Rossby wave breaking: climatology, interaction with low-frequency climate variability, and links to extreme weather events

2016 ◽  
pp. 69-78 ◽  
Author(s):  
Olivia Martius ◽  
Gwendal Rivière
Keyword(s):  
Climate Variability ◽  
Rossby Wave ◽  
Wave Breaking ◽  
Low Frequency ◽  
Extreme Weather ◽  
Extreme Weather Events ◽  
Rossby Wave Breaking ◽  
Weather Events

A novel identification and tracking method of weather-relevant 3D Potential vorticity streamers

2021 ◽  
Author(s):  
Christoph Fischer ◽  
Elmar Schömer ◽  
Andreas H. Fink ◽  
Michael Riemer ◽  
Michael Maier-Gerber
Keyword(s):  
Rossby Wave ◽  
Potential Vorticity ◽  
Wave Breaking ◽  
Extreme Weather ◽  
Individual Characteristics ◽  
Distance Functions ◽  
Extreme Weather Events ◽  
Rossby Wave Breaking ◽  
Feature Vectors ◽  
Weather Events

<p>Potential vorticity streamers (PVSs) are elongated quasi-horizontal filaments of stratospheric air in the upper troposphere related to, for example, Rossby wave breaking events. They are known to be related to partly extreme weather events in the midlatitudes and subtropics and can also be involved in (sub-)tropical cyclogenesis. While several algorithms have been developed to identify and track PVSs on planar isentropic surfaces, less is known about the evolution of these streamers in 3D, both climatologically but also for a better understanding of individual weather events. Furthermore, characteristics of their 3D shape have barely been considered as a predictor for high impact weather events like (sub-)tropical cyclones.</p><p>We introduce a novel algorithm for detection and identification of PVSs based on image processing techniques which can be applied to 2D and 3D gridded datasets. The potential vorticity was taken from high resolution isentropic analyses based on the ERA5 dataset. The algorithm uses the 2 PVU (Potential Vorticity Unit) threshold to identify and extract anomalies in the PV field using signed distance functions. This is accomplished by using a stereographic projection to eliminate singularities and keeping track of the reduced distortions by storing precomputed distance maps. This approach is computationally efficient and detects more interesting structures that exhibit the general behavior of PVSs compared to existing 2D techniques.</p><p>For each identified object a feature vector is computed, containing the individual characteristics of the streamers. In the 3D case, the algorithm looks at the structure en bloc instead of operating individually on multiple 2D levels. This also makes the identification stable regarding the seasonal cycle. Feature vectors contain parameters about quality, intensity and shape. In the case of 2D datasets, best-fitting ellipses computed from the statistical moments are regarded as a description of their shape. For 3D datasets, recent visualizations show that the boundary of these structures could be approximated by quadric surfaces . The feature vectors are also amended by tracking information, for example splitting and merging events. This low-dimensional representation serves as base for ERA5 climatologies. The data will be correlated with (sub-)tropical cyclone occurrence to spot useful and novel predictors for cyclone activity and preceding Rossby Wave Breaking events.</p><p>Overall, this new type of PVS identification algorithm, applicable in 2D or 3D, allows to diagnose the role of PVS in extreme weather events, including their predictability in ensemble forecasts.</p>

scholarly journals Extreme Weather Events and Climate Variability Provide a Lens to How Shallow Lakes May Respond to Climate Change

Water ◽  
2016 ◽  
Vol 8 (6) ◽  
pp. 229 ◽  
Author(s):  
Karl Havens ◽  
Hans Paerl ◽  
Edward Phlips ◽  
Mengyuan Zhu ◽  
John Beaver ◽  
...  
Keyword(s):  
Climate Change ◽  
Climate Variability ◽  
Shallow Lakes ◽  
Extreme Weather ◽  
Extreme Weather Events ◽  
Weather Events

scholarly journals Climate change impacts on cattle production: analysis of cattle herders’ climate variability/change adaptation strategies in Nigeria

2019 ◽  
Vol 5 (1) ◽  
pp. 12-23
Author(s):  
Ayansina Ayanlade ◽  
Stephen M. Ojebisi
Keyword(s):  
Climate Change ◽  
Climate Variability ◽  
Extreme Weather ◽  
Adaptation Strategies ◽  
Extreme Weather Events ◽  
Climate Data ◽  
Cattle Production ◽  
Study Region ◽  
Qualitative Approaches ◽  
Weather Events

Abstract The study examines the seasonality in climate and extreme weather events, and its effect on cattle production in the Guinea Savannah ecological zone of Nigeria. The study uses both quantitative and qualitative approaches. Climate data of 34 years were used to examine the trends in rainfall pattern and climate variability while household survey was used to appraise the herders’ awareness of climate variability/change impacts and adaptation strategies. Cumulative Departure Index (CDI) method was used to assess the extreme weather events while descriptive statistics and multinomial logistic (MNL) regression model were used to identify the factors that determined herders’ adaptation strategies to climate change. The results revealed a significant spatiotemporal variation in both rainfall and temperature with CDI ranging from -1.39 to 3.3 and -2.3 to 1.81 respectively. The results revealed a reduction in the amount of water available for cattle production. From survey results, 97.5% of the herders identified drought as the major extreme weather event affecting livestock productivities in the study region. In the herder’s perception, the droughts are more severe in recent years than 34 years ago. The results from MNL revealed that extreme weather events, such as drought, has a positive likelihood on migration, at a 10% level of significance, the events has led to migration of cattle herders from the northern part of the study area toward the southern part in recent years.

scholarly journals Climate Change and Emerging Food Safety Issues

2021 ◽  
Author(s):  
Ramona A. Duchenne-Moutien ◽  
Hudaa Neetoo
Keyword(s):  
Climate Change ◽  
Heavy Metals ◽  
Food Safety ◽  
Climate Variability ◽  
Extreme Weather ◽  
Cold Chain ◽  
Extreme Weather Events ◽  
Global Issues ◽  
Weather Patterns ◽  
Weather Events

Throughout these past decades, climate change has featured among one of the most complex global issues. Characterized by worldwide alterations in weather patterns, along with a concomitant increase in the temperature of the Earth, climate change will undoubtedly have significant effects on food security and food safety. Climate change engenders climate variability, which are significant variations in weather variables and in their frequency. Both climate variability and climate change are thought to threaten the safety of the food supply chain through different pathways. One such pathway is their ability to exacerbate foodborne diseases by influencing the occurrence, persistence, virulence and, in some cases, toxicity of certain groups of disease-causing microorganisms. Food safety can also be compromised by various chemical hazards such as pesticides, mycotoxins and heavy metals. With changes in weather patterns such as lower rainfall, higher air temperature and higher frequency of extreme weather events amongst others, this translates to emerging food safety concerns. These include shortage of safe water for irrigation of agricultural produce, greater use of pesticides due to pest resistance, increased difficulty in achieving a well-controlled cold chain resulting in temperature abuse, or occurrence of flash floods which cause run-off of chemical contaminants in natural water courses. Together, these can result in foodborne infection, intoxication, antimicrobial resistance and long-term bioaccumulation of chemicals and heavy metals in the human body. Furthermore, severe climate variability can result in extreme weather events and natural calamities, which directly or indirectly impair food safety. This review discusses the causes and impacts of climate change and variability on existing as well as emerging food safety risks, and also considers mitigation and adaptation strategies to address the global warming and climate change problem.

scholarly journals A New Perspective toward Cataloging Northern Hemisphere Rossby Wave Breaking on the Dynamic Tropopause

2019 ◽  
Vol 147 (2) ◽  
pp. 409-431 ◽  
Author(s):  
Kevin A. Bowley ◽  
John R. Gyakum ◽  
Eyad H. Atallah
Keyword(s):  
Rossby Wave ◽  
North Pacific ◽  
Wave Breaking ◽  
Potential Temperature ◽  
Low Frequency ◽  
The Arctic ◽  
Rossby Wave Breaking ◽  
Modes Of Variability ◽  
The North ◽  
The North Atlantic Oscillation

Abstract Rossby wave breaking (RWB) events are a common feature on the dynamic tropopause and act to modulate synoptic-scale jet dynamics. These events are characterized on the dynamic tropopause by an irreversible overturning of isentropes and are coupled to troposphere-deep vertical motions and geopotential height anomalies. Prior climatologies have focused on the poleward streamer, the equatorward streamer, or the reversal in potential temperature gradient between the streamers, resulting in differences in the frequencies of RWB. Here, a new approach toward cataloging these events that captures both streamers is applied to the National Centers for Environmental Prediction Reanalysis-2 dataset for 1979–2011. Anticyclonic RWB (AWB) events are found to be nearly twice as frequent as cyclonic RWB (CWB) events. Seasonal decompositions of the annual mean find AWB to be most common in summer (40% occurrence), which is likely due to the Asian monsoon, while CWB is most frequent in winter (22.5%) and is likely due to the equatorward shift in mean baroclinicity. Trends in RWB from 1980 to 2010 illustrate a westward shift in North Pacific AWB during winter and summer (up to 0.4% yr−1), while CWB in the North Pacific increases in winter and spring (up to 0.2% yr−1). These changes are hypothesized to be associated with localized changes in the two-way interaction between the jet and RWB. The interannual variability of AWB and CWB is also explored, and a notable modality to the frequency of RWB is found that may be attributable to known low-frequency modes of variability including the Arctic Oscillation, the North Atlantic Oscillation, and the Pacific–North American pattern.

scholarly journals A New Rossby Wave–Breaking Interpretation of the North Atlantic Oscillation

2008 ◽  
Vol 65 (2) ◽  
pp. 609-626 ◽  
Author(s):  
Tim Woollings ◽  
Brian Hoskins ◽  
Mike Blackburn ◽  
Paul Berrisford
Keyword(s):  
North Atlantic Oscillation ◽  
Rossby Wave ◽  
North Atlantic ◽  
Wave Breaking ◽  
Low Frequency ◽  
Rossby Wave Breaking ◽  
The North ◽  
The North Atlantic ◽  
Hemisphere Winter ◽  
The North Atlantic Oscillation

Abstract This paper proposes the hypothesis that the low-frequency variability of the North Atlantic Oscillation (NAO) arises as a result of variations in the occurrence of upper-level Rossby wave–breaking events over the North Atlantic. These events lead to synoptic situations similar to midlatitude blocking that are referred to as high-latitude blocking episodes. A positive NAO is envisaged as being a description of periods in which these episodes are infrequent and can be considered as a basic, unblocked situation. A negative NAO is a description of periods in which episodes occur frequently. A similar, but weaker, relationship exists between wave breaking over the Pacific and the west Pacific pattern. Evidence is given to support this hypothesis by using a two-dimensional potential-vorticity-based index to identify wave breaking at various latitudes. This is applied to Northern Hemisphere winter data from the 40-yr ECMWF Re-Analysis (ERA-40), and the events identified are then related to the NAO. Certain dynamical precursors are identified that appear to increase the likelihood of wave breaking. These suggest mechanisms by which variability in the tropical Pacific, and in the stratosphere, could affect the NAO.

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