scholarly journals Unraveling groundwater contributions to evapotranspiration in a mountain headwaters: Using eddy covariance to constrain water and energy fluxes in the East River Catchment

2021 ◽  
Author(s):  
Anna Ryken ◽  
David Gochis ◽  
Reed Maxwell
Keyword(s):  
Water Balance ◽  
Eddy Covariance ◽  
Energy Flux ◽  
Water Budget ◽  
High Elevation ◽  
Energy Fluxes ◽  
Eddy Covariance Method ◽  
Near Surface ◽  
River Catchment ◽  
East River

Despite the importance of headwater catchments for western United States’ water supply, these regions are often poorly understood, particularly with respect to quantitative understanding of evapotranspiration (ET) fluxes. Heterogeneity of land cover, physiography, and atmospheric patterns in these high-elevation regions lead to difficulty in developing spatially-distributed characterization of ET. As the largest terrestrial water flux behind precipitation, ET represents a significant fraction of the water budget for any watershed. Likewise, groundwater is the largest available freshwater store and has been shown to play a large role in the water balance, even in headwater systems. Using an eddy covariance tower in the East River Catchment, a Colorado River headwaters basin, this study estimates water and energy fluxes in high-elevation, complex systems to better constrain ET estimates and calculate overall water and energy budgets, including losses from groundwater. The eddy covariance method is used to estimate ET from years 2017 through 2019 at a saturated, riparian end-member site. Owing to complexities in near surface atmospheric structure such as stable boundary layers over snowpack and shallow terrain driven flow from surrounding landscape features, energy flux and ET estimates were limited to the warm season when energy closure residuals from the eddy-covariance system were reliably less than 30 %, a threshold commonly used in eddy covariance energy flux estimation. The resulting ET estimations are useful for constraining water budget estimates at this energy-limited site, which uses groundwater for up to 84 % of ET in the summer months. We also compared East River ET magnitudes and seasonality to two other flux towers (Niwot Ridge, CO and Valles Caldera, NM), located in the Rocky Mountains. This data is useful for constraining ET estimates in similar end-member locations across the East River Catchment. Our results show that groundwater-fed ET is a significant component of the water balance and groundwater may supply riparian ET even during low-snow years.

A comparison of methods for determining forest evapotranspiration and its components: sap-flow, soil water budget, eddy covariance and catchment water balance

2001 ◽  
Vol 106 (2) ◽  
pp. 153-168 ◽  
Author(s):  
Kell B Wilson ◽  
Paul J Hanson ◽  
Patrick J Mulholland ◽  
Dennis D Baldocchi ◽  
Stan D Wullschleger
Keyword(s):  
Water Balance ◽  
Soil Water ◽  
Eddy Covariance ◽  
Sap Flow ◽  
Water Budget ◽  
Comparison Of Methods

scholarly journals The Near-Surface Small-Scale Spatial and Temporal Variability of Sensible and Latent Heat Exchange in the Svalbard Region: A Case Study

2012 ◽  
Vol 2012 ◽  
pp. 1-14 ◽  
Author(s):  
Georg Jocher ◽  
Florian Karner ◽  
Christoph Ritter ◽  
Roland Neuber ◽  
Klaus Dethloff ◽  
...  
Keyword(s):  
Eddy Covariance ◽  
Latent Heat ◽  
Small Scale ◽  
Katabatic Wind ◽  
Spatial And Temporal Variability ◽  
Eddy Covariance Method ◽  
Near Surface ◽  
Short Period ◽  
The Village

We present data from two eddy covariance systems for determining the sensible and latent heat flux and the shear stress near the earth's surface. One measures continuously since September 2010 close to the village Ny-Ålesund, Svalbard, the other one was located on Kongsvegen glacier for a short period in April 2011. Two examples for small-scale variability are discussed: near surface external gravity waves associated with katabatic wind from the Broggerbreen glacier located a few kilometres southwestern of Ny-Ålesund, and an episode when the two eddy systems at the different measurement sites captured very different conditions at the same time. In case of gravity wave motion the eddy covariance method results in fictitious positive fluxes due to the strong correlation between temperature and vertical wind, which has to be considered carefully. The comparison between the two sites showed that generally the dynamical processes near the Earth’s surface for Ny-Ålesund and the Kongsvegen glacier are different and local. But there are also cases of synchronization due to synoptic influences, and then the same processes are visible at the two measurement sites. Both examples show that the boundary layer in Ny-Ålesund is not only affected by the main glaciers in the east of the village, but also by other orographical characteristics and synoptic issues. Therefore, the only meaningful way to deal with point measurements is to consider them in context with the surrounding orography and the general meteorological conditions.

Estimating Internal Wave Energy Fluxes in the Ocean

2005 ◽  
Vol 22 (10) ◽  
pp. 1551-1570 ◽  
Author(s):  
Jonathan D. Nash ◽  
Matthew H. Alford ◽  
Eric Kunze
Keyword(s):  
Internal Wave ◽  
Energy Flux ◽  
Wave Energy ◽  
Energy Fluxes ◽  
Near Surface ◽  
Data Limitations ◽  
Pressure Anomaly ◽  
Internal Wave Generation ◽  
Hydrostatic Balance ◽  
Wave Induced

Abstract Energy flux is a fundamental quantity for understanding internal wave generation, propagation, and dissipation. In this paper, the estimation of internal wave energy fluxes 〈u′p′〉 from ocean observations that may be sparse in either time or depth are considered. Sampling must be sufficient in depth to allow for the estimation of the internal wave–induced pressure anomaly p′ using the hydrostatic balance, and sufficient in time to allow for phase averaging. Data limitations that are considered include profile time series with coarse temporal or vertical sampling, profiles missing near-surface or near-bottom information, moorings with sparse vertical sampling, and horizontal surveys with no coherent resampling in time. Methodologies, interpretation, and errors are described. For the specific case of the semidiurnal energy flux radiating from the Hawaiian ridge, errors of ∼10% are typical for estimates from six full-depth profiles spanning 15 h.

scholarly journals Seasonal and Interannual Variations of the Energy Flux Equator and ITCZ. Part II: Zonally Varying Shifts of the ITCZ

2016 ◽  
Vol 29 (20) ◽  
pp. 7281-7293 ◽  
Author(s):  
Ori Adam ◽  
Tobias Bischoff ◽  
Tapio Schneider
Keyword(s):  
Energy Flux ◽  
Order Approximation ◽  
Meridional Overturning Circulation ◽  
Eastern Pacific ◽  
Boreal Winter ◽  
Net Energy ◽  
Energy Fluxes ◽  
Near Surface ◽  
First Order ◽  
Atmospheric Energy

Abstract The ITCZ lies at the ascending branch of the tropical meridional overturning circulation, where near-surface meridional mass fluxes vanish. Near the ITCZ, column-integrated energy fluxes vanish, forming an atmospheric energy flux equator (EFE). This paper extends existing approximations relating the ITCZ position and EFE to the atmospheric energy budget by allowing for zonal variations. The resulting relations are tested using reanalysis data for 1979–2014. The zonally varying EFE is found as the latitude where the meridional component of the divergent atmospheric energy transport (AET) vanishes. A Taylor expansion of the AET around the equator relates the ITCZ position to derivatives of the AET. To a first order, the ITCZ position is proportional to the divergent AET across the equator; it is inversely proportional to the local atmospheric net energy input (NEI) that consists of the net energy fluxes at the surface, at the top of the atmosphere, and zonally across longitudes. The first-order approximation captures the seasonal migrations of the ITCZ in the African, Asian, and Atlantic sectors. In the eastern Pacific, a third-order approximation captures the bifurcation from single- to double-ITCZ states that occurs during boreal spring. In contrast to linear EFE theory, during boreal winter in the eastern Pacific, northward cross-equatorial AET goes along with an ITCZ north of the equator. EFE and ITCZ variations driven by ENSO are characterized by an equatorward (poleward) shift in the Pacific during El Niño (La Niña) episodes, which are associated with variations in equatorial ocean energy uptake.

scholarly journals Predicting evapotranspiration from drone-based thermography – a method comparison in a tropical oil palm plantation

2020 ◽  
Author(s):  
Florian Ellsäßer ◽  
Christian Stiegler ◽  
Alexander Röll ◽  
Tania June ◽  
Alexander Knohl ◽  
...  
Keyword(s):  
Energy Balance ◽  
Eddy Covariance ◽  
Oil Palm ◽  
Method Comparison ◽  
Reference Method ◽  
Net Radiation ◽  
Eddy Covariance Method ◽  
Near Surface ◽  
Oil Palm Plantation ◽  
Deming Regression

Abstract. For the assessment of evapotranspiration, near-surface airborne thermography offers new opportunities for studies with high numbers of spatial replicates and in a fine spatial resolution. We tested drone-based thermography and the subsequent application of three energy balance models (DATTUTDUT, TSEB-PT, DTD) using the widely accepted eddy covariance technique as a reference method. The study site was a mature oil palm plantation in lowland Sumatra, Indonesia. For the 61 flight missions, latent heat flux estimates of the DATTUTDUT model with measured net radiation agreed well with eddy covariance measurements (r² = 0.85; MAE = 47; RMSE = 60) across variable weather conditions and daytimes. Confidence intervals for slope and intercept of a model II Deming regression suggest no difference between drone-based and eddy covariance method, thus indicating interchangeability. TSEB-PT and DTD yielded agreeable results, but all three models are sensitive to the configuration of the net radiation assessment. Overall, we conclude that drone-based thermography with energy-balance modeling is a reliable method complementing available methods for evapotranspiration studies. It offers promising, additional opportunities for fine grain and spatially explicit studies.

scholarly journals Comparison of Actual Evapotranspiration Amounts Estimated Using Water Balance and Eddy-Covariance Methods: Applications to Seolmacheon and Cheongmicheon Basins

2021 ◽  
Vol 21 (2) ◽  
pp. 171-182
Author(s):  
Chulsang Yoo ◽  
Sunguk Song ◽  
Munseok Lee ◽  
Soeun Kim
Keyword(s):  
Water Balance ◽  
Eddy Covariance ◽  
Actual Evapotranspiration ◽  
Annual Data ◽  
Data Sets ◽  
Monthly Variation ◽  
Rainfall Runoff ◽  
Eddy Covariance Method ◽  
Daily Evapotranspiration ◽  
The Difference

In this study, actual evapotranspiration data estimated using the water balance and eddy-covariance methods were compared. Two different basins, i.e., the Seolmacheon and Cheongmicheon basins, were selected, and the actual evapotranspiration was observed using the eddy-covariance method. The rainfall, runoff depth, and actual evapotranspiration data between 2010 and 2018 were collected and analyzed. Daily evapotranspiration data and 10-minute rainfall and runoff data were then accumulated to analyze the annual data. The results showed that the annual actual evapotranspiration amount obtained using the eddy-covariance method was somewhat close to that using the water balance method. This result is interesting, as the monthly variation between the two methods was high. The difference between the actual monthly evapotranspiration and the total loss was not influenced by monthly temperature and rainfall. This tendency was the same throughout the year, but the variation increased during the summer rainy season. In conclusion, both the actual evapotranspiration data estimated using the water balance and eddy-covariance methods can be used as representative annual values for the basins, regardless of the difference between the two data sets.

scholarly journals Impact of spatial resolution on the hydrological simulation of the Durance high-Alpine catchment, France

2001 ◽  
Vol 32 ◽  
pp. 87-92 ◽  
Author(s):  
Pierre Etchevers ◽  
Yves Durand ◽  
Florence Habets ◽  
Eric Martin ◽  
Joël Noilhan
Keyword(s):  
Surface Water ◽  
Water Balance ◽  
Snow Cover ◽  
Spatial Resolution ◽  
Water Budget ◽  
Hydrological Simulation ◽  
Detailed Model ◽  
River Catchment ◽  
The Impact ◽  
Svat Model

AbstractThe water balance of the mountainous Durance river catchment, French Alps, is simulated from 1981 to 1994 with a soil-vegetation-atmosphere transfer (SVAT) model. Particular attention is paid to the snow-cover evolution using a detailed model of the snowpack evolution. The results are validated by comparison of the simulated discharges calculated by the SVAT with daily observations at three gauging stations located in the watershed. Three different spatial resolutions are used (1, 8 and 46 km) in order to evaluate the impact on the surface-water-budget results. Comparison with the finest resolution indicates the need for sub-grid-scale parameterization for the model with larger resolution.

scholarly journals Sensitivity of groundwater recharge using climatic analogues and HYDRUS-1D

2012 ◽  
Vol 16 (8) ◽  
pp. 2485-2497 ◽  
Author(s):  
B. Leterme ◽  
D. Mallants ◽  
D. Jacques
Keyword(s):  
Water Balance ◽  
Groundwater Recharge ◽  
Potential Evapotranspiration ◽  
Future Climate ◽  
Annual Precipitation ◽  
Balance Model ◽  
Subtropical Climate ◽  
Northern Spain ◽  
Near Surface ◽  
Hydrus 1D

Abstract. The sensitivity of groundwater recharge to different climate conditions was simulated using the approach of climatic analogue stations, i.e. stations presently experiencing climatic conditions corresponding to a possible future climate state. The study was conducted in the context of a safety assessment of a future near-surface disposal facility for low and intermediate level short-lived radioactive waste in Belgium; this includes estimation of groundwater recharge for the next millennia. Groundwater recharge was simulated using the Richards based soil water balance model HYDRUS-1D and meteorological time series from analogue stations. This study used four analogue stations for a warmer subtropical climate with changes of average annual precipitation and potential evapotranspiration from −42% to +5% and from +8% to +82%, respectively, compared to the present-day climate. Resulting water balance calculations yielded a change in groundwater recharge ranging from a decrease of 72% to an increase of 3% for the four different analogue stations. The Gijon analogue station (Northern Spain), considered as the most representative for the near future climate state in the study area, shows an increase of 3% of groundwater recharge for a 5% increase of annual precipitation. Calculations for a colder (tundra) climate showed a change in groundwater recharge ranging from a decrease of 97% to an increase of 32% for four different analogue stations, with an annual precipitation change from −69% to −14% compared to the present-day climate.

Physical properties and spatial distribution of the sea ice surface layer (SSL/snow) during the autumn phase of the MOSAiC expedition

2021 ◽  
Author(s):  
Ruzica Dadic ◽  
Martin Schneebeli ◽  
Henna-Reeta Hannula ◽  
Amy Macfarlane ◽  
Roberta Pirazzini
Keyword(s):  
Surface Layer ◽  
Spatial Distribution ◽  
Sea Ice ◽  
Physical Properties ◽  
Surface Scattering ◽  
Climate Feedback ◽  
Energy Fluxes ◽  
Scattering Layer ◽  
Near Surface ◽  
Ice Surface

<p>Snow cover dominates the thermal and optical properties of sea ice and the energy fluxes between the ocean and the atmosphere, yet data on the physical properties of snow and its effects on sea ice are limited. This lack of data leads to two significant problems: 1) significant biases in model representations of the sea ice cover and the processes that drive it, and 2) large uncertainties in how sea ice influences the global energy budget and the coupling of climate feedback. The  MOSAiC research initiative enabled the most extensive data collection of snow and surface scattering layer (SSL) properties over sea ice to date. During leg 5 of the MOSAiC expedition, we collected multi-scale (microscale to 100-m scale) measurements of the surface layer (snow/SSL) over first year ice (FYI) and MYI on a daily basis. The ultimate goal of our measurements is to determine the spatial distribution of physical properties of the surface layer. During leg 5 of the MOSAiC expedition, that surface layer changed from the  surface scattering layer (SSL),   characteristic for the melt season, to an early autumn snow pack. Here,  we will present data showing both a) the physical properties and the spatial distribution of the SSL during the late melt season and b) the transition of the sea ice surface from the SSL to the fresh autumn snowpack. The structural properties of this transition period are poorly documented, and this season is critical  for the initialization of sea ice and snow models. Furthermore, these data are crucial to interpret simultaneous observations of surface energy fluxes, surface optical and remote sensing data (microwave signals in particular), near-surface biochemical activity, and to understand the sea ice  processes that occur as the sea ice transitions from melting to freezing.</p>

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