An overview of the Semi-arid Climate and Environment Research Observatory over the Loess Plateau

Huang, Jianping; Wu, Zhaofei; Zuo, Jinqing; Bi, Jun; Shi, Jun; Wang, Xin; Chang, Zhoulin; Huang, Zhongwei; Yang, Shuangyan; Zhang, Beidou; Wang, Guoyin; Ge, Feng; Yuan, Jiangru; Zhang, Lei; Zuo, Hongchao; Wang, Shigong; Fu, Congbin; Jifan, Chou

doi:10.1007/s00376-008-0906-7

Cited by 262 publications

(135 citation statements)

References 28 publications

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“…In this fragile ecosystem, the net atmosphere-biosphere CO 2 exchange will be less than that observed in forests and croplands, but the sensitivity of the semi-arid ecosystems to extreme environmental conditions that exist at the study site makes it useful for investigating ecosystem response (in terms of CO 2 flux) to changes in solar radiation induced by differing amounts of clouds and aerosols. More details relating to the site and instrumentation can be found in a report by Huang et al (2008).…”

Section: Site Descriptionmentioning

confidence: 99%

The effects of clouds and aerosols on net ecosystem CO<sub>2</sub> exchange over semi-arid Loess Plateau of Northwest China

et al. 2010

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Abstract. The impacts of clouds and atmospheric aerosols on the terrestrial carbon cycle at semi-arid Loess Plateau in Northwest China are investigated, by using the observation data obtained at the SACOL (Semi-Arid Climate and Environment Observatory of Lanzhou University) site. Daytime (solar elevation angles of larger than 50 • ) net ecosystem exchange (NEE) of CO 2 obtained during the midgrowing season (July-August) are analyzed with respect to variations in the diffuse radiation, cloud cover and aerosol optical depth (AOD). Results show a significant impact by clouds on the CO 2 uptake by the grassland (with smaller LAI values) located in a semi-arid region, quite different from areas covered by forests and crops. The light saturation levels in the canopy are low, with a value of about 434.8 W m −2 . Thus, under overcast conditions of optically thick clouds, the CO 2 uptake increases with increasing clearness index (the ratio of global solar radiation received at the Earth surface to the extraterrestrial irradiance at a plane parallel to the Earth surface), and a maximum CO 2 uptake and light use efficiency of vegetation occur with the clearness index of about 0.37 and lower air temperature. Under other sky conditions, CO 2 uptake decreases with cloudiness but light use efficiency is enhanced, due to increased diffuse fraction of PAR. Additionally, under cloudy conditions, changes in the NEE of CO 2 also result from the interactions of many environmental factors, especially the air temperature. In contrast to its response to changes in solar radiation, the carbon uptake shows a slightly negative response to increased AOD. The reason for the difference in the response of the semi-arid grassland from that of the forest and crop lands may be due to the difference in the canopy's architectural structure.

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Section: Site Descriptionmentioning

confidence: 99%

The effects of clouds and aerosols on net ecosystem CO<sub>2</sub> exchange over semi-arid Loess Plateau of Northwest China

et al. 2010

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“…To thoroughly understand the aerosol radiative forcing characteristics in China, numerous surface aerosol experiments have been conducted [17][18][19][20][21][22][23]. However, most of these studies have been conducted in the Beijing-Tianjin-Hebei region [5,15,18,[21][22][23], the Pearl River Delta [14,17,24,25], the Yangtze River Delta [26] and the northwest semi-arid areas [27][28][29]. Observations of aerosol scattering and absorption properties in central China are sparse.…”

Section: Introductionmentioning

confidence: 99%

An Investigation of Aerosol Scattering and Absorption Properties in Wuhan, Central China

et al. 2015

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, and 0.73, respectively. Both σ and σ showed obvious annual variability with large values in winter and small values in summer, principally caused by the annual characteristics of meteorological conditions, especially planetary boundary layer height (PBLH) and local emissions. The SSA showed a slight annual variation. High values of SSA were related to formation of secondary aerosols in winter hazes and aerosol hygroscopic growth in humid summer. The large SSA in June can be attributed to the biomass combustion in Hubei and surrounding provinces. Both σ and σ showed double peak phenomena in diurnal variation resulting from the shallow stable PBLH at night and automobile exhaust emission during morning OPEN ACCESSAtmosphere 2015, 6 504 rush hours. The SSA also exhibited a double peak phenomenon related to the proportional variation of black carbon (BC) and light scattering particulates in the day and night. The long-term exploration on quantified aerosol optical properties can help offer scientific basis of introducing timely environmental policies for local government.

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“…SACOL is located within temperate continental climate zone, and the annual mean air temperature is 6.7 • . The annual precipitation at SACOL is about 381.8 mm, while the annual mean evaporation is about 1528.5 mm (Huang et al, 2008b). POM-01 sky-radiometer has been installed on 15 March 2009 at SACOL to measure the optical properties of aerosols in this region.…”

Section: Introductionmentioning

confidence: 99%

Aerosol optical properties and radiative effect determined from sky-radiometer over Loess Plateau of Northwest China

et al. 2011

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Abstract. The aerosol optical properties and their associated radiative effects are derived from sky-radiometer and surface solar radiation data collected over the Semi-Arid Climate and Environment Observatory of Lanzhou University (SACOL) for the period of March to May (MAM) 2009. The result shows that the seasonal mean aerosol optical depth (AOD) at 500 nm in MAM is 0.40. The single scattering albedo (SSA) at 500 nm in MAM at SACOL fluctuates significantly ranging from 0.82 to 0.98. The averaged value of SSA there for background aerosol is 0.90 in MAM, while it is smaller (0.87) during the dust event outbreak period. The smaller SSA can be interpreted as the result of larger particles during dust events. The averaged asymmetry factor (ASY) at 500 nm during dust event period is 0.73, which is larger than 0.70 of background aerosols. The averaged shortwave radiative effects of the aerosols during dust event period in MAM are 0.68, −70.02 and 70.70 W m −2 , respectively, at the top of the atmosphere (TOA), surface and in the atmosphere. The aerosols heat the atmosphere during dust event period by up to about 2 K day −1 (daily averaged), which is 60 % larger than the heating (1.25 K day −1 ) of background aerosols. The significant heating effect in the atmosphere of the aerosols during dust event is determined by larger AOD and smaller SSA.

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An overview of the Semi-arid Climate and Environment Research Observatory over the Loess Plateau

Cited by 262 publications

References 28 publications

The effects of clouds and aerosols on net ecosystem CO<sub>2</sub> exchange over semi-arid Loess Plateau of Northwest China

The effects of clouds and aerosols on net ecosystem CO<sub>2</sub> exchange over semi-arid Loess Plateau of Northwest China

An Investigation of Aerosol Scattering and Absorption Properties in Wuhan, Central China

Aerosol optical properties and radiative effect determined from sky-radiometer over Loess Plateau of Northwest China

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An overview of the Semi-arid Climate and Environment Research Observatory over the Loess Plateau

Cited by 262 publications

References 28 publications

The effects of clouds and aerosols on net ecosystem CO&lt;sub&gt;2&lt;/sub&gt; exchange over semi-arid Loess Plateau of Northwest China

The effects of clouds and aerosols on net ecosystem CO&lt;sub&gt;2&lt;/sub&gt; exchange over semi-arid Loess Plateau of Northwest China

An Investigation of Aerosol Scattering and Absorption Properties in Wuhan, Central China

Aerosol optical properties and radiative effect determined from sky-radiometer over Loess Plateau of Northwest China

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The effects of clouds and aerosols on net ecosystem CO<sub>2</sub> exchange over semi-arid Loess Plateau of Northwest China

The effects of clouds and aerosols on net ecosystem CO<sub>2</sub> exchange over semi-arid Loess Plateau of Northwest China