scholarly journals The Baroclinic Moisture Flux

2016 ◽  
Vol 145 (1) ◽  
pp. 25-47 ◽  
Author(s):  
Ron McTaggart-Cowan ◽  
John R. Gyakum ◽  
Richard W. Moore
Keyword(s):  
Vertical Motion ◽  
Moisture Flux ◽  
Conveyor Belt ◽  
Mean Flow ◽  
Conveyor Belts ◽  
Moist Processes ◽  
The Mean ◽  
Rain Events ◽  
The Many ◽  
Warm Conveyor Belts

Abstract As subsaturated air ascends sloping isentropic surfaces, adiabatic expansion results in cooling and relative moistening. This process is an effective way to precondition the atmosphere for efficient moist processes while bringing parcels to saturation, and thereafter acts to maintain saturation during condensation. The goal of this study is to develop a diagnostic quantity that highlights circulations and regions in which the process of parcel moistening by isentropic ascent is active. Among the many features that rely on this process for the generation of an important fraction of their energy are oceanic cyclones, transitioning tropical cyclones, warm conveyor belts, diabatic Rossby vortices, and predecessor rain events. The baroclinic moisture flux (BMF) is defined as moisture transport by the component of vertical motion associated with isentropic upgliding. In warm conveyor belt and diabatic Rossby vortex case studies, the BMF appears to be successful in identifying the portion of the circulation in which this process is actively bringing parcels to saturation to promote the formation of clouds and precipitation. On a broader scale, the climatological maxima of the BMF highlight regions in which parcel moistening by isentropic ascent is anticipated to have a nonnegligible impact on the atmospheric state either through the action of the mean flow or via the repeated occurrence of isolated large-BMF events. The process-centric foundation of the BMF makes it useful as a filtering or exploratory variable, with the potential for extension into predictive applications.

scholarly journals Effect of anthropogenic aerosol emissions on precipitation in warm conveyor belts in the western North Pacific in winter – a model study with ECHAM6-HAM

2016 ◽  
Author(s):  
Hanna Joos ◽  
Erica Madonna ◽  
Kasja Witlox ◽  
Sylvaine Ferrachat ◽  
Heini Wernli ◽  
...  
Keyword(s):  
North Pacific ◽  
Aerosol Particles ◽  
Conveyor Belt ◽  
Radiation Balance ◽  
Anthropogenic Aerosol ◽  
Model Study ◽  
Conveyor Belts ◽  
Winter Time ◽  
Warm Conveyor Belts ◽  
Aerosol Emissions

Abstract. While there is a clear impact of aerosol particles on the radiation balance, whether and how aerosol particles influence precipitation is controversial. Here we use the ECHAM6-HAM global cli- mate model coupled to an aerosol module to analyse whether an impact of anthropogenic aerosol particles on the timing and the amount of precipitation from warm conveyor belts in low pressure systems in the winter time North Pacific can be detected. We conclude that while polluted warm con- veyor belt trajectories start with 5–10 times higher black carbon concentrations, the overall amount of precipitation is comparable in pre-industrial and present-day conditions. Precipitation formation is however supressed in the most polluted warm conveyor belt trajectories.

scholarly journals Dynamical and Synoptic Characteristics of Heavy Rainfall Episodes in Southern Brazil

2007 ◽  
Vol 135 (2) ◽  
pp. 598-617 ◽  
Author(s):  
Mateusda Silva Teixeira ◽  
Prakki Satyamurty
Keyword(s):  
Heavy Rainfall ◽  
Moisture Flux ◽  
Southern Brazil ◽  
Mean Flow ◽  
Pressure Center ◽  
Average Rainfall ◽  
Meridional Winds ◽  
The Mean ◽  
Low Level Jet ◽  
Atmospheric Variables

Abstract The dynamical and synoptic characteristics that distinguish heavy rainfall episodes from nonheavy rainfall episodes in southern Brazil are discussed. A heavy rainfall episode is defined here as one in which the 50 mm day−1 isohyet encloses an area of not less than 10 000 km2 in the domain of southern Brazil. One hundred and seventy such events are identified in the 11-yr period of 1991–2001. The mean flow patterns in the period of 1–3 days preceding the episodes show some striking synoptic-scale features that may be considered forerunners of these episodes: (i) a deepening midtropospheric trough in the eastern South Pacific approaches the continent 3 days before, (ii) a surface low pressure center forms in northern Argentina 1 day before, (iii) a northerly low-level jet develops over Paraguay 2 days before, and (iv) a strong moisture flux convergence over southern Brazil becomes prominent 1 day before the episode. A parameter called rainfall quantity, defined as the product of the area enclosed by the 50 mm day−1 isohyet and the average rainfall intensity, is correlated with fields of atmospheric variables such as 500-hPa geopotential and 850-hPa meridional winds. Significant lag correlations show that the anomalies of some atmospheric variables could be viewed as precursors of heavy rainfall in southern Brazil that can be explored for use in improving the forecasts.

scholarly journals On the Co-Occurrence of Warm Conveyor Belt Outflows and PV Streamers*

2014 ◽  
Vol 71 (10) ◽  
pp. 3668-3673 ◽  
Author(s):  
Erica Madonna ◽  
Sebastian Limbach ◽  
Christine Aebi ◽  
Hanna Joos ◽  
Heini Wernli ◽  
...  
Keyword(s):  
Life Cycle ◽  
Three Dimensional ◽  
Conveyor Belt ◽  
Rossby Wave Breaking ◽  
Weather Forecasts ◽  
Three Dimensional Objects ◽  
The North ◽  
Conveyor Belts ◽  
Diabatic Processes ◽  
Warm Conveyor Belts

Abstract The co-occurrence of warm conveyor belts (WCBs), strongly ascending moist airstreams in extratropical cyclones, and stratospheric potential vorticity (PV) streamers, indicators for breaking Rossby waves on the tropopause, is investigated for a 21-yr period in the Northern Hemisphere using Interim European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis (ERA-Interim) data. WCB outflows and PV streamers are respectively identified as two- and three-dimensional objects and tracked during their life cycle. PV streamers are more frequent than WCB outflows and nearly 15% of all PV streamers co-occur with WCBs during their life cycle, whereas about 60% of all WCB outflows co-occur with PV streamers. Co-occurrences are most frequent over the North Atlantic and North Pacific in spring and winter. WCB outflows are often located upstream of the PV streamers and form earlier, indicating the importance of diabatic processes for downstream Rossby wave breaking. Less frequently, PV streamers occur first, leading to the formation of new WCBs.

scholarly journals Initial Condition Sensitivity and Predictability of a Severe Extratropical Cyclone Using a Moist Adjoint

2014 ◽  
Vol 142 (1) ◽  
pp. 320-342 ◽  
Author(s):  
James D. Doyle ◽  
Clark Amerault ◽  
Carolyn A. Reynolds ◽  
P. Alex Reinecke
Keyword(s):  
Nonlinear Models ◽  
Conveyor Belt ◽  
Extratropical Cyclone ◽  
Temperature Fields ◽  
Initial Time ◽  
Mean Flow ◽  
Wind Fields ◽  
Moisture Sensitivity ◽  
Low Level ◽  
The Mean

Abstract The sensitivity and predictability of a rapidly developing extratropical cyclone, Xynthia, that had a severe impact on Europe is explored using a high-resolution moist adjoint modeling system. The adjoint diagnostics indicate that the intensity of severe winds associated with the front just prior to landfall was particularly sensitive to perturbations in the moisture and temperature fields and to a lesser degree the wind fields. The sensitivity maxima are found in the low- and midlevels, oriented in a sloped region along the warm front, and maximized within the warm conveyor belt. The moisture sensitivity indicates that only a relatively small filament of moisture within an atmospheric river present at the initial time was critically important for the development of Xynthia. Adjoint-based optimal perturbations introduced into the tangent linear and nonlinear models exhibit rapid growth over 36 h, while initial perturbations of the opposite sign show substantial weakening of the low-level jet and a marked reduction in the spatial extent of the strong low-level winds. The sensitivity fields exhibit an upshear tilt along the sloping warm conveyor belt and front, and the perturbations extract energy from the mean flow as they are untilted by the shear, consistent with the PV unshielding mechanism. The results of this study underscore the need for accurate moisture observations and data assimilation systems that can adequately assimilate these observations in order to reduce the forecast uncertainties for these severe extratropical cyclones. However, given the nature of the sensitivities and the potential for rapid perturbation and error growth, the intrinsic predictability of severe cyclones such as Xynthia is likely limited.

A portrayal of an orographic Warm Conveyor Belt using observations from aircraft, lidar and radar

2020 ◽  
Author(s):  
Maxi Boettcher ◽  
Andreas Schäfler ◽  
Harald Sodemann ◽  
Michael Sprenger ◽  
Stefan Kaufmann ◽  
...  
Keyword(s):  
Western Europe ◽  
Field Experiments ◽  
Marine Boundary Layer ◽  
Conveyor Belt ◽  
Western Mediterranean ◽  
Air Mass ◽  
Conveyor Belts ◽  
The Alps ◽  
The Baltic ◽  
Warm Conveyor Belts

<p>Warm conveyor belts (WCBs) are important airstreams in extratropical<br>cyclones, leading to the formation of intense precipitation<br>and the transport of substantial amounts of water vapour upward and<br>poleward. This study presents a scenario of a WCB that ascended from<br>western Europe towards the Baltic Sea using aircraft, lidar and<br>radar observations from the field experiments HyMeX and<br>T-NAWDEX-Falcon in October 2012.<br>Trajectories based on the ensemble data assimilation<br>system of the ECMWF are used to quantify probabilistically<br>the occurrence of the WCB and Lagrangian matches<br>between different observations. Despite severe limitations<br>for research flights over Europe, the DLR Falcon successfully<br>sampled WCB air masses during different phases of<br>the ascent. The overall picture of the WCB trajectories revealed<br>measurements in several WCB branches: trajectories<br>that ascended from the East Atlantic over northern France<br>while others had their inflow in the western Mediterranean<br>region and passed across the Alps. For the latter ones, Lagrangian<br>matches coincidentally occurred between lidar water<br>vapour measurements in the inflow of the WCB south,<br>radar measurements during the ascent at and its outflow<br>north of the Alps during a mid-tropospheric flight leg over<br>Germany.<br>The comparison of observations and ensemble analyses<br>reveals a moist bias of the analyses in parts of the WCB inflow<br>and an underestimation of cloud water species in the<br>WCB during ascent. In between, the radar instrument measured<br>strongly precipitating WCB air mass with embedded<br>linking trajectories directly above the melting layer while<br>orographically ascending at the southern slops of the Alps.<br>An inert tracer air mass could confirm the long pathway<br>of WCB air from the inflow in the marine boundary layer<br>until the outflow in the upper troposhpere near the Baltic<br>sea several hours later. This case study illustrates the complexity<br>of the interaction of WCBs with the Alpine topography,<br>which leads to (i) various pathways over and around<br>the Alpine crest and (ii) locally steep WCB ascent with increased<br>cloud content that might result in enhancement<br>of precipitation where the WCB flows over the Alps. The<br>combination of observational data and detailed ensemble-based<br>trajectory calculations reveals important aspects of<br>orographically-modified WCBs.</p>

scholarly journals 3-D visualization of ensemble weather forecasts – Part 2: Forecasting warm conveyor belt situations for aircraft-based field campaigns

2015 ◽  
Vol 8 (2) ◽  
pp. 2161-2212 ◽  
Author(s):  
M. Rautenhaus ◽  
C. M. Grams ◽  
A. Schäfler ◽  
R. Westermann
Keyword(s):  
System Integration ◽  
Visual Analysis ◽  
Weather Forecasting ◽  
Conveyor Belt ◽  
Ensemble Prediction ◽  
Wind Fields ◽  
Uncertainty Visualization ◽  
Ensemble Prediction System ◽  
Conveyor Belts ◽  
Warm Conveyor Belts

Abstract. We present the application of interactive 3-D visualization of ensemble weather predictions to forecasting warm conveyor belt situations during aircraft-based atmospheric research campaigns. Motivated by forecast requirements of the T-NAWDEX-Falcon 2012 campaign, a method to predict 3-D probabilities of the spatial occurrence of warm conveyor belts has been developed. Probabilities are derived from Lagrangian particle trajectories computed on the forecast wind fields of the ECMWF ensemble prediction system. Integration of the method into the 3-D ensemble visualization tool Met.3D, introduced in the first part of this study, facilitates interactive visualization of WCB features and derived probabilities in the context of the ECMWF ensemble forecast. We investigate the sensitivity of the method with respect to trajectory seeding and forecast wind field resolution. Furthermore, we propose a visual analysis method to quantitatively analyse the contribution of ensemble members to a probability region and, thus, to assist the forecaster in interpreting the obtained probabilities. A case study, revisiting a forecast case from T-NAWDEX-Falcon, illustrates the practical application of Met.3D and demonstrates the use of 3-D and uncertainty visualization for weather forecasting and for planning flight routes in the medium forecast range (three to seven days before take-off).

scholarly journals Effect of anthropogenic aerosol emissions on precipitation in warm conveyor belts in the western North Pacific in winter – a model study with ECHAM6-HAM

2017 ◽  
Vol 17 (10) ◽  
pp. 6243-6255 ◽  
Author(s):  
Hanna Joos ◽  
Erica Madonna ◽  
Kasja Witlox ◽  
Sylvaine Ferrachat ◽  
Heini Wernli ◽  
...  
Keyword(s):  
North Pacific ◽  
Climate Model ◽  
Global Climate ◽  
Global Climate Model ◽  
Aerosol Particles ◽  
Conveyor Belt ◽  
Radiation Balance ◽  
Anthropogenic Aerosol ◽  
Conveyor Belts ◽  
Warm Conveyor Belts

Abstract. While there is a clear impact of aerosol particles on the radiation balance, whether and how aerosol particles influence precipitation is controversial. Here we use the ECHAM6-HAM global climate model coupled to an aerosol module to analyse whether an impact of anthropogenic aerosol particles on the timing and amount of precipitation can be detected in North Pacific warm conveyor belts. Warm conveyor belts are the strongest precipitation-producing airstreams in extratropical cyclones and are identified here with a Lagrangian technique, i.e. by objectively identifying the most strongly ascending trajectories in North Pacific cyclones. These conveyor belts have been identified separately in 10-year ECHAM6-HAM simulations with present-day and pre-industrial aerosol conditions. Then, the evolution of aerosols and cloud properties has been analysed in detail along the identified warm conveyor belt trajectories. The results show that, under present-day conditions, some warm conveyor belt trajectories are strongly polluted (i.e. high concentrations of black carbon and sulfur dioxide) due to horizontal transport from eastern Asia to the oceanic region where warm conveyor belts start their ascent. In these polluted trajectories a weak delay and reduction of precipitation formation occurs compared to clean warm conveyor belt trajectories. However, all warm conveyor belts consist of both polluted and clean trajectories at the time they start their ascent, and the typically more abundant clean trajectories strongly reduce the aerosol impact from the polluted trajectories. The main conclusion then is that the overall amount of precipitation is comparable in pre-industrial conditions, when all warm conveyor belt trajectories are clean, and in present-day conditions, when warm conveyor belts consist of a mixture of clean and polluted trajectories.

scholarly journals Efficient setup of the belt conveyor speed through of templates

2020 ◽  
Vol 11 (5) ◽  
pp. 1565
Author(s):  
Daniel Corrêa da Silva ◽  
Carlos Eduardo Soares Maia ◽  
Letícia Ali Figueiredo Ferreira ◽  
Ana Carla De Souza Gomes dos Santos ◽  
Genildo Nonato Santos
Keyword(s):  
Graphical Method ◽  
Conveyor Belt ◽  
Theoretical Studies ◽  
Transport Capacity ◽  
Belt Conveyor ◽  
Belt Speed ◽  
Conveyor Belts ◽  
The Many ◽  
The Relationship ◽  
Made In

It is not obvious to adjust the speed of a conveyor belt so that it is possible to optimize the transport for each piece conveyed even with various studies presented in this area. The complex methodologies that are shown and the many adaptations indicated in these studies may contribute to the low adoption of these configurations. A study made, in this work, from videos of advertisements showing belt conveyor in operating on the factory floor which presented only 44% efficiency. In this work, it was shown, through theoretical studies, a mathematical model that presents the relationship between the speed and the transport capacity of conveyor belts. Based on a model, a graphical method (using templates) has been proposed that helps in choosing the conveyor belt speed for most efficient configurations that can be identified and adopted simply and without many adaptations to the system as a whole.

Ratio imaging of intracellular ion concentration

1992 ◽  
Vol 50 (2) ◽  
pp. 1160-1161
Author(s):  
Stephen R. Bolsover
Keyword(s):  
Individual Cell ◽  
Video Camera ◽  
Field Of View ◽  
Ion Concentration ◽  
Fluorescence Signal ◽  
Ion Imaging ◽  
Ratiometric Fluorescence ◽  
Ratio Imaging ◽  
The Mean ◽  
The Many

The field of intracellular ion concentration measurement expanded greatly in the 1980's due primarily to the development by Roger Tsien of ratiometric fluorescence dyes. These dyes have many applications, and in particular they make possible to image ion concentrations: to produce maps of the ion concentration within living cells. Ion imagers comprise a fluorescence microscope, an imaging light detector such as a video camera, and a computer system to process the fluorescence signal and display the map of ion concentration.Ion imaging can be used for two distinct purposes. In the first, the imager looks at a field of cells, measuring the mean ion concentration in each cell of the many in the field of view. One can then, for instance, challenge the cells with an agonist and examine the response of each individual cell. Ion imagers are not necessary for this sort of experiment: one can instead use a system that measures the mean ion concentration in a just one cell at any one time. However, they are very much more convenient.

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