Atmospheric Turbidity over Central North Carolina

Peterson, James T.; Flowers, Edwin C.; Berri, Guillermo J.; Reynolds, C.L.; Rudisill, John H.

doi:10.1175/1520-0450(1981)020<0229:atocnc>2.0.co;2

Cited by 71 publications

(41 citation statements)

References 18 publications

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“…Ten stations in Germany exhibit typical summer maxima and winter minima in turbidity (Table II, Figure 3) that have also been reported in many other mid-latitude locations (e.g. Flowers et al, 1969;Yamashita, 1974;Peterson and Flowers, 1977;Polavarapu, 1978;Sadler, 1978;Peterson et al, 1981;Uboegbulam and Davies, 1983;Louche et al, 1987;Garrison and Sahami, 1995;Gueymard and Garrison, 1998;Pedrós et al, 1999;Holben et al, 2001). Such trends have been attributed to enhanced hygroscopic and photochemical growth of aerosols in summer, as well as enhanced convection due to increased surface heating during the warmer months of the year.…”

Section: Germanymentioning

confidence: 63%

Comparison of aerosol and climate variability over Germany and South Africa

Power

Goyal

2003

Intl Journal of Climatology

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A radiation-based model is employed to evaluate seasonal, interannual, and spatial variability within monthly averaged turbidity (the total column amount of aerosol) at eight stations in South Africa and 13 stations in Germany. Germany has a strong seasonal turbidity trend of summer maxima and winter minima. In South Africa the seasonal turbidity trend is weaker, but, on average, turbidity peaks in spring and is lowest in autumn and winter. Over the last several decades, turbidity over Germany has decreased significantly at seven stations. The impacts of the El Chichón and Pinatubo volcanic eruptions are evident in the turbidity signatures over Germany. Four stations in South Africa show long-term trends in turbidity, but there is no consistent trend. Turbidity in Germany appears to be more influenced by aerosols of non-local origin than in South Africa, where the aerosol load may be of more local origin. Long-term monthly averages ofÅngström's turbidity coefficient β over Germany range between 0.019 and 0.143, and long-term annual averages range between 0.064 and 0.116. Over South Africa, turbidity is noticeably lower: long-term monthly averaged β ranges between 0.004 and 0.071, and the long-term annually averaged β ranges between 0.013 and 0.047. When averaged across all stations in each of the respective countries, turbidity is, on average, between 2.6 and 5.8 times higher in Germany than in South Africa, depending on the time of year.The climate of South Africa is clearly more humid than Germany, although both countries have strong seasonal trends in humidity. South Africa has become more humid over the last several decades. The decrease in turbidity at stations in Germany appears to be due to a reduction in aerosol emissions and/or changes in climatic factors other than humidity.

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Section: Germanymentioning

confidence: 63%

Comparison of aerosol and climate variability over Germany and South Africa

Power

Goyal

2003

Intl Journal of Climatology

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“…First, the marine classification for the sampling site does not imply pure marine air, but rather a modified marine air caused by additional influence from continental and polluted sources between the ocean and the site (the shortest distance between the site and the ocean is about 290 km). Second, the AOD is typically very low during winter months (Peterson et al, 1981). In this study period, the majority of the marine air mass cases occurred during September and early October and the majority of continental air mass cases occurred during late October and November.…”

Section: Retrieval Of Aerosol Radiative Properties In the Southeastermentioning

confidence: 99%

Direct radiative forcing and atmospheric absorption by boundary layer aerosols in the southeastern US: model estimates on the basis of new observations

Zender

Saxena

2001

Atmospheric Environment

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In an effort to reduce uncertainties in the quantification of aerosol direct radiative forcing (ADRF) in the southeastern United States (US), a field column experiment was conducted to measure aerosol radiative properties and effects at Mt. Mitchell, North Carolina, and at an adjacent valley site. The experimental period was from June 1995 to mid-December 1995. The aerosol optical properties (single scattering albedo and asymmetry factor) needed to compute ADRF were obtained on the basis of a procedure involving a Mie code and a radiative transfer code in conjunction with the retrieved aerosol size distribution, aerosol optical depth, and diffuse-to-direct solar irradiance ratio. The regional values of ADRF at the surface and top of atmosphere (TOA), and atmospheric aerosol absorption are derived using the obtained aerosol optical properties as inputs to the column radiation model (CRM) of the community climate model (CCM3). The cloud-free instantaneous TOA ADRFs for highly polluted (HP), marine (M) and continental (C) air masses range from 20.3 to À24.8, 1.3 to À10.4, and 1.9 to À13.4 W m À2, respectively. The mean cloud-free 24-h ADRFs at the TOA (at the surface) for HP, M, and C air masses are estimated to be À8 AE 4 (À33 AE 16), À7 AE 4 (À13 AE 8), and À0.14 AE 0.05 (À8 AE 3) W m À2 , respectively. On the assumption that the fractional coverage of clouds is 0.61, the annual mean ADRFs at the TOA and the surface are À2 AE 1, and À7 AE 2 W m À2 , respectively. This also implies that aerosols currently heat the atmosphere over the southeastern US by 5 AE 3 W m À2 on annual timescales due to the aerosol absorption in the troposphere. #

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“…All daily data for a week are converted as a percentage departure (%) from the weekly average. This method can render weekly cycle evidently and has been carried out by Peterson et al (1981) and Smirnov et al (2002) for weekly analysis on AOD. Similar with the analysis technique for AOD weekly variation by Xia et al (2008) and Quaas et al (2009), we introduce the "weekend effect" to quantify the variable difference between weekdays and weekend.…”

Section: Methodsmentioning

confidence: 99%

Analysis on the impact of aerosol optical depth on surface solar radiation in the Shanghai megacity, China

Shi

et al. 2011

Atmos. Chem. Phys.

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Abstract. This study investigated the decadal variation of the direct surface solar radiation (DiSR) and the diffuse surface solar radiation (DfSR) during in the Shanghai megacity as well as their relationships to Aerosol Optical Depth (AOD) under clear-sky conditions. Three successive periods with unique features of long term variation of DiSR were identified for both clear-sky and all-sky conditions: a "dimming" period from the late 1960s to the mid 1980s, a "stabilization"/"slight brightening" period from the mid 1980s to the mid 1990s, and a "renewed dimming" period thereafter. During the two dimming periods of DiSR, DfSR brightened significantly under clear-sky conditions, indicating that change in atmospheric transparency resulting from aerosol emission has an important role on decadal variation of surface solar radiation (SSR) over this area. The analysis on the relationship between the Moderate-resolution Imaging Spectroradiometer (MODIS) retrieved AOD and the corresponding hourly measurements of DiSR and DfSR under clear-sky conditions clearly revealed that AOD is significantly correlated and anti-correlated with DfSR and DiSR, respectively, both above 99% confidence in all seasons, indicating the great impact of aerosols on SSR through absorption and/or scattering in the atmosphere. In addition, both AOD and the corresponding DiSR and DfSR measured during the satellite passage over Shanghai show obvious weekly cycles. On weekends, AOD is lower than the weekly average, corresponding to higher DiSR and lower DfSR, while the opposite pattern was true for weekdays. Less AOD on weekends due to the reduction of transportation and industrial activities results in enhancement of atmospheric transparency under cloud free conditions so as to increase DiSR and deCorrespondence to: C. Li (ccli@pku.edu.cn) crease DfSR simultaneously. Results show that aerosol loading from the anthropogenic emissions is an important modulator for the long term variation of SSR in Shanghai.

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Atmospheric Turbidity over Central North Carolina

Cited by 71 publications

References 18 publications

Comparison of aerosol and climate variability over Germany and South Africa

Comparison of aerosol and climate variability over Germany and South Africa

Direct radiative forcing and atmospheric absorption by boundary layer aerosols in the southeastern US: model estimates on the basis of new observations

Analysis on the impact of aerosol optical depth on surface solar radiation in the Shanghai megacity, China

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