scholarly journals On the relationship between the Madden-Julian Oscillation and 2 m air temperature over central Asia in boreal winter

2016 ◽  
Vol 121 (22) ◽  
pp. 13,250-13,272 ◽  
Author(s):  
Yang Zhou ◽  
Youyu Lu ◽  
Ben Yang ◽  
Jing Jiang ◽  
Anning Huang ◽  
...  
Keyword(s):  
Central Asia ◽  
Air Temperature ◽  
Boreal Winter ◽  
Madden Julian Oscillation ◽  
The Relationship

scholarly journals Effects of the Madden–Julian Oscillation on 2-m air temperature prediction over China during boreal winter in the S2S database

2018 ◽  
Vol 52 (11) ◽  
pp. 6671-6689 ◽  
Author(s):  
Yang Zhou ◽  
Ben Yang ◽  
Haishan Chen ◽  
Yaocun Zhang ◽  
Anning Huang ◽  
...  
Keyword(s):  
Air Temperature ◽  
Boreal Winter ◽  
Madden Julian Oscillation ◽  
Temperature Prediction ◽  
Air Temperature Prediction

The potential predictability of Singapore and Maritime Continent weather regimes in relation to the MJO and ENSO

2020 ◽  
Author(s):  
Muhammad Eeqmal Hassim ◽  
Joshua Lee
Keyword(s):  
Peak Frequency ◽  
Boreal Winter ◽  
Madden Julian Oscillation ◽  
Maritime Continent ◽  
Potential Predictability ◽  
Inter Tropical Convergence Zone ◽  
Weather Regimes ◽  
Seasonal Movement ◽  
Relationship Of ◽  
The Relationship

<p><span>The Madden-Julian Oscillation (MJO) is a well-known source of predictability on sub-seasonal-to-seasonal (S2S) time scales and a major driver of intraseasonal weather variability around the globe. For example, the MJO’s interaction with and influence on daily regional weather in the Maritime Continent-Southeast Asia (MC-SEA) region is thought to be most pronounced during boreal winter (November through February), given that the amplitude of MJO activity is often much stronger during that period compared to other times of the year.</span></p><p><span>In this study, we examine the relationship of the MJO to eight weather regimes (WR) that have been previously defined for Singapore and the MC-SEA region using </span><em><span>k</span></em><span>-means clustering of daily sounding data from reanalysis. These weather regimes cover the whole annual cycle of rainfall with well-defined peak frequency times and mean spatial structures that correspond to the seasonal movement of the Inter-tropical Convergence Zone (ITCZ) across the Equator. Following previous work, we use a statistical method to compute the lagged relationship between each MJO phase and daily WR occurrence between December 1980 - November 2014 to quantify the </span><span>change in the likelihood</span><span> that a certain regime will occur relative to climatology, given an MJO phase in advance. Bimonthly analysis indicates that strong lag relationships exist between MJO phases and certain regimes in different two-month periods, thus giving potential predictability of the type of mean weekly weather in the MC-SEA up to 3-4 weeks ahead. In addition, we consider the modulation of the MJO-WR relationships stratified by the ENSO phase to determine whether the expected WR frequency response to MJO activity varies substantially in different background states.</span></p>

Mechanisms of Arctic Surface Air Temperature Change in Response to the Madden–Julian Oscillation

2012 ◽  
Vol 25 (17) ◽  
pp. 5777-5790 ◽  
Author(s):  
Changhyun Yoo ◽  
Sukyoung Lee ◽  
Steven B. Feldstein
Keyword(s):  
Heat Flux ◽  
Air Temperature ◽  
Phase 1 ◽  
Surface Air Temperature ◽  
The Arctic ◽  
Boreal Winter ◽  
Convective Heating ◽  
Madden Julian Oscillation ◽  
Eddy Heat Flux ◽  
Arctic Surface

Abstract Using lagged composites and projections with the thermodynamic energy equation, in this study the mechanisms that drive the boreal winter Arctic surface air temperature (SAT) change associated with the Madden–Julian oscillation (MJO) are investigated. The Wheeler and Hendon MJO index, which divides the MJO into 8 phases, where phase 1 (phase 5) corresponds to reduced (enhanced) convection over the Maritime Continent and western Pacific Ocean, is used. It is shown that the more zonally localized (uniform) tropical convective heating associated with MJO phase 5 (phase 1) leads to enhanced (reduced) excitation of poleward-propagating Rossby waves, which contribute to Arctic warming (cooling). Adiabatic warming/cooling, eddy heat flux, and the subsequent change in downward infrared radiation (IR) flux are found to be important for the Arctic SAT change. The adiabatic warming/cooling initiates the Arctic SAT change, however, subsequent eddy heat flux makes a greater contribution. The resulting SAT change is further amplified by alteration in downward IR. It is shown that changes in surface sensible and latent heat fluxes oppose the contribution by the above processes.

scholarly journals Mapping the Relationship between Northern Hemisphere Winter Surface Air Temperature and the Madden–Julian Oscillation

2011 ◽  
Vol 139 (8) ◽  
pp. 2439-2454 ◽  
Author(s):  
Yang Zhou ◽  
Keith R. Thompson ◽  
Youyu Lu
Keyword(s):  
North America ◽  
Linear Model ◽  
Air Temperature ◽  
Surface Air Temperature ◽  
Boreal Winter ◽  
Eastern North America ◽  
Madden Julian Oscillation ◽  
State Variables ◽  
Normal Surface ◽  
The Tropics

AbstractA regression-based modeling approach is described for mapping the dependence of atmospheric state variables such as surface air temperature (SAT) on the Madden–Julian oscillation (MJO). For the special case of a linear model the dependence can be described by two maps corresponding to the amplitude and lag of the mean atmospheric response with respect to the MJO. In this sense the method leads to a more parsimonious description than traditional compositing, which usually results in eight maps, one for each MJO phase. Another advantage of the amplitude and phase maps is that they clearly identify propagating signals, and also regions where the response is strongly amplified or attenuated. A straightforward extension of the linear model is proposed to allow the amplitude and phase of the response to vary with the amplitude of the MJO or indices that define the background state of the atmosphere–ocean system. Application of the approach to global SAT for boreal winter clearly shows the propagation of MJO-related signals in both the tropics and extratropics and an enhanced response over eastern North America and Alaska (further enhanced during La Niña years). The SAT response over Alaska and eastern North America is caused mainly by horizontal advection related to variations in shore-normal surface winds that, in turn, can be traced (via signals in the 500-hPa geopotential height) back to MJO-related disturbances in the tropics.

Illicit Economies and Political Violence in Central Asia

2020 ◽  
Author(s):  
Lawrence P. Markowitz ◽  
Mariya Y. Omelicheva
Keyword(s):  
Central Asia ◽  
Political Violence ◽  
Drug Trade ◽  
Weak States ◽  
Collaborative Relationships ◽  
Organized Violence ◽  
Muslim Majority ◽  
Low Levels ◽  
The Relationship ◽  
Terrorist Violence

This chapter examines low levels of terrorist violence in Muslim-majority societies. Studies of terrorism have tended to view the relationship between religion and violence through the narrow lens of security, thereby overpredicting the extent of terrorist violence across societies. After reviewing the various explanations for terrorist violence, and applying them to Central Asia, this chapter explores the conditions under which a state’s involvement in illicit economies—specifically its collusion in the drug trade—can dampen levels of terrorist violence. Combining quantitative analysis (including GIS-enabled tools) with a series of in-depth expert interviews conducted in Central Asia, it emphasizes the complex political economy of security that defines infrastructurally weak states, where political and security apparatuses are often immersed in informal and illicit economies. This approach helps uncover the complex links between religion and organized violence, where state apparatuses are often drawn into collaborative relationships with nonstate actors.

scholarly journals Remote Sensing of Snow Cover Variability and Its Influence on the Runoff of Sápmi’s Rivers

Geosciences ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 130
Author(s):  
Sebastian Rößler ◽  
Marius S. Witt ◽  
Jaakko Ikonen ◽  
Ian A. Brown ◽  
Andreas J. Dietz
Keyword(s):  
Remote Sensing ◽  
Snow Cover ◽  
Air Temperature ◽  
Kendall Test ◽  
The Arctic ◽  
Boreal Winter ◽  
Snowmelt Runoff ◽  
River Catchment ◽  
Catchment Areas ◽  
Runoff Model

The boreal winter 2019/2020 was very irregular in Europe. While there was very little snow in Central Europe, the opposite was the case in northern Fenno-Scandia, particularly in the Arctic. The snow cover was more persistent here and its rapid melting led to flooding in many places. Since the last severe spring floods occurred in the region in 2018, this raises the question of whether more frequent occurrences can be expected in the future. To assess the variability of snowmelt related flooding we used snow cover maps (derived from the DLR’s Global SnowPack MODIS snow product) and freely available data on runoff, precipitation, and air temperature in eight unregulated river catchment areas. A trend analysis (Mann-Kendall test) was carried out to assess the development of the parameters, and the interdependencies of the parameters were examined with a correlation analysis. Finally, a simple snowmelt runoff model was tested for its applicability to this region. We noticed an extraordinary variability in the duration of snow cover. If this extends well into spring, rapid air temperature increases leads to enhanced thawing. According to the last flood years 2005, 2010, 2018, and 2020, we were able to differentiate between four synoptic flood types based on their special hydrometeorological and snow situation and simulate them with the snowmelt runoff model (SRM).

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