scholarly journals Comparison of ground-based and satellite data on spatiotemporal distribution of lightning discharges under solar minimum

2021 ◽  
Vol 7 (4) ◽  
pp. 111-119
Author(s):  
Valery Denisenko ◽  
Andrey Lyakhov
Keyword(s):  
Satellite Data ◽  
Electric Circuit ◽  
Mean Value ◽  
Summer Hemisphere ◽  
Solar Local Time ◽  
Different Seasons ◽  
Lightning Discharges ◽  
Order Of Magnitude ◽  
Processing Techniques ◽  
Imaging Sensor

Worldwide maps of lightning activity have been obtained from the ground-based World Wide Lightning Location Network (WWLLN) for 2007–2009. We have compiled these maps separately for different seasons and UT periods, using WWLLN data on the time and coordinates of each of the recorded lightning. The total number of flashes of lightning in WWLLN data is by an order of magnitude smaller than in satellite data from Optical Transient Detector and the Lightning Imaging Sensor satellites. However, the key features of the spatial distribution and seasonal trends coincide well. The main difference observed is the absence of diurnal variation (similar to Carnegie curve) in WWLLN data against the satellite one. This concerns the global lightning number as well as its density in major thunderstorm regions. The solar local time dependence is also weak in WWLLN data. We show that in 2007–2009 the mean latitude of lightning observation is shifted to the summer hemisphere up to 10° from the annual mean value. From the beginning of 2007 to the end of 2009, the global monthly average number of flashes of lightning increased threefold. We attribute this fact primarily to improved processing techniques in WWLLN. The constructed maps are necessary for numerical simulation of the Global Electric Circuit.

scholarly journals Comparison of ground-based and satellite data on spatiotemporal distribution of lightning discharges under solar minimum

2021 ◽  
Vol 7 (4) ◽  
pp. 104-112
Author(s):  
Valery Denisenko ◽  
Andrey Lyakhov
Keyword(s):  
Satellite Data ◽  
Electric Circuit ◽  
Mean Value ◽  
Summer Hemisphere ◽  
Solar Local Time ◽  
Different Seasons ◽  
Lightning Discharges ◽  
Order Of Magnitude ◽  
Processing Techniques ◽  
Imaging Sensor

Worldwide maps of lightning activity have been obtained from the ground-based World Wide Lightning Location Network (WWLLN) for 2007–2009. We have compiled these maps separately for different seasons and UT periods, using WWLLN data on the time and coordinates of each of the recorded lightning. The total number of flashes of lightning in WWLLN data is by an order of magnitude smaller than in satellite data from Optical Transient Detector and the Lightning Imaging Sensor satellites. However, the key features of the spatial distribution and seasonal trends coincide well. The main difference observed is the absence of diurnal variation (similar to Carnegie curve) in WWLLN data against the satellite one. This concerns the global lightning number as well as its density in major thunderstorm regions. The solar local time dependence is also weak in WWLLN data. We show that in 2007–2009 the mean latitude of lightning observation is shifted to the summer hemisphere up to 10° from the annual mean value. From the beginning of 2007 to the end of 2009, the global monthly average number of flashes of lightning increased threefold. We attribute this fact primarily to improved processing techniques in WWLLN. The constructed maps are necessary for numerical simulation of the Global Electric Circuit.

scholarly journals Stable Carbon and Sulfur Isotope Characteristics of Stream Water in a Typical Karst Small Catchment, Southwest China

Water ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 523
Author(s):  
Yang Tang ◽  
Ruiyin Han
Keyword(s):  
Water Samples ◽  
Chemical Weathering ◽  
Stream Water ◽  
Mean Value ◽  
Small Catchment ◽  
Temperature And Precipitation ◽  
Δ13c Value ◽  
Different Seasons ◽  
Sources Of Solutes ◽  
Surface Water Samples

Surface water samples from the Maolan National Natural Reserved Park (MNNRP) were analyzed from Sept. 2013 to June 2014, for major ion concentrations (K+, Na+, Ca2+, Mg2+, Cl−, SO42−, HCO3−), δ13C-DIC and δ34S-SO42− to quantify the sources of solutes and chemical weathering. The results show that HCO3− and SO42− are the main anions in Banzhai watershed, which account for 86.2 and 10.4% of the total anion equivalent, respectively. While Ca2+ and Mg2+ account for 76.9 and 20.5%, respectively. Considerable Mg2+ in stream water indicates that it may be affected by dolomite weathering. stream water samples present the δ13C-DIC values in the range of −16.9‰~−10.8‰ (mean value was −13.9‰), which were lower than that of the groundwater. The δ34S-SO42− values ranged from −15.2‰ to 1.7‰ (mean value was −4.4‰). There was a negative correlation between HCO3− content and δ13C value, implying the result of the interaction of temperature and precipitation intensity in different seasons. The significant positive correlation between SO42− content and δ13C-DIC indicates that H2SO4 may be involved in the weathering process of carbonate rocks in small watershed scale. The content of SO42− in a school sample site was much higher than that of other sample sites for the interference from human sources. The δ34S values show that the average δ34S-SO42− in most sites is close to the δ34S isotopic values of Guizhou coal and rain, indicating that they may be affected by local coal.

Stable Isotopes Analysis of Precipitation in Subtropical Plateau of Yunnan

2014 ◽  
Vol 1010-1012 ◽  
pp. 1059-1063
Author(s):  
Wei Guan ◽  
Tao Fan ◽  
Xiu Qin Zhu
Keyword(s):  
Stable Isotopes ◽  
Rainy Season ◽  
Mean Value ◽  
Dry Season ◽  
Precipitation Line ◽  
Stable Isotopic ◽  
Different Seasons ◽  
Geographical Position ◽  
The Mean ◽  
The Relationship

To elucidate the relationship between stable isotopes of precipitation (SIP) and the extreme drought in Kunming area, based on the stable isotopes data of the GNIP in Kunming site from 1986 to 2003, the precipitation line equation is brought forward and the seasonal change rule of stable isotopes are discussed. The stable isotopic compositions of precipitation exhibit great diversities in different seasons during to influences of multiple factors, such as monsoon, rainfall amount moisture source and others. The δ18O values in rainwater exhibit significant seasonal variations, the average of-10.12‰ in rainy season, the dry season is-4.5‰, having lower values in the rainy season and higher one in the dry season. The amount effect of precipitation is very distinct, that concealed the temperature effect. Got the special geographical position,dvalues present unique characteristics, the average ofdvalues is 10.78‰ in rainy season, and is 4.86‰ in dry season, the mean value is generally lower than most parts of the world.

Making seismic monitoring work in a complex desert environment — 4D processing

2019 ◽  
Vol 38 (8) ◽  
pp. 637-645 ◽  
Author(s):  
Robert Smith ◽  
Emad Hemyari ◽  
Andrey Bakulin ◽  
Abdullah Alramadhan
Keyword(s):  
Survey Design ◽  
Signal To Noise Ratio ◽  
Time Lapse ◽  
Seismic Monitoring ◽  
Carbonate Reservoir ◽  
Acquisition System ◽  
Desert Environment ◽  
Near Surface ◽  
Different Seasons ◽  
Processing Techniques

Seismic monitoring of an onshore carbonate reservoir in a desert environment has been achieved for the first time. Optimizing data repeatability was key to detecting the weak 4D (time-lapse) signal resulting from a fluid-injection program, which was achieved through a combination of specialized survey design, careful acquisition, and dedicated 4D processing. The hybrid acquisition system utilized buried geophones, which significantly reduced 4D noise caused by variability in the near-surface environment. Despite the extensive acquisition efforts, time-lapse processing is an essential component of achieving highly repeatable data. A fit-for-purpose workflow was developed to reduce the remaining 4D noise using a combination of parallel and simultaneous processing. Processing steps leading to the largest improvement in reflection signal-to-noise ratio, such as noise attenuation, amplitude balancing, and supergrouping, produced the largest reduction in 4D noise. Outstanding final migrated data repeatability has been achieved, comparable to levels reported for the more favorable permanent marine systems. However, the need to use surface sources results in a seasonal imprint on data repeatability, which hinders the interpretation of surveys acquired during different seasons. In the absence of a fully buried acquisition system, advanced processing techniques such as surface-consistent matching filters may be required to resolve these variations.

Survey design for multicomponent electromagnetic systems

Geophysics ◽  
1984 ◽  
Vol 49 (3) ◽  
pp. 265-273 ◽  
Author(s):  
James C. Macnae
Keyword(s):  
Potential Field ◽  
Survey Design ◽  
Time Derivative ◽  
Vertical Component ◽  
Noise Amplitude ◽  
Worldwide Distribution ◽  
Spatial Sense ◽  
Spatial Coverage ◽  
Lightning Discharges ◽  
Order Of Magnitude

A roving coil receiver is employed by several modern EM exploration systems to measure various spatial components of the time derivative of the magnetic field set up by a fixed transmitter. The absolute instantaneous secondary field measured above the surface of the earth is a potential field in this case, and, using well‐established potential field theory, it is known to be possible to predict the response of both horizontal components on any plane from a complete knowledge of the vertical component on the same plane. The required operation is simply performed in the wavenumber domain and is an amplitude invariant quadrature phase translation. In practice, errors are introduced in this transformation by spatial aliasing effects which depend upon the sampling density and by windowing effects which depend upon the areal extent of data coverage. The major source of noise in EM survey data collected in remote areas is sferic activity, which arises from the worldwide distribution of lightning discharges. Sferic noise, although time‐varying, is predominantly uniform in a spatial sense, with local spatially varying anomalies near conductive inhomogeneities. Since the horizontal component noise amplitude is typically an order of magnitude greater than the vertical component noise amplitude, a strong case can be made that it is advantageous in routine surveys to increase the spatial coverage of vertical component data rather than to read both horizontal components.

20 years of forest change in Natura 2000 protected areas network

2020 ◽  
Author(s):  
Marinela-Adriana Chețan ◽  
Andrei Dornik
Keyword(s):  
Protected Areas ◽  
Satellite Data ◽  
Forest Cover ◽  
Natura 2000 ◽  
Temporal Analysis ◽  
Mean Value ◽  
Google Earth ◽  
Forest Change ◽  
Forest Protection ◽  
Forest Area Change

<p>Natura 2000 network, the world's largest network of protected areas, is considered a success for habitat and biodiversity protection, in the last decades. Our objective is to develop an algorithm for satellite data temporal analysis of protected areas, and to apply subsequently this algorithm for analysis of all Natura 2000 sites in Europe. We have developed an algorithm for satellite data temporal analysis of protected areas using JavaScript in Google Earth Engine, which is a web interface for the massive analysis of geospatial data, providing access to huge amount of data and facilitating development of complex workflows. This work focused on analysis of Global Forest Change dataset representing forest change, at 30 meters resolution, globally, between 2000 and 2018. Our results show that at least regarding forest protection, the network is not very successful, the 25350 sites losing 35246.8 km<sup>2</sup> of forest cover between 2000 and 2018, gaining only 9862.1 km<sup>2</sup>. All 28 countries recorded a negative forest net change, with a mean value of -906.6 km<sup>2</sup>, the largest forest area change recording Spain (-5106.4 km<sup>2</sup> in 1631 sites), Poland (-4529 km<sup>2</sup> in 962 sites), Portugal (-2781.9 km<sup>2</sup> in 120 sites), Romania (-1601.4 km<sup>2</sup> in 569 sites), Germany (-1365.7 km<sup>2</sup> in 5049 sites) and France (-1270.9 km<sup>2</sup> in 1520 sites). Among countries with the lowest values in net forest change is Ireland (-17.4 km<sup>2</sup> in 447 sites), Estonia (-104.1 km<sup>2</sup> in 518 sites), Netherlands (-132.3 km<sup>2</sup> in 152 sites), Finland (-268.6 km<sup>2</sup> in 1722 sites) and Sweden (-341.6 km<sup>2</sup> in 3786 sites).</p>

Liquid helium films. I. The thickness of the film

1950 ◽  
Vol 203 (1072) ◽  
pp. 119-132 ◽  
Keyword(s):  
Liquid Helium ◽  
Dynamic Method ◽  
Mean Value ◽  
Helium Films ◽  
Helium Ii ◽  
Experimental Factor ◽  
Order Of Magnitude ◽  
The Mean

The thickness ( d ) of the helium II film and its variation with height ( H ) and temperature were measured by a dynamic method involving the oscillations of a meniscus in a capillary. The variation with height could be represented only approximately by the equation d = k/H n , as the effective value of n was greater at smaller values of H . The mean value of n over a range of heights from 0·5 to 5 cm. was 0·14, which is appreciably smaller than the values predicted by the theories so far advanced to explain the formation of the film. The order of magnitude of k was 2 x 10 -6 cm., but it varied slightly with the nature of the surface or some other experimental factor.

scholarly journals Relativistic electron beams above thunderclouds

2011 ◽  
Vol 11 (5) ◽  
pp. 15551-15572
Author(s):  
M. Füllekrug ◽  
R. Roussel-Dupré ◽  
E. M. D. Symbalisty ◽  
J. J. Colman ◽  
O. Chanrion ◽  
...  
Keyword(s):  
Electron Beam ◽  
Relativistic Electron ◽  
Electron Beams ◽  
Low Frequency ◽  
Electric Circuit ◽  
Total Charge ◽  
Relativistic Electron Beams ◽  
Radio Signals ◽  
Lightning Discharges ◽  
Cloud To Ground Lightning

Abstract. Non-luminous relativistic electron beams above thunderclouds are detected by radio remote sensing with low frequency radio signals from 40–400 kHz. The electron beams occur 2–9 ms after positive cloud-to-ground lightning discharges at heights between 22–72 km above thunderclouds. The positive lightning discharges also cause sprites which occur either above or before the electron beam. One electron beam was detected without any luminous sprite occurrence which suggests that electron beams may also occur independently. Numerical simulations show that the beamed electrons partially discharge the lightning electric field above thunderclouds and thereby gain a mean energy of 7 MeV to transport a total charge of 10 mC upwards. The impulsive current associated with relativistic electron beams above thunderclouds is directed downwards and needs to be considered as a novel element of the global atmospheric electric circuit.

scholarly journals On the Accuracy of Error Propagation Calculations by Analytic Formulas Obtained for the Inverse Transformation

2019 ◽  
Vol 64 (3) ◽  
pp. 217
Author(s):  
V. I. Romanenko ◽  
N. V. Kornilovska
Keyword(s):  
Error Propagation ◽  
Random Variable ◽  
Mean Value ◽  
Inverse Transformation ◽  
First Order ◽  
Order Of Magnitude ◽  
The Mean ◽  
Normally Distributed

The accuracy of error propagation calculations is estimated for the transformation x → y = f(x) of the normally distributed random variable x. The estimation is based on the formulas for the error propagation obtained for the inverse transformation y → x of the normally distributed random variable y. In the general case, the calculation accuracy for the mean value and the variance of the random variable y is shown to be of the first order of magnitude in the variance of the random variable x.

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