Hourly Mean Values Research Articles

Lunar magnetic variations

Displayed daygraphs of magnetic observatory hourly mean values and of lunar magnetic variations reconstructed from spherical harmonic coefficients are used to illustrate the difficulties that arise in separating lunar magnetic effects from those associated with the 27 day recurrence tendency in magnetic activity.

A new method for the determination of atmospheric turbidity

Atmospheric turbidity is usually measured using either a pyrheliometer fitted with a red RG630 filter or a Volz sun photometer, the turbidity coefficients so determined being designated as β and B, respectively. Both techniques are subject to error, the former in underestimating high turbidities and the latter in giving rise to errors at low turbidities. The present paper describes a new, simpler and less expensive method of evaluating B from measurements of direct and diffuse solar radiation, made as a routine at principal radiation stations. Using a theoretical model for determining the attenuation of solar radiation due to absorption and scattering by water vapour and other gases, dust and aerosols in the atmosphere, an expression for the ratio of diffuse to direct solar radiation D/I h , is derived as a function of β. Then, from the hourly mean values of global and diffuse solar radiation routinely recorded at principal radiation stations, D/I h is calculated. β can now be readily evaluated using a special nomogram based on the formula relating β to D/I h . The values of B derived for Indian stations using the above technique show remarkable internal consistency and stability, proving its utility and reliability. DOI: 10.1111/j.1600-0889.1984.tb00051.x

Geomagnetic variations and field-aligned currents at Northern high-latitudes, and their relations to the solar wind parameters

By using statistical analysis to study the relation between the interplanetary and geomagnetic fields, geomagnetic variations have been detected that are controlled by different parameters of the solar wind. The equivalent current systems for these geomagnetic variations have been determined for the 1968 summer and winter seasons from data from 14 high latitude stations. It has been shown that the geomagnetic field at high latitudes (0> 60°) can be represented by a sum of fields controlled by components of the Interplanetary Magnetic Field (I.M .F.) and by the velocity and density of the solar wind plasma. A correlation model is proposed by means of which hourly-mean values of the three components of the geomagnetic field vector at high latitudes may be determined from hourly-mean values of the components B x ,B y and B z of the I.M .F. The space—time distribution of field-aligned currents has been reconstructed from the horizontal com ponent of the ground level geomagnetic field variation. The correlation model of field-aligned currents has been obtained for high latitudes (0 ^ 60°). According to the model the value and direction of the field-aligned current j , are determined by I.M .F . components and spatial coordinates. The proposed model of field-aligned currents enables the nature of the actual magnetic disturbance registered during a given pass of the TRIAD and ISIS-2 satellites through the high latitude region to be interpreted. Moreover it enables some discrepancies between observations and the models of field-aligned currents proposed in the literature to be understood.

Effect of labetalol on continuous ambulatory blood pressure.

1 The hypotensive action of labetalol was evaluated during 24 h by continuous intra-arterial ambulatory monitoring in 14 patients. The dose used ranged from 300-1800 mg daily. 2 The drug caused a significant reduction of systolic BP in 19 and diastolic BP in 20 of the 24 h of monitoring. Heart rate was also reduced but less markedly than BP. 3 The rapid early morning increase in BP was also effectively controlled. 4 The mild pre-waking increase in BP was not significantly reduced. 5 Labetalol treatment reduced the variation in systolic BP from the lowest observed quarter-hourly mean as compared with pre- treatment values. 6 The quarter hourly mean values were consistently smooth and revealed no sudden variations which might have resulted from postural hypotension.

The lunar and solar daily geomagnetic variations at Sabhawala and Hyderabad

Summary. The first four harmonics of the lunar, L, and the solar, S, daily geomagnetic variations in the H, D and Z elements are determined for the observatories at Sabhawala and Hyderabad. Also included are similar results for Alibag with the main lunar terms separated into parts of oceanic and ionospheric origin. The data used are the alternate hourly mean values of H, D and Z for locally selected quiet days during the IQSY period, 1964-66. The predominances of the first lunar harmonic of H at Sabhawala and Alibag, and of the second solar harmonic at Sabhawala, are pointed out and discussed. The ratios of the seasonal ranges of both L and S to the respective annual mean ranges are found relatively enhanced in two of the seasons, in comparison with. the average global values for these latitudes for the IGY/C (sunspot maximum) period. This would indicate an inverse relationship of these ratios with solar activity.

Noncyclic variation andS q harmonic dials

A method is presented for the determination of noncyclic variation in geomagnetic hourly mean values, which employs only 24 hourly values or 12 bihourly values, etc. The manner in which the method bears on the ellipticity of distributions of points onSq harmonic dials is discussed. A review of other available methods is also included.

Correlation between sunspot‐activity and daily ranges of terrestrial magnetic elements at Apia, Western Samoa, 1905 to 1929

This paper is an account of the attempt to correlate the annual mean daily ranges of the terrestrial‐magnetic elements horizontal force, vertical force, and declination as measured at the Apia Observatory during the 25‐year period 1905 to 1929 with the annual means of the Wolfer sunspot‐numbers.By the annual mean daily range of an element is meant the annual mean of the differences between the greatest and least of the monthly means of the hourly mean values. The reason for using the hourly mean values is that the data concerning the absolute ranges are not available over the entire period. The magnetic data are taken from the published reports of the Observatory, while the final relative sunspot‐numbers are those published by Wolfer and later by Brunner in Terrestrial Magnetism.