Search for: All records

Eddy covariance has revolutionized our understanding of ecosystem-atmosphere interactions. Multiple studies have characterized the climate space occupied by flux tower networks, but none to our knowledge have characterized if eddy covariance sites represent the global distribution of soil characteristics that are critical for determining ecosystem function or studied the distances between towers to apply ‘paired’ tower studies. Of 1233 global eddy covariance towers explored here, half had a nearest neighbor within 10 km. Soil database pixels with towers have nearly 20% more silt and 8% less sand than the global soil texture distribution, with more soil N (0.58 g/kg vs. 0.38 g/kg) and organic C (8.3 g/kg vs. 5.4 g/kg), and 10% greater cation exchange capacity in upper layers than pixels without towers. Global syntheses of eddy covariance towers should be cognizant that tower networks capture more fertile soils than the terrestrial surface on average. A logical way to improve global representativeness is to further build collaborations and invest in underrepresented regions. 

Abstract We present JWST/MIRI-MRS observations of ISO-Oph 37, a highly inclined flat-spectrum (≲1 Myr old) source, to investigate the chemical composition and dynamical origin of its inner-disk gas. The spectrum reveals a rich combination of molecular emission and absorption: H₂O, CO, and OH are detected in emission, while strong absorption is observed from CO, H₂O, CO₂, HCN, C₂H₂, and CH₄, with no detectable ice absorption features. Local thermodynamic equilibrium slab modeling of the absorption yields excitation temperatures ofT_ex ∼ 400–600 K and column densities of $\log N/{\mathrm{cm}}^2\sim 16$ –19, characteristic of warm gas located within the inner few astronomical unit. The absorption lines are significantly blueshifted relative to the systemic velocity, with mid-IR lines exhibiting larger shifts than near-IR CO absorption. This velocity structure points to a velocity- and temperature-stratified molecular disk wind. In this framework, the absorption directly samples disk material lifted from the inner disk surface, preserving the chemical imprint of the wind-launching region. Along the line of sight, ISO-Oph 37 is unusually hydrocarbon-rich compared to other known absorption systems (GV Tau N and IRS 46), exhibiting high (C₂H₂+CH₄)/HCN, (C₂H₂+CH₄)/CO, and H₂O/CO column density ratios, while the CO and HCN columns remain broadly typical. We find that these molecular ratios are best explained by enhancement of both hydrocarbons and water, driven by inward drift and sublimation of icy pebbles and by thermal processing of carbonaceous grains at the soot line. ISO-Oph 37 thus demonstrates that carbon-rich inner-disk chemistry can be established early in disk evolution and that it can be directly probed through molecular absorption in disk winds.