scholarly journals Study on the impact of sudden stratosphere warming in the upper mesosphere-lower thermosphere regions using satellite and HF radar measurements

2010 ◽  
Vol 10 (7) ◽  
pp. 3397-3404 ◽  
Author(s):  
N. Mbatha ◽  
V. Sivakumar ◽  
S. B. Malinga ◽  
H. Bencherif ◽  
S. R. Pillay
Keyword(s):  
South African ◽  
Lower Thermosphere ◽  
Hf Radar ◽  
Wind Data ◽  
Zonal Winds ◽  
Broadband Emission ◽  
Radar Network ◽  
Radar Measurements ◽  
Environmental Prediction ◽  
The Impact

Abstract. The occurrence of a sudden stratospheric warming (SSW) excites disturbances in the mesosphere-lower thermospheric (MLT) wind and temperature. Here, we have examined the high frequency (HF) radar wind data from the South African National Antarctic Expedition, SANAE (72° S, 3° W), a radar which is part of the Super Dual Auroral Radar Network (SuperDARN). Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) on board the Thermosphere-Ionosphere-Mesosphere-Energetics and Dynamics (TIMED) satellite temperature data and National Centre for Environmental Prediction (NCEP) temperature and wind data are used to investigate the dynamical effects of the unprecedented September 2002 SSW in the Antarctica stratosphere and MLT. The mean zonal wind (from SANAE HF radar) at the MLT shows reversal approximately 7 days before the reversal at 10 hPa (from NCEP). This indicates that there was a downwards propagation of circulation disturbance. Westerly zonal winds dominate the winter MLT, but during the 2002 winter there are many periods of westward winds observed compared to other years. The normalised power spectrums of both meridional and zonal winds show presence of planetary waves (of ~14-day period) before the occurrence of the SSW. The SABER vertical temperature profiles indicated the cooling of the MLT region before the SSW event.

scholarly journals Study on the impact of sudden stratosphere warming in the upper mesosphere-lower thermosphere regions using satellite and HF radar measurements

2009 ◽  
Vol 9 (6) ◽  
pp. 23051-23072 ◽  
Author(s):  
N. Mbatha ◽  
V. Sivakumar ◽  
S. B. Malinga ◽  
H. Bencherif ◽  
S. R. Pillay
Keyword(s):  
South African ◽  
Lower Thermosphere ◽  
Hf Radar ◽  
Wind Data ◽  
Zonal Winds ◽  
Broadband Emission ◽  
Radar Network ◽  
Radar Measurements ◽  
Environmental Prediction ◽  
The Impact

Abstract. The occurrence of sudden stratospheric warming (SSW) excites disturbances in the mesosphere-lower thermospheric (MLT) wind and temperature. Here, we have examined the high frequency (HF) radar wind data from the South African National Antarctic Expedition, SANAE (72° S, 3° W), a radar which is part of the Super Dual Auroral Radar Network (SuperDARN). Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) on board the Thermosphere-Ionosphere-Mesosphere-Energetics and Dynamics (TIMED) satellite temperature data and National Centre for Environmental Prediction (NCEP) temperature and wind data were use to investigate the dynamical effects of the unprecedented September 2002 SSW in the Antarctica stratosphere and MLT. The mean zonal wind (from SANAE HF radar) at the MLT shows reversal in approximately 7 days before the reversal at 10 hPa (from NCEP). This indicates that there was a downwards propagation of circulation disturbance. Westerly zonal winds dominate the winter MLT, but during the 2002 winter there were many periods of westward winds observed compared to other years. The dynamic spectrums of both meridional and zonal winds show presence of planetary waves (of ~14-day period) before the occurrence of the SSW. The SABER vertical temperature profiles indicated the cooling of the MLT region before the SSW event.

scholarly journals Large-Scale Waves in the Mesosphere and Lower Thermosphere Observed by SABER

2005 ◽  
Vol 62 (12) ◽  
pp. 4384-4399 ◽  
Author(s):  
Rolando R. Garcia ◽  
Ruth Lieberman ◽  
James M. Russell ◽  
Martin G. Mlynczak
Keyword(s):  
Large Scale ◽  
Middle Atmosphere ◽  
Lower Thermosphere ◽  
Normal Modes ◽  
Zonal Winds ◽  
Broadband Emission ◽  
Summer Hemisphere ◽  
Mean Structure ◽  
Mesosphere And Lower Thermosphere ◽  
The Tropics

Abstract Observations made by the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument on board NASA’s Thermosphere–Ionosphere–Mesosphere Energetics and Dynamics (TIMED) satellite have been processed using Salby’s fast Fourier synoptic mapping (FFSM) algorithm. The mapped data provide a first synoptic look at the mean structure and traveling waves of the mesosphere and lower thermosphere (MLT) since the launch of the TIMED satellite in December 2001. The results show the presence of various wave modes in the MLT, which reach largest amplitude above the mesopause and include Kelvin and Rossby–gravity waves, eastward-propagating diurnal oscillations (“non-sun-synchronous tides”), and a set of quasi-normal modes associated with the so-called 2-day wave. The latter exhibits marked seasonal variability, attaining large amplitudes during the solstices and all but disappearing at the equinoxes. SABER data also show a strong quasi-stationary Rossby wave signal throughout the middle atmosphere of the winter hemisphere; the signal extends into the Tropics and even into the summer hemisphere in the MLT, suggesting ducting by westerly background zonal winds. At certain times of the year, the 5-day Rossby normal mode and the 4-day wave associated with instability of the polar night jet are also prominent in SABER data.

scholarly journals Signatures of 3–6 day planetary waves in the equatorial mesosphere and ionosphere

2006 ◽  
Vol 24 (12) ◽  
pp. 3343-3350 ◽  
Author(s):  
H. Takahashi ◽  
C. M. Wrasse ◽  
D. Pancheva ◽  
M. A. Abdu ◽  
I. S. Batista ◽  
...  
Keyword(s):  
Lower Thermosphere ◽  
Equatorial Region ◽  
Kelvin Wave ◽  
Plasma Bubble ◽  
Zonal Winds ◽  
Wave Characteristics ◽  
Ascension Island ◽  
Spread F ◽  
E Region ◽  
Radar Measurements

Abstract. Common periodic oscillations have been observed in meteor radar measurements of the MLT winds at Cariri (7.4° S, 36.5° W) and Ascension Island (7.9° S, 14.4° W) and in the minimum ionospheric virtual height, h'F, measured at Fortaleza (3.9° S, 38.4° W) in 2004, all located in the near equatorial region. Wavelet analysis of these time series reveals that there are 3–4-day, 6–8-day and 12–16-day oscillations in the zonal winds and h'F. The 3–4 day oscillation appeared as a form of a wave packet from 7–17 August 2004. From the wave characteristics analyzed this might be a 3.5-day Ultra Fast Kelvin wave. The 6-day oscillation in the mesosphere was prominent during the period of August to November. In the ionosphere, however, it was apparent only in November. Spectral analysis suggests that this might be a 6.5-day wave previously identified. The 3.5-day and 6.5-day waves in the ionosphere could have important roles in the initiation of equatorial spread F (plasma bubble). These waves might modulate the post-sunset E×B uplifting of the base of the F-layer via the induced lower thermosphere zonal wind and/or the E-region conductivity.

scholarly journals Meteor radar measurements of MLT winds near the equatorial electro jet region over Thumba (8.5° N, 77° E): comparison with TIDI observations

2011 ◽  
Vol 29 (7) ◽  
pp. 1209-1214 ◽  
Author(s):  
S. R. John ◽  
K. V. Subrahmanyam ◽  
G. Manju ◽  
Q. Wu ◽  
Keyword(s):  
Lower Thermosphere ◽  
Equatorial Electrojet ◽  
Hf Radar ◽  
Meteor Radar ◽  
Radar Observations ◽  
Diurnal Cycles ◽  
Four Seasons ◽  
E Region ◽  
Radar Measurements ◽  
Wind Profiles

Abstract. The All-Sky interferometric meteor (SKYiMET) radar (MR) derived winds in the vicinity of the equatorial electrojet (EEJ) are discussed. As Thumba (8.5° N, 77° E; dip lat. 0.5° N) is under the EEJ belt, there has been some debate on the reliability of the meteor radar derived winds near the EEJ height region. In this regard, the composite diurnal variations of zonal wind profiles in the mesosphere-lower thermosphere (MLT) region derived from TIMED Doppler Interferometer (TIDI) and ground based meteor radar at Thumba are compared. In this study, emphasis is given to verify the meteor radar observations at 98 km height region, especially during the EEJ peaking time (11:00 to 14:00 LT). The composite diurnal cycles of zonal winds over Thumba are constructed during four seasons of the year 2006 using TIDI and meteor radar observations, which showed good agreement especially during the peak EEJ hours, thus assuring the reliability of meteor radar measurements of neutral winds close to the EEJ height region. It is evident from the present study that on seasonal scales, the radar measurements are not biased by the EEJ. The day-time variations of HF radar measured E-region drifts at the EEJ region are also compared with MR measurements to show there are large differences between ionospheric drifts and MR measurements. The significance of the present study lies in validating the meteor radar technique over Thumba located at magnetic equator by comparing with other than the radio technique for the first time.

scholarly journals Super Dual Auroral Radar Network observations of fluctuations in the spectral distribution of near range meteor echoes in the upper mesosphere and lower thermosphere

2001 ◽  
Vol 19 (4) ◽  
pp. 425-434 ◽  
Author(s):  
N. F. Arnold ◽  
T. R. Robinson ◽  
M. Lester ◽  
P. B. Byrne ◽  
P. J. Chapman
Keyword(s):  
Middle Atmosphere ◽  
Lower Thermosphere ◽  
Spectral Width ◽  
Hf Radar ◽  
Model Calculations ◽  
Radar Network ◽  
Mesosphere And Lower Thermosphere ◽  
Solar Uv Irradiance ◽  
Thermospheric Dynamics

Abstract. The Doppler shifts of meteor echoes measured by the SuperDARN HF radar network have been used in several studies to observe neutral winds in the upper mesosphere and lower thermosphere region. In the absence of accurate height information for individual meteors, it has been necessary to assume a statistical mean meteor layer where the variations in altitude were not correlated to changes in the horizontal winds. Observations of spectral width distribution variations made by the radars allow an independent determination of the systematic error in the height. We have investigated the dependence of this distribution on a number of factors including the radar geometry, diurnal and seasonal cycles, variations in solar UV irradiance and geomagnetic activity. Changes in the altitude of the mean meteor layer observed at different radar ranges provide us with some insight into the structure of the upper mesosphere and the lower thermosphere within which the meteors are being ablated. An examination of the spectral widths, as measured by the CUT-LASS Finland radar, in the days preceding and following a Storm Sudden Commencement in April 1997, illustrates how the spectral properties of the observed region can be affected. The variations in the widths were consistent with model calculations of the changes to the temperature profile over this interval. Further refinements in the determination of the spectral width are outlined for future experiments.Key words. Meterology and atmospheric dynamics (middle atmosphere dynamics; thermospheric dynamics; instruments and techniques)

Some Reflections on Reparation in Post-Apartheid South Africa, using a Couple Therapy Intervention as a Microcosm of South African Society

2011 ◽  
Vol 1 (2) ◽  
Author(s):  
Andrea Hill ◽  
Sylvia Poss
Keyword(s):  
South Africa ◽  
South African ◽  
Couple Therapy ◽  
South African Society ◽  
Depressive Position ◽  
Central Hypothesis ◽  
Transference And Countertransference ◽  
Constructive Engagement ◽  
The Impact ◽  
Therapy Intervention

The paper addresses the question of reparation in post-apartheid South Africa. The central hypothesis of the paper is that in South Africa current traumas or losses, such as the 2008 xenophobic attacks, may activate a ‘shared unconscious phantasy’ of irreparable damage inflicted by apartheid on the collective psyche of the South African nation which could block constructive engagement and healing. A brief couple therapy intervention by a white therapist with a black couple is used as a ‘microcosm’ to explore this question. The impact of an extreme current loss, when earlier losses have been sustained, is explored. Additionally, the impact of racial difference on the transference and countertransference between the therapist and the couple is explored to illustrate factors complicating the productive grieving and working through of the depressive position towards reparation.

ADOLESCENTS' PERCEPTIONS OF STRESSORS CONTRIBUTING TO SUICIDAL BEHAVIOUR

2017 ◽  
Vol 26 (2) ◽  
pp. 192-213
Author(s):  
Henriëtte Van den Berg ◽  
Hester Tancred ◽  
Dap Louw
Keyword(s):  
South African ◽  
Family Environment ◽  
Family Relationships ◽  
Suicidal Behaviour ◽  
Stressful Life Events ◽  
Qualitative Content Analysis ◽  
Peer Group ◽  
Conservation Of Resources ◽  
Western Cape ◽  
The Impact

South African adolescents show increased levels of suicidal behaviour. This article explores the perceptions of adolescents at risk of suicide regarding the psychosocial stressors they believe contribute to suicidal behaviour among South African adolescents. This study was conducted on 214 adolescents from the Western Cape Province with a high suicide risk. The group was selected on the basis of their high scores on the Suicidal Ideation Questionnaire. A qualitative content analysis was performed with their responses on a question about the reasons for adolescent suicide. The analysis highlighted risk factors relating to substance abuse, negative emotional experiences, lack of self-esteem, problem-solving ability and hope for the future; negative family environment and conflict in family relationships; peer group and romantic relationships; stressful life events; and socioeconomic factors. Guided by the Conservation of Resources (COR) theory suggestions were made for adolescent resource development to counter-act the impact of the various stressors they experience.

The impact of climate temperature on counts, recovery, and death rates due to SARS-CoV-2 in South Africa. (Preprint)

2020 ◽  
Author(s):  
Neven Chetty ◽  
Bamise Adeleye ◽  
Abiola Olawale Ilori
Keyword(s):  
South Africa ◽  
South African ◽  
Death Rate ◽  
Western Cape ◽  
Warm Climate ◽  
The South ◽  
Recovery Rates ◽  
Death Rates ◽  
Online Resource ◽  
The Impact

BACKGROUND The impact of climate temperature on the counts (number of positive COVID-19 cases reported), recovery, and death rates of COVID-19 cases in South Africa's nine provinces was investigated. The data for confirmed cases of COVID-19 were collected for March 25 and June 30, 2020 (14 weeks) from South Africa's Government COVID-19 online resource, while the daily provincial climate temperatures were collected from the website of the South African Weather Service. Our result indicates that a higher or lower climate temperature does not prevent or delay the spread and death rates but shows significant positive impacts on the recovery rates of COVID-19 patients. Thus, it indicates that the climate temperature is unlikely to impose a strict limit on the spread of COVID-19. There is no correlation between the cases and death rates, an indicator that no particular temperature range is closely associated with a faster or slower death rate of COVID-19 patients. As evidence from our study, a warm climate temperature can only increase the recovery rate of COVID-19 patients, ultimately impacting the death and active case rates and freeing up resources quicker to enable health facilities to deal with those patients' climbing rates who need treatment. OBJECTIVE This study aims to investigate the impact of climate temperature variation on the counts, recovery, and death rates of COVID-19 cases in all South Africa's provinces. The findings were compared with those of countries with comparable climate temperature values. METHODS The data for confirmed cases of COVID-19 were collected for March 25 and June 30 (14 weeks) for South African provinces, including daily counts, death, and recovery rates. The dates were grouped into two, wherein weeks 1-5 represent the periods of total lockdown to contain the spread of COVID-19 in South Africa. Weeks 6-14 are periods where the lockdown was eased to various levels 4 and 3. The daily information of COVID-19 count, death, and recovery was obtained from South Africa's Government COVID-19 online resource (https://sacoronavirus.co.za). Daily provincial climate temperatures were collected from the website of the South African Weather Service (https://www.weathersa.co.za). The provinces of South Africa are Eastern Cape, Western Cape, Northern Cape, Limpopo, Northwest, Mpumalanga, Free State, KwaZulu-Natal, Western Cape, and Gauteng. Weekly consideration was given to the daily climate temperature (average minimum and maximum). The recorded values were considered, respectively, to be in the ratio of death-to-count (D/C) and recovery-to-count (R/C). Descriptive statistics were performed for all the data collected for this study. The analyses were performed using the Person’s bivariate correlation to analyze the association between climate temperature, death-to-count, and recovery-to-count ratios of COVID-19. RESULTS The results showed that higher climate temperatures aren't essential to avoid the COVID-19 from being spread. The present results conform to the reports that suggested that COVID-19 is unlike the seasonal flu, which does dissipate as the climate temperature rises [17]. Accordingly, the ratio of counts and death-to-count cannot be concluded to be influenced by variations in the climate temperatures within the study areas. CONCLUSIONS The study investigates the impact of climate temperature on the counts, recovery, and death rates of COVID-19 cases in all South Africa's provinces. The findings were compared with those of countries with comparable climate temperatures as South Africa. Our result indicates that a higher or lower climate temperature does not prevent or delay the spread and death rates but shows significant positive impacts on the recovery rates of COVID-19 patients. Warm climate temperatures seem not to restrict the spread of the COVID-19 as the count rate was substantial at every climate temperatures. Thus, it indicates that the climate temperature is unlikely to impose a strict limit on the spread of COVID-19. There is no correlation between the cases and death rates, an indicator that there is no particular temperature range of the climatic conditions closely associated with a faster or slower death rate of COVID-19 patients. However, other shortcomings in this study's process should not be ignored. Some other factors may have contributed to recovery rates, such as the South African government's timely intervention to announce a national lockout at the early stage of the outbreak, the availability of intensive medical care, and social distancing effects. Nevertheless, this study shows that a warm climate temperature can only help COVID-19 patients recover more quickly, thereby having huge impacts on the death and active case rates.

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