scholarly journals Charge and discharge of polar cold air mass in northern hemispheric winter

2015 ◽  
Vol 42 (17) ◽  
pp. 7187-7193 ◽  
Author(s):  
Yuki Kanno ◽  
Muhammad Rais Abdillah ◽  
Toshiki Iwasaki
Keyword(s):  
Air Mass ◽  
Cold Air ◽  
Northern Hemispheric

scholarly journals Isentropic Analysis of Polar Cold Airmass Streams in the Northern Hemispheric Winter

2014 ◽  
Vol 71 (6) ◽  
pp. 2230-2243 ◽  
Author(s):  
Toshiki Iwasaki ◽  
Takamichi Shoji ◽  
Yuki Kanno ◽  
Masahiro Sawada ◽  
Masashi Ujiie ◽  
...  
Keyword(s):  
North Atlantic Ocean ◽  
North Pacific Ocean ◽  
Potential Temperature ◽  
Heat Content ◽  
The Arctic ◽  
Eastern Coast ◽  
Mean Flow ◽  
Air Mass ◽  
Cold Air ◽  
Northern Hemispheric

Abstract An analysis method is proposed for polar cold airmass streams from generation to disappearance. It designates a threshold potential temperature θT at around the turning point of the extratropical direct (ETD) meridional circulation from downward to equatorward in the mass-weighted isentropic zonal mean (MIM) and clarifies the geographical distributions of the cold air mass, the negative heat content (NHC), their horizontal fluxes, and their diabatic change rates on the basis of conservation relations of the air mass and thermodynamic energy. In the Northern Hemispheric winter, the polar cold air mass below θT = 280 K has two main streams: the East Asian stream and the North American stream. The former grows over the northern part of the Eurasian continent, flows eastward, turns down southeastward toward East Asia via Siberia, and disappears over the western North Pacific Ocean. The latter grows over the Arctic Ocean, flows toward the eastern coast of North America via Hudson Bay, and disappears over the western North Atlantic Ocean. In their exit regions, wave–mean flow interactions are considered to transfer the angular momentum from the cold airstreams to the upward Eliassen–Palm flux and convert the available potential energy to wave energy.

An air mass-derived cool season climatology of synoptically forced Appalachian cold-air damming

2017 ◽  
Vol 38 (2) ◽  
pp. 530-542 ◽  
Author(s):  
Andrew W. Ellis ◽  
Michael L. Marston ◽  
Daniel A. Nelson
Keyword(s):  
Cool Season ◽  
Air Mass ◽  
Cold Air

Eliminating the major tornado threat in Tornado Alley

2014 ◽  
Vol 28 (22) ◽  
pp. 1450175 ◽  
Author(s):  
R. Tao
Keyword(s):  
Air Flow ◽  
Vertical Axis ◽  
South Texas ◽  
Lower Atmosphere ◽  
Air Mass ◽  
Cold Air ◽  
American Midwest ◽  
The Third ◽  
Tornado Outbreaks ◽  
East West

The 2013 devastating tornadoes in Oklahoma, Illinois and other states in Tornado Alley raise an important question: Can we do something to eliminate the major tornado threats in Tornado Alley? Violent tornadoes in Tornado Alley start from the clash-between northbound warm air flow and southbound cold air flow. As there is no mountain in Tornado Alley ranging from west to east to weaken or block the air flows, some clashes are violent, creating vortex turbulence called supercells. These supercells are initially in horizontal spinning motion at the lower atmosphere and then tilt as the air turns to rise in the storm's updraft, creating a component of spin around a vertical axis. About 30% of supercells develop into tornadoes, causing tremendous damages. Here we show that if we build three east–west great walls in the American Midwest, 300 m high and 50 m wide, one in North Dakota, one passing Oklahoma to east and the third one in the south Texas and Louisiana, we will weaken or block such air mass clashes and therefore diminish the major tornado threat in the Tornado Alley forever. We may also first build such great walls locally at some areas with frequent devastating tornado outbreaks and then gradually extend them.

scholarly journals The role of nocturnal Low-Level-Jet in nocturnal convection and rainfalls in the west Mediterranean coast: the episode of 14 December 2010 in northeast of Iberian Peninsula

2012 ◽  
Vol 8 (1) ◽  
pp. 27-31 ◽  
Author(s):  
J. Mazón ◽  
D. Pino
Keyword(s):  
Iberian Peninsula ◽  
Mesoscale Model ◽  
Return Flow ◽  
Inertial Oscillation ◽  
Air Mass ◽  
Cold Air ◽  
Low Level ◽  
Radar Images ◽  
Synoptic Wind ◽  
Low Level Jet

Abstract. The night of 14 December 2010 radar images of the Spanish Weather Agency recorded a large rain band that moved offshore at the Northeast coast of the Iberian Peninsula. MM5 mesoscale model is used to study the atmospheric dynamics during that day. A Nocturnal Low Level Jet (NLLJ) generated by an inertial oscillation that brings cold air to the coast from inland has been simulated in the area. This cold air interacts with a warmer air mass some kilometers offshore. According to the MM5 mesoscale model simulation, the cold air enhances upward movements of the warm air producing condensation. Additionally, there is a return flow to the coastline at 600–900 m high. This warm air mass interacts again with the cold air moving downslope, also producing condensation inland. The simulation for the night before this episode shows large drainage winds with a NLLJ profile, but no condensation areas. The night after the 14th the simulation also shows drainage winds but without a NLLJ profile. However, an offshore convergence area was produced with a returned flow, but no condensation inland occurred. This fact is in agreement with radar observations which reported no precipitation for these two days. Consequently, NLLJ in combination with a synoptic wind over the sea could enhance condensation and eventually precipitation rates in the Mediterranean Iberian coast.

scholarly journals Return period of cold air mass in Baghdad

2018 ◽  
Vol 3 (2) ◽  
pp. 46 ◽  
Author(s):  
Dalya K. Abass
Keyword(s):  
Return Period ◽  
Binomial Distribution ◽  
Air Mass ◽  
Cold Air ◽  
Air Masses ◽  
Binary Distribution

The occurrence of cold air masses varies in Iraq from cold to very cold at different intervals, where these air masses are concentrated only in winter. In this study, the return period of cold air masses was calculated using a binary distribution (Binomial Distribution), It was found that most cold air masses were likely to return with the same intensity for a period of five years from the study period.

scholarly journals Cold Air Mass Analysis of the Record-Breaking Cold Surge Event over East Asia in January 2016

2019 ◽  
Vol 97 (1) ◽  
pp. 275-293 ◽  
Author(s):  
Junpei YAMAGUCHI ◽  
Yuki KANNO ◽  
Guixing CHEN ◽  
Toshiki IWASAKI
Keyword(s):  
East Asia ◽  
Mass Analysis ◽  
Cold Surge ◽  
Air Mass ◽  
Cold Air

scholarly journals Subseasonal Variations of Wintertime North Pacific Evaporation, Cold Air Surges, and Water Vapor Transport

2017 ◽  
Vol 30 (23) ◽  
pp. 9475-9491 ◽  
Author(s):  
Xuejuan Ren ◽  
Xiu-Qun Yang ◽  
Haibo Hu
Keyword(s):  
Water Vapor ◽  
North Pacific ◽  
Wave Train ◽  
Vapor Transport ◽  
Specific Humidity ◽  
Water Vapor Transport ◽  
Vapor Source ◽  
Air Mass ◽  
Cold Air ◽  
The North

This study addresses subseasonal variations of oceanic evaporation E over the North Pacific during winter and the connection with the cold air surges (CASs) and atmospheric water vapor transport using the OAFlux and ERA-Interim daily data. By performing an empirical orthogonal function (EOF) analysis, two dominant modes of subseasonal evaporation anomaly E′ are identified: a zonal wave train–like pattern (EOF1) and an east negative–west positive dipolar pattern (EOF2) in the midlatitude basin. Further analyses yield the following conclusions. 1) The Siberian high (SH)-related CAS has a crucial role in generation of the EOF1 mode of E′. When the dry and cold air mass passes the region of the warm Kuroshio and its extension [Kuroshio–Oyashio Extension (KOE)], the increased air–sea temperature and moisture differences and intensified wind speed lead to the above-normal oceanic E, and vice versa. 2) The Aleutian low (AL)-related CAS contributes to the EOF2 mode of E′. The intensified AL transports a dramatically colder and drier air mass toward the KOE region and a slightly warmer and wetter one toward the west coast of North America, leading to the east negative–west positive structure of E′ in the midlatitude basin. 3) A quasi-linear relationship exists between E′ and divergent water vapor transport anomalies over the KOE region. Positive (negative) E′ is generally accompanied by anomalous vapor source (sink). 4) The divergent water vapor transport anomalies associated with the two EOFs are preliminarily decided by their individual lower-level wind field anomalies and second by the meridional inhomogeneity of subseasonal specific humidity anomalies. Hydroclimate effects on precipitation over the pan–North Pacific region are also discussed.

scholarly journals Searching for the Elusive Cold-Type Occluded Front

2014 ◽  
Vol 142 (8) ◽  
pp. 2565-2570 ◽  
Author(s):  
David M. Schultz ◽  
Bogdan Antonescu ◽  
Alessandro Chiariello
Keyword(s):  
Temperature Difference ◽  
Cross Sections ◽  
Frontal Zone ◽  
North Atlantic Ocean ◽  
Air Mass ◽  
Cold Air ◽  
Weather Forecasts ◽  
The North ◽  
Medium Range ◽  
Frontal Zones

Abstract According to the Norwegian cyclone model, whether a warm-type or cold-type occluded front forms depends upon which cold air mass is colder: the prewarm-frontal air mass or the postcold-frontal air mass. For example, a cold-type occlusion is said to occur when the occluded front slopes rearward with height because the prewarm-frontal air mass is warmer than the postcold-frontal air mass. This temperature difference and the resulting occluded-frontal structure in the Norwegian cyclone model is part of what is called the temperature rule. Paradoxically, no clear example of a rearward-sloping, cold-type occluded front has been found in the literature, even though the required temperature difference has been documented in several cases. This article presents the first documented, rearward-sloping, cold-type occluded front. This occluded front forms in a cyclone over the North Atlantic Ocean on 3–5 January 2003 and is documented in model output from the European Centre for Medium-Range Weather Forecasts. Cross sections through the evolving cyclone show the occluded front forms as the less statically stable warm-frontal zone ascends over the more stable cold-frontal zone. Such a stability difference between the cold- and warm-frontal zones is consistent with a previously published hypothesis that the less stable air is lifted by the more stable air to form occluded fronts, in disagreement with the temperature rule. Because warm-frontal zones and the cold air underneath tend to be more stable than cold-frontal zones and the postcold-frontal air, warm-type occluded fronts are much more common than cold-type occluded fronts, explaining why well-defined, rearward-sloping, cold-type occluded fronts are not common in the meteorological literature.

Turbulence Measurements in a Young Cyclone Over the Ocean1

1957 ◽  
Vol 38 (1.1) ◽  
pp. 13-16 ◽  
Author(s):  
Andrew F. Bunker
Keyword(s):  
Heat Flow ◽  
Transition Zone ◽  
Thermal Structure ◽  
Air Mass ◽  
Cold Air ◽  
Turbulence Measurements ◽  
Heat Flows ◽  
Low Level ◽  
Strong Turbulence ◽  
Warm Sector

A flight was made through a young coastal storm with a PBY-6A aircraft equipped to measure both mean temperatures and rapid variations of the temperature and turbulent gust velocities. Low level observations were obtained which show the thermal structure of the cyclone and the magnitude of the turbulence, the shearing stresses and the heat flows. Particularly strong turbulence was noted in the transition zone between the cool air of the anticyclone and the faster moving air of the warm sector. Stable air and downward heat flow was observed in the cold air mass.

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