宝坻太阳辐射资料可用性研究

应用典型的辐射资料质量检验方法、辐射数据变化特征分析、人工与器测日照对比分析及太阳总辐射与相关辐射要素间的统计分析对天津市宝坻国家级基本气象站站内的太阳辐射观测系统试运行期间的辐射观测数据进行了质量分析,结果表明,试运行期间数据到报情况理想,总、散射辐射观测数据的BSRN的质量检验合格率为100%,直接辐射合格率为85%,净辐射通过了仪器阀值质量检验;太阳辐射值及变化特征符合理论实际;人工与器测日照时数具有很好的线性相关性(R2=0.96),总辐射与日照时数及散射辐射之间的线性变化与历史经验结论吻合。总体来看,宝坻太阳辐射系统观测数据可用性较高,能够满足日常业务需求。     

东莞市辐射强度特征及影响因子

东莞观测站采用地面辐射基准站网(BSRN)通用的荷兰Kipp & Zonen设备,进行太阳短波辐射和地面、大气长波辐射观测。利用2010年8月—2011年7月的观测数据,用统计分析的方法,得到地面太阳短波辐射和地面、大气长波辐射强度的变化特征,并初步分析了影响辐射强度变化的因子。结果表明,东莞市各月的太阳总辐射平均值呈现单峰值变化,且夏季＞秋季＞春季＞冬季,短波辐射各分量的日变化也呈明显单峰型变化特征;长波辐射的日、月变化趋势较平缓;东莞市全年各月净辐射通量平均值均为正值。云是影响太阳辐射强度变化的显著因子,对直接辐射的衰减更明显,多云天气的总辐射、直接辐射全年平均衰减率分别为11%、34%,阴天总辐射、直接辐射全年平均衰减率分别达到47%、83%。大气透明度对短波辐射和长波辐射强度变化均产生影响,无霾日总辐射、直接辐射、反射辐射强度均比灰霾日强,而散射辐射则较弱,灰霾日的天空长波辐射及地面长波辐射强度稍强于无霾日。还探讨了总辐射观测值与理论值的差异,推测水汽对短波辐射的衰减是造成太阳短波辐射平衡存在差异的原因之一。      

CLM4.5在西北农牧交错带盐池站的模拟性能评估

农牧交错带具有草地、裸地、农田大面积相互镶嵌的独特下垫面,其地表水热过程变化复杂,亟需深入研究。利用宁夏盐池站2017年实际观测资料,对陆面过程模式CLM4.5的模拟性能进行检验。结果表明,在复杂下垫面下,CLM4.5仍能较好地模拟出草地的地面反射辐射、地面长波辐射和净辐射以及0~10 cm土壤含水量和温度的变化特征,但模拟值与观测值还存在一定偏差。CLM4.5能模拟出辐射通量的日变化特征,除5月外,地面反射辐射模拟值与观测值之间的偏差较小。地面长波辐射模拟值白天偏高,净辐射观测值与模拟值的相关系数为0.99,均方根误差为22.50 W·m^-2。土壤含水量观测值与模拟值的相关系数达0.83,但模拟值偏低,且模式对降雨后土壤含水量变化过程的模拟性能有待提高。土壤温度模拟值的日变化特征较为明显,观测值与模拟值的相关系数为0.98,均方根误差为2.82℃。     

不同天气条件下地基微波辐射计探测性能比对

利用探空数据和毫米波云雷达数据,对在大气探测试验基地同址观测的国内外3种型号地基微波辐射计进行1年（2016年10月—2017年9月）的比对分析,重点分析不同型号地基微波辐射计在晴空和云天下温、湿观测性能特征。结果表明:3种型号地基微波辐射计温度与探空相关系数均超过0.98,达到0.01显著性水平;晴空条件下,德国及国产地基微波辐射计温度平均误差均在±1℃以内（前者为负偏差,后者为正偏差）,误差较小,美国地基微波辐射计系统偏差约为-1.8℃;3种型号地基微波辐射计均方根误差随高度递增,整体均方根误差以德国地基微波辐射计2.2℃为最小,美国地基微波辐射计3.8℃为最大;在有云条件下,3种型号地基微波辐射计平均误差分布较晴空条件下无明显变化,均方根误差较晴空条件有约增加0.5℃。3种型号地基微波辐射计均呈晴空相对湿度误差小于云天误差,低空误差小于中高空误差的特点;晴空条件下,美国与国产地基微波辐射计相对湿度均方根误差分别为15%和18%左右,小于德国地基微波辐射计;云天条件下3种型号微波辐射计均方根误差均较大（26%左右）。     

临安与龙凤山辐射数据质量及初步结果比较

采用国际通用的辐射数据质量评估方法对2005—2011年浙江临安、黑龙江龙凤山两个区域大气本底站辐射观测资料进行质量评估与比较分析。结果表明:两站辐射数据通过物理可能限制检验与极端罕见限制检验的百分比均超过99.5%,但通过相关要素比较限制检验的百分比上,临安与龙凤山站分别降至97.9%与95.9%;双轴定位追踪太阳出现偏差是造成直接辐射与散射辐射数据精度降低的主要原因。CM21表的热偏移在-5 W·m-2以内,而其进行热偏移订正可以显著提高数据的通过率。对应同一太阳天顶角,临安站晴空总辐射与直接辐射均低于龙凤山站,散射辐射则相反,其原因是临安的大气透明系数较低,大气浑浊度较高。2006—2011年,临安站的大气向下长波辐射呈下降趋势,达到了0.01的显著性水平,且其多年平均值 (363.7±59.3 W·m-2) 显著高于龙凤山站 (274.9±77.6 W·m-2);龙凤山站晴空太阳总辐射呈增加趋势,达到了0.1的显著性水平。     

青藏高原纳木错站地表反照率观测与MODIS资料的对比分析

利用中国科学院纳木错多圈层相互作用综合观测研究站内太阳光度计观测的大气气溶胶光学厚度和整层气柱水汽总量,作为大气辐射传输模式的输入参数,模拟计算了2007年5月—2008年8月无雪期晴空条件下,正午时段该站的太阳总辐射和散射辐射,得到两者的比例S。基于MODIS发布的MCD43B3产品中的短波段黑空和白空反照率以及比例S,计算得到实际大气条件下地表反照率的卫星反演值,进而与地面观测值进行对比分析。结果显示,两者没有显著差别,可以满足气候模式对地表反照率绝对偏差为0.02的精度要求,且均方根偏差约为0.0156,最大偏差为0.046。雨季纳木错站的土壤含水量增加,使得该站晴空时观测的5 min平均地表反照率呈线性下降。     

我国地面辐射基准站观测数据完整性和合理性检查评价

利用BSRN推荐方法,对2007年6月 2010年12月内蒙古锡林浩特地面基准辐射站的辐射数据质量进行了检查,并对异常情况进行了分析.结果表明,锡林浩特基准辐射观测数据完整性较好,分钟数据缺测率最大为0.012％,满足缺测率低于2％的业务要求.质检结果表明,锡林浩特基准辐射观测数据总体质量良好,但数据异常季节性特征显著,总辐射在冬季超出极端罕见上限值的情况较多,直接辐射易在夏季超出极端罕见上限值;除去太阳跟踪器故障期间的数据,散射辐射超出极端罕见上限的情况也有出现;反射辐射则在冬季会偶尔超出极端罕见上限.总辐射、直接辐射和散射辐射易在夏季出现超出物理可能和极端罕见下限的情况,说明这些仪器在夏季较易出现零点的漂移.     

香河地区光合有效辐射观测分析研究

利用中国科学院大气物理研究所香河大气综合观测实验站(39°47′N,116°57′E)2004年10月至2005年12月共15个月的太阳辐射观测资料,分析了该地区光合有效辐射与太阳总辐射比值的(PAR/Rs)日变化和季节变化特征,得出月平均PAR/Rs值变化范围在1.808~2.048μE.J-1之间,最大值出现在夏季,最小值出现在冬季,年平均值为1.948μE.J-1。提出了一个利用太阳总辐射观测值计算光合有效辐射瞬时值的参数化算式,用该算式计算得到的PAR与实际观测值的均方根误差为19.28μE.m-2.s-1,有96%的计算值与观测值偏差在±10%以内。比较了香河地区与太湖地区、额济纳地区光合有效辐射瞬时最大值、小时累积最大值及日累积最大值的差异。     

利用MODTRAN 3计算我国太阳直接辐射和散射辐射

根据光的多次散射理论——离散纵标法,利用我国国家一级辐射测站的大气廓线,计算出晴空大气观测波段不同高度上的太阳直接辐射和向下散射辐射。将模式输出的地面辐射值与地面辐射观测资料进行比较,对不同高度的太阳直接辐射和向下散射辐射以及日变化进行了讨论。最终目的是直接由MODTRAN3计算我国辐射空白站的地面辐射值,以弥补我国辐射站稀少,时空分布短缺的不足。     

北京城市紫外辐射变化特征及经验估算方程

利用2004年4月—2005年6月在中国科学院大气物理研究所铁塔分部的紫外辐射观测数据,分析了北京城市紫外辐射的变化特征,结果表明,紫外辐射的变化规律与太阳总辐射一致,紫外辐射与总辐射的比值变化范围在0.02~0.04之间,晴天恒定在0.03,阴天在0.04左右,在沙尘暴过程中比值最小,为0.02。通过分析紫外辐射与大气质量数和平均晴空指数之间的关系,建立了适合于北京的全天候紫外辐射的估算方程。利用建立的估算方程及观测的总辐射值进行了紫外辐射的估算,紫外辐射的计算相对误差在10%以内。     

Modification of the SUNFLUX Solar Radiation Scheme with a New Aerosol Parameterization and Its Validation Using Observation Network Data

SUNFLUX is a fast parameterization scheme for determination of the solar radiation at the Earth's surface.In this paper,SUNFLUX is further modified in the treatment of aerosols.A new aerosol parameterization scheme is developed for five aerosol species.Observational data from Baseline Surface Radiation Network(BSRN),Surface Radiation Budget Network(SURFRAD) and Aerosol Robotic Network(AERONET) stations are used to evaluate the accuracy of the original and modified SUNFLUX schemes.General meteorological data are available at SURFRAD stations,but not at BSRN stations.Therefore,the total precipitable water content and aerosol data are obtained from AERONET stations.Fourteen stations are selected from both BSRN and AERONET.Cloud fraction data from MODIS are further used to screen the cloud.Ten-year average aerosol mixing ratios simulated by the CAM-chem system are used to calculate the fractions of aerosol optical depth for each aerosol species,and these fractions are further used to convert the observed total aerosol optical depth into the components of individual species for use in the evaluations.The proper treatment of multiple aerosol types in the model is discussed.The evaluation results using SUNFLUX with the new aerosol scheme,in terms of the BSRN dataset,are better than those using the original aerosol scheme under clear-sky conditions.However,the results using the SURFRAD dataset are slightly worse,attributable to the differences in the input water vapor and aerosol optical depth.Sensitivity tests are conducted to investigate the error response of the SUNFLUX scheme to the errors in the input variables.     

Parameterization and mapping of solar radiation in data sparse regions

Knowledge of temporal and spatial variation of solar radiation is essential for many applications. In this work, a simple and feasible procedure is conducted to map the daily solar radiation for Liaoning province, one of the most important agricultural areas in China, but with sparsely measured solar radiation data. The daily sunshine duration are interpolated to the whole area, subsequently, solar radiation are calculated by ?ngstr?m-Prescott model, the generic parameters of which are determined by least square to minimize the overall fitting residual between the ratio of actual to potential sunshine duration and the ratio of actual to extra-terrestrial solar radiation of the sites where solar radiation are available. In other local regions with sparse data, mapping of the solar radiation could be done following the simple procedure. In the present study area, using the interpolated daily sunshine duration data by ANUSPLIN, ?ngstr?m-Prescott model with the generic parameters (a = 0.505, and b = 0.204) returns reasonable results, with the overall RMSE of 2.255 MJ m^?2, and RRMSE of 16.54%. The daily solar radiation varies between 5.26 in December and 22.74 MJ m^?2 in May, and shows an obviously spatial variation which is mainly contributed to the climate and topography. The substitution of solar radiation from nearby station is preferred to estimation by ?ngstr?m-Prescott model if the distance between the stations falls below the threshold of 135 ± 15 km. The RMSE of such substitution increases by approximately 0.157 MJ m^?2 per 10 km.     

Development of GWNU (Gangneung-Wonju National University) one-layer transfer model for calculation of solar radiation distribution of the Korean peninsula

Gangneung-Wonju National University (GWNU) one-layer solar radiation model is developed in order to resolve the lack of the vertical structure of atmospheric components and fast calculation with high horizontal spatial resolution. GWNU model is based on IQBAL and NREL methods and corrected by precise multi-layer Line-By-Line (LBL) model. Further, the amount of solar radiation reaching the surface by using 42 types of vertical atmospheric data as input data was compared with detailed models and one-layer models. One-layer solar radiation models were corrected depending on sensitivity of each input data (i.e., total precipitable water, ozone, mixed gas, and solar zenith angle). Global solar radiation was calculated by corrected GWNU solar model with satellites (MODIS, OMI and MTSAT-2), KLAPS model prediction data in Korea peninsula in 2010, and the results were compared to surface solar radiation observed by 22 KMA solar radiation sites. Calculated solar radiation annually accumulated showed highest solar radiation distribution in Andong, Daegu, and Jinju regions, meanwhile the observation data showed lower solar radiation in Daegu region compared to model result values.     

山东禹城紫外辐射变化特征及其估测方程的建立

本文对2005～2011年山东禹城地区观测得到的紫外辐射的时间变化特征及紫外辐射与总辐射比值的变化特征进行了分析, 并结合气温、降水和露点温度资料建立了禹城地区的紫外辐射估测方程。结果表明:紫外辐射日累计值的变化范围为0.10～1.20 MJ m-2 d-1, 年平均值为0.468 MJ m-2 d-1;紫外辐射日、季节变化规律与总辐射一致, 季节变化都表现为冬季小夏季大, 最小值出现在1月, 最大值出现在6月, 日变化则呈现早晚小中午大的特征;紫外辐射与总辐射的比值范围为0.023～0.046, 其季节变化特征也是冬季小夏季大, 该比值随晴空指数的增大而减小, 而在晴空指数大于0.5时比较稳定。利用温度日较差(日最高气温与最低气温的差值)建立了紫外辐射估测方程, 决定系数R2达0.80, 平均相对误差为0.19, 估测紫外线等级与实测紫外线等级相差不大于1的数据占95%, 该方法可以较好地进行紫外辐射等级的估测。     

Variations and trends in global solar radiation for Turkey

Summary Since measured solar radiation data in Turkey have rather high random errors, sunshine duration data covering the period from 1960 through 1994 from 34 stations in Turkey were taken to derive estimates of monthly mean global solar radiation by a quadratic correlation. The least square linear regression method was applied for trend analysis. Significant negative trends of the annual means were observed with 71 percent of the stations A 3.44 percent decrease in global solar radiation was observed over the last 35 years in Turkey. The decrease in solar radiation is an indication of increased air pollution, as statistical parameters show that Turkey is rapidly expanding economically, and thus air quality has deteriorated correspondingly.With 3 Figures     

Estimating solar radiation on tilted surfaces with various orientations: a study case in Karaj (Iran)

Summary The aim of this study is the evaluation of models that estimate daily global solar radiation on tilted surfaces from that measured on horizontal surfaces. Global solar radiation incident on a tilted plane consists of three components: beam radiation, diffuse radiation and reflected radiation from the ground. The Klein (1977) method, modified by Andersen (1980), was used for estimating direct solar radiation incident on tilted surfaces and an isotropic model was used for estimating reflected solar radiation incident on a tilted plane. In contrast models for the diffuse radiation component show major differences, which justifies a validation study which has been done. Eight models for derivation of daily slope diffuse irradiance from daily horizontal diffuse irradiance were tested against recorded slope irradiances at Karaj (35°55′ N; 50°56′ E), Iran. The following models were included: Badescu (2002), Tian et al. (2001), Reindl et al. (1990), Skartveit and Olseth (1986), Koronakis (1986), Steven and Unsworth (1980), Hay (1979) and Liu and Jordan (1962). All the models use the same method for calculating beam radiation as well as ground reflected radiation. However, only diffuse component of radiation was compared. Statistical indices showed that Reindl’s model gives the most accurate prediction for the south-facing surface and Koronakis’s model performs best for the west-facing surface. The Relative Root Mean Square Errors (%RMSE), except for Steven and Unsworth’s model that has unacceptable results, for whole data range from 1.02 to 10.42%. In general, Reindl’s model produces the best agreement with the measured tilted data.     

A cloud layer‐sunshine model for estimating direct,diffuse and total solar radiation

A previous study (Suckling and Hay, 1976a) described a method for calculating hourly values of the direct and diffuse solar radiation for cloudless sky conditions. This paper presents an extension which incorporates the effects of clouds through the use of hourly values of cloud amount and type for up to four layers and hourly bright sunshine totals. The latter data provide a more accurate measure of the length of time the direct radiation of the sun is not attenuated by cloud. On an average, the cloud layer‐sunshine (CLS) model estimated daily total solar radiation at five Canadian locations to within ±15 per cent of the measured values. This was an improvement over an earlier model (Davies et al., 1975) based on cloud data alone, but the relative advantage, as well as the overall errors themselves, were diminished as the averaging period was increased to five and ten days. The CLS model has the additional advantage of calculating the separate direct and diffuse components of the total solar radiation.     

Problems of determining snow albedo for the high arctic: Research note

Abstract

The measurement of radiation fluxes suffers from inaccuracies at low solar elevations and this poses a problem for determining the snow albedo at high latitudes. From the data of Resolute, NWT, three situations were observed: (1) an often‐reported situation when albedo decreases with increasing solar elevation, (2) an inverse situation when albedo increases with increasing solar elevation and (3) no obvious relationship. There were also cases when albedo exceeded 100%. The possible causes for such anomalous conditions or for erroneous albedos include instrument response deviating from the cosine law, instrument tilt, sensing of the sun by the inverted pyranometer and change in the spectral quality of incoming radiation with changing solar height. However, omission of the radiation values measured during the period of low solar elevation will not seriously affect the prediction of snowmelt. In this note, we have identified the anomalies and suggested possible causes; but further investigations are required to verify the causative mechanisms.