Hallet Lake (61.49N, 146.24W) is located near the crest of Chugach Range in south-central Alaska, at 1128 m asl. The relatively small (0.6 km2), deep (zmax = 41m) lake is fed by seven cirque glaciers in the watershed. The lake is about 50 km north of a long-term weather station in Valdez, well-situated to evaluate the relations between sediment proxy data (including biogenic silica and organic-matter content). The well-preserved neoglacial moraines above the lake also provide information about past climate, and compliment the sedimentary record. Hallet Lake, along with nearby Greyling Lake are being studied as part of the ARCSS 2 kyr Project.
Three cores were recovered from Hallet Lake, core HT01 was used for primary analysis. Nine radiocarbon ages were used to develop and age-depth model (below, left). Biogenic-silica was measured at a 1-cm-interval (decadal resolution) for the top 2m (2 kyr) of the core, and is well-related to Valdez summer temperature (r = 0.86). This relationship was used to develop a transfer function, and a BSi-inferred summer temperature record for the past 2 kyr (below, center). Organic matter was analyzed at a 2.5-cm-interval, and shows strong similarities to OM at Greyling Lake and may be related to Aleutian Low strength over the past several thousand years (below, right).
Modern and past glacier extents (as indicated by the prominent neoglacial moraines in the glacier forefields) above Hallet Lake were mapped in July 2006, and lichenometry was used to provide a chronology of past glacier advances (below, left). The area-altitude method was used to calculate equilibrium line altitudes for 9 cirque glaciers near Hallet Lake, and for their Little Ice Age extents (as indicated by the largest neoglacial moraine for the cirques)(below, right).
Two water temperature loggers have been deployed since July 2006. Air and water temperature have been measured at Greyling Lake since 2004, and is available here. Greyling Lake is 30 km east of Hallet Lake, and at similar elevation, so they probably experience similar climates. One mooring was deployed in 2006 and the water temperature data are available here.
McKay, N. P., Kaufman, D.S., and Michelutti, N., submitted, Biogenic-silica concentration as a high-resolution, quantitative temperature proxy at Hallet Lake, south-central Alaska. Geophyscial Research Letters.