Evapotranspiration over a Japanese cypress forest. I. Eddy covariance fluxes and surface conductance characteristics for 3 years

Kosugi, Yukio; Takanashi, Satoru; Tanaka, Hiroki; Ohkubo, S.; Tani, Makoto; Yano, Masato; Katayama, Tatsuya

doi:10.1016/j.jhydrol.2007.01.039

Cited by 90 publications

(64 citation statements)

References 45 publications

(61 reference statements)

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“…Considering that the eddy covariance method could not perfectly measure ET during and just after rainfall (e.g. Kosugi et al, 2007), we could not validate the simulated intercepted evaporation. Ohta et al (2001) reported that the intercepted evaporation was about 15% of the precipitation at the YLF site, a result + ve 100 100 98 99 99 100 100 99 98 100 98 100 100 104 96 97 108 100 autumn − vf 100 100 103 101 102 100 100 101 104 100 103 100 99 87 101 102 81 100 winter + vg 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 winter − vh 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 Solar spring + sa 101 100 100 100 100 100 100 100 100 100 100 100 104 103 99 100 102 100 Radiation spring − sb 99 100 100 100 100 100 99 100 100 100 100 100 93 97 101 100 98 100 summer + sc 112 102 100 102 100 102 106 100 99 99 97 100 170 124 100 118 136 118 summer − sd 86 98 101 97 100 98 93 100 101 101 103 100 22 70 100 76 50 79 autumn + se 103 101 100 100 100 100 101 100 100 100 100 100 117 111 101 102 108 103 autumn − sf 97 99 100 100 100 99 99 100 100 100 101 100 83 88 99 98 89 95 winter + sg 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 winter − sh 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 which is consistent with the simulated intercepted evaporation value of about 18% of the precipitation.…”

Section: Further Model Improvements and Potential Limitationsmentioning

confidence: 98%

Simulating carbon and water cycles of larch forests in East Asia by the BIOME-BGC model with AsiaFlux data

et al. 2010

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Abstract. Larch forests are widely distributed across many cool-temperate and boreal regions, and they are expected to play an important role in global carbon and water cycles. Model parameterizations for larch forests still contain large uncertainties owing to a lack of validation. In this study, a process-based terrestrial biosphere model, BIOME-BGC, was tested for larch forests at six AsiaFlux sites and used to identify important environmental factors that affect the carbon and water cycles at both temporal and spatial scales.The model simulation performed with the default deciduous conifer parameters produced results that had large differences from the observed net ecosystem exchange (NEE), gross primary productivity (GPP), ecosystem respiration (RE), and evapotranspiration (ET). Therefore, we adjusted several model parameters in order to reproduce the observed rates of carbon and water cycle processes. This model calibration, performed using the AsiaFlux data, substantially improved the model performance. The simulated annual GPP, RE, NEE, and ET from the calibrated model were highly consistent with observed values.The observed and simulated GPP and RE across the six sites were positively correlated with the annual mean air temCorrespondence to: M. Ueyama (miyabi-flux@muh.biglobe.ne.jp) perature and annual total precipitation. On the other hand, the simulated carbon budget was partly explained by the stand disturbance history in addition to the climate. The sensitivity study indicated that spring warming enhanced the carbon sink, whereas summer warming decreased it across the larch forests. The summer radiation was the most important factor that controlled the carbon fluxes in the temperate site, but the VPD and water conditions were the limiting factors in the boreal sites. One model parameter, the allocation ratio of carbon between belowground and aboveground, was site-specific, and it was negatively correlated with the annual climate of annual mean air temperature and total precipitation. Although this study substantially improved the model performance, the uncertainties that remained in terms of the sensitivity to water conditions should be examined in ongoing and long-term observations.

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Section: Further Model Improvements and Potential Limitationsmentioning

confidence: 98%

Simulating carbon and water cycles of larch forests in East Asia by the BIOME-BGC model with AsiaFlux data

et al. 2010

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“…AsiaFlux was established in 1999 as the Asian arm of the worldwide flux research network (FLUXNET) to measure energy, water vapour and CO 2 exchange in Asian region. Although AsiaFlux has been conducting the measurements of water vapour and energy exchanges in a variety of ecosystems, however, most of the studies have examined the seasonal and interannual variations in ET based on the data obtained at single site (e.g., Kumagai et al, 2004;Kosugi et al, 2007;Iida et al, 2009). Matsumoto et al (2008) investigated the ET characteristics at five forest sites of sub-arctic and temperate regions in East Asia.…”

Section: Introductionmentioning

confidence: 99%

“…The McNaughton-Jarvis vegetationatmosphere decoupling coefficient (Ω) has been useful to indicate the relative importance of environmental and physiological factors in controlling dry-canopy ET (McNaughton and Jarvis, 1983). Many previous studies used Ω values for examining the environmental or physiological factors controlling ET worldwide (e.g., Wilson and Baldocchi, 2000;Kumagai et al, 2004;Kosugi et al, 2007;Iida et al, 2009;Jassal et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

Spatial variations in evapotranspiration over East Asian forest sites. I. Evapotranspiration and decoupling coefficient

Khatun

Ohta

Kotani

et al. 2011

Hydrological Research Letters

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Abstract:Evapotranspiration (ET) is not only a vital component of water budget, but also plays an important role in the energy budget of the earth-atmospheric system, ultimately driving many regional and global scale climatological processes. This paper describes the ET characteristics and factors controlling ET across the 17 forest sites in East Asia (2°S to 64°N latitude). ET was measured using the eddy covariance technique at each site. Daytime dry-canopy data for the growing season were used in this study. Growing season mean ET gradually decreased as latitude increased, with a range of 4.4 to 1.2 mm d −1. The growing season mean decoupling coefficient (Ω) ranged from 0.42 to 0.11 across the studied sites. At low-latitude forest sites, Ω was close to 0.50, indicating that the bulk surface was partially decoupled from the atmosphere and ET was strongly controlled by net radiation and vapour pressure deficit. At high-latitude forest sites, Ω was low (~0.12), indicating that the bulk surface was well coupled to the atmosphere and ET was mainly controlled by surface conductance. The value of Ω was determined mainly by the ratio of aerodynamic conductance to surface conductance across the studied forests of East Asia.

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“…They observed drainage flows near the ground surface similar to those by Baldocchi et al (2000a) which biased measurements of CO 2 flux, particularly under stable, stratified conditions. Kosugi et al (2007) used three years of EC measurements to assess the seasonal and inter-annual variations in sensible and latent heat fluxes of a cypress forest with complex topography. Hiller et al (2008) assessed the quality of EC techniques on an alpine grassland in highly complex terrain using energy balance closure techniques and concluded that data quality was generally more consistent when wind direction was along the valley axis as opposed to when winds were transitional.…”

mentioning

confidence: 99%

Surface fluxes and water balance of spatially varying vegetation within a small mountainous headwater catchment

Flerchinger

Marks

Reba

et al. 2010

Hydrol. Earth Syst. Sci.

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Abstract. Precipitation variability and complex topography often create a mosaic of vegetation communities in mountainous headwater catchments, creating a challenge for measuring and interpreting energy and mass fluxes. Understanding the role of these communities in modulating energy, water and carbon fluxes is critical to quantifying the variability in energy, carbon, and water balances across landscapes. The focus of this paper was: (1) to demonstrate the utility of eddy covariance (EC) systems in estimating the evapotranspiration component of the water balance of complex headwater mountain catchments; and (2) to compare and contrast the seasonal surface energy and carbon fluxes across a headwater catchment characterized by large variability in precipitation and vegetation cover. Eddy covariance systems were used to measure surface fluxes over sagebrush (Artemesia arbuscula and Artemesia tridentada vaseyana), aspen (Populus tremuloides) and the understory of grasses and forbs beneath the aspen canopy. Peak leaf area index of the sagebrush, aspen, and aspen understory was 0.77, 1.35, and 1.20, respectively. The sagebrush and aspen canopies were subject to similar meteorological forces, while the understory of the aspen was sheltered from the wind. Missing periods of measured data were common and made it necessary to extrapolate measured fluxes to the missing periods using a combination of measured and simulated data. Estimated cumulative evapotranspiratation from the sagebrush, aspen trees, and aspen understory were 384 mm, 314 mm and 185 mm. A water balance of the catchment indicated that of the 699 mm of areal average precipitation, 421 mm was lost to evapotranspiration, and 254 mm of streamflow was measured from the catchment;Correspondence to: G. N. Flerchinger (gerald.flerchinger@ars.usda.gov) water balance closure for the catchment was within 22 mm. Fluxes of latent heat and carbon for all sites were minimal through the winter. Growing season fluxes of latent heat and carbon were consistently higher above the aspen canopy than from the other sites. While growing season carbon fluxes were very similar for the sagebrush and aspen understory, latent heat fluxes for the sagebrush were consistently higher, likely because it is more exposed to the wind. Sensible heat flux from the aspen tended to be slightly less than the sagebrush site during the growing season when the leaves were actively transpiring, but exceeded that from the sagebrush in May, September and October when the net radiation was not offset by evaporative cooling in the aspen. Results from this study demonstrate the utility of EC systems in closing the water balance of headwater mountain catchments and illustrate the influence of vegetation on the spatial variability of surface fluxes across mountainous rangeland landscapes.

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Evapotranspiration over a Japanese cypress forest. I. Eddy covariance fluxes and surface conductance characteristics for 3 years

Cited by 90 publications

References 45 publications

Simulating carbon and water cycles of larch forests in East Asia by the BIOME-BGC model with AsiaFlux data

Simulating carbon and water cycles of larch forests in East Asia by the BIOME-BGC model with AsiaFlux data

Spatial variations in evapotranspiration over East Asian forest sites. I. Evapotranspiration and decoupling coefficient

Surface fluxes and water balance of spatially varying vegetation within a small mountainous headwater catchment

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