USAP-DC

This project will use observations and coupled climate model simulations to examine the causes of sea ice variability. Sea ice in the Southern Ocean has increased in area over the observational record but researchers have yet to agree on the cause. Researchers suggests that changes in surface winds, upper-ocean freshening, or internal ocean/atmosphere variability could be the main driver for the increase in sea ice area. This project will determine how much of the change in sea ice area from year to year is due to oceanic, atmospheric, and radiative processes. Reconciling the observation-based understanding with model representations of sea ice variability will improve confidence in projections of future changes in Southern Ocean sea ice. The goal of this proposal is to improve our understanding of the processes that drive Southern Ocean sea ice year-to-year variability and long term trends. This knowledge will provide insight into how Southern Ocean sea ice responded to greenhouse gas and ozone forcing in the past and how it will respond in the future. The energy budget of the coupled cryosphere/ocean/atmosphere climate system will be used as a framework to disentangle drivers and responses during sea ice loss events. The technique consists of: (i) calculating the coupled energy budget of the climate system at the monthly timescale, (ii) isolating the radiative impact of sea ice variability from the radiative impact of cloud variability in the observed satellite radiation record and (iii) analyzing the vertical structure of atmospheric energy transport to determine the vertical profile of energy transport into the atmospheric column. This framework will allow the investigators to distinguish whether ice loss events are triggered by oceanic processes, atmospheric dynamics, or radiative processes. Preliminary results show that a diversity of mechanisms can drive Southern Ocean sea ice variability in coupled climate models whereas observed sea ice variability appears to be dominated by atmospheric dynamics. The exploration of biases between models and observations in both the mean state and in specific processes will yield more accurate projections of the future of sea ice in the Southern Ocean.

Person	Role
Donohoe, Aaron	Investigator and contact
Schweiger, Axel	Co-Investigator

Antarctic Ocean and Atmospheric Sciences

Award # 1643436

USAP-1643436_1

None in the Database

Repository	Title (link)	Format(s)	Status
USAP-DC	Partionining of CERES planetary albedo between atmospheric and surface reflection	Matlab	exists

1. Donohoe, A., Blanchard-Wrigglesworth, E., Schweiger, A., & Rasch, P. J. (2020). The Effect of Atmospheric Transmissivity on Model and Observational Estimates of the Sea Ice Albedo Feedback. Journal of Climate, 33(13), 5743–5765. (doi:10.1175/jcli-d-19-0674.1)
2. 2021 Cardinale, C.J., B.E.J. Rose, A.L. Lange and A. Donohoe. Stratospheric and tropospheric flux contributions to the polar cap energy budgets. J. Climate. 34 (11), 4261-4278. (doi:10.1175/JCLI-D-20-0722.1)
3. Hahn, L. C., K.C. Armour, M.D. Zelinka, C. M. Bitz, and A. Donohoe, 2021: Contributions to Polar Amplification in CMIP5 and CMIP6 Models. 9. Frontiers in Earth Science, 9. 2296-6463. (doi:10.3389/feart.2021.710036)
4. 2021 Cox, T., A. Donohoe, K.C. Armour and G.H Roe. Radiative and dynamic controls on meridional heat transport under altered rotation rate. Journal of Climate. (doi:10.1175/JCLI-D-20-0533.1)
5. 2019 Vargas Zeppetello, L.R, A. Donohoe and D.S. Battisti. Does surface temperature respond to or determine downwelling longwave radiation?. Geophysical Research Letters. (doi:10.1175/JCLI-D-19-0329.1)
6. 2020 Donohoe, A., E. Blanchard-Wrigglesworth., A. Schweiger, P. Rasch. The effect of atmospheric transmissivity on model and observational estimates of the sea ice albedo feedback. Journal of Climate. 33 (13), 5743-5765. (doi:10.1175/JCLI-D-19-0674.1)
7. 2020 Donohoe, A., K.C. Armour, G.H. Roe and D.S. Battisti. The partitioning of atmospheric energy transport and changes under climate forcing in coupled climate models. Journal of Climate. 33 (10), 4141-4165. (doi:10.1175/JCLI-D-19-0797.1)
8. 2020 Hahn, L., K.C. Armour, D.S Battisti and A. Donohoe. Understanding Asymmetries in Arctic and Antarctic Lapse-Rate Feedbacks and Polar Amplification. Geophysical Research Letters. 47 (16) e2020GL088965. (doi:10.1029/2020GL088965.)
9. 2021 Blanchard-Wrigglesworth, E. L. Roach, A. Donohoe and Q. Ding Impact of winds on Antarctic sea ice trends and variability. Journal of Climate. 34 (3), 949-965. (doi:10.1175/JCLI-D-20-0386.1)
10. Blanchard‐Wrigglesworth, E., A. Donohoe, L. A. Roach, A. DuVivier, and C. M. Bitz, 2021: High‐Frequency Sea Ice Variability in Observations and Models. 48. (14). Geophysical Research Letters, 48. 0094-8276. (doi:10.1029/2020GL092356)