Eddy covariance (EC) systems provide integrated fluxes within their footprint areas. Spatial heterogeneity of up-scaled areas and spatio-temporal mismatches between EC footprint and remote sensing pixels jeopardize the performance of most satellite-based models. To examine the impact of spatial resolution of satellite products on up-scaling of fluxes, we compared the relationships between measured eddy fluxes and enhanced vegetation index (EVI) derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) at 500 and 250 m spatial resolutions, Visible Infrared Imaging Radiometer Suite (VIIRS) at 500 m spatial resolution, and Landsat at 30 m spatial resolution but integrated at the paddock-scale. The experiment was conducted over a grazed native tallgrass prairie pasture, which was divided into nine paddocks for rotational grazing. The EVI data from all satellites showed consistency in detecting vegetation phenology. Seasonality of EC-measured fluxes corresponded well with remotely-sensed vegetation phenology. Approximately 80% of contribution to eddy fluxes came from within 80 m upwind distance of the 2.7 m tall EC tower. As a result, the major contributing area for the measured fluxes was mostly limited to the paddock containing the EC tower. Different timings and duration of grazing caused some heterogeneity among paddocks within the pasture. The EVI of different spatial scales showed strong relationships with CO fluxes. However, Landsat-derived EVI integrated for the paddock containing the EC tower showed substantially stronger relationships with CO fluxes than did MODIS and VIIRS-derived EVI integrated for multiple paddocks, most likely due to similar spatial resolutions of remote sensing and EC observations. Results illustrate that satellite products of fine-scale spatial resolution that are comparable to EC footprints can help improve the performance of satellite-based models for modeling or up-scaling of eddy fluxes, especially in heterogeneous ecosystems.
Monitoring nuclear reactor operations is vital for nuclear safeguards as it ensures that reactors are in compliance with international legal agreements. Validating nuclear facilities and activities, including potential clandestine activities, is currently accomplished by using remotely sensed data from satellites and aircrafts and on-site sampling. However, these techniques are temporally-limited as sampling and interpretation of environmental releases frequently involve labor-intensive, on-site collections.
Rewetted bogs with high water levels (WL) and mire-specific vegetation are crucial carbon (C) sinks, but their function might be threatened by tree encroachment, a phenomenon widespread in the northern hemisphere that often coincides with low WL. This might impact C cycling both at the ecosystem and microform scale in multiple ways, but so far, data are lacking. We established two sites in the same former peat extraction area, one showing permanently high WL and mire-specific vegetation (open site, OS), while the other one has more fluctuating WL and a dense birch ( Ehrh.
Boreal peatlands store vast amounts of soil organic carbon (C) owing to the imbalance between productivity and decay rates. In the recent decades, this carbon stock has been exposed to a warming climate. During the past decade alone, the Arctic has warmed by ∼ 0.
Rewetting peatlands is required to limit carbon dioxide (CO) emissions, however, raising the groundwater level (GWL) will strongly increase the chance of methane (CH) emissions which has a higher radiative forcing than CO. Data sets of CH from different rewetting strategies and natural systems are scarce, and quantification and an understanding of the main drivers of CH emissions are needed to make effective peatland rewetting decisions. We present a large data set of CH fluxes (FCH) measured across 16 sites with eddy covariance on Dutch peatlands.
The Southern Ocean features dynamic mesoscale eddies that significantly influence global biogeochemical cycles, yet their overall effects on biogeochemistry have not been fully explored.
Research aligns these eddies with data from biogeochemical Argo floats, revealing that anticyclonic eddies (AEs) lower dissolved inorganic carbon (DIC) and nitrate, while cyclonic eddies (CEs) increase these concentrations; dissolved oxygen also varies significantly between the two types of eddies.
AEs and CEs play a role in the Southern Ocean's carbon uptake, with AEs contributing 0.01 Pg C while CEs offset this contribution by the same amount, highlighting the need to consider eddy effects in climate models
