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Baseline Surface Radiation Network

Baseline Surface Radiation Network
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Baseline Surface Radiation Network World Climate Research Programme An overview of the requirements and operational issues Derived from the BSRN Operations Manual Version 2.1 Clive Lee Customer Services Specialist Kipp & Zonen B.V.

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Introduction The BSRN manual represents the highest quality of solar radiation measurement currently achievable using commercially available equipment. The individual user may not wish to apply to join the BSRN and may not share the speciﬁc objectives of the BSRN. Reasons of cost, location and local equipment preferences may restrict the ability to fully comply with all the requirements. However, the Manual still represents an excellent guide to best practice in the establishment of a ‘reference’ quality solar radiation monitoring station. This overview is adapted from the BSRN Operations...

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Overall Goals and Purpose of the BSRN The original concept for the BSRN developed from the needs of both the climate change and satellite validation communities. The initial plan for a global network of radiation stations was developed by the WCRP Working Group on Radiative Fluxes (WGRF) in 1989, and reﬁned at two workshops on the implementation of the BSRN, in Washington, DC in December 1990, and in Davos, Switzerland in August 1991. The formal goals and objectives were set down as follows: • To provide data for calibrating satellite-based estimates of the surface radiation budget (SRB)...

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BSRN The associated activities and research goals are: • Site Characterization: Acquisition of quantitative information on features such as the nature of the surface, average cloud cover and type, aerosols, etc., that characterize the site for satellite applications. • Infrared Irradiance Measurements: Advancing state-of-the-art instrumentation and methods of observation for accurate measurement of down-welling radiance and irradiance measurements to meet Surface Radiation Budget (SRB) measurement standards. • Extended-Surface Reﬂectance and In-situ Measurements: Development of methods for...

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BSRN Diﬀuse Solar Radiation • The pyranometer must be ventilated. • The dome and detector must be completely shaded by a ball or disk on the sun tracker. • The shading must be equivalent to a 5° ﬁeld of view. • The pyranometer body temperature must be monitored. Sun Tracker • The sun tracker for the pyrheliometer must have a positioning accuracy of ± 0.1° or better. • Active tracking using a 4-element ‘quadrant’ sun sensor is recommended. • The sun tracker must be capable of also mounting an Absolute Cavity Radiometer when required for periodic calibration of the pyrheliometer and...

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Data Acquisition System Instruments should be connected to diﬀerential inputs of the data acquisition system to minimise oﬀsets within the system. Measurement Sampling Frequency All radiation variables shall be sampled at 1 Hz with an averaging time of one minute. The ﬁnal output for each variable should consist of: • One-minute mean • Minimum • Maximum • Standard deviation Some instruments may require the measurement of more than one signal for the calculation of a speciﬁc radiation element (e.g. for applying a ‘correction’ to the readings) but the archived data will consist only of the...

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Location of Site In selecting sites for the Baseline Surface Radiation Network, the objective is to choose a site which is representative of a relatively large area (greater than 100 km²) with common features. The site location should be consistent with the intended purpose for which the observations are being made. For example, a site which has a unique microclimate within a larger region should not be selected as a site for regional climate observations. This is particularly important for stations with the Expanded Measurement Programme measuring reﬂected solar radiation and up-welling...

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BSRN Six-monthly Maintenance • Calibrate pyranometers and pyrheliometer with the ACR. Swap the global and diﬀuse pyranometers. • Calibrate the pyrgeometers. • Replace any items showing signs of deterioration (e.g. cables). • Check ventilation unit ﬁlters and clean or replace as necessary (more frequent inspection may be necessary in dusty environments. • Check seals of weatherproof enclosures, apply grease if necessary. • Service sun tracker as recommended by the manufacturer. Annual Maintenance • Calibrate Absolute Cavity Radiometer. • Loosen, lubricate and retighten all ﬁxings,...

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BSRN Pyranometers The CMP 21 and CMP 22 Pyranometers meet all the requirements of BSRN. They have high quality waterproof connectors for ease of exchange and calibration. The desiccant cartridge can be simply unscrewed and the highly accurate bubble level can be seen without removing the clip-on sun shield. The CMP 21 is a scientiﬁc standard pyranometer with precision glass domes for very good cosine response. It is supplied as standard with a 10K Thermistor body temperature sensor and individually measured temperature dependence for the instrument sensitivity. Each unit has the directional...

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BSRN Kipp & Zonen usually supplies the COMBILOG 1020 data logger from Friedrichs in Germany (shown in the picture). This is easy to programme and has a built-in display and function control, performance is broadly similar to the Campbell CR 1000. In all cases the data loggers require weatherproof enclosures, power supplies with back-up and a means of communication for downloading the data (this could be hard-wired, GSM modem, satellite modem, etc). Absolute Cavity Radiometer (ACR) The only ACRs currently available commercially are the Eppley HF and AHF models and the PMO 6, developed and...

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The Baseline Surface Radiation Network (BSRN) Sponsored by, or associated with:

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Passion for Precision Kipp & Zonen is the leading company in measuring solar We promise our customers guaranteed performance and radiation and atmospheric properties. Our passion for quality in; Meteorology, Climatology, Hydrology, Industry, precision has led to the development of a large range of Renewable Energy, Agriculture and Public Health. high quality instruments, from all weather radiometers to complete measurement systems. We hope you will join our passion for precision. HEAD OFFICE Kipp & Zonen B.V. Delftechpark 36, 2628 XH Delft P.O. Box 507, 2600 AM Delft The Netherlands SALES...

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