SEAICE

It has recently been forecasted that Arctic summer sea ice may completely disappear sometime during this century. Sea ice is an indicator of and has an influence on the rest of the climate system. It has a strong, direct and well-documented effect on Arctic albedo and sea surface temperature, and enhances evaporation and the Arctic hydrologic cycle. The sea ice-evaporation/precipitation link is a fundamental component of climate dynamics, and has been cited as an essential element of global warming, abrupt climate change, Dansgaard-Oeschger events, the Pleistocene ice ages, and “snowball earth”. However, there are remarkably few measurements that quantify the fundamental link between the ice-free Arctic Ocean area and evaporation/precipitation. The objective of this project was to quantify how moisture evaporated from the Arctic Ocean and surrounding seas contributes to precipitation in the Arctic regions, and how such moisture supply is controlled by sea ice extent. We do this by studying oxygen and hydrogen isotopic compositions in precipitation collected storm-by-storm at two Arctic stations, Barrow and Atqasuk, Alaska.

Precipitation samples for each storm that brings about 2 mm water of rain (or 2 cm of snow) are collected in at the ARM Climate Research Facility (ACRF) at Barrow and Atqasuk, Alaska, respectively. The difference between the two sites will be interesting because for a given storm costal and inland sites often have different a moisture mix from subtropical versus local sources. The reason for sampling each storm is because storm tracks have significant variations, and so do sea ice distributions. By looking at the weather patterns and its evolution that are responsible to a given storm, we will be able to determine what part of the ocean surface contributes to the moisture budget of the storm. Samples will be analyzed by for D/H and 18O/16O ratios at the Dartmouth’s Stable Isotope Geochemistry Laboratory. The results will be interpreted for the individual influences of the ice-free area of the Arctic, of storm tracks, of atmospheric temperatures at both moisture sources and precipitation sites, and of circulation changes associated with the Arctic Oscillation and/or the North Atlantic Oscillation. This project intends to yield a quantitative understanding of the link between sea ice and moisture sources of Arctic precipitation, which is important in the study of climate dynamics on a wide range of time scales. It will also provide new data and insight for interpretations of climate information recorded in ice cores, which is relevant for testing global warming projections, abrupt global change scenarios, and ice age theories, as well as for further verification of climate models.

Timeline