Synthesis of Tree-Ring Records and Coupled Climate Model Simulations to Understand North Atlantic Hydroclimate Responses to Volcanic Eruptions in the Last Millennium
Abstract
Hydroclimate in northeastern North America is influenced by a combination of North Atlantic modes of climate variability such as Atlantic Multidecadal Variability (AMV), North Atlantic Oscillation (NAO), and Atlantic Meridional Overturning Circulation (AMOC). By combining an ensemble of state-of-the-art fully coupled climate model simulations with a newly developed tree-ring network across Labrador in Canada, we assess the relative role of different drivers of regional hydroclimate over the last millennium. We identified extreme dry years in Labrador in the model simulations and tree-ring records and found some to occur after volcanic eruptions.
We therefore focus on the role of volcanic forcing in affecting precipitation across the broader extratropical North Atlantic region through changes in sea surface temperature (SST) and sea level pressure (SLP) patterns, AMOC strength, and atmospheric moisture advection, through all transient forcing and volcanic-only forcing ensemble members from the Community Earth System Model Last Millennium Ensemble from 850 to 2000 C.E. Lowered North Atlantic SST are found during extreme dry Labrador years; consistent colder SST are also seen following the top 10% biggest volcanic eruptions, due to lowered incident solar radiation. Winter SLP anomalies resembled the NAO with a strong north-south dipole structure during extreme dry years; however, a strong east-west SLP dipole structure was identified after volcanic eruptions, reminiscent of the East Atlantic pattern (EAP). This raises the question of the relative contributions of NAO and EAP in response to volcanic forcing to regional hydroclimate and their interaction with North Atlantic SST associated with AMV.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.A51H2258W
- Keywords:
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- 3305 Climate change and variability;
- ATMOSPHERIC PROCESSESDE: 3337 Global climate models;
- ATMOSPHERIC PROCESSESDE: 3339 Ocean/atmosphere interactions;
- ATMOSPHERIC PROCESSESDE: 4504 Air/sea interactions;
- OCEANOGRAPHY: PHYSICAL