scholarly journals Spatial distribution of debris thickness and melting from remote-sensing and meteorological data, at debris-covered Baltoro glacier, Karakoram, Pakistan

2008 ◽  
Vol 48 ◽  
pp. 49-57 ◽  
Author(s):  
C. Mihalcea ◽  
C. Mayer ◽  
G. Diolaiuti ◽  
C. D’Agata ◽  
C. Smiraglia ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Spatial Distribution ◽  
Energy Balance ◽  
Meteorological Data ◽  
Thickness Distribution ◽  
Global Radiation ◽  
Model Performance ◽  
Thermal Characteristics ◽  
Lateral Moraine ◽  
Balance Study

AbstractA distributed surface energy-balance study was performed to determine sub-debris ablation across a large part of Baltoro glacier, a wide debris-covered glacier in the Karakoram range, Pakistan. The study area is ~124km2. The study aimed primarily at analyzing the influence of debris thickness on the melt distribution. The spatial distribution of the physical and thermal characteristics of the debris was calculated from remote-sensing (ASTER image) and field data. Meteorological data from an automatic weather station at Urdukas (4022ma.s.l.), located adjacent to Baltoro glacier on a lateral moraine, were used to calculate the spatial distribution of energy available for melting during the period 1–15 July 2004. The model performance was evaluated by comparisons with field measurements for the same period. The model is reliable in predicting ablation over wide debris-covered areas. It underestimates melt rates over highly crevassed areas and water ponds with a high variability of the debris thickness distribution in the vicinity, and over areas with very low debris thickness (<0.03 m). We also examined the spatial distribution of the energy-balance components (global radiation and surface temperature) over the study area. The results allow us to quantify, for the study period, a meltwater production of 0.058 km3.

scholarly journals REMOTE SENSING OF GLOBAL MONTHLY EVAPOTRANSPIRATION WITH AN ENERGY BALANCE (EB) MODEL

2019 ◽  
Vol XLII-2/W13 ◽  
pp. 1729-1733
Author(s):  
X. Chen ◽  
Z. Su ◽  
Y. Ma
Keyword(s):  
Remote Sensing ◽  
Energy Balance ◽  
Land Surface ◽  
Roughness Length ◽  
Meteorological Data ◽  
Global Scale ◽  
Balance Model ◽  
Time Step ◽  
Available Energy ◽  
Hydrological Cycles

<p><strong>Abstract.</strong> A global monthly evapotranspiration (ET) product without spatial-temporal gaps for 2000&amp;ndash;2017 is delivered by using an energy balance (EB) algorithm and MODIS satellite data. It provides us with a moderate resolution estimate of ET without spatial-temporal gaps on a global scale. The model is driven by monthly remote sensing land surface temperature and ERA-Interim meteorological data. A global turbulent exchange parameterization scheme was developed for global momentum and heat roughness length calculation with remote sensing information. The global roughness length was used in the energy balance model, which uses monthly land-air temperature gradient to estimate the turbulent sensible heat, and take the latent heat flux as a residual of the available energy. This study produced an ET product for global landmass, at a monthly time step and 0.05-degree spatial resolution. The performance of ET data has been evaluated in comparison to hundreds flux sites measurements representing a broad range of land covers and climates. The ET product has a mean bias of 3.3&amp;thinsp;mm/month, RMSE value of 36.9&amp;thinsp;mm/month. The monthly ET product can be used to study the global energy and hydrological cycles at either seasonal or inter-annual temporal resolution.</p>

A data-driven approach to quantifying urban evapotranspiration using remote sensing, footprint modeling, and deep learning

2021 ◽  
Author(s):  
Stenka Vulova ◽  
Fred Meier ◽  
Alby Duarte Rocha ◽  
Justus Quanz ◽  
Hamideh Nouri ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Land Surface ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Predictive Accuracy ◽  
Meteorological Data ◽  
Model Performance ◽  
Urban Structure ◽  
Flux Footprint ◽  
Gis Data

&lt;p&gt;An increasing number of urban residents are affected by the urban heat island effect and water scarcity as urbanization and climate change progress. Evapotranspiration (ET) is a key component of urban greening measures aimed at addressing these issues, yet methods to estimate urban ET have thus far been limited. In this study, we present a novel approach to model urban ET at a half-hourly scale by fusing flux footprint modeling, remote sensing (RS) and geographic information system (GIS) data, and artificial intelligence (AI). We investigated this approach with a two-year dataset (2018-2020) from two eddy flux towers in Berlin, Germany. Two AI algorithms (1D convolutional neural networks and random forest) were compared. The land surface characteristics contributing to ET measurements were estimated by combining footprint modeling with RS and GIS data, which included Normalized Difference Vegetation Index (NDVI) derived from the Harmonized Landsat and Sentinel-2 (HLS) NASA product and indicators of 3D urban structure (e.g. building height). The contribution of remote sensing and meteorological data to model performance was examined by testing four predictor scenarios: (1) only reference evapotranspiration (ETo), (2) ETo and RS/ GIS data, (3) meteorological data, and (4) meteorological and RS/ GIS data. The inclusion of GIS and RS data extracted using flux footprints improved the predictive accuracy of models. The best-performing models were then used to model ET values for the year 2019 and compute monthly and annual sums of ET. A variable importance analysis highlighted the importance of the NDVI and impervious surface fraction in modeling urban ET. The 2019 ET sum was considerably higher at the site surrounded by more urban vegetation (366 mm) than at the inner-city site (223 mm). The proposed method is highly promising for modeling ET in a heterogeneous urban environment and can bolster sustainable urban planning efforts.&lt;/p&gt;

scholarly journals Relative performance of empirical and physical models in assessing the seasonal and annual glacier surface mass balance of Saint-Sorlin Glacier (French Alps)

2018 ◽  
Vol 12 (4) ◽  
pp. 1367-1386 ◽  
Author(s):  
Marion Réveillet ◽  
Delphine Six ◽  
Christian Vincent ◽  
Antoine Rabatel ◽  
Marie Dumont ◽  
...  
Keyword(s):  
Energy Balance ◽  
Mass Balance ◽  
Meteorological Data ◽  
Model Performance ◽  
Surface Mass Balance ◽  
Glacier Surface ◽  
Meteorological Forcing ◽  
Surface Mass ◽  
French Alps

Abstract. This study focuses on simulations of the seasonal and annual surface mass balance (SMB) of Saint-Sorlin Glacier (French Alps) for the period 1996–2015 using the detailed SURFEX/ISBA-Crocus snowpack model. The model is forced by SAFRAN meteorological reanalysis data, adjusted with automatic weather station (AWS) measurements to ensure that simulations of all the energy balance components, in particular turbulent fluxes, are accurately represented with respect to the measured energy balance. Results indicate good model performance for the simulation of summer SMB when using meteorological forcing adjusted with in situ measurements. Model performance however strongly decreases without in situ meteorological measurements. The sensitivity of the model to meteorological forcing indicates a strong sensitivity to wind speed, higher than the sensitivity to ice albedo. Compared to an empirical approach, the model exhibited better performance for simulations of snow and firn melting in the accumulation area and similar performance in the ablation area when forced with meteorological data adjusted with nearby AWS measurements. When such measurements were not available close to the glacier, the empirical model performed better. Our results suggest that simulations of the evolution of future mass balance using an energy balance model require very accurate meteorological data. Given the uncertainties in the temporal evolution of the relevant meteorological variables and glacier surface properties in the future, empirical approaches based on temperature and precipitation could be more appropriate for simulations of glaciers in the future.

scholarly journals Relative performance of empirical and physical models in assessing seasonal and annual glacier surface mass balance in the French Alps

2017 ◽  
Author(s):  
Marion Réveillet ◽  
Delphine Six ◽  
Christian Vincent ◽  
Antoine Rabatel ◽  
Marie Dumont ◽  
...  
Keyword(s):  
Energy Balance ◽  
Mass Balance ◽  
Meteorological Data ◽  
Model Performance ◽  
Surface Mass Balance ◽  
Glacier Surface ◽  
Meteorological Forcing ◽  
Surface Mass ◽  
The Future

Abstract. This study focuses on simulations of the seasonal and annual surface mass balance (SMB) of Saint-Sorlin Glacier (French Alps) for the period 1996-2015 using the detailed SURFEX/ISBA-Crocus snowpack model. The model is forced by SAFRAN meteorological reanalysis data, adjusted with AWS measurements to ensure that simulations of all the energy balance components, in particular turbulent fluxes, are accurately represented with respect to the measured energy balance. Results indicate good model performance for the simulation of summer SMB when using meteorological forcing adjusted with in-situ measurements. Model performance however strongly decreases without in-situ meteorological measurements. The sensitivity of the model to meteorological forcing indicates a strong sensitivity to wind speed, higher than the sensitivity to ice albedo. Compared to an empirical approach, the model exhibited better performance for simulations of snow and firn melting in the accumulation area and similar performance in the ablation area when forced with meteorological data adjusted with nearby AWS measurements. When such measurements were not available close to the glacier, the empirical model performed better. Our results suggest that simulations of the evolution of mass balance in the future using energy balance model required very accurate meteorological data which are not reliable from the climatic scenarios. With the current status of knowledge on meteorological variables and glacier surface roughness in the future, empirical approaches based on temperature and precipitation could be more appropriate for simulations of glaciers in the future.

scholarly journals Estimativa do Albedo Comparando Metodologias de Correção Atmosférica em Áreas de Cana-de-Açúcar e Cerrado na Bacia do Rio Mogi Guaçú-SP (Estimation of albedo comparing methodologies of atmospheric correction in areas of sugarcane and cerrado in the ...)

2016 ◽  
Vol 9 (6) ◽  
pp. 1943
Author(s):  
Maurílio Neemias Santos ◽  
Laurizio Emanuel Ribeiro Alves ◽  
Ismael Guidson Farias De Freitas ◽  
Eridiany Ferreira Da Silva ◽  
Heliofabio Barros Gomes
Keyword(s):  
Remote Sensing ◽  
Energy Balance ◽  
Surface Energy ◽  
Surface Energy Balance ◽  
Meteorological Data ◽  
Plant Cover ◽  
Atmospheric Correction ◽  
Sao Paulo ◽  
The State ◽  
São Paulo

O uso de técnicas de sensoriamento remoto nos últimos anos tem se tornado cada vez mais constante nas pesquisas sobre a cobertura vegetal, direcionando as mais variadas aplicações, principalmente quando se deseja analisar e identificar padrões de alteração no local estudado de forma clara e objetiva, visando assim obter maior conhecimento em áreas de difícil acesso. A eficiência na obtenção de dados gera resultados confiáveis principalmente com relação a dados meteorológicos com um baixo custo. O presente trabalho teve como objetivo a obtenção do albedo da superfície com base em imagens do TM Landsat5 e alguns dados meteorológicos obtidos através de estações micrometeorológicas em situ. A área de estudo está localizada no estado de São Paulo, na região da bacia do rio Mogi-Guaçu, município de Santa Rita do Passa Quatro, no estado de São Paulo (21°37’09”S; 47°37’56”W; 710 m). Foram utilizadas oito imagens TM - Landsat5 do ano de 2005 para os dias 22/02, 11/04, 29/05, 14/06, 16/07, 01/08, 17/08, 21/11. Foram empregados os procedimentos do Surface Energy Balance Algorithm for Land (SEBAL) proposto por Bastiaanssen (1995) aprimorados por Allen et al. (2007a) e Tasumi (2006) para obtenção do albedo superficial.    A B S T R A C T The use of remote sensing techniques in recent years has become increasingly constant in research on plant cover, directing the most varied applications, especially when it is desired to analyze and identify patterns of change in the studied area in a clear and objective way, aiming to Knowledge in areas of difficult access. The efficiency in obtaining data generates reliable results mainly in relation to meteorological data with a low cost. The present study had as objective to analyze the albedo of the surface based on images of TM Landsat5 and some meteorological data obtained through micrometeorological stations in situ. The study area is located in the state of São Paulo, in the region of the Mogi-Guaçu river basin, municipality of Santa Rita do Passa Quatro, in the state of São Paulo (21°37’09”S; 47°37’56”W; 710 m). Eight TM - Landsat5 images from the year 2005 were used for the days 22/02, 11/04, 29/05, 14/06, 16/07, 01/08, 17/08, 21/11. The procedures of Surface Energy Balance Algorithm for Land (SEBAL) and superficial albedo of different authors were used. Estimates of the atmospheric correction showed that the albedo of the cerrado presents values inferior to the one found on sugarcane and other areas of the basin, except for water bodies. The different methods discussed in this study showed that the Idaho method presented the best results in the estimation when compared to pyranometric measurements presenting Relative Error lower than the methods presented here.   Keywords: Remote sensing, albedo, Landsat 5. 

scholarly journals Remote Sensing Based Estimation of Evapo-Transpiration Using Selected Algorithms: The Case of Wonji Shoa Sugar Cane Estate, Ethiopia

2016 ◽  
Author(s):  
Mulugeta Genanu ◽  
Tena Alamirew ◽  
Gabriel Senay ◽  
Mekonnen Gebremichael
Keyword(s):  
Remote Sensing ◽  
Energy Balance ◽  
Surface Energy ◽  
Large Scale ◽  
Surface Energy Balance ◽  
Meteorological Data ◽  
Wet Season ◽  
Spatially Distributed ◽  
Spatio Temporal ◽  
Water Surplus

Remote sensing datasets are increasingly being used to provide spatially explicit large scale evapotranspiration (ET) estimates. The focus of this study was to estimate and thematically map pixel-by-pixel basis, and compare the actual evapotranspiration (ETa) of the Wonji Shoa Sugarcane Estate using Surface Energy Balance Algorithm for Land (SEBAL), Simplified Surface Energy Balance (SSEB) and Operational Simplified Surface Energy Balance (SSEBop) algorithms on Landsat7 ETM+ images acquired on four days in 2002. The algorithms were based on image processing which uses spatially distributed spectral satellite data and ground meteorological data to derive the surface energy balance components. The results obtained revealed that the ranges of the daily ETa estimated on January 25, February 26, September 06 and October 08, 2002 using SEBAL were 0.0&ndash;6.85, 0.0&ndash;9.36, 0.0&ndash;3.61, 0.0&ndash;6.83 mm/day; using SSEB 0.0&ndash;6.78, 0.0&ndash;7.81, 0.0&ndash;3.65, 0.0&ndash;6.46 mm/day, and SSEBop were 0.05&ndash;8.25, 0.0&ndash;8.82, 0.2&ndash;4.0, 0.0&ndash;7.40 mm/day, respectively. The Root Mean Square Error (RMSE) values between SSEB and SEBAL, SSEBop and SEBAL, and SSEB and SSEBop were 0.548, 0.548, and 0.99 for January 25, 2002; 0.739, 0.753, and 0.994 for February 26, 2002;0.847, 0.846, and 0.999 for September 06, 2002; 0.573, 0.573, and 1.00 for October 08, 2002, respectively. The standard deviation of ETa over the sugarcane estate showed high spatio-temporal variability perhaps due to soil moisture variability and surface cover. The three algorithm results showed that well watered sugarcane fields in the mid-season growing stage of the crop and water storage areas had higher ETa values compared with the other dry agricultural fields confirming that they consumptively use more water. Generally during the dry season ETa is limited to water surplus areas only and in wet season, ETa was high throughout the entire sugarcane estate. The evaporation fraction (ETrF) results also followed the same pattern as the daily ETa over the sugarcane estate. The total crop and irrigation water requirement and effective rainfall estimated using the Cropwat model were 2468.8, 2061.6 and 423.8 mm/yr for January 2001 planted and 2281.9, 1851.0 and 437.8 mm/yr for March 2001 planted sugarcanes, respectively. The mean annual ETa estimated for the whole estate were 107 Mm3, 140 Mm3, and 178 Mm3 using SEBAL, SSEB, and SSEBop, respectively. Even though the algorithms should be validated through field observation, they have potential to be used for effective estimation of ET in the sugarcane estate.

Estimation and Analysis of Regional Evapotranspiration in the eastern province of China with Remote Sensing data

2020 ◽  
Author(s):  
Wenyu Wu
Keyword(s):  
Remote Sensing ◽  
Energy Balance ◽  
Surface Energy ◽  
Land Surface ◽  
Surface Energy Balance ◽  
Meteorological Data ◽  
Computation Method ◽  
Model Parameters ◽  
Sebal Model ◽  
Regional Evapotranspiration

&lt;p&gt;Evapotranspiration(ET) is a critical component of the land surface energy balance system and hydrologic processes. Analysis of spatiotemporal variations and influencing factors of ET is of great importance to evaluate the growing environment for crops and to effectively use water resources, a critical base for production in research region. The traditional methods are based on point measurement, while the remote sensing provides extensive surface information. The development of remote sensing has promoted the study of regional ET.SEBAL model is based on Surface Energy Balance Algorithm for Land and its physical meaning is clear. This model was developed to show the spatial variability of surface evapotranspiration. SEBAL model was capable of being applied to large regional areas in conjunction with Moderate-resolution Imaging Spectroradiometer (MODIS) data products.According to the shortcomings of the traditional method of calculating ET, based on SEBAL model, the daily regional evapotranspiration of Anhui Province was estimated with 1km spatial resolution by using MODIS products and a few of meteorological data(temperature, wind speed) collected in meteorological stations distributed over the study area.Because of lacking observed data from the lysimeter, the results of P-M were compared with the estimation results based on SEBAL model in this research.The comparison of the evapotranspiration estimated with MODIS products and field observation showed that the former results were lower than the latter results on the whole, and demonstrated that there existed certain trend in correlation between the two results, the average relative error was different at different land surface.The ET computation method based on Remote Sensing proves that this model has strong practicality in Anhui, and it will show great potential in this field with more optimizing the model parameters.&lt;/p&gt;

scholarly journals Research on evaporation of Taiyuan basin area by using remote sensing

2005 ◽  
Vol 2 (1) ◽  
pp. 209-227 ◽  
Author(s):  
X. Jin ◽  
L. Wan ◽  
Z. Su
Keyword(s):  
Remote Sensing ◽  
Spatial Distribution ◽  
Energy Balance ◽  
Surface Energy ◽  
Land Surface ◽  
Surface Energy Balance ◽  
Remote Sensing Data ◽  
Sensing Data ◽  
Taiyuan Basin ◽  
Basin Area

Abstract. Taiyuan basin is enclosed by hills and mountains, located in the middle of Shanxi province, standing between longitudes 111°40'–113°00'E and latitude 37°00'–38&amp;deg00'N. With various types and wide distribution, the mineral resources are very abundant in this basin area. However, there is a great shortage of water resources. Due to continual fall of groundwater level caused by excessive extraction of ground water, some severe environmental problems are induced in this area, such as ground subsidence, etc. The goal of this paper is to estimate the spatial distribution of actual evaporation over the basin by using remote sensing data. The Surface Energy Balance System (SEBS) has been developed (Su, 2001, 2002). Using visible and infrared satellite remote sensing data, SEBS is based on land surface energy balance theory combined with the in-situ meteorological data or the product of atmospheric numerical model to estimate land surface turbulent flux and the relative evaporation at different scales. SEBS was served as the core methodology of this paper and was used for evaporation estimation. On the basis of hydro-geological data and NOAA satellite data, the SEBS was used in this paper for the estimation of actual evaporation of Taiyuan basin. The spatial distribution of the evaporative fraction and daily evaporation over the basin area was shown. On the other hand, the difference of land surface parameters and evaporation for various target types in the basin area was discussed.

scholarly journals Degree-day modelling of the surface mass balance of Urumqi Glacier No. 1, Tian Shan, China

2010 ◽  
Vol 4 (1) ◽  
pp. 207-232 ◽  
Author(s):  
E. Huintjes ◽  
H. Li ◽  
T. Sauter ◽  
Z. Li ◽  
C. Schneider
Keyword(s):  
Spatial Distribution ◽  
Mass Balance ◽  
Meteorological Data ◽  
Model Performance ◽  
Western China ◽  
Shortwave Radiation ◽  
Small Scale ◽  
Surface Mass Balance ◽  
Surface Mass ◽  
Degree Day

Abstract. A distributed temperature-index melt model including potential shortwave radiation is used to calculate annual mean surface mass balance and the spatial distribution of melt rates on the east branch of Urumqi Glacier No. 1, north-western China. The lack of continuous datasets at higher temporal resolution for various climate variables suggests the application of a degree-day model with only few required input variables. The model is calibrated for a six day period in July 2007, for which daily mass balance measurements and meteorological data are available. Based on point measurements of mass balance, parameter values are optimised running a constrained multivariable function using the simplex search method. To evaluate the model performance, annual mass balances for the period 1987/88–2004/05 are calculated using NCEP/NCAR-Reanalysis data. The modelled values fit the observed mass balance with a correlation of 0.98 and an RMSE of 332 mm w.e. Furthermore, the calculated spatial distribution of melt rates shows an improvement in small-scale variations compared to the simple degree-day approach.

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