摘要:

Although the direct influences of sunspots upon the solar constant leads to short‐term decreases, an opposite nearly in phase 11 year variation in the solar constant can be modelled. This opposite behavior results primarily from global faculae (polar, network, and active region). The model attributes the observed variations in the solar constant entirely to magnetic features in the solar atmosphere. Hence, the model does not require any indirect effect of the magnetic cycle on the brightness of non‐magnetic areas of the Sun. The model uses the well studied, active region influences upon the solar constant, together with the influences of global faculae, associated with polar and general solar magnetism, studied by Sheeley. Using the present model, together with the sunspot prediction of Schatten and Sofia (1987), we predict the average solar constant to the year 1997, normalized to the mean Active Cavity Radiometer (ACRIM) and Earth Radiation Budget (ERB) observations. The model also provides a relation ΔSO=0.007 ΔRm max, for the very long term solar constant variations due to the secular changes in solar activity. We obtain a change of ∼1 W/m² for the difference between the late twentieth century solar constant and the 17th century solar constant. This supports Eddy's view that this difference could give rise to the glacial increase during the little ice age of the 17th

ISSN:0094-8276    

DOI:10.1029/GL015i002p00121

年代:1988

数据来源: WILEY

摘要:

Based on “annual” averages, a bivariate analysis of the maximum amplitude of the sunspot cycle against its minimum amplitude and the minimum value of the aa geomagnetic index (in the vicinity of sunspot cycle minimum) results in a fit that closely matches the observable record. The bilinear fit has a high coefficient of correlation (r=0.982) and a small standard deviation (s=9.5), suggesting that it may be useful for predicting the size of a sunspot cycle 3 to 4 years before maximum amplitude occurrence. Applying the fit to Cycle 22, one infers an annual average of maximum amplitude Rmaxequal to 92±19 (equivalent to 96±20, in terms of the 13‐month running mean or “smoothed” suns

ISSN:0094-8276    

DOI:10.1029/GL015i002p00125

年代:1988

数据来源: WILEY

摘要:

A bipole pattern has been observed in the locations of lightning flashes that lower positive and negative charge to earth in mesoscale storm systems. The pattern has a characteristic size of about 100 km and may last for many hours. The pattern is aligned with the upper level winds and has been observed in all seasons, but is more apparent in the fall and winter. The ratio of the positive flash density to the negative flash density is approximately 0.1, but varies from 0.05 to 0.2. This ratio occurs because there are fewer positive flashes and they are more spatially dispersed than negative flashes in storm systems.

ISSN:0094-8276    

DOI:10.1029/GL015i002p00129

年代:1988

数据来源: WILEY

摘要:

It has been discovered that the size distribution of atmospheric aerosols in air masses over central Alaska varies systematically with air temperature. Cold air masses contain relatively few, coarse aerosols. Aerosols in warm Pacific‐marine air masses, on the other hand, are plentiful in number, but their mean size and mass loading is small. There are decreasing numbers of cloud condensation nuclei, but substantial increases in aerosol mass with decreasing temperatures. We speculate that the cause is related to a combination of air pollution transport from Eurasia into the Arctic air mass and photolytic creation of nuclei in the sunlit Northern Pacifi

ISSN:0094-8276    

DOI:10.1029/GL015i002p00133

年代:1988

数据来源: WILEY

摘要:

Data from 1953 to the present indicate that major warmings in the northern hemisphere winter have not occurred when the equatorial monthly mean zonal winds are deep westerly, i.e., westerly over more than about 5/8 of the 10–85 mb layer. Sixteen winters have had a major warming in the last 35 years. Six January–February periods had deep equatorial westerlies but did not experience a major warming.Major warmings do not require deep equatorial easterlies, nor is the occurrence of a major warming significantly correlated with the sign of the zonal mean wind at any particular level between 10 and 50 mb, although as noted by previous investigators, more than half of the observed major warmings have occurred when the equatorial flow is easterly at a given level between 10 and 50 mb. We suggest that a more relevant QBO statistic may be found in the depth of QBO wind regimes.The previously proposed connection between the equatorial quasi‐biennial oscillation and the major warmings of the northern hemisphere winter is supported by these observa

ISSN:0094-8276    

DOI:10.1029/GL015i002p00136

年代:1988

数据来源: WILEY

摘要:

The stratospheric vertical distribution of CO is obtained from balloon based far infrared limb thermal emission spectra by analyzing several limb sequences of the R8 and R1 spectral lines at 34.588 cm−1and 49.932 cm−1respectively. This constitutes the first determination of the stratospheric CO profile from infrared thermal emission spectra. The results indicating 24.6±7.6 ppbv at 21 km and 34.4±10.1 ppbv at 37 km are compared with the remote sensing and in‐situ measurements by other groups and with photochemical‐dynamical model cal

ISSN:0094-8276    

DOI:10.1029/GL015i002p00140

年代:1988

数据来源: WILEY

摘要:

Midlatitude stratospheric ClO at altitudes below 22 km has been measured for the first time. Measurements were made at latitudes between 27°N and 48°N during three flights from Moffett Field, California, in June and July of 1987, with a new instrument flown on the NASA ER‐2 aircraft. The result from these flights is that the ClO mixing ratio increases from less than 0.5 pptv at 16.8 km to 2.0 pptv at 18.3 km and 10.1 pptv at 21 km. These altitude profiles agree with an extrapolated profile from our May 1986 balloon‐borne exper

ISSN:0094-8276    

DOI:10.1029/GL015i002p00144

年代:1988

数据来源: WILEY

摘要:

A confined layer characterised by narrow incoherent scatter spectra has been observed between 86 and 88 km altitude in the high latitude summertime D‐region with the EISCAT radar. Properties of the background plasma inferred from spectral measurements outside the layer are in close agreement with model predictions, but the localised minima in spectral width imply much heavier positive ions within the layer. This feature is interpreted as being due to the presence of large clustered ions with mass of the order of 500 amu, which are possibly hydrated protons with a mean hydration index of almost 3

ISSN:0094-8276    

DOI:10.1029/GL015i002p00148

年代:1988

数据来源: WILEY

摘要:

In this paper, the Kelvin‐Helmholtz (KH) and tearing instabilities at the dayside magnetopause are examined. It is found from simulations that the development of the KH instability modulates the current sheet, creating separated pinched regions. The growth rate of the tearing instability is enhanced in these pinched regions and diminished in the regions separating them. Based on these findings, we propose that a possible mechanism for patchy reconnection at the dayside magnetopause is the development of the KH instabilit

ISSN:0094-8276    

DOI:10.1029/GL015i002p00152

年代:1988

数据来源: WILEY

摘要:

A stimulated plasma wave experiment by the EXOS‐B satellite showed the appearance of echoes of plasma waves with a delay time of several msec. We examined the frequency dependence of the echoes in comparison with the observed plasma resonances and the dispersion relation of plasma waves. The propagation mode of the echoes was identified as the electrostatic electron cyclotron harmonic (ESCH) waves. The appearance regions were examined with respect to the electron density profiles in the magnetosphere that have been determined by measuring the frequencies of stimulated plasma resonances. The ESCH echoes are frequently observed in a detached plasma region. Near the plasmapause the appearance of echoes is significantly frequent in regions where the plasma density is rapidly increasing in the plasmasphere due to a strong supply from the ionsphere. Because of their propagation mode and the state of the plasma density profiles in their appearance regions in the magnetosphere, the echoes are inferred to be produced by the reflection of propagating ESCH waves from small‐scale density irregularities of environmental pla

ISSN:0094-8276    

DOI:10.1029/GL015i002p00156

年代:1988

数据来源: WILEY