The-Seychelles Bank and Madagascar Shelf in the western Indian Ocean were explored geologically during a cruise of the R/V "professor Shtokman" in 1986. Using the data of relief, sediment characteristics and...The-Seychelles Bank and Madagascar Shelf in the western Indian Ocean were explored geologically during a cruise of the R/V "professor Shtokman" in 1986. Using the data of relief, sediment characteristics and their sequences of strata, paleogeographic maps (18,000 a B.P.) of these areas were produced. These maps show that the Bank and the Shelf are carbonate platforms with complicated topography. The data indicate an important role of sea level oscillation in relief development of this area.展开更多
Temperature and water flow through a culvert beneath the Alaska Highway near Beaver Creek,Yukon,were measured at hourly intervals between June and October 2013.These data were used to simulate the effect of the culver...Temperature and water flow through a culvert beneath the Alaska Highway near Beaver Creek,Yukon,were measured at hourly intervals between June and October 2013.These data were used to simulate the effect of the culvert on the thermal regime of the road embankment and subjacent permafrost.A 2-D thermal model of the embankment and permafrost was developed with TEMP/W and calibrated using field observations.Empirical relations were obtained between water temperatures at the entrance to the culvert,flow into the culvert,and water temperatures inside the structure.Water temperatures at the entrance and inside the culvert had a linear relation,while water temperatures inside the culvert and water flow were associated by a logarithmic relation.A multiple linear regression was used to summarize these relations.From this relationship,changes in the flow rate and water temperatures at the entrance of the culvert were simulated to obtain predicted water temperatures in the culvert.The temperatures in the culvert were used in the thermal model to determine their effects on the ground thermal regime near the culvert.Variation of ±10% in water flow rate had no impact on the thermal regime underneath the culvert.Variation of water temperature at the entrance of the culvert had a noticeable influence on the thermal regime.A final simulation was conducted without insulation beneath the culvert.The thaw depth was 30 cm with insulation,and 120 cm without insulation,illustrating the importance of insulation to the ground thermal regime.展开更多
The concentration of cosmogenic loBe in riverine sediments has been widely used as a proxy for catchment-wide denudation rate （CWDR）. One of the key assumptions of this approach is that sediments originating from su...The concentration of cosmogenic loBe in riverine sediments has been widely used as a proxy for catchment-wide denudation rate （CWDR）. One of the key assumptions of this approach is that sediments originating from sub-basins with different erosional histories are well mixed. A tragic debris flow occurred in the Seti River watershed, central Nepal, on May 5, 2012. This catastrophic debris flow was triggered by slope failure on the peak of Annapurna IV and resulted in many casualties in the lower Seti Khola. However, it provided an opportunity to test the assumption of equal mixing of sediments in an understudied rapidly eroding watershed. This study documents the CWDR of ^10Be to evaluate the extent of the influence of episodic erosional processes such as debris flow on the spatio-temporal redistribution of loBe concentrations. Our data show that the debris flow caused little change in CWDR across the debris flow event. In addition to isotopic measurement, we calculated denudation rates by using the modeled concentrations in pre- and post-landslide sediments based on the local ^10Be production rate. The modeled result showed little change across the event, indicating that the debris flow in May 2012 played a minor role in sediment evacuation, despite the rapid erosion in the catchment. Our study concludes that although the 2012 event caused many casualties and severe damage, it was a low-magnitude, high frequency event.展开更多
This article examines integration vs. segregation of Arabs in Israel＇s social sphere. Most geo-spatial studies regarding inter-ethnic relations are single dimensional, focusing on residential segregation assuming its...This article examines integration vs. segregation of Arabs in Israel＇s social sphere. Most geo-spatial studies regarding inter-ethnic relations are single dimensional, focusing on residential segregation assuming its association to the social domain. We argue that in the globalizing world daily activity spaces, social networks and influences on everyday life conditions are rooted in growing horizons around residential location weakening the power of residential location to dictate life conditions. Hence we suggest employing a multi-dimensional approach. Specifically, we explore the associations among residential spaces （relating to Arab residents of： purely Arab localities; mixed-Jewish-Arab cities, and Jewish cities）; main activity spaces （commuters to Jewish areas and localists--people staying mostly in the Arab localities） and social integration （social networks; repertoire of identities; attitudes toward integration and knowledge of Hebrew）. The data incorporate tracking the movements of 177 responders for a week （using a GPS logger） and in-depth interviews, which were analyzed quantitatively. Core findings suggest that both residential place and activity spaces affect social integration, however, the locality type has a greater affect. In addition, we identified four integration sorts according to kinds of municipality, activity spaces, and integration measures： （1） segregated localists living in Arab municipalities; （2） commuters living in Arab localities characterized by limited integration; （3） Arabs residing in Jewish cities that succeeded economically but are characterized by limited social integration, and （4） those living in mixed cities which enjoy the highest, yet limited integration level.展开更多
Previous studies have shown evidence of atmospheric extratropical wave trains modulating sea ice area in the Weddell and Amundsen/Bellingshausen seas on intraseasonal time-scales(20–100 d). Here we investigate mechan...Previous studies have shown evidence of atmospheric extratropical wave trains modulating sea ice area in the Weddell and Amundsen/Bellingshausen seas on intraseasonal time-scales(20–100 d). Here we investigate mechanisms relating intraseasonal extreme sea ice extent and Ekman layer dynamics with emphasis on the Weddell Sea. This study extends from 1989 to 2013 and focuses on the winter season. Wind stress τ is calculated with winds from the Climate Forecast System reanalysis(CFSR) to evaluate momentum transfer between the atmosphere and the Ekman layer. Lag-composites of the anomalies of Ekman transport and the Ekman pumping indicate that divergence of mass in the Ekman layer and upwelling lead the occurrence of extreme sea ice contraction on intraseasonal time-scales in the Weddell Sea. Opposite conditions(i.e., convergence of the mass and downwelling) lead extreme sea ice expansion on intraseasonal time-scales. This study suggests that the Ekman pumping resulting from the anomalous wind stress on intraseasonal time-scales can transport these warmer waters to the surface contributing to sea ice melting. Additionally, high resolution sea ice fraction and ocean currents obtained from satellite and in situ data are used to investigate in detail mechanisms associated with persistent extreme sea ice expansion and contraction on intraseasonal time-scales. These case studies reveal that atmospheric circumpolar waves on intraseasonal time-scales can induce contrasting anomalies of about ±20% in sea ice concentration at the Weddell and western Antarctica Peninsula margins within less than 30 d. This study shows that extreme anomalies in sea ice may lag between 5–25 d(1–5 pentads) the ocean-atmospheric forcing on intraseasonal time-scales.展开更多
The study of the spatial patterns and temporal changes of cropland is important to understand the underlying factors and the functional effects of the agricultural landscape. On the other hand, crop dynamics mapping i...The study of the spatial patterns and temporal changes of cropland is important to understand the underlying factors and the functional effects of the agricultural landscape. On the other hand, crop dynamics mapping is essential to know the overall agro-spatial diversity of the area. Therefore, this paper addressed a spatio-temporal analysis of cropland and cropping pattern change in the Bogra district of Bangladesh over the last 16 years （between 1988/89 and 2004/05）. In this paper, crop mapping from multi-temporal and multi-sensor satellite images was described. Landsat TM and IRS P6 LlSS Ⅲ satellite images were used with GIS for spatial dynamics of cropland and cropping pattern change analysis. First, seasonal cropland maps were derived from object-based classification of satellite images, then two-date classified image differencing with GIS overlay technique and decision rules were applied. Cropping pattern change was analyzed in a spatial and quantitative way for the 16 years and for this, Integrated Land and Water Information System （ILWIS） and Land Change Modular （LCM） of IDRISl Andes were used. The results showed that in the area, mono crop cultivation was found in summer, but in winter, areas under different crop cultivation had changed dramatically. Change analysis showed that the changes mainly occurred in the north northwest and southwest of the areas, and during the time the highest change area was found under the rice-potato pattern.展开更多
<正> The Qaidam Basin is a larger sedimentary basin in western China where the thickness of the Quaternary deposits is in the range of 2000-3000 m at its subsiding center. This paper first dates palaeomagnetical...<正> The Qaidam Basin is a larger sedimentary basin in western China where the thickness of the Quaternary deposits is in the range of 2000-3000 m at its subsiding center. This paper first dates palaeomagnetically the cores obtained from the five continuously sampled intervals and those from a typical profile, determineds the age of the index fossil zones, and calculates the deposition rates for the varve deposits based on the sedimentological analysis. As a result, we can calculate the ages of the various characteristic beds (including fossil zones, seismic reflection beds, and marker layers of electrical properties) for any given borehole-section when it was divided into facies, and check the validity of the chronology. According to all those studies, the stratigraphic and geochronologic analysis program of the Quaternary deposits in the Qaidam Basin has permitted a detailed discussion to be made in this paper.展开更多
Present research is an endeavour to scrutinise the spatio-temporal climatic characteristics of tropical cyclones(TCs)bustle in the Bay of Bengal basin,found in RSMC-IMD data all through 1971–2020.A large number of TC...Present research is an endeavour to scrutinise the spatio-temporal climatic characteristics of tropical cyclones(TCs)bustle in the Bay of Bengal basin,found in RSMC-IMD data all through 1971–2020.A large number of TCs,i.e.121 with a decadal average of 35.2 TCs has been examined for the last 50 years where depression(D)and deep depression(DD)have not been taken into account as these are less violent in nature.During the study periods,inter-annual and inter-decadal variation in cyclogenesis,landfall,length,speed,track shape and sinuosity,energy metrics and damage profile have been perceived.The study is clearly showing TCs took the northward track during the pre-monsoon season and made their landfall across the coasts of Bangladesh and Myanmar,while post-monsoon TCs made their landfall directly on the coasts of Orissa and West Bengal.In the post-monsoon phase,VF,ACE and PDI are significantly higher than in the monsoon season in the case of TCs and higher in the pre-monsoon season than in the monsoon season in the case of TCs comparing the energy metrics in different seasons.TC activity is comparatively pronounced during La Niña and El Niño regimes respectively and the genesis position in the BoB is moves to the east(west)of 87°E.During the cold regime,the number of extreme TC above the VSCS category,increased intensely.It is believed that the research findings will help stakeholders of the nation to take accurate strides to combat such violent events with persistent intensification.展开更多
Global climate change,climate extremes,and overuse of natural resources are all major contributors to the risk brought on by cyclones.In I West Bengal state of India,the Pathar Pratima Block frequently experiences a v...Global climate change,climate extremes,and overuse of natural resources are all major contributors to the risk brought on by cyclones.In I West Bengal state of India,the Pathar Pratima Block frequently experiences a variety of risks that result in significant loss of life and livelihood.In order to govern coastal society,it is crucial to measure and map the multi-hazards risk status.To depict the multi-hazards vulnerability and risk status,no cutting-edge models are currently being applied.Predicting distinct physical vulnerabilities is possible using a variety of cutting-edge machine learning techniques.This study set out to precisely describe multi-hazard risk using powerful machine learning methods.This study involved the use of Analytic Hierarchical Analysis and two cutting-edge machine-learning algorithms-Random Forest and Artificial Neural Network,which are yet underutilized in this area.The multi-hazards risk was determined by taking into account six criteria.The southern and eastern regions of the research area are clearly identified by the multi-hazards risk maps as having high to extremely high hazards risk levels.Cyclonic hazards and embankment breaching are the main dominant factors among the multi-hazards.The machine learning approach is the most accurate model for mapping the multi-hazards risk where the ROC result of Random forest and artificial neural network is more than the conventional method AHP.Here RF is the most validated model than the other two.The effectiveness,root mean square error,true skill statistics,Friedman and Wilcoxon rank test,and area under the curve of receiver operating characteristic tests were used to evaluate the prediction capacity of newly constructed models.The RMSE values of 0.24 and 0.26,TSS values of 0.82 and 0.73,and AUC values of 88.20%and 89.10%as produced by RF and ANN models,respectively,were all excellent.展开更多
Earth observations and model simulations are generating big multidimensional array-based raster data.However,it is difficult to efficiently query these big raster data due to the inconsistency among the geospatial ras...Earth observations and model simulations are generating big multidimensional array-based raster data.However,it is difficult to efficiently query these big raster data due to the inconsistency among the geospatial raster data model,distributed physical data storage model,and the data pipeline in distributed computing frameworks.To efficiently process big geospatial data,this paper proposes a three-layer hierarchical indexing strategy to optimize Apache Spark with Hadoop Distributed File System(HDFS)from the following aspects:(1)improve I/O efficiency by adopting the chunking data structure;(2)keep the workload balance and high data locality by building the global index(k-d tree);(3)enable Spark and HDFS to natively support geospatial raster data formats(e.g.,HDF4,NetCDF4,GeoTiff)by building the local index(hash table);(4)index the in-memory data to further improve geospatial data queries;(5)develop a data repartition strategy to tune the query parallelism while keeping high data locality.The above strategies are implemented by developing the customized RDDs,and evaluated by comparing the performance with that of Spark SQL and SciSpark.The proposed indexing strategy can be applied to other distributed frameworks or cloud-based computing systems to natively support big geospatial data query with high efficiency.展开更多
Thirty-nine soils were studied on Holocene and late Pleistocene geomorphic surfaces.Granodiorite, sandstone, and alluvium derived from these rocks are the parent materials. Climateis Mediterranean. Chamise （Adenostom...Thirty-nine soils were studied on Holocene and late Pleistocene geomorphic surfaces.Granodiorite, sandstone, and alluvium derived from these rocks are the parent materials. Climateis Mediterranean. Chamise （Adenostoma faciculatum） is on the drier sites and redwood （Sequoiasempervirens） on the moister sites. Our objectives are twofold, （1） Find if today’s two-season wet-dry, subhumid climate explains the general noncalcic nature of the soils, or if not （2） accept thattheir noncalcic nature results from more moist past climates and define some indicator soilproperties. The depth to carbonate in the soils formed in calcareous materials on Holocenesurfaces corresponds roughly to the average annual depth of water movement, not to the predictedwettest years. We accept then, that the relict paleosols formed under one or more pluvial cyclesbecause they are free of carbonate below their B horizons. Defined levels of pedon clayaccumulation, dithionite-citrate extractable Fe （Fe<sub>d</sub>） accumulation in the B horizons, cationexchange capacity at pH 7 （CEC<sub>7</sub>） to clay ratios, and the minimum base saturation at pH 7 （BS<sub>7</sub>） inthe pedons are useful properties for separating these relict paleosols from the Holocene age soils.A further evidence of the relict nature of the soils on the Pleistocene surfaces is the weatheringreversal noted in these previously weathered materials.展开更多
文摘The-Seychelles Bank and Madagascar Shelf in the western Indian Ocean were explored geologically during a cruise of the R/V "professor Shtokman" in 1986. Using the data of relief, sediment characteristics and their sequences of strata, paleogeographic maps (18,000 a B.P.) of these areas were produced. These maps show that the Bank and the Shelf are carbonate platforms with complicated topography. The data indicate an important role of sea level oscillation in relief development of this area.
基金Transport Canada for financial support and Yukon Highways and Public Works for their support,logistics and assistance during instrumentation at the new Beaver Creek Culvert and information regarding the rules for construction of culverts in Yukon
文摘Temperature and water flow through a culvert beneath the Alaska Highway near Beaver Creek,Yukon,were measured at hourly intervals between June and October 2013.These data were used to simulate the effect of the culvert on the thermal regime of the road embankment and subjacent permafrost.A 2-D thermal model of the embankment and permafrost was developed with TEMP/W and calibrated using field observations.Empirical relations were obtained between water temperatures at the entrance to the culvert,flow into the culvert,and water temperatures inside the structure.Water temperatures at the entrance and inside the culvert had a linear relation,while water temperatures inside the culvert and water flow were associated by a logarithmic relation.A multiple linear regression was used to summarize these relations.From this relationship,changes in the flow rate and water temperatures at the entrance of the culvert were simulated to obtain predicted water temperatures in the culvert.The temperatures in the culvert were used in the thermal model to determine their effects on the ground thermal regime near the culvert.Variation of ±10% in water flow rate had no impact on the thermal regime underneath the culvert.Variation of water temperature at the entrance of the culvert had a noticeable influence on the thermal regime.A final simulation was conducted without insulation beneath the culvert.The thaw depth was 30 cm with insulation,and 120 cm without insulation,illustrating the importance of insulation to the ground thermal regime.
基金supported by the College of Education,Korea University Grant in 2016
文摘The concentration of cosmogenic loBe in riverine sediments has been widely used as a proxy for catchment-wide denudation rate （CWDR）. One of the key assumptions of this approach is that sediments originating from sub-basins with different erosional histories are well mixed. A tragic debris flow occurred in the Seti River watershed, central Nepal, on May 5, 2012. This catastrophic debris flow was triggered by slope failure on the peak of Annapurna IV and resulted in many casualties in the lower Seti Khola. However, it provided an opportunity to test the assumption of equal mixing of sediments in an understudied rapidly eroding watershed. This study documents the CWDR of ^10Be to evaluate the extent of the influence of episodic erosional processes such as debris flow on the spatio-temporal redistribution of loBe concentrations. Our data show that the debris flow caused little change in CWDR across the debris flow event. In addition to isotopic measurement, we calculated denudation rates by using the modeled concentrations in pre- and post-landslide sediments based on the local ^10Be production rate. The modeled result showed little change across the event, indicating that the debris flow in May 2012 played a minor role in sediment evacuation, despite the rapid erosion in the catchment. Our study concludes that although the 2012 event caused many casualties and severe damage, it was a low-magnitude, high frequency event.
基金Acknowledgments The authors thank the ISF-Israeli Science Foundation Bikura program for funding the project.
文摘This article examines integration vs. segregation of Arabs in Israel＇s social sphere. Most geo-spatial studies regarding inter-ethnic relations are single dimensional, focusing on residential segregation assuming its association to the social domain. We argue that in the globalizing world daily activity spaces, social networks and influences on everyday life conditions are rooted in growing horizons around residential location weakening the power of residential location to dictate life conditions. Hence we suggest employing a multi-dimensional approach. Specifically, we explore the associations among residential spaces （relating to Arab residents of： purely Arab localities; mixed-Jewish-Arab cities, and Jewish cities）; main activity spaces （commuters to Jewish areas and localists--people staying mostly in the Arab localities） and social integration （social networks; repertoire of identities; attitudes toward integration and knowledge of Hebrew）. The data incorporate tracking the movements of 177 responders for a week （using a GPS logger） and in-depth interviews, which were analyzed quantitatively. Core findings suggest that both residential place and activity spaces affect social integration, however, the locality type has a greater affect. In addition, we identified four integration sorts according to kinds of municipality, activity spaces, and integration measures： （1） segregated localists living in Arab municipalities; （2） commuters living in Arab localities characterized by limited integration; （3） Arabs residing in Jewish cities that succeeded economically but are characterized by limited social integration, and （4） those living in mixed cities which enjoy the highest, yet limited integration level.
文摘Previous studies have shown evidence of atmospheric extratropical wave trains modulating sea ice area in the Weddell and Amundsen/Bellingshausen seas on intraseasonal time-scales(20–100 d). Here we investigate mechanisms relating intraseasonal extreme sea ice extent and Ekman layer dynamics with emphasis on the Weddell Sea. This study extends from 1989 to 2013 and focuses on the winter season. Wind stress τ is calculated with winds from the Climate Forecast System reanalysis(CFSR) to evaluate momentum transfer between the atmosphere and the Ekman layer. Lag-composites of the anomalies of Ekman transport and the Ekman pumping indicate that divergence of mass in the Ekman layer and upwelling lead the occurrence of extreme sea ice contraction on intraseasonal time-scales in the Weddell Sea. Opposite conditions(i.e., convergence of the mass and downwelling) lead extreme sea ice expansion on intraseasonal time-scales. This study suggests that the Ekman pumping resulting from the anomalous wind stress on intraseasonal time-scales can transport these warmer waters to the surface contributing to sea ice melting. Additionally, high resolution sea ice fraction and ocean currents obtained from satellite and in situ data are used to investigate in detail mechanisms associated with persistent extreme sea ice expansion and contraction on intraseasonal time-scales. These case studies reveal that atmospheric circumpolar waves on intraseasonal time-scales can induce contrasting anomalies of about ±20% in sea ice concentration at the Weddell and western Antarctica Peninsula margins within less than 30 d. This study shows that extreme anomalies in sea ice may lag between 5–25 d(1–5 pentads) the ocean-atmospheric forcing on intraseasonal time-scales.
文摘The study of the spatial patterns and temporal changes of cropland is important to understand the underlying factors and the functional effects of the agricultural landscape. On the other hand, crop dynamics mapping is essential to know the overall agro-spatial diversity of the area. Therefore, this paper addressed a spatio-temporal analysis of cropland and cropping pattern change in the Bogra district of Bangladesh over the last 16 years （between 1988/89 and 2004/05）. In this paper, crop mapping from multi-temporal and multi-sensor satellite images was described. Landsat TM and IRS P6 LlSS Ⅲ satellite images were used with GIS for spatial dynamics of cropland and cropping pattern change analysis. First, seasonal cropland maps were derived from object-based classification of satellite images, then two-date classified image differencing with GIS overlay technique and decision rules were applied. Cropping pattern change was analyzed in a spatial and quantitative way for the 16 years and for this, Integrated Land and Water Information System （ILWIS） and Land Change Modular （LCM） of IDRISl Andes were used. The results showed that in the area, mono crop cultivation was found in summer, but in winter, areas under different crop cultivation had changed dramatically. Change analysis showed that the changes mainly occurred in the north northwest and southwest of the areas, and during the time the highest change area was found under the rice-potato pattern.
文摘<正> The Qaidam Basin is a larger sedimentary basin in western China where the thickness of the Quaternary deposits is in the range of 2000-3000 m at its subsiding center. This paper first dates palaeomagnetically the cores obtained from the five continuously sampled intervals and those from a typical profile, determineds the age of the index fossil zones, and calculates the deposition rates for the varve deposits based on the sedimentological analysis. As a result, we can calculate the ages of the various characteristic beds (including fossil zones, seismic reflection beds, and marker layers of electrical properties) for any given borehole-section when it was divided into facies, and check the validity of the chronology. According to all those studies, the stratigraphic and geochronologic analysis program of the Quaternary deposits in the Qaidam Basin has permitted a detailed discussion to be made in this paper.
基金Ministry of Science and Technology&Biotechnology(WBDSTBT)。
文摘Present research is an endeavour to scrutinise the spatio-temporal climatic characteristics of tropical cyclones(TCs)bustle in the Bay of Bengal basin,found in RSMC-IMD data all through 1971–2020.A large number of TCs,i.e.121 with a decadal average of 35.2 TCs has been examined for the last 50 years where depression(D)and deep depression(DD)have not been taken into account as these are less violent in nature.During the study periods,inter-annual and inter-decadal variation in cyclogenesis,landfall,length,speed,track shape and sinuosity,energy metrics and damage profile have been perceived.The study is clearly showing TCs took the northward track during the pre-monsoon season and made their landfall across the coasts of Bangladesh and Myanmar,while post-monsoon TCs made their landfall directly on the coasts of Orissa and West Bengal.In the post-monsoon phase,VF,ACE and PDI are significantly higher than in the monsoon season in the case of TCs and higher in the pre-monsoon season than in the monsoon season in the case of TCs comparing the energy metrics in different seasons.TC activity is comparatively pronounced during La Niña and El Niño regimes respectively and the genesis position in the BoB is moves to the east(west)of 87°E.During the cold regime,the number of extreme TC above the VSCS category,increased intensely.It is believed that the research findings will help stakeholders of the nation to take accurate strides to combat such violent events with persistent intensification.
文摘Global climate change,climate extremes,and overuse of natural resources are all major contributors to the risk brought on by cyclones.In I West Bengal state of India,the Pathar Pratima Block frequently experiences a variety of risks that result in significant loss of life and livelihood.In order to govern coastal society,it is crucial to measure and map the multi-hazards risk status.To depict the multi-hazards vulnerability and risk status,no cutting-edge models are currently being applied.Predicting distinct physical vulnerabilities is possible using a variety of cutting-edge machine learning techniques.This study set out to precisely describe multi-hazard risk using powerful machine learning methods.This study involved the use of Analytic Hierarchical Analysis and two cutting-edge machine-learning algorithms-Random Forest and Artificial Neural Network,which are yet underutilized in this area.The multi-hazards risk was determined by taking into account six criteria.The southern and eastern regions of the research area are clearly identified by the multi-hazards risk maps as having high to extremely high hazards risk levels.Cyclonic hazards and embankment breaching are the main dominant factors among the multi-hazards.The machine learning approach is the most accurate model for mapping the multi-hazards risk where the ROC result of Random forest and artificial neural network is more than the conventional method AHP.Here RF is the most validated model than the other two.The effectiveness,root mean square error,true skill statistics,Friedman and Wilcoxon rank test,and area under the curve of receiver operating characteristic tests were used to evaluate the prediction capacity of newly constructed models.The RMSE values of 0.24 and 0.26,TSS values of 0.82 and 0.73,and AUC values of 88.20%and 89.10%as produced by RF and ANN models,respectively,were all excellent.
基金This research is funded by NASA(National Aeronautics and Space Administration)NCCS and AIST(NNX15AM85G)NSF I/UCRC,CSSI,and EarthCube Programs(1338925 and 1835507).
文摘Earth observations and model simulations are generating big multidimensional array-based raster data.However,it is difficult to efficiently query these big raster data due to the inconsistency among the geospatial raster data model,distributed physical data storage model,and the data pipeline in distributed computing frameworks.To efficiently process big geospatial data,this paper proposes a three-layer hierarchical indexing strategy to optimize Apache Spark with Hadoop Distributed File System(HDFS)from the following aspects:(1)improve I/O efficiency by adopting the chunking data structure;(2)keep the workload balance and high data locality by building the global index(k-d tree);(3)enable Spark and HDFS to natively support geospatial raster data formats(e.g.,HDF4,NetCDF4,GeoTiff)by building the local index(hash table);(4)index the in-memory data to further improve geospatial data queries;(5)develop a data repartition strategy to tune the query parallelism while keeping high data locality.The above strategies are implemented by developing the customized RDDs,and evaluated by comparing the performance with that of Spark SQL and SciSpark.The proposed indexing strategy can be applied to other distributed frameworks or cloud-based computing systems to natively support big geospatial data query with high efficiency.
文摘Thirty-nine soils were studied on Holocene and late Pleistocene geomorphic surfaces.Granodiorite, sandstone, and alluvium derived from these rocks are the parent materials. Climateis Mediterranean. Chamise （Adenostoma faciculatum） is on the drier sites and redwood （Sequoiasempervirens） on the moister sites. Our objectives are twofold, （1） Find if today’s two-season wet-dry, subhumid climate explains the general noncalcic nature of the soils, or if not （2） accept thattheir noncalcic nature results from more moist past climates and define some indicator soilproperties. The depth to carbonate in the soils formed in calcareous materials on Holocenesurfaces corresponds roughly to the average annual depth of water movement, not to the predictedwettest years. We accept then, that the relict paleosols formed under one or more pluvial cyclesbecause they are free of carbonate below their B horizons. Defined levels of pedon clayaccumulation, dithionite-citrate extractable Fe （Fe<sub>d</sub>） accumulation in the B horizons, cationexchange capacity at pH 7 （CEC<sub>7</sub>） to clay ratios, and the minimum base saturation at pH 7 （BS<sub>7</sub>） inthe pedons are useful properties for separating these relict paleosols from the Holocene age soils.A further evidence of the relict nature of the soils on the Pleistocene surfaces is the weatheringreversal noted in these previously weathered materials.
