Downscaling Landsat-8 land surface temperature maps in diverse urban landscapes using multivariate adaptive regression splines and very high resolution auxiliary data     

Joanna Zawadzka  Ron Corstanje  Jim Harris  Ian Truckell 《International Journal of Digital Earth》2020,13(8):899-914

ABSTRACT

We propose a method for spatial downscaling of Landsat 8-derived LST maps from 100(30?m) resolution down to 2–4?m with the use of the Multiple Adaptive Regression Splines (MARS) models coupled with very high resolution auxiliary data derived from hyperspectral aerial imagery and large-scale topographic maps. We applied the method to four Landsat 8 scenes, two collected in summer and two in winter, for three British towns collectively representing a variety of urban form. We used several spectral indices as well as fractional coverage of water and paved surfaces as LST predictors, and applied a novel method for the correction of temporal mismatch between spectral indices derived from aerial and satellite imagery captured at different dates, allowing for the application of the downscaling method for multiple dates without the need for repeating the aerial survey. Our results suggest that the method performed well for the summer dates, achieving RMSE of 1.40–1.83?K prior to and 0.76–1.21?K after correction for residuals. We conclude that the MARS models, by addressing the non-linear relationship of LST at coarse and fine spatial resolutions, can be successfully applied to produce high resolution LST maps suitable for studies of urban thermal environment at local scales.  相似文献   

Some curious thermomagnetic curves and their interpretation     

Ron Day 《Earth and Planetary Science Letters》1975,27(1):95-100

A study of the thermomagnetic curves of synthetic titanomagnetite powders, heated in air, in non-saturation applied magnetic fields showed that the shape of the curves was related to the magnitude of the applied field, the coercivity of the samples, and the effects of oxidation. The most important result to emerge from this study was the occurrence of reproducible peaks at low temperatures (～100–200°C). The temperature at which the peaks occur was found to increase with increasing coercive force or decreasing applied field. It is suggested that the peaks are the result of the “unblocking” of the magnetization, and should not be confused with thermomagnetic characteristics used to classify ferrites. The “unblocking” temperature is dependent on both the coercive force and the applied magnetic field, as is predicted by most models of thermo-remanent magnetization.  相似文献   

Velocity analysis after migration   总被引：1，自引：0，他引：1  

Ron Silva  Yanghua Wang 《Geophysical Prospecting》2002,50(5):539-545

The double‐square‐root (DSR) equation used in pre‐stack migration is formulated in terms of velocity‐dependent and velocity‐independent terms. The velocity‐dependent term is shown to be the hyperbolic normal moveout (NMO) correction, whereas the velocity‐independent term is related to the recording geometry only. This separation of the velocity‐dependent term offers a means of applying vertical corrections to an initial migration velocity field. Using this concept, procedures are described both for velocity determination and for achieving improved structural imaging.
This decoupling is accurate both for constant‐velocity media and for media whose velocity varies as a function of depth. In media whose velocity varies as a function of both space and depth, a procedure is described for building velocity models through common‐image gather (CIG) stacking following prestack depth migration (PSDM) and time conversion (TC). This so‐called PSDM‐TC stack procedure provides a means of (a) incorporating both vertical and lateral velocity updates into an initial velocity model, (b) obtaining improved structural imaging by using a non‐optimal velocity model for the prestack depth migration, and (c) updating velocity by flattening CIGs and maximizing stack energy. The procedure can be applied to both P‐P wave and P‐SV wave migration.  相似文献   

Reflections on Nigel Thrift's optimism: political strategies to implement his vision     

Ron Johnston   《Geoforum》2002,33(4):421-425

This response to Nigel Thrift's recent paper (2002, Geoforum 33, 291–298) develops two of his points: the need for geography to remain buoyant within school curricula and a potential split of physical from human geography within the universities. I argue that political strategies are necessary for both if geography is to remain the large, intellectually vibrant discipline that Thrift identifies.  相似文献   

Ethnic Residential Segregation Across an Urban System: The Maori in New Zealand, 1991–2001     

Ron Johnston  Michael Poulsen  James Forrest 《The Professional geographer》2005,57(1):115-129

In New Zealand there are substantial variations across the urban system in the degree of residential segregation of those claiming Maori ethnicity. Analyses of those variations, using measures particularly relevant to comparative study, show that Maori segregation was greatest in both 1991 and 2001 in larger urban areas and, especially, in those with relatively large Maori populations. A major deviation from this general pattern was in Auckland; further analysis suggests that this was because of considerable sharing of residential space involving Maori and Pacific Islanders. If the total population claiming a Polynesian identity is studied, the relationships between segregation and both size and Polynesian population share are clarified.  相似文献   

X线和CT对原发支气管癌的诊断价值     

高艳  古晓泉 《CT理论与应用研究》1994,3(1):17-20

本文利用Ｘ线、ＣＴ扫描技术，对原发支气管瘤的各种组织类型在Ｘ线及ＣＴ中的表现进行了观察，分析了其位置、大小、边缘、钙化、空洞和转移情况，阐明了胸部ＣＴ是肺癌时诊断肺门和纵隔侵犯的更佳方法，较Ｘ线有很大优越性。Ｘ线和ＣＴ相结合对原发支气管癌的定性诊断具有重要价值。  相似文献   

The intermediate-wavelength magnetic anomaly maps of the North Atlantic Ocean derived from satellite and shipborne data     

Jafar Arkani-Hamed  Jacob Verhoef  Walter Roest  Ron Macnab 《Geophysical Journal International》1995,123(3):727-743

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Modern and post-modern cities and ethnic residential segregation: Is Los Angeles different?   总被引：1，自引：0，他引：1  

Ron Johnston  Michael Poulsen 《Geoforum》2006,37(3):318-330

Dear and others associated with the ‘Los Angeles School of Urbanism’ have presented a series of challenging ideas regarding changes in urban form as a consequence of the shift from modernism to post-modernism. Some of those challenges relate to a city’s ethnic diversity and residential segregation, with Los Angeles presented as a paradigm exemplar of an emerging new urban form. This paper evaluates the arguments that Los Angeles in particular, and Californian metropolitan areas more generally, differ from metropolitan areas elsewhere in the United States in the nature of ethnic residential segregation there. Regression analyses provide little support for the argument, but graphical analyses show that although Los Angeles does not differ from the general, US-wide trends, its almost unique nature in terms of its ethnic diversity means that it clearly stands out as a place with a different pattern shared by very few others.  相似文献   

Short Note: On the Relativistic Doppler Effect for Precise Velocity Determination using GPS     

Jason Zhang  Kefei Zhang  Ron Grenfell  Rod Deakin 《Journal of Geodesy》2006,80(2):104-110

The Doppler effect is the apparent shift in frequency of an electromagnetic signal that is received by an observer moving relative to the source of the signal. The Doppler frequency shift relates directly to the relative speed between the receiver and the transmitter, and has thus been widely used in velocity determination. A GPS receiver-satellite pair is in the Earth’s gravity field and GPS signals travel at the speed of light, hence both Einstein’s special and general relativity theories apply. This paper establishes the relationship between a Doppler shift and a user’s ground velocity by taking both the special and general relativistic effects into consideration. A unified Doppler shift model is developed, which accommodates both the classical Doppler effect and the relativistic Doppler effect under special and general relativities. By identifying the relativistic correction terms in the model, a highly accurate GPS Doppler shift observation equation is presented. It is demonstrated that in the GPS “frequency” or “velocity” domain, the relativistic effect from satellite motion changes the receiver-satellite line-of-sight direction, and the measured Doppler shift has correction terms due to the relativistic effects of the receiver potential difference from the geoid, the orbit eccentricity, and the rotation of the Earth.  相似文献   

A coarse-grained basin floor turbidite system – the Jurassic Los Molles Formation,Neuquen Basin,Argentina     

Gabriel Giacomone  Cornel Olariu  Ron Steel  Moonsoo Shin 《Sedimentology》2020,67(7):3809-3843

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