Direct advection measurements do not help to solve the night-time CO2 closure problem: Evidence from three different forests

Aubinet, Marc; Feigenwinter, Christian; Heinesch, Bernard; Bernhofer, Christian; Canepa, Elisa; Lindroth, Anders; Montagnani, Leonardo; Rebmann, Corinna; Sedlák, Pavel; Gorsel, Eva van

doi:10.1016/j.agrformet.2010.01.016

Cited by 137 publications

(126 citation statements)

References 46 publications

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“…In fact, wind measurements inside the canopy can be severely influenced by very local conditions, limiting their spatial representativeness. Furthermore, as stated by Aubinet et al (2010), the spatial resolution of the CO 2 measurement system as well was not sufficient to take small-scale field heterogeneities into account. Therefore, major uncertainties can be attributed to under-representativeness of the samplings.…”

Section: Resultsmentioning

confidence: 99%

Application of a mass consistent flow model to study the CO2 mass balance of forests

Canepa

Georgieva

Manca

et al. 2010

Agricultural and Forest Meteorology

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The reconstruction of the wind field is one of the main issues in the mass conservation approach for calculation of CO 2 advection in forest ecosystems and still remains a challenging problem. In the current study, we present an advancement of this approach: the use of a mass consistent flow model (WINDS) which takes into account measured wind data and simulates the 3-D flow field, while imposing air mass conservation in the control volume. We apply the WINDS model to calculate half hourly mean total advective flux terms at the arboEurope-IP site of Renon (Bozen/Bolzano Autonomous Province), in Northern Italy. The data used refer to six time periods of one day representing three different meteorological conditions observed during the ADVEX campaign from April to September 2005. Current results are compared with results obtained in two other studies for the same time periods. One of these studies is based on the mass conservation approach as well, but applies only interpolations to reconstruct the wind field; the other study makes use of tilt correction (sectorwise planar fit method) for the vertical wind component. In the present study, the effect of the wind field reconstruction method on the estimation of the advective fluxes is discussed. The possibility of using reduced input wind data (i.e. number of towers) for WINDS is also investigated. The results suggest that the representativeness of wind tower measurements is of primary importance for estimating CO 2 advection terms and their uncertainty in complex terrain.

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Section: Resultsmentioning

confidence: 99%

Application of a mass consistent flow model to study the CO2 mass balance of forests

Canepa

Georgieva

Manca

et al. 2010

Agricultural and Forest Meteorology

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“…However, the accuracy of EC measurements of NEE has been questioned particularly over tall vegetation in complex terrains [2][3][4][5][6][7] and even over various forests with relative flat terrains [7,8]. One of the key factors that results in uncertainties in measuring scalar exchanges between the atmosphere and forests is the complexity of airflow above and within the forest canopy [4,[9][10][11].…”

Section: Introductionmentioning

confidence: 99%

Wind Regimes above and below a Temperate Deciduous Forest Canopy in Complex Terrain: Interactions between Slope and Valley Winds

Wang

2014

Atmosphere

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Abstract:The thermally driven wind over mountainous terrains challenges the estimation of CO2 exchange between forests and the atmosphere when using the eddy covariance technique. In this study, the wind regimes were investigated in a temperate deciduous forested valley at the Maoershan site, Northeast China. The wind direction above the canopy was preferentially up-valley in the daytime and down-valley in the nighttime, corresponding to the diurnal patterns of above-canopy temperature gradient and stability parameter. In both leaf-on and -off nighttime, a down-valley flow with a maximum velocity of 1~3 m•s −1 was often developed at 42 m above the ground (2.3-fold of the canopy height). However, the below-canopy prevailing wind was down-slope in the night, contrast to the below-canopy temperature lapse and unstable conditions. This substantial directional shear illustrated shallow slope winds were superimposed on larger-scale valley winds. As a consequence, the valley-wind component becomes stronger with increasing height, indicating a clear confluence of drainage flow to the valley center. In the daytime, the below-canopy wind was predominated down-slope due to the temperature inversion and stable conditions in the leaf-on season, and was mainly up-valley or down-slope in the leaf-off season. The isolation of momentum flux and OPEN ACCESSAtmosphere 2015, 6 61 radiation by the dense canopy played a key role in the formation of the below-canopy unaligned wind and inverse stability. Significant lateral kinematic momentum fluxes were detected due to the directional shear. These findings suggested a significant interaction between slope and valley winds at this site. The frequent vertical convergence / divergence above the canopy and horizontal divergence/convergence below the canopy in the nighttime / daytime is likely to induce significant advections of trace gases and energy flux.

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“…7;Aubinet et al, 2012, р. 400-401] на протяжении последних лет существует консенсус относительно высокого качества оценок метода микровихревых пульсаций, хотя и отмечаются проблемы, связанные с измерением потоков ночью, крупномасштабными вихрями и незамкнутостью теплового баланса [Finnigan, 2008;Aubinet et al, 2010]. Для доказательства вышеупомянутого вывода диссертанту необходимо было провести оценку того, насколько точно измеряемые камерным методом величины УП метана позволяют оценивать эмиссию метана из экосистем на масштабе, на котором работает метод микровихревых пульсаций и показать, что эта оценка точнее, чем даваемая методом микровихревых пульсаций.…”

Section: используемые сокращенияunclassified

Thesis of N.A. Shnyrev: I. Micrometeorology and other notes

Sabrekov¹,

Glagolev²

2016

Environmental Dynamics and Global Climate Change

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Настоящая работа посвящена разбору некоторых на наш взгляд спорных и дискуссионных положений, высказанных в диссертации Николая Андреевича Шнырева «Режимные наблюдения и оценка газообмена на границе почвы и атмосферы (на примере потоков метана болотного стационара среднетаежной зоны Западной Сибири “Мухрино”)». Поскольку затронутые в диссертации методологические вопросы являются чрезвычайно важными для такой актуальной темы как оценка баланса парниковых газовых для наземных экосистем, корректности их трактовки необходимо уделять повышенное внимание. Ключевыми поднятыми в диссертации в этом контексте являются вопросы о применимости и работе микрометеорологических методов как альтернативных по отношению к классическим камерным. Рассмотрены критика этих методов Н.А. Шныревым, введённая диссертантом новая кассификация методов измерения газообмена на границе почвы и атмосферы, а также ряд вопросов, связанных с историей изучения эмиссии метана болотами Западной Сибири и методологией работы различных методов.

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Direct advection measurements do not help to solve the night-time CO2 closure problem: Evidence from three different forests

Cited by 137 publications

References 46 publications

Application of a mass consistent flow model to study the CO2 mass balance of forests

Application of a mass consistent flow model to study the CO2 mass balance of forests

Wind Regimes above and below a Temperate Deciduous Forest Canopy in Complex Terrain: Interactions between Slope and Valley Winds

Thesis of N.A. Shnyrev: I. Micrometeorology and other notes

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