Long-Term Changes in Ionospheric Climate in Terms of foF2

There is not only space weather; there is also space climate. Space climate includes the ionospheric climate, which is affected by long-term trends in the ionosphere. One of the most important ionospheric parameters is the critical frequency of the ionospheric F2 layer, foF2, which corresponds to the maximum ionospheric electron density, NmF2. Observational data series of foF2 have been collected at some stations for as long as over 60 years and continents are relatively well covered by a network of ionosondes, instruments that measure, among others, foF2. Trends in foF2 are relatively weak. The main global driver of long-term trends in foF2 is the increasing concentration of greenhouse gases, namely CO2, in the atmosphere. The impact of the other important trend driver, the secular change in the Earth’s main magnetic field, is very regional, being positive in some regions, negative in others, and neither in the rest. There are various sources of uncertainty in foF2 trends. One is the inhomogeneity of long foF2 data series. The main driver of year-to-year changes in foF2 is the quasi-eleven-year solar cycle. The removal of its effect is another source of uncertainty. Different methods might provide somewhat different strengths among trends in foF2. All this is briefly reviewed in the paper.

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Solute transport dynamics in small, shallow groundwater-dominated agricultural catchments: insights from a high-frequency, multisolute 10 yr-long monitoring study

Hydrology and Earth System Sciences ◽

10.5194/hess-17-1379-2013 ◽

2013 ◽

Vol 17 (4) ◽

pp. 1379-1391 ◽

Cited By ~ 54

Author(s):

A. H. Aubert ◽

C. Gascuel-Odoux ◽

G. Gruau ◽

N. Akkal ◽

M. Faucheux ◽

...

Keyword(s):

High Frequency ◽

Inorganic Carbon ◽

Shallow Groundwater ◽

Data Series ◽

Wet Season ◽

Transport Dynamics ◽

Agricultural Catchments ◽

Organic And Inorganic Carbon ◽

The Impact

Abstract. High-frequency, long-term and multisolute measurements are required to assess the impact of human pressures on water quality due to (i) the high temporal and spatial variability of climate and human activity and (ii) the fact that chemical solutes combine short- and long-term dynamics. Such data series are scarce. This study, based on an original and unpublished time series from the Kervidy-Naizin headwater catchment (Brittany, France), aims to determine solute transfer processes and dynamics that characterise this strongly human-impacted catchment. The Kervidy-Naizin catchment is a temperate, intensive agricultural catchment, hydrologically controlled by shallow groundwater. Over 10 yr, five solutes (nitrate, sulphate, chloride, and dissolved organic and inorganic carbon) were monitored daily at the catchment outlet and roughly every four months in the shallow groundwater. The concentrations of all five solutes showed seasonal variations but the patterns of the variations differed from one solute to another. Nitrate and chloride exhibit rather smooth variations. In contrast, sulphate as well as organic and inorganic carbon is dominated by flood flushes. The observed nitrate and chloride patterns are typical of an intensive agricultural catchment hydrologically controlled by shallow groundwater. Nitrate and chloride originating mainly from organic fertilisers accumulated over several years in the shallow groundwater. They are seasonally exported when upland groundwater connects with the stream during the wet season. Conversely, sulphate as well as organic and inorganic carbon patterns are not specific to agricultural catchments. These solutes do not come from fertilisers and do not accumulate in soil or shallow groundwater; instead, they are biogeochemically produced in the catchment. The results allowed development of a generic classification system based on the specific temporal patterns and source locations of each solute. It also considers the stocking period and the dominant process that limits transport to the stream, i.e. the connectivity of the stocking compartment. This mechanistic classification can be applied to any chemical solute to help assess its origin, storage or production location and transfer mechanism in similar catchments.

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Investigations of long-term trends in the ionosphere with world-wide ionosonde observations*

Advances in Radio Science ◽

10.5194/ars-2-253-2004 ◽

2005 ◽

Vol 2 ◽

pp. 253-258 ◽

Cited By ~ 10

Author(s):

J. Bremer

Keyword(s):

Data Series ◽

Model Calculations ◽

Maximum Electron Density ◽

Model Predictions ◽

Density Values ◽

Long Term Trends ◽

Experimental Values ◽

The Individual ◽

Global Mean

Abstract. Basing on model calculations by Roble and Dickinson (1989) for an increasing content of atmospheric greenhouse gases in the Earth’s atmosphere Rishbeth (1990) predicted a lowering of the ionospheric F2- and E-regions. Later Rishbeth and Roble (1992) also predicted characteristic longterm changes of the maximum electron density values of the ionospheric E-, F1-, and F2-layers. Long-term observations at more than 100 ionosonde stations have been analyzed to test these model predictions. In the E- and F1-layers the derived experimental results agree reasonably with the model trends (lowering of h'E and increase of ƒoE and ƒoF1, in the E-layer the experimental values are however markedly stronger than the model data). In the ionospheric F2-region the variability of the trends derived at the different individual stations for hmF2 as well as ƒoF2 values is too large to estimate reasonable global mean trends. The reason of the large differences between the individual trends is not quite clear. Strong dynamical effects may play an important role in the F2-region. But also inhomogeneous data series due to technical changes as well as changes in the evaluation algorithms used during the long observation periods may influence the trend analyses.

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The impact of non-ideality on reconstructing spatial and temporal variations of aerosol acidity with multiphase buffer theory

10.5194/egusphere-egu21-9292 ◽

2021 ◽

Author(s):

Yafang Cheng ◽

Guangjie Zheng ◽

Hang Su ◽

Siwen Wang ◽

Andrea Pozzer

Keyword(s):

Molar Fraction ◽

Temporal Variations ◽

Spatial Variations ◽

Acid Dissociation ◽

Acid Dissociation Constant ◽

Aerosol Acidity ◽

Long Term Trends ◽

Factor C ◽

The Impact

Aerosol acidity is a key parameter in atmospheric aqueous chemistry and strongly influence the interactions of air pollutants and ecosystem. The recently proposed multiphase buffer theory provides a framework to reconstruct long-term trends and spatial variations of aerosol pH based on the effective acid dissociation constant of ammonia (Ka,NH3*). However, non-ideality in aerosol droplets is a major challenge limiting its broad applications. Here, we introduced a non-ideality correction factor (cni) and investigated its governing factors. We found that besides relative humidity (RH) and temperature, cni is mainly determined by the molar fraction of NO3- in aqueous-phase anions, due to different NH4+ activity coefficients between (NH4)2SO4- and NH4NO3-dominated aerosols. A parameterization method is thus proposed to estimate cni at given RH, temperature and NO3- fraction, and is validated against long-term observations and global simulations. In the ammonia-buffered regime, with cni correction the buffer theory can well reproduce the Ka,NH3* predicted by comprehensive thermodynamic models, with root-mean-square deviation ~0.1 and correlation coefficient ~1. Note that, while cni is needed to predict Ka,NH3* levels, it is usually not the dominant contributor to its variations, as ~90% of the temporal or spatial variations in Ka,NH3* is due to variations in aerosol water and temperature.

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Long-Term Trends in the Critical Frequency of the E-layer

Geomagnetism and Aeronomy ◽

10.1134/s0016793218030052 ◽

2018 ◽

Vol 58 (3) ◽

pp. 338-347 ◽

Cited By ~ 2

Author(s):

A. D. Danilov ◽

A. V. Konstantinova

Keyword(s):

Critical Frequency ◽

Long Term Trends

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Evaluating the impact of ballast undercutting on the roughness of track geometry over different subgrade conditions

Proceedings of the Institution of Mechanical Engineers Part F Journal of Rail and Rapid Transit ◽

10.1177/0954409717720347 ◽

2017 ◽

Vol 232 (5) ◽

pp. 1266-1276

Author(s):

Kirk M Scanlan ◽

Michael T Hendry ◽

C Derek Martin

Keyword(s):

Surface Roughness ◽

Organic Soils ◽

Western Canada ◽

Railway Ballast ◽

Track Geometry ◽

Track Maintenance ◽

Heavy Haul ◽

Long Term Trends ◽

The Impact

The progressive degradation of railway ballast is often cited as a primary factor that contributes to the development of track roughness, while ballast renewal (undercutting) attempts to manage its long-term development. Soft subgrades have been shown to strongly influence track geometry and are a contributing factor that has not been considered during conventional track maintenance. This study evaluated the impact of undercutting on long-term trends in track geometry roughness, and what impact softer subgrades had on the effectiveness of undercutting. A combined 6.90 km of Class II–IV heavy-haul track in Western Canada (undercut in 2010 and 2011) formed the basis for this analysis. Annual traffic on these sections typically totals 50 million gross tonnes. Long-term trends in the track crosslevel, alignment, and surface roughness after ballast renewal were derived from 50 track geometry surveys carried out over a five-year period (2010–2015). The results showed that undercutting significantly reduced track roughness over sand, silt, clay, or till subgrades; however, it was often ineffective when used over soft organic subgrades. Thus, while ballast degradation is the primary cause of track roughness in segments constructed on mineral subgrades, it is not a mechanism that results in track geometry roughness over soft organic soils.

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The Impact of Improved Thermistor Calibration on the Expendable Bathythermograph Profile Data

Journal of Atmospheric and Oceanic Technology ◽

10.1175/jtech-d-17-0024.1 ◽

2017 ◽

Vol 34 (9) ◽

pp. 1947-1961 ◽

Cited By ~ 2

Author(s):

Marlos Goes ◽

Elizabeth Babcock ◽

Francis Bringas ◽

Peter Ortner ◽

Gustavo Goni

Keyword(s):

Small Sample Size ◽

Heat Content ◽

Small Sample ◽

Profile Data ◽

Expendable Bathythermograph ◽

Different Types ◽

Long Term Trends ◽

The Mean ◽

The Impact

AbstractExpendable bathythermograph (XBT) data provide one of the longest available records of upper-ocean temperature. However, temperature and depth biases in XBT data adversely affect estimates of long-term trends of ocean heat content and, to a lesser extent, estimates of volume and heat transport in the ocean. Several corrections have been proposed to overcome historical biases in XBT data, which rely on constantly monitoring these biases. This paper provides an analysis of data collected during three recent hydrographic cruises that utilized different types of probes, and examines methods to reduce temperature and depth biases by improving the thermistor calibration and reducing the mass variability of the XBT probes.The results obtained show that the use of individual thermistor calibration in XBT probes is the most effective calibration to decrease the thermal bias, improving the mean thermal bias to less than 0.02°C and its tolerance from 0.1° to 0.03°C. The temperature variance of probes with screened thermistors is significantly reduced by approximately 60% in comparison to standard probes. On the other hand, probes with a tighter weight tolerance did not show statistically significant reductions in the spread of depth biases, possibly because of the small sample size or the sensitivity of the depth accuracy to other causes affecting the analysis.

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Long-term trends in the ionospheric E and F1 regions

Annales Geophysicae ◽

10.5194/angeo-26-1189-2008 ◽

2008 ◽

Vol 26 (5) ◽

pp. 1189-1197 ◽

Cited By ~ 46

Author(s):

J. Bremer

Keyword(s):

Geomagnetic Latitude ◽

Data Series ◽

General Behaviour ◽

Global Trends ◽

Evaluation Algorithm ◽

Ozone Trend ◽

E Region ◽

Long Term Trends ◽

Source Of Information

Abstract. Ground based ionosonde measurements are the most essential source of information about long-term variations in the ionospheric E and F1 regions. Data of such observations have been derived at many different ionospheric stations all over the world some for more than 50 years. The standard parameters foE, h'E, and foF1 are used for trend analyses in this paper. Two main problems have to be considered in these analyses. Firstly, the data series have to be homogeneous, i.e. the observations should not be disturbed by artificial steps due to technical reasons or changes in the evaluation algorithm. Secondly, the strong solar and geomagnetic influences upon the ionospheric data have carefully to be removed by an appropriate regression analysis. Otherwise the small trends in the different ionospheric parameters cannot be detected. The trends derived at individual stations differ markedly, however their dependence on geographic or geomagnetic latitude is only small. Nevertheless, the mean global trends estimated from the trends at the different stations show some general behaviour (positive trends in foE and foF1, negative trend in h'E) which can at least qualitatively be explained by an increasing atmospheric greenhouse effect (increase of CO2 content and other greenhouse gases) and decreasing ozone values. The positive foE trend is also in qualitative agreement with rocket mass spectrometer observations of ion densities in the E region. First indications could be found that the changing ozone trend at mid-latitudes (before about 1979, between 1979 until 1995, and after about 1995) modifies the estimated mean foE trend.

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The Impact of Non-uniform Sampling on Stratospheric Ozone Trends Derived from Occultation Instruments

10.5194/acp-2017-575 ◽

2017 ◽

Author(s):

Robert P. Damadeo ◽

Joseph M. Zawodny ◽

Ellis E. Remsberg ◽

Kaley A. Walker

Keyword(s):

Stratospheric Ozone ◽

Primary Source ◽

Data Sets ◽

Sampled Data ◽

Uniform Sampling ◽

Ozone Trends ◽

Long Term Trends ◽

Non Uniform Sampling ◽

The Impact

Abstract. This paper applies a recently developed technique for deriving long-term trends in ozone from sparsely sampled data sets to multiple occultation instruments simultaneously without the need for homogenization. The technique can compensate for the non-uniform temporal, spatial, and diurnal sampling of the different instruments and can also be used to account for biases and drifts between instruments. These problems have been noted in recent international assessments as being a primary source of uncertainty that clouds the significance of derived trends. Results show potential recovery trends of ~ 2–3 %/decade in the upper stratosphere at mid-latitudes, which are similar to other studies, and also how sampling biases present in these data sets can create differences in derived "recovery" trends of up to ~ 1 %/decade if not properly accounted for. Limitations inherent to all techniques (e.g., relative instrument drifts) and their impacts (e.g., trend differences up to ~ 2 %/decade) are also described and a potential path forward towards resolution is presented.

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Investigation of the impact of the project office on the socio-economic development of the municipality

Vestnik of Samara University. Economics and Management ◽

10.18287/2542-0461-2021-12-1-157-172 ◽

2021 ◽

Vol 12 (1) ◽

pp. 157-172

Author(s):

Alla Yu. Trusova ◽

Vladimir I. Aksenov

Keyword(s):

Economic Development ◽

Development Strategy ◽

Scientific Article ◽

Management Tools ◽

Project Approach ◽

Regional Development Strategy ◽

Socio Economic Development ◽

Long Term Trends ◽

The Impact

The complexity of the socio-economic situation at all levels requires a detailed study of the regional development strategy issues and monitoring the implementation of presidential and government decrees. Various approaches to management were considered, for example, the national projects development implementation issues. National projecting, as a new tool for implementing state concepts, is an effective management method. The set of the project office functions provides control over the implementation of national projects at the level of development of municipalities of the Russian Federation. Historically, the level of socio-economic development of the territory has been measured and is measured using the identification of long-term trends in the development of key socio-economic indicators. The article presents a methodology that allows you to evaluate the effectiveness of project management tools since based on the results of its assessment, you can make informed management decisions and judge the effectiveness of the work of local authorities. Therefore, the aim of the scientific article was to develop an effective methodology that allows us to evaluate the effectiveness of the project office functions implemented in the management of the socio-economic development of the municipality. As a result of the study, systemic relationships were revealed of the impact of the project office on the indicators of the socio-economic development of the municipality, which was presented in the work as an important aspect of the study, the significance of which is due to the priorities of sustainable, balanced, competitive, integrated development of the Russian regions. In connection with the socio-economic policy pursued by the state, which requires speedy acceleration of the socio-economic development of municipalities, the effectiveness of the result of the application of the project approach in the municipal authorities was studied in detail.

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Analysis of Trends in the FireCCI Global Long Term Burned Area Product (1982–2018)

Fire ◽

10.3390/fire4040074 ◽

2021 ◽

Vol 4 (4) ◽

pp. 74

Author(s):

Gonzalo Otón ◽

José Miguel C. Pereira ◽

João M. N. Silva ◽

Emilio Chuvieco

Keyword(s):

Time Series ◽

Temporal Trends ◽

European Space Agency ◽

Eastern Africa ◽

Burned Area ◽

Data Series ◽

Short Term ◽

The Impact ◽

Term Data

We present an analysis of the spatio-temporal trends derived from long-term burned area (BA) data series. Two global BA products were included in our analysis, the FireCCI51 (2001–2019) and the FireCCILT11 (1982–2018) datasets. The former was generated from Moderate Resolution Imaging Spectroradiometer (MODIS) 250 m reflectance data, guided by 1 km active fires. The FireCCILT11 dataset was generated from Land Long-Term Data Record data (0.05°), which provides a consistent time series for Advanced Very High Resolution Radiometer images, acquired from the NOAA satellite series. FireCCILT11 is the longest time series of a BA product currently available, making it possible to carry out temporal analysis of long-term trends. Both products were developed under the FireCCI project of the European Space Agency. The two datasets were pre-processed to correct for temporal autocorrelation. Unburnable areas were removed and the lack of the FireCCILT11 data in 1994 was examined to evaluate the impact of this gap on the BA trends. An analysis and comparison between the two BA products was performed using a contextual approach. Results of the contextual Mann-Kendall analysis identified significant trends in both datasets, with very different regional values. The long-term series presented larger clusters than the short-term ones. Africa displayed significant decreasing trends in the short-term, and increasing trends in the long-term data series, except in the east. In the long-term series, Eastern Africa, boreal regions, Central Asia and South Australia showed large BA decrease clusters, and Western and Central Africa, South America, USA and North Australia presented BA increase clusters.

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