Momentum budget of low level westerly jet during monsoon onset

MAUSAM ◽  
2022 ◽  
Vol 46 (3) ◽  
pp. 235-244
Author(s):  
P. S. JOSAN
Keyword(s):  
Monsoon Onset ◽  
Diagnostic Study ◽  
Source Terms ◽  
Data Set ◽  
Low Level ◽  
Westerly Jet ◽  
Sink Term ◽  
Momentum Budget ◽  
Westerly Flow ◽  
Budget Equation

In this paper a diagnostic study is carried Out to the source and sink terms for the formation and acceleration/deceleration of low level westerly Jet during monsoon onset. For this purpose momentum budget technique is used. The budget equation is derived in the (x.y.p.t) system. The area is confined to a small box the boundaries over the central Arabian Sea the westerly flow prominent during the onset of monsoon. Each tem in the budget equation is calculated separately. FGG E III b. 1200 UTC data set is used for the analysis. The Coriolis force term is found to be sink term rather than a source tern Tram. Transient north-south term is prominent source terms when time averaged momentum budget is considered. When the time averaged momentum budget for each pressure slab is considered. it is concluded that, north-south force terms are prominent source terms of momentum for all slabs and large .cumulus type convection may contribute  to frictional dissipation of momentum for the upper pressure slabs. Frictional force is the main sink term when one examines the momentum budget for each day and the source term are varying day-by-day. On the average, the jet is accelerated during the period. It is also found that the net momentum tendency is small and oscillatory in nature. it is also found that at Minicoy. rainfall is inversely related to momentum  tendency and whenever westerly jet is strong (weak) the rainfall is less (more). Distribution of U-momentum is also found to be oscillatory ill nature.    

scholarly journals On the Momentum Budget of the Quasi-Biennial Oscillation in the Whole Atmosphere Community Climate Model

2018 ◽  
Vol 76 (1) ◽  
pp. 69-87 ◽  
Author(s):  
Rolando R. Garcia ◽  
Jadwiga H. Richter
Keyword(s):  
Gravity Waves ◽  
Climate Model ◽  
Equatorial Waves ◽  
Quasi Biennial Oscillation ◽  
Community Climate Model ◽  
Westerly Jet ◽  
Momentum Budget ◽  
Zonal Wavenumber ◽  
Biennial Oscillation ◽  
Community Climate

Abstract This study documents the contribution of equatorial waves and mesoscale gravity waves to the momentum budget of the quasi-biennial oscillation (QBO) in a 110-level version of the Whole Atmosphere Community Climate Model. The model has high vertical resolution, 500 m, above the boundary layer and through the lower and middle stratosphere, decreasing gradually to about 1.5 km near the stratopause. Parameterized mesoscale gravity waves and resolved equatorial waves contribute comparable easterly and westerly accelerations near the equator. Westerly acceleration by resolved waves is due mainly to Kelvin waves of zonal wavenumber in the range k = 1–15 and is broadly distributed about the equator. Easterly acceleration near the equator is due mainly to Rossby–gravity (RG) waves with zonal wavenumbers in the range k = 4–12. These RG waves appear to be generated in situ during both the easterly and westerly phases of the QBO, wherever the meridional curvature of the equatorial westerly jet is large enough to produce reversals of the zonal-mean barotropic vorticity gradient, suggesting that they are excited by the instability of the jet. The RG waves produce a characteristic pattern of Eliassen–Palm flux divergence that includes strong easterly acceleration close to the equator and westerly acceleration farther from the equator, suggesting that the role of the RG waves is to redistribute zonal-mean vorticity such as to neutralize the instability of the westerly jet. Insofar as unstable RG waves might be present in the real atmosphere, mixing due to these waves could have important implications for transport in the tropical stratosphere.

The leading mode and factors for coherent variations among the sub-systems of tropical Asian summer monsoon onset

2021 ◽  
pp. 1-63
Keyword(s):  
Summer Monsoon ◽  
Rossby Wave ◽  
Asian Summer Monsoon ◽  
Monsoon Onset ◽  
Positive Phase ◽  
Low Level ◽  
Leading Mode ◽  
Rossby Wave Response ◽  
Asian Summer ◽  
The Mean

Abstract Previous studies on the Asian summer monsoon (ASM) onset mainly focused on each monsoon sub-system. Mainly based on the monthly mean rainfall and low-level winds in May, this study investigated the dominant onset mode from the perspective of the entire tropical ASM region, which reveals the coherent features among the regional-scale onsets. The results of multivariate empirical orthogonal function (MV-EOF) analysis indicate that the MV-EOF1 presents reduced rainfall and anomalous low-level easterly winds at 850 hPa over the tropical ASM region in May during its positive phase. The corresponding principal component (PC1) is highly correlated with the local monsoon onset dates over Arabian Sea, Bay of Bengal, Indo-China Peninsula, and South China Sea, where the mean monsoon onsets occur in May. The only exception is India subcontinent, where the mean monsoon onsets occur in June. The results indicate that the leading mode captures the synchronized variation of monsoon onset over most of Asian monsoon sub-systems, which exhibits remarkably interannual and interdecadal changes. The factors that modulate the coherent variation of the tropical ASM onset are further examined. The simultaneously delayed ASM onset tends to occur during the easterly phase of the 30- to 80-day oscillation, the decaying phase of El Niño, and the positive phase of Pacific Decadal Oscillation (PDO). The 30- to 80-day oscillation serves as a background condition for the synchronized delayed or advanced ASM onset. El Niño-related sea surface temperature anomalies modulate the tropical ASM onset mode by modulating the tropical Walker Circulation and inducing an atmospheric Rossby wave response. The PDO affects the tropical ASM onset mode mainly via the equatorial Rossby wave response and the extratropical Rossby wave train.

Scale sensitivity of the Gill circulation, Part II: Off-equatorial case

2021 ◽  
Author(s):  
Gilles Bellon ◽  
Beatriz Reboredo
Keyword(s):  
Diabatic Heating ◽  
Dynamical Response ◽  
Plane Case ◽  
Horizontal Scale ◽  
Overturning Circulation ◽  
Low Level ◽  
Heating Source ◽  
Horizontal Extent ◽  
Westerly Jet ◽  
Tropospheric Heating

Abstract We investigate the steady dynamical response of the atmosphere on the equatorial β-plane to a steady, localized, mid-tropospheric heating source. Following Part I which investigates the case of an equatorial diabatic heating, we explore the sensitivity of the Gill circulation to the latitudinal location of the heating, together with the sensitivity to its horizontal scale. Again, we focus on characteristics of the response which would be particularly important if the circulation interacted with the hydrologic and energy cycles: overturning circulation and low-level wind. In the off-equatorial case, the intensity of the overturning circulation has the same limit as in the equatorial case for small horizontal extent of the diabatic heating, which is also the limit in the f-plane case. The decrease in this intensity with increasing horizontal scale of the diabatic heating is slightly faster in the off-equatorial case than in the equatorial case, which is due to the increase of rotational winds at the expense of divergent winds. The low-level westerly jet is more intense than in the equatorial case, with larger maximum wind and eastward mass transport that tend to infinity for small horizontal extent of the diabatic heating. In terms of spatial characteristics, this jet has a similar latitudinal extent as in the equatorial case but, unlike in the equatorial case, it extends further equatorward than poleward of the diabatic-heating center. It also extends further eastward than in the equatorial case.

scholarly journals Do wage and wage satisfaction compensate for the effects of a dissatisfying job on life satisfaction?

2019 ◽  
Vol 45 ◽  
Author(s):  
Jacob A. De Coning ◽  
Sebastiaan Rothmann ◽  
Marius W. Stander
Keyword(s):  
Job Satisfaction ◽  
Life Satisfaction ◽  
Well Being ◽  
Ethical Behaviour ◽  
Satisfaction Level ◽  
Wage Level ◽  
Data Set ◽  
Convenience Sample ◽  
Low Level ◽  
High Level

Orientation: Research regarding subjective well-being (including life satisfaction and domain-specific satisfaction) is necessary, given the effects thereof on health, work performance, social relationships and ethical behaviour of employees.Research purpose: This study aimed to investigate the relationships among life satisfaction, job satisfaction and wage satisfaction, as well as how these relationships related to gross wage category in a South African sample.Motivation for the study: While research has shown that wage level and wage satisfaction are positively associated with both job and life satisfaction, the question arises whether wage level and satisfaction would compensate for the negative effect of a dissatisfying job on life satisfaction.Research approach/design and method: A cross-sectional design was used. A non-probability convenience sample (N = 763) in the form of the WageIndicator data set was obtained. Hierarchical log-linear analyses and cross-tabulations were carried out to determine the relationships that existed among the constructs.Main findings: Although job satisfaction and wage satisfaction were strongly related at a low level of wage satisfaction, fewer people were satisfied with their jobs at a high level of wage satisfaction level. Moreover, while job and life satisfaction were strongly related at a low level of job satisfaction level, relatively fewer people were satisfied with their lives at a high level of job satisfaction level. Wage dissatisfaction was associated with dissatisfaction with life but was more strongly associated with life satisfaction at a high level of wage satisfaction. Wage category and wage satisfaction did not interact with the job satisfaction level in affecting life satisfaction.Practical/managerial implications: Managers should attend to the perceptions of wage dissatisfaction at low wage and wage satisfaction levels. Such dissatisfaction may have a negative impact on the job and life satisfaction of employees and result in detrimental effects on employees and organisations.Contribution/value-add: This study contributes to scientific knowledge regarding the relationships between wage, wage satisfaction, job dissatisfaction and life satisfaction.

Who Governs in the Council? Determinants of Ministerial Participation in Council Meetings

2020 ◽  
pp. 088832541990052
Author(s):  
Jan Kovář ◽  
Kamil Kovář
Keyword(s):  
Original Data ◽  
Legislative Elections ◽  
Data Set ◽  
Member States ◽  
Popular Support ◽  
Low Level ◽  
The Government ◽  
Visegrád Countries ◽  
Country Specific ◽  
The Eu

The Council of the EU is the primary institution through which ministers of member states can express their positions on Commission proposals and vote upon legislation. This article first examines the extent to which ministers actually attend Council meetings before moving toward investigating the determinants of ministerial participation in over a period covering almost thirteen years between May 2004 and December 2016. It aims to identify determinants of why ministers from the Visegrad countries participate at some meetings and are absent from others. Using an original data set containing information about 940 Council meetings as well as several country-specific characteristics, we show that, on average, at about four out of every six meetings, ministers are absent. The results of our regressions indicate a pattern in which holding the office of the EU’s rotating presidency, the number of b-points on the agenda, and the size of the government increase the likelihood of ministerial participation in meetings. In contrast, high levels of popular support for Eurosceptic parties and holding of national legislative elections decrease the probability of ministerial attendance. Moreover, meetings of Council formations related to policy areas with a low level of EU competence are significantly less likely to be attended by ministers.

scholarly journals What controls the formation of nocturnal low-level stratus clouds over southern West Africa during the monsoon season?

2019 ◽  
Vol 19 (21) ◽  
pp. 13489-13506 ◽  
Author(s):  
Karmen Babić ◽  
Norbert Kalthoff ◽  
Bianca Adler ◽  
Julian F. Quinting ◽  
Fabienne Lohou ◽  
...  
Keyword(s):  
Boundary Layer ◽  
West Africa ◽  
Climate Models ◽  
Marine Boundary Layer ◽  
Monsoon Season ◽  
Onset Time ◽  
Data Set ◽  
Cold Air ◽  
Low Level ◽  
Stratus Clouds

Abstract. Nocturnal low-level stratus clouds (LLCs) are frequently observed in the atmospheric boundary layer (ABL) over southern West Africa (SWA) during the summer monsoon season. Considering the effect these clouds have on the surface energy and radiation budgets as well as on the diurnal cycle of the ABL, they are undoubtedly important for the regional climate. However, an adequate representation of LLCs in the state-of-the-art weather and climate models is still a challenge, which is largely due to the lack of high-quality observations in this region and gaps in understanding of underlying processes. In several recent studies, a unique and comprehensive data set collected in summer 2016 during the DACCIWA (Dynamics-aerosol-chemistry-cloud interactions in West Africa) ground-based field campaign was used for the first observational analyses of the parameters and physical processes relevant for the LLC formation over SWA. However, occasionally stratus-free nights occur during the monsoon season as well. Using observations and ERA5 reanalysis, we investigate differences in the boundary-layer conditions during 6 stratus-free and 20 stratus nights observed during the DACCIWA campaign. Our results suggest that the interplay between three major mechanisms is crucial for the formation of LLCs during the monsoon season: (i) the onset time and strength of the nocturnal low-level jet (NLLJ), (ii) horizontal cold-air advection, and (iii) background moisture level. Namely, weaker or later onset of NLLJ leads to a reduced contribution from horizontal cold-air advection. This in turn results in weaker cooling, and thus saturation is not reached. Such deviation in the dynamics of the NLLJ is related to the arrival of a cold air mass propagating northwards from the coast, called Gulf of Guinea maritime inflow. Additionally, stratus-free nights occur when the intrusions of dry air masses, originating from, for example, central or south Africa, reduce the background moisture over large parts of SWA. Backward-trajectory analysis suggests that another possible reason for clear nights is descending air, which originated from drier levels above the marine boundary layer.

In situ ground based measurements of low level clouds during 10 years of Pallas cloud experiments.

2020 ◽  
Author(s):  
Konstantinos Doulgeris ◽  
David Brus
Keyword(s):  
Water Content ◽  
Liquid Water ◽  
Meteorological Data ◽  
Liquid Water Content ◽  
Data Set ◽  
Radiative Balance ◽  
Low Level ◽  
Major Factors

<p>Clouds and their interaction with aerosols are considered one of the major factors that are connected with uncertainties in predictions of climate change and are highly associated with earth radiative balance. Semi long term in-situ measurements of Arctic low-level clouds have been conducted during last 10 year (2009 - 2019) autumns at Sammaltunturi station (67◦58´N, 24◦07´E, and 560 m a.s.l.), the part of Pallas Atmosphere - Ecosystem Supersite and Global Atmosphere Watch (GAW) programme. During these years a unique data set of continuous and detailed ground-based cloud observations over the sub-Arctic area was obtained. The in-situ cloud measurements were made using two cloud probes that were installed on the roof of the station: the Cloud, Aerosol and Precipitation Spectrometer probe (CAPS) and the Forward Scattering Spectrometer Probe<strong> (</strong>FSSP<strong>)</strong>, both made by droplet measurement technologies (DMT, Longmont, CO, USA). CAPS in­cludes three instruments: the Cloud Imaging Probe (CIP, 12.5 μm-1.55 mm), the Cloud and Aerosol Spectrometer (CAS-DPOL, 0.51-50 μm) with depolarization feature and the Hotwire Liquid Water Content Sensor (Hotwire LWC, 0 - 3 g/m<sup>3</sup>). Vaisala FD12P weather sensor was used to measure all the meteorological data. The essential cloud microphysical parameters we investigated during this work were the size distributions, the total number concentrations, the effective radius of cloud droplets and the cloud liquid water content. The year to year comparison and correlations among semi long term in situ cloud measurements and meteorology are presented.</p>

scholarly journals Role of the West African Westerly Jet in Sahel Rainfall Variations

2012 ◽  
Vol 25 (8) ◽  
pp. 2880-2896 ◽  
Author(s):  
Bing Pu ◽  
Kerry H. Cook
Keyword(s):  
Decadal Variability ◽  
West African Monsoon ◽  
Moisture Flux ◽  
Relative Vorticity ◽  
West African ◽  
The West ◽  
Low Level ◽  
Westerly Jet ◽  
Positive Vorticity ◽  
Sahel Rainfall

Abstract The West African westerly jet is a low-level feature of the summer climatology that transports moisture from the eastern Atlantic onto the African continent at 8°–11°N. This study examines the relationship between the jet and Sahel precipitation variability in August, when both the jet and rainfall reach their seasonal maxima. Variations of the West African westerly jet are significantly positively correlated with precipitation variations over the Sahel on both interannual and decadal time scales. Three periods are identified (1958–71, 1972–87, and 1988–2009), corresponding to times with a wet Sahel–strong jet, dry Sahel–weak jet, and relatively wet Sahel–strong jet. In wet (dry) periods, enhanced (decreased) westerly moisture fluxes associated with a strong (weak) jet increase (decrease) the low-level moisture content over the Sahel, decreasing (enhancing) the stability of the atmosphere. This association between the jet and Sahel rainfall is also found in case studies of 1964, 1984, 1999, and 2007. The southerly moisture flux associated with the West African monsoon has less pronounced decadal variability than the westerly moisture flux of the West African westerly jet and weaker correlations with Sahel rainfall. When the monsoon flow is weak, for example, 1999 and 2007, the Sahel may still experience positive precipitation anomalies in association with strong westerly moisture transport by the jet. The West African westerly jet is also important for stabilizing the regional vorticity balance by introducing strong relative vorticity gradients. Northward flow advects low relative vorticity south of the jet to balance positive vorticity tendencies generated by midtropospheric condensation.

Bioimpedance Vector Analysis of Elite, Subelite, and Low-Level Male Volleyball Players

2018 ◽  
Vol 13 (9) ◽  
pp. 1250-1253 ◽  
Author(s):  
Francesco Campa ◽  
Stefania Toselli
Keyword(s):  
Body Composition ◽  
Normal Population ◽  
Original Data ◽  
Fat Free Mass ◽  
Vector Analysis ◽  
Data Set ◽  
Bioelectric Impedance ◽  
Low Level ◽  
Elite Group ◽  
Volleyball Players

Purpose: To establish a specific player profile on body-composition parameters and to provide a data set of bioelectric impedances values for male volleyball players. Methods: The study included 201 athletes (age 26.1 [5.4] y, height 191.9 [9.7] cm, weight 86.8 [10.8] kg) registered in the Italian volleyball divisions. The athletes were divided into 3 groups: The elite group comprised 75 players participating in the 1st (Super Lega) division, the subelite group included 65 athletes performing in the 2nd (Serie A2) division, and the low-level group included 61 players participating in the 3rd (Serie B) division. Bioelectric impedance, body weight, and height of the athletes were measured in the second half of the competitive season. In addition, bioelectrical impedance vector analysis was performed. Results: The elite group showed a greater amount of fat-free mass (FFM) and total body water (TBW) and a lower fat mass (FM) than the subelite group (P < .05). In addition, the elite players were taller and heavier and had a higher FFM, FM, TBW, and body cellular mass than the low-level athletes (P < .05). Finally, the mean impedance vectors of the elite group significantly differed from those measured in the normal population and in the other 2 groups (P < .05). Conclusions: This study provides an original data set of body-composition and bioelectric impedance reference values of elite male volleyball players. The results might be useful for interpretation of individual bioimpedance vectors and for defining target regions for volleyball players.

scholarly journals Basal Contamination of Sequencing: Lessons from the GTEx dataset

2019 ◽  
Author(s):  
Tim O. Nieuwenhuis ◽  
Stephanie Yang ◽  
Rohan X. Verma ◽  
Vamsee Pillalamarri ◽  
Dan E. Arking ◽  
...  
Keyword(s):  
Gene Expression ◽  
Tissue Expression ◽  
Rna Seq ◽  
Data Set ◽  
Low Level ◽  
Allelic Differences ◽  
Highly Expressed Genes ◽  
Next Generation Sequencing Ngs ◽  
Cell Data ◽  
Generation Sequencing

AbstractOne of the challenges of next generation sequencing (NGS) is read contamination. We used the Genotype-Tissue Expression (GTEx) project, a large, diverse, and robustly generated dataset, to understand the factors that contribute to contamination. We obtained GTEx datasets and technical metadata and validating RNA-Seq from other studies. Of 48 analyzed tissues in GTEx, 26 had variant co-expression clusters of four known highly expressed and pancreas-enriched genes (PRSS1, PNLIP, CLPS, and/or CELA3A). Fourteen additional highly expressed genes from other tissues also indicated contamination. Sample contamination by non-native genes was associated with a sample being sequenced on the same day as a tissue that natively expressed those genes. This was highly significant for pancreas and esophagus genes (linear model, p=9.5e-237 and p=5e-260 respectively). Nine SNPs in four genes shown to contaminate non-native tissues demonstrated allelic differences between DNA-based genotypes and contaminated sample RNA-based genotypes, validating the contamination. Low-level contamination affected 4,497 (39.6%) samples (defined as 10 PRSS1 TPM). It also led ≥ to eQTL assignments in inappropriate tissues among these 18 genes. We note this type of contamination occurs widely, impacting bulk and single cell data set analysis. In conclusion, highly expressed, tissue-enriched genes basally contaminate GTEx and other datasets impacting analyses. Awareness of this process is necessary to avoid assigning inaccurate importance to low-level gene expression in inappropriate tissues and cells.

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