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Abstract This study investigates the causes of shifts in the subsiding edge of the boreal winter Hadley cell (HC) in response to a comprehensive treatment of ocean surface albedo (OSA) in the fully coupled CESM2. The focus is on an in‐depth understanding of the atmospheric dynamical processes that influence the HC subsiding edge. Two sets of experiments were performed: one utilizing the default OSA, and the other employing the comprehensive OSA that accounts for realistic physical mechanisms. The results show that implementing the comprehensive OSA simulates an El Niño‐like warming pattern in reference to the default experiment, which leads to an HC contraction. Examination of zonal mean momentum dynamics in the upper troposphere reveals that variations in meridional winds, crucial for determining the HC extent, are primarily driven by the differences in the horizontal eddy momentum flux derivative. The findings indicate that the equatorward shift in meridional temperature gradients enhances subtropical zonal winds and baroclinicity along their equatorial flanks, amplifying equatorward‐propagating Rossby waves. This, in turn, alters the eddy momentum flux, reshaping the pattern of the derivatives of horizontal eddy momentum flux, constraining meridional winds, and resulting in the equatorward movement of the HC subsiding edge. A scaling theory further supports the results of the HC contraction, showing that the increased subtropical zonal winds and the equatorward shift of the Intertropical Convergence Zone (ITCZ) elevate the atmospheric angular momentum and eventually limit the expansion of the HC. 

Abstract In this third paper of the series reporting on the reverberation mapping campaign of active galactic nuclei with asymmetric H β emission-line profiles, we present results for 15 Palomar–Green quasars using spectra obtained between the end of 2016–2021 May. This campaign combines long time spans with relatively high cadence. For eight objects, both the time lags obtained from the entire light curves and the measurements from individual observing seasons are provided. Reverberation mapping of nine of our targets has been attempted for the first time, while the results for six others can be compared with previous campaigns. We measure the H β time lags over periods of years and estimate their black hole masses. The long duration of the campaign enables us to investigate their broad-line region (BLR) geometry and kinematics for different years by using velocity-resolved lags, which demonstrate signatures of diverse BLR geometry and kinematics. The BLR geometry and kinematics of individual objects are discussed. In this sample, the BLR kinematics of Keplerian/virialized motion and inflow is more common than that of outflow. 

Abstract We present the first results from the ongoing, intensive, multiwavelength monitoring program of the luminous Seyfert 1 galaxy Mrk 817. While this active galactic nucleus was, in part, selected for its historically unobscured nature, we discovered that the X-ray spectrum is highly absorbed, and there are new blueshifted, broad, and narrow UV absorption lines, which suggest that a dust-free, ionized obscurer located at the inner broad-line region partially covers the central source. Despite the obscuration, we measure UV and optical continuum reverberation lags consistent with a centrally illuminated Shakura–Sunyaev thin accretion disk, and measure reverberation lags associated with the optical broad-line region, as expected. However, in the first 55 days of the campaign, when the obscuration was becoming most extreme, we observe a de-coupling of the UV continuum and the UV broad emission-line variability. The correlation recovered in the next 42 days of the campaign, as Mrk 817 entered a less obscured state. The short C iv and Ly α lags suggest that the accretion disk extends beyond the UV broad-line region.