Twelve years of ground-tilt measurements on the Soufriere of St. Vincent, 1977–1989     

R S Fiske  J B Shepherd 《Bulletin of Volcanology》1990,52(3):227-241

Five ground-tilt stations were established on the flanks of the Soufriere of St. Vincent; two in 1977, two in 1980, and one in 1983. Four of these stations have survived; two consist of lines oriented radially to the volcano, and the other two consist of cross-shaped arrays. Collectively, this network showed that the volcano inflated gradually before the eruption of 1979 and then deflated rapidly during the eruption and for about a year after it had ended. The volcano then reinflated during much of 1981 and inflated only slightly, if at all, during the 7-year period 1982–1989. The measured amount of ground tilt from 1977 to 1989 was relatively small; the maximum recorded change of radial tilt at a station 6.5 km from the summit of the volcano totaled about 20 rad. Local seismicity correlates well with measured ground deformation: numerous earthquakes accompanied the 1979–1981 deflation/inflation cycle; relatively few earthquakes occurred during the 1982–1989 period of little or no ground deformation. In the hope that the experience we have gained might be of use to others who are considering a program of ground-tilt monitoring on volcanoes elsewhere in the humid tropics, we describe many practical aspects of our program that have evolved over the years. For example: (1) stainless steel bench marks cemented into solid bedrock appear to be stable for at least 12 years, (2) bench marks can be located in concrete-filled drums where bedrock is absent, (3) bench marks should be concealed to protect them from vandalism, (4) care must be exercised where sight lines graze the ground (<0.5 m), and (5) automatic levels are preferable because of their efficiency of operation, especially with inexperienced personnel.  相似文献   

Energy transfer from excited N₂ and O₂ as a source of O(¹S) in the Aurora     

A.W. Yau  G.G. Shepherd 《Planetary and Space Science》1979,27(4):481-490

It is proposed that energy transfer from excited O₂ contributes to the production of O(¹S) in aurora. An analysis is presented of the OI5577 Å emission in an IBC II⁺ aurora between 90 and 130 km. The volume emission rate of the emission at these altitudes is consistent with the production rate of O(¹S) by energy transfer to O(³P) from N₂ in the A³Σ₂⁺ state and O₂ in the A³Σ_u⁺, C³Δc¹Σ_u^? states, the N₂A state being populated by direct electron impact excitation and B → A cascade and the excited O₂ states by direct excitation. Above the peak emission altitude (~105 km), energy transfer from N₂A is the predominant production mechanism for O(¹S). Below it, the contribution from quenching of the O₂ states becomes significant.  相似文献   

A laboratory discharge lamp source for the O2 atmospheric bands and OI 5577 Å and 6300 Å lines of a known line width     

R.N. Peterson  L.L. Cogger  H.T. Meredith  G.G. Shepherd 《Planetary and Space Science》1979,27(9):1209-1212

A laboratory discharge lamp is described which strongly emits the forbidden OI 5577 and 6300 Å lines and the O₂ (0?0) atmospheric band. Experimental measurements confirm that these atomic and molecular species are in thermal equilibrium with one another, so that a rotational temperature measurement of the O₂ atmospheric band allows one to deduce the line widths of the 5577 and 6300 Å emissions. This thus provides a useful calibration source for interferometric measurements of these emissions.  相似文献   

Assessment of satellite-based rainfall estimates in urban areas in different geographic and climatic regions   总被引：1，自引：0，他引：1  

Woo Suk Han  Steven J. Burian  J. Marshall Shepherd 《Natural Hazards》2011,56(3):733-747

This paper presents an assessment of the 3B42 research version rainfall product from NASA’s Tropical Rainfall Measuring Mission Multi-satellite Precipitation Analysis (TMPA). The study provides new results of TMPA data accuracy in urban areas and highlights trends associated with the climatological indicators of temperature and relative humidity in cities. Ten years (1998-2007) of TMPA data were analyzed for three case study cities in the United States (Houston, Atlanta, and Las Vegas) and one in Korea (Cheongju), representing semi-arid to humid climates. At each location, an urbanized river basin and non-urbanized river basin were selected and comparisons between TMPA and rain gage observations were made for recorded storm events in the study period, the largest storm events by total depth, and selected hurricanes and topical storms. The results indicate TMPA data match well with rain gage observations at all locations. TMPA is slightly underestimated for semi-arid regions and overestimated for humid regions. The relative magnitude of TMPA rain event accumulation compared to rain gage accumulation is noted to be smaller for urbanized watersheds and high intensity events. The correlation of TMPA accuracy with temperature and relative humidity and the analysis of accuracy by season indicate TMPA is more accurate for convective rainfall events. This suggests a possible linkage between the observed urban-modified temperatures, hypothesized enhanced convection, and improved TMPA accuracy in urban areas.  相似文献   

Some Observations on the Folkestone Beds Around Farnham     

W. Shepherd 《Proceedings of the Geologists' Association. Geologists' Association》1934,45(4):436-444

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TeV J2032+4130: a not-so-dark accelerator?     

Y. M. Butt  J. A. Combi  J. Drake  J. P. Finley  A. Konopelko  M. Lister  J. Rodriguez  D. Shepherd 《Monthly notices of the Royal Astronomical Society》2008,385(4):1764-1770

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Spatial and temporal characteristics of rainfall in a data-scarce region: case of Kinshasa and Bas-Congo in Democratic Republic of Congo     

Clarisse Kaka Mufwaya  Shepherd Muchuru 《水文科学杂志》2013,58(11):2024-2032

ABSTRACT

The aim of the present paper was to improve understanding of the rainfall dynamics in Bas-Congo and Kinshasa provinces, in Democratic Republic of Congo (DRC). The first objective of the study was achieved by analysing the spatial correlations of monthly, seasonal, annual and individual monthly rainfall amounts of Kinshasa and Bas-Congo. The second objective was achieved through investigating and quantifying the temporal trends and their spatial variations. The results demonstrated notably high average inter-station correlation of +0.63 for dry season series, followed by monthly rainfall series with an average inter-station correlation of +0.58. However, there was no station with a stable monthly rainfall regime, i.e. with mean precipitation concentration index lower than 10% (it varies between 14.2 and 21.9%). Moreover, Kinshasa experienced an increase of rainfall with an average annual rate of change of +4.59 mm/year for the period 1961–2006. The results will be helpful for efficient water resources management and for mitigating the adverse impacts of future extreme drought or flood occurrences.