scholarly journals Monitoring geomagnetic information in the territory of Croatia

Geofizika ◽  
2019 ◽  
Vol 36 (1) ◽  
pp. 1-15
Author(s):  
Mario Brkić
Keyword(s):  
Annual Variation ◽  
Original Data ◽  
Time Span ◽  
Series Length ◽  
Annual Variations ◽  
Repeat Station ◽  
Observatory Data ◽  
Model Reliability ◽  
Processing Steps ◽  
Extrapolation Error

In orientation and navigation using compass, reliable map’s marginal information of Earth’s magnetic field declination and its annual variation, namely geomagnetic information (GI), is crucial. Monitoring geomagnetic information means observing declination and its annual variation and checking the reliability of the actual GI model. A typical way of monitoring GI across a national territory involves conducting periodic geomagnetic network surveys to assess and update the model. The objective of the paper was to investigate improving the GI model reliability when an earlier model’s error was raised to standard accuracy, and repeat station network surveys were not yet completed. A series of processing steps in modelling were revised to preserve the original data reliability. The partial 2008.5, 2009.5 and 2010.5 declination solutions were directly reduced to epoch 2015.0, and then to 2016.0, using the IGRF-12 model. The next step was to use 2016 and 2017 quiet daily declination means to estimate corresponding annual variations at surrounding observatories and repeat stations. Normal declination annual variation models were then built for further reductions to epoch 2017.0, and 2018.0, and for forward extrapolations. The quiet days observatory data were analysed to estimate the effect of the input time series length and linear extrapolated time span on forward extrapolation error. Thus, the reliability decline of the initial GI model slowed down in the sequence of models presented. The final GI2018v2 model, valid for 2018.0–2019.0, proved reliable in comparison to the repeat station declination observations of 2018.

scholarly journals Diurnal, Seasonal and Annual Variation of Microwave Radio Refractivity Gradient over Akure, South West Nigeria

2019 ◽  
pp. 1-11
Author(s):  
Adekunle Titus Adediji ◽  
Joseph Babatunde Dada ◽  
Moses Oludare Ajewole
Keyword(s):  
Rainy Season ◽  
Annual Variation ◽  
Ground Surface ◽  
Local Effect ◽  
Dry Season ◽  
Radio Link ◽  
Wet Season ◽  
Annual Variations ◽  
Microwave Radio

In this study, four years in-situ measurements of atmospheric parameters (pressure, temperature and relative humidity) were carried out. The measurement was by placing an automatic weather station at five different heights: ground surface, 50, 100, 150 and 200 m respectively on a 220 m Nigeria Television Authority TV tower in Akure, South Western Nigeria. The four years Data collected (January 2007 to December 2009 and January to December 2011) were used to compute radio refractivity and its gradient. The local effect of a location/ region cannot but looked into when designing effective radio link, hence the diurnal, seasonal and annual variations of the radio refractivity gradient were studied. Results showed that refractivity gradient steadily increases inthe hour of 8:30 and 9:30 to 18:00 during dry season throughout the years investigated, and decreases two hours in the rainy season than the dry season. The record shows that at 50 m altitude, the maximum and minimum values are 158 N-unit/km around 14:30 and - 286 N-unit/km around 13:30 to 14:00 hrs, LT during the dry and rainy season respectively. Seasonally, refractivity gradient is steeper with greater variability in the dry season months than in the wet season months.

Annual Variations of 14C Concentration in the Tree Rings in the Vicinity of Ignalina Nuclear Power Plant

Radiocarbon ◽  
2018 ◽  
Vol 60 (4) ◽  
pp. 1227-1236 ◽  
Author(s):  
Žilvinas Ežerinskis ◽  
Justina Šapolaitė ◽  
Algirdas Pabedinskas ◽  
Laurynas Juodis ◽  
Andrius Garbaras ◽  
...  
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Tree Rings ◽  
Environmental Samples ◽  
Nuclear Power ◽  
Time Span ◽  
Annual Variations ◽  
Pine Tree ◽  
Accelerator Mass Spectrometer ◽  
Concentration Changes

ABSTRACTIn this paper we analyze the radiocarbon (14C) concentration changes over the whole operational period of the Ignalina Nuclear Power Plant (INPP) including the post-shutdown decommissioning. Environmental samples from the vicinity of the INPP and a rural area as background of pine tree rings were analyzed with the single stage accelerator mass spectrometer (SSAMS). The analysis shows the local influence of the INPP from 3 to 7 pMC. The whole time span from 1983 to 2015 is divided into three periods representing the early and late operational and post-shutdown stages of the INPP with different 14C profiles in analyzed samples. The influence of the maintenance of the INPP and radioactive waste management activities are indicated and discussed.

Annual variations in reproductive characteristics of painted turtles (Chrysemys picta)

1986 ◽  
Vol 64 (5) ◽  
pp. 1148-1151 ◽  
Author(s):  
Lin Schwarzkopf ◽  
Ronald J. Brooks
Keyword(s):  
Body Size ◽  
Clutch Size ◽  
Repeated Measures ◽  
Egg Size ◽  
Annual Variation ◽  
Egg Mass ◽  
Annual Variations ◽  
Painted Turtles ◽  
Sources Of Variation ◽  
Clutch Mass

In Algonquin Park, Ontario, body size and clutch characteristics were recorded for 51 female painted turtles (Chrysemyspicta) in 1983, 61 in 1984, and 24 in 1985. Clutch size, clutch mass, and egg width correlated significantly with body size (carapace length) in all 3 years. Egg length and egg mass were significantly related to body size in 1984 and 1985, but not in 1983. There were no significant correlations of egg width or egg mass to clutch size. For a group of the same individuals compared by repeated-measures ANOVA, mean clutch mass and mean egg size, but not mean clutch size, varied significantly among years. Correlation of egg size with body size, lack of correlation between egg size and clutch size, and annual variation in egg size, but not clutch size, all fail to support current versions of optimal egg size theory. Twenty-six females nested in both 1983 and 1984 and 11 females nested in both 1984 and 1985. Fourteen females nested twice in 1 year: six in 1983 and eight in 1984. Between 43 and 73% of adult females nested in a given year and 12–13% nested twice in a single season. These estimates are similar to those reported for other populations of this species. It appears that variations in both clutch size (frequency) and egg size are important sources of variation in reproductive output.

scholarly journals Semiannual and annual variations in the height of the ionospheric F2-peak

2000 ◽  
Vol 18 (3) ◽  
pp. 285-299 ◽  
Author(s):  
H. Rishbeth ◽  
K. J. F. Sedgemore-Schulthess ◽  
T. Ulich
Keyword(s):  
Solar Activity ◽  
Computational Models ◽  
Annual Variation ◽  
Late Summer ◽  
Early Summer ◽  
Atmospheric Composition ◽  
Annual Variations ◽  
Composition And Structure ◽  
Semiannual Variation ◽  
Quiet Day

Abstract. Ionosonde data from sixteen stations are used to study the semiannual and annual variations in the height of the ionospheric F2-peak, hmF2. The semiannual variation, which peaks shortly after equinox, has an amplitude of about 8 km at an average level of solar activity (10.7 cm flux = 140 units), both at noon and midnight. The annual variation has an amplitude of about 11 km at northern midlatitudes, peaking in early summer; and is larger at southern stations, where it peaks in late summer. Both annual and semiannual amplitudes increase with increasing solar activity by day, but not at night. The semiannual variation in hmF2 is unrelated to the semiannual variation of the peak electron density NmF2, and is not reproduced by the CTIP and TIME-GCM computational models of the quiet-day thermosphere and ionosphere. The semiannual variation in hmF2 is approximately "isobaric", in that its amplitude corresponds quite well to the semiannual variation in the height of fixed pressure-levels in the thermosphere, as represented by the MSIS empirical model. The annual variation is not "isobaric". The annual mean of hmF2 increases with solar 10.7 cm flux, both by night and by day, on average by about 0.45 km/flux unit, rather smaller than the corresponding increase of height of constant pressure-levels in the MSIS model. The discrepancy may be due to solar-cycle variations of thermospheric winds. Although geomagnetic activity, which affects thermospheric density and temperature and therefore hmF2 also, is greatest at the equinoxes, this seems to account for less than half the semiannual variation of hmF2. The rest may be due to a semiannual variation of tidal and wave energy transmitted to the thermosphere from lower levels in the atmosphere.Key words: Atmospheric composition and structure (thermosphere - composition and chemistry) - Ionosphere (mid-latitude ionosphere)

scholarly journals On the annual variation of the magnetic declination, at different periods of the day

1854 ◽  
Vol 6 ◽  
pp. 73-74
Keyword(s):  
Annual Variation ◽  
Graphical Representation ◽  
Horizontal Line ◽  
Annual Variations ◽  
Cape Of Good Hope ◽  
Magnetic Declination ◽  
Annual Range ◽  
The Hours ◽  
The Mean ◽  
St Helena

In this communication the author has arranged and presented together the Annual variations which the magnetic declination undergoes at every hour of the day at the four Colonial Observatories established by the British government, at Toronto, Hobarton, the Cape of Good Hope and St. Helena. This has been done by means of a graphical representation, in which the annual variations at every hour are shown by vertical lines varying in length according to the amount of the range of the annual variation at each hour; each line having also small cross lines marking the mean positions of the several months in the annual range. The mean declination in the year at the respective hours is marked by a horizontal line which crosses all the verticals at each station. The hours are those of mean solar time at each station, the day commencing at noon.

scholarly journals Seasonal features of geomagnetic activity: a study on the solar activity dependence

2021 ◽  
Vol 39 (5) ◽  
pp. 929-943
Author(s):  
Adriane Marques de Souza Franco ◽  
Rajkumar Hajra ◽  
Ezequiel Echer ◽  
Mauricio José Alves Bolzan
Keyword(s):  
Solar Wind ◽  
Solar Activity ◽  
Geomagnetic Activity ◽  
Annual Variation ◽  
Geomagnetic Storms ◽  
Solar Wind Speed ◽  
Solar Cycles ◽  
Annual Variations ◽  
Long Duration ◽  
Activity Dependence

Abstract. Seasonal features of geomagnetic activity and their solar-wind–interplanetary drivers are studied using more than five solar cycles of geomagnetic activity and solar wind observations. This study involves a total of 1296 geomagnetic storms of varying intensity identified using the Dst index from January 1963 to December 2019, a total of 75 863 substorms identified from the SuperMAG AL/SML index from January 1976 to December 2019 and a total of 145 high-intensity long-duration continuous auroral electrojet (AE) activity (HILDCAA) events identified using the AE index from January 1975 to December 2017. The occurrence rates of the substorms and geomagnetic storms, including moderate (-50nT≥Dst>-100nT) and intense (-100nT≥Dst>-250nT) storms, exhibit a significant semi-annual variation (periodicity ∼6 months), while the super storms (Dst≤-250 nT) and HILDCAAs do not exhibit any clear seasonal feature. The geomagnetic activity indices Dst and ap exhibit a semi-annual variation, while AE exhibits an annual variation (periodicity ∼1 year). The annual and semi-annual variations are attributed to the annual variation of the solar wind speed Vsw and the semi-annual variation of the coupling function VBs (where V = Vsw, and Bs is the southward component of the interplanetary magnetic field), respectively. We present a detailed analysis of the annual and semi-annual variations and their dependencies on the solar activity cycles separated as the odd, even, weak and strong solar cycles.

Inter-annual variation in the trophic niche of Magellanic penguins Spheniscus magellanicus during the pre-molt period in the Beagle Channel

2020 ◽  
Vol 655 ◽  
pp. 215-225
Author(s):  
S Dodino ◽  
L Riccialdelli ◽  
MJ Polito ◽  
K Pütz ◽  
A Raya Rey
Keyword(s):  
Diet Composition ◽  
Annual Variation ◽  
Isotope Analysis ◽  
Trophic Niche ◽  
Carbon And Nitrogen ◽  
Spheniscus Magellanicus ◽  
Beagle Channel ◽  
Annual Variations ◽  
Magellanic Penguins ◽  
Key Species

Inter-annual variations in the diets of seabirds are often a reflection of resource availability, with population dynamics and community structure implications. We investigated the trophic niche of Magellanic penguins Spheniscus magellanicus during the pre-molt stage in 6 years (2009 and 2013-2017) at Martillo Island, Beagle Channel, Argentina, using carbon and nitrogen stable isotope analysis of feathers. We found higher values in 2009 compared to the other years for both isotopes and estimated different proportions of prey in the diet of Magellanic penguins throughout the years. In 2009, penguins consumed mainly a mixture of benthic and benthopelagic fish, whereas from 2013 to 2017, the proportion of the pelagic form of squat lobster Munida gregaria, considered a key species in the Beagle Channel, increased over time and nearly dominated diets in 2017. Our results confirm that Magellanic penguins act as sentinels, reflecting shifts in the marine community of the Beagle Channel via inter-annual variation in their trophic niche and diet composition.

scholarly journals Transport analysis and source attribution of seasonal and interannual variability of CO in the tropical upper troposphere and lower stratosphere

2013 ◽  
Vol 13 (1) ◽  
pp. 129-146 ◽  
Author(s):  
J. Liu ◽  
J. A. Logan ◽  
L. T. Murray ◽  
H. C. Pumphrey ◽  
M. J. Schwartz ◽  
...  
Keyword(s):  
Annual Cycle ◽  
Annual Variation ◽  
Lower Stratosphere ◽  
Transport Model ◽  
Boreal Summer ◽  
Lower Altitude ◽  
Model Simulations ◽  
Upper Troposphere ◽  
Annual Variations ◽  
Upward Transport

Abstract. We used the GEOS-Chem chemistry-transport model to investigate impacts of surface emissions and dynamical processes on the spatial and temporal patterns of CO observed by the Microwave Limb Sounder (MLS) in the upper troposphere (UT) and lower stratosphere (LS). Model simulations driven by GEOS-4 and GEOS-5 assimilated fields present many features of the seasonal and inter-annual variation of CO in the upper troposphere and lower stratosphere. Both model simulations and the MLS data show a transition from semi-annual variations in the UT to annual variations in the LS. Tagged CO simulations indicate that the semi-annual variation of CO in the UT is determined mainly by the temporal overlapping of surface biomass burning from different continents as well as the north-south shifts of deep convection. Both GEOS-4 and GEOS-5 have maximum upward transport in April and May with a minimum in July to September. The CO peaks from the Northern Hemisphere (NH) fires propagate faster to the LS than do those from the Southern Hemisphere (SH) fires. Thus the transition from a semi-annual to an annual cycle around 80 hPa is induced by a combination of the CO signal at the tropopause and the annual cycle of the Brewer-Dobson circulation. In GEOS-5, the shift to an annual cycle occurs at a lower altitude than in MLS CO, a result of inadequate upward transport. We deduce vertical velocities from MLS CO, and use them to evaluate the velocities derived from the archived GEOS meteorological fields. We find that GEOS-4 velocities are similar to those from MLS CO between 215 hPa and 125 hPa, while the velocities in GEOS-5 are too low in spring and summer. The mean tropical vertical velocities from both models are lower than those inferred from MLS CO above 100 hPa, particularly in GEOS-5, with mean downward, rather than upward motion in boreal summer. Thus the models' CO maxima from SH burning are transported less effectively than those in MLS CO above 147 hPa and almost disappear by 100 hPa. The strongest peaks in the CO tape-recorder are in late 2004, 2006, and 2010, with the first two resulting from major fires in Indonesia and the last from severe burning in South America, all associated with intense droughts.

scholarly journals 2nd Geomagnetic Information Renewal Cycle in the Republic of Croatia – First Results

2018 ◽  
Vol 17 (30) ◽  
pp. 4-15 ◽  
Author(s):  
Mario Brkić ◽  
Marko Pavasović ◽  
Matej Varga ◽  
Marijan Grgić
Keyword(s):  
Annual Variation ◽  
The State ◽  
Repeat Station ◽  
First Results ◽  
Primary Location ◽  
The Republic ◽  
Renewal Cycle

The 2nd Geomagnetic Information Renewal Cycle started in 2017, pursuant to a request from the State Geodetic Administration and Ministry of Defence to ensure actual declination and its annual variation across the territory of Republic of Croatia. A test survey was performed at POKUpsko as part of the project in 2017. The PRM1 Primary Repeat Station had been destroyed, and the survey performed at a secondary location established in 2011, which subsequently became the primary location, known as PRM2. In this paper, the results of 2017 measurements reductions are presented, along with reductions in PRM1 and PRM2 measurements in 2011, and differences between the PRM1 and PRM2 locations, which are necessary to maintain the continuity of measurements at Pokupsko.

scholarly journals Annual variations in the severity of attack by Argentine stem weevil on perennial ryegrass

1990 ◽  
pp. 221-225 ◽  
Author(s):  
W.F. Hunt
Keyword(s):  
Lolium Perenne ◽  
Perennial Ryegrass ◽  
Annual Variation ◽  
Plastic Ring ◽  
Lolium Perenne L ◽  
Annual Variations ◽  
Site Density ◽  
Listronotus Bonariensis ◽  
Line Transects ◽  
Weather Parameters

Experiments on the effects of Argentine stem weevil (Listronotus bonariensis (Kuschel)) predation on perennial ryegrass (Lolium perenne L.) were carried out at Palmerston North from 1978 to 1986. A tagged tiller technique was used to assess the probability that any tiller would be attacked by Argentine stem weevil larvae. After grazing by sheep, a single tiller was tagged with a plastic ring at 25 sites 15 cm apart along line transects through each plot, and examined twice weekly throughout the seasons during which Argentine stem weevil is active. Annual variation at Palmerston North was substantial, with the probability of a low endophyte 'Grasslands Nui' perennial ryegrass tiller being attacked ranging from 55% to 95%. ASW annual larvae production calculated from the probability of tiller site damage and the tiller site density varied from 800 to 3000/m'. Variations in the severity of attack of this magnitude are sufficient to explain the variability in the success of sowings of low endophyte grass. Variations in annual larvae production were not correlated with weather parameters, but may be related to natural cyclic disease infestations. Keywords Argentine stem weevil, 'Grasslands Nui' perennial ryegrass, endophyte

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