scholarly journals Negative entropy flow and its effect on the organization of synoptic-scale severe atmospheric systems

2004 ◽  
Vol 31 (1) ◽  
Author(s):  
Chongjian Liu
Keyword(s):  
Synoptic Scale ◽  
Entropy Flow ◽  
Negative Entropy ◽  
Atmospheric Systems

scholarly journals Implication of Negative Entropy Flow for Local Rainfall

Entropy ◽  
2013 ◽  
Vol 15 (12) ◽  
pp. 3449-3457 ◽  
Author(s):  
Ying Liu ◽  
Chongjian Liu ◽  
Zhaohui Li
Keyword(s):  
Entropy Flow ◽  
Negative Entropy ◽  
Local Rainfall

Mechanism and estimation of negative entropy flow in terrestrial system

2005 ◽  
Vol 15 (2) ◽  
pp. 185-188 ◽  
Author(s):  
Li Shaoxin ◽  
Hua Ben ◽  
Han Guangze ◽  
Wen Dehual
Keyword(s):  
Entropy Flow ◽  
Negative Entropy ◽  
Terrestrial System

scholarly journals Research on Evaluating the Sustainable Operation of Rail Transit System Based on QFD and Fuzzy Clustering

Entropy ◽  
2020 ◽  
Vol 22 (7) ◽  
pp. 750
Author(s):  
Bing Yan ◽  
Liying Yu ◽  
Jing Wang
Keyword(s):  
Fuzzy Clustering ◽  
Weighted Average ◽  
Rail Transit ◽  
Second Phase ◽  
Customer Requirements ◽  
Entropy Flow ◽  
Transit System ◽  
Negative Entropy ◽  
Sustainable Operation ◽  
Method Of Evaluation

The purpose of this study is to evaluate the sustainable operation of rail transit system. In rail transit system, as the most important aspect of negative entropy flow, the effective strategy can offset the increasing entropy of the system and make it have the characteristics of dissipative structure, so as to realize the sustainable operation. At first, this study constructs the Pressure-State-Response (PSR) model to evaluate the sustainable operation of rail transit system. In this PSR model, “pressure” is viewed as customer requirements, which answers the reasons for such changes in rail transit system; “state” refers to the state and environment of system activities, which can be described as the challenges of coping with system pressure; “response” describes the system’s actions to address the challenges posed by customer needs, namely operational strategies. Moreover, then, 13 pressure indices, five state indices and 11 response indices are summarized. In addition, based on quality function deployment (QFD), with 13 pressure indices as input variables, five state indices as customer requirements (CRs) of QFD and 11 response indices as technical attributes (TAs) of QFD, this study proposed the three-phase evaluation method of the sustainable operation of rail transit system to obtain the operational strategy (that is, negative entropy flow): The first phase is to verify that 13 pressure indices can be clustered into five state indices by fuzzy clustering analysis; The second phase is to get the weights of five state indices by evidential reasoning; The third phase is to rate the importance of 11 response indices by integrating fuzzy weighted average and expected value operator. Finally, the proposed model and method of evaluation are applied to the empirical analysis of Shanghai rail transit system. Finally, we come to the conclusion that Shanghai rail transit system should take priority from the following five aspects: “advancement of design standards”, “reliability of subway facilities”, “completeness of operational rules”, “standardization of management operation” and “rationality of passenger flow control”.

scholarly journals Synoptic-scale variability of surface winds and ocean response to atmospheric forcing in the eastern austral Pacific Ocean

Ocean Science ◽  
2019 ◽  
Vol 15 (5) ◽  
pp. 1247-1266 ◽  
Author(s):  
Iván Pérez-Santos ◽  
Romanet Seguel ◽  
Wolfgang Schneider ◽  
Pamela Linford ◽  
David Donoso ◽  
...  
Keyword(s):  
Pacific Ocean ◽  
Southern Hemisphere ◽  
Atmospheric Pressure ◽  
Ekman Transport ◽  
Synoptic Scale ◽  
Wind Variability ◽  
Ocean Atmosphere ◽  
First Time ◽  
High Atmospheric Pressure ◽  
Atmospheric Systems

Abstract. In the Southern Hemisphere, macroscale atmospheric systems such as westerly winds and the southeast Pacific subtropical anti-cyclone (SPSA) influence the wind regime of the eastern austral Pacific Ocean. The average and seasonal behaviors of these systems are well known, although wind variability at different time and distance scales remains largely unexamined. Therefore, the main goal of this study was to determine the variabilities of surface winds on a spatiotemporal scale from 40 to 56∘ S, using QuikSCAT, Advanced Scatterometer (ASCAT), and the fifth major global European Centre for Medium-Range Weather Forecasts (ECMWF) reanalysis (ERA5) surface-wind information complemented with in situ meteorological data. In addition, interactions between the atmospheric systems, together with the ocean–atmosphere response, were evaluated for the period 1999–2018. The empirical orthogonal function detected dominance at the synoptic scale in mode 1, representing approximately 30 % of the total variance. In this mode, low and high atmospheric pressure systems characterized wind variability for a 16.5 d cycle. Initially, mode 2 – which represents approximately 22 % of the variance – was represented by winds from the west/east (43–56∘ S), occurring mostly during spring and summer/fall and winter at an annual timescale (1999–2008) until they were replaced by systems cycling at 27.5 d (2008–2015). This reflects the influence of the baroclinic annular mode in the Southern Hemisphere. Mode 3, representing approximately 15 % of the variance, involved the passage of small-scale low and high atmospheric pressure (LAP and HAP) systems throughout Patagonia. Persistent Ekman suction occurred throughout the year south of the Gulf of Penas and beyond the Pacific mouth of the Strait of Magellan. Easterly Ekman transport (ET) piled these upwelled waters onto the western shore of South America when winds blew southward. These physical mechanisms were essential in bringing nutrients to the surface and then transporting planktonic organisms from the oceanic zone to Patagonian fjords and channels. In the zonal band between 41 and 43∘ S, the latitude of Chiloé Island, upward Ekman pumping and Ekman transport during spring and summer favored a reduced sea surface temperature and increased chlorophyll a (Chl a) levels; this is the first time that such Ekman upwelling conditions have been reported so far south in the eastern Pacific Ocean. The influence of the northward-migrating LAP systems on the ocean–atmosphere interphase allowed us to understand, for the first time, their direct relationship with recorded nighttime air temperature maxima (locally referred to as “nighttime heatwave events”). In the context of global climate change, greater attention should be paid to these processes based on their possible impact on the rate of glacier melting and on the austral climate.

scholarly journals Synoptic scale variability of surface winds and expected changes in the ocean–atmosphere dynamics of the eastern Austral Pacific Ocean

2018 ◽  
Author(s):  
Iván Pérez-Santos ◽  
Romanet Seguel ◽  
Wolfgang Schneider
Keyword(s):  
Pacific Ocean ◽  
Atmospheric Pressure ◽  
Surface Wind ◽  
Synoptic Scale ◽  
Wind Variability ◽  
Westerly Winds ◽  
Ocean Atmosphere ◽  
First Time ◽  
High Atmospheric Pressure ◽  
Atmospheric Systems

Abstract. In the southern hemisphere, macroscale atmospheric systems such as the westerly winds and the Southeast Pacific Subtropical anti-cyclone (SPSA) influence the wind regime of the eastern Austral Pacific Ocean. The average and seasonal behaviors of these systems are well known, although wind variability at different time and distance scales was previously unexamined. The main goal of this study was, therefore, to determine the space and time scale variabilities of surface winds from 40° to 56° S, using QuikSCAT, ASCAT, and ERA-Interim surface wind information, complemented by in situ meteorological data. In addition, interactions between atmospheric systems, together with the ocean–atmosphere dynamics, were evaluated, from 1999 to 2015. The empirical orthogonal function detected dominance at the synoptic scale in mode 1, representing approximately 30 % of the total variance. In this mode, low and high atmospheric pressure systems characterized wind variability, with a cycle length of 16.5 days. Initially, mode 2, representing approximately 22 % of the variance, was represented by westerly winds (43° to 56° S), which occurred mostly during spring and summer, with an annual time scale (1999–2008), until they were replaced by systems cycling at 27.5 days (2008–2015), reflecting the influence of the Southern Hemisphere's baroclinic annular mode. Mode 3, representing approximately 15 % of the variance, involved passage of small scale, low and high atmospheric pressure (LAP, HAP) systems throughout Patagonia. Persistent Ekman suction south of the Gulf of Penas, and up to and beyond the Pacific mouth of the Magellan Strait, occurred throughout the year. Easterly Ekman transport (ET) piled these upwelled waters onto the western shore of South America, when the winds blew southward. These physical mechanisms were essential in bringing nutrients to the surface, and then transporting planktonic organisms from the oceanic zone into Patagonian fjords and channels. In a variation, between 41° and 43° S, surface wind from the SPSA produced offshore ET during spring and summer, causing reduced sea surface temperature, and increased chlorophyll-a; this is the first time that such upwelling conditions have been reported so far south, in the eastern Pacific Ocean. The influence of northward migrating LAP systems on the ocean–atmosphere interphase allowed us to understand, for the first time, their direct relationship with recorded night time air temperature maxima (locally referred to as Nighttime heat wave events). In the context of global climate change, greater attention should be paid to these processes, based on their possible impact on the rate of glacier melting, and on the austral climate.

Sign in / Sign up

Export Citation Format

Share Document