BROWSE

Related Scientist

Researcher

Axel Timmermann
기후물리 연구단
more info

Drivers of future seasonal cycle changes in oceanic pCO2

Cited 0 time in webofscience Cited 0 time in scopus
65 Viewed 7 Downloaded
Title
Drivers of future seasonal cycle changes in oceanic pCO2
Author(s)
M. Angeles Gallego; Axel Timmermann; Tobias Friedrich; Richard E. Zeebe
Publication Date
2018-09
Journal
Biogeosciences, v.15, no.17, pp.5315 - 5327
Publisher
COPERNICUS GESELLSCHAFT MBH
Abstract
Recent observation-based results show that the seasonal amplitude of surface ocean partial pressure of CO2 (pCO2) has been increasing on average at a rate of 2–3µatm per decade (Landschützer et al. 2018). Future increases in pCO2 seasonality are expected, as marine CO2 concentration ([CO2]) will increase in response to increasing anthropogenic carbon emissions (McNeil and Sasse 2016). Here we use seven different global coupled atmosphere–ocean–carbon cycle–ecosystem model simulations conducted as part of the Coupled Model Intercomparison Project Phase 5 (CMIP5) to study future projections of the pCO2 annual cycle amplitude and to elucidate the causes of its amplification. We find that for the RCP8.5 emission scenario the seasonal amplitude (climatological maximum minus minimum) of upper ocean pCO2 will increase by a factor of 1.5 to 3 over the next 60–80 years. To understand the drivers and mechanisms that control the pCO2 seasonal amplification we develop a complete analytical Taylor expansion of pCO2 seasonality in terms of its four drivers: dissolved inorganic carbon (DIC), total alkalinity (TA), temperature (T), and salinity (S). Using this linear approximation we show that the DIC and T terms are the dominant contributors to the total change in pCO2 seasonality. To first order, their future intensification can be traced back to a doubling of the annual mean pCO2, which enhances DIC and alters the ocean carbonate chemistry. Regional differences in the projected seasonal cycle amplitude are generated by spatially varying sensitivity terms. The subtropical and equatorial regions (40°S–40°N) will experience a  ≈ 30–80µatm increase in seasonal cycle amplitude almost exclusively due to a larger background CO2 concentration that amplifies the T seasonal effect on solubility. This mechanism is further reinforced by an overall increase in the seasonal cycle of T as a result of stronger ocean stratification and a projected shoaling of mean mixed layer depths. The Southern Ocean will experience a seasonal cycle amplification of  ≈ 90–120µatm in response to the mean pCO2-driven change in the mean DIC contribution and to a lesser extent to the T contribution. However, a decrease in the DIC seasonal cycle amplitude somewhat counteracts this regional amplification mechanism.© Author(s) 2018.
URI
https://pr.ibs.re.kr/handle/8788114/4917
ISSN
1726-4170
Appears in Collections:
Center for Climate Physics(기후물리 연구단) > Journal Papers (저널 논문)
Files in This Item:
22. M. Angeles Gallego et al._Drivers of future seasonal cycel changes in oceanic pCO2 (2018).pdfDownload

qrcode

  • facebook

    twitter

  • Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.
해당 아이템을 이메일로 공유하기 원하시면 인증을 거치시기 바랍니다.

Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.

Browse