Low-frequency variability and teleconnections during Northern Hemisphere winters captured by satellite microwave brightness temperature observations

A long-term climate dataset of daily global middle-troposphere satellite microwave temperature sounding observations of brightness temperature is first utilized to statistically analyze atmospheric variability in 22 individual winters from 1998-1999 to 2019-2020. Analysis of the temporal variability in the observations reveals a significant synoptic variability with 3-5 and 10-day time periods, an intraseasonal low-frequency variability that occurs on the time scales of 1-3 months, an interannual variability dominated by ENSO-related phenomena in the tropical Pacific, as well as a few sharp bands at one year, half year, 3-4 months. The same dataset is then used for examining if satellite microwave brightness temperature observations can directly capture teleconnections during Northern Hemisphere winters. Temporal correlation coefficients of the observed monthly mean brightness temperature variability between all possible pairs of grid points in the Northern Hemisphere exhibit five well-known teleconnection patterns that were identified within global reanalysis datasets in early studies in the 80's. They are the eastern Atlantic pattern, the Pacific/North American pattern, the western Atlantic pattern, the western Pacific pattern, and the Eurasian pattern. Our results suggest a detectable weather and climate of the atmosphere and call a direct application of satellite observations for studying weather and climate.