scholarly journals On the origin of the mesospheric quasi-stationary planetary waves in the unusual Arctic winter 2015/16

2017 ◽  
Author(s):  
Vivien Matthias ◽  
Manfred Ern
Keyword(s):  
Planetary Wave ◽  
Polar Night ◽  
Model Studies ◽  
Broadband Emission ◽  
Time Period ◽  
Variable Gravity ◽  
Time Periods ◽  
Stationary Planetary Wave ◽  
Second Period

Abstract. The mid winter 2015/16 was characterized by an unusually strong polar night jet (PNJ) and by extraordinarily large stationary planetary wave (SPW) amplitudes in the subtropical mesosphere. The aim of this study is to find the origin of these mesospheric SPWs in mid winter 2015/16. The time period studied here is split into two time periods. The first period runs from late December 2015 until early January 2016 and the second period from early January until mid January 2016. While the SPW 1 dominates in the subtropical mesosphere in Period I, it is the SPW 2 that dominates in Period II. There are three possibilities how SPWs can occur in the mesosphere: 1) they propagate upward from the stratosphere, 2) they are in situ generated by longitudinally variable gravity wave (GW) drag, or 3) they are in situ generated by barotropic and/or baroclinic instabilities. Using global satellite observations from the Microwave Limb Sounder (MLS) and from the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) the origin of the mesospheric SPWs is investigated for both time periods. We found that due to the strong PNJ the SPWs were not able to propagate upward into the mesosphere northward of 50°N but were deflected upward and equatorward into the subtropical mesosphere. We show that the SPWs observed in the subtropical mesosphere are the same SPWs as in the mid-latitudinal stratosphere. At the same time we found evidence that the mesospheric SPWs in polar latitudes were in situ generated by longitudinally variable GW drag and that there is a mixture of in situ generation by longitudinally variable GW drag and by instabilities in mid latitudes. Our results based on observations show that every three mechanisms, upward propagating SPW and in situ generated SPWs by longitudinally variable GW drag and instabilities can act at the same time which confirms earlier model studies. Additionally, a possible contribution or impact of the unusually strong SPWs in the subtropical mesosphere to the disruption of the QBO in the same winter is discussed.

scholarly journals On the origin of the mesospheric quasi-stationary planetary waves in the unusual Arctic winter 2015/2016

2018 ◽  
Vol 18 (7) ◽  
pp. 4803-4815 ◽  
Author(s):  
Vivien Matthias ◽  
Manfred Ern
Keyword(s):  
Planetary Wave ◽  
Polar Night ◽  
Quasi Biennial Oscillation ◽  
Model Studies ◽  
Broadband Emission ◽  
Variable Gravity ◽  
Stationary Planetary Wave ◽  
Second Period ◽  
Biennial Oscillation

Abstract. The midwinter 2015/2016 was characterized by an unusually strong polar night jet (PNJ) and extraordinarily large stationary planetary wave (SPW) amplitudes in the subtropical mesosphere. The aim of this study is, therefore, to find the origin of these mesospheric SPWs in the midwinter 2015/2016 study period. The study duration is split into two periods: the first period runs from late December 2015 until early January 2016 (Period I), and the second period from early January until mid-January 2016 (Period II). While the SPW 1 dominates in the subtropical mesosphere in Period I, it is the SPW 2 that dominates in Period II. There are three possibilities explaining how SPWs can occur in the mesosphere: (1) they propagate upward from the stratosphere, (2) they are generated in situ by longitudinally variable gravity wave (GW) drag, or (3) they are generated in situ by barotropic and/or baroclinic instabilities. Using global satellite observations from the Microwave Limb Sounder (MLS) and the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) the origin of the mesospheric SPWs is investigated for both time periods. We find that due to the strong PNJ the SPWs were not able to propagate upward into the mesosphere northward of 50∘ N but were deflected upward and equatorward into the subtropical mesosphere. We show that the SPWs observed in the subtropical mesosphere are the same SPWs as in the mid-latitudinal stratosphere. Simultaneously, we find evidence that the mesospheric SPWs in polar latitudes were generated in situ by longitudinally variable GW drag and that there is a mixture of in situ generation by longitudinally variable GW drag and by instabilities at mid-latitudes. Our results, based on observations, show that the abovementioned three mechanisms can act at the same time which confirms earlier model studies. Additionally, the possible contribution from, or impact of, unusually strong SPWs in the subtropical mesosphere to the disruption of the quasi-biennial oscillation (QBO) in the same winter is discussed.

Solar Tides as Revealed by Measurements of Mesosphere Temperature by the MLS Experiment on UARS

2006 ◽  
Vol 63 (7) ◽  
pp. 1776-1797 ◽  
Author(s):  
Jeffrey M. Forbes ◽  
Dong Wu
Keyword(s):  
Nonlinear Interaction ◽  
General Circulation ◽  
Planetary Wave ◽  
Middle Atmosphere ◽  
Lower Thermosphere ◽  
General Circulation Models ◽  
Rich Mixture ◽  
Tidal Theory ◽  
Stationary Planetary Wave

Abstract Temperatures between 25 and 86 km measured by the Microwave Limb Sounder (MLS) experiment on the Upper Atmosphere Research Satellite (UARS) are analyzed to delineate diurnal, semidiurnal, and terdiurnal tidal structures and stationary planetary waves. These Fourier components are determined from temperatures averaged in bins covering 5° latitude, 30° longitude and 1 h in local time. This study confirms the presence of diurnal nonmigrating tides with zonal wavenumbers s = 0, 2, −3 [s > 0 (s < 0) implying westward (eastward) propagation] and semidiurnal tides with s = 1 and 3, and some components of lesser importance that were previously determined from UARS wind measurements near 95 km. The seasonal–latitudinal and height structures of these components are now revealed, and utilized to aid in interpreting their behaviors and ascertaining their origins. New discoveries include the terdiurnal s = 2 and s = 4 components, and trapped nonmigrating diurnal tides with s = 0 and s = 2. The former are likely to arise from nonlinear interaction between the migrating (s = 3) terdiurnal tide and the stationary planetary wave with s = 1. The latter may reflect the presence of a longitude-dependent in situ heat source, or in situ nonlinear interaction between the migrating diurnal tide and a stationary planetary wave with s = 1. The present results provide a rich mixture of observational results to challenge both mechanistic and general circulation models of the middle atmosphere. In addition, internal consistency is established between the MLS tidal temperatures at 86 km and previously derived tidal winds at 95 km within the context of tidal theory. This result represents one step in the validation of measurements required for successful application of data-model assimilation techniques to the mesosphere and lower thermosphere.

Notes from the Polar Night

2020 ◽  
Vol 9 (4) ◽  
pp. 35-43
Author(s):  
Chris Ingraham
Keyword(s):  
Global Warming ◽  
The Sun ◽  
Polar Night ◽  
Academic Scholarship

Drawing from in situ fieldwork in Longyearbyen, Svalbard, the northernmost settlement on Earth, these notes bring out the affective, ambient, and atmospheric power of extended darkness during the polar night, when the sun does not appear above the horizon for several months at a time. Each entry is composed of 113 words to reflect the number of days without light in Longyearbyen during the winter of my visit. Through a mixture of ethnographic observations, researched academic scholarship, and some endeavors of poetic worldmaking, these notes attempt to evoke the ineffable force of global warming by performing the sort of acutely observed and felt attentiveness to planetary being that is needed for our time.

scholarly journals Longitudinal birth cohort study finds that life-course frailty associates with later-life heart size and function

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Constantin-Cristian Topriceanu ◽  
James C. Moon ◽  
Rebecca Hardy ◽  
Nishi Chaturvedi ◽  
Alun D. Hughes ◽  
...  
Keyword(s):  
Life Course ◽  
Birth Cohort ◽  
Left Ventricular ◽  
Step Change ◽  
Deficit Accumulation ◽  
Cardiac Phenotype ◽  
Time Period ◽  
Time Periods ◽  
The Life Course ◽  
Health Deficit

AbstractA frailty index (FI) counts health deficit accumulation. Besides traditional risk factors, it is unknown whether the health deficit burden is related to the appearance of cardiovascular disease. In order to answer this question, the same multidimensional FI looking at 45-health deficits was serially calculated per participant at 4 time periods (0–16, 19–44, 45–54 and 60–64 years) using data from the 1946 Medical Research Council (MRC) British National Survey of Health and Development (NSHD)—the world’s longest running longitudinal birth cohort with continuous follow-up. From these the mean and total FI for the life-course, and the step change in deficit accumulation from one time period to another was derived. Echocardiographic data at 60–64 years provided: ejection fraction (EF), left ventricular mass indexed to body surface area (LVmassi, BSA), myocardial contraction fraction indexed to BSA (MCFi) and E/e′. Generalized linear models assessed the association between FIs and echocardiographic parameters after adjustment for relevant covariates. 1375 participants were included. For each single new deficit accumulated at any one of the 4 time periods, LVmassi increased by 0.91–1.44% (p < 0.013), while MCFi decreased by 0.6–1.02% (p < 0.05). A unit increase in FI at age 45–54 and 60–64, decreased EF by 11–12% (p < 0.013). A single health deficit step change occurring between 60 and 64 years and one of the earlier time periods, translated into higher odds (2.1–78.5, p < 0.020) of elevated LV filling pressure. Thus, the accumulation of health deficits at any time period of the life-course associates with a maladaptive cardiac phenotype in older age, dominated by myocardial hypertrophy and poorer function.

scholarly journals Comorbid disease burden among MS patients 1968–2012: A Swedish register–based cohort study

2020 ◽  
pp. 135245852091049 ◽  
Author(s):  
Kelsi A Smith ◽  
Sarah Burkill ◽  
Ayako Hiyoshi ◽  
Tomas Olsson ◽  
Shahram Bahmanyar ◽  
...  
Keyword(s):  
General Population ◽  
Age Groups ◽  
Comorbid Disease ◽  
Hazard Ratios ◽  
Time Period ◽  
Younger Age ◽  
Cardiovascular Depression ◽  
Prevalence Prevalence ◽  
Time Periods ◽  
Prevalence Ratios

Background: People with multiple sclerosis (pwMS) have increased comorbid disease (CMD) risk. Most previous studies have not considered overall CMD burden. Objective: To describe lifetime CMD burden among pwMS. Methods: PwMS identified using Swedish registers between 1968 and 2012 ( n = 25,476) were matched by sex, age, and county of residence with general-population comparators ( n = 251,170). Prevalence, prevalence ratios (PRs), survival functions, and hazard ratios by MS status, age, and time period compared seven CMD: autoimmune, cardiovascular, depression, diabetes, respiratory, renal, and seizures. Results: The magnitude of the PRs for each CMD and age group decreased across time, with higher PRs in earlier time periods. Before 1990, younger age groups had higher PRs, and after 1990, older age groups had higher PRs. Male pwMS had higher burden compared with females. Overall, renal, respiratory, and seizures had the highest PRs. Before 2001, 50% of pwMS received a first/additional CMD diagnosis 20 years prior to people without MS, which reduced to 4 years after 2001. PwMS had four times higher rates of first/additional diagnoses in earlier time periods, which reduced to less than two times higher in recent time periods compared to people without MS. Conclusion: Swedish pwMS have increased CMD burden compared with the general population, but this has reduced over time.

Comparison of Key Characteristics of Remarkable SSW Events in the Southern and Northern Hemisphere

2021 ◽  
Author(s):  
Michal Kozubek ◽  
Peter Krizan
Keyword(s):  
Northern Hemisphere ◽  
Planetary Wave ◽  
Polar Vortex ◽  
Wave Number ◽  
Strong Activity ◽  
Key Characteristics ◽  
Zonal Wave Number ◽  
Show Difference ◽  
Temperature Enhancement ◽  
Stationary Planetary Wave

&lt;p&gt;An exceptionally strong sudden stratospheric warming (SSW) in the Southern Hemisphere (SH) during September 2019 was observed. Because SSW in the SH is very rare, comparison with the only recorded major SH SSW is done. According to World Meteorological Organization (WMO) definition, the SSW in 2019 has to be classified as minor. The cause of SSW in 2002 was very strong activity of stationary planetary wave with zonal wave-number (ZW) 2, which reached its maximum when the polar vortex split into two circulations with polar temperature enhancement by 30 K/week and it penetrated deeply to the lower stratosphere and upper troposphere. On the other hand, the minor SSW in 2019 involved an exceptionally strong wave-1 planetary wave and a large polar temperature enhancement by 50.8 K/week, but it affected mainly the middle and upper stratosphere. The strongest SSW in the Northern Hemisphere was observed in 2009. This study provides comparison of two strongest SSW in the SH and the strongest SSW in the NH to show difference between two hemispheres and possible impact to the lower or higher layers.&lt;/p&gt;

Health Communication for Hospice Care through Chinese media: Digital Topic Modeling Approach (Preprint)

2021 ◽  
Author(s):  
Qian Liu ◽  
Zequan Zheng ◽  
Jingsen Chen ◽  
Winghei Tsang ◽  
Jin Shan ◽  
...  
Keyword(s):  
Mass Media ◽  
Health Communication ◽  
Topic Modeling ◽  
Health Care Services ◽  
Hospice Care ◽  
Patient Treatment ◽  
News Reports ◽  
Care Services ◽  
Time Period ◽  
Second Period

BACKGROUND Hospice care, a type of end-of-life care provided for dying patients and their families, has been rooted in China since the 1980s. It can improve receivers’ quality of life as well as ease their economic burden. The Chinese mass media have continued to actively dispel misconceptions of hospice care and deliver the latest information to citizens. OBJECTIVE This study aimed to retrieve and analyze news reports on hospice care to gain insight into whether any differences exist in delivered heath information as time went by and the role the mass media played in health communication in recent years. METHODS We searched the Huike (WiseSearch) database for related news from Chinese mass media between 2014 and 2019. We set January 1, 2014 to December 31, 2016 as the first time period and January 1, 2017 to December 31, 2019 as the second time period. Python was used to complete the data cleaning process. We determined appropriate topic numbers for these two periods based on coherence score and applied the latent Dirichlet allocation topic modeling. Keywords of each topic and corresponding topics’ names were then generated. The topics were plotted into different circles and their distances on the two-dimensional plane was represented by multidimensional scaling. RESULTS After removing the duplicated and irrelevant news articles, we obtained a total of 2227 articles. We chose eight as the suitable topic number for both time periods and generated topics’ name and their keywords. The top three most reported topics in the first period were patient treatment, hospice care stories, and development of health care services and health insurance, accounting for 18.68% (n = 178), 16.58% (n = 158), and 14.17% (n = 135) of the collected reports, respectively. The top three most reported topics in the second period were hospice care stories, patient treatment, and development of health care services, accounting for 15.62% (n = 199), 15.38 (n = 15.38), and 14.27% (n = 182), respectively. CONCLUSIONS Topic modeling of news reports gives us a better understanding of patterns of health communication about hospice care by mass media. Chinese mass media frequently reported on hospice care in April due to a traditional Chinese festival. An increase in coverage in the second period was observed. These two periods share six similar topics, among which patient treatment outstrips hospice care stories as the most-reported topic in the second period, showing the humanistic spirit behind the reports. We suggest stakeholders cooperate with the mass media when planning to update policies.

scholarly journals Simultaneous and co-located wind measurements in the middle atmosphere by lidar and rocket-borne techniques

2016 ◽  
Vol 9 (8) ◽  
pp. 3911-3919 ◽  
Author(s):  
Franz-Josef Lübken ◽  
Gerd Baumgarten ◽  
Jens Hildebrand ◽  
Francis J. Schmidlin
Keyword(s):  
Middle Atmosphere ◽  
Systematic Difference ◽  
Horizontal Distance ◽  
In Situ Method ◽  
Time Period ◽  
Meridional Winds ◽  
Wind Measurements ◽  
In Situ Observations ◽  
Mean Differences

Abstract. We present the first comparison of a new lidar technique to measure winds in the middle atmosphere, called DoRIS (Doppler Rayleigh Iodine Spectrometer), with a rocket-borne in situ method, which relies on measuring the horizontal drift of a target (“starute”) by a tracking radar. The launches took place from the Andøya Space Center (ASC), very close to the ALOMAR observatory (Arctic Lidar Observatory for Middle Atmosphere Research) at 69° N. DoRIS is part of a steerable twin lidar system installed at ALOMAR. The observations were made simultaneously and with a horizontal distance between the two lidar beams and the starute trajectories of typically 0–40 km only. DoRIS measured winds from 14 March 2015, 17:00 UTC, to 15 March 2015, 11:30 UTC. A total of eight starute flights were launched successfully from 14 March, 19:00 UTC, to 15 March, 00:19 UTC. In general there is excellent agreement between DoRIS and the in situ measurements, considering the combined range of uncertainties. This concerns not only the general height structures of zonal and meridional winds and their temporal developments, but also some wavy structures. Considering the comparison between all starute flights and all DoRIS observations in a time period of ±20 min around each individual starute flight, we arrive at mean differences of typically ±5–10 m s−1 for both wind components. Part of the remaining differences are most likely due to the detection of different wave fronts of gravity waves. There is no systematic difference between DoRIS and the in situ observations above 30 km. Below ∼ 30 km, winds from DoRIS are systematically too large by up to 10–20 m s−1, which can be explained by the presence of aerosols. This is proven by deriving the backscatter ratios at two different wavelengths. These ratios are larger than unity, which is an indication of the presence of aerosols.

scholarly journals Visualizing Belief in Meritocracy, 1930–2010

2018 ◽  
Vol 4 ◽  
pp. 237802311881180 ◽  
Author(s):  
Jonathan J. B. Mijs
Keyword(s):  
Survey Data ◽  
Representative Sample ◽  
Western World ◽  
Birth Cohorts ◽  
Popular Belief ◽  
Time Period ◽  
Level Data ◽  
Two Measures ◽  
Time Periods ◽  
Over Time

In this figure I describe the long trend in popular belief in meritocracy across the Western world between 1930 and 2010. Studying trends in attitudes is limited by the paucity of survey data that can be compared across countries and over time. Here, I show how to complement survey waves with cohort-level data. Repeated surveys draw on a representative sample of the population to describe the typical beliefs held by citizens in a given country and period. Leveraging the fact that citizens surveyed in a given year were born in different time-periods allows for a comparison of beliefs across birth cohorts. The latter overlaps with the former, but considerably extends the time period covered by the data. Taken together, the two measures give a “triangulated” longitudinal record of popular belief in meritocracy. I find that in most countries, popular belief in meritocracy is (much) stronger for more recent periods and cohorts.

Sign in / Sign up

Export Citation Format

Share Document