scholarly journals The diurnal variation of magnetic disturbance in high latitudes

1935 ◽  
Vol 149 (867) ◽  
pp. 298-311 ◽  
Keyword(s):  
Diurnal Variation ◽  
Natural Disturbance ◽  
Universal Time ◽  
Sudden Commencement ◽  
General View ◽  
High Latitudes ◽  
Limited Region ◽  
Short Period ◽  
Distinctive Type ◽  
Unlimited Variety

1―The effect of natural disturbance on the earth’s magnetic field at any one place is at least twofold: (i) to introduce a regular variation (S d ) periodic within the day and additional to, as well as different in type from (except in a limited region round the magnetic axis pole), the variation associated with quiet days (S q ); and (ii) to suppose on S d irregular changes which may either be of the distinctive type peculiar to large storms especially in low latitudes and generally preceded by the particular type of perturbation known as a sudden commencement, or the changes in the field may be of the apparently nondescript class which comprises an unlimited variety of short-period irregular oscillations. Of these effects of disturbances S d is definitely a local time phenomenon: the sudden commencement with subsequent depression in the horizontal component of the field as definitely follows universal time. For the irregular and unclassified oscillations in moderate and high latitudes a diurnal variation in their incidence has been shown to exist for a few isolated localities. But in the general view it is not known whether this aspect of disturbance is controlled by local or universal time. Nor is it known whether the form of the diurnal variation in disturbance (which variation we shall denote by D) varies in any systematic way with latitude.

scholarly journals The Diurnal Variation in Stratospheric Ozone from MACC Reanalysis, ERA-Interim, WACCM, and Earth Observation Data: Characteristics and Intercomparison

Atmosphere ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 625
Author(s):  
Ansgar Schanz ◽  
Klemens Hocke ◽  
Niklaus Kämpfer ◽  
Simon Chabrillat ◽  
Antje Inness ◽  
...  
Keyword(s):  
Diurnal Variation ◽  
Climate Model ◽  
Stratospheric Ozone ◽  
Polar Vortex ◽  
Model Systems ◽  
Atmospheric Composition ◽  
The Arctic ◽  
Observation Data ◽  
High Latitudes ◽  
Free Running

In this study, we compare the diurnal variation in stratospheric ozone of the MACC (Monitoring Atmospheric Composition and Climate) reanalysis, ECMWF Reanalysis Interim (ERA-Interim), and the free-running WACCM (Whole Atmosphere Community Climate Model). The diurnal variation of stratospheric ozone results from photochemical and dynamical processes depending on altitude, latitude, and season. MACC reanalysis and WACCM use similar chemistry modules and calculate a similar diurnal cycle in ozone when it is caused by a photochemical variation. The results of the two model systems are confirmed by observations of the Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES) experiment and three selected sites of the Network for Detection of Atmospheric Composition Change (NDACC) at Mauna Loa, Hawaii (tropics), Bern, Switzerland (midlatitudes), and Ny-Ålesund, Svalbard (high latitudes). On the other hand, the ozone product of ERA-Interim shows considerably less diurnal variation due to photochemical variations. The global maxima of diurnal variation occur at high latitudes in summer, e.g., near the Arctic NDACC site at Ny-Ålesund, Svalbard. The local OZORAM radiometer observes this effect in good agreement with MACC reanalysis and WACCM. The sensed diurnal variation at Ny-Ålesund is up to 8% (0.4 ppmv) due to photochemical variations in summer and negligible during the dynamically dominated winter. However, when dynamics play a major role for the diurnal ozone variation as in the lower stratosphere (100–20 hPa), the reanalysis models ERA-Interim and MACC which assimilate data from radiosondes and satellites outperform the free-running WACCM. Such a domain is the Antarctic polar winter where a surprising novel feature of diurnal variation is indicated by MACC reanalysis and ERA-Interim at the edge of the polar vortex. This effect accounts for up to 8% (0.4 ppmv) in both model systems. In summary, MACC reanalysis provides a global description of the diurnal variation of stratospheric ozone caused by dynamics and photochemical variations. This is of high interest for ozone trend analysis and other research which is based on merged satellite data or measurements at different local time.

scholarly journals Correction to “Universal time dependence of nighttimeFregion densities at high latitudes”

1986 ◽  
Vol 91 (A1) ◽  
pp. 381
Author(s):  
O. de la Beaujardière ◽  
V. B. Wickwar ◽  
G. Caudal ◽  
J. M. Holt ◽  
J. D. Craven ◽  
...  
Keyword(s):  
Time Dependence ◽  
Universal Time ◽  
High Latitudes

scholarly journals Preliminary evidence for seasonality of Covid-19 due to ultraviolet radiation

F1000Research ◽  
2020 ◽  
Vol 9 ◽  
pp. 658
Author(s):  
Christos Karapiperis ◽  
Panos Kouklis ◽  
Stelios Papastratos ◽  
Anastasia Chasapi ◽  
Antoine Danchin ◽  
...  
Keyword(s):  
Uv Radiation ◽  
Biomedical Research ◽  
Preliminary Evidence ◽  
High Latitudes ◽  
Multiple Factors ◽  
Short Period ◽  
The World ◽  
June Solstice ◽  
Explicit Consideration ◽  
Key Parameter

The Covid-19 pandemic has spread across the world during early 2020, with unforeseen consequences. Beyond social measures and biomedical research, it is important to assess the seasonality of the epidemic to inform strategies, with limited available data in the short period of time between the March equinox and the June solstice. While the effect of multiple factors is being investigated, little attention has been paid to ultraviolet (UV) radiation, a key parameter of seasonal forcing. We review the effects of UV radiation, proposing it as a potential element of seasonality, and provide evidence from the current literature and scant, yet revealing, observations. Explicit consideration should be given to UV radiation for the seasonality of Covid-19 at high latitudes and altitudes, based on the SARS and MERS epidemics and coronavirus diseases, and not just the ‘warmer days’ of summer.

Forest turnover and the dynamics of bole wood litter in subalpine balsam fir forest

1985 ◽  
Vol 15 (1) ◽  
pp. 262-268 ◽  
Author(s):  
Gerald E. Lang
Keyword(s):  
Forest Floor ◽  
Natural Disturbance ◽  
Balsam Fir ◽  
Balance Model ◽  
Natural Disturbances ◽  
Maximum Value ◽  
Short Period ◽  
Bole Biomass ◽  
Live Tree ◽  
Mature Stands

A chronosequence of three stands of balsam fir was sampled in 1974 and 1982; during these 8 years, recruitment was absent so mortality alone accounted for an 18–30% decrease in live tree density. In a mature 78-year-old stand, the mass of bole wood on the forest floor was 1.4 kg•m−2 compared with an estimated aboveground live and dead bole biomass of 17.2 kg•m−2. During 5 years of repetitive sampling, annual bole input to the forest floor was episodic and variable in time and space, ranging from 3 to 365 g•m−2•year−1. A mass balance model was used to characterize the changes in wood litter on the forest floor. If most of the live trees die within a short period of time, bole input would occur in a pulse event and cause a peak in wood litter mass, which would then decline over time (and with stand maturation) as decomposition prevails. The assumption of steady-state conditions for wood litter is not valid; rather the mass of wood litter will wax and wane through time. Over a landscape, spatial patterns in the abundance of wood litter reflect a stand's history; old mature stands would have little wood litter while young regenerating stands would have large amounts. A maximum value for wood litter would be found in a stand located immediately behind a fir wave. Natural disturbances from wind and avalanches lead to contrasting patterns with high and low wood litter values, respectively. About 41% of forest turnover in the balsam fir zone is initiated from natural disturbance and fir waves.

IRREGULAR MAGNETIC ACTIVITY IN NORTHERN CANADA WITH SPECIAL REFERENCE TO AEROMAGNETIC SURVEY PROBLEMS

Geophysics ◽  
1957 ◽  
Vol 22 (3) ◽  
pp. 646-659 ◽  
Author(s):  
K. Whitham ◽  
E. I. Loomer
Keyword(s):  
Magnetic Activity ◽  
Auroral Zone ◽  
Maximum Activity ◽  
High Latitudes ◽  
Aeromagnetic Survey ◽  
Northern Canada ◽  
K Index ◽  
Seasonal Characteristics ◽  
Short Period ◽  
Two Peaks

An investigation of the diurnal and seasonal characteristics of irregular magnetic activity in northern Canada, using two indices of disturbance, shows that in general the K index provides a reliable but smoothed measure of short period activity. Two peaks of activity are evident, a day‐time peak, dominant inside the polar cap, and a night peak, dominant south of the auroral zone. The latter occurs within one hour of local geomagnetic midnight at four Canadian observatories, whereas the day‐time peak occurs progressively later at higher latitudes. The maximum activity occurs in the equinoxes at latitudes near the auroral zone, and during the summer solstice at very high latitudes. Measurements of range at the most disturbed observatory suggest that aeromagnetic surveying in high latitudes is in general feasible, but that for accurate reconnaissance work it is very advantageous to plan operations, so far as conditions permit, taking account of the systematic diurnal variation of disturbance. It is shown that errors of about one half the assumed diurnal change between base lines will occur and sufficient data is given to allow approximate predictions of the optimum length of flight lines.

scholarly journals Are There Different Types of Variability Among B Stars?

1980 ◽  
Vol 58 ◽  
pp. 353-359 ◽  
Author(s):  
J.-P. Sareyan ◽  
J.-M. Le Contel ◽  
J.-C. Valtier ◽  
D. Ducatel
Keyword(s):  
Internal Structure ◽  
Small Area ◽  
A Priori ◽  
Hydrogen Burning ◽  
Limited Region ◽  
B Stars ◽  
Internal Structures ◽  
Short Period ◽  
Different Types ◽  
Hr Diagram

Almost every survey for β Cephei detection has been restricted to the small area of the HR diagram that contained the 15-20 first discovered. (Table 1). Of course, every new short period pulsating star found in such an a priori limited region has strengthened the impression that an instability box could be derived from the study of the statistics of β Cep variables. That conclusion could have led to the discovery of a β Cep pulsation mechanism related to a particular mass - age internal structure status. On the contrary if the phenomenon is due to a mechanism acting in a wider extension of the HR diagram (and so probably better related to envelope properties) one still has to explain why its detection seems to be easier in the B0-B1 zone. Moreover, even within the “instability box” some classical β Cep could be either in core hydrogen burning phase or others in shell hydrogen burning phase, i.e. with quite different internal structures.

scholarly journals Short-Period Fluctuations in the Numbers of Barnacle Larvae, With Notes on Comparisons between Pump and Net Plankton Hauls

1949 ◽  
Vol 28 (2) ◽  
pp. 353-369 ◽  
Author(s):  
K. A. Pyefinch
Keyword(s):  
Diurnal Variation ◽  
Surface Waters ◽  
Diurnal Variations ◽  
Larval Stages ◽  
Short Period ◽  
The Hours ◽  
Time Of Year ◽  
Balanus Balanoides

Records are given of the numbers of barnacle larvae obtained from samples of water pumped through a plankton net. Several series of hauls were made at intervals over the time of year when barnacle larvae are abundant.The numbers of the cyprid larvae of Balanus balanoides in the surface waters show a diurnal variation, being markedly less during the hours of darkness. This conclusion may also apply to the cyprids of B. crenatus and Verruca stroemia, but the numbers of these larvae were too small to permit reliable conclusions to be drawn. There is some evidence that similar diurnal variations occur in larval stages other than the cyprid.

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