Interhemispheric structure and variability of the 5-day planetary wave from meteor radar wind measurements

Abstract. A study of the quasi-5-day wave (5DW) was performed using meteor radars at conjugate latitudes in the Northern and Southern hemispheres. These radars are located at Esrange, Sweden (68° N) and Juliusruh, Germany (55° N) in the Northern Hemisphere, and at Tierra del Fuego, Argentina (54° S) and Rothera Station, Antarctica (68° S) in the Southern Hemisphere. The analysis was performed using data collected during simultaneous measurements by the four radars from June 2010 to December 2012 at altitudes from 84 to 96 km. The 5DW was found to exhibit significant short-term, seasonal, and interannual variability at all sites. Typical events had planetary wave periods that ranged between 4 and 7 days, durations of only a few cycles, and infrequent strongly peaked variances and covariances. Winds exhibited rotary structures that varied strongly among sites and between events, and maximum amplitudes up to ~ 20 m s−1. Mean horizontal velocity covariances tended to be largely negative at all sites throughout the interval studied.

Download Full-text

Burst of Unusual Quasi-10 day Wave During the 2019 Southern Sudden Stratospheric Warming

10.5194/egusphere-egu21-296 ◽

2021 ◽

Author(s):

Jack Wang ◽

Scott Palo ◽

Jeffrey Forbes ◽

John Marino ◽

Tracy Moffat-Griffin

Keyword(s):

Southern Hemisphere ◽

Planetary Wave ◽

Wave Activity ◽

Stratospheric Warming ◽

Atmospheric Conditions ◽

Meteor Radar ◽

Sudden Stratospheric Warming ◽

Zonal Wavenumber ◽

Wind Measurements ◽

Mlt Region

<div> <p>An unusual sudden stratospheric warming (SSW) occurred in the Southern hemisphere in September 2019. Ground-based and satellite observations show the presence of a transient westward-propagating quasi-10 day planetary wave with zonal wavenumber one during the SSW.&#160;The planetary wave&#160;activity&#160;maximizes in the MLT region&#160;approximately 10 days after the SSW onset. Analysis indicates the&#160;quasi-10 day planetary wave&#160;is symmetric about the equator which is contrary to theory for such planetary waves.&#160;</p> </div><div> <p>Observations from MLS and&#160;SABER&#160;provide a unique opportunity to study the global structure and evolution of the symmetric&#160;quasi-10 day wave&#160;with observations of both geopotential height&#160;and temperature during these unusual atmospheric conditions. The space-based measurements are combined with meteor radar wind measurements from Antarctica, providing a comprehensive view of the quasi-10 day wave activity in the southern hemisphere during this SSW. We will also present the results of our mesospheric and lower thermospheric analysis along with a preliminary analysis of the ionospheric response to these wave perturbations.</p> </div>

Download Full-text

Migrating and Non-Migrating Tides Observed in the Stratosphere from FORMOSAT-3/COSMIC Temperature Retrievals

10.5194/angeo-2019-140 ◽

2019 ◽

Author(s):

Uma Das ◽

William Ward ◽

Chen Jeih Pan ◽

Sanat Kumar Das

Keyword(s):

Planetary Wave ◽

Middle Atmosphere ◽

High Latitudes ◽

Short Term ◽

The Mean ◽

Tidal Variability ◽

Using Data ◽

Stationary Planetary Wave ◽

Linear Interactions ◽

Winter Hemisphere

Abstract. FORMOSAT-3/COSMIC temperature data during 2009 to 2010 are analysed for tides in the middle atmosphere from ~ 10 to 50 km. COSMIC is a set of six micro satellites in near sun synchronous orbits with 30° orbital separations and provides good phase space sampling of tides. Short term tidal variability is deduced by considering ± 10 days' data together. The DW1 tide is found to peak over the equator at 30 km. It maximises and slightly shifts poleward during winters and thus is attributed to ozone absorption. Over mid and high latitudes, DW1 and the non-migrating tides DS0 and DW2 are intermittent in nature. Numerical experiments in the current study show that these could be a result of aliasing as they are found to occur at times of steep rise or fall in the mean temperature, particularly during the SSW of 2010. Further, stationary planetary wave components are found to be of very large amplitudes in the northern hemispheres reaching 18 K at 30 km over 65° N. By using data from COSMIC over shorter durations, aliasing between SPW and non-migrating tides is reduced and thus results in the large amplitudes of the former. This study clearly indicates that non-linear interactions are not a very important source of generation of the non migrating tides in the high latitude winter hemisphere. There is also a modulation of SPW1 by ~ 60 days in the high latitudes, which was not seen earlier.

Download Full-text

Migrating and non-migrating tides observed in the stratosphere from FORMOSAT-3/COSMIC temperature retrievals

Annales Geophysicae ◽

10.5194/angeo-38-421-2020 ◽

2020 ◽

Vol 38 (2) ◽

pp. 421-435 ◽

Cited By ~ 1

Author(s):

Uma Das ◽

William E. Ward ◽

Chen Jeih Pan ◽

Sanat Kumar Das

Keyword(s):

Planetary Wave ◽

Middle Atmosphere ◽

High Latitudes ◽

Sudden Stratospheric Warming ◽

Short Term ◽

The Mean ◽

Tidal Variability ◽

Using Data ◽

Stationary Planetary Wave ◽

Linear Interactions

Abstract. Formosa Satellite-3 and Constellation Observing System for Meteorology, Ionosphere and Climate (FORMOSAT-3/COSMIC) temperature data during October 2009–December 2010 are analysed for tides in the middle atmosphere from ∼10 to 50 km. COSMIC is a set of six micro-satellites in near-Sun-synchronous orbits with 30∘ orbital separations that provides good phase space sampling of tides. Short-term tidal variability is deduced by considering ±10 d data together. The migrating diurnal (DW1) tide is found to peak over the Equator at 30 km. It maximises and slightly shifts poleward during winters. Over middle and high latitudes, DW1 and the non-migrating diurnal tides with wavenumber 0 (DS0) and wavenumber 2 (DW2) are intermittent in nature. Numerical experiments in the current study show that these could be a result of aliasing as they are found to occur at times of a steep rise or fall in the mean temperature, particularly during the sudden stratospheric warming (SSW) of 2010. Further, the stationary planetary wave component of wavenumber 1 (SPW1) is found to be of very large amplitudes in the Northern Hemisphere, reaching 18 K at 30 km over 65∘ N. By using data from COSMIC over shorter durations, it is shown that aliasing between stationary planetary wave and non-migrating tides is reduced and thus results in the large amplitudes of the former. This study clearly indicates that non-linear interactions are not a very important source for the generation of non-migrating tides in the middle- and high-latitude winter stratosphere. There is also a modulation of SPW1 by a ∼60 d oscillation in the high latitudes, which was not seen earlier.

Download Full-text

Higher Handgrip Strength Is Linked to Better Cognitive Performance in Chinese Adults with Hypertension

Brain Sciences ◽

10.3390/brainsci11080985 ◽

2021 ◽

Vol 11 (8) ◽

pp. 985

Author(s):

Shenghua Lu ◽

Fabian Herold ◽

Yanjie Zhang ◽

Yuruo Lei ◽

Arthur F. Kramer ◽

...

Keyword(s):

Cognitive Performance ◽

Short Term Memory ◽

Handgrip Strength ◽

Adult Health ◽

Linear Regression Models ◽

Chinese Adults ◽

Short Term ◽

Term Memory ◽

Using Data ◽

The Relationship

Objective: There is growing evidence that in adults, higher levels of handgrip strength (HGS) are linked to better cognitive performance. However, the relationship between HGS and cognitive performance has not been sufficiently investigated in special cohorts, such as individuals with hypertension who have an intrinsically higher risk of cognitive decline. Thus, the purpose of this study was to examine the relationship between HGS and cognitive performance in adults with hypertension using data from the Global Ageing and Adult Health Survey (SAGE). Methods: A total of 4486 Chinese adults with hypertension from the SAGE were included in this study. Absolute handgrip strength (aHGS in kilograms) was measured using a handheld electronic dynamometer, and cognitive performance was assessed in the domains of short-term memory, delayed memory, and language ability. Multiple linear regression models were fitted to examine the association between relative handgrip strength (rHGS; aHGS divided by body mass index) and measures of cognitive performance. Results: Overall, higher levels of rHGS were associated with higher scores in short-term memory (β = 0.20) and language (β = 0.63) compared with the lowest tertiles of rHGS. In male participants, higher HGS was associated with higher scores in short-term memory (β = 0.31), language (β = 0.64), and delayed memory (β = 0.22). There were no associations between rHGS and cognitive performance measures in females. Conclusion: We observed that a higher level of rHGS was associated with better cognitive performance among hypertensive male individuals. Further studies are needed to investigate the neurobiological mechanisms, including sex-specific differences driving the relationship between measures of HGS and cognitive performance in individuals with hypertension.

Download Full-text

Long-Term Development of Urban Agriculture: Resilience and Sustainability of Farmers Facing the Covid-19 Pandemic in Japan

Sustainability ◽

10.3390/su13084316 ◽

2021 ◽

Vol 13 (8) ◽

pp. 4316

Author(s):

Shingo Yoshida ◽

Hironori Yagi

Keyword(s):

Urban Agriculture ◽

Food Systems ◽

Direct Marketing ◽

Farming System ◽

Long Term Effects ◽

Short Term ◽

Short Supply ◽

Using Data ◽

Urban People

The coronavirus disease 2019 (Covid-19) pandemic has forced global food systems to face unprecedented uncertain shocks even in terms of human health. Urban agriculture is expected to be more resilient because of its short supply chain for urban people and diversified farming activities. However, the short-and long-term effects of the Covid-19 pandemic on urban farms remain unclear. This study aims to reveal the conditions for farm resilience to the Covid-19 pandemic in 2020 and the relationship between short-term farm resilience and long-term farm development using data from a survey of 74 farms located in Tokyo. The results are as follows. First, more than half of the sample farms increased their farm sales during this period. This resilience can be called the “persistence” approach. Second, short-term farm resilience and other sustainable farm activities contributed to improving farmers’ intentions for long-term farm development and farmland preservation. Third, the most important resilience attributes were the direct marketing, entrepreneurship, and social networks of farmers. We discussed the necessity of building farmers’ transformative capabilities for a more resilient urban farming system. These results imply that support to enhance the short-term resilience of urban farms is worth more than the short-term profit of the farms.

Download Full-text

Interannual variability in the troposphere and stratosphere of the southern hemisphere winter

Journal of Geophysical Research Atmospheres ◽

10.1029/98jd01042 ◽

1998 ◽

Vol 103 (D12) ◽

pp. 13787-13799 ◽

Cited By ~ 35

Author(s):

Yuhji Kuroda ◽

Kunihiko Kodera

Keyword(s):

Interannual Variability ◽

Southern Hemisphere ◽

Hemisphere Winter

Download Full-text

Determinants of Treasury-LIBOR Swap Spreads

Review of Pacific Basin Financial Markets and Policies ◽

10.1142/s0219091505000567 ◽

2005 ◽

Vol 08 (04) ◽

pp. 687-705 ◽

Cited By ~ 3

Author(s):

D. K. Malhotra ◽

Vivek Bhargava ◽

Mukesh Chaudhry

Keyword(s):

Interest Rate ◽

Interest Rates ◽

Default Risk ◽

Yield Curve ◽

Short Term ◽

Long Run ◽

Interest Rate Volatility ◽

Short Run ◽

Using Data ◽

Swap Spreads

Using data from the Treasury versus London Interbank Offer Swap Rates (LIBOR) for October 1987 to June 1998, this paper examines the determinants of swap spreads in the Treasury-LIBOR interest rate swap market. This study hypothesizes Treasury-LIBOR swap spreads as a function of the Treasury rate of comparable maturity, the slope of the yield curve, the volatility of short-term interest rates, a proxy for default risk, and liquidity in the swap market. The study finds that, in the long-run, swap spreads are negatively related to the yield curve slope and liquidity in the swap market. We also find that swap spreads are positively related to the short-term interest rate volatility. In the short-run, swap market's response to higher default risk seems to be higher spread between the bid and offer rates.

Download Full-text

Interannual variability of precipitable water

Annales Geophysicae ◽

10.1007/s00585-996-0464-1 ◽

1996 ◽

Vol 14 (4) ◽

pp. 464-467 ◽

Cited By ~ 1

Author(s):

R. P. Kane

Keyword(s):

Interannual Variability ◽

Southern Hemisphere ◽

Northern Hemisphere ◽

Precipitable Water ◽

Radiosonde Data ◽

High Latitudes ◽

Zonal Winds ◽

Low Latitudes ◽

Linear Trends

Abstract. The 12-month running means of the surface-to-500 mb precipitable water obtained from analysis of radiosonde data at seven selected locations showed three types of variability viz: (1) quasi-biennial oscillations; these were different in nature at different latitudes and also different from the QBO of the stratospheric tropical zonal winds; (2) decadal effects; these were prominent at middle and high latitudes and (3) linear trends; these were prominent at low latitudes, up trends in the Northern Hemisphere and downtrends in the Southern Hemisphere.

Download Full-text

Sex ratio effects on reproductive strategies in humans

Royal Society Open Science ◽

10.1098/rsos.140402 ◽

2015 ◽

Vol 2 (1) ◽

pp. 140402 ◽

Cited By ~ 53

Author(s):

Ryan Schacht ◽

Monique Borgerhoff Mulder

Keyword(s):

Sexual Selection ◽

Sex Ratio ◽

Ethnic Group ◽

Reproductive Strategies ◽

Situational Factors ◽

Male Mating ◽

Mating Effort ◽

Short Term ◽

Adult Sex Ratio ◽

Using Data

Characterizations of coy females and ardent males are rooted in models of sexual selection that are increasingly outdated. Evolutionary feedbacks can strongly influence the sex roles and subsequent patterns of sex differentiated investment in mating effort, with a key component being the adult sex ratio (ASR). Using data from eight Makushi communities of southern Guyana, characterized by varying ASRs contingent on migration, we show that even within a single ethnic group, male mating effort varies in predictable ways with the ASR. At male-biased sex ratios, men's and women's investment in mating effort are indistinguishable; only when men are in the minority are they more inclined towards short-term, low investment relationships than women. Our results support the behavioural ecological tenet that reproductive strategies are predictable and contingent on varying situational factors.

Download Full-text