scholarly journals Global variation in the long-term seasonal changes observed in ionospheric F region data

2015 ◽  
Vol 33 (4) ◽  
pp. 449-455 ◽  
Author(s):  
C. J. Scott ◽  
R. Stamper
Keyword(s):  
Regional Variation ◽  
Critical Frequency ◽  
Relative Magnitude ◽  
Striking Similarity ◽  
Regional Variability ◽  
Data Set ◽  
Annual Variations ◽  
F Region ◽  
Region Data

Abstract. Long-term variability has previously been observed in the relative magnitude of annual and semi-annual variations in the critical frequency (related to the peak electron concentration) of the ionospheric F2 layer (foF2). In this paper we investigate the global patterns in such variability by calculating the time varying power ratio of semi-annual to annual components seen in ionospheric foF2 data sequences from 77 ionospheric monitoring stations around the world. The temporal variation in power ratios observed at each station was then correlated with the same parameter calculated from similar epochs for the Slough/Chilton data set (for which there exists the longest continuous sequence of ionospheric data). This technique reveals strong regional variation in the data, which bears a striking similarity to the regional variation observed in long-term changes to the height of the ionospheric F2 layer. We argue that since both the height and peak density of the ionospheric F2 region are influenced by changes to thermospheric circulation and composition, the observed long-term and regional variability can be explained by such changes. In the absence of long-term measurements of thermospheric composition, detailed modelling work is required to investigate these processes.

Primary Production in a Tidally Energetic Fjord: Evidence of Seasonal and Inter-annual Tidal Forcing

1989 ◽  
Vol 46 (12) ◽  
pp. 2166-2172 ◽  
Author(s):  
T. A. Kessler ◽  
T. R. Parsons
Keyword(s):  
Primary Production ◽  
Standing Stock ◽  
Covariance Structure ◽  
Static Stability ◽  
Data Set ◽  
Annual Variations ◽  
Basin Surface ◽  
Statistical Relationships ◽  
Inflow Jet

A long term data set collected from a tidally energetic sill fjord was analyzed for its statistical relationships between primary production indices and several represented environmental variables. The analysis identified variance and covariance structure in these variables implicating changes in water column clarity, in inter-annual variability of phytoplankton carbon uptake rate, and the static stability of basin surface water in phytoplankton standing stock. The biomass–stability relationship was found to be seasonally dependent, with biomass positively correlated with stability in the summer and negatively correlated in the spring/fall, and restricted to waters under the direct mixing influence of the tidal inflow jet. These statistical patterns are discussed in terms of a possible control of primary production by seasonal and inter-annual variations in tidal inflow buoyancy.

scholarly journals Prevalence and variability of use of home mechanical ventilators, positive airway pressure and oxygen devices in the Lombardy region, Italy

2018 ◽  
Vol 88 (1) ◽  
Author(s):  
Michele Vitacca ◽  
Luca Barbano ◽  
Daniele Colombo ◽  
Olivia Leoni ◽  
Enrico Guffanti
Keyword(s):  
Regional Variation ◽  
Airway Pressure ◽  
Positive Airway Pressure ◽  
Prescription Rate ◽  
Mechanical Ventilators ◽  
Billing Data ◽  
Regional Variability ◽  
Sleep Study ◽  
Lombardy Region

Few studies have analyzed the prevalence and accessibility of home mechanical ventilation (HMV) in Italy. We aimed to investigate the prevalence and prescription variability of HMV as well as of long-term oxygen therapy (LTOT) and continuous positive airway pressure (CPAP), in the Lombardy Region. Prescribing rates of HMV (both noninvasive and tracheostomies), CPAP (auto-CPAP, CPAP/other sleep machines) and LTOT (liquid-O2, O2-gas, concentrators) in the 15 Local Healthcare districts of Lombardy were gathered from billing data for 2012 and compared. Crude rates (per 100,000 population) and rates for the different healthcare districts were calculated. In 2012, 6325 patients were on HMV (crude prescription rate: 63/100,000) with a high variation across districts (8/100,000 in Milano 1 vs 150/100,000 in Pavia). There were 14,237 patients on CPAP (crude prescription rate: 142/100,000; CPAP/other sleep machines 95.3% vs auto-CPAP 4.7%) with also high intra-regional variation (56/100,000 in Mantova vs. 260/100,000 in Pavia). There were 21,826 patients on LTOT (prescription rate: 217/100,000 rate; liquid-O2 94%, O2-gas 2.08%, O2-concentrators 3.8%), with again high intra-regional variation (100/100,000 in Bergamo vs 410/100,000 in Valle Camonica). The crude rate of HMV prescriptions in Lombardy is very high, with a high intra-regional variability in prescribing HMV, LTOT and CPAP which is partly explainable by the accessibility to specialist centers with HMV/sleep-study facilities. Analysis of administrative data and variability mapping can help identify areas of reduced access for an improved standardization of services. An audit among Health Payer and prescribers to interpret the described huge variability could be welcomed.

scholarly journals Analysis of Ionospheric foF2 by Solar Activity over the Korean Peninsula

2016 ◽  
Vol 6 (1) ◽  
pp. 71
Author(s):  
Min-Ho Jeon ◽  
Chang-Heon Oh
Keyword(s):  
Solar Activity ◽  
Standard Deviation ◽  
Sea Level ◽  
Critical Frequency ◽  
High Electron ◽  
High Electron Density ◽  
Layer Height ◽  
Annual Variations ◽  
F Region ◽  
The Mean

The F2 layer is the upper sector of the ionospheric F region, and it is ~250 km above sea level. It has a high electron density and thus plays an important role in shortwave communications. The variations of the critical frequency of the F2 layer (foF2) offer clues regarding the events happening within the entire F2 layer, and foF2 analysis is essential for stable shortwave communications. This study analyzes the seasonal and annual variations of the foF2 as well as the reactions of the F2 layer height at two locations in South Korea by employing the mean and standard deviation (SD) used in previous studies. To ensure a more elaborate analysis, the median and quartiles were used for analyzing the ionosphere. We thereby compensate for the limitations of the mean and SD in developing the SD, despite the convenience of the SD for probability analysis. The application of the median and quartiles for the analysis of ionospheric data led to analysis results with greater detail. This was achieved by determining the relative SD and concurrently displaying the outliers and range of variations

Analysis of Ionospheric foF2 by Solar Activity over the Korean Peninsula

2016 ◽  
Vol 6 (1) ◽  
pp. 71
Author(s):  
Min-Ho Jeon ◽  
Chang-Heon Oh
Keyword(s):  
Solar Activity ◽  
Standard Deviation ◽  
Sea Level ◽  
Critical Frequency ◽  
High Electron ◽  
High Electron Density ◽  
Layer Height ◽  
Annual Variations ◽  
F Region ◽  
The Mean

The F2 layer is the upper sector of the ionospheric F region, and it is ~250 km above sea level. It has a high electron density and thus plays an important role in shortwave communications. The variations of the critical frequency of the F2 layer (foF2) offer clues regarding the events happening within the entire F2 layer, and foF2 analysis is essential for stable shortwave communications. This study analyzes the seasonal and annual variations of the foF2 as well as the reactions of the F2 layer height at two locations in South Korea by employing the mean and standard deviation (SD) used in previous studies. To ensure a more elaborate analysis, the median and quartiles were used for analyzing the ionosphere. We thereby compensate for the limitations of the mean and SD in developing the SD, despite the convenience of the SD for probability analysis. The application of the median and quartiles for the analysis of ionospheric data led to analysis results with greater detail. This was achieved by determining the relative SD and concurrently displaying the outliers and range of variations

scholarly journals Long-term changes in thermospheric composition inferred from a spectral analysis of ionospheric F-region data

2014 ◽  
Vol 32 (2) ◽  
pp. 113-119 ◽  
Author(s):  
C. J. Scott ◽  
R. Stamper ◽  
H. Rishbeth
Keyword(s):  
Relative Strength ◽  
Falkland Islands ◽  
Composition Change ◽  
Geomagnetic Index ◽  
F Region ◽  
Circulation Patterns ◽  
Long Term Changes ◽  
Region Data ◽  
Index Changes

Abstract. A study of ionospheric data recorded at Slough/Chilton, UK, from 1935 to 2012, has revealed long-term changes in the relative strength of the annual and semi-annual variability in the ionospheric F2 layer critical frequencies. Comparing these results with data from the southern hemisphere station at Stanley in the Falkland Islands between 1945 and 2012 reveals a trend that appears to be anti-correlated with that at Chilton. The behaviour of foF2 is a function of thermospheric composition and so we argue that the observed long-term changes are driven by composition change. The ionospheric trends share some of their larger features with the trend in the variability of the aa geomagnetic index. Changes to the semi-annual/annual ratio in the Slough/Chilton and Stanley data may therefore be attributable to the variability in geomagnetic activity which controls the average latitudinal extent of the auroral ovals and subsequent thermospheric circulation patterns. Changes in ionospheric composition or thermospheric wind patterns are known to influence the height of the F2 layer at a given location. Long-term changes to the height of the F2 layer have been used to infer an ionospheric response to greenhouse warming. We suggest that our observations may influence such measurements and since the results appear to be dependent on geomagnetic longitude, this could explain why the long-term drifts observed in F2 layer height differ between locations.

scholarly journals Photovoltaic power potential in West Africa using long-term satellite data

2020 ◽  
Vol 20 (21) ◽  
pp. 12871-12888
Author(s):  
Ina Neher ◽  
Susanne Crewell ◽  
Stefanie Meilinger ◽  
Uwe Pfeifroth ◽  
Jörg Trentmann
Keyword(s):  
West Africa ◽  
Temporal Variability ◽  
Solar Irradiance ◽  
Negative Trend ◽  
Positive Trend ◽  
Wet Season ◽  
Regional Variability ◽  
Surface Solar Radiation ◽  
Data Set

Abstract. This paper addresses long-term historical changes in solar irradiance in West Africa (3 to 20∘ N and 20∘ W to 16∘ E) and the implications for photovoltaic systems. Here, we use satellite irradiance (Surface Solar Radiation Data Set – Heliosat, Edition 2.1 – SARAH-2.1) and temperature data from a reanalysis (ERA5) to derive photovoltaic yields. Based on 35 years of data (1983–2017), the temporal and regional variability as well as long-term trends in global and direct horizontal irradiance are analyzed. Furthermore, a detailed time series analysis is undertaken at four locations. According to the high spatial resolution SARAH-2.1 data record (0.05∘×0.05∘), solar irradiance is largest (up to a 300 W m−2 daily average) in the Sahara and the Sahel zone with a positive trend (up to 5 W m−2 per decade) and a lower temporal variability (<75 W m−2 between 1983 and 2017 for daily averages). In contrast, the solar irradiance is lower in southern West Africa (between 200 W m−2 and 250 W m−2) with a negative trend (up to −5 W m−2 per decade) and a higher temporal variability (up to 150 W m−2). The positive trend in the north is mostly connected to the dry season, whereas the negative trend in the south occurs during the wet season. Both trends show 95 % significance. Photovoltaic (PV) yields show a strong meridional gradient with the lowest values of around 4 kWh  kWp−1 in southern West Africa and values of more than 5.5 kWh  kWp−1 in the Sahara and Sahel zone.

scholarly journals Demographic variability in spruce-fir-beech forest stands in Europe

2017 ◽  
Author(s):  
Guillaume Lagarrigues ◽  
Franck Jabot ◽  
Andreas Zingg ◽  
Jean-Claude Gégout ◽  
Matija Klopčič ◽  
...  
Keyword(s):  
Forest Dynamics ◽  
Abies Alba ◽  
Beech Forest ◽  
Distribution Area ◽  
Distribution Models ◽  
Regional Variability ◽  
Mixed Stands ◽  
Data Set ◽  
Demographic Processes

1AbstractMany studies have predicted large changes in forest dynamics during the next century because of global warming. Although empirical approaches and studies based on species distribution models provide valuable information about future changes, they do not take into account biotic interactions and stand-level demographic variations. The objective of this study was to quantify the local and regional variability of the growth and regeneration of three important forest species growing often in mixed stands in Europe (Picea abies (L.) Karst., Abies alba Mill., Fagus sylvatica), and to assess the climatic drivers of this variability. For that purpose, we collected a large forestry data set compiling the long-term (up to 100 years) evolution of species and size distributions for 163 stands across Europe, in the mesic distribution area of these forests. We used an inverse modeling approach, Approximate Bayesian Computation, to calibrate an individual-based model of forest dynamics on these data. Our study revealed that the variability of the demographic processes was of the same order of magnitude between stands of a same forest as between different forests. Out of the three species and two demographic processes studied, only the fir growth strongly varied with temperature. Water availability did not explain any demographic variation over stands. For these forests experiencing mesic conditions, local unmeasured factors seem therefore to have an influence at least as important as macro-environmental factors on demographic variations. Efforts to include these important factors in projection scenarios should therefore be prioritized. Besides, our study demonstrates that inverse modelling methods make possible the analysis of long-term forestry data. Such data should therefore be more widely compiled and used for ecological and global change research.

scholarly journals A PROBABILISTIC MODEL OF REGIONAL-SCALE RESPONSE TO EXTREME STORM EVENTS

2018 ◽  
pp. 46
Author(s):  
Tomas Beuzen ◽  
Kristen D. Splinter ◽  
Ian L. Turner ◽  
Mitchell D. Harley ◽  
Lucy A. Marshall ◽  
...  
Keyword(s):  
Regional Scale ◽  
Airborne Lidar ◽  
Beach Erosion ◽  
Storm Events ◽  
Regional Variability ◽  
Data Set ◽  
High Resolution Data ◽  
Extreme Storm ◽  
Lidar Measurements

Predicting beach erosion caused by extreme storms remains a key focus of the coastal engineering community, having important implications for both emergency and long-term coastal management and planning. In June 2016, an extra-tropical cyclone impacted the east coast of Australia, resulting in the largest erosion event recorded in this region for several decades. High-resolution data collected during this event included immediate pre and post-storm airborne LIDAR measurements of the subaerial beach along 400 km of coastline, as well as detailed modeling of inshore wave conditions. This unprecedented data set presents a unique opportunity to explore key drivers of the observed local and regional variability in the response of beaches to extreme storm events.

scholarly journals Long-term variability of solar irradiance and its implications for photovoltaic power in West Africa

2020 ◽  
Author(s):  
Ina Neher ◽  
Susanne Crewell ◽  
Stefanie Meilinger ◽  
Uwe Pfeifroth ◽  
Jörg Trentmann
Keyword(s):  
West Africa ◽  
Power Systems ◽  
Solar Irradiance ◽  
Positive Trend ◽  
Wet Season ◽  
Regional Variability ◽  
Surface Solar Radiation ◽  
Data Set ◽  
Photovoltaic Power

Abstract. This paper addresses long-term changes in solar irradiance for West Africa (3° N to 20° N and 20° W to 16° E) and its implications for photovoltaic power systems. Here we use satellite irradiance (Surface Solar Radiation Data Set-Heliosat, Edition 2.1, SARAH-2.1) to derive photovoltaic yields. Based on 35 years of data (1983–2017) the temporal and regional variability as well as long-term trends of global and direct horizontal irradiance are analyzed. Furthermore, at four locations a detailed time series analysis is undertaken. The dry and the wet season are considered separately. According to the high resolved SARAH-2.1 data record (0.05° x 0.05°), solar irradiance is largest (with up to 300 W/m² daily average) in the Sahara and the Sahel zone with a positive trend (up to 5 W/m²/decade) and a lower variability (

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