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Effects of the soil heat flux Estimates on Surface Energy Balance Closure over a Semi-Arid Grassland

Acta meteorologica Sinica 2011年第6期25卷 774-782页

作者：岳平张强牛生杰成华王西育 Key Laboratory of Arid Climatic Change and Disaster Reduction of Gansu Province Institute of Arid MeteorologyChina Meteorological Administration Zhangye National Climatological Observatory Nanjing University of Information Science & Technology

soil heat flux is important for surface energy balance （SEB）, and inaccurate estimation of soil heat flux often leads to surface energy imbalance. In this paper, by using observations of surface radiation fluxes and soil temperature gradients at a semi-arid grassland in Xilingguole, Inner Mongolia, China from June to September 2008, the characters of the SEB for the semi-arid grassland were analyzed. Firstly, monthly averaged diurnal variations of SEB components were revealed. A 30-min forward phase displacement of soil heat flux （G） observed by a fluxplate at the depth of 5-em below the soil surface was conducted and its effect on the SEB was studied. Secondly, the surface soil heat flux （Gs） was computed by using harmonic analysis and the effect of the soil heat storage between the surface and the fluxplate on the SEB was examined. The results show that with the 30-min forward phase displacement of observed G, the slope of the ordinary linear regression （OLR） of turbulent fluxes （H＋LE） against available energy （Rn G） increased from 0.835 to 0.842, i.e., the closure ratio of SEB increased by 0.7%, yet energy imclosure of 15.8% still existed in the SEB. When Gs, instead of G was used in the SEB equation, the slope of corresponding OLR of （H＋LE） against （Rn-Gs） reached 0.979, thereby the imelosure ratio of SEB was reduced to only 2.1%.

关键词： soil heat flux surface energy balance harmonic analysis turbulent fluxes available energy

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Biophysical warming patterns of an open-top chamber and its short-term influence on a Phragmites wetland ecosystem in China

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China Geology 2023年第4期6卷 594-610页

作者： Xue-yang Yu Si-yuan Ye Li-xin Pei Liu-juan Xie Ken W.Krauss Samantha K.Chapman Hans Brix Key Laboratory of Coastal Wetland Biogeosciences Qingdao Institute of Marine GeologyChina Geological SurveyMinistry of Natural ResourcesQingdao 266071China Institute of Marine Science and Technology Shandong UniversityQingdao 266237China Wetland and Aquatic Research Center U.S.Geological SurveyLafayette 70506United States of America Department of Biology Villanova UniversityVillanova 19085United States of America Department of Biology Aarhus UniversityAarhus 8000CDenmark

Passive-warming, open-top chambers(OTCs) are widely applied for studying the effects of future climate warming on coastal wetlands. In this study, a set of six OTCs were established at a Phragmites wetland located in the Yellow River Delta of Dongying City, China. With data collected through online transmission and in-situ sensors, the attributes and patterns of realized OTCs warming are *** authors also quantified the preliminary influence of experimental chamber warming on plant *** produced an elevated average air temperature of 0.8°C(relative to controls) during the growing season(June to October) of 2018, and soil temperatures actually decreased by 0.54°C at a depth of 5 cm and 0.46°C at a depth of 30 cm in the OTCs. Variations in diel patterns of warming depend greatly on the heat sources of incoming radiation in the daytime versus soil heat flux at night. Warming effects were often larger during instantaneous analyses and influenced OTCs air temperatures from-2.5°C to 8.3°C dependent on various meteorological conditions at any given time, ranging from cooling influences from vertical heat exchange and vegetation to radiation-associated warming. Night-time temperature depressions in the OTCs were due to the low turbulence inside OTCs and changes in surface soilatmosphere heat transfer. Plant shoot density, basal diameter, and biomass of Phragmites decreased by23.2%, 6.3%, and 34.0%, respectively, under experimental warming versus controls, and plant height increased by 4.3%, reflecting less carbon allocation to stem structures as plants in the OTCs experienced simultaneous wind buffering. While these passive-warming OTCs created the desired warming effects both to the atmosphere and soils, pest damages on the plant leaves and lodging within the OTCs were extensive and serious, creating the need to consider control options for these chambers and the replicated OTCs studies underway in other Chinese Phragmites marshes(Panjin and Yancheng).

关键词： Open-top chambers(OTCs)warming Phragmites australis wetland Short-term ecosystem impact Climate warming soil heat flux soil-atmosphere heat transfer Ecological geological engineering Hydrogeological engineering Yellow River Delta

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Estimation of ground heat flux and its impact on the surface energy budget for a semi-arid grassland

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Research in Cold and Arid Regions 2011年第1期3卷 41-50页

作者： JinQing Zuo JieMin Wang JianPing Huang WeiJing Li GuoYin Wang HongLi Ren Key Laboratory for Semi-Arid Climate Change of the Ministry of Education College of Atmospheric Sciences Lanzhou University Lanzhou Gansu 730000 China Laboratory for Climate Studies China Meteorological Administration Beijing 100081 China Cold and Arid Regions Environmental and Engineering Research Institute Chinese Academy of Sciences Lanzhou Gansu 730000 China

Three approaches, i.e., the harmonic analysis （HA） technique, the thermal diffusion equation and correction （TDEC） method, and the calorimetric method used to estimate ground heat flux, are evaluated by using observations from the Semi-Arid Climate and Environment Observatory of Lanzhou University （SACOL） in July, 2008. The calorimetric method, which involves soil heat flux measurement with an HFP01SC self-calibrating heat flux plate buried at a depth of 5 cm and heat storage in the soil between the plate and the surface, is here called the ITHP approach. The results show good linear relationships between the soil heat fluxes measured with the HFP01SC heat flux plate and those calculated with the HA technique and the TDEC method, respectively, at a depth of 5 cm. The soil heat fluxes calculated with the latter two methods well follow the phase measured with the HFP01SC heat flux plate. The magnitudes of the soil heat flux calculated with the HA technique and the TDEC method are close to each other, and they are about 2 percent and 6 percent larger than the measured soil heat flux, respectively, which mainly occur during the nighttime. Moreover, the ground heat fluxes calculated with the TDEC method and the HA technique are highly correlated with each other （R2= 0.97）, and their difference is only about 1 percent. The TDEC-calculated ground heat flux also has a good linear relationship with the ITttP-calculated ground heat flux （R2 = 0.99）, but their difference is larger （about 9 percent）. Furthermore, compared to the HFP01SC direct measurements at a depth of 5 cm, the ground heat flux calculated with the HA technique, the TDEC method, and the ITHP approach can improve the surface energy budget closure by about 6 percent, 7 percent, and 6 percent at SACOL site, respectively. Therefore, the contribution of ground heat flux to the surface energy budget is very important for the semi-arid grassland over the Loess Plateau in China. Using turbulent heat fluxes with common

关键词： soil heat flux harmonic analysis TDEC method self-calculating heat flux plate surface energy budget

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