Assessment of BSRN radiation records for the computation of monthly means
The accuracy of the Baseline Surface Radiation Network (BSRN) radiation monthly averages are assessed by investigating data gap frequency due to missing or discarded high time resolution data. The monthly statistics, especially means are considered to be important and useful values for climate research, model performance evaluations and for assessing the quality of satellite computations. The study investigates the spread in different algorithms that have been applied for the computation of monthly means from minute values. We found that a substantial fraction of the radiation fluxes observed at BSRN sites is either missing or flagged as questionable. The percentage of missing data is 4.4%, 13.0%, and 6.5% for global radiation, direct shortwave radiation, and downwelling longwave radiation, respectively. Most flagged data in the shortwave are due to nighttime instrumental noise and can reasonably be set to zero after correcting for thermal offsets in the daytime data. The paper reveals that the computation of monthly means from 1-minute observations distinctly depends on the selected method. The intra-method difference generally increases with an increasing fraction of missing data. The study demonstrates that the handling of flagged data clearly impacts on monthly mean estimates obtained with different methods. We showed that the spread of monthly shortwave fluxes are generally clearly higher than for downwelling longwave radiation. Overall, BSRN observation provide sufficient accuracy and completeness for reliable estimates of monthly mean values. However, we should aim at further increasing the data quality by reducing the data gap frequency and the number of outliers. The authors suggest using a standardized method for the computation of monthly means in order to avoid a mismatch of published monthly mean radiation fluxes from BSRN.
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC05-76RL01830
- OSTI ID:
- 1008226
- Report Number(s):
- PNNL-SA-64085; KP1701000; TRN: US201106%%338
- Journal Information:
- Atmospheric Measurement Techniques, 4(2):339-354, Vol. 4, Issue 2
- Country of Publication:
- United States
- Language:
- English
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