The Baseline Surface Radiation Network and its World Radiation Monitoring Centre
The Earth’s radiation budget is essential for determining the thermal structure of the atmosphere.
The Earth’s radiation budget is essential for determining the thermal structure of the atmosphere, for driving the general circulation of the atmosphere and ocean, and for building the main conditions for the Earth's climate system. Because the Earth's surface transforms more than 50% of the solar radiation that is absorbed by the planet, the irradiances at the Earth's surface are especially important for understanding the climate processes. These irradiances also play an important role in the ocean surface energy budget and thus influence the main features of the ocean currents.
A small change in irradiance at the Earth's surface could result in a significant change in. However, many of the older existing radiometric networks were not capable of arriving at the required accuracy for climate research. At present, our knowledge about the spatial distribution of the radiation is not sufficient for understanding the present climate. This makes the simulation of the past and future climate changes, which could be caused by the changes in radiation, even more uncertain. To help overcome these shortcomings, the radiometric network BSRN was launched in 1992 by WCRP to support the research projects of the WCRP and other scientific programs.
In contrast to the World Radiation Data Center WRDC (http://wrdc-mgo.nrel.gov/), and the Global Energy Balance Archive GEBA (Gilgen et al. 1999), which archive long-time averaged radiation fluxes from more than a thousand sites associated with national weather services, the BSRN/WRMC consists only of a small number of selected research stations, which provide typically 1-minute averaged short- and long-wave surface radiation fluxes of the best possible quality currently available. The surface radiation fluxes are high sampling-rate observations selected from stations within different climate zones of the globe, where collocated surface and upper air meteorological data and other supporting observations are also available. Throughout the BSRN network, the measurements are time-continuous and can be used to:
• monitor the background of the short- and long-wave radiative components
as well as changes using the best methods currently available
• provide datasets for validation and evaluation of satellite-based
measurements of surface radiative fluxes
• produce high-quality observational datasets for the evaluation of climate
model results and for the development of local radiation climatologies
Although the BSRN was originally set up for climate scientists it additionally serves more and mores for photo voltaic and photo thermal applications.
Current state of the WRMC:
As of mid 2013, 58 BSRN stations have submitted data to the WRMC (Fig. 1). The data import is organized in so-called station-to-archive files, which contain all the data from one station collected during one month. Currently a total of over 7000 station-month datasets from 58 stations are available in the WRMC, although only 9 stations have delivered their data back to 1992. The measurements from BSRN stations are expected to be submitted to the WRMC with no more than about one year delay, however, the most recent data from some stations are being submitted with much longer delays. For an overview of available surface radiation data see www.pangaea.de/PHP/BSRN_Status.php.
The WRMC archives many parameters observed at the BSRN stations. Because the stations provide different parameters, the station-to-archive files are organized in logical records (LR) according to various groups of measurements. An overview of all supported LRs and the comprising parameters is given in Table 1. The mandatory parameters are included in the logical record LR 0100; these are global, direct, diffuse, downward long-wave radiation, air temperature, relative humidity, and air pressure at instrument height. Other parameters like the upward radiation fluxes and ancillary data such as upper-air soundings and basic meteorological observations are optional.
The data from the WRMC is stored in PANGAEA – Data Publisher for Earth & Environmental Science (http://www.pangaea.de/). PANGAEA is operated as an Open Access library that is used for archiving, publishing, and distributing geo-referenced data from Earth system research. The main features of PANGAEA are as follows:
• PANGAEA offers a Google-like interface for searching and distributing data
• each dataset from PANGAEA has a bibliographic citation including a Digital
Object Identifier (DOI)
• PANGAEA metadata are searchable e.g. by Google (high ranking)
• PANGAEA provides free software for any PANGAEA derived datasets
Special software is provided at www.pangaea.de/software/. All software is licensed under the General Public License (GPL) and therefore free of charge. A so called BSRN-Toolbox was primarily developed to be used by the staff of the WRMC. Meanwhile, the BSRN-Toolbox is used more and more by station scientists and customers to reformat and test the quality of the BSRN data.
Data quality control
Data submitted to the WRMC runs through an incoming inspection, which includes format checks, visualizations, and the BSRN recommended quality checks V2.0 (Long et al. 2002). Files with detected errors are not imported into the archive but are returned to the submitter. Although these procedures ensure the basic integrity of the data set, it is incumbent on all scientists to do their individual quality checks relevant to their application after extracting BSRN-data.
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