scholarly journals Diversity of the Madden-Julian Oscillation

2019 ◽  
Vol 5 (7) ◽  
pp. eaax0220 ◽  
Author(s):  
Bin Wang ◽  
Guosen Chen ◽  
Fei Liu
Keyword(s):  
Climate Modeling ◽  
Intraseasonal Variability ◽  
Dominant Mode ◽  
Extreme Weather Events ◽  
Madden Julian Oscillation ◽  
Kelvin Wave ◽  
Tight Coupling ◽  
Wave Response ◽  
Weather Events ◽  
The Pacific

Madden-Julian Oscillation (MJO) is the dominant mode of atmospheric intraseasonal variability and the cornerstone for subseasonal prediction of extreme weather events. Climate modeling and prediction of MJO remain a big challenge, partially due to lack of understanding the MJO diversity. Here, we delineate observed MJO diversity by cluster analysis of propagation patterns of MJO events, which reveals four archetypes: standing, jumping, slow eastward propagation, and fast eastward propagation. Each type exhibits distinctive east-west asymmetric circulation and thermodynamic structures. Tight coupling between the Kelvin wave response and major convection is unique for the propagating events, while the strength and length of Kelvin wave response distinguish slow and fast propagations. The Pacific sea surface temperature anomalies can affect MJO diversity by modifying the Kelvin wave response and its coupling to MJO convection. The results shed light on the mechanisms responsible for MJO diversity and provide potential precursors for foreseeing MJO propagation.

Diversity of the Madden-Julian Oscillation

2020 ◽  
Author(s):  
Guosen Chen ◽  
Bin Wang ◽  
Fei Liu
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Dominant Mode ◽  
Sea Surface ◽  
Extreme Weather Events ◽  
Madden Julian Oscillation ◽  
Kelvin Wave ◽  
Tight Coupling ◽  
Zonal Scale ◽  
Wave Response

<p>Madden-Julian Oscillation (MJO) is the dominant mode of atmospheric intraseasonal variability and the cornerstone for subseasonal prediction of extreme weather events. Climate modeling and prediction of MJO remain a big challenge, partially due to lack of understanding the MJO diversity. Here, we delineate observed MJO diversity by cluster analysis of propagation patterns of MJO events, which reveals four archetypes: standing, jumping, slow eastward propagation, and fast eastward propagation. Each type of MJO exhibits distinctive east-west asymmetric circulation and thermodynamic structures. Tight coupling between the Kelvin wave response and major convection is unique for the propagating events (slow and fast propagations), while the strength and length of Kelvin wave response distinguish slow and fast propagations. The Pacific sea surface temperature anomalies can affect MJO diversity by modifying the Kelvin wave response and its coupling to MJO convection. An El Niño state tends to increase the zonal scale of Kelvin wave response, to amplify it, and to enhance its coupling to the convection, while a La Niña state tends to decrease the zonal scale of Kelvin wave response, to suppress it, and to weaken its coupling to the major convection. This effect of background sea surface temperature on the MJO diversity has been verified by using a theoretical model. The results shed light on the mechanisms responsible for MJO diversity and provide potential precursors for foreseeing MJO propagation.</p>

Impact of Climate Change on Rural Livelihood: A Case Study of Central Rajasthan

2021 ◽  
Vol 7 (4) ◽  
pp. 19-27
Author(s):  
Saifuddin Soz ◽  
Dhananjay Mankar
Keyword(s):  
Climate Change ◽  
Negative Impact ◽  
Extreme Weather Events ◽  
Household Level ◽  
Impact Of Climate Change ◽  
The People ◽  
Weather Events ◽  
Rural Livelihood ◽  
The Pacific ◽  
The Impact

Climate change is already bringing tremendous influence on people’s lives, particularly the underprivileged. It’s already visible in a variety of ways. In recent decades, Asia and the Pacific have seen consistent warming trends as well as more frequent and powerful extreme weather events such as droughts, cyclones, floods, and hailstorms. This study was done in Ajmer District of Rajasthan, to find out the climate variation in the last 10 years. The study describes the effects due to climate change on the livelihoods of the people, so a descriptive research design was used for the study to find out the impact of climate change on rural livelihood in central Rajasthan. The study is based on a large representative of sample, quantitative data was collected to gain an idea of the impact on the livelihoods due to climate change at the household level. It shows the negative impact of climate change on rural livelihood which forced the people to change their livelihood directly or indirectly. It was found that climate change had an impact on people’s lives and people do understand the variation in climate change in terms of changes in the weather, unseasonal rain, and drought.

Intraseasonal Transitions of the Wintertime Pacific Jet Stream

2020 ◽  
Author(s):  
Maria Madsen ◽  
Jonathan Martin
Keyword(s):  
General Circulation ◽  
Large Scale ◽  
Weather Prediction ◽  
Intraseasonal Variability ◽  
Extreme Weather Events ◽  
Jet Stream ◽  
The Pacific ◽  
Basin Scale ◽  
Jet Variability ◽  
The Impact

<p>The deficiency in predictability at subseasonal-to-seasonal timescales, as compared to prediction at conventional weather prediction timescales, is significant. Intraseasonal variability of atmospheric features like the jet stream, occurring within this gap, lead to extreme weather events that present considerable hazards to society. As jets are an important feature at the interface of the large-scale general circulation and the life cycle of individual weather systems, there is strong incentive to more comprehensively understand their variability.</p><p>The wintertime Pacific jet manifests its intraseasonal variability in two predominant modes: a zonal extension or retraction and a meridional shift by as much as 20° of the jet exit region. These two leading modes are associated with basin-scale anomalies in the Pacific that directly impact weather in Hawaii and continental North America. Although recent work has demonstrated the impact intramodal changes of the Pacific jet have on large-scale structure, sensible weather phenomena, and forecast skill in and around the vast North Pacific Basin, the transitions between the leading modes have hardly been considered and, therefore, are poorly understood. Consequently, this work examines the nature and predictability of transitions between modes of wintertime Pacific jet variability as well as their associated synoptic environments.</p><p>We apply two distinct but complementary statistical analyses to 70 cold seasons (NDJFM 1948/49-2017/18) of daily 250-hPa zonal winds from the NCEP/NCAR Reanalysis to investigate such transitions. Empirical orthogonal analysis (EOF)/principal component (PC) analysis is used to depict the state of the daily Pacific jet as a point in a two dimensional phase space defined by the two leading modes.  Supporting this technique is a self-organizing maps (SOMs) analysis that identifies non-orthogonal, synoptically recurring patterns of the Pacific jet. Together, these analyses show that there are, in fact, preferred transitions between these leading modes of variability. Composite and individual case analyses of preferred transition evolutions provides new insight into the synoptic-scale environments that drive Pacific jet variability.</p>

Prospects for agriculture in 2017

2016 ◽  
Keyword(s):  
Pacific Ocean ◽  
El Nino ◽  
Extreme Weather ◽  
Extreme Weather Events ◽  
Content Type ◽  
Weather Events ◽  
The Pacific ◽  
Weather Phenomenon ◽  
Global Agriculture ◽  
The Pacific Ocean

Subject Prospects for agriculture in 2017. Significance The El Nino weather phenomenon, the heating of the Pacific Ocean, experienced through 2015 and 2016 was one of the strongest recorded, causing extreme weather events and decreasing global agriculture production. Next year promises a departure.

scholarly journals Bamboo Fale: Climate of Change

2021 ◽  
Author(s):  
◽  
Emily Cayford
Keyword(s):  
Climate Change ◽  
Pacific Islands ◽  
Storm Surges ◽  
Extreme Weather Events ◽  
Developed Country ◽  
Sea Levels ◽  
Climate Resilience ◽  
Weather Events ◽  
The Pacific ◽  
The World

<p>The world is currently sitting on the brink of a massive upheaval as Climate Change continues to intensify. At this stage, there is no apparent turning back: the only remaining option is to adapt. While many countries are already feeling the effects, the most vulnerable lie within the Pacific Islands.  With 70% of the Samoan population living along their coastline (The World Bank, 2016), the country is identified as one of the most vulnerable Pacific Islands. It is prone to high waves and storm surges, along with tropical cyclones, which destroy livelihoods and housing, as well as claiming lives.  The traditional architecture of Samoa was originally built to withstand such weather events, but has not been adapting to resist the increased cyclone intensity and rising sea levels. The materials and building practices currently used within Samoa do not have the properties to resist these extreme weather events.  Western building practises have been introduced and into the Samoan construction industry, but has not yet successfully been integrated. Combinations of traditional and Western building practises are, instead, resulting in buildings more vulnerable than ever. This issue remains unresolved, with unsuitable housing remaining one of the largest dilemmas currently faced by Samoa’s inhabitants.  Samoa recently graduated from the classification: Least Developed Country, to be classified as a Developing Country (Pilot Programme for Climate Resilience). This places Samoa as one of the more developed nations of the Pacific, therefore encouraging Samoa to take the lead in resilience to the ever imposing effects of Climate Change. Samoa has a close relationship with both New Zealand and Australia and therefore has access to building expertise, education and materials. Why, then, is Samoa so lacking in architectural resilience to the effects of Climate Change?  This paper endeavours to investigate this gap and, in turn provide a potential resolution. These solutions could aid other Pacific countries as well as encouraging further architectural resilience that can then be mirrored by the remaining, vulnerable countries of the Pacific.  This thesis first investigates the question:  “Why has Samoan culture not developed stronger architectural resilience against Climate Change?”  This thesis then evolves to question:  “How can Samoan architecture be hybridised to influence increased architectural resilience against Climate Change?”</p>

In Situ Climate Modeling for Analyzing Extreme Weather Events

2021 ◽  
Author(s):  
Soumya Dutta ◽  
Natalie Klein ◽  
Li Tang ◽  
Jonathan David Wolfe ◽  
Luke Van Roekel ◽  
...  
Keyword(s):  
Climate Modeling ◽  
Extreme Weather ◽  
Extreme Weather Events ◽  
Weather Events

scholarly journals Variations in the Flow of the Global Atmosphere Associated with a Composite Convectively Coupled Oceanic Kelvin Wave

2010 ◽  
Vol 23 (15) ◽  
pp. 4192-4201 ◽  
Author(s):  
Paul E. Roundy ◽  
Lynn M. Gribble-Verhagen
Keyword(s):  
Southern Oscillation ◽  
Deep Convection ◽  
Composite Analysis ◽  
High Latitudes ◽  
Madden Julian Oscillation ◽  
Global Flow ◽  
Kelvin Wave ◽  
Coupled Mode ◽  
The Pacific ◽  
The Pacific Ocean

Abstract Kelvin waves in the Pacific Ocean occasionally develop and propagate eastward together with anomalies of deep convection and low-level westerly wind. This pattern suggests coupling between the oceanic waves and atmospheric convection. A simple composite analysis based on observed coupled events from October through April demonstrates that this apparent coupled mode is associated with significant large anomalies in the global flow that extend to high latitudes. These high-latitude anomalies are significantly larger than those that are linearly associated with the El Niño–Southern Oscillation (ENSO), and they evolve on time scales between those of the Madden–Julian oscillation and ENSO, potentially providing an opportunity for enhanced subseasonal predictability in the flow of the global atmosphere.

scholarly journals The Madden–Julian Oscillation in CCSM4

2011 ◽  
Vol 24 (24) ◽  
pp. 6261-6282 ◽  
Author(s):  
Aneesh C. Subramanian ◽  
Markus Jochum ◽  
Arthur J. Miller ◽  
Raghu Murtugudde ◽  
Richard B. Neale ◽  
...  
Keyword(s):  
Large Scale ◽  
Intraseasonal Variability ◽  
Power Spectra ◽  
Longwave Radiation ◽  
Meridional Wind ◽  
Dominant Mode ◽  
Madden Julian Oscillation ◽  
Asian Monsoon Region ◽  
Climate System Model ◽  
Zonal Winds

Abstract This study assesses the ability of the Community Climate System Model, version 4 (CCSM4) to represent the Madden–Julian oscillation (MJO), the dominant mode of intraseasonal variability in the tropical atmosphere. The U.S. Climate Variability and Predictability (CLIVAR) MJO Working Group’s prescribed diagnostic tests are used to evaluate the model’s mean state, variance, and wavenumber–frequency characteristics in a 20-yr simulation of the intraseasonal variability in zonal winds at 850 hPa (U850) and 200 hPa (U200), and outgoing longwave radiation (OLR). Unlike its predecessor, CCSM4 reproduces a number of aspects of MJO behavior more realistically. The CCSM4 produces coherent, broadbanded, and energetic patterns in eastward-propagating intraseasonal zonal winds and OLR in the tropical Indian and Pacific Oceans that are generally consistent with MJO characteristics. Strong peaks occur in power spectra and coherence spectra with periods between 20 and 100 days and zonal wavenumbers between 1 and 3. Model MJOs, however, tend to be more broadbanded in frequency than in observations. Broad-scale patterns, as revealed in combined EOFs of U850, U200, and OLR, are remarkably consistent with observations and indicate that large-scale convergence–convection coupling occurs in the simulated MJO. Relations between MJO in the model and its concurrence with other climate states are also explored. MJO activity (defined as the percentage of time the MJO index exceeds 1.5) is enhanced during El Niño events compared to La Niña events, both in the model and observations. MJO activity is increased during periods of anomalously strong negative meridional wind shear in the Asian monsoon region and also during strong negative Indian Ocean zonal mode states, in both the model and observations.

scholarly journals IMPACT OF ARCTIC SEA ICE REDUCTION ON ATMOSPHERIC CIRCULATION PATTERNS

2021 ◽  
Vol 4 (1) ◽  
pp. 103-110
Author(s):  
Viacheslav S. Gradov ◽  
Irina V. Borovko ◽  
Vladimir N. Krupchatnikov
Keyword(s):  
Sea Ice ◽  
Atmospheric Circulation ◽  
Extreme Values ◽  
Arctic Sea Ice ◽  
Storm Tracks ◽  
Extreme Weather Events ◽  
Atmospheric Circulation Patterns ◽  
Weather Events ◽  
The Pacific ◽  
The Impact

This paper focuses on the effect of sea ice melting under the effect of the mechanism of decreasing albedo of dry and wet ice and snow on the structure of atmospheric circulation. In particular, the Impact on storm tracks in the Pacific and Atlantic Oceans is analyzed. Extreme weather events are usually associated with atmospheric blocking conditions. Blocking is such meteorological conditions in which a large anticyclonic atmospheric vortex is observed over an area for several days. The Molteni-Tibaldi blocking criterion and the magnitude of the local anticyclonic wave activity (LAWA) are used to estimate the number of blockings. Extreme values of LAWA may indicate the presence of atmospheric blockings. As a result, there is a weakening and eastward shift of Atlantic storm trajectories. There is almost no influence on the Pacific storm tracks.

Signatures of the Madden-Julian Oscillation in Stratospheric Temperature from Aura MLS

2021 ◽  
Author(s):  
Christoph Hoffmann ◽  
Lena Buth ◽  
Christian von Savigny
Keyword(s):  
Time Scale ◽  
Middle Atmosphere ◽  
Intraseasonal Variability ◽  
Temperature Response ◽  
Madden Julian Oscillation ◽  
Stratospheric Temperature ◽  
The Pacific ◽  
Strong Convection ◽  
Basic Characteristics ◽  
Stratospheric Variability

&lt;p&gt;The Madden-Julian oscillation (MJO) is a major source of intraseasonal variability in the tropical troposphere. It refers to a recurring pattern of strong convection, which travels from the Indian ocean over the Maritime Continent to the Pacific ocean with time scales of 30 to 90 days.&lt;/p&gt;&lt;p&gt;Although some studies have recently indicated that the occurrence of tropospheric MJO events could also affect stratospheric parameters, the MJO is not very much recognized as a source of stratospheric variability. This bears the risk of mixing it up with other sources of variability on this time scale, e.g., with signatures of the solar 27-day variations. Many of the studies that have found MJO signatures in the stratosphere are, however, based on either modelled or reanalyzed data. Particularly, we are not aware of any purely observational studies related to the temperature response in the middle atmosphere.&lt;/p&gt;&lt;p&gt;To fill this gap, we analyze the signature of the MJO in stratospheric temperatures measured by the Microwave Limb Sounder (MLS) satellite instrument aboard the Aura satellite. Analyzing the period from about 2004 to 2018, we indeed identify corresponding temperature variations in various altitudes and locations with many of them being significant according to Monte Carlo tests. The amplitudes of these signatures are on the order of 0.5 K. Moreover, basic characteristics of signatures, which have been identified in the preceding publications, are confirmed in this study based on purely observational data.&lt;/p&gt;&lt;p&gt;Hence, our study supports the coupling of parts of the stratospheric variability on the intraseasonal time scale to anomalous tropospheric convection represented by the MJO.&lt;/p&gt;

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