基于精密太阳光谱辐射计的气象辐射观测
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摘要
目前,气象业务观测普遍采用的积分型太阳辐射观测仪器存在观测数据信息量少、数据差异大的观测瓶颈,已无法满足目前众多应用科学研究领域对太阳光谱辐射精细化观测的需求,具有高光谱分辨率的精密光谱辐射计的仪器研制及观测方法与技术已成为太阳辐射观测的前沿科技问题。在此背景下,为解决气象领域太阳辐射的精细化观测问题,开展了深入的科学研究与技术开发工作。重点阐述了仪器开发成果和数据观测分析方法,首先介绍了开发研制的用于地基太阳光谱辐照度观测的光谱辐射计系统。光谱辐射计的分光系统采用了平场凹面光栅结构,具有低杂散光、高收光效率和高可靠性的特点,尤其适用于长期无人值守的户外观测。系统所采用的平场凹面光栅的像差校正特性对于300～1 100 nm这种宽谱段的应用来讲更为合适,在整个谱段范围内光谱分辨率变化很小,不同波长通道的带宽基本一致,使用25μm狭缝时光谱分辨率(FWHM)约为2 nm,像素采样间隔小于0. 5 nm。对于太阳辐射观测来讲,这是一种谱段范围和分辨率都与需求十分匹配的专用光谱辐照度观测仪器。其次,在观测数据的基础上,阐述和分析了气象等领域的光谱应用观测方法。太阳辐射照度分布的能量通过不同参数化模型约束的接收系统收集,将太阳光谱辐射在半球天穹中的变化及分布进行约束并划分为水平总辐照度(GHI),法向直接辐照度(DNI)和水平散射辐照度(DHI)三种光谱辐照度辐射分量,阐述了基于GHI,DNI和DHI三种观测形式下的数据特征与用途。其中,GHI是地表实际辐照度水平,适用于太阳能资源评估; DHI反映大气和云态; DNI作为直接透射形式,可用于计算日照时数和分析大气参量。并且,进一步分析了观测形式、光谱特征与地理(经度、纬度、海拔高度、大气质量)及气象参数(云量、大气吸收)之间的互易演算关系。与传统的波长积分式辐射观测相比,太阳光谱辐射计为辐射能量观测增加了波长信息维度。从DNI形式的光谱辐照度数据中可以看出,不同波长之间的辐射能量变化显著,而这些变化与大气变化密切相关。因此,太阳光谱辐照度数据不仅仅是为业务观测提供更精细化的太阳辐射信息,更提供了丰富的辐射能量的变化信息通道,利用特征波长维度的辐射信息,可进一步通过模型反演计算气溶胶光学厚度、臭氧、水汽等大气参数。通过精密太阳光谱辐射计,可将纳米分辨率水平的太阳光谱辐照度作为基础业务运行数据,提供精细化的太阳辐射分布及变化信息用于气象与气候模型、光伏资源评估与生态环境等研究;同时也为辐射波长分布中所蕴含的气候、农业、生态等领域关心的各种通量监测和演化关系研究提供了有力的数据信息及观测工具。
The wavelength-integral type solar radiation observation instrument currently used in meteorological service observation has met the bottleneck with insufficient detail of solar radiation and large differences of data,so it has been unable to meet the needs of applied scientific research on the fine observation of solar spectral radiation. Observation methods as well as instrumentation research and development of the precision spectroradiometer with high spectral resolution have become the frontier science and technology issues in solar radiation observation of meteorological field. Under aforementioned scientific research background,our research group has been supported by National( Meteorological) Industry Research Special Funds for Public Welfare Projects. In order to solve the problem of fine observation of solar radiation in the meteorological application field,in-depth scientific research and technology development have been carried out. This paper focuses on the discussion about the instrument development achievements and analysis methods of observation data. Firstly,the spectroradiometer system used for ground-based solar spectral irradiance observation is introduced. The optical bench of the spectroradiometer adopts a spectrograph structure based on flat field concave grating,which has the excellent optical characteristics such as low stray light,high light collection efficiency and high reliability,so it is especially suitable for long-term unattended outdoor meteorological observation. The aberration correction characteristic of flat field concave grating used in the spectroradiometer system is more suitable for the wide spectrum range application from 300 to 1 100 nm,and there is almost no change of spectral resolution covering the entire measured spectrum range,that means the bandwidth of different wavelength channels is basically the same. The spectral resolution( FWHM,Full Width at Half Maximum) is approximately 2 nm when 25 μm slit is used,and the sampling wavelength interval is less than 0. 5 nm. So,this spectroradiometer is an advanced spectral irradiance measuring instrument for solar radiation observation,and its spectrum range and spectral resolution match the solar observation demand very well. Secondly,on the basis of the observation data,the observation methods of solar spectral irradiance in meteorology application are expounded and analyzed. The spatial-distribution energy of the solar irradiance is collected by a receiving unit with different device parametric models. The movement process and distribution forms of solar spectral radiation in the hemisphere sky are dimensional constrained and made into three different spectral irradiance components. The three spectral irradiance components are Global Horizontal Irradiance( GHI),Direct Normal Irradiance( DNI) and Diffuse Horizontal Irradiance( DHI). Based on data of GHI,DNI and DHI,the data features and application purpose of three observation forms are expounded. GHI is the actual irradiance intensity level on the earth surface,which is suitable for solar resource assessment.DHI reflects the motion of atmosphere and cloud phase state. DNI as a direct transmission energy form can be used to calculate sunshine duration and analyze atmospheric parameters. Furthermore,the calculus function relationships among observation forms,spectral signature and geographical parameters( longitude,latitude,altitude and air mass) and meteorological parameters( cloud amount and atmospheric absorption) are further analyzed. Compared with the traditional wavelength-integral type radiation observation,the solar spectroradiometer increases the dimensions of the wavelength information channels for the radiation energy observation. From the spectral irradiance data of the direct normal irradiance form,it can be seen that the radiation energy varies significantly at different wavelengths,which are closely related to the movement process of the atmosphere. Therefore,solar spectral irradiance data not only provide more detailed information for service observation,but also provide more various information channels of radiation energy. Using the radiation quantity information of the feature wavelength channels,the atmospheric parameters such as Aerosol Optical Depth( AOD),Total Ozone Column(TOC) and Water Vapor Column(WVC) can be calculated by the inversion models. The precision solar spectroradiometer provides the solar spectral irradiance with high resolution grade in the order of nanometer as the basic service data,and the detailed information on the distribution and vary of solar radiation can be used for research on meteorological models and climatic models,the assessment of photovoltaic resources and the ecological environment,etc. And it also provides impactful scientific research data and helpful observation tools,and abundant interested information can be extracted in radiation energy distribution on wavelength for variety of ecosystem flux monitoring and evolution relationship research,especially in the areas of climate,agriculture and ecology.
The wavelength-integral type solar radiation observation instrument currently used in meteorological service observation has met the bottleneck with insufficient detail of solar radiation and large differences of data,so it has been unable to meet the needs of applied scientific research on the fine observation of solar spectral radiation. Observation methods as well as instrumentation research and development of the precision spectroradiometer with high spectral resolution have become the frontier science and technology issues in solar radiation observation of meteorological field. Under aforementioned scientific research background,our research group has been supported by National( Meteorological) Industry Research Special Funds for Public Welfare Projects. In order to solve the problem of fine observation of solar radiation in the meteorological application field,in-depth scientific research and technology development have been carried out. This paper focuses on the discussion about the instrument development achievements and analysis methods of observation data. Firstly,the spectroradiometer system used for ground-based solar spectral irradiance observation is introduced. The optical bench of the spectroradiometer adopts a spectrograph structure based on flat field concave grating,which has the excellent optical characteristics such as low stray light,high light collection efficiency and high reliability,so it is especially suitable for long-term unattended outdoor meteorological observation. The aberration correction characteristic of flat field concave grating used in the spectroradiometer system is more suitable for the wide spectrum range application from 300 to 1 100 nm,and there is almost no change of spectral resolution covering the entire measured spectrum range,that means the bandwidth of different wavelength channels is basically the same. The spectral resolution( FWHM,Full Width at Half Maximum) is approximately 2 nm when 25 μm slit is used,and the sampling wavelength interval is less than 0. 5 nm. So,this spectroradiometer is an advanced spectral irradiance measuring instrument for solar radiation observation,and its spectrum range and spectral resolution match the solar observation demand very well. Secondly,on the basis of the observation data,the observation methods of solar spectral irradiance in meteorology application are expounded and analyzed. The spatial-distribution energy of the solar irradiance is collected by a receiving unit with different device parametric models. The movement process and distribution forms of solar spectral radiation in the hemisphere sky are dimensional constrained and made into three different spectral irradiance components. The three spectral irradiance components are Global Horizontal Irradiance( GHI),Direct Normal Irradiance( DNI) and Diffuse Horizontal Irradiance( DHI). Based on data of GHI,DNI and DHI,the data features and application purpose of three observation forms are expounded. GHI is the actual irradiance intensity level on the earth surface,which is suitable for solar resource assessment.DHI reflects the motion of atmosphere and cloud phase state. DNI as a direct transmission energy form can be used to calculate sunshine duration and analyze atmospheric parameters. Furthermore,the calculus function relationships among observation forms,spectral signature and geographical parameters( longitude,latitude,altitude and air mass) and meteorological parameters( cloud amount and atmospheric absorption) are further analyzed. Compared with the traditional wavelength-integral type radiation observation,the solar spectroradiometer increases the dimensions of the wavelength information channels for the radiation energy observation. From the spectral irradiance data of the direct normal irradiance form,it can be seen that the radiation energy varies significantly at different wavelengths,which are closely related to the movement process of the atmosphere. Therefore,solar spectral irradiance data not only provide more detailed information for service observation,but also provide more various information channels of radiation energy. Using the radiation quantity information of the feature wavelength channels,the atmospheric parameters such as Aerosol Optical Depth( AOD),Total Ozone Column(TOC) and Water Vapor Column(WVC) can be calculated by the inversion models. The precision solar spectroradiometer provides the solar spectral irradiance with high resolution grade in the order of nanometer as the basic service data,and the detailed information on the distribution and vary of solar radiation can be used for research on meteorological models and climatic models,the assessment of photovoltaic resources and the ecological environment,etc. And it also provides impactful scientific research data and helpful observation tools,and abundant interested information can be extracted in radiation energy distribution on wavelength for variety of ecosystem flux monitoring and evolution relationship research,especially in the areas of climate,agriculture and ecology.
引文
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[2] Gr9bner J,Kroger I,Egli L,et al. Atmospheric Measurement Techniques,2017,10(9):3375.
[3] Raptis P I,Kazadzis S,Gr9bner J,et al. Atmospheric Measurement Techniques,2018,11(2):1143.
[4] World Meteorological Organization,2010:Instruments to Measure Solar Ultraviolet Radiation Part 4:Array Spectroradiometers,WMO/TD-No.1538,2010.
[5] World Meteorological Organization,2014:Standard Operating Procedures(SOPs)for Spectral Instruments Measuring Spectral Solar Ultraviolet Irradiance,WMO/GAW-No. 212,2014.
[6] Liu Liying,Zheng Feng,Zhang Guoyu,et al. Instrumentation,2017,4(01):24.
[7] Zheng F,Liu L,Zhang G,et al. Proceedings of SPIE-The Photoelectronic Technology Committee Conferences,2015,9795:97951C-1-4.
[8] International Organization for Standardization,1992:Solar Energy-Reference Solar Spectral Irradiance at the Ground at Different Receiving Conditions—Part 1:Direct Normal and Hemispherical Solar Irradiance for Air Mass 1. 5,ISO 9845-1; 1992,Geneva.
[9] Paulescu M,Paulescu E,Gravila P,et al. Weather Modeling and Forecasting of PV Systems Operation. London:Springer,2013.
[10] Vignola F,Derocher Z,Peterson J,et al. Solar Energy,2016,129:224.
[11] Nou J,Chauvin R,Thil S,et al. Applied Mathematical Modelling,2016,40(15-16):7245.