Sea ice and atmospheric circulation shape the high-latitude lapse rate feedback

Abstract

Arctic amplification of anthropogenic climate change is widely attributed to the sea-ice albedo feedback, with its attendant increase in absorbed solar radiation, and to the effect of the vertical structure of atmospheric warming on Earth’s outgoing longwave radiation. The latter lapse rate feedback is subject, at high latitudes, to a myriad of local and remote influences whose relative contributions remain unquantified. The distinct controls on the high-latitude lapse rate feedback are here partitioned into “upper” and “lower” contributions originating above and below a characteristic climatological isentropic surface that separates the high-latitude lower troposphere from the rest of the atmosphere. This decomposition clarifies how the positive high-latitude lapse rate feedback over polar oceans arises primarily as an atmospheric response to local sea ice loss and is reduced in subpolar latitudes by an increase in poleward atmospheric energy transport. The separation of the locally driven component of the high-latitude lapse rate feedback further reveals how it and the sea-ice albedo feedback together dominate Arctic amplification as a coupled mechanism operating across the seasonal cycle.

Cold‐Season Arctic Amplification Driven by Arctic Ocean‐Mediated Seasonal Energy Transfer

“…However, the cold‐season increases in surface air temperature and humidity in sea‐ice retreat regions seen in the control AMIP experiment are not captured in the Clim_Polar AMIP experiment (Figures S11 and S12), demonstrating the influence of sea‐ice reduction and ocean heat uptake/release on cold‐season downward LW radiative flux at the surface. Furthermore, the ensemble‐mean TOA LW flux change associated with the lapse‐rate change is markedly dampened in the Clim_Polar AMIP experiment (Figures 6c and 6g), supporting the argument that the lapse‐rate feedback is tied to sea ice reduction and related sea‐ice feedbacks (Boeke et al., 2020; Feldl et al., 2017, 2020; Graversen et al., 2014). This dampening is especially pronounced in sea‐ice retreat regions where a substantial amount of heat is released from the ocean into the atmosphere mainly in the form of surface turbulent heat fluxes in the control AMIP and coupled model simulations (Figures 6d and 6h).…”

Local and Remote Atmospheric Circulation Drivers of Arctic Change: A Review

“…A further question concerns the vertical distribution of moisture transport in the Arctic atmosphere and its impact on amplification and near-surface warming. Corridors of direct moisture advection from the mid-latitudes to the Arctic tend to ascend from the surface to the middle troposphere along moist isentropes (Laliberté and Kushner, 2014;Wernli and Papritz, 2018;Hao et al, 2021), andFeldl et al (2020) find that greater warming and moistening of the upper troposphere does not directly contribute to Arctic amplification as it does not affect the near-surface lapse rate feedback. However, transport of moist air masses from the mid-latitude near-surface layer to the Arctic middle and upper troposphere likely still contributes to Arctic warming indirectly, as latent heat release aids the formation of blocking anticyclones (Pfahl et al, 2015;Grams and Archambault, 2016;Zhang and Wang, 2018;Sánchez et al, 2020) that deflect cyclones poleward (Papritz and Dunn-Sigouin, 2020) and warm the lower troposphere through subsidence (Laliberté and Kushner, 2014;Ding et al, 2017;Wernli and Papritz, 2018;Papritz, 2020).…”

“…Arctic blocking is less studied than in the midlatitudes, and future studies should ensure that any blocking detection algorithms employed in this emerging area of research are suitable to detect Arctic blocks, which are generally weaker than their mid-latitude counterparts and may not be detected by geopotential height-based algorithms (see Blocking Definition, Identification, and Northern Hemisphere Climatology), that require poleward westerlies (Tyrlis et al, 2020). The vertical structure of moisture transport should be carefully examined in relation to blocking and influences on warming, as Arctic moistening in lower levels likely contributes directly to the lapse rate feedback, while middle-and upper-tropospheric moisture transport may contribute to warming through more indirect pathways including latent heat release and blocking development, and/or may act to dampen Arctic amplification due to a negative upper-level lapse rate feedback (Feldl et al, 2020;Hao et al, 2021). The relative importance of and relationships between lower-latitude and within-Arctic processes during Arctic warming events should also be further investigated.…”

“…The earliest-identified cause of enhanced warming is the icealbedo (or surface-albedo) feedback, whereby some initial warming reduces polar ice and snow cover and causes a greater fraction of incoming solar radiation to be absorbed, which further accelerates warming and albedo reduction (Budyko, 1969;Cess et al, 1991;Serreze et al, 2009). Other local feedback processes that may contribute to enhanced warming in the absence of extra-Arctic influence include the lapse rate and Planck feedbacks (Manabe and Wetherald, 1975;Crook et al, 2011;Pithan and Mauritsen, 2014;Hahn et al, 2020;Previdi et al, 2020), as well as cloud and water vapor feedbacks (Graversen and Wang, 2009;Cox et al, 2015;Kay et al, 2016;Södergren et al, 2018;Huang et al, 2019;Feldl et al, 2020;Middlemas et al, 2020) in an atmosphere moistened by sea ice decline (Boisvert et al, 2015;Jun et al, 2016;Taylor et al, 2018;Rinke et al, 2019b). Extra-Arctic processes, in particular changes to largescale atmospheric and oceanic circulation and related changes in poleward atmospheric moist and dry static energy transport (e.g., Yang et al, 2010;Alexeev and Jackson, 2013;Zhang et al, 2013;Graversen and Burtu, 2016;Yoshimori et al, 2017), also contribute to Arctic amplification and are entangled with intra-Arctic feedbacks in complex ways.…”

“…This in turn amplifies the lapse rate feedback, which can be understood as a manifestation of accentuated lower-tropospheric warming dictated by the surface temperature change (Boeke et al, 2021). Feldl et al (2020) and Boeke et al (2021) argue that Arctic amplification should be attributed to the physical processes that establish the nonuniform vertical warming profile producing the lapse rate feedback, rather than the lapse rate feedback per se.…”