Quantifying urban land cover change between 2001 and 2006 in the Gulf of Mexico region     

George Xian  Collin Homer  Brett Bunde  Patrick Danielson  Jon Dewitz  Joyce Fry 《国际地球制图》2013,28(6):479-497

We estimated urbanization rates (2001–2006) in the Gulf of Mexico region using the National Land Cover Database (NLCD) 2001 and 2006 impervious surface products. An improved method was used to update the NLCD impervious surface product in 2006 and associated land cover transition between 2001 and 2006. Our estimation reveals that impervious surface increased 416 km² with a growth rate of 5.8% between 2001 and 2006. Approximately 1110.1 km² of non-urban lands were converted into urban land, resulting in a 3.2% increase in the region. Hay/pasture, woody wetland, and evergreen forest represented the three most common land cover classes that transitioned to urban. Among these land cover transitions, more than 50% of the urbanization occurred within 50 km of the coast. Our analysis shows that the close-to-coast land cover transition trend, especially within 10 km off the coast, potentially imposes substantial long-term impacts on regional landscape and ecological conditions.  相似文献   

An assessment of the surface water resources of the Juba-Shabelle basin in southern Somalia     

H. A. Houghton-Carr  C. R. Print  M. J. Fry  H. Gadain  P. Muchiri 《水文科学杂志》2013,58(5):759-774

Abstract

The water resources of the Juba and Shabelle rivers in southern Somalia are important for irrigation and food production, but are influenced by seasonal floods. Prior to the outbreak of civil war in 1991, the Somali Ministry of Agriculture successfully operated a hydrometric network covering the Juba and the Shabelle, data from which provided input to a flow forecasting model. The war resulted in the neglect and abandonment of monitoring stations and an enforced cessation of data collection and management. In 2001 and 2002, part of the pre-war hydrometric network was reinstated and water levels were again recorded at some stations. This paper examines the implications of the 11-year hiatus in data collection, and the now much reduced monitoring network, for assessing and managing the surface water resources. The problems faced have relevance to other basins, within Africa and elsewhere, where there has been a similar decline in data collection.

Citation Houghton-Carr, H. A., Print, C. R., Fry, M. J., Gadain, H. & Muchiri, P. (2011) An assessment of the surface water resources of the Juba-Shabelle basin in southern Somalia. Hydrol. Sci. J. 56(5), 759–774.  相似文献   

Chandra observations of Comet 9P/Tempel 1 during the Deep Impact campaign     

C.M. Lisse  K. Dennerl  S.J. Wolk  T.H. Zurbuchen  R. Hoekstra  C.D. Fry  T. Mäkinen 《Icarus》2007,190(2):391-405

We present results from the Chandra X-ray Observatory's extensive campaign studying Comet 9P/Tempel 1 (T1) in support of NASA's Deep Impact (DI) mission. T1 was observed for ∼295 ks between 30th June and 24th July 2005, and continuously for ∼64 ks on July 4th during the impact event. X-ray emission qualitatively similar to that observed for the collisionally thin Comet 2P/Encke system [Lisse, C.M., Christian, D.J., Dennerl, K., Wolk, S.J., Bodewits, D., Hoekstra, R., Combi, M.R., Mäkinen, T., Dryer, M., Fry, C.D., Weaver, H., 2005b. Astrophys. J. 635 (2005) 1329-1347] was found, with emission morphology centered on the nucleus and emission lines due to C, N, O, and Ne solar wind minor ions. The comet was relatively faint on July 4th, and the total increase in X-ray flux due to the Deep Impact event was small, ∼20% of the immediate pre-impact value, consistent with estimates that the total coma neutral gas release due to the impact was 5×¹⁰⁶ kg (∼10 h of normal emission). No obvious prompt X-ray flash due to the impact was seen. Extension of the emission in the direction of outflow of the ejecta was observed, suggesting the presence of continued outgassing of this material. Variable spectral features due to changing solar wind flux densities and charge states were clearly seen. Two peaks, much stronger than the man-made increase due to Deep Impact, were found in the observed X-rays on June 30th and July 8th, 2005, and are coincident with increases in the solar wind flux arriving at the comet. Modeling of the Chandra data using observed gas production rates and ACE solar wind ion fluxes with a CXE mechanism for the emission is consistent, overall, with the temporal and spectral behavior expected for a slow, hot wind typical of low latitude emission from the solar corona interacting with the comet's neutral coma, with intermittent impulsive events due to solar flares and coronal mass ejections.  相似文献   

Predicting the Arrival Time of Shock Passages at Earth   总被引：1，自引：0，他引：1  

Chin-Chun?WuEmail author  C.?D.?Fry  D.?Berdichevsky  M.?Dryer  Z.?Smith  T.?Detman 《Solar physics》2005,227(2):371-386

The purpose of this parametric study is to predict the arrival time at Earth of shocks due to disturbances observed on the Sun. A 3D magnetohydrodynamic (MHD) simulation code is used to simulate the evolution of these disturbances as they propagate out to 1 AU. The model in Han, Wu and Dryer (1988) uses solar data for input at 0.08 AU (18 solar radii). The initial shock speed (ISS) is assumed to be constant from the corona to 0.08 AU. We investigate how variations of this ISS affect the arrival times of the shock at Earth. This basic parametric study, however, does not consider inhomogeneous background solar wind structures such as corotating interaction regions and their precursor stream–stream interactions, nor interplanetary manifestations of complex coronal mass ejecta such as magnetic clouds. In the latter case, only their associated shocks are considered. Because the ambient (pre-existing background) solar wind speed is known to affect the shock arrival time at 1 AU, we also simulated events with various background solar wind speeds (BSWS) to investigate this effect. The results show that the shock arrival time at Earth depends on the BSWS, the speed of solar disturbances, their size, and their source location at the Sun. However, it is found that for a sufficiently large momentum input, the shock arrival time at Earth is not significantly affected by the pre-existing solar wind speed.  相似文献   

Economic‐Development Stakeholder Perspectives on Boomtown Dynamics in the Eagle Ford Shale,Texas          下载免费PDF全文

Trey Murphy  Christian Brannstrom  Matthew Fry  Michael Ewers 《Geographical review》2018,108(1):24-44

Unconventional oil and gas production in the United States reversed a decades‐old trend of rising oil imports, provided an argument for lifting the U.S. crude oil export ban and motivated the development of domestic natural gas export facilities. But the most visible impact of unconventional‐hydrocarbon extraction is the creation of boomtowns in rural regions. Despite widespread media coverage, scholarly analysis of boomtowns is restricted to regional econometric studies with little attention to how economic stakeholders understand and respond to booming economies. Here we analyze interviews with key economic stakeholders in the Eagle Ford Shale in Texas. Respondents consider their community's economic success relative to the price of oil and indicate concerns about the deterioration of roads, high housing demand, and skyrocketing wages. We also re‐examine John Gilmore's foundational work on boomtowns in the 1970s in the context of contemporary unconventional extraction.  相似文献   

Seasonal Fisheries Changes in Low-Rainfall Mangrove Ecosystems of Iran     

Maryam Shahraki  Brian Fry 《Estuaries and Coasts》2016,39(2):529-541

To determine the role of mangroves for fisheries in the arid region of the Persian Gulf, we investigated fish community structure and trophic diversity in intertidal creeks with and without mangroves. Fish community abundances and biomass were compared across habitats and seasons. To identify variations in overall community trophic niches among habitats and seasons, we measured niches with size-corrected standard ellipse areas (SEA_c) calculated from C and N stable isotope values. Although there was a slightly greater species richness occurred in mangrove creeks, we found a general similarity in the diversity patterns in creeks with and without mangroves. Also, there were no consistent differences in fish abundance or biomass for mangrove vs. non-mangrove fish collections. Community trophic diversity measured as SEA_c also showed no significant difference between mangrove and non-mangrove sites. Instead, strong seasonal patterns were observed in the fish assemblages. Winter samples had consistently higher fish abundance and biomass than summer samples. Winter SEA_c values were significantly higher, indicating that the fish community had a larger isotopic niche in winter than summer. Overall, we found that seasonality was much stronger than habitat in determining fish community structure and trophic diversity in the mangrove and non-mangrove ecosystems of Qeshm Island, Iran.  相似文献   

The WISERD Geoportal: A Tool for the Discovery,Analysis and Visualization of Socio‐economic (Meta‐) Data for Wales     

Richard Fry  Robert Berry  Gary Higgs  Scott Orford  Sam Jones 《Transactions in GIS》2012,16(2):105-124

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Impacts of gold mine waste disposal on deepwater fish in a pristine tropical marine system     

Brewer DT  Milton DA  Fry GC  Dennis DM  Heales DS  Venables WN 《Marine pollution bulletin》2007,54(3):309-321

Little is known about the impacts of mine waste disposal, including deep-sea tailings, on tropical marine environments and this study presents the first account of this impact on deepwater fish communities. The Lihir gold mine in Papua New Guinea has deposited both excavated overburden and processed tailings slurry into the coastal environment since 1997. The abundances of fish species and trace metal concentrations in their tissues were compared between sites adjacent to and away from the mine. In this study (1999-2002), 975 fish of 98 species were caught. Significantly fewer fish were caught close to the mine than in neighbouring regions; the highest numbers were in regions distant from the mine. The catch rates of nine of the 17 most abundant species were lowest, and in three species were highest, close to the mine. There appears to be limited contamination in fish tissues caused by trace metals disposed as mine waste. Although arsenic (several species) and mercury (one species) were found in concentrations above Australian food standards. However, as in the baseline (pre-mine) sampling, it appears they are accumulating these metals mostly from naturally-occurring sources rather than the mine waste.  相似文献   

Uranus at equinox: Cloud morphology and dynamics     

L.A. Sromovsky  P.M. Fry  W.M. Ahue  K.A. Rages  M.A. van Dam 《Icarus》2009,203(1):265-286

As the 7 December 2007 equinox of Uranus approached, collaboration between ring and atmosphere observers in the summer and fall of 2007 produced a substantial collection of ground-based observations using the 10-m Keck telescope with adaptive optics and space-based observations with the Hubble Space Telescope. Both near-infrared and visible-wavelength imaging and spatially resolved near-infrared spectroscopic observations were obtained. We used observations spanning the period from 7 June 2007 through 9 September 2007 to identify and track cloud features, determine atmospheric motions, characterize cloud morphology and dynamics, and define changes in atmospheric band structure. Atmospheric motions were obtained over a wider range of latitudes than previously was possible, extending to 73°N, and for 28 cloud features we obtained extremely high wind-speed accuracy through extended tracking times. We confirmed the existence of the suspected northern hemisphere prograde jet, locating its peak near 58°N. The new results confirm a small N-S asymmetry in the zonal wind profile, and the lack of any change in the southern hemisphere between 1986 (near solstice) and 2007 (near equinox) suggests that the asymmetry may be permanent rather than seasonally reversing. In the 2007 images, we found two prominent groups of discrete cloud features with very long lifetimes. The one near 30°S has departed from its previous oscillatory motion and started a significant northward drift, accompanied by substantial morphological changes. The complex of features near 30°N remained at a nearly fixed latitude, while exhibiting some characteristics of a dark spot accompanied by bright companion features. Smaller and less stable features were used to track cloud motions at other latitudes, some of which lasted over many planet rotations, though many could not be tracked beyond a single transit. A bright band has developed near 45°N, while the bright band near 45°S has begun to decline, both events in agreement with the idea that the asymmetric band structure of Uranus is a delayed response to solar forcing, but with a surprisingly short delay of only a few years.  相似文献   

Methane on Uranus: The case for a compact CH₄ cloud layer at low latitudes and a severe CH₄ depletion at high-latitudes based on re-analysis of Voyager occultation measurements and STIS spectroscopy     

L.A. Sromovsky  P.M. Fry  J.H. Kim 《Icarus》2011,215(1):292-312

Lindal et al. (Lindal, G.F., Lyons, J.R., Sweetnam, D.N., Eshleman, V.R., Hinson, D.P. [1987]. J. Geophys. Res. 92 (11), 14987-15001) presented a range of temperature and methane profiles for Uranus that were consistent with 1986 Voyager radio occultation measurements of refractivity versus altitude. A localized refractivity slope variation near 1.2 bars was interpreted to be the result of a condensed methane cloud layer. However, models fit to near-IR spectra found particle concentrations much deeper in the atmosphere, in the 1.5-3 bar range (Sromovsky, L.A., Irwin, P.G.J., Fry, P.M. [2006]. Icarus 182, 577-593; Sromovsky, L.A., Fry, P.M. [2010]. Icarus 210, 211-229; Irwin, P.G.J., Teanby, N.A., Davis, G.R. [2010]. Icarus 208, 913-926), and a recent analysis of STIS spectra argued for a model in which aerosol particles formed diffusely distributed hazes, with no compact condensation layer (Karkoschka, E., Tomasko, M. [2009]. Icarus 202, 287-309). To try to reconcile these results, we reanalyzed the occultation observations with the He volume mixing ratio reduced from 0.15 to 0.116, which is near the edge of the 0.033 uncertainty range given by Conrath et al. (Conrath, B., Hanel, R., Gautier, D., Marten, A., Lindal, G. [1987]. J. Geophys. Res. 92 (11), 15003-15010). This allowed us to obtain saturated mixing ratios within the putative cloud layer and to reach above-cloud and deep methane mixing ratios compatible with STIS spectral constraints. Using a 5-layer vertical aerosol model with two compact cloud layers in the 1-3 bar region, we find that the best fit pressure for the upper compact layer is virtually identical to the pressure range inferred from the occultation analysis for a methane mixing ratio near 4% at 5°S. This strongly argues that Uranus does indeed have a compact methane cloud layer. In addition, our cloud model can fit the latitudinal variations in spectra between 30°S and 20°N, using the same profiles of temperature and methane mixing ratio. But closer to the pole, the model fails to provide accurate fits without introducing an increasingly strong upper tropospheric depletion of methane at increased latitudes, in rough agreement with the trend identified by Karkoschka and Tomasko (Karkoschka, E., Tomasko, M. [2009]. Icarus 202, 287-309).  相似文献