Impact of Antarctic mixed-phase clouds on climate
- SPEC Incorporated, Boulder, CO 80301, and
- National Center for Atmospheric Research, Boulder, CO 80307
Precious little is known about the composition of low-level clouds over the Antarctic Plateau and their effect on climate. In situ measurements at the South Pole using a unique tethered balloon system and ground-based lidar reveal a much higher than anticipated incidence of low-level, mixed-phase clouds (i.e., consisting of supercooled liquid water drops and ice crystals). The high incidence of mixed-phase clouds is currently poorly represented in global climate models (GCMs). As a result, the effects that mixed-phase clouds have on climate predictions are highly uncertain. In this paper, we modify the National Center for Atmospheric Research (NCAR) Community Earth System Model (CESM) GCM to align with the new observations and evaluate the radiative effects on a continental scale. The net cloud radiative effects (CREs) over Antarctica are increased by +7.4 Wm–2, and although this is a significant change, a much larger effect occurs when the modified model physics are extended beyond the Antarctic continent. The simulations show significant net CRE over the Southern Ocean storm tracks, where recent measurements also indicate substantial regions of supercooled liquid. Finally, these sensitivity tests confirm that Southern Ocean CREs are strongly sensitive to mixed-phase clouds colder than –20 °C.
- Research Organization:
- SPEC Inc., Boulder, CO (United States); National Center for Atmospheric Research (NCAR), Boulder, CO (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Biological and Environmental Research (BER)
- Grant/Contract Number:
- SC0006269; SC0006702
- OSTI ID:
- 1235101
- Alternate ID(s):
- OSTI ID: 1348403
- Journal Information:
- Proceedings of the National Academy of Sciences of the United States of America, Journal Name: Proceedings of the National Academy of Sciences of the United States of America Vol. 111 Journal Issue: 51; ISSN 0027-8424
- Publisher:
- Proceedings of the National Academy of SciencesCopyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
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