摘要:

A method is presented for modeling earthquake strong ground motion, which uses the aftershocks associated with a large earthquake as Green's functions. A major earthquake, with a large rupture surface, is modeled by a collection of point sources distributed over the fault plane. The response of each point source is approximated by the ground motion of the closest associated aftershock. By using the aftershock responses, the effects of the true earth structure are included in the modeling process. This method is used to model the El Centro displacement record for the 1940 Imperial Valley earthquake.

ISSN:0094-8276    

DOI:10.1029/GL005i001p00001

年代:1978

数据来源: WILEY

摘要:

Various definitions have been adopted for the commonly used quality parameter Q, with consequent ambiguities. We propose a standard definition of the intrinsic Q of a linear viscoelastic material, and discuss its connection with several other measures of dissipation.

ISSN:0094-8276    

DOI:10.1029/GL005i001p00005

年代:1978

数据来源: WILEY

摘要:

The cosmogenic radioisotopes38Cl (t½= 37.3 min.) and39Cl (t½= 55.5 min.) are formed in the stratosphere in detectable quantities, and participate in the stratospheric chlorine cycles. The predominant expected chemical forms for these radioisotopes are ClO and/or ClONO2throughout most of the stratosphere. The rates for formation of HCl are sufficiently slow that most38Cl and39Cl atoms undergo radioactive decay before ever reacting to form HCl.The measurement of the fraction of38Cl and39Cl in the forms ClO and ClONO2, with a concurrent NO2measurement, can be used to measurein situthe stratospheric formation rate for ClONO2. Such experiments could be conducted at altitudes accessible to aircraft experiment

ISSN:0094-8276    

DOI:10.1029/GL005i001p00009

年代:1978

数据来源: WILEY

摘要:

In a previous paper the writer derived an explicit expression for the probability of failure of a discrete reservoir fed by a Markovian input. This is now simplified to expressions for particular cases which are characterized by the ratio of mean input to target draft. It is shown that the expressions yield some classical results in Stochastic Reservoir Theory.

ISSN:0094-8276    

DOI:10.1029/GL005i001p00013

年代:1978

数据来源: WILEY

摘要:

The role of nitrogen oxides in the tropospheric photochemical system is re‐evaluated in the light of recent measurements of the rate constants for two key reactions. A model for nitrogen oxides is discussed which yields surface NOx(NO+NO2) levels approaching 1 ppb in NOxsource regions but less than 0.1 ppb outside source regions. Applying the new rate coefficients implies increased radical concentrations and a more intense O3and CO photochemistry. Even for densities of 0.1 ppb or less, NOxstill leads to significant local O3production and conversion of HO2to OH. Unrealistic O3profiles are obtained with the new rate coefficients for surface NOxdensities of about 1 ppb, while reasonable agreement with observation is obtained with lower NOxdensities. Feedback processes between CO, NOx, OH, and CH4are also discusse

ISSN:0094-8276    

DOI:10.1029/GL005i001p00017

年代:1978

数据来源: WILEY

摘要:

Stereographic pairs of SMS/GOES images, generated simultaneously by the spin‐scan cameras of each of two geostationary satellites (SMS 1 and SMS 2, separated by 32 degrees of longitude on February 17, 1975), have been analyzed photogrammetrically to yield cloud heights with a two‐sigma uncertainty of 500 meters. The 32‐degree angle between the image plane of the two satellites, plus the distortions involved in transferring the image of a nearly full hemisphere of the earth onto a plane, required the development of a special instrument to permit stereographic compilation. Cloud heights measured stereographically compared favorably with heights of the same clouds measured by radar and IR methods. The same SMS image pairs were used to measure mountain‐top heights with a mean deviation of 0.24 km from cartographic

ISSN:0094-8276    

DOI:10.1029/GL005i001p00021

年代:1978

数据来源: WILEY

摘要:

Large quasi‐periodic fluctuations are observed simultaneously in the rotational temperature of the nightglow emission from both O2(¹Σg) and OH. The fluctuation amplitude usually is several times larger in the former and the O2(¹Σg) fluctuations often lead those of OH in phase. This behavior is consistent with that expected for internal gravity waves propagating upward over the ˜ 10 km vertical separation between the two emission layers. The most prominent periods are 1‐2 hours and the full range of oscillation in temperature at 95 km sometimes approache

ISSN:0094-8276    

DOI:10.1029/GL005i001p00025

年代:1978

数据来源: WILEY

摘要:

Measurements of the solar Lyman alpha flux and of the exobase hydrogen density distribution were made by the University of Paris experiment aboard the Orbiting Solar Observatory (OSO‐5) during the period August 1974 to August 1975. These data were obtained near the end of the solar cycle # 20, at a time of nearly minimum solar activity. To compare most accurately solar minimum and solar maximum conditions, these data were subjected to the same analysis procedures used for OSO‐5 data from 1969‐1972 (Vidal‐Madjar et al., 1973).The results are presented individually and the average exobase hydrogen density is observed to reach 3.5 × 105atoms cm−3(at 500 km) for an average exospheric temperature as low as 725 K. This result shows that the non‐thermal escape mechanism increases even more than previously observed. For low solar activity conditions, the non‐thermal escape flux can be more than a factor seven larger than the Jeans escape flux.The non‐thermal mechanisms become increasingly important at low solar activity; the minimum‐to‐maximum density ratio deduced from only dayside measurements is also observed to increase at solar minimum and may reach values as high as 3.7, although the average value is of the order of 2.1.Finally, the dayside, latitudinal sub‐solar bulge monitored from 1969 to 1972 is still observed at solar minimum and presents the same amplitude as during so

ISSN:0094-8276    

DOI:10.1029/GL005i001p00029

年代:1978

数据来源: WILEY

摘要:

Profiles of CF2Cl2, CFCl3, CCl4, and N2O in the lower stratosphere are reported from measurements made during a meridional survey in the Northern Hemisphere in the fall of 1976. The latitude distributions obtained show a marked decrease in mixing ratio with increasing latitude from about lat. 7°N in the region of the Intertropical Convergence Zone to about lat. 79°N along the 159°W meridian. The results suggest the importance of meridional transport and mixing in the stratosphere in accounting, at least in part, for the observed profile variation with latitu

ISSN:0094-8276    

DOI:10.1029/GL005i001p00033

年代:1978

数据来源: WILEY

摘要:

Nitric oxide has been measured in situ between 38.4 and 29.8 km by a new technique, photoionization mass spectrometry. Data indicate a peak mixing ratio of 5.7 ± 0.35 ppbv at 37.5 km and only 0.2 ± 0.2 ppbv at 32.8 km with a sharp gradient in concentration between 33 and 34 km. Simultaneous in‐situ measurements of the ozone concentration show no significant feature at that altitude. The rapid decrease in mixing ratio is not predicted by current the

ISSN:0094-8276    

DOI:10.1029/GL005i001p00037

年代:1978

数据来源: WILEY