000 specimens km−2) were concentrated in deep-water troughs in the marginal parts of the Barents Sea and in adjacent deep-water areas. The biomass and abundance of R. palpebrosa and G. fabricii in the Barents Sea were much lower than those of major taxa of invertebrates and fish and than those of cephalopods in other parts of the World Ocean. It has been suggested that the importance of cephalopods in the Arctic ecosystems, at least in terms of quantitative distribution, could be somewhat lower than in the Antarctic or the tropics. Despite the impact of ongoing warming of the Arctic on the distribution of cephalopods being described repeatedly already, no impact of the current year's climate on the studied species was found. The only exception was the abundance of R. palpebrosa, which correlated with the current year's climate conditions.

scholarly journals Impact of Future Climate and Vegetation on the Hydrology of an Arctic Headwater Basin at the Tundra–Taiga Transition

2019 ◽  
Vol 20 (2) ◽  
pp. 197-215 ◽  
Author(s):  
Sebastian A. Krogh ◽  
John W. Pomeroy
Keyword(s):  
Climate Change ◽  
Snow Accumulation ◽  
Future Climate ◽  
The Arctic ◽  
Climate Projections ◽  
Mean Annual Temperature ◽  
Permafrost Degradation ◽  
Blowing Snow ◽  
Projected Changes ◽  
The Impact

Abstract The rapidly warming Arctic is experiencing permafrost degradation and shrub expansion. Future climate projections show a clear increase in mean annual temperature and increasing precipitation in the Arctic; however, the impact of these changes on hydrological cycling in Arctic headwater basins is poorly understood. This study investigates the impact of climate change, as represented by simulations using a high-resolution atmospheric model under a pseudo-global-warming configuration, and projected changes in vegetation, using a spatially distributed and physically based Arctic hydrological model, on a small headwater basin at the tundra–taiga transition in northwestern Canada. Climate projections under the RCP8.5 emission scenario show a 6.1°C warming, a 38% increase in annual precipitation, and a 19 W m−2 increase in all-wave annual irradiance over the twenty-first century. Hydrological modeling results suggest a shift in hydrological processes with maximum peak snow accumulation increasing by 70%, snow-cover duration shortening by 26 days, active layer deepening by 0.25 m, evapotranspiration increasing by 18%, and sublimation decreasing by 9%. This results in an intensification of the hydrological regime by doubling discharge volume, a 130% increase in spring runoff, and earlier and larger peak streamflow. Most hydrological changes were found to be driven by climate change; however, increasing vegetation cover and density reduced blowing snow redistribution and sublimation, and increased evaporation from intercepted rainfall. This study provides the first detailed investigation of projected changes in climate and vegetation on the hydrology of an Arctic headwater basin, and so it is expected to help inform larger-scale climate impact studies in the Arctic.

scholarly journals Expected Changes to Alpine Pastures in Extent and Composition under Future Climate Conditions

Agronomy ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 926
Author(s):  
Camilla Dibari ◽  
Sergi Costafreda-Aumedes ◽  
Giovanni Argenti ◽  
Marco Bindi ◽  
Federico Carotenuto ◽  
...  
Keyword(s):  
Climate Change ◽  
Biodiversity Loss ◽  
Future Climate ◽  
Pastoral Systems ◽  
Pastoral System ◽  
Climate Conditions ◽  
Nardus Stricta ◽  
Livestock Feeding ◽  
The Alps ◽  
The Impact

As the basis of livestock feeding and related performances, pastures evolution and dynamics need to be carefully monitored and assessed, particularly in the Alps where the effects of land abandonment are further amplified by climate change. As such, increases in temperature associated with changes in precipitation patterns and quantity are leading to modifications of grassland extent and composition with consequences on the pastoral systems. This study applied a machine learning approach (Random Forest) and GIS techniques to map the suitability of seven pasture macro types most representative of the Italian Alps and simulated the impact of climate change on their dynamics according to two future scenarios (RCP4.5, 8.5), two time-slices (2011–2040, 2041–2070), and three RCMs (Aladin, CMCC, ICTP). Results indicated that (i) the methodology was robust to map the current suitability of pasture macro types (mean accuracy classification = 98.7%), so as to predict the expected alterations due to climate change; (ii) future climate will likely reduce current extend of suitable pasture (−30% on average) and composition, especially for most niche ecosystems (i.e., pastures dominated by Carex firma and Festuca gr. Rubra); (iii) areas suited to hardier but less palatable pastures (i.e., dominated by Nardus stricta and xeric species) will expand over the Alps in the near future. These impacts will likely determine risks for biodiversity loss and decreases of pastoral values for livestock feeding, both pivotal aspects for maintaining the viability and profitability of the Alpine pastoral system as a whole.

scholarly journals Evaluating Nature-Based Solution for Flood Reduction in Spercheios River Basin under Current and Future Climate Conditions

2021 ◽  
Vol 13 (7) ◽  
pp. 3885
Author(s):  
Christos Spyrou ◽  
Michael Loupis ◽  
Νikos Charizopoulos ◽  
Ilektra Apostolidou ◽  
Angeliki Mentzafou ◽  
...  
Keyword(s):  
Climate Change ◽  
River Basin ◽  
Maximum Velocity ◽  
Weather Conditions ◽  
Future Climate ◽  
Future Climate Change ◽  
Climate Change Scenarios ◽  
Climate Conditions ◽  
The Impact

Nature-based solutions (NBS) are being deployed around the world in order to address hydrometeorological hazards, including flooding, droughts, landslides and many others. The term refers to techniques inspired, supported and copied from nature, avoiding large constructions and other harmful interventions. In this work the development and evaluation of an NBS applied to the Spercheios river basin in Central Greece is presented. The river is susceptible to heavy rainfall and bank overflow, therefore the intervention selected is a natural water retention measure that aims to moderate the impact of flooding and drought in the area. After the deployment of the NBS, we examine the benefits under current and future climate conditions, using various climate change scenarios. Even though the NBS deployed is small compared to the rest of the river, its presence leads to a decrease in the maximum depth of flooding, maximum velocity and smaller flooded areas. Regarding the subsurface/groundwater storage under current and future climate change and weather conditions, the NBS construction seems to favor long-term groundwater recharge.

More extreme El Niño events reduce ocean carbon uptake in the future

2021 ◽  
Author(s):  
Enhui Liao ◽  
Laure Resplandy ◽  
Junjie Liu ◽  
Kevin Bowman
Keyword(s):  
Biogeochemical Model ◽  
Historical Period ◽  
Terrestrial Biosphere ◽  
The Future ◽  
Thermally Driven ◽  
High Emission ◽  
Ocean Carbon ◽  
High Emission Scenario ◽  
Flux Response ◽  
The Impact

<p>El Niño events weaken the strong natural oceanic source of CO<sub>2</sub> in the Tropical Pacific Ocean, partly offsetting the simultaneous release of CO<sub>2</sub> from the terrestrial biosphere during these events. Yet, uncertainties in the magnitude of this ocean response and how it will respond to the projected increase in extreme El Niño in the future (Cai et al., 2014) limit our understanding of the global carbon cycle and its sensitivity to climate. Here, we examine the mechanisms controlling the air-sea CO<sub>2</sub> flux response to El Niño events and how it will evolve in the future, using multidecadal ocean pCO<sub>2</sub> observations in conjunction with CMIP6 Earth system models (ESMs) and a state‐of‐the‐art ocean biogeochemical model. We show that the magnitude, spatial extent, and duration of the anomalous ocean CO<sub>2</sub> drawdown increased with El Niño intensity in the historical period. However, this relationship reverses in the CMIP6 projections under the high emission scenario. ESMs project more intense El Niño events, but weaker CO<sub>2</sub> flux anomalies in the future. This unexpected response is controlled by two factors: a stronger compensation between thermally-driven outgassing and non-thermal drawdown (56% of the signal); and less pronounced wind anomalies limiting the impact of El Niño on air-sea CO<sub>2</sub> exchanges (26% of the signal). El Niños should no longer reinforce the net global oceanic sink in the future, but have a near-neutral effect or even release CO<sub>2</sub> to the atmosphere, reinforcing the concurrent release of CO<sub>2</sub> from the terrestrial biosphere.</p>

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