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Diurnal and semi-diurnal coordinate variations observed in EUREF permanent GPS network - a case study for period from 2004.0 to 2006.9
Ján Hefty, Miroslava Igondová
Contributions to Geophysics and Geodesy , 2010, DOI: 10.2478/v10126-010-0010-8
Abstract: The 2.9-year interval of homogeneous and continuous observations at 29 European permanent GPS stations distributed all over the whole continent is analyzed for the short-periodic variations of site coordinates. In the literature seasonal terms in GPS coordinate series are well documented; the main objective of this paper is to investigate the existence of variations with shorter periods. We used the coordinate estimates obtained from 4-hour observing intervals which enabled identification of variations with diurnal and sub-diurnal periods. In the amplitude spectra of station time series we detected a set of dominant periodic terms which have exclusively diurnal and semi-diurnal tidal frequencies. The most significant are the diurnal S1, K1, O1 and semi-diurnal S2, K2, M2 waves. Their amplitudes are different for individual sites and they reach from sub-millimetre values up to ~ 3 mm for some stations situated close to the Atlantic coast. Uncertainties of estimated amplitudes are generally at the 0.3 mm level. The possible origin of the observed periodic variations is very complex. We interpret the observed coordinate variability as a superposition of potential deficiencies in used models of ocean tide loading displacements, effects of atmospheric tides, multipath, troposphere and ionosphere residual effects, and other phenomena with diurnal and semi-diurnal forcing as well as the unidentified GPS analysis imperfection. The geokinematical relevance of detected variations and their possible interpretation are discussed.
Modulation of cosmic rays at different cutoff rigidity
Agarwal, Rekha;Mishra, Rajesh K.;
Brazilian Journal of Physics , 2008, DOI: 10.1590/S0103-97332008000100021
Abstract: the present work deals with the study of first three harmonics of cosmic ray intensity on geo-magnetically quiet days over the period 1981-1993 for deep river and inuvik neutron monitoring stations having mid and low cutoff rigidity. the amplitude of first harmonic remains high for deep river having mid cutoff rigidity as compared to inuvik neutron monitor having low cutoff rigidity on quiet days. the diurnal amplitude significantly decreases and phase shifts towards an earlier time during solar activity minimum years at both deep river and inuvik. the amplitude of second harmonic significantly enhanced during solar activity minimum as well as maximum at deep river and remains low during solar activity maximum at inuvik, whereas the phase shifts towards an earlier time during solar maximum for both the stations. the amplitude of the third harmonic significantly enhanced during solar activity minimum at deep river and on solar activity minimum at inuvik, whereas the phase does not show any significant characteristics and fluctuates quite frequently. the amplitude of semi/tri-diurnal anisotropy has a good positive correlation, while the others (i.e. amplitude and phase) have very weak correlation with solar wind velocity on quiet days at deep river station during 1981-1993. the solar wind velocity significantly remains in the range 350 to 425 km/s i.e. being nearly average on quiet days. the amplitude and direction of the anisotropy on quiet days are weakly dependent on high-speed solar wind streams for two neutron monitoring station of mid and low cutoff rigidity threshold. the amplitude as well as direction of second harmonic has a good anti-correlation with imf bz and the product v x bz on quiet days at deep river station. however, the direction of second and third harmonic has a good anti-correlation with imf bz and the product v x bz on quiet days at inuvik station.
CEREBROVASCULAR ACCIDENT
Muhammad Ashraf
The Professional Medical Journal , 2001,
Abstract: Several studies performed worldwide have shown a diurnal variation of cerebrovascular accident(CVA) onset. OBJECTIVE: To assess the diurnal variations of CVA onset in our setup.DESIGN: Prospective study. SETTING: Allied and Divisional Headquarter (DHQ) Hospitals,Faisalabad. PERIOD: July 2000 to December 2000. PATIENTS & METHODS: All the strokepatients admitted during this period were studied especially for the time of onset of a stroke. RESULTS:Time frame was divided into four 6 hourly groups. Highest number of stroke onset was found in time periodbetween 6:00 hours to 12:00 hours group (224 out of 641, 34.94%). Major risk factors were uncontrolleddiabetes mellitus, hypertension and smoking in our setup. CONCLUSION: The onset of CVA is morecommon in early to late morning hours. Uncontrolled diabetes mellitus and hypertension should becontrolled properly to avoid the catastrophe of stroke.
Monitoring of 7Be atmospheric activity concentration using short term measurements
Papandreou Sotiria M.A.,Savva Marilia I.,Karfopoulos Konstantinos L.,Karangelos Dimitrios J.
Nuclear Technology and Radiation Protection , 2011, DOI: 10.2298/ntrp1102101p
Abstract: The activity concentration of 7Be in atmospheric aerosol can exhibit seasonal variations due to various physical processes taking place in the troposphere and stratosphere, as well as due to solar activity. An investigation of these variations has been carried out at the Nuclear Engineering Department of the National Technical University of Athens over a two year period (3/2008-4/2010). In the framework of this study, sampling and analysis methods were appropriately selected to allow for the observation of short-term 7Be air activity concentration variations, using a 4-hour sampling interval, while taking in consideration type A and type B uncertainties introduced in the measurements. In order to study the role of precipitation in surface air 7Be activity concentration variations, a procedure for collecting and analyzing rainwater was developed. The techniques used in the present study allowed for the observation of seasonal and diurnal 7Be concentration variations, as well as correlations between 7Be activity concentration and the meteorological parameters of air temperature and relative humidity.
Sq (H) Solar Variation at Yaoundé-Cameroon AMBER Station from 2011 to 2014  [PDF]
Messanga Etoundi Honoré, Fatma Anad, Ngabireng Claude Marie, Mbane Biouele César
International Journal of Geosciences (IJG) , 2017, DOI: 10.4236/ijg.2017.84029
Abstract: This paper presents the earth’s magnetic field variations on quiet days using data from 2011 to 2014 provided by the AMBER station located at the University of Yaoundé 1 (Cameroon), whose geographic and geomagnetic coordinates are respectively: (3.87°N, 11.52°E) and (5.8°S, 83.1°E). The variability of the H horizontal component of the Earth’s magnetic field was examined using the North (X) and East (Y) components of the earth’s magnetic field. The H component is then used to calculate and analyze the diurnal, monthly and seasonal Solar quiet variations Sq (H) observed in Yaoundé-Cameroon during quiet magnetic days. The results obtained show that the Sq (H) variations are seasonal. e.g., in Spring the Sq (H) amplitude (~72 nT) is larger than that of Autumn (~69 nT). The maximum values of Sq (H) vary from 48.8 nT to 57.12 nT in summer and from 41 nT to 60 nT in winter from the years 2011 to 2014. In general, these maximum values are observed around 12:00 and 13:00 in local time. These results show that the morphology of Sq (H) in Yaoundé is presented as a function of seasons. Moreover, the Sq (H) values are negative during morning hours (01:00 - 06:00) and afternoon hours (18:00 - 24:00) in local time throughout all months and all seasons. This significant negative excursion of Sq (H) in Yaoundé during the night time might be due to other physical processes such as storms or thunderclouds or to the existence of a strong induced current in Yaoundé which can affect the ground-based instruments. By referring to the solar cycle 24, our results show that the Sq (H) amplitude varies with the solar activity. The aim of this work is to analyze the diurnal, monthly and seasonal variations of Sq (H) observed in Yaoundé from 2011 to 2014.
Dopa-Responsive Dystonia with Diurnal Fluctuation: A Case Report of an 18 Year Old Nigerian
- , 2018,
Abstract: Dopa-responsive dystonia, also known as hereditary progressive dystonia with diurnal variation, is a genetic disease characterized by childhood or adolescent onset of dystonia and sometimes associated with parkinsonian features. This is a case report of an 18 year old Nigerian University undergraduate with features of difficulty in speaking, stiffness of the body, gait difficulties, coarse tremors and toe-walking. There was a very marked improvement of symptoms and signs within 24-48 hours of the commencement of SinemetTM (levodopa/ carbidopa) 125mg/12.5mg daily. The patient was discharged after 5 days with normal gait
Diurnal variation of nitrated polycyclic aromatic hydrocarbons in PM10 at a roadside site in Xiamen, China
Shuiping Wu,Bingyu Yang,Xinhong Wang,Huasheng Hong,Chungshin Yuan,
Shuiping Wu,Bingyu Yang,Xinhong Wang,Huasheng Hong,Chungshin Yuan
环境科学学报(英文版) , 2012,
Abstract: Intensive daytime and nighttime sampling was carried out from 23 Oct to 31 Dec 2008 to investigate the occurrence of nitrated polycyclic aromatic hydrocarbons (NPAHs) in PM10 at a roadside site in Xiamen, China. At the same time, six PM10 samples were collected from a nearby roadway tunnel for comparison. Six NPAHs, namely 9-nitroanthracene, 2-and 3-nitrofluoranthene, 1-nitropyrene, 7-nitrobenza]anthracene, and 6-nitrobenzoa]pyrene, were identified and quantified using GC/MS in negative ion chemical ionization mode. The average total concentration of six NPAHs (∑NPAHs) in the cold season (26 Nov-31 Dec) was 2.3 (daytime) and 9.9 (nighttime) times higher than those in the warm season. Significant statistical difference (p < 0.01, 2-tailed) of ∑NPAHs between daytime and nighttime was found during both the warm and cold seasons. NPAHs were significantly positively correlated with their parent PAHs and nitrogen dioxide but negatively correlated with ambient temperature. The ratio of 2 + 3-nitrofluoranthene to 1-nitropyrene exhibited a similar diurnal pattern as ∑NPAHs and was generally greater than 5, indicating the importance of secondary atmospheric formation. The diurnal variations of NPAHs were all influenced by the diurnal variations of PAHs, nitrogen dioxide, sunlight, and temperature. The daily inhalable exposure to the six NPAHs in the tunnel was much higher than the roadside values in the warm season but only slightly higher than those in the cold season.
An assessment of the atmospheric nitrogen budget on the South African Highveld
Kirsten S. Collett,Stuart J. Piketh,Kristy E. Ross
South African Journal of Science , 2010, DOI: 10.4102/sajs.v106i5/6.220
Abstract: Atmospheric reactive nitrogen concentrations on the South African Highveld have become a growing concern, with satellite images indicating very high nitrogen dioxide (NO2) concentrations in the region. This study investigated the nitrogen budget on the Highveld through the analysis of the concentration of the atmospheric nitrogen species on a temporal scale as well as the atmospheric conversion, transport and removal of these species. Data were collected at Eskom’s Elandsfontein ambient air quality monitoring site, which is centrally located on the industrialised Highveld. A year’s dataset from 2005 and 2006 was analysed and it was found that nitrogen oxide (NOx) concentrations were higher in winter as a result of stable atmospheric conditions, as well as prevalent westerly and north-westerly airflow, which transported emissions directly from the nearby power station sources to the monitoring site. Nitrate (NO3) concentrations also peaked during winter, with a distinct biomass burning peak during August 2005. Diurnally, NOx concentrations indicated a tall-stack industrial source, where concentrations peaked at midday. The NO3 concentrations were higher at night than during the day; during the day the NO3 radical is rapidly photolysed and nitrates cannot be produced. Case studies indicated that the conversion rate of nitric oxide (NO) to NO2 was highly variable as a result of varying atmospheric factors, which include time of day, dispersion, stability and regional atmospheric chemistry. These rates ranged from 11% to 59% per hour. Rates of dry deposition of NO, NO2 and NO3 were generally higher during winter as a result of higher atmospheric concentrations and increased atmospheric stability. Nitrogen was predominantly deposited as NO2 throughout the year, except during spring when NO3 deposition dominated. The total annual amount of nitrogen that was deposited to the Mpumalanga Highveld region was in the range of 6.7 kg/ha –13.1 kg/ha per year, which is well below the stipulated critical load value. Such deposition, therefore, should not pose significant threats to the natural environment on the Highveld. Between 4% and 15% of the total emitted nitrogen from power generation on the Highveld was deposited to the surface via wet and dry deposition. The remainder was advected out of the region.
Hourly Soil Temperature Variability and Estimation at Multiple Depths from Meteorological Data Using Multiple Linear Regression in a Tropical Semi-Arid Region of Burkina Faso  [PDF]
Fran？ois Dabilgou, Soumaila Gandema, Marcel Bawindsom Kébré, Zamantakonè Guillaume Ki, Zakarie Koalaga
Open Journal of Applied Sciences (OJAppS) , 2025, DOI: 10.4236/ojapps.2025.159188
Abstract: Accurate estimation of soil temperature is essential for understanding land–atmosphere interactions and supporting agricultural management in semi-arid regions. This study focuses on the analysis of hourly soil temperature variability and the performance of Multiple Linear Regression (MLR) models at depths of 10, 20, 30, and 40 cm in a tropical semi-arid soil of Burkina Faso. Using in situ meteorological data collected at the Tanghin (Saaba, Kadiogo) experimental site, the results reveal a progressive attenuation of temperature fluctuations with depth, confirming the buffering effect and thermal inertia of subsurface layers. A clear phase lag between soil and air temperatures was observed, increasing with depth and particularly evident beyond 20 cm, which reflects delayed heat propagation within the soil profile. MLR models performed reasonably well at shallow depths, especially when driven by a minimal set of meteorological predictors (Ta, BP, WS, RH), achieving R2 values up to 0.75 at 10 cm. However, their predictive ability declined with increasing depth and under wet-season conditions, where soil temperature becomes increasingly decoupled from atmospheric drivers. Moreover, the models struggled to reproduce full diurnal cycles, underestimating nighttime cooling and overestimating during the rainy season, likely due to limited sensitivity to soil moisture dynamics. These findings emphasize both the potential and the limitations of MLR in capturing subsurface thermal variability.
贵阳城区气温日变化特征及其季节差异分析
Diurnal Temperature Variations Characteristics of Urban Areas in Guiyang and Its Seasonal Difference  [PDF]
周林, 胡婕, 王君军, 罗乃兴, 彭科曼
Climate Change Research Letters (CCRL) , 2024, DOI: 10.12677/ccrl.2024.133067
Abstract: 基于贵阳国家气象观测站2011~2022年逐小时气温观测资料，分析了贵阳城区气温的日变化规律及季节差异特征。结果表明：贵阳城区日最高气温集中出现在15~16时，最低温度出现在06~08时。夏季日最低气温出现时间最早为06时，冬季出现时间最晚为08时，温度日变化的特征有明显的季节差异；日最高(低)气温出现率都存在“双峰”型结构，最高气温出现时间一年四季均较为集中，而最低气温出现时间在夏季最为集中，其余季节均较为分散。贵阳城区1 h最大正(负)变温时间集中在10~13时(18~20时)，升温和降温过程具有不对称性特征，升温比降温过程缓慢，最强变温过程发生在3 h以内；春季、夏季和秋季变温幅度较大，而冬季最小；最大正变温出现时间在冬季最为集中，夏季最为分散，而最大负变温出现时间在各月间的差异较大。
Based on hourly temperature datasets of Guiyang national ground meteorological observation stations from 2011 to 2022, the characteristics of diurnal temperature variations and seasonal differences over urban areas in Guiyang were analyzed. The results show as follows: The maximum high temperature in urban areas of Guiyang is concentrated on 15~16 o’clock, while the minimum low temperature at 06~08 o’clock in the daily cycle. In all seasons, the daily minimum temperature appears earliest at 06:00 in summer and the latest at 08:00 in winter. The diurnal temperature variations characteristics change obviously with the season. The occurrence of both daily maximum and minimum temperature exhibited “double-peak” structure. For the maximum high temperature, the emergence time is relatively concentrated throughout the year, while the emergence times of the minimum low temperature is centralized in summer but dispersive in other seasons. The one-hour maximum positive (negative) temperature change time over urban areas in Guiyang is concentrated on 10 to 13 o’clock (18 to 20 o’clock). The temperature rising and cooling changes are asymmetric, and the temperature rising changes more slowly than the temperature cooling. Analyses of the temperature change rate in different time intervals showed that the sharpest change takes place in three hours. The temperature change range is larger in spring, summer and autumn, and the smallest in winter. The probability distribution analysis of the occurrence time of the maximum temperature change shows that the time at which the maximum positive temperature appears is the most concentrated in winter but the most dispersive in summer. However, the time at which the maximum negative temperature appears exhibit significant difference in each month.
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