Global transpiration data from sap flow measurements: The SAPFLUXNET database

Plant transpiration links physiological responses of vegetation to water supply and demand with hydrological, energy, and carbon budgets at the land-atmosphere interface. However, despite being the main land evaporative flux at the global scale, transpiration and its response to environmental drivers are currently not well constrained by observations. Here we introduce the first global compilation of whole-plant transpiration data from sap flow measurements (SAPFLUXNET, https://sapfluxnet.creaf.cat/, last access: 8 June 2021). We harmonized and quality-controlled individual datasets supplied by contributors worldwide in a semi-automatic data workflow implemented in the R programming language. Datasets include sub-daily time series of sap flow and hydrometeorological drivers for one or more growing seasons, as well as metadata on the stand characteristics, plant attributes, and technical details of the measurements. SAPFLUXNET contains 202 globally distributed datasets with sap flow time series for 2714 plants, mostly trees, of 174 species. SAPFLUXNET has a broad bioclimatic coverage, with woodland/shrubland and temperate forest biomes especially well represented (80% of the datasets). The measurements cover a wide variety of stand structural characteristics and plant sizes. The datasets encompass the period between 1995 and 2018, with 50% of the datasets being at least 3 years long. Accompanying radiation and vapour pressure deficit data are available for most of the datasets, while on-site soil water content is available for 56% of the datasets. Many datasets contain data for species that make up 90% or more of the total stand basal area, allowing the estimation of stand transpiration in diverse ecological settings. SAPFLUXNET adds to existing plant trait datasets, ecosystem flux networks, and remote sensing products to help increase our understanding of plant water use, plant responses to drought, and ecohydrological processes. SAPFLUXNET version 0.1.5 is freely available from the Zenodo repository (10.5281/zenodo.3971689; Poyatos et al., 2020a). The "sapfluxnetr"R package-designed to access, visualize, and process SAPFLUXNET data-is available from CRAN. © 2021 Rafael Poyatos et al.This research was supported by the Minis-terio de Economía y Competitividad (grant no. CGL2014-55883-JIN), the Ministerio de Ciencia e Innovación (grant no. RTI2018-095297-J-I00), the Ministerio de Ciencia e Innovación (grant no. CAS16/00207), the Agència de Gestió d’Ajuts Universitaris i de Recerca (grant no. SGR1001), the Alexander von Humboldt-Stiftung (Humboldt Research Fellowship for Experienced Researchers (RP)), and the Institució Catalana de Recerca i Estudis Avançats (Academia Award (JMV)). Víctor Flo was supported by the doctoral fellowship FPU15/03939 (MECD, Spain)

Towards long-term standardised carbon and greenhouse gas observations for monitoring Europe's terrestrial ecosystems : a review

Research infrastructures play a key role in launching a new generation of integrated long-term, geographically distributed observation programmes designed to monitor climate change, better understand its impacts on global ecosystems, and evaluate possible mitigation and adaptation strategies. The pan-European Integrated Carbon Observation System combines carbon and greenhouse gas (GHG; CO2, CH4, N2O, H2O) observations within the atmosphere, terrestrial ecosystems and oceans. High-precision measurements are obtained using standardised methodologies, are centrally processed and openly available in a traceable and verifiable fashion in combination with detailed metadata. The Integrated Carbon Observation System ecosystem station network aims to sample climate and land-cover variability across Europe. In addition to GHG flux measurements, a large set of complementary data (including management practices, vegetation and soil characteristics) is collected to support the interpretation, spatial upscaling and modelling of observed ecosystem carbon and GHG dynamics. The applied sampling design was developed and formulated in protocols by the scientific community, representing a trade-off between an ideal dataset and practical feasibility. The use of open-access, high-quality and multi-level data products by different user communities is crucial for the Integrated Carbon Observation System in order to achieve its scientific potential and societal value.Peer reviewe

Climate control of terrestrial carbon exchange across biomes and continents

Peer reviewe

Viscous correction and shock reflection in stunted Busemann intakes

Air intakes play a crucial role in hypersonic air-breathing propulsion by compressing incoming airflow to high pressure and temperature for combustion. Axisymmetric Busemann intakes can achieve highly efficient compression for scramjet engines in inviscid flow. In practice, however, viscous effects exert significant influence on the flowfield and performance of scramjet intakes, necessitating effective methods for viscous correction and intake shortening. The present study develops a robust correction methodology by coupling viscous flow simulations with a wall correction method based on local displacement thickness of the boundary layer, whose edge is detected based on the total enthalpy profile. This iterative correction process is applied to hypersonic stunted Busemann intakes and supersonic M-flow ring geometries. Flow features in the initial inviscid fields are successfully reproduced in the presence of viscosity for both applications, except for highly stunted Busemann intakes, where the mode transition to Mach reflection occurs at different shortening lengths

Shock reflection in axisymmetric internal flows

The flow downstream of an axisymmetric conical shock wave, with a downstream pointing apex, can be predicted by solving the Taylor-Maccoll equations. Previous research, however, has suggested that these theoretical flowfields are not fully realisable in practice, and that a Mach reflection forms towards the centreline of the flow. This phenomenon is investigated for the case where the freestream Mach number is 3.0 and the shock angle is 150. A range of complementary prediction techniques that include the solution to the Taylor-Maccoll equations, the method of characteristics, curved shock theory and CFD, are used to gain insight into this flow. The case where a cylindrical centrebody is placed along the axis of symmetry is studied for several values of centrebody radius that are expected to produce regular reflection at the centrebody surface. An analysis of pressure gradients suggests that the flowfield downstream of the reflected shock does not contribute to the process of transition from regular to Mach reflection at these conditions

Competing Agendas in Upstream Engagement Meetings Between Celiac Disease Experts and Patients

This article examines discussions between innovators and patient users about emergent medical technologies in the field of celiac disease. Using discursive psychology and conversation analysis, the authors analyze participants’ talk with regard to the social activities performed. They find that the topical agenda, preference structure, and presuppositions incorporated in the innovators’ questions restrict patients’ scope for saying things in and on their own terms. Not participants’ intentions per se but what the questions indirectly communicate profoundly shapes the agenda of these meetings. This may explain why some of the difficulties of innovator-user interaction are persistent and hard to pinpoint