气候变化领域集成服务门户(CCPortal): Energy and mass exchange at an urban site in mountainous terrain

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DOI	10.5194/acp-22-6559-2022
	Energy and mass exchange at an urban site in mountainous terrain - the Alpine city of Innsbruck
	Ward, Helen Claire; Rotach, Mathias Walter; Gohm, Alexander; Graus, Martin; Karl, Thomas; Haid, Maren; Umek, Lukas; Muschinski, Thomas
发表日期	2022
ISSN	1680-7316
EISSN	1680-7324
起始页码	6559
结束页码	6593
卷号	22 期号:10 页码:35
英文摘要	This study represents the first detailed analysis of multi-year, near-surface turbulence observations for an urban area located in highly complex terrain. Using 4 years of eddy covariance measurements over the Alpine city of Innsbruck, Austria, the effects of the urban surface, orographic setting and mountain weather on energy and mass exchange are investigated. In terms of surface controls, the findings for Innsbruck are in accordance with previous studies at city centre sites. The available energy is partitioned mainly into net storage heat flux and sensible heat flux (each comprising about 40 % of the net radiation, Q* , during the daytime in summer) The latent heat flux is small by comparison (only about 10% of Q*) due to the small amount of vegetation present but increases for short periods (6-12 h) following rainfall. Additional energy supplied by anthropogenic activities and heat released from the large thermal mass of the urban surface helps to support positive sensible heat fluxes in the city all year round. Annual observed CO2 fluxes (5.1 kg C M-2 yr(-1)) correspond well to modelled emissions and expectations based on findings at other sites with a similar proportion of vegetation. The net CO2 exchange is dominated by anthropogenic emissions from traffic in summer and building heating in winter. In contrast to previous urban observational studies, the effect of the orography is examined here. Innsbruck's location in a steep-sided valley results in marked diurnal and seasonal patterns in flow conditions. A typical valley wind circulation is observed (in the absence of strong synoptic forcing) with moderate up-valley winds during daytime, weaker down-valley winds at night (and in winter) and near-zero wind speeds around the times of the twice-daily wind reversal. Due to Innsbruck's location north of the main Alpine crest, southerly foehn events frequently have a marked effect on temperature, wind speed, turbulence and pollutant concentration. Warm, dry foehn air advected over the surface can lead to negative sensible heat fluxes both inside and outside the city. Increased wind speeds and intense mixing during foehn (turbulent kinetic energy often exceeds 5 m(2) s(-2)) help to ventilate the city, illustrated here by low CO2 mixing ratios. Radiative exchange is also affected by the orography - incoming shortwave radiation is blocked by the terrain at low solar elevation. The interpretation of the dataset is complicated by distinct temporal patterns in flow conditions and the combined influences of the urban environment, terrain and atmospheric conditions. The analysis presented here reveals how Innsbruck's mountainous setting impacts the near-surface conditions in multiple ways, highlighting the similarities with previous studies in much flatter terrain and examining the differences in order to begin to understand interactions between urban and orographic processes.
学科领域	Environmental Sciences; Meteorology & Atmospheric Sciences
语种	英语
WOS研究方向	Environmental Sciences & Ecology ; Meteorology & Atmospheric Sciences
WOS记录号	WOS:000800911900001
来源期刊	ATMOSPHERIC CHEMISTRY AND PHYSICS
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/273150
作者单位	University of Innsbruck
推荐引用方式 GB/T 7714	Ward, Helen Claire,Rotach, Mathias Walter,Gohm, Alexander,et al. Energy and mass exchange at an urban site in mountainous terrain - the Alpine city of Innsbruck[J],2022,22(10):35.
APA	Ward, Helen Claire.,Rotach, Mathias Walter.,Gohm, Alexander.,Graus, Martin.,Karl, Thomas.,...&Muschinski, Thomas.(2022).Energy and mass exchange at an urban site in mountainous terrain - the Alpine city of Innsbruck.ATMOSPHERIC CHEMISTRY AND PHYSICS,22(10),35.
MLA	Ward, Helen Claire,et al."Energy and mass exchange at an urban site in mountainous terrain - the Alpine city of Innsbruck".ATMOSPHERIC CHEMISTRY AND PHYSICS 22.10(2022):35.