Impacts of Sensible Heat from Precipitation on Ice Cover in Large Lakes
Abstract
Sensible heat of precipitation (Hsp) to lakes, oceans, and ice cover has been often overlooked yet can play a significant role in the energy budget. However, it is often neglected or lies buried in complex model systems. In the North American Great Lakes (hereafter Great Lakes), the world largest freshwater system, quantification of Hsp impacts on its water temperature and ice cover is relatively important among many other detail processes in numerical models because 1. fall-winter precipitation around the region has increased over the past decades; 2. the temperature gradient between the water surface and the wet-bulb temperature of the air above, which is approximately the temperature of rain droplets, can be large in these seasons; and 3. the increasing precipitation along with the large air-water temperature gradient may have resulted in notable contribution of Hsp to the changes in lake heat content and ice cover. This study evaluates the impacts of Hsp to water temperature and ice cover on the Great Lakes. First, Hsp is estimated using U.S. - Canadian observational precipitation dataset, surface meteorology, and satellite-based water surface temperature. Second, we evaluate the impacts of Hsp on the ice cover using three-dimensional coupled ice-hydrodynamic model based on the unstructured grid Finite-Volume Community Ocean Model (FVCOM). The estimated daily Hsp for the recent cold seasons (October 2016-May 2017, October 2017- May 2018) ranges from -16 W/m2 (cooling of water surface) to 4 W/m2 to the water, and from -2 W/m2 to 6 W/m2 to the ice. The estimated cooling of water due to Hsp is relatively significant to the fall preconditioning for the ice development in the following winter, as the lowest value is equivalent to cooling of the top 1-m water surface by 0.33 oC per day. On the other hand, the direct heat input to the ice due to Hsp is relatively small. The presentation will further show the results of a longer-term evaluation of Hsp, as well as the results of sensitivity experiments with FVCOM and how the Great Lakes water temperature and ice cover have been affected by Hsp.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.A21L2887F
- Keywords:
-
- 3305 Climate change and variability;
- ATMOSPHERIC PROCESSESDE: 3355 Regional modeling;
- ATMOSPHERIC PROCESSESDE: 1622 Earth system modeling;
- GLOBAL CHANGEDE: 1637 Regional climate change;
- GLOBAL CHANGE