Estimating Exposure Roughness Based on Google Earth

Yu, Jianhan; Stathopoulos, T.; Li, Mingshui

doi:10.1061/(asce)st.1943-541x.0002913

Cited by 7 publications

(5 citation statements)

References 46 publications

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“…To evaluate the slopes across the escarpments, we generated elevation profiles at 5 km intervals along each escarpment and determined the maximal slope for a perpendicular transect over a 1–5 km distance across the escarpment. We estimated maximal slopes using Google Earth Engine (Gorelick et al, 2017 ), which provides accurate estimates of slope comparable to GIS but with more efficient deployment (Safanelli et al, 2020 ; Yu et al, 2021 ). For the Manyara‐Natron escarpment, the 0 km elevation profile transect (EPT) was located in Kenya at 1°15′08.11″S 35°59′41.71″E and the 400 km terminal EPT was located in Tanzania at 4°42′54.32″S 35°56′59.97″E.…”

Section: Methodsmentioning

confidence: 99%

“…We estimated maximal slopes using Google Earth Engine (Gorelick et al, 2017), which provides accurate estimates of slope comparable to GIS but with more efficient deployment (Safanelli et al, 2020;Yu et al, 2021). For the Manyara-Natron escarpment, the 0 km elevation profile transect (EPT) was located in Kenya at 1°15′08.11″S…”

Section: Dispersal Route Assessmentmentioning

confidence: 99%

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Genetic evidence of population subdivision among Masai giraffes separated by the Gregory Rift Valley in Tanzania

Lohay

Lee

Wu-Cavener

et al. 2023

Ecology and Evolution

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The Masai giraffe has experienced a population decline from 70,000 to 35,000 in the past three decades and was declared an endangered subspecies by the IUCN in 2019. The remaining number of Masai giraffe are geographically separated by the steep cliffs of the Gregory Rift escarpments (GRE) in Tanzania and Kenya dividing them into two populations, one west and one east of the GRE. The cliffs of the GRE are formidable barriers to east–west dispersal and gene flow and the few remaining natural corridors through the GRE are occupied by human settlements. To assess the impact of the GRE on Masai giraffe gene flow, we examined whole genome sequences of nuclear and mitochondrial DNA (mtDNA) variation in populations located east (Tarangire ecosystem) and west (Serengeti ecosystem) of the GRE in northern Tanzania. Evidence from mtDNA variation, which measures female‐mediated gene flow, suggests that females have not migrated across the GRE between populations in the Serengeti and Tarangire ecosystems in the past ~289,000 years. The analysis of nuclear DNA variation compared to mtDNA DNA variation suggests that male‐mediated gene flow across the GRE has occurred more recently but stopped a few thousand years ago. Our findings show that Masai giraffes are split into two populations and fulfill the criteria for designation as distinct evolutionary significant units (ESUs), which we denote as western Masai giraffe and eastern Masai giraffe. While establishing giraffe dispersal corridors across the GRE is impractical, conservation efforts should be focused on maintaining connectivity among populations within each of these two populations. The importance of these efforts is heightened by our finding that the inbreeding coefficients are high in some of these Masai giraffe populations, which could result in inbreeding depression in the small and fragmented populations.

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Section: Methodsmentioning

confidence: 99%

Section: Dispersal Route Assessmentmentioning

confidence: 99%

Genetic evidence of population subdivision among Masai giraffes separated by the Gregory Rift Valley in Tanzania

Lohay

Lee

Wu-Cavener

et al. 2023

Ecology and Evolution

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“…The intent is to allow interpolation in exposure transition zones near changes in ground surface roughness. In another study (Yu et al, 2019), a different approach based on the details of the upstream exposure identifies the particular directional roughness length leading to the appropriate exposure factor more expeditiously and accurately.…”

Section: Terrain Factormentioning

confidence: 99%

Wind loads on buildings: A code of practice perspective

Stathopoulos

Alrawashdeh

2020

Journal of Wind Engineering and Industrial Aerodynamics

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“…(3) micrometeorological methods (Grimmond & Oke, 1999;He et al, 2017;Kent et al, 2017;Yu et al, 2021). In general, micrometeorological methods are deemed preferable to determining the aerodynamic parameters because of their high accuracy.…”

Section: Introductionmentioning

confidence: 99%

“…Unfortunately, these parameters are not often documented along with meteorological observation records, so they must be determined separately. The existing methods used to determine

{z}_0

can be categorized into three groups: (1) reference‐based methods, (2) morphometric methods, and (3) micrometeorological methods (Grimmond & Oke, 1999; He et al, 2017; Kent et al, 2017; Yu et al, 2021). In general, micrometeorological methods are deemed preferable to determining the aerodynamic parameters because of their high accuracy.…”

Section: Introductionmentioning

confidence: 99%

Investigation of exposure correction models for wind speed measurements

Zhao

Fang

2022

Meteorological Applications

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Considerable errors may be introduced in storm intensity estimations and their subsequent applications if raw surface wind speed records are not corrected to properly account for exposure effects. This study investigates the calculation of exposure correction factors (ECFs) by different theoretical and code-based models. Estimation of the roughness length z 0 based on the suitable gustiness model is provided, as this metric is involved in calculating ECFs. The sensitivity of the z 0 estimation to the input parameters is analysed. A comprehensive evaluation of ECF models is made, which includes the World Meteorological Organization (WMO) model with various blending heights z b , Biétry model, the power-law model, the Engineering Sciences Data Unit model, the models in Chinese, Japanese, Eurocode and the International Organization for Standardization codes, as well as the combination of the WMO formula with two gustiness models (He model and Ashcroft model) respectively. It is found that the most appropriate model in practice for calculating ECFs is provided by the combined application of the He gustiness model and WMO ECF formula with a blending height, z b , of 80m.

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Estimating Exposure Roughness Based on Google Earth

Cited by 7 publications

References 46 publications

Genetic evidence of population subdivision among Masai giraffes separated by the Gregory Rift Valley in Tanzania

Genetic evidence of population subdivision among Masai giraffes separated by the Gregory Rift Valley in Tanzania

Wind loads on buildings: A code of practice perspective

Investigation of exposure correction models for wind speed measurements

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