Dynamical analysis of extreme tropopause folding events in the coastal region of Antarctica

2021 ◽  
Author(s):  
Masashi Kohma ◽  
Masatoshi Mizukoshi ◽  
Kaoru Sato
Keyword(s):  
Storm Track ◽  
Coastal Region ◽  
Low Pressure ◽  
Dynamical Analysis ◽  
Pressure System ◽  
Syowa Station ◽  
Low Pressure System ◽  
The Antarctic ◽  
Q Vector ◽  
Tropopause Folding

<p>Rapid and deep descent in the tropopause (the so-called tropopause folding; TF) is often observed in the extratropics. Previous studies pointed out that the frequency of deep TF is maximized along the coast of Antarctica. However, the dynamics of TF in the Antarctic region have not yet been studied adequately. In the present study, the extreme TF in the Antarctic are examined using the state-of-art reanalysis data to clarify the uniqueness of TF in the Antarctic.</p><p>First, the distribution of TF frequency in the extra-tropics of the Southern hemisphere is examined. In austral winter, extreme TF often occurs along the coast of Antarctica. Around Syowa Station (69.0S, 39.6E), the frequency of extreme TF is maximized in August while the frequency is small in austral summer. It is interesting that the coast of Antarctica is located to the south of the maximum of the synoptic-scale eddy kinetic energy. This implies that the maximum of TF frequency along the coast of Antarctica cannot be explained only by the geographical distribution of the storm track.</p><p>Next, to examine the dynamics of the extreme TF events along the coast of Antarctica, we perform composite analyses of the extreme TF events at Syowa Station. When the negative anomaly of tropopause height is maximized, the significant downwelling is observed at the location of the extreme TF. From the analyses using the quasi-geostrophic Q-vector, it is found that the divergence of the Q-vector is observed around Syowa Station. The distribution of Q-vector is explained by the local westerly jet and strengthening of the frontal structure associated with a synoptic low-pressure system extending west-east centered at 70°S over Antarctica. The mechanism of the low-pressure system extending along the coast of Antarctica based on ray-tracing theory under the WKB approximation is also discussed.</p>

scholarly journals IMPACT ASSESSMENT OF TROPICAL CYCLONE HUD HUD ON COASTAL REGION OF VISAKHAPATNAM, ANDHRA PRADESH, INDIA

2015 ◽  
Vol II-2/W2 ◽  
pp. 123-130 ◽  
Author(s):  
G. Vivek ◽  
T. Srinivasa Kumar
Keyword(s):  
Tropical Cyclone ◽  
Coastal Region ◽  
Heavy Rain ◽  
Low Pressure ◽  
Andaman Sea ◽  
Pressure System ◽  
Cyclonic Storm ◽  
Remote Sensing Technique ◽  
Low Pressure System ◽  
Strong Winds

Tropical cyclone is a rapidly rotating storm system characterized by a low pressure center, strong winds, and a spiral arrangements of thunderstorms that produce heavy rain. Tropical cyclones typically form over large bodies of relatively warm water. On 6<sup>th</sup> October 2014 Hud Hud originates from a low pressure system that formed under the influence of an upper air cyclonic circulation in the Andaman Sea. On 9<sup>th</sup> October 2014 the IMD department classified the Hud Hud as a very severe cyclonic storm on IMD scale and category 4 on Staffir-Simpson scale. The cyclone hit the coast of Visakhapatnam on 12<sup>th</sup> October 2014 at wind speed of 175 km/h which caused extensive damage to the city and the neighbouring districts. The damage caused by Cyclone Hud Hud not only changed the landscape of the port city, but also made it the first city in the country to be directly hit by a cyclone since 1891 as per the records of the IMD. The remote sensing technique used here is NDVI. NDVI will separate vegetation and non-vegetation part. The NDVI will be classified in ERDAS and calculated the area using ARCGIS. The satellite data of 4<sup>th</sup> October 2014 show s before the cyclone, 14<sup>th</sup> October 2014 shows after the cyclone and 7<sup>th</sup> December 2014 after two month of cyclone.

scholarly journals Analysis of a Sea Fog Episode at King George Island, Antarctica

Atmosphere ◽  
2019 ◽  
Vol 10 (10) ◽  
pp. 585 ◽  
Author(s):  
Jianqiao Chen ◽  
Bo Han ◽  
Qinghua Yang ◽  
Lixin Wei ◽  
Yindong Zeng ◽  
...  
Keyword(s):  
Surface Wind ◽  
Analysis Data ◽  
Low Pressure ◽  
King George Island ◽  
Pressure System ◽  
Sea Temperature ◽  
Wind Speeds ◽  
Strong Surface ◽  
Low Pressure System ◽  
The Antarctic

In this study, a marine fog episode at King George Island off the Antarctic Peninsula from 26–30 January 2017 was investigated using surface observations, upper-air soundings, and re-analysis data as well as the air mass backward trajectory method. The marine fog episode resulted from an approaching low-pressure system, was maintained at high wind speeds, and quickly dissipated when the low-pressure system passed the observation site. During this episode, cloud lay existed above the fog and stratus, the atmosphere was stably stratified for 1600 m, and the air close to the surface was more mixed than air in the upper layer. The air-sea temperature difference (ASTD) of 1–2 °C and a strong surface wind parallel to the gradient of SST were two important factors in the formation and maintenance of the marine fog near the Antarctic region. The convergence of flux for both water vapor and heat during the fog episode was also discussed.

scholarly journals Snow density along the route traversed by the Japanese-Swedish Antarctic Expedition 2007/08

2012 ◽  
Vol 58 (209) ◽  
pp. 529-539 ◽  
Author(s):  
Shin Sugiyama ◽  
Hiroyuki Enomoto ◽  
Shuji Fujita ◽  
Kotaro Fukui ◽  
Fumio Nakazawa ◽  
...  
Keyword(s):  
Wind Speed ◽  
Surface Wind ◽  
Coastal Region ◽  
Snow Density ◽  
Syowa Station ◽  
Near Surface ◽  
A Value ◽  
Surface Snow ◽  
The Mean ◽  
The Antarctic

AbstractDuring the Japanese-Swedish Antarctic traverse expedition of 2007/08, we measured the surface snow density at 46 locations along the 2800 km long route from Syowa station to Wasa station in East Antarctica. The mean snow density for the upper 1 (or 0.5) m layer varied from 333 to 439 kg m-3 over a region spanning an elevation range of 365-3800 ma.s.l. The density variations were associated with the elevation of the sampling sites; the density decreased as the elevation increased, moving from the coastal region inland. However, the density was relatively insensitive to the change in elevation along the ridge on the Antarctic plateau between Dome F and Kohnen stations. Because surface wind is weak in this region, irrespective of elevation, the wind speed was suggested to play a key role in the near-surface densification. The results of multiple regression performed on the density using meteorological variables were significantly improved by the inclusion of wind speed as a predictor. The regression analysis yielded a linear dependence between the density and the wind speed, with a coefficient of 13.5 kg m-3 (m s-1)-1. This relationship is nearly three times stronger than a value previously computed from a dataset available in Antarctica. Our data indicate that the wind speed is more important to estimates of the surface snow density in Antarctica than has been previously assumed.

Estimation of Design Parameters and Performance for a State-of-the-Art Turbofan

2021 ◽  
Author(s):  
Oliver Sjögren ◽  
Carlos Xisto ◽  
Tomas Grönstedt
Keyword(s):  
Performance Metrics ◽  
State Of The Art ◽  
Low Pressure ◽  
Performance Model ◽  
Cycle Performance ◽  
Civil Aviation ◽  
Design Parameters ◽  
Pressure System ◽  
Public Data ◽  
Low Pressure System

Abstract The aim of this study is to explore the possibility of matching a cycle performance model to public data on a state-of-the-art commercial aircraft engine (GEnx-1B). The study is focused on obtaining valuable information on figure of merits for the technology level of the low-pressure system and associated uncertainties. It is therefore directed more specifically towards the fan and low-pressure turbine efficiencies, the Mach number at the fan-face, the distribution of power between the core and the bypass stream as well as the fan pressure ratio. Available cycle performance data have been extracted from the engine emission databank provided by the International Civil Aviation Organization (ICAO), type certificate datasheets from the European Union Aviation Safety Agency (EASA) and the Federal Aviation Administration (FAA), as well as publicly available data from engine manufacturer. Uncertainties in the available source data are estimated and randomly sampled to generate inputs for a model matching procedure. The results show that fuel performance can be estimated with some degree of confidence. However, the study also indicates that a high degree of uncertainty is expected in the prediction of key low-pressure system performance metrics, when relying solely on publicly available data. This outcome highlights the importance of statistic-based methods as a support tool for the inverse design procedures. It also provides a better understanding on the limitations of conventional thermodynamic matching procedures, and the need to complement with methods that take into account conceptual design, cost and fuel burn.

The effect of vasoactive drugs on the low-pressure system

1978 ◽  
Vol 73 (2) ◽  
pp. 220-229 ◽  
Author(s):  
K. Kirsch ◽  
A. Ameln ◽  
H. J. Wicke
Keyword(s):  
Low Pressure ◽  
Vasoactive Drugs ◽  
Pressure System ◽  
Low Pressure System

scholarly journals Synoptic perspectives on pollutant transport patterns observed by satellites over East Asia: Case studies with a conceptual model

2016 ◽  
Author(s):  
Hyun Cheol Kim ◽  
Soontae Kim ◽  
Seok-Woo Son ◽  
Pius Lee ◽  
Chun-Sil Jin ◽  
...  
Keyword(s):  
High Pressure ◽  
East Asia ◽  
Southern China ◽  
Low Pressure ◽  
Pressure System ◽  
Weather Patterns ◽  
High Pressure System ◽  
Synoptic Weather ◽  
Low Pressure System ◽  
Transport Patterns

Abstract. We demonstrate that daily pollutant transport patterns in East Asia are visible from satellite images when inspected with corresponding synoptic weather analyses. Transport pathways of air pollutants in East Asia are investigated using satellite observations, surface weather charts, and chemical-transport model simulations. It is found that during cool season (fall to spring), pollutant transports in East Asia are largely determined by synoptic weather patterns associated with high pressure system over southern China, which is extended from the Siberia High, and low pressure system over Manchuria, which is initiated by Altai-Sayan cyclogenesis. Based on the relative location and strength of these weather systems, three types of synoptic weather patterns that may contribute to pollutants transport in East Asia, especially in China and Korea, are identified: i.e., (1) a strengthening of the Siberian High and its southeastward propagation; (2) a high-pressure system over southern China followed by a frontal passage associated with a northern low-pressure system; and (3) a stagnant high-pressure system over southern China. For all three patterns, the high-pressure system in southern China is essential for the development of regional air pollution, while frontal activities associated with low-pressure system provide a forcing mechanism to transport those pollutants eastward or southeastward. Observed and simulated surface PM distributions show good agreement in both aerosol optical depth and NO2 column density further implying that anthropogenic emissions also contribute to regional events of high surface PM concentrations. It is argued that the quasi-periodic migration of synoptic weather systems in East Asia works as an efficient pump of pollutants; i.e., regional air pollutions developed under high-pressure systems are transported downstream by low-pressure systems.

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