scholarly journals Monsoon Low Pressure System–Like Variability in an Idealized Moist Model

2020 ◽  
Vol 33 (6) ◽  
pp. 2051-2074 ◽  
Author(s):  
Spencer K. Clark ◽  
Yi Ming ◽  
Ángel F. Adames
Keyword(s):  
Potential Vorticity ◽  
General Circulation ◽  
Circulation Model ◽  
Low Pressure ◽  
The Tibetan Plateau ◽  
Pressure System ◽  
Asian Monsoon Region ◽  
Advection Term ◽  
Prior Literature ◽  
Low Pressure System

AbstractIn this paper, it is shown that westward-propagating monsoon low pressure system–like disturbances in the South Asian monsoon region can be simulated in an idealized moist general circulation model through the addition of a simplified parameterization of land. Land is parameterized as having one-tenth the heat capacity of the surrounding slab ocean, with evaporation limited by a bucket hydrology model. In this model, the prominent topography of the Tibetan Plateau does not appear to be necessary for these storm systems to form or propagate; therefore, focus is placed on the simulation with land but no topography. The properties of the simulated storms are elucidated using regression analysis and compared to results from composites of storms from comprehensive GCMs in prior literature and reanalysis. The storms share a similar vertical profile in anomalous Ertel potential vorticity to those in reanalysis. Propagation, however, does not seem to be strongly dictated by beta drift. Rather, it seems to be more closely consistent with linear moisture vortex instability theory, with the exception of the importance of the vertical advection term in the Ertel potential vorticity budget toward the growth and maintenance of disturbances. The results presented here suggest that a simplified GCM configuration might be able to be used to gain a clearer understanding of the sensitivity of monsoon low pressure systems to changes in the mean state climate.

First considerations on the structure and development of the Iberian thermal low-pressure system

1994 ◽  
Vol 12 (5) ◽  
pp. 457-468 ◽  
Author(s):  
S. Alonso ◽  
A. Portela ◽  
C. Ramis
Keyword(s):  
Iberian Peninsula ◽  
Potential Vorticity ◽  
Potential Temperature ◽  
Low Pressure ◽  
Negative Potential ◽  
Absolute Vorticity ◽  
Pressure System ◽  
Friction Forces ◽  
Pressure Disturbance ◽  
Low Pressure System

Abstract. During the summer a thermal low-pressure system is locked over the Iberian Peninsula. We present a first analysis of such a system using the potential vorticity approach. Our results show that its main characteristic is the existence of a negative potential vorticity (PV) dome and a funnel-like structure for potential temperature, both located at the centre of the low. The build-up and evolution of this PV dome can be understood in terms of the dot products of the absolute vorticity and the gradient of diabetic heating vectors and the curl of the friction forces and the gradient of potential temperature vectors. The inhibition of the Algerian Mediterranean cyclogenesis during the summer seems to bear some relation to the existence of this kind of low-pressure disturbance over the Iberian Peninsula.

scholarly journals Numerical Study of a Southwest Vortex Rainstorm Process Influenced by the Eastward Movement of Tibetan Plateau Vortex

2018 ◽  
Vol 2018 ◽  
pp. 1-10
Author(s):  
Xiaoli Liu ◽  
Endian Ma ◽  
Zhibin Cao ◽  
Shuanglong Jin
Keyword(s):  
Tibetan Plateau ◽  
Sichuan Basin ◽  
Low Pressure ◽  
Ice Crystals ◽  
The Tibetan Plateau ◽  
Pressure System ◽  
Convective Clouds ◽  
Low Pressure System ◽  
Southwest Vortex ◽  
The Sichuan Basin

A number of studies revealed the possible eastward movement of the Tibetan Plateau low-pressure system in summer and indicated the enhancement effect of this process on the southwest vortex in the Sichuan Basin, which can induce strong convective precipitation and flood events in China. In this study, a numerical simulation of a southwest vortex rainstorm process was performed. The results show that the low-pressure system originated from the Tibetan Plateau affects the southwest vortex mainly at the middle level, causing the strength increase of southwest vortex (SWV), and acts as a connection between the positive vorticity centers at the upper and lower layers. For the microscopic cloud structure, the vertical updraft of the cloud cluster embedded in the SWV increases as the low-pressure system from the plateau arrives at the Sichuan Basin. Vapor and liquid cloud water at the lower level are transported upward, based on which the ice cloud at the upper level and the warm cloud at the lower level are joined to create favorable conditions for the growth of ice crystals. As the ice crystals grow up, snow and graupel particles form, which substantially elevates the precipitation. This effect leads to the rapid development of SWV rainstorm clouds and the occurrence of precipitation. In addition to the effect of the plateau vortex, the subsequent merging of the convective clouds is another important factor for heavy rainfall because it also leads to development of convective clouds, causing heavy rainfall.

scholarly journals Investigation of the "Elevated Heat Pump" hypothesis of the Asian monsoon using satellite observations

2013 ◽  
Vol 13 (4) ◽  
pp. 10125-10156 ◽  
Author(s):  
M. M. Wonsick ◽  
R. T. Pinker ◽  
Y. Ma
Keyword(s):  
Heat Pump ◽  
Early Onset ◽  
Radiative Forcing ◽  
General Circulation ◽  
Asian Monsoon ◽  
Monsoon Rainfall ◽  
Circulation Model ◽  
Western China ◽  
The Tibetan Plateau ◽  
Asian Monsoon Region

Abstract. In recent years, the "Elevated Heat Pump" (EHP) hypothesis has been a topic of intensive research and controversy. It postulates that aerosol-induced anomalous mid- and upper-tropospheric warming above the Tibetan Plateau leads to an early onset and intensification of Asian monsoon rainfall. The finding is primarily based on results from a NASA Finite-Volume General Circulation Model run with and without radiative forcing from different types of aerosols. In particular, black carbon emissions from sources in Northern India and dust from Western China, Afghanistan, Pakistan, and Southwest Asia affected the modeled anomalous heating. Since the initial discussion of the EHP hypothesis in 2006, the aerosol-monsoon relationship has been addressed using various modeling and observational techniques. The current study takes an observational approach to detect signatures of the "Elevated Heat Pump" effect in the cloud cover and cloud type distributions as derived from Meteosat-5 observations over the Asian Monsoon region, supplemented with temperature data from the NCEP/NCAR Reanalysis and precipitation data from the Global Precipitation Climatology Project (GPCP). Cloud, convection, precipitation, and temperature features for the highest-aerosol years are compared with lower-aerosol content years during the period 2000–2005. Predicted precipitation features in China and Korea are found to be consistent with the hypothesis, but the early onset and intensification of monsoon rainfall over India are not observed. It is proposed that model inaccuracies and/or indirect aerosol effects caused the disagreement between observed and hypothesized behavior.

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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