The Sentinel-6 Michael Freilich altimetry mission flies two GNSS receivers: a primary multi-GNSS (GPS plus Galileo) PODRIX receiver and a GPS-only TriG receiver. Each of these receivers is independently capable of supporting the precise orbit determination (POD) requirement for < 1.5 cm radial rms error. In this study, we characterize the performance of single-receiver solutions and evaluate the benefits of a combined TriG and...

High-precision applications of GNSS require accurate calibrations to correct for phase variations of the transmitting antennas. Calibrations distributed by the International GNSS Service (IGS), based upon observations from the global network of ground stations, are often used as the source of the transmitter calibrations as they are inherently linked to a specific definition of the International Terrestrial Reference Frame. Th...

Estuaries are the receiving environment for catchment‐derived contaminants, the fate of which depends on the interplay between the estuarine geomorphology and hydrodynamics. In large estuaries, biophysical processes are spatially and temporally‐diverse, which makes understanding and managing the impact of human activities challenging. Here we use two common modelling approaches to explore the advantages and limitations of biop...

Summary The floodplain of the Amazon River is a large source for the greenhouse gas methane, but the soil microbial communities and processes involved are little known. We studied the structure and function of the methanogenic microbial communities in soils across different inundation regimes in the Cunia Reserve, encompassing nonflooded forest soil (dry forest), occasionally flooded Igapo soils (dry Igapo), long time flooded...

Summary Tropical lake sediments are a significant source for the greenhouse gas methane. We studied function (pathway, rate) and structure (abundance, taxonomic composition) of the microbial communities (Bacteria, Archaea) leading to methane formation together with the main physicochemical characteristics in the sediments of four clear water, six white water and three black water lakes of the Amazon River system. Concentration...

Summary Methanogenic microbial communities in soil and sediment function only when the environment is inundated and anoxic. In contrast to submerged soils, desiccation of lake sediments happens only rarely. However, some predictions suggest that extreme events of drying will become more common in the A mazon region, and this will promote an increase in sediments drying and exposure. We asked whether and how such methanogenic c...

We studied the methanogenic pathway and archaeal community composition in the sediment of two clearwater lakes, Lake Batata and Lake Mussura, in Amazonia. We measured CH 4 production and δ 13 C of CO 2 , CH 4 , and acetate‐methyl in the presence and absence of CH 3 F, an inhibitor of acetotrophic methanogenesis. The fractionation factor of methanogenesis from CO 2 was rather high in both lake sediments, which was consistent wi...