Oxygen metabolism of intertidal oyster reefs measured by aquatic eddy covariance

2018 ◽  
Vol 599 ◽  
pp. 75-91 ◽  
Author(s):  
MP Volaric ◽  
P Berg ◽  
MA Reidenbach
Keyword(s):  
Eddy Covariance ◽  
Oxygen Metabolism ◽  
Oyster Reefs

Oxygen metabolism and pH in coastal ecosystems: Eddy Covariance Hydrogen ion and Oxygen Exchange System (ECHOES)

2015 ◽  
Vol 13 (8) ◽  
pp. 438-450 ◽  
Author(s):  
Matthew H. Long ◽  
Matthew A. Charette ◽  
William R. Martin ◽  
Daniel C. McCorkle
Keyword(s):  
Eddy Covariance ◽  
Oxygen Metabolism ◽  
Coastal Ecosystems ◽  
Oxygen Exchange ◽  
Hydrogen Ion ◽  
Exchange System

scholarly journals Correction of Eddy Covariance Based Crop ET Considering the Heat Flux Source Area

Atmosphere ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 281
Author(s):  
Stuart L. Joy ◽  
José L. Chávez
Keyword(s):  
Heat Flux ◽  
Eddy Covariance ◽  
Agricultural Land ◽  
Flux Measurement ◽  
Source Area ◽  
Mean Bias Error ◽  
Bias Error ◽  
Crop Water ◽  
The Past ◽  
Measurement Results

Eddy covariance (EC) systems are being used to measure sensible heat (H) and latent heat (LE) fluxes in order to determine crop water use or evapotranspiration (ET). The reliability of EC measurements depends on meeting certain meteorological assumptions; the most important of such are horizontal homogeneity, stationarity, and non-advective conditions. Over heterogeneous surfaces, the spatial context of the measurement must be known in order to properly interpret the magnitude of the heat flux measurement results. Over the past decades, there has been a proliferation of ‘heat flux source area’ (i.e., footprint) modeling studies, but only a few have explored the accuracy of the models over heterogeneous agricultural land. A composite ET estimate was created by using the estimated footprint weights for an EC system in the upwind corner of four fields and separate ET estimates from each of these fields. Three analytical footprint models were evaluated by comparing the composite ET to the measured ET. All three models performed consistently well, with an average mean bias error (MBE) of about −0.03 mm h−1 (−4.4%) and root mean square error (RMSE) of 0.09 mm h−1 (10.9%). The same three footprint models were then used to adjust the EC-measured ET to account for the fraction of the footprint that extended beyond the field of interest. The effectiveness of the footprint adjustment was determined by comparing the adjusted ET estimates with the lysimetric ET measurements from within the same field. This correction decreased the absolute hourly ET MBE by 8%, and the RMSE by 1%.

Altered retinal oxygen metabolism in patients with combined ocular and central nervous system sarcoidosis

Rheumatology ◽  
2020 ◽  
Author(s):  
Astrid Kindt ◽  
Keld-Erik Byg ◽  
Jimmi Wied ◽  
Torkell Ellingsen ◽  
Jesper Rømhild Davidsen ◽  
...  
Keyword(s):  
Oxygen Metabolism ◽  
Cross Sectional Study ◽  
Screening Methods ◽  
Cross Sectional ◽  
Corrected Visual Acuity ◽  
Multi Linear Regression ◽  
The Mean ◽  
Arteriovenous Difference ◽  
Retinal Arteriolar ◽  
Retinal Oximetry

Abstract Objective To evaluate retinal oxygen metabolism by retinal oximetry for ocular and CNS diseases in a cross-sectional study of sarcoidosis. Methods Overall 201 eyes from 103 biopsy-verified sarcoidosis patients were included and divided into four groups depending on the organ affection: (i) sarcoidosis without ocular or CNS affection, (ii) ocular sarcoidosis, (iii) CNS sarcoidosis, and (iv) combined ocular and CNS sarcoidosis. Retinal oximetry was obtained and analysed, with the mean retinal arteriolar and venular saturation as well as arteriovenous difference as principal outcomes. Comparison between groups was done in a multi linear regression model adjusted for age, sex, duration of sarcoidosis, best corrected visual acuity and retinal oximetry quality. Results Mean (s.d.) age was 50.5 (13.4) (95% CI: 47.9, 53.1) years and 52.2% were males. Eyes of the combined Ocular/CNS group had a higher retinal arteriovenous difference than eyes of the Non-ocular/no-CNS group (42.1% vs 37.7%, P = 0.012) but did not differ between other groups. Eyes in the four groups (Non-ocular/no-CNS, Ocular, CNS and Ocular/CNS) did not differ according to retinal arterial (94.5%, 93.5%, 93.5% and 94.5%, respectively) or venular (57.5%, 56.4%, 55.0% and 52.5%, respectively) oxygen saturation. Conclusions The results of this study suggest that eyes of sarcoidosis patients with combined ocular and CNS affection have an altered oxygen metabolism indicating a subclinical eye affection that is not recognized by conventional screening methods.

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