Long‐Term Variability and Tendencies in Mesosphere and Lower Thermosphere Winds From Meteor Radar Observations Over Esrange (67.9°N, 21.1°E).

Long‐term variabilities of monthly zonal (U) and meridional winds (V) in northern polar mesosphere and lower thermosphere (MLT, ∼80–100 km) are investigated using meteor radar observations during 1999–2022 over Esrange (67.9°N, 21.1°E). The summer (June‐August) mean zonal winds are characterized by westward flow up to ∼88–90 km and eastward flow above this height. The summer mean meridional winds are equatorward with strong jet at ∼85–90 km and it weakens above this height. The U and V exhibit strong interannual variability that varies with altitude and month or season. The responses of U and V anomalies (from 1999 to 2003) to solar cycle (SC), Quasi Biennial Oscillation at 10 and 30 hPa, El Niño‐Southern Oscillation, North Atlantic Oscillation, ozone (O3) and carbon dioxide (CO2) are analyzed using multiple linear regression. From analysis, significant regions of correlations between MLT winds and above potential drivers vary with altitude and month. The positive responses of U and V to SC (up to 15 m/s/100 sfu) indicates the strengthening of eastward winds in mid‐late winter, and poleward winds in late autumn and early winter. The O3 likely intensifies the eastward and poleward winds (∼100 m/s/ppmv) in winter and early spring. The CO2 significantly influence the eastward flow in late winter and summer (above ∼90–95 km) and strengthen the meridional circulation. The significant positive trend in U peaks in summer, late autumn and early winter (∼0.6 m/s/year), the negative trend in V is more prominent in summer above ∼90–95 km. Plain Language Summary: The transition region between middle atmosphere and thermosphere is known as the mesosphere and lower thermosphere (MLT). The dynamics and circulation in this region are significant for global transport of important trace chemical species. Further the MLT winds play crucial role for the dynamical coupling of the middle and upper atmosphere. In the present study, the long‐term variability and tendencies in monthly mean zonal and meridional winds are investigated in the Arctic MLT between ∼80 and ∼100 km from meteor radar observations during 1999–2022 over Esrange (67.9°N, 21.1°E) in Sweden. The ability of radar provided the unique, consistent, and long‐term data set of polar MLT winds for duration of about two solar cycles. The MLT winds show important characteristic features and significant interannual variability that vary with altitude and month or season. In addition, the possible influence of climate forcings viz., solar activity, Quasi Biennial Oscillation (at 10 and 30 hPa), El Niño‐Southern Oscillation, North Atlantic Oscillation, ozone, and carbon dioxide on the variabilities of polar MLT winds has been analyzed using multiple linear regression. The significant interannual variabilities and tendencies in northern polar MLT zonal and meridional winds can be attributed to the above potential drivers. Key Points: The long‐term variabilities in arctic mesosphere and lower thermosphere winds in response to potential climate forcings have been investigated for 1999–2022 over EsrangeThe variability in U and V significantly correlated with O3 in winter and early spring, and with CO2 in summer based on altitudeThe interannual variability in U and V is found to vary with altitude and month or season [ABSTRACT FROM AUTHOR]