The accuracy of solar radiation measurements, for direct (DIR)and diffuse (DIF) radiation, depends significantly on the precision of theoperational Sun-tracking device. Thus, rigid targets for instrumentperformance and operation have been specified for international monitoringnetworks, e.g., the Baseline Surface Radiation Network (BSRN)operating under the auspices of the World Climate Research Program (WCRP).Sun-tracking devices that fulfill these accuracy requirements are availablefrom various instrument manufacturers; however, none of the commerciallyavailable systems comprise an automatic accuracy control system allowingplatform operators to independently validate the pointing accuracy ofSun-tracking sensors during operation. Here we present KSO-STREAMS(KSO-SunTRackEr Accuracy Monitoring System),a fully automated, system-independent,and cost-effective system for evaluating the pointing accuracyof Sun-tracking devices. We detail the monitoring system setup, its designand specifications, and the results from its application to the Sun-trackingsystem operated at the KanzelhöheObservatory (KSO) Austrian radiation monitoring network (ARAD) site.The results from an evaluation campaign from March to June2015 show that the tracking accuracy of the device operated at KSO lies within BSRN specifications(i.e., 0.1° tracking accuracy) forthe vast majority of observations (99.8 %). The evaluation of manufacturer-specifiedactive-tracking accuracies (0.02°), during periods withdirect solar radiation exceeding 300 W m, shows that these aresatisfied in 72.9 % of observations. Tracking accuracies are highestduring clear-sky conditions and on days where prevailing clear-skyconditions are interrupted by frontal movement; in these cases, we obtain thecomplete fulfillment of BSRN requirements and 76.4 % of observationswithin manufacturer-specified active-tracking accuracies. Limitations totracking surveillance arise during overcast conditions and periods ofpartial solar-limb coverage by clouds. On days with variable cloud cover,78.1 % (99.9 %) of observations meet active-tracking (BSRN) accuracyrequirements while for days with prevailing overcast conditions thesenumbers reduce to 64.3 % (99.5 %).
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机译：对于直接（DIR）和漫射（DIF）辐射，太阳辐射测量的精度很大程度上取决于可操作的太阳跟踪设备的精度。因此，已经为国际监测网络指定了仪器性能和操作的严格目标，例如在世界气候研究计划（WCRP）的主持下运行的基线表面辐射网络（BSRN）。可以从满足这些准确性要求的太阳跟踪设备中获得各种仪器制造商；然而，市售系统均未包含允许平台操作员在操作期间独立验证太阳跟踪传感器的指向精度的自动精度控制系统。在这里，我们介绍了KSO-STREAMS（KSO-SunTRackEr精度监视系统），它是一个全自动，独立于系统且具有成本效益的系统，用于评估太阳跟踪设备的指向精度。我们详细介绍了监测系统的设置，设计和规格，以及将其应用到Kanzelhöhe天文台（KSO）奥地利辐射监测网络（ARAD）站点运行的太阳跟踪系统中获得的结果.2015年3月至2015年6月的评估活动表明：对于绝大多数观测结果，在KSO上运行的设备的跟踪精度都在BSRN规范之内（即0.1°跟踪精度）。对制造商指定的主动跟踪精度（0.02°）的评估，在太阳直射辐射超过300 W m的时期内，在72.9％的观测值中得到了满足。在晴空条件下以及在主要晴空条件被额头运动打断的日子里，跟踪精度最高。在这种情况下，我们可以完全满足BSRN要求，并在制造商指定的主动跟踪精度内达到观测值的76.4％。跟踪监视的局限性出现在阴天和部分日照被云层覆盖的时期。在云量可变的日子中，有78.1％（99.9％）的观测值满足主动跟踪（BSRN）精度要求，而在普遍阴天的情况下，这些数字减少到64.3％（99.5％）。
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