Solar forcing on the Northern Hemisphere weather and climate extremes during summer

Weather And Climate ◽

Upper Level

The effects of solar irradiance forcing on weather and climate extremes have received relatively less attention compared to the solar-induced changes in the mean climate. In this respect, here we investigate the possible impact of solar irradiance forcing on the Northern Hemisphere extreme weather and climate variability during summer, from a potential vorticity (PV) perspective. The generation of severe weather events in the extra-tropical regions is often related to intrusions of high PV originating from the polar lower stratosphere. Various two-dimensional PV indices, similar to those characterizing surface temperature and precipitation extremes, are defined to measure the frequency of upper level PV intrusion events. Based on long-term reanalysis data, we show that upper level high PV intrusions over Asia (Europe) are more (less) frequent during high relatively to low solar irradiance summers. Consistent with this PV pattern more (less) frequent surface extreme precipitation events are recorded during high relative to low solar irradiance summers in Asia (Europe). Patterns in the frequency of extreme temperatures are largely opposite to the corresponding extreme precipitation. Furthermore, extreme climate anomaly patterns associated with high solar irradiance forcing are similar to the corresponding patterns associated with strong monsoon circulation over Asia during summer. A preliminary analysis reveals the dominant role of upper level solar related PV anomalies in generation of extreme precipitation in the Asian monsoon region during high solar irradiance summers. A persistent blocking like circulation in the Caspian Sea region during low solar irradiance summers is associated more frequent high PV intrusions and extreme precipitation over Europe. The stability of the solar related extreme precipitation and temperature patterns in the last millennium perspective is also discussed based on proxy data as well as model simulations.&#160;

A complex network analysis of extreme cyclones in the Arctic

10.5194/egusphere-egu21-3984 ◽

2021 ◽

Author(s):

Dörthe Handorf ◽

Ozan Sahin ◽

Annette Rinke ◽

Jürgen Kurths

Keyword(s):

Complex Network ◽

Northern Hemisphere ◽

Extreme Events ◽

Geopotential Height ◽

Winter Season ◽

Climate Extremes ◽

The Arctic ◽

Weather And Climate ◽

Class 1 ◽

Height Fields

Under the rapid and amplified warming of the Arctic, changes in the occurrence of Arctic weather and climate extremes are evident which have substantial cryospheric and biophysical impacts like floods, droughts, coastal erosion or wildfires. Furthermore, these changes in weather and climate extremes have the potential to further amplify Arctic warming.&#160; Here we study extreme cyclone events in the Arctic, which often occur during winter and are associated with extreme warming events that are caused by cyclone-related heat and moisture transport into the Arctic. In that way Arctic extreme cyclones have the potential to retard sea-ice growth in autumn and winter or to initiate an earlier melt-season onset.&#160; To get a better understanding of these extreme cyclones and their occurrences in the Arctic, it is important to reveal the related atmospheric teleconnection patterns and understand their underlying mechanisms. In this study, the methodology of complex networks is used to identify teleconnections associated with extreme cyclones events (ECE) over Spitzbergen. We have chosen Spitzbergen, representative for the Arctic North Atlantic region which is a hot spot of Arctic climate change showing also significant recent changes in the occurrence of extreme cyclone events.&#160; Complex climate networks have been successfully applied in the analysis of climate teleconnections during the last decade. To analyze time series of unevenly distributed extreme events, event synchronization (ES) networks are appropriate. Using this framework, we analyze the spatial patterns of significant synchronization between extreme cyclone events over the Spitzbergen area and extreme events in sea-level pressure (SLP) in the rest of the Northern hemisphere for the extended winter season from November to March. Based on the SLP fields from the newest atmospheric reanalysis ERA5, we constructed the ES networks over the time period 1979-2019. The spatial features of the complex network topology like Eigenvector centrality, betweenness centrality and network divergence are determined and their general relation to storm tracks, jet streams and waveguides position is discussed. Link bundles in the maps of statistically significant links of ECEs over Spitzbergen with the rest of the Northern Hemisphere have revealed two classes of teleconnections: Class 1 comprises links from various regions of the Northern hemisphere to Spitzbergen, class 2 comprises links from Spitzbergen to various regions of the Northern hemisphere. For each class three specific teleconnections have been determined. By means of composite analysis, the corresponding atmospheric conditions are characterized. As representative of class 1, the teleconnection between extreme events in SLP over the subtropical West Pacific and delayed ECEs at Spitzbergen is investigated. The corresponding lead-lag analysis of atmospheric fields of SLP, geopotential height fields and meridional wind fields suggests that the class 1 teleconnections are caused by tropical forcing of poleward emanating Rossby wave trains. As representative of class 2, the teleconnection between ECEs at Spitzbergen and delayed extreme events in SLP over Northwest Russia is analyzed. The corresponding lead-lag analysis of atmospheric fields of SLP and geopotential height fields from the troposphere to the stratosphere suggests that the class 2 teleconnections are caused by troposphere-stratosphere coupling processes.

Wintertime Extreme Precipitation Events along the Pacific Northwest Coast: Climatology and Synoptic Evolution

Monthly Weather Review ◽

10.1175/mwr-d-11-00197.1 ◽

2012 ◽

Vol 140 (7) ◽

pp. 2021-2043 ◽

Cited By ~ 65

Author(s):

Michael D. Warner ◽

Clifford F. Mass ◽

Eric P. Salathé

Keyword(s):

Pacific Northwest ◽

Extreme Precipitation ◽

Precipitable Water ◽

Small Subset ◽

Climatic Data ◽

Central Pacific ◽

The Pacific ◽

Upper Level ◽

Abstract Extreme precipitation events impact the Pacific Northwest during winter months, causing flooding, landslides, extensive property damage, and loss of life. Outstanding questions about such events include whether there are a range of associated synoptic evolutions, whether such evolutions vary along the coast, and the associated rainfall duration and variability. To answer these questions, this study uses 60 years of National Climatic Data Center (NCDC) daily precipitation observations to identify the top 50 events in two-day precipitation at six coastal stations from northern California to northwest Washington. NCEP–NCAR reanalysis data were used to construct synoptic composite evolutions of these events for each coastal location. Most regional flooding events are associated with precipitation periods of 24 h or less, and two-day precipitation totals identify nearly all major events. Precipitation areas of major events are generally narrow, roughly 200 km in width, and most are associated with atmospheric rivers. Composite evolutions indicate negative anomalies in sea level pressure and upper-level height in the central Pacific, high pressure anomalies over the southwest United States, large positive 850-hPa temperature anomalies along the coast and offshore, and enhanced precipitable water and integrated water vapor fluxes over southwest to northeast swaths. A small subset of extreme precipitation events over the southern portion of the domain is associated with a very different synoptic evolution: a sharp trough in northwesterly flow and post-cold-frontal convection. High precipitable water values are more frequent during the summer, but are not associated with heavy precipitation due to upper-level ridging over the eastern Pacific and weak onshore flow that limit upward vertical velocities.

Projected changes in extreme precipitation events over Iran in the 21st century based on CMIP5 models

Climate Research ◽

10.3354/cr01625 ◽

2020 ◽

Vol 82 ◽

pp. 75-95

Author(s):

M Darand

Keyword(s):

21St Century ◽

Extreme Precipitation ◽

Model Simulation ◽

Climate Extremes ◽

Cmip5 Models ◽

Trend Test ◽

Increased Risk ◽

Projected Changes ◽

Climate extremes have large impacts on human societies and natural ecosystems. Projection of changes in climate extremes is very important for long-term planning. The current study investigated future changes in extreme precipitation events over Iran based on 18 CMIP5 models for the period 2006-2100. National gridded data from the Asfazari database were used to evaluate climate model simulation. Results indicate that models with higher spatial resolution (CCSM4 and MRI-CGCM3) perform better than those with lower resolution in capturing the spatial features of extreme precipitation events. Bias correction was applied to the models and the projected changes were assessed with the nonparametric modified Mann-Kendal trend test and Sen slope estimator at a 95% confidence level. Annual total precipitation (PRPCTOT) and rainy days (RD) were projected to decrease but the intensity and frequency of precipitation extremes were predicted to increase significantly. The projected decreases were larger in northwestern parts than other regions, with PRPCTOT decreasing by 18 to 22 mm decade-1 and RD by 4 to 4.8 d decade-1. Although there were discrepancies in rates between the models, extreme precipitation events over Iran were generally projected to increase. An increase in consecutive dry days (CDD) was predicted for most regions by the end of the 21st century under RCP8.5, with the largest increase of 5 to 6.8 d decade-1 found for northwestern Iran. In eastern areas of Iran, where precipitation occurs extremely rarely, the number of days with daily precipitation exceeding 10 mm (R10) or even 20 mm (R20) were projected to increase significantly. In conclusion, these changes suggest an increased risk of flash floods in Iran from increased extreme precipitation under the RCP8.5 emission scenario.

A global climatological perspective on the importance of Rossby wave breaking and intense moisture transport for extreme precipitation events

10.5194/egusphere-egu21-288 ◽

2021 ◽

Author(s):

Andries Jan De Vries

Keyword(s):

Rossby Wave ◽

Extreme Precipitation ◽

Wave Breaking ◽

Moisture Transport ◽

Synoptic Scale ◽

Rossby Wave Breaking ◽

The World ◽

Upper Level ◽

Extreme precipitation events (EPEs) frequently cause flooding with dramatic socioeconomic impacts in many parts of the world. Previous studies considered two synoptic-scale processes, Rossby wave breaking and intense moisture transport, typically in isolation, and their linkage to such EPEs in several regions. This study presents for the first time a global and systematic climatological analysis of these two synoptic-scale processes, in tandem and in isolation, for the occurrence of EPEs. To this end, we use 40-year ERA-Interim reanalysis data (1979-2018) and apply object-based identification methods for (i) daily EPEs, (ii) stratospheric potential vorticity (PV) streamers as indicators of Rossby wave breaking, and (iii) structures of high vertically integrated horizontal water vapor transport (IVT). First, the importance of these two synoptic-scale processes is demonstrated by case studies of previously documented flood events that inflicted catastrophic impacts in different parts of the world. Next, a climatological quantification shows that Rossby wave breaking is associated with > 90 % of EPEs near high topography and over the Mediterranean, whereas intense moisture transport is linked to > 95 % of EPEs over many coastal zones, consistent with findings of atmospheric river-related studies. Combined Rossby wave breaking and intense moisture transport contributes up to 70 % of EPEs in several subtropical and extratropical regions, including (semi)arid desert regions where tropical-extratropical interactions are of key importance for (heavy) rainfall. A detailed analysis shows that five categories with different combinations of wave breaking and intense moisture transport can reflect a large range of EPE-related weather systems across various climate zones. Odds ratios of EPEs linked to the two synoptic-scale processes suggest that intense moisture transport is stronger associated with the occurrence of EPEs than wave breaking. Furthermore, the relationship between the PV and IVT characteristics and the precipitation volumes shows that the depth of the wave breaking and moisture transport intensity are intimately connected with the extreme precipitation severity. Finally, composites reveal that subtropical and extratropical EPEs, linked to Rossby wave breaking, go along with the formation of upper-level troughs and cyclogenetic processes near the surface downstream, reduced static stability beneath the upper-level forcing (only over water), and dynamical lifting ahead (over water and land). This study concludes with a concept that reconciles well-established meteorological principles with the importance of Rossby wave breaking and intense moisture transport for extreme precipitation events. The findings of this study may contribute to an improved understanding of the atmospheric processes that lead to EPEs, and may find application in climatic studies on extreme precipitation changes in a warming climate.

A global climatological perspective on the importance of Rossby wave breaking and intense moisture transport for extreme precipitation events

10.5194/wcd-2020-44 ◽

2020 ◽

Author(s):

Andries Jan De Vries

Keyword(s):

Rossby Wave ◽

Extreme Precipitation ◽

Wave Breaking ◽

Moisture Transport ◽

Synoptic Scale ◽

Rossby Wave Breaking ◽

Upper Level ◽

High Topography ◽

Abstract. Extreme precipitation events (EPEs) cause frequently flooding with dramatic socioeconomic impacts in many parts of the world. Previous studies considered two synoptic-scale processes, Rossby wave breaking and intense moisture transport, typically in isolation, and their linkage to such EPEs in several regions. This study presents for the first time a global and systematic climatological analysis of these two synoptic-scale processes, in tandem and in isolation, for the occurrence of EPEs. To this end, we use 40-year ERA-Interim reanalysis data (1979–2018) and apply object-based identification methods for (i) daily EPEs, (ii) stratospheric potential vorticity (PV) streamers as indicators of Rossby wave breaking, and (iii) structures of high vertically integrated horizontal water vapor transport (IVT). First, the importance of these two processes is demonstrated by case studies of previously documented flood events that inflicted catastrophic impacts in different parts of the world. Next, a climatological quantification shows that Rossby wave breaking is associated with > 90 % of EPEs near high topography and over the Mediterranean, intense moisture transport is linked to > 90 % of EPEs over many coastal zones, and their combined occurrence contributes to > 70 % of EPEs in several subtropical and extratropical regions. A more detailed analysis shows that a majority of EPEs associated with (1) only Rossby wave breaking are confined to higher-latitude regions that are deprived from remote moisture supplies by high topography and deserts, (2) only intense moisture transport are found circumglobally at the outer tropics, associated with tropical cyclones, tropical easterly waves, and monsoon lows, (3) combined Rossby wave breaking and intense moisture transport dominate a large part of the globe, in particular over dry subtropical regions where tropical-extratropical interactions are of key relevance, (4) remote, far upstream Rossby wave breaking and intense moisture transport occur over mountainous extratropical west coasts, reminiscent of landfalling atmospheric rivers, and (5) neither of the two synoptic-scale processes are concentrated over the inner tropics and high topography at lower latitudes, where EPEs arise under the influence of local forcing. Accordingly, different combinations of wave breaking and intense moisture transport can reflect a large range of weather systems with relevance to EPEs across various climate zones. Furthermore, the relationship between the PV and IVT characteristics and the precipitation volumes shows that the strength of the wave breaking and moisture transport intensity are intimately connected with the extreme precipitation severity. Finally, composites reveal that subtropical and extratropical EPEs, linked to Rossby wave breaking, go along with the formation of upper-level troughs and cyclogenetic processes near the surface downstream, reduced static stability beneath the upper-level forcing (only over water), and dynamical lifting ahead (over water and land). This study concludes with a concept that reconciles well-established meteorological principles with the importance of Rossby wave breaking and intense moisture transport for extreme precipitation events. The findings of this study may contribute to an improved understanding of the atmospheric processes that lead to EPEs, and may find application in climatic studies on extreme precipitation changes in a warming climate.

Extreme Precipitation and Flooding Contribute to Sudden Vegetation Dieback in a Coastal Salt Marsh

Plants ◽

10.3390/plants10091841 ◽

2021 ◽

Vol 10 (9) ◽

pp. 1841

Author(s):

Camille LaFosse Stagg ◽

Michael J. Osland ◽

Jena A. Moon ◽

Laura C. Feher ◽

Claudia Laurenzano ◽

...

Keyword(s):

Salt Marsh ◽

Extreme Precipitation ◽

Large Scale ◽

Coastal Wetland ◽

Global Climate ◽

Elevation Gradient ◽

Climate Extremes ◽

Climate Conditions ◽

Baseline Climate

Climate extremes are becoming more frequent with global climate change and have the potential to cause major ecological regime shifts. Along the northern Gulf of Mexico, a coastal wetland in Texas suffered sudden vegetation dieback following an extreme precipitation and flooding event associated with Hurricane Harvey in 2017. Historical salt marsh dieback events have been linked to climate extremes, such as extreme drought. However, to our knowledge, this is the first example of extreme precipitation and flooding leading to mass mortality of the salt marsh foundation species, Spartina alterniflora. Here, we investigated the relationships between baseline climate conditions, extreme climate conditions, and large-scale plant mortality to provide an indicator of ecosystem vulnerability to extreme precipitation events. We identified plant zonal boundaries along an elevation gradient with plant species tolerant of hypersaline conditions, including succulents and graminoids, at higher elevations, and flood-tolerant species, including S. alterniflora, at lower elevations. We quantified a flooding threshold for wetland collapse under baseline conditions characterized by incremental increases in flooding (i.e., sea level rise). We proposed that the sudden widespread dieback of S. alterniflora following Hurricane Harvey was the result of extreme precipitation and flooding that exceeded this threshold for S. alterniflora survival. Indeed, S. alterniflora dieback occurred at elevations above the wetland collapse threshold, illustrating a heightened vulnerability to flooding that could not be predicted from baseline climate conditions. Moreover, the spatial pattern of vegetation dieback indicated that underlying stressors may have also increased susceptibility to dieback in some S. alterniflora marshes.Collectively, our results highlight a new mechanism of sudden vegetation dieback in S. alterniflora marshes that is triggered by extreme precipitation and flooding. Furthermore, this work emphasizes the importance of considering interactions between multiple abiotic and biotic stressors that can lead to shifts in tolerance thresholds and incorporating climate extremes into climate vulnerability assessments to accurately characterize future climate threats.

The Dominant Role of Extreme Precipitation Events in Antarctic Snowfall Variability

Geophysical Research Letters ◽

10.1029/2018gl081517 ◽

2019 ◽

Vol 46 (6) ◽

pp. 3502-3511 ◽

Cited By ~ 21

Author(s):

John Turner ◽

Tony Phillips ◽

Meloth Thamban ◽

Waliur Rahaman ◽

Gareth J. Marshall ◽

...

Keyword(s):

Extreme Precipitation ◽

Dominant Role ◽

Extreme Precipitation in China in Response to Emission Reductions under the Paris Agreement

Water ◽

10.3390/w11061167 ◽

2019 ◽

Vol 11 (6) ◽

pp. 1167 ◽

Cited By ~ 2

Author(s):

Jintao Zhang ◽

Fang Wang

Keyword(s):

Extreme Precipitation ◽

Climate Extremes ◽

Heavy Precipitation ◽

Paris Agreement ◽

Population Exposure ◽

Emission Reductions ◽

Mitigation And Adaptation ◽

The Future ◽

To avoid more severe impacts from climate change, countries worldwide pledged to implement intended nationally determined contributions (INDCs) for emission reductions (as part of the Paris Agreement). However, it remains unclear what the resulting precipitation change in terms of regional extremes would be in response to the INDC scenarios. Here, we analyzed China’s extreme precipitation response of the next few decades to the updated INDC scenarios within the framework of the Paris Agreement. Our results indicate increases in the intensity and frequency of extreme precipitation (compared with the current level) in most regions in China. The maximum consecutive five-day precipitation over China is projected to increase ~16%, and the number of heavy precipitation days will increase as much as ~20% in some areas. The probability distributions of extreme precipitation events become wider, resulting in the occurrence of more record-breaking heavy precipitation in the future. We further considered the impacts of precipitation-related extremes and found that the projected population exposure to heavy precipitation events will significantly increase in almost all Chinese regions. For example, for heavy precipitation events that exceed the 20 year baseline return value, the population exposure over China increases from 5.7% (5.1–6.0%) to 15.9% (14.2–16.4%) in the INDC-pledge scenario compared with the present-day level. Limiting the warming to lower levels (e.g., 1.5 °C or 2.0 °C) would reduce the population exposure to heavy precipitation, thereby avoiding impacts associated with more intense precipitation events. These results contribute to an improved understanding of the future risk of climate extremes, which is paramount for the design of mitigation and adaptation policies in China.

Mudanças na Estrutura Termodinâmica da Atmosfera na Presença de Vórtices Ciclônicos de Altos Níveis: Um Episódio de Precipitação Extrema no Semiárido Brasileiro (Changes in the Atmospheric Thermodynamic Structure in the Presence of Upper Level...)

Revista Brasileira de Geografia Física ◽

10.26848/rbgf.v5i4.232865 ◽

2012 ◽

Vol 5 (4) ◽

pp. 877

Author(s):

Magaly De Fatima Correia ◽

Weber Andrade Gonçalves ◽

Maria Regina da Silva Aragão ◽

Maryfrance De Cassia S. Diniz

Keyword(s):

Extreme Precipitation ◽

Extreme Rainfall ◽

Thermodynamic Structure ◽

Brazilian Semiarid ◽

Combined Action ◽

Upper Level ◽

The Relationship ◽

A natureza da relação entre a energia potencial convectiva (CAPE), índice de instabilidade K e altas taxas de precipitação sob a influência de vórtices ciclônicos de altos níveis (VCAN) é investigada. Dados de radiossondas realizadas em Petrolina - PE foram utilizados para diagnosticar mudanças na estrutura termodinâmica da atmosfera. Totais diários de precipitação coletados na estação meteorológica de superfície permitiram avaliar a eficiência da utilização dos índices K e CAPE na determinação do grau de instabilidade da atmosfera e previsão de chuvas extremas. A relação entre valores elevados de CAPE e registros de precipitação é evidente no período de estudo. Entretanto, a existência de valores elevados desse índice não implica necessariamente na ocorrência de chuva. As chuvas abundantes e enchentes registradas na região de Petrolina no mês de janeiro de 2004 resultaram da ação conjunta de sistemas atmosféricos de escala local e sinótica. Mecanismos dinâmicos associados com VCAN foram determinantes para liberação ou supressão da atividade convectiva. Palavras - chave: eventos extremos de precipitação, vórtices ciclônicos de altos níveis, convecção, CAPEMAX. Changes in the Atmospheric Thermodynamic Structure in the Presence of Upper Level Cyclonic Vortices: An Episode of Extreme Precipitation in the Brazilian Semiarid ABSTRACT The nature of the relationship between convective potential energy (CAPE), the instability index K and high rainfall rates under the influence of upper level cyclonic vortices is investigated. Upper air sounding data collected in Petrolina – PE, Brazil, were used to diagnose changes in the thermodynamic structure of the atmosphere. Daily precipitation totals observed at the surface meteorological station allowed evaluation of the K and CAPE efficiency in the determination of the degree of atmospheric instability and prediction of extreme rainfall. The relationship between high CAPE values and precipitation is evident in the period of study. However, high CAPE values may not lead to rainfall. The large rainfall totals and flooding registered in the Petrolina region were a result of the combined action of local and synoptic scale atmospheric systems. Dynamical mechanisms associated with VCAN played a major role in the enhancement or inhibition of convective activity.Keywords: extreme precipitation events, upper level cyclonic vortices, convection, CAPEMAX

Hydroclimate Responses over Global Monsoon Regions Following Volcanic Eruptions at Different Latitudes

Journal of Climate ◽

10.1175/jcli-d-18-0707.1 ◽

2019 ◽

Vol 32 (14) ◽

pp. 4367-4385 ◽

Cited By ~ 6

Author(s):

Meng Zuo ◽

Tianjun Zhou ◽

Wenmin Man

Keyword(s):

Extreme Precipitation ◽

Climate Model ◽

Simulation Analysis ◽

Model Simulation ◽

Net Primary Production ◽

Dominant Role ◽

Volcanic Eruptions ◽

Monsoon Circulation ◽

Global Monsoon ◽

Northern Hemispheric

Abstract Understanding the influence of volcanic eruptions on the hydroclimate over global monsoon regions is of great scientific and social importance. However, the link between the latitude of volcanic eruptions and related hydroclimate changes over global monsoon regions in the last millennium remains inconclusive. Here we show divergent hydroclimate responses after different volcanic eruptions based on large sets of reconstructions, observations, and climate model simulation. Both the proxy and observations show that Northern Hemispheric (Southern Hemispheric) monsoon precipitation is weakened by northern (southern) and tropical eruptions but is enhanced by the southern (northern) eruptions. A similar relationship is found in coupled model simulations driven by volcanic forcing. The model evidence indicates that the dynamic processes related to changes in atmospheric circulation play a dominant role in precipitation responses. The dry conditions over the Northern Hemisphere (Southern Hemisphere) and global monsoon regions following northern (southern) and tropical eruptions are induced through weakened monsoon circulation. The wet conditions over Northern Hemispheric (Southern Hemispheric) monsoon regions after southern (northern) eruptions are caused by the enhanced cross-equator flow. We extend our model simulation analysis from mean state precipitation to extreme precipitation and find that the response of the extreme precipitation is consistent with that of the mean precipitation but is more sensitive over monsoon regions. The response of surface runoff and net primary production is stronger than that of precipitation over some submonsoon regions. Our results imply that it is imperative to consider the potential volcanic eruptions at different hemispheres in the design of near-term decadal climate prediction experiments.