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Depth profiles of water column chemical and physical properties were assessed with seasonal-scale frequency from four lakes in the Itasca State Park from 2006-2009 and from 2019-2023. The data was used to assess the mixing status and major geochemical constituents within the lakes. Several parameters were routinely measured with deployable probes at meter or sub-meter resolution at the deepest location in each lake. Water samples were also collected for laboratory analysis. Bathymetry data collected in 2022 is supplied as rasters.
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Lake and drained lake basin systems in lowland permafrost regions
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Sedimentary plant wax δ 2H values are common proxies for hydrology, a poorly constrained variable in the Arctic. However, it can be difficult to distinguish plant waxes derived from aquatic versus terrestrial plants, causing uncertainty in climate interpretations. We test the hypothesis that Arctic lake sediment mid- and long-chain plant waxes derive from aquatic and terrestrial plants, respectively. We compare n-alkanoic acid and n-alkane chain-length distributions and n-alkanoic acid δ2H and δ13C values of the 29 most abundant modern plant taxa to those for soils, water filtrates, and lake sediments in the Qaupat Lake (QPT) catchment, Nunavut, Canada. Chain length distributions are variable among terrestrial plants, but similar and dominated by mid-chain waxes among submerged/floating aquatic plants. Sedimentary wax distributions are similar to those in submerged/floating aquatic plants and to Salix spp., which are among the most abundant terrestrial plants in the QPT catchment. Mid-chain n-alkanoic acid δ2H values are similar in sediments and submerged/ floating aquatic plants, but 50‰ lower than Salix spp. In contrast, sedimentary long-chain n-alkanoic acid δ2H values fall between those for submerged/floating aquatic plants and Salix spp. We therefore infer that mid-chain waxes in QPT are primarily from aquatic plants, whereas long-chain waxes are from a mix of terrestrial and aquatic plants. In Arctic lakes like QPT, terrestrial wax transport via leaf litter and surface flow is limited by low-lying topography and sparse vegetation. If these lakes also have abundant aquatic plants growing near the sediment-water interface, the aquatic plants can contribute large portions of sedimentary waxes.more » « less
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Abstract Lake-effect precipitation is convective precipitation produced by relatively cold air passing over large and relatively warm bodies of water. This phenomenon most often occurs in North America over the southern and eastern shores of the Great Lakes, where high annual snowfalls and high-impact snowstorms frequently occur under prevailing west and northwest flow. Locally higher snow or rainfall amounts also occur due to lake-enhanced synoptic precipitation when conditionally unstable or neutrally stratified air is present in the lower troposphere. While likely less common, lake-effect and lake-enhanced precipitation can also occur with easterly winds, impacting the western shores of the Great Lakes. This study describes a 15-year climatology of easterly lake-effect (ELEfP) and lake-enhanced (ELEnP) precipitation (conjointly Easterly Lake Collective Precipitation: ELCP) events that developed in east-to-east-northeasterly flow over western Lake Superior from 2003 to 2018. ELCP occurs infrequently but often enough to have a notable climatological impact over western Lake Superior with an average of 14.6 events per year. The morphology favors both single shore-parallel ELEfP bands due to the convex western shoreline of Lake Superior and mixed-type banding due to ELEnP events occurring in association with “overrunning” synoptic-scale precipitation. ELEfP often occurs in association with a surface anticyclone to the north of Lake Superior. ELEnP typically features a similar northerly-displaced anticyclone and a surface cyclone located over the U.S. Upper Midwest that favor easterly boundary-layer winds over western Lake Superior.more » « less
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Synoptic Conditions and Lake-to-Lake Connections for Days with Lake Effect on All of the Great LakesAbstract An investigation of lake effect (LE) and the associated synoptic environment is presented for days when all five lakes in the Great Lakes (GL) region had LE bands [five-lake days (5LDs)]. The study utilized an expanded database of observed LE clouds over the GL during 25 cold seasons (October–March) from 1997/98 to 2021/22. LE bands occurred on 2870 days (64% of all cold-season days). Nearly a third of all LE bands occurred during 5LDs, although 5LDs consisted of just 17.1% of LE days. A majority of 5LDs (56.5%) had lake-to-lake (L2L) bands, and these days comprised 43.5% of all L2L occurrences. 5LDs occurred with a mean of 26.1 (SD = 6.2) days per cold season until 2008/09 and then decreased to a mean of 13.8 (SD = 5.5) days during subsequent cold seasons. January and February had the largest number of consecutive LE days in the GL with a mean of 5.7 and 5.4 days, respectively. As the number of consecutive LE days increases, both the number of 5LDs and the occurrence of consecutive 5LD increase. This translates to an increased potential of heavy snowfall impacts in multiple, localized areas of the GL for extended time periods. The mean composite synoptic pattern of 5LDs exhibited characteristics consistent with lake-aggregate disturbances and showed similarity to synoptic patterns favorable for LE over one or two of the GL found by previous studies. The results demonstrate that several additional areas of the GL are often experiencing LE bands when a localized area has active LE bands occurring.more » « less
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1038/s43017-021-00238-9
