scholarly journals An Integrated Shadow-Adjusted Snow-Aging Index for Alpine Regions

2020 ◽  
Vol 12 (8) ◽  
pp. 1249
Author(s):  
Haixing Li ◽  
Jinrong Liu ◽  
Xiangxu Bu ◽  
Xuezhi Feng ◽  
Pengfeng Xiao
Keyword(s):  
Snow Cover ◽  
Aging Process ◽  
Field Measurements ◽  
Northwest China ◽  
Analytic Hierarchy ◽  
Alpine Regions ◽  
Aging Index ◽  
Optical Images ◽  
Searching Method ◽  
Steep Slopes

Detecting the variations in snow cover aging over undulating alpine regions is challenging owing to the complex snow-aging process and shadow effect from steep slopes. This study proposes a novel snow-cover status index, namely shadow-adjusted snow-aging index (SASAI), portraying the integrated aging process within the Manas River Basin in northwest China. The Environment Satellites HJ-1A/B optical images and in-field measurements were used during the snow ablation and accumulation periods. The in-field measurements provide a reference for building a candidate library of snow-aging indicators. The representative aging samples for training and validation were obtained using the proposed time-gap searching method combined with the target zones established based on the altitude of snowline. An analytic hierarchy process was used to determine the snow-aging index (SAI) using multiple optimal snow-aging indicators. After correction by the extreme value optimization algorithm, the SASAI was finally corrected for the effects of shading and assessed. This study provides both a flexible algorithm that indicates the characteristics of snow aging and speculation on the causes of the aging process. The separability of the SAI/SASAI and adaptability of this algorithm on multiperiod remote sensing images further demonstrates the applicability of the SASAI to all the alpine regions.

scholarly journals Irrigation Salinity Risk Assessment and Mapping in Arid Oasis, Northwest China

Water ◽  
2018 ◽  
Vol 10 (7) ◽  
pp. 966 ◽  
Author(s):  
Jumeniyaz Seydehmet ◽  
Guang-Hui Lv ◽  
Abdugheni Abliz ◽  
Qing-Dong Shi ◽  
Abdulla Abliz ◽  
...  
Keyword(s):  
Risk Index ◽  
Shallow Groundwater ◽  
Northwest China ◽  
High Elevation ◽  
Analytic Hierarchy ◽  
Environmental Threat ◽  
Total Soluble Salt ◽  
Composite Risk ◽  
Risk Parameters ◽  
Grey Relational

Irrigation salinity is a common environmental threat for sustainable development in the Keriya Oasis, arid Northwest China. It is mainly caused by unreasonable land management and excessive irrigation. The aim of this study was to assess and map the salinity risk distribution by developing a composite risk index (CRI) for seventeen risk parameters from traditional and scientific fields, based on maximizing deviation method and analytic hierarchy process, the grey relational analysis and the Pressure-State-Response (PSR) sustainability framework. The results demonstrated that the northern part of the Shewol and Yeghebagh village has a very high salinity risk, which might be caused by flat and low terrain, high subsoil total soluble salt, high groundwater salinity and shallow groundwater depth. In contrast, the southern part of the Oasis has a low risk of salinity because of high elevation, proper drainage conditions and a suitable groundwater table. This achievement has shown that southern parts of the Oasis are suitable for irrigation agriculture; for the northern area, there is no economically feasible solution but other areas at higher risk can be restored by artificial measures. Therefore, this study provides policy makers with baseline data for restoring the soil salinity within the Oasis.

scholarly journals Retrieval of snow grain size and albedo of Western Himalayan snow cover using satellite data

2011 ◽  
Vol 5 (1) ◽  
pp. 605-653 ◽  
Author(s):  
H. S. Negi ◽  
A. Kokhanovsky
Keyword(s):  
Grain Size ◽  
Snow Cover ◽  
Western Himalaya ◽  
Sensor Data ◽  
Art Theory ◽  
Grain Sizes ◽  
Spectral Bands ◽  
Steep Slopes ◽  
Different Parts ◽  
Good Agreement

Abstract. In the present study we describe the retrievals of snow grain size and spectral albedo (plane and spherical albedo) for Western Himalayan snow cover using Hyperion sensor data. The asymptotic radiative transfer (ART) theory was explored for the snow retrievals. To make the methodology operational only five spectral bands (440, 500, 1050, 1240 and 1650 nm) of Hyperion were used for snow parameters retrieval. The bi-spectral method (440 nm in the visible and 1050/1240 nm in the NIR region) was used to retrieve snow grain size. Spectral albedos were retrieved using satellite reflectances and estimated grain size. A good agreement was observed between retrieved snow parameters and ground observed snow-meteorological conditions. The satellite retrieved grain sizes were compared with field spectroradiometer retrieved grain sizes and close results were found for Lower Himalayan snow. The wavelength 1240 nm was found to be more suitable compared to 1050 nm for grain size retrieval along the steep slopes. The methodology was able to retrieve the spatial variations in snow parameters in different parts of Western Himalaya which are due to snow climatic and terrain conditions of Himalaya. This methodology is of importance for operational snow cover and glacier monitoring in Himalayan region using space-borne and air-borne sensors.

Effect of Soil Depth on the Quantification of Soil Moisture Content Value Estimated from NOAA Satellite Images

2014 ◽  
Vol 567 ◽  
pp. 705-710
Author(s):  
Abdalhaleem A. Hassaballa ◽  
Abdul Nasir Matori ◽  
Helmi Z.M. Shafri
Keyword(s):  
Soil Moisture ◽  
Critical Parameter ◽  
Satellite Images ◽  
Soil Moisture Content ◽  
Soil Depth ◽  
Vegetation Indices ◽  
Field Measurements ◽  
Spatial Estimation ◽  
Optical Images

Soil moisture (MC) is considered as the most significant boundary conditions controlling most of the hydrological cycle’s processes especially over humid areas. However, MC is very critical parameter to measure because of its variability in both space and time. The fluctuation of MC along the soil depth in turn, makes it so difficult to assess from optical satellite techniques. The study aims to produce a rectified satellite’s surface temperature (Ts) in order to enhance the spatial estimation of MC. The study also aims to produce MC estimates from three variable depths of the soil using optical images from NOAA 17 in order to examine the potential of satellite techniques in assessing the MC along the soil depths. The universal triangle (UT) algorithm was used for MC assessment based on Ts, vegetation Indices (VI) and field measurements of MC; which were conducted at variable depths. The study area was divided into three classes according to the nature of surface cover. The resultant MC extracted from the UT method with rectified Ts, produced accuracies of MC ranging from 0.65 to 0.89 when validated with in-situ measured MC at depths 5cm and 10 cm respectively.

Analysis of snow changes in alpine regions with X-band data: electromagnetic analysis and snow cover mapping

2011 ◽  
Author(s):  
B. Ventura ◽  
T. Schellenberger ◽  
C. Notarnicola ◽  
M. Zebisch ◽  
V. Maddalena ◽  
...  
Keyword(s):  
Snow Cover ◽  
Electromagnetic Analysis ◽  
Alpine Regions ◽  
X Band

scholarly journals Retrieval of snow grain size and albedo of western Himalayan snow cover using satellite data

2011 ◽  
Vol 5 (4) ◽  
pp. 831-847 ◽  
Author(s):  
H. S. Negi ◽  
A. Kokhanovsky
Keyword(s):  
Grain Size ◽  
Snow Cover ◽  
Western Himalaya ◽  
Sensor Data ◽  
Art Theory ◽  
Grain Sizes ◽  
Spectral Bands ◽  
Steep Slopes ◽  
Different Parts ◽  
Good Agreement

Abstract. In the present study we describe the retrievals of snow grain size and spectral albedo (plane and spherical albedo) for western Himalayan snow cover using Hyperion sensor data. The asymptotic radiative transfer (ART) theory was explored for the snow retrievals. To make the methodology operational only five spectral bands (440, 500, 1050, 1240 and 1650 nm) of Hyperion were used for snow parameters retrieval. The bi-spectral method (440 nm in the visible and 1050/1240 nm in the NIR region) was used to retrieve snow grain size. Spectral albedos were retrieved using satellite reflectances and estimated grain size. A good agreement was observed between retrieved snow parameters and ground observed snow-meteorological conditions. The satellite retrieved grain sizes were compared with field spectroradiometer retrieved grain sizes and close results were found for lower Himalayan snow. The wavelength 1240 nm was found to be more suitable compared to 1050 nm for grain size retrieval along the steep slopes. The methodology was able to retrieve the spatial variations in snow parameters in different parts of western Himalaya which are due to snow climatic and terrain conditions of Himalaya. This methodology is of importance for operational snow cover and glacier monitoring in Himalayan region using space-borne and air-borne sensors.

scholarly journals Mitigation of surface runoff and erosion impacts on catchment by stone hedgerows

2011 ◽  
Vol 6 (No. 4) ◽  
pp. 153-164 ◽  
Author(s):  
P. Kovář ◽  
D. Vaššová ◽  
M. Hrabalíková
Keyword(s):  
Surface Runoff ◽  
Overland Flow ◽  
Extreme Rainfall ◽  
Field Measurements ◽  
Lower Surface ◽  
Model Parameters ◽  
Contour Lines ◽  
Soil Hydraulic Parameters ◽  
Rainfall Runoff Model ◽  
Steep Slopes

This paper presents the results of a study on the influence of hedgerows on the process of the surface runoff in the experimental catchment Verneřice 1, Ústí n. L. region, the Czech Republic. The influence of hedgerows on the surface runoff was simulated using the KINFIL rainfall-runoff model. The model parameters were assessed from the field measurements of the soil hydraulic parameters, in particular the saturated hydraulic conductivity and sorptivity. The catchment area is characterised by stone hedgerows constructed by land users throughout the past centuries, using stones collected from the adjacent agricultural fields. Presently, the hydraulic properties of these hedgerows reflect the characteristics of the mixture of stones, deposited soil, and vegetation litter, and they are more permeable than soil on the areas between them. Due to this fact, the permeability of the hedgerows produces a higher infiltration and a lower surface runoff. Therefore, the overland flow vulnerability and impact of water erosion decrease if they are situated in parallel to the contour lines system. The model was applied for two scenarios in the catchment – with and without hedgerows – to assess their effects on extreme rainfalls with a short duration. The surface runoff caused by extreme rainfall was simulated in order to show how hedgerows can mitigate the resultant flood and erosion. This paper provides relevant hydrological data and summarises the influence of man-made hedgerows on the overland flow control, i.e. on long and steep slopes surface runoff.

The temperature effects in aging index of asphalt during UV aging process

2015 ◽  
Vol 93 ◽  
pp. 1125-1131 ◽  
Author(s):  
Wenbo Zeng ◽  
Shaopeng Wu ◽  
Jin Wen ◽  
Zongwu Chen
Keyword(s):  
Temperature Effects ◽  
Aging Process ◽  
Uv Aging ◽  
Aging Index

scholarly journals Comparison of traditional and optical grain-size field measurements with SNOWPACK simulations in a taiga snowpack

2015 ◽  
Vol 61 (225) ◽  
pp. 151-162 ◽  
Author(s):  
L. Leppänen ◽  
A. Kontu ◽  
J. Vehviläinen ◽  
J. Lemmetyinen ◽  
J. Pulliainen
Keyword(s):  
Grain Size ◽  
Snow Cover ◽  
Electromagnetic Waves ◽  
Field Measurements ◽  
Scaling Factor ◽  
Field Conditions ◽  
Meteorological Forcing ◽  
Sensing Applications ◽  
Variable Nature ◽  
Snow Microstructure

AbstractKnowledge of snow microstructure is relevant for modelling the physical properties of snow cover and for simulating the propagation of electromagnetic waves in remote-sensing applications. Characterization of the microstructure in field conditions is, however, a challenging task due to the complex, sintered and variable nature of natural snow cover. A traditional measure applied as a proxy of snow microstructure, which can also be determined in field conditions, is the visually estimated snow grain size. Developing techniques also allow measurement, for example, of the specific surface area (SSA) of snow, from which the optical-equivalent grain size can be derived. The physical snow model SNOWPACK simulates evolution of snow parameters from meteorological forcing data. In this study we compare an extensive experimental dataset of measurements of traditional grain size and SSA-derived optical grain size with SNOWPACK simulations of grain-size parameters. On average, a scaling factor of 1.2 is required to match traditional grain-size observations with the corresponding SNOWPACK simulation; a scaling factor of 2.1 was required for the optical equivalent grain size. Standard deviations of scaling factors for the winters of 2011/12 and 2012/13 were 0.36 and 0.42, respectively. The largest scaling factor was needed in early winter and under melting conditions.

scholarly journals A new Snow-SVAT to simulate the accumulation and ablation of seasonal snow cover beneath a forest canopy

2004 ◽  
Vol 50 (169) ◽  
pp. 171-182 ◽  
Author(s):  
Melody J. Tribbeck ◽  
Robert J. Gurney ◽  
Elizabeth M. Morris ◽  
David W. C. Pearson
Keyword(s):  
Solar Radiation ◽  
Snow Cover ◽  
Forest Canopy ◽  
Correlation Coefficients ◽  
Field Measurements ◽  
Radiation Model ◽  
Physically Based ◽  
Boreal Ecosystem ◽  
Snow Model

AbstractA new snow—soil—vegetation—atmosphere transfer (Snow-SVAT) scheme, which simulates the accumulation and ablation of the snow cover beneath a forest canopy, is presented. The model was formulated by coupling a canopy optical and thermal radiation model to a physically based multi-layer snow model. This canopy radiation model is physically based yet requires few parameters, so can be used when extensive in situ field measurements are not available. Other forest effects such as the reduction of wind speed, interception of snow on the canopy and the deposition of litter were incorporated within this combined model, SNOWCAN, which was tested with data taken as part of the Boreal Ecosystem—Atmosphere Study (BOREAS) international collaborative experiment. Snow depths beneath four different canopy types and at an open site were simulated. Agreement between observed and simulated snow depths was generally good, with correlation coefficients ranging between r2 = 0.94 and r2 = 0.98 for all sites where automatic measurements were available. However, the simulated date of total snowpack ablation generally occurred later than the observed date. A comparison between simulated solar radiation and limited measurements of sub-canopy radiation at one site indicates that the model simulates the sub-canopy downwelling solar radiation early in the season to within measurement uncertainty.

scholarly journals Brief Communication: Updated GAMDAM Glacier Inventory over the High Mountain Asia

2018 ◽  
Author(s):  
Akiko Sakai
Keyword(s):  
Snow Cover ◽  
Cloud Cover ◽  
High Mountain ◽  
Glacier Area ◽  
Landsat Images ◽  
Glacier Inventory ◽  
Final Version ◽  
Seasonal Snow ◽  
Steep Slopes ◽  
Seasonal Snow Cover

Abstract. The first version of the Glacier Area Mapping for Discharge from the Asian Mountains (GAMDAM) glacier inventory was the first methodologically consistent glacier inventory covering High Mountain Asia, and it underestimated glacier area because it did not include steep slopes covered with ice or snow and shadowed areas. During the process of revising the GAMDAM glacier inventory, source Landsat images were carefully selected to find images free of shadows, cloud cover, and seasonal snow cover taken from 1990 to 2010. Then, more than 90 % of the glacier area in the final version of the GAMDAM glacier inventory was delineated based on summer Landsat images. The total glacier area was 100,693±15,103 km2 and included 134,770 glaciers using 453 Landsat image scenes.

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