1. Glacial Inception in Northeast Canada: The Role of Insolation, Meteorology, and Topography
Leah Birch Timothy Cronin, and Eli Tziperman
Earth and Planetary Sciences, Harvard University; Earth, Atmosphere, and Planetary Sciences, MIT
Introduction
Since the Middle Pleistocene, Earth’s climate has cycled between ice ages and interglacials, like our current climate. Geologic evidence suggests that the last glacial inception 115 kya occurred within the mountains of Baffin Island. Currently, state-of-the-art global climate models (GCMs) have difficulty simulating the inception of large ice sheets from an interglacial, likely related to their coarse spatial resolution, which lowers topography and requires the use of uncertain cloud parameterizations.
We approach the glacial inception problem by testing the sensitivity of mountain glaciers to insolation, meteorology, and topography using a regional cloud resolving configuration of Weather Research and Forecasting Model (WRF).
Resulting Snow Depth on the Penny Ice Cap
Note that GCM Topography causes 1000kg/m2 snow loss per year.
VI. GCM Topography Changes precipitation pattern and amount
IV. Implications for Ice Sheet Flow
Without an ice sheet model, we parameterize downslope flow by sorting the Penny Ice Cap by elevation. We integrate the mass balance downslope to determine the equilibrium ice cap edge.
II. WRF Set-Up
12 km Parent Domain
4 km Nested Domain
Present Day Land Type
over Baffin Island.
Insolation (Present day, Min., &Max)
Summer Temperature (Avg, Cold, Warm)
Topography (Realistic, GCM)
Penny Ice Cap
VII. Summary/Conclusions
We use a 4km WRF configuration to address two main issues GCMs may have with glacial inception: (1) poor horizontal resolution, leading to low topography over Baffin Island and (2) their use of convective and cloud parameterizations.
Findings:
We did not get snow growth into unglaciated regions, as this is likely the result of ice sheet flow.
Cold summers and wet meteorology have the most ice cap growth and the mass balance integration implies an expansion of the Penny Ice Cap.
Realistic topography increases accumulation and decreases melting but makes the cloud forcing less negative.
V. What is the cloud effect in this region?
We bin the domain by height percentages again to determine a trend between elevation and cloud radiative forcing.