scholarly journals The role of inertial instability in cross-hemispheric coupling

2021 ◽  
Author(s):  
R. S. Lieberman ◽  
J. France ◽  
D. A. Ortland ◽  
S. D. Eckermann
Keyword(s):  
High Latitude ◽  
Equation Model ◽  
Polar Mesospheric Clouds ◽  
Winter Temperatures ◽  
Inertial Instability ◽  
Summer Hemisphere ◽  
Steep Decline ◽  
Strong Amplitude ◽  
Mesospheric Clouds ◽  
First Time

AbstractRecent studies suggest linkages between anomalously warm temperatures in the winter stratosphere, and the high-latitude summer mesopause. The summer temperature anomaly is manifested in the decline of polar mesospheric clouds. The two-day wave is a strong-amplitude and transient summer feature that interacts with the background state so as to warm the high-latitude summer mesopause. This wave has been linked to a low-latitude phenomenon called inertial instability, that is organized by breaking planetary waves in the winter stratosphere. Hence, inertial instability has been identified as a possible nexus between the disturbed winter stratosphere, and summer mesopause warming. We investigate a sustained occurrence of inertial instability during July 19-August 8, 2014. During this period, stratospheric winter temperatures warmed by about 10 K, while a steep decline in polar mesospheric clouds was reported between July 26–August 6. We present, for the first time, wave driving associated with observed inertial instability. The effect of inertial instability is to export eastward momentum from the winter hemisphere across the equator into the summer hemisphere. Using a primitive equation model, we demonstrate that the wave stresses destabilize the stratopause summer easterly jet. The reconfigured wind profile excites the wavenumber 4 component of the two-day wave, leading to enhanced warming of the summer mesopause. This work supports previous numerical investigations that identified planetary wave-driven inertial instability as a source of the two-day wave.

scholarly journals Measurements of global distributions of polar mesospheric clouds during 2005–2012 by MIPAS/Envisat

2016 ◽  
Vol 16 (11) ◽  
pp. 6701-6719 ◽  
Author(s):  
Maya García-Comas ◽  
Manuel López-Puertas ◽  
Bernd Funke ◽  
Á. Aythami Jurado-Navarro ◽  
Angela Gardini ◽  
...  
Keyword(s):  
Michelson Interferometer ◽  
Polar Mesospheric Clouds ◽  
Ice Volume ◽  
Infrared Measurements ◽  
Ice Concentration ◽  
Ice Water Content ◽  
The Difference ◽  
Mesospheric Clouds ◽  
Ice Water ◽  
First Time

Abstract. We have analysed MIPAS (Michelson Interferometer for Passive Atmopheric Sounding) infrared measurements of PMCs for the summer seasons in the Northern (NH) and Southern (SH) hemispheres from 2005 to 2012. Measurements of PMCs using this technique are very useful because they are sensitive to the total ice volume and independent of particle size. For the first time, MIPAS has provided coverage of the PMC total ice volume from midlatitudes to the poles. MIPAS measurements indicate the existence of a continuous layer of mesospheric ice, extending from about  ∼ 81 km up to about 88–89 km on average and from the poles to about 50–60° in each hemisphere, increasing in concentration with proximity to the poles. We have found that the ice concentration is larger in the Northern Hemisphere than in the Southern Hemisphere. The ratio between the ice water content (IWC) in both hemispheres is also latitude-dependent, varying from a NH ∕ SH ratio of 1.4 close to the poles to a factor of 2.1 around 60°. This also implies that PMCs extend to lower latitudes in the NH. A very clear feature of the MIPAS observations is that PMCs tend to be at higher altitudes with increasing distance from the polar region (in both hemispheres), particularly equatorwards of 70°, and that they are about 1 km higher in the SH than in the NH. The difference between the mean altitude of the PMC layer and the mesopause altitude increases towards the poles and is larger in the NH than in the SH. The PMC layers are denser and wider when the frost-point temperature occurs at lower altitudes. The layered water vapour structure caused by sequestration and sublimation of PMCs is present at latitudes northwards of 70° N and more pronounced towards the pole. Finally, MIPAS observations have also shown a clear impact of the migrating diurnal tide on the diurnal variation of the PMC volume ice density.

scholarly journals Measurements of Global Distributions of Polar Mesospheric Clouds during 2005–2012 by MIPAS/Envisat

2016 ◽  
Author(s):  
Maya García-Comas ◽  
Manuel López-Puertas ◽  
Bernd Funke ◽  
Á. Aythami Jurado-Navarro ◽  
Angela Gardini ◽  
...  
Keyword(s):  
Polar Mesospheric Clouds ◽  
Ice Volume ◽  
Ice Concentration ◽  
Ice Water Content ◽  
The Mean ◽  
The Difference ◽  
Mesospheric Clouds ◽  
Ice Water ◽  
First Time ◽  
Northern And Southern Hemispheres

Abstract. We have analysed the MIPAS IR measurements of PMCs for the summer seasons in the Northern and Southern Hemispheres from 2005 to 2012. Measurements of PMCs using this technique are very useful because they are sensitive to the total ice volume independent of particle size. For the first time, MIPAS has provided coverage of the PMCs total ice volume from mid-latitudes to the poles. MIPAS measurements indicate the existence of a continuous layer of mesospheric ice, extending from about ~ 81 km up to about 88–89 km on average and from the poles to about 50–60º in each hemisphere, increasing in concentration with proximity to the poles. We have found that the ice concentration is larger in the Northern Hemisphere than in the Southern Hemisphere. The ratio between the ice water content (IWC) in both hemispheres is also latitude-dependent, varying from a NH / SH ratio of 1.4 close to the poles to a factor of 2.1 around 60º. This also implies that PMCs extend to lower latitudes in the NH. A very clear feature of the MIPAS observations is that PMCs tend to be at higher altitudes with increasing distance from the polar region (in both hemispheres), particularly equator-wards of 70º, and that they are about 1 km higher in the SH than in the NH. The difference between the mean altitude of the PMC layer and the mesopause altitude increases towards the poles and is larger in the NH than in the SH. The PMC layers are denser and wider when the frost point temperature occurs at lower altitudes. The layered water vapour structure caused by sequestration and by sublimation of PMCs is more pronounced at latitudes northernmost of 70 degrees. Finally, MIPAS observations have also shown a clear impact of the migrating diurnal tide on the diurnal variation of the PMCs ice concentration.

scholarly journals The relationship between polar mesospheric clouds and their background atmosphere as observed by Odin-SMR and Odin-OSIRIS

2016 ◽  
Vol 16 (19) ◽  
pp. 12587-12600 ◽  
Author(s):  
Ole Martin Christensen ◽  
Susanne Benze ◽  
Patrick Eriksson ◽  
Jörg Gumbel ◽  
Linda Megner ◽  
...  
Keyword(s):  
Growth Model ◽  
Thermodynamic Equilibrium ◽  
Mass Density ◽  
Particle Growth ◽  
Polar Mesospheric Clouds ◽  
Vertical Variations ◽  
High Bias ◽  
Mesospheric Clouds ◽  
Ice Content ◽  
First Time

Abstract. In this study the properties of polar mesospheric clouds (PMCs) and the background atmosphere in which they exist are studied using measurements from two instruments, OSIRIS and SMR, on board the Odin satellite. The data comes from a set of tomographic measurements conducted by the satellite during 2010 and 2011. The expected ice mass density and cloud frequency for conditions of thermodynamic equilibrium, calculated using the temperature and water vapour as measured by SMR, are compared to the ice mass density and cloud frequency as measured by OSIRIS. We find that assuming thermodynamic equilibrium reproduces the seasonal, latitudinal and vertical variations in ice mass density and cloud frequency, but with a high bias of a factor of 2 in ice mass density. To investigate this bias, we use a simple ice particle growth model to estimate the time it would take for the observed clouds to sublimate completely and the time it takes for these clouds to reform. We find a difference in the median sublimation time (1.8 h) and the reformation time (3.2 h) at peak cloud altitudes (82–84 km). This difference implies that temperature variations on these timescales have a tendency to reduce the ice content of the clouds, possibly explaining the high bias of the equilibrium model. Finally, we detect and are, for the first time, able to positively identify cloud features with horizontal scales of 100 to 300 km extending far below the region of supersaturation ( > 2 km). Using the growth model, we conclude these features cannot be explained by sedimentation alone and suggest that these events may be an indication of strong vertical transport.

scholarly journals The relationship between Polar Mesospheric Clouds and their background atmosphere as observed by Odin-SMR and Odin-OSIRIS

2016 ◽  
Author(s):  
Ole Martin Christensen ◽  
Susanne Benze ◽  
Patrick Eriksson ◽  
Jörg Gumbel ◽  
Linda Megner ◽  
...  
Keyword(s):  
Growth Model ◽  
Thermodynamic Equilibrium ◽  
Mass Density ◽  
Particle Growth ◽  
Polar Mesospheric Clouds ◽  
Vertical Variations ◽  
High Bias ◽  
Mesospheric Clouds ◽  
Ice Content ◽  
First Time

Abstract. In this study the properties of Polar Mesospheric Clouds (PMCs) and the background atmosphere in which they exist are studied using measurements from two instruments, OSIRIS and SMR, on-board the Odin satellite. The data comes from a set of tomographic measurements conducted by the satellite during 2010 and 2011. The expected ice mass density and cloud frequency for conditions of thermodynamic equilibrium, calculated using the temperature and water vapour as measured by SMR, are compared to the ice mass density and cloud frequency as measured by OSIRIS. Similar to previous studies, we find that assuming thermodynamic equilibrium reproduces the seasonal, latitudinal and vertical variations in ice mass density and cloud frequency, but with a high bias of a factor of 2 in ice mass density. To explain this bias we use a simple ice particle growth model to estimate the time it would take for the observed clouds to sublimate completely and the time it takes for these clouds to reform. We find a difference in the median sublimation time (2.1 h) and the reformation time (3.2 h) at peak cloud altitudes (82–84 km). This difference implies that temperature variations on these timescales have a tendency to reduce the ice content of the clouds, explaining the high bias of the equilibrium model. Finally, we detect, and are for the first time able to positively identify, cloud features with horizontal scales of 100 to 300 km extending far below the region of supersaturation (> 2 km). Using the growth model, we conclude these features cannot be explained by sedimentation alone, and suggest that these events may be indication of strong vertical transport.

scholarly journals Leymann Inventory of Psychological Terror Scale: Development and Validation for Portuguese Accounting Professionals

Economies ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 94
Author(s):  
Rui Silva ◽  
Margarida Simões ◽  
Ana Paula Monteiro ◽  
António Dias
Keyword(s):  
Structural Equation ◽  
Equation Model ◽  
Quantitative Methodology ◽  
Scale Development And Validation ◽  
Statistical Reliability ◽  
Accounting Professionals ◽  
Final Sample ◽  
Development And Validation ◽  
First Time ◽  
Descriptive Statistical Analysis

This research aims to adapt the Leymann Inventory of Psychological Terror and its use on Portuguese Accounting Professionals. Leymann scale was applied in a final sample of 478 accountants aged between 28 and 68, of which 47.5% were men and 52.5% women. We used a quantitative methodology by applying a questionnaire survey whose results were, in the following research phase, analyzed using the statistical packages SPSS 26 and AMOS 27. We used SPSS 26 for the Descriptive Statistical Analysis and AMOS 27 to estimate the structural equation model that validated the scale. After the scale had been adapted and changed, it was validated in psychometric terms to be applied to and used in studies involving this type of professionals. The Accountants Leymann Inventory of Psychological Terror that resulted from adapting the original model was tested using structural equation modelling. Thus, the new scale produced significant results similar to those of the original scale, which means that it is valid and can be applied to other contexts. The validity and statistical reliability of the new scale made it possible to measure mobbing problems among accounting professionals reliably and robustly. The present research is an important contribution to the literature. Although it has been applied in several contexts, it is the first time it is being developed, adapted, and validated for accounting professionals who work in this area of management.

Middle ultraviolet imager observations of the distribution of polar mesospheric clouds

2001 ◽  
Vol 27 (10) ◽  
pp. 1703-1708 ◽  
Author(s):  
J.F. Carbary ◽  
D. Morrison ◽  
G.J. Romick ◽  
L.J. Paxton ◽  
C.-I. Meng
Keyword(s):  
Polar Mesospheric Clouds ◽  
Mesospheric Clouds

scholarly journals A new Description of Probability Density Distributions of Polar Mesospheric Clouds (PMC)

2018 ◽  
Author(s):  
Uwe Berger ◽  
Gerd Baumgarten ◽  
Jens Fiedler ◽  
Franz-Josef Lübken
Keyword(s):  
Probability Density ◽  
Mass Density ◽  
Particle Radius ◽  
Number Density ◽  
Data Set ◽  
Statistical Probability ◽  
Polar Mesospheric Clouds ◽  
Density Distributions ◽  
Mesospheric Clouds ◽  
Probability Density Distributions

Abstract. In this paper we present a new description about statistical probability density distributions (pdfs) of Polar Mesospheric Clouds (PMC) and noctilucent clouds (NLC). The analysis is based on observations of maximum backscatter, ice mass density, ice particle radius, and number density of ice particles measured by the ALOMAR RMR-lidar for all NLC seasons from 2002 to 2016. From this data set we derive a new class of pdfs that describe the statistics of PMC/NLC events which is different from previously statistical methods using the approach of an exponential distribution commonly named g-distribution. The new analysis describes successfully the probability statistic of ALOMAR lidar data. It turns out that the former g-function description is a special case of our new approach. In general the new statistical function can be applied to many kinds of different PMC parameters, e.g. maximum backscatter, integrated backscatter, ice mass density, ice water content, ice particle radius, ice particle number density or albedo measured by satellites. As a main advantage the new method allows to connect different observational PMC distributions of lidar, and satellite data, and also to compare with distributions from ice model studies. In particular, the statistical distributions of different ice parameters can be compared with each other on the basis of a common assessment that facilitate, for example, trend analysis of PMC/NLC.

Climatology of Polar Mesospheric Clouds

1986 ◽  
Vol 43 (12) ◽  
pp. 1263-1274 ◽  
Author(s):  
John J. Olivero ◽  
Gary E. Thomas
Keyword(s):  
Polar Mesospheric Clouds ◽  
Mesospheric Clouds
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