Sunshine duration(SD) is adopted widely to study global dimming/brightening. However, long-term simultaneous measurements of SD and closely related impact factors require further analysis to elucidate how and why SD h...Sunshine duration(SD) is adopted widely to study global dimming/brightening. However, long-term simultaneous measurements of SD and closely related impact factors require further analysis to elucidate how and why SD has varied during the past decades. In this study, a long-term(1958–2021) SD data series obtained from the Shangdianzi Global Atmosphere Watch(GAW) station in China was analyzed to detect linear trends, climatic jumps, and climatic periods in SD using linear fitting, the Mann–Kendall trend test, and the continuous wavelet transform method. Annual SD exhibited steady dimming(-67.3 h decade-1) before 2010, followed by a period of brightening(189.9 h decade-1)during 2011–2020. An abrupt jump in annual SD occurred in 1995, and the annual SD anomaly exhibited significant oscillation with ~3-yr periodicity during 1960–1978. Partial least squares analysis revealed that annual SD anomaly was associated with variations in relative humidity, gale days, cloud cover, and black carbon(BC). Further analysis of the clear-sky daily sunshine percentage(DSP) and simultaneous measurements of aerosol properties, including aerosol optical depth, aerosol extinction coefficient, single scattering albedo(SSA), BC, and total suspended particulates, suggested that variation in DSP was affected primarily by aerosol scattering and absorption. Furthermore, the hourly clear-sky SD at high aerosol loading was approximately 60% and 56% of that at middle and low aerosol loadings, respectively. The pattern of diurnal variation in clear-sky hourly SD, as well as the actual values, can be affected by the fine particulate concentration, aerosol extinction coefficient, and SSA.展开更多
We used parallel sunshine duration datasets obtained with a Jordan sunshine recorder and three automatic sunshine duration sensors to investigate the differences between these instruments.We used measurements obtained...We used parallel sunshine duration datasets obtained with a Jordan sunshine recorder and three automatic sunshine duration sensors to investigate the differences between these instruments.We used measurements obtained at Shangdianzi(SDZ)regional Global Atmosphere Watch(GAW)station with a Jordan sunshine recorder,a DFC2 photoelectric sunshine meter,a CHP1 pyrheliometer,and two CMP11 pyranometers from 1 January to 5 July 2019 and from 3 November 2020 to 28 February 2021.The results showed that the daily sunshine duration measurements obtained from the Jordan sunshine recorder were comparable with those from the DFC2 meter and the CMP11 pyranometers under all-sky conditions,but were considerably different from those observed by the CHP1 pyrheliometer.An analysis of potential influencing factors showed that the solar zenith angle,the spectral range of the automatic sensors,the relative humidity,and the sky conditions were the main factors affecting the measurements of sunshine duration between the Jordan sunshine recorder and three automatic sensors.We proposed a simple linear regression function-the DFC2-equivalent sunshine duration estimation(DFCESD)model—to guarantee the consistency of the long-term sunshine duration series observed by the Jordan sunshine recorder at SDZ and the measurements from the DFC2 meter.Validation of the DFCESD model showed that the mean absolute difference(MAD)between the daily sunshine duration observed by the Jordan sunshine recorder and those from the DFC2 meter improved from-0.7 to-0.2 h day^(-1),the relative deviation(RD)improved from-9.3%to-2.3%,and the root-mean-square deviation(RMSD)decreased from 1.0 to 0.8 h day^(-1).展开更多
基金Supported by the China Scholarship Council (202205330024)National Key Research and Development Program of China (2017YFB0504002)+1 种基金National Science and Technology Infrastructure Platform Project (2017)Special Fund for Basic Scientific Research of Institute of Urban Meteorology (IUMKY201735)。
文摘Sunshine duration(SD) is adopted widely to study global dimming/brightening. However, long-term simultaneous measurements of SD and closely related impact factors require further analysis to elucidate how and why SD has varied during the past decades. In this study, a long-term(1958–2021) SD data series obtained from the Shangdianzi Global Atmosphere Watch(GAW) station in China was analyzed to detect linear trends, climatic jumps, and climatic periods in SD using linear fitting, the Mann–Kendall trend test, and the continuous wavelet transform method. Annual SD exhibited steady dimming(-67.3 h decade-1) before 2010, followed by a period of brightening(189.9 h decade-1)during 2011–2020. An abrupt jump in annual SD occurred in 1995, and the annual SD anomaly exhibited significant oscillation with ~3-yr periodicity during 1960–1978. Partial least squares analysis revealed that annual SD anomaly was associated with variations in relative humidity, gale days, cloud cover, and black carbon(BC). Further analysis of the clear-sky daily sunshine percentage(DSP) and simultaneous measurements of aerosol properties, including aerosol optical depth, aerosol extinction coefficient, single scattering albedo(SSA), BC, and total suspended particulates, suggested that variation in DSP was affected primarily by aerosol scattering and absorption. Furthermore, the hourly clear-sky SD at high aerosol loading was approximately 60% and 56% of that at middle and low aerosol loadings, respectively. The pattern of diurnal variation in clear-sky hourly SD, as well as the actual values, can be affected by the fine particulate concentration, aerosol extinction coefficient, and SSA.
基金Supported by the National Key Research and Development Program of China(2017YFB0504002)Special Fund for Basic Scientific Research of Institute of Urban Meteorology(2017)。
文摘We used parallel sunshine duration datasets obtained with a Jordan sunshine recorder and three automatic sunshine duration sensors to investigate the differences between these instruments.We used measurements obtained at Shangdianzi(SDZ)regional Global Atmosphere Watch(GAW)station with a Jordan sunshine recorder,a DFC2 photoelectric sunshine meter,a CHP1 pyrheliometer,and two CMP11 pyranometers from 1 January to 5 July 2019 and from 3 November 2020 to 28 February 2021.The results showed that the daily sunshine duration measurements obtained from the Jordan sunshine recorder were comparable with those from the DFC2 meter and the CMP11 pyranometers under all-sky conditions,but were considerably different from those observed by the CHP1 pyrheliometer.An analysis of potential influencing factors showed that the solar zenith angle,the spectral range of the automatic sensors,the relative humidity,and the sky conditions were the main factors affecting the measurements of sunshine duration between the Jordan sunshine recorder and three automatic sensors.We proposed a simple linear regression function-the DFC2-equivalent sunshine duration estimation(DFCESD)model—to guarantee the consistency of the long-term sunshine duration series observed by the Jordan sunshine recorder at SDZ and the measurements from the DFC2 meter.Validation of the DFCESD model showed that the mean absolute difference(MAD)between the daily sunshine duration observed by the Jordan sunshine recorder and those from the DFC2 meter improved from-0.7 to-0.2 h day^(-1),the relative deviation(RD)improved from-9.3%to-2.3%,and the root-mean-square deviation(RMSD)decreased from 1.0 to 0.8 h day^(-1).
