Despite the maturity of ensemble numerical weather prediction(NWP),the resulting forecasts are still,more often than not,under-dispersed.As such,forecast calibration tools have become popular.Among those tools,quantil...Despite the maturity of ensemble numerical weather prediction(NWP),the resulting forecasts are still,more often than not,under-dispersed.As such,forecast calibration tools have become popular.Among those tools,quantile regression(QR)is highly competitive in terms of both flexibility and predictive performance.Nevertheless,a long-standing problem of QR is quantile crossing,which greatly limits the interpretability of QR-calibrated forecasts.On this point,this study proposes a non-crossing quantile regression neural network(NCQRNN),for calibrating ensemble NWP forecasts into a set of reliable quantile forecasts without crossing.The overarching design principle of NCQRNN is to add on top of the conventional QRNN structure another hidden layer,which imposes a non-decreasing mapping between the combined output from nodes of the last hidden layer to the nodes of the output layer,through a triangular weight matrix with positive entries.The empirical part of the work considers a solar irradiance case study,in which four years of ensemble irradiance forecasts at seven locations,issued by the European Centre for Medium-Range Weather Forecasts,are calibrated via NCQRNN,as well as via an eclectic mix of benchmarking models,ranging from the naïve climatology to the state-of-the-art deep-learning and other non-crossing models.Formal and stringent forecast verification suggests that the forecasts post-processed via NCQRNN attain the maximum sharpness subject to calibration,amongst all competitors.Furthermore,the proposed conception to resolve quantile crossing is remarkably simple yet general,and thus has broad applicability as it can be integrated with many shallow-and deep-learning-based neural networks.展开更多
The Tibet Plateau is one of the regions with the richest solar energy resources in the world.In the process of achieving carbon neutrality in China,the development and utilization of solar energy resources in the regi...The Tibet Plateau is one of the regions with the richest solar energy resources in the world.In the process of achieving carbon neutrality in China,the development and utilization of solar energy resources in the region will play an important role.In this study,the gridded solar resource data with 1km resolution in Tibet were obtained by spatial correction and downscaling of SMARTS model.On this basis,the spatial and temporal distribution characteristics of solar energy resources in the region in the past 30 years(1991–2020)are finely evaluated,and the annual global horizontal radiation resource is calculated.The results show that:1)The average annual global horizontal radiation amount in Tibet is 1816 kWh/m^(2).More than 60%of the area belongs to the“Most abundant”(GHI≥1750 kWh/m^(2))area of China’s solar energy resources category A,and nearly 40%belongs to the“Quite abundant”(1400≤GHI<1750)area of China’s solar energy resource category B.2)In space,the solar energy resources in Tibet increased gradually from north to south and from east to west.Lhasa,Central and Eastern Shigatse,Shannan,and Southwestern Ali are the most abundant cities,with a maximum annual radiation level of 2189 kWh/m2.3)In terms of time,the total horizontal radiation in Tibet was the highest in May and the lowest in December.74%of the total area belongs to the“Very stable”(R_(w)≥0.47)area of solar resource stability category A,and 26%belongs to the“stable”(0.36≤R_(w)<0.47)area of solar resource stability category B.Solar energy resources in the region show the characteristics of both strong and stable.Average solar energy resources in the region have shown a fluctuating downward trend over the past 30 years,with an average decline of about 12.86(kWh/m2)per decade.4)In terms of solar radiation resources reaching the earth’s surface,the theoretical total amount of annual horizontal radiation in Tibet is about 240.07 billion tons of standard coal or 222.91 billion kilowatts on average.展开更多
Qinghai Lake Basin area in Gangcha county is selected as the study area in terms of desertification change features in this paper.Based on the remote sensing(RS)and global positioning system(GPS)technologies,the deser...Qinghai Lake Basin area in Gangcha county is selected as the study area in terms of desertification change features in this paper.Based on the remote sensing(RS)and global positioning system(GPS)technologies,the desertification information range from 1989 to 2014 in the study area is extracted.Using the method of the decision tree,the desertification in the research area is been divided into four grades including mild desertification,moderate desertification,severe desertification and serious desertification.The change characteristics of desertification in the study area were analyzed in detail,which showed that the desertification in the study area experienced a process of first development and then a reversal.The rapid development of desertification appears in the 1990s,where about 1101.22 kilometers of desertification area was increased in this stage.Since the twenty-first Century,the desertification is gradually significant recovered and local area exist intensified desertification.There are tendencies of interactive transform in different types of desertification.The tendencies of different degrees of desertification land are rising,and there’re some differences in rising rates,where the expansion rate of moderate desertification is the biggest,increasing by 7.27 kilometers per year.展开更多
Land desertification is a widely concerned ecological environment problem.Studying the evolution trend of desertification types is of great significance to prevent and control land desertification.In this study,we app...Land desertification is a widely concerned ecological environment problem.Studying the evolution trend of desertification types is of great significance to prevent and control land desertification.In this study,we applied the decision tree classification method,to study the land area and temporal and spatial change law of different types of desertification in the North Bank of Qinghai Lake area from 1987 to 2014,based on the current land use situation and TM remote sensing image data of Haiyan County,Qinghai Province,The results show that the area of mild desertification land and moderate desertification land in the study area has decreased,while the area of severe desertification land and extreme desertification land has increased significantly in the past 30 years.The area of desertification land decreased by 4.02 km2,of which the area of mild and moderate desertification land decreased by 39.73 km2 and 36.8 km2 respectively,and the area of severe and extreme desertification land increased by 32.78 km2 and 39.73 km2 respectively.As for the mutual transformation relationship,the transformation from severe desertification land to extreme desertification land is the main,and the junction of severe desertification land and extreme desertification land is the sensitive area of transformation.In the north shore of Qinghai Lake,the sandy land tends to expand eastward.The research provides reference basis for local land desertification monitoring,and has a great guidance for local effective land desertification and soil and water conservation.展开更多
In this paper,RS,GIS and GPS technologies are used to interpret the remote sensing images of the north shore of Qinghai Lake from 1987 to 2014 according to the inversion results of vegetation coverage(FVC),albedo,land...In this paper,RS,GIS and GPS technologies are used to interpret the remote sensing images of the north shore of Qinghai Lake from 1987 to 2014 according to the inversion results of vegetation coverage(FVC),albedo,land surface temperature(LST),soil moisture(WET)and other major parameters after image preprocessing,such as radiometric correction,geometric correction and atmospheric correction.On this basis,the decision tree classification method based on landsat8 remote sensing image is used to classify the desertification land in this area,and the development and change of desertification in this period are analyzed.The results show that the fluctuation of desertification land area in this area increased during the study period,but from 2003 to 2014,the land area of mild desertification,moderate desertification and severe desertification landwere respectively decreased 0.92,145.89 and 29.39 km2,while the area of serious desertification land still has a slow increasing trend.Whether the driving force of desertification change trend in this area is caused by human factors or global change needs to be further studied.展开更多
The fundamental scientific and engineering knowledge concerning the solar power curve,which maps solar irradiance and other auxiliary meteorological variables to photovoltaic output power,has been gathered and put for...The fundamental scientific and engineering knowledge concerning the solar power curve,which maps solar irradiance and other auxiliary meteorological variables to photovoltaic output power,has been gathered and put forward in the preceding tutorial review.Despite the many pages of that review,it was incomplete in the sense that it did not elaborate on the applications of this very important tool of solar energy meteorology.Indeed,solar power curves are ubiquitously needed in a broad spectrum of solar forecasting and solar resource assessment tasks.Hence,this tutorial review should continue from where it left off and present examples concerning the usage of solar power curves.In a nutshell,this tutorial review,together with the preceding one,should elucidate how surface shortwave radiation data,be they ground-based,satelliteretrieved,or model-output,are bridged to various power system operations via solar power curves.展开更多
Satellite remote sensing is essential for solar energy meteorology.The 14-channel Advanced Geostationary Radiation Imager of the Fengyun-4 series of satellites performs a full-disc scan over greater China every 15 min...Satellite remote sensing is essential for solar energy meteorology.The 14-channel Advanced Geostationary Radiation Imager of the Fengyun-4 series of satellites performs a full-disc scan over greater China every 15 min,providing highgranularity information that allows the retrieval of cloud properties,aerosol optical depth,and precipitable water vapor content,which can facilitate the acquisition of surface solar irradiance components through physical methods.Machinelearning methods have also shown potential in providing accurate end-to-end surface solar radiation retrievals.Albeit the physical principles of irradiance retrieval and machine-learning algorithms are fairly well known,the public service concerning disseminating the irradiance product to the energy and power industry still lacks robustness and consistency.In this perspective article,the status quo of Fengyun-4 irradiance products is first reviewed.Then,from the perspective of solar resource assessment and forecasting,three fundamental characteristics of the kind of irradiance products that are most serviceable to the solar energy sector are identified,namely,coverage,timeliness,and accessibility.Finally,an outlook on the new-generation Fengyun radiation service is put forward,and the prospective scientific and practical challenges are elaborated.展开更多
基金supported by the National Natural Science Foundation of China (Project No.42375192)the China Meteorological Administration Climate Change Special Program (CMA-CCSP+1 种基金Project No.QBZ202315)support by the Vector Stiftung through the Young Investigator Group"Artificial Intelligence for Probabilistic Weather Forecasting."
文摘Despite the maturity of ensemble numerical weather prediction(NWP),the resulting forecasts are still,more often than not,under-dispersed.As such,forecast calibration tools have become popular.Among those tools,quantile regression(QR)is highly competitive in terms of both flexibility and predictive performance.Nevertheless,a long-standing problem of QR is quantile crossing,which greatly limits the interpretability of QR-calibrated forecasts.On this point,this study proposes a non-crossing quantile regression neural network(NCQRNN),for calibrating ensemble NWP forecasts into a set of reliable quantile forecasts without crossing.The overarching design principle of NCQRNN is to add on top of the conventional QRNN structure another hidden layer,which imposes a non-decreasing mapping between the combined output from nodes of the last hidden layer to the nodes of the output layer,through a triangular weight matrix with positive entries.The empirical part of the work considers a solar irradiance case study,in which four years of ensemble irradiance forecasts at seven locations,issued by the European Centre for Medium-Range Weather Forecasts,are calibrated via NCQRNN,as well as via an eclectic mix of benchmarking models,ranging from the naïve climatology to the state-of-the-art deep-learning and other non-crossing models.Formal and stringent forecast verification suggests that the forecasts post-processed via NCQRNN attain the maximum sharpness subject to calibration,amongst all competitors.Furthermore,the proposed conception to resolve quantile crossing is remarkably simple yet general,and thus has broad applicability as it can be integrated with many shallow-and deep-learning-based neural networks.
基金This work was supported by the Major Science and Technology Project of the Science and Technology Department of Tibet under Grant Number XZ202101ZD0015Gthe Second Tibet Plateau Scientific Expedition and Research Program(STEP)under Grant Number 2019QZKK0804.
文摘The Tibet Plateau is one of the regions with the richest solar energy resources in the world.In the process of achieving carbon neutrality in China,the development and utilization of solar energy resources in the region will play an important role.In this study,the gridded solar resource data with 1km resolution in Tibet were obtained by spatial correction and downscaling of SMARTS model.On this basis,the spatial and temporal distribution characteristics of solar energy resources in the region in the past 30 years(1991–2020)are finely evaluated,and the annual global horizontal radiation resource is calculated.The results show that:1)The average annual global horizontal radiation amount in Tibet is 1816 kWh/m^(2).More than 60%of the area belongs to the“Most abundant”(GHI≥1750 kWh/m^(2))area of China’s solar energy resources category A,and nearly 40%belongs to the“Quite abundant”(1400≤GHI<1750)area of China’s solar energy resource category B.2)In space,the solar energy resources in Tibet increased gradually from north to south and from east to west.Lhasa,Central and Eastern Shigatse,Shannan,and Southwestern Ali are the most abundant cities,with a maximum annual radiation level of 2189 kWh/m2.3)In terms of time,the total horizontal radiation in Tibet was the highest in May and the lowest in December.74%of the total area belongs to the“Very stable”(R_(w)≥0.47)area of solar resource stability category A,and 26%belongs to the“stable”(0.36≤R_(w)<0.47)area of solar resource stability category B.Solar energy resources in the region show the characteristics of both strong and stable.Average solar energy resources in the region have shown a fluctuating downward trend over the past 30 years,with an average decline of about 12.86(kWh/m2)per decade.4)In terms of solar radiation resources reaching the earth’s surface,the theoretical total amount of annual horizontal radiation in Tibet is about 240.07 billion tons of standard coal or 222.91 billion kilowatts on average.
基金This work was supported by the National Natural Science Foundation of China“Study on the dynamic mechanism of grassland ecosystem response to climate change in Qinghai Plateau”under grant number U20A2098.
文摘Qinghai Lake Basin area in Gangcha county is selected as the study area in terms of desertification change features in this paper.Based on the remote sensing(RS)and global positioning system(GPS)technologies,the desertification information range from 1989 to 2014 in the study area is extracted.Using the method of the decision tree,the desertification in the research area is been divided into four grades including mild desertification,moderate desertification,severe desertification and serious desertification.The change characteristics of desertification in the study area were analyzed in detail,which showed that the desertification in the study area experienced a process of first development and then a reversal.The rapid development of desertification appears in the 1990s,where about 1101.22 kilometers of desertification area was increased in this stage.Since the twenty-first Century,the desertification is gradually significant recovered and local area exist intensified desertification.There are tendencies of interactive transform in different types of desertification.The tendencies of different degrees of desertification land are rising,and there’re some differences in rising rates,where the expansion rate of moderate desertification is the biggest,increasing by 7.27 kilometers per year.
基金This research was supported by the National Nature&Science Foundation of China“Study on the dynamic mechanism of grassland ecosystem response to climate change in Qinghai Plateau”(No.U20A2098)the second Tibetan plateau scientific expedition and research program(STEP,No.2019QZKK0804)China Huaneng Group Co.Science and Technology Program“The research development and implement on the evaluation technology of wind resource”(No.HNKJ18-H31).
文摘Land desertification is a widely concerned ecological environment problem.Studying the evolution trend of desertification types is of great significance to prevent and control land desertification.In this study,we applied the decision tree classification method,to study the land area and temporal and spatial change law of different types of desertification in the North Bank of Qinghai Lake area from 1987 to 2014,based on the current land use situation and TM remote sensing image data of Haiyan County,Qinghai Province,The results show that the area of mild desertification land and moderate desertification land in the study area has decreased,while the area of severe desertification land and extreme desertification land has increased significantly in the past 30 years.The area of desertification land decreased by 4.02 km2,of which the area of mild and moderate desertification land decreased by 39.73 km2 and 36.8 km2 respectively,and the area of severe and extreme desertification land increased by 32.78 km2 and 39.73 km2 respectively.As for the mutual transformation relationship,the transformation from severe desertification land to extreme desertification land is the main,and the junction of severe desertification land and extreme desertification land is the sensitive area of transformation.In the north shore of Qinghai Lake,the sandy land tends to expand eastward.The research provides reference basis for local land desertification monitoring,and has a great guidance for local effective land desertification and soil and water conservation.
基金supported by the National Natural Science Foundation of China“Study on the dynamic mechanism of grassland ecosystem response to climate change in Qinghai Plateau”under grant number U20A2098the Second Tibet Plateau Scientific Expedition and Research Program(STEP)under grant number 2019QZKK0804.
文摘In this paper,RS,GIS and GPS technologies are used to interpret the remote sensing images of the north shore of Qinghai Lake from 1987 to 2014 according to the inversion results of vegetation coverage(FVC),albedo,land surface temperature(LST),soil moisture(WET)and other major parameters after image preprocessing,such as radiometric correction,geometric correction and atmospheric correction.On this basis,the decision tree classification method based on landsat8 remote sensing image is used to classify the desertification land in this area,and the development and change of desertification in this period are analyzed.The results show that the fluctuation of desertification land area in this area increased during the study period,but from 2003 to 2014,the land area of mild desertification,moderate desertification and severe desertification landwere respectively decreased 0.92,145.89 and 29.39 km2,while the area of serious desertification land still has a slow increasing trend.Whether the driving force of desertification change trend in this area is caused by human factors or global change needs to be further studied.
基金supported by the National Natural Science Foundation of China(project no.42375192)supported by the National Natural Science Foundation of China(project no.42030608)+3 种基金China Meteorological Administration Climate Change Special Program(CMA-CCSPproject no.QBZ202315)supported by the National Research,Development and Innovation Fund,project no.OTKA-FK 142702the János Bolyai Research Scholarship。
文摘The fundamental scientific and engineering knowledge concerning the solar power curve,which maps solar irradiance and other auxiliary meteorological variables to photovoltaic output power,has been gathered and put forward in the preceding tutorial review.Despite the many pages of that review,it was incomplete in the sense that it did not elaborate on the applications of this very important tool of solar energy meteorology.Indeed,solar power curves are ubiquitously needed in a broad spectrum of solar forecasting and solar resource assessment tasks.Hence,this tutorial review should continue from where it left off and present examples concerning the usage of solar power curves.In a nutshell,this tutorial review,together with the preceding one,should elucidate how surface shortwave radiation data,be they ground-based,satelliteretrieved,or model-output,are bridged to various power system operations via solar power curves.
基金supported by the National Natural Science Foundation of China(project no.42375192)。
文摘Satellite remote sensing is essential for solar energy meteorology.The 14-channel Advanced Geostationary Radiation Imager of the Fengyun-4 series of satellites performs a full-disc scan over greater China every 15 min,providing highgranularity information that allows the retrieval of cloud properties,aerosol optical depth,and precipitable water vapor content,which can facilitate the acquisition of surface solar irradiance components through physical methods.Machinelearning methods have also shown potential in providing accurate end-to-end surface solar radiation retrievals.Albeit the physical principles of irradiance retrieval and machine-learning algorithms are fairly well known,the public service concerning disseminating the irradiance product to the energy and power industry still lacks robustness and consistency.In this perspective article,the status quo of Fengyun-4 irradiance products is first reviewed.Then,from the perspective of solar resource assessment and forecasting,three fundamental characteristics of the kind of irradiance products that are most serviceable to the solar energy sector are identified,namely,coverage,timeliness,and accessibility.Finally,an outlook on the new-generation Fengyun radiation service is put forward,and the prospective scientific and practical challenges are elaborated.
