This current paper looks at the local cold plasma population found during EMIC waves under different geomagnetic conditions (like looking at the local humidity during different types of weather found around the world). We found that the local cold plasma density is statistically greater when EMIC waves are observed than when they are not. We also found that we didn't observe EMIC waves on strong local negative density gradients.
Now you may be wondering why do we care. If you are a plasma physicist you care because this is interesting to note when looking into the generation of EMIC waves and their ability to resonate with local radiation belt electrons. If you are not a plasma physicist, then you still care... in a big picture kind of way. Our communication systems and technology are susceptible to the effects of geomagnetic activity or weather. EMIC waves can affect the population of particles in space that can cause damage to satellites and when precipitated into the upper atmosphere, change atmospheric chemistry possibly leading to climate changes and may disrupt some communication systems. However, EMIC waves are a relatively localized phenomena and their ultimate impact is still debated. Understanding the conditions under which they occur will hopefully lead to us better understanding their importance in space weather. This, like most of science, is one small step forward.
I hope you enjoy the paper!