Surface flow fields of the global oceans are dominated by so-called mesoscale (50–300 km) eddies. They usually drift westward at a few kilometers per day, transporting mass, temperature, chlorophyll, and debris. There are several methods to identify and track eddies based on satellite measurements, some of them very computationally demanding. Here we extend a recently proposed simple procedure to the global scale, which gives quick coarse-grained statistics on mesoscale vortex properties.

In our laboratory experiments we addressed the question of how surface standing waves in a closed stratified basin are damped by the interaction of the flow in the bulk with a sill-like bottom obstacle reaching up to a density interface between the more saline deep layer and the freshwater layer at the top. We quantify the decay rates of the surface waves and explore what types of internal waves can be excited in this process along the internal density interface.

Mesoscale eddies are ubiquitous swirling flow patterns in the open ocean with diameters of around 100 km. They transport a huge amount of heat and material and are therefore key elements of the “weather” of the ocean. Using satellite-based ocean surface elevation, we found that the combined global effect of all mesoscale eddies can be treated as a single strong “super-vortex”. This finding can be helpful to estimate the energy budget of ocean regions where only sparse field data are available.

The remotely sensed drought severity index (DSI) records compiled by Mu et al. (2013) exhibit significant local trends in several geographic areas. Since the interpretation of DSI values and trends depend on several local factors, standard field significance tests cannot provide more reliable results than the presented local trend survey. The observed continent-wide trends might be related to a slow (decadal) mode of climate variability, a link to global climate change cannot be established.