Understanding Arctic Moisture Intrusion Events through Novel Climatology

Moisture and heat transport events across the Arctic play a vital role in modulating the Arctic climate and determining sea ice variability. As the sea ice has retreated and thinned in recent decades, it may be becoming more vulnerable to atmospheric forcings. Moisture intrusions, the transport of intense moisture channels into the Arctic, can affect sea ice through the formation of clouds and associated precipitation. Radiative changes associated with clouds, water vapor, and precipitation can impact the surface energy balance (SEB) and sea ice mass balance. The lifecycles and distribution of these events and how they may be changing over time is still not well understood.

This study develops a novel tracking algorithm to identify and track moisture intrusion events through the Arctic. We introduce a detailed climatology of events between 1979-2022 using ERA5 northward water vapor flux and total column water vapor reanalysis data. The climatology is then used to analyze the characteristics of Arctic moisture intrusions. The analysis reveals a clear seasonality in moisture intrusion events and contrasting behavior between intrusions from the Atlantic and Pacific regions. The new database shows that intrusion frequency is greatest in the summer and lowest in the winter with large annual variation. Events originating from the Atlantic tend to be larger in size and longer in duration than their Pacific counterparts. The tracker and subsequent moisture intrusion event database allows us to improve our knowledge of these events and examine how they are changing over time with climate change. The database enables future work investigating atmosphere-sea ice interactions including how moisture intrusions impact the SEB and sea ice conditions.