caa a22 4500 605455597 CHVBK 20210128100213.0 cr unu---uuuuu 210128e20151001xx s 000 0 eng 10.1007/s10872-015-0275-7 doi (NATIONALLICENCE)springer-10.1007/s10872-015-0275-7 Impact of downward heat penetration below the shallow seasonal thermocline on the sea surface temperature [Elektronische Daten] [Shigeki Hosoda, Masami Nonaka, Tomohiko Tomita, Bunmei Taguchi, Hiroyuki Tomita, Naoto Iwasaka] Observational data are used to investigate summer heat penetration into the subsurface ocean in order to quantify the heat capacity of the upper ocean with respect to surface heat exchange. Sea surface temperature is strongly modulated by the change in heat capacity, which could influence the overlying atmosphere and hence trigger climate variations, even during the warming season, when the ocean has been regarded as being rather passive. Few studies have focused on the heat exchange process in surface and subsurface layers because of the existence of a strong seasonal thermocline at the bottom of thin summer mixed layers (ML). By introducing the concept of the heat penetration depth (HPD), defined as the depth to which the downward net heat flux (Q net) distinctly penetrates, we here characterize the heat capacity in terms of the heat content above the HPD using a simple, one-dimensional vertical model during the warming season. Seasonal changes in the HPD indicate that the thermal effects of Q net gradually penetrate below the shallow seasonal thermocline due to vertical eddy diffusivity. Downward heat penetration into the layer below the shallow seasonal thermocline occurs widely throughout the North Pacific, and two-thirds of Q net penetrates below the ML. In a hypothetical analysis of the case where the observed Q net accumulates only within the ML, the change in SST is unrealistically larger than that of the observed SST. These results indicate that heat penetration plays a crucial role in climate variations during the warming season. The Oceanographic Society of Japan and Springer Japan, 2015 Heat capacity nationallicence Seasonal variability nationallicence North Pacific nationallicence Argo nationallicence J-OFURO2 nationallicence Air-sea interaction nationallicence Hosoda Shigeki Research and Development Center for Global Change, Japan Agency for Marine-Earth Science and Technology, 2-15 Natsushima-cho, 237-0061, Yokosuka, Kanagawa, Japan aut Nonaka Masami Application Laboratory, Japan Agency for Marine-Earth Science and Technology, Yokohama, Japan aut Tomita Tomohiko Graduate School of Science and Technology, Kumamoto University, Kumamoto, Japan aut Taguchi Bunmei Application Laboratory, Japan Agency for Marine-Earth Science and Technology, Yokohama, Japan aut Tomita Hiroyuki Hydrospheric Atmospheric Research Center, Nagoya University, Nagoya, Japan aut Iwasaka Naoto Faculty of Marine Technology, Tokyo University of Marine Science and Technology, Tokyo, Japan aut Journal of Oceanography Springer Japan 71/5(2015-10-01), 541-556 0916-8370 71:5<541 2015 71 10872 https://doi.org/10.1007/s10872-015-0275-7 text/html Onlinezugriff via DOI BK010053 XK010053 XK010000 Metadata rights reserved Springer special CC-BY-NC licence nationallicence 1 research-article jats NATIONALLICENCE NATIONALLICENCE NL-springer NATIONALLICENCE 856 40 https://doi.org/10.1007/s10872-015-0275-7 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Hosoda Shigeki Research and Development Center for Global Change, Japan Agency for Marine-Earth Science and Technology, 2-15 Natsushima-cho, 237-0061, Yokosuka, Kanagawa, Japan aut NATIONALLICENCE 700 1- Nonaka Masami Application Laboratory, Japan Agency for Marine-Earth Science and Technology, Yokohama, Japan aut NATIONALLICENCE 700 1- Tomita Tomohiko Graduate School of Science and Technology, Kumamoto University, Kumamoto, Japan aut NATIONALLICENCE 700 1- Taguchi Bunmei Application Laboratory, Japan Agency for Marine-Earth Science and Technology, Yokohama, Japan aut NATIONALLICENCE 700 1- Tomita Hiroyuki Hydrospheric Atmospheric Research Center, Nagoya University, Nagoya, Japan aut NATIONALLICENCE 700 1- Iwasaka Naoto Faculty of Marine Technology, Tokyo University of Marine Science and Technology, Tokyo, Japan aut NATIONALLICENCE 773 0- Journal of Oceanography Springer Japan 71/5(2015-10-01), 541-556 0916-8370 71:5<541 2015 71 10872