NOAA - Great Lakes Environmental Research Laboratory
January 2018 - Present
Ball, E.E., D.E. Smith, E.J. ANDERSON, and e. al. Water velocity modeling can delineate nearshore and main channel plankton environments in a large river. Hydrobiologia 815(1):125-140 (DOI:10.1007/s10750-018-3556-5) (2018).
Methods to distinguish nearshore and main channel ecosystems within large rivers are essential for observing physical, chemical, and biological features that influence overall river ecosystem function. Water velocity fields based on hydrodynamic modeling of water flow trajectory were used to evaluate water history (i.e., water moving slowly as in a slack water region, or more rapidly, as characteristic of the main channel) prior to passing a given point in the Upper St. Lawrence River. Using this method to differentiate zones in the river, observations of biotic and abiotic variables in nearshore and main channel zones during late spring and summer (June–August) were compared to assess the difference in these water column river ecosystems. Differences in plankton community composition between nearshore and main channel waters along the Upper St. Lawrence River were investigated to test the hypothesis that nearshore and main channel environments in large river systems have different biotic (e.g., phytoplankton, crustacean zooplankton, and rotifer concentrations) and abiotic [e.g., water temperature, specific conductivity, silicate, colored dissolved organic matter (CDOM), and total phosphorus] characteristics. Nearshore water had significantly higher concentrations of CDOM and chlorophyll-a than main channel waters. With distance downstream, crustacean zooplankton and rotifers decreased in abundance in both nearshore and main channel regions. This study describes an effective method for stratified sampling design that differentiates nearshore and main channel ecosystems in the water column of large rivers.
Biddanda, B.A., e. al, including, M.E. OGDAHL, Q. LIU, T.H. JOHENGEN, E.J. ANDERSON, and S.A. RUBERG. Chronicles of hypoxia: Time-series buoy observations reveal annually recurring seasonal basin-wide hypoxia in Muskegon Lake – A Great Lakes estuary. Journal of Great Lakes Research 44(2):219-229 (DOI:10.1016/j.jglr.2017.12.008) (2018). https://www.glerl.noaa.gov/pubs/fulltext/2018/20180004.pdf
We chronicled the seasonally recurring hypolimnetic hypoxia in Muskegon Lake – a Great Lakes estuary over 3 years, and examined its causes and consequences. Muskegon Lake is a mesotrophic drowned river mouth that drains Michigan's 2nd largest watershed into Lake Michigan. A buoy observatory tracked ecosystem changes in the Muskegon Lake Area of Concern (AOC), gathering vital time-series data on the lake's water quality from early summer through late fall from 2011 to 2013 (www.gvsu.edu/buoy). Observatory-based measurements of dissolved oxygen (DO) tracked the gradual development, intensification and breakdown of hypoxia (mild hypoxia <4 mg DO/L, and severe hypoxia <2 mg DO/L) below the ~6 m thermocline in the lake, occurring in synchrony with changes in temperature and phytoplankton biomass in the water column during July–October. Time-series data suggest that proximal causes of the observed seasonal hypolimnetic DO dynamics are stratified summer water-column, reduced wind-driven mixing, longer summer residence time, episodic intrusions of cold DO-rich nearshore Lake Michigan water, nutrient run off from watershed, and phytoplankton blooms. Additional basin-wide water-column profiling (2011–2012) and ship-based seasonal surveys (2003–2013) confirmed that bottom water hypoxia is an annually recurring lake-wide condition. Volumetric hypolimnetic oxygen demand was high (0.07–0.15 mg DO/Liter/day) and comparable to other temperate eutrophic lakes. Over 3 years of intense monitoring, ~9–24% of Muskegon Lake's volume experienced hypoxia for ~29–85 days/year – with the potential for hypolimnetic habitat degradation and sediment phosphorus release leading to further eutrophication. Thus, time-series observatories can provide penetrating insights into the inner workings of ecosystems and their external drivers.
Bunnell, D.B., e.a. including, E.S. RUTHERFORD, H.A. VANDERPLOEG, S.A. POTHOVEN, A.K. ELGIN, and M.D. ROWE. Are Changes in Lower Trophic Levels Limiting Prey-Fish Biomass and Production in Lake Michigan? Great Lakes Fishery Commission, (2018). http://www.glfc.org/pubs/misc/2018-01.pdf
Filstrup, C.T., T. Wagner, S.K. Oliver, C.A. STOW, K.E. Webster, E.H. Stanley, and J.A. Downing. Evidence for regional nitrogen stress on chlorophyll a in lakes across large landscape and climate gradients. Limnology and Oceanography 63(S1):S324-S339 (DOI:doi.org/10.1002/lno.10742) (2018). https://www.glerl.noaa.gov/pubs/fulltext/2017/20170036.pdf
Nitrogen (N) and phosphorus (P) commonly stimulate phytoplankton production in lakes, but recent observations from lakes from an agricultural region suggest that nitrate may have a subsidy-stress effect on chlorophyll a (Chl a). It is unclear, however, how generalizable this effect might be. Here, we analyzed a large water quality dataset of 2385 lakes spanning 60 regions across 17 states in the Northeastern and Midwestern U.S. to determine if N subsidy-stress effects on phytoplankton are common and to identify regional landscape characteristics promoting N stress effects in lakes. We used a Bayesian hierarchical modeling framework to test our hypothesis that Chl a–total N (TN) threshold relationships would be common across the central agricultural region of the U.S. (“the Corn Belt”), where lake N and P concentrations are high. Data aggregated across all regions indicated that high TN concentrations had a negative effect on Chl a in lakes with concurrent high total P. This large-scale pattern was driven by relationships within only a subset of regions, however. Eight regions were identified as having Chl a–TN threshold relationships, but only two of these regions located within the Corn Belt clearly demonstrated this subsidy-stress relationship. N stress effects were not consistent across other intense agricultural regions, as we hypothesized. These findings suggest that interactions among regional land use and land cover, climate, and hydrogeology may be important in determining the synergistic conditions leading to N subsidy-stress effects on lake phytoplankton
Glaspie, C.N., M. Clouse, A.T. Adamack, Y.K. Cha, S.A. Ludsin, D.M. MASON, M.R. Roman, C.A. STOW, and S.B. Brandt. Effect of hypoxia on diet of Atlantic bumper Chloroscombrus chrysurus in the northern Gulf of Mexico Transactions of the American Fisheries Society 147(4):740-748 (DOI:10.1002/tafs.10063) (2018). https://www.glerl.noaa.gov/pubs/fulltext/2018/20180007.pdf
Cultural eutrophication is a global problem that often leads to hypoxic conditions in coastal systems. While improving, our understanding of the impacts of hypoxia on trophic interactions in pelagic and bentho‐pelagic food webs is limited. Toward this end, we evaluated diet composition and mass‐specific consumption of Atlantic bumper Chloroscombrus chrysurus, a numerically dominant planktivorous fish in the northern Gulf of Mexico, relative to dissolved oxygen concentration and fish size. Atlantic bumper catch per unit effort (CPUE) was similar in hypoxic and normoxic areas. Mean mass‐specific consumption of small Atlantic bumper in hypoxic areas was greater than that of both small and large individuals in normoxic areas. The most commonly ingested prey type for both large and small Atlantic bumper was shrimp larvae. Large quantities of fish larvae were consumed by adult Atlantic bumper in hypoxic regions. These findings demonstrate that hypoxia can alter feeding of dominant fishes in the northern Gulf of Mexico, which may influence energy flow in the region.
GRONEWOLD, A.D., V. Fortin, R. Caldwell, and J. Noel. Resolving hydrometeorological data discontinuities along an international border. Bulletin of the American Meteorological Society 99(5):899-910 (DOI:10.1175/BAMS-D-16-0060.1) (2018). https://www.glerl.noaa.gov/pubs/fulltext/2018/20180008.pdf
Monitoring, understanding, and forecasting the hydrologic cycle of large freshwater basins often requires a broad suite of data and models. Many of these data sets and models, however, are susceptible to variations in monitoring infrastructure and data dissemination protocols when watershed, political, and jurisdictional boundaries do not align. Reconciling hydrometeorological monitoring gaps and inconsistencies across the international Laurentian Great Lakes - St. Lawrence River Basin is particularly challenging because of its size, and because the Basin’s dominant hydrologic feature is the vast surface waters of the Great Lakes. For tens of millions of Canadian and US residents that live 1 within the Great Lakes Basin, seamless binational data sets are needed to better understand and predict coastal water level fluctuations and other conditions that could potentially threaten human and environmental health. Binational products addressing this need have historically been developed and maintained by the Coordinating Committee on Great Lakes Basic Hydraulic and Hydrologic Data (Coordinating Committee). The Coordinating Committee recently held its 100th semiannual meeting and reflected on a range of historical accomplishments while setting goals for future work. This article provides a synthesis of those achievements and goals. Particularly significant legacy and recently-developed data sets of the Coordinating Committee include historical Great Lakes surface water elevations, basin-scale tributary inflow to the Great Lakes, and basin-scale estimates of both over-lake and over-land precipitation. Moving forward, members of the Coordinating Committee will work towards customizing state-of-the-art hydrologic and meteorological forecasting systems across the entire Great Lakes Basin, and to promoting their products and protocols as templates for successful binational coordination across other large binational freshwater basins.
HAWLEY, N., D. BELETSKY, and J. WANG. Ice thickness measurements in Lake Erie during the winter of 2010–2011. Journal of Great Lakes Research 44(3):388-397 (DOI:10.1016/j.jglr.2018.04.004) (2018).
Time series measurements of ice thicknesses were made at either 1 or 2 Hz at 6 locations in the western part of Lake Erie's central basin during the winter of 2010–2011. Ice was observed over approximately 80 days beginning in late December and continuing through mid-March. Deformation and ridging of ice occurred frequently and produced ice thicknesses of up to 10 m, and over 6 m at all stations. The measurements show considerable variability (up to several meters) between stations, even when the distance between them is <500 m. Comparison of the measurements to those generated by the National Ice Center show good agreement for undeformed thicknesses, but the Ice Center analyses do not account for increased thicknesses due to ice ridging. Several different measures of ice thickness (based on different averaging times and the parameter used to characterize the resulting distribution of thicknesses) are used to characterize the data, and the results can vary widely depending upon which measure is used. The best measure to use will depend upon the use for which the data is intended.
Kelley, J.G.W., Y. Chen, E.J. ANDERSON, G.A. LANG, and J. Xu. Upgrade of NOS Lake Erie Operational Forecast System (LEOFS) to FVCOM: Model Development and Hindcast Skill Assessment. NOAA Technical Memorandum NOS CS 40 NOAA Office of Coast Survey, Silver Spring, MD, 92 pp. (2018).
No abstract.
Kolker, A.S., A.M. Dausman, M.A. Allison, G.L. Brown, P. CHU, K. de Mutsert, C.E. Fitzpatrick, J.R. Henkel, D. Justic, B.A. Kleiss, E. McCoy, E. Meselhe, and C.P. Richards. Rethinking the RIver. EOS, Earth & Space News (DOI:10.1029/2018EO101169) (2018). https://eos.org/features/rethinking-the-river
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Lei, R., B. Cheng, P. Heil, T. Vhima, J. WANG, Q. Ji, and Z. Zhang. Seasonal and Interannual Variations of Sea Ice Mass Balance From the Central Arctic to the Greenland Sea. Journal of Geophysical Research: Oceans 123(4):2422-2439 (DOI:10.1002/2017JC013548) (2018). https://www.glerl.noaa.gov/pubs/fulltext/2018/20180005.pdf
The seasonal evolution of sea ice mass balance between the Central Arctic and Fram Strait, as well as the underlying driving forces, remain largely unknown because of a lack of observations. In this study, two and three buoys were deployed in the Central Arctic during the summers of 2010 and 2012, respectively. It was established that basal ice growth commenced between mid‐October and early December. Annual basal ice growth, ranging from 0.21 to 1.14 m, was determined mainly by initial ice thickness, air temperature, and oceanic heat flux during winter. An analytic thermodynamic model indicated that climate warming reduces the winter growth rate of thin ice more than for thick ice because of the weak thermal inertia of the former. Oceanic heat flux during the freezing season was 2–4 W m−2, which accounted for 18–31% of the basal ice energy balance. We identified two mechanisms that modified the oceanic heat flux, i.e., solar energy absorbed by the upper ocean during summer, and interaction with warm waters south of Fram Strait; the latter resulted in basal ice melt, even in winter. In summer 2010, ice loss in the Central Arctic was considerable, which led to increased oceanic heat flux into winter and delayed ice growth. The Transpolar Drift Stream was relatively weak in summer 2013. This reduced sea ice advection out of the Arctic Ocean, and it restrained ice melt because of the cool atmospheric conditions, weakened albedo feedback, and relatively small oceanic heat flux in the north.
Linares, A., C.H. Wu, E.J. ANDERSON, and P.Y. CHU. Role of Meteorologically Induced Water Level Oscillations on Bottom Shear Stress in Freshwater Estuaries in the Great Lakes. Journal of Geophysical Research: Oceans 123(7):4970-4987 (DOI:10.1029/2017JC013741) (2018). https://www.glerl.noaa.gov/pubs/fulltext/2018/20180014.pdf
The role of meteorologically induced water level oscillations (MIWLOs) on bottom shear stresses in a freshwater estuary in the Great Lakes is investigated. Atmospheric data including air pressure, wind speed and direction, and radar reflectivity are compiled, and comprehensive field measurements including velocity profiles, water levels, river discharges, and bottom sediment properties in the Manistique River (MR) estuary, Michigan, are conducted. Wavelet and cross‐wavelet analysis reveals that large velocity events (>0.5 m/s) in the MR estuary are generated by high‐frequency MIWLOs (i.e., meteotsunamis and high‐frequency seiches) induced by energetic oscillations in air pressure and/or wind speed and direction with periods below 2 hr. Measured velocity profiles reveal that MIWLO‐dominated conditions can increase bottom shear stress by an order of magnitude in comparison with river‐dominated flow conditions. The hydrodynamic model indicates that bottom shear stresses under both the downstream and upstream flows during the MIWLO‐dominated event were significantly larger than those during river‐dominated conditions. The interactions of MIWLOs and flood flows can significantly alter the bottom shear stresses in the main river channel, and MIWLOs are revealed to be the principal resuspension mechanism in areas such as the upstream tributary branches where flood flows individually do not cause resuspension. Furthermore, the role of MIWLOs asymmetry in fresh water Great Lakes estuaries on velocity residuals and net sediment transport is revealed and discussed. Overall, this paper fills important knowledge gaps in the role of MIWLOs on sediment transport in enclosed basin estuaries, thus providing essential information for coastal management and estuarine remediation.
Liu, Q., E.J. ANDERSON, Y. Zhang, A.D. Weinke, K.L. Knapp, and B.A. Biddanda. Modeling reveals the role of coastal upwelling and hydrologic inputs on biologically distinct water exchanges in a Great Lakes estuary. Estuarine, Coastal and Shelf Science 209:41-55 (DOI:10.1016/j.ecss.2018.05.014) (2018).
Freshwater estuaries everywhere are under stress from anthropogenic activities and climate change. Muskegon Lake Estuary (MLE) is a freshwater estuary along the eastern shore of Lake Michigan characterized by algal blooms and hypoxia during the summer and designated as an Area of Concern (AOC) by the EPA. We developed a 3-D hydrodynamic model using the Semi-implicit Cross-scale Hydroscience Integrated System Model (SCHISM) to study the hydrodynamics of MLE with a focus on the cold-water intrusions from Lake Michigan into MLE. Substantial water exchange process was validated by comparisons with observations in the near-shore region of Lake Michigan and in the navigation channel between Lake Michigan and MLE. The model found that the cold-water intrusions from Lake Michigan to MLE occur during summer stratification, amounting to as much as 10% of MLE's total volume during one single episodic event. The intrusion was accompanied by a stronger surface outflow in the opposite direction, which may accelerate the delivery of MLE water to Lake Michigan. Through process-oriented model experiments, we examined the cold-water intrusion's responses to hydrological shift under climate change, and found that the increase in riverine input during upwelling weakens the intrusion. In addition, an increase of navigation channel width strengthens the cold-water intrusion, and that intrusion strength as well as intrusion period was directly related to wind speed. Our observation-modeling based findings would provide a good reference for the future study of biophysical interactions between coastal ocean and estuaries.
Nalepa, T.F., C.M. Riseng, A.K. ELGIN, and G.A. LANG. Abundance and Distribution of Benthic Macroinvertebrates in the Lake Huron System: Saginaw Bay, 2006-2009, and Lake Huron, including Georgian Bay and North Channel, 2007 and 2012. NOAA Technical Memorandum GLERL-172. NOAA, Great Lakes Environmental Research Laboratory, Ann Arbor, MI, 54 pp. (DOI:10.25923/aqe2-ma69) (2018). https://www.glerl.noaa.gov/pubs/tech_reports/glerl-172/tm-172.pdf
no abstract
Niu, Q., M. Xia, S.A. Ludsin, P.Y. CHU, D.M. MASON, and E.S. RUTHERFORD. High‐turbidity events in Western Lake Erie during ice‐free cycles: Contributions of river‐loaded vs. resuspended sediments. Limnology and Oceanography (DOI:10.1002/lno.10959) (2018). https://www.glerl.noaa.gov/pubs/fulltext/2018/20180018.pdf (IN PRESS)
High‐turbidity events (HTEs) are common phenomena in shallow‐water environments that can alter ecological interactions. The relative contributions of river input (external loading) vs. resuspension (internal loading) to the occurrence, duration, and influenced areas of HTEs are not fully understood in most systems, owing to the lack of long‐term, source‐specified sediment maps. Using a Finite Volume Community Ocean Model‐based wave‐current forced sediment model, we investigated sediment dynamics in the shallow, river‐dominated Western Lake Erie during ice‐free cycles (April–November) of 2002–2012. Results indicated that wind waves predominated sediment dynamics in the offshore areas, with river discharges causing substantial inshore to offshore gradients. Owing to varying wind waves and river discharges, both the mean and extreme sediment dynamics had distinctive seasonal variations. The basin was turbid during spring and fall, with frequent (> 15%), broad (O [102–103 km2]), and more persistent (means of 3.2/4.4 d during spring/fall) HTEs caused mainly by resuspension events. During summer, the basin was clearer with occasional (< 1%), small (O [1–102 km2]), and short (mean of 1.5 d) HTEs near the mouths generated by pulsing river loadings. Although river loading rarely induced basin‐wide HTEs, they were important during floods, enlarging the high‐turbidity areas by 11.3%. Overall, by delineating the drivers of HTEs in Western Lake Erie, this study furthered the understanding of sediment dynamics in shallow ecosystems and provides a basis for investigating the ecological impact of sediments from different sources in river‐ and wave‐energetic systems.
POTHOVEN, S.A. Seasonal feeding ecology of co-existing native and invasive benthic fish along a nearshore to offshore gradient in Lake Michigan. Environmental Biology of Fishes 101(7):1161-1174 (DOI:10.1007/s10641-018-0766-7) (2018). https://www.glerl.noaa.gov/pubs/fulltext/2018/20180006.pdf
Relative abundance, diet composition and feeding strategy were determined for three benthic fish, the native deepwater sculpin Myoxocephalus thompsonii (Girard, 1851) and slimy sculpin Cottus cognatus (Richardson, 1836), and the invasive round goby Neogobius melanostomus (Pallas, 1814), along a nearshore to offshore gradient in southeastern Lake Michigan during March–December 2010, 2015, and 2016. Round goby were most abundant in the nearshore (<25 m), slimy sculpin were most abundant in the transitional zone (35–65 m), and deepwater sculpin were most abundant in the offshore zone (>75 m). Despite a large degree of spatial separation, some species did overlap, with slimy and deepwater sculpin occurring in sympatry throughout the year in the offshore and transitional zones, and round goby overlapping with both sculpin species seasonally in the transitional zone. Deepwater sculpin exhibited specialization on Mysis diluviana in all depth regions. Slimy sculpin in the offshore reduced diet overlap with deepwater sculpin by specializing on fish eggs during spring and fall, whereas in the transitional depth zone, there was considerable overlap between sculpin species due to the high importance of Mysis in diets. The invasive round goby had a mixed diet, with some diet overlap with native sculpin, especially slimy sculpin, in the transitional zone. In the nearshore zone, round goby displayed a generalized diet with many prey contributing to the diet, but the average contribution of any prey was generally low. Spatial separation and variable feeding strategies help reduce, but not eliminate shared resource use amongst these benthic fish in Lake Michigan.
Pullen, J., R. Allard, H. Seo, A.J. Miller, S. Chen, P. Pezzi, T. Smith, P. CHU, J. Alves, and R. Caldeira. Coupled ocean-atmosphere forecasting at short and medium time scales In The Science of Ocean Prediction, The Sea. P. Lermusiaux and K. Brink N. Pinardi. (2018).
Recent technological advances over the past few decades have enabled the development of fully coupled atmosphere-ocean modeling prediction systems which are used today to support short-term (days to weeks) and medium-term (10-21 days) needs for both the operational and research communities. Utilizing several coupled modeling systems we overview the coupling framework, including model components and grid resolution considerations, as well as the coupling physics by examining heat fluxes between atmosphere and ocean, momentum transfer, and freshwater fluxes. These modeling systems can be run as fully coupled atmosphere-ocean and atmosphere-ocean-wave configurations. Examples of several modeling systems applied to complex coastal regions including Madeira Island, Adriatic Sea, Coastal California, Gulf of Mexico, Brazil, and the Maritime Continent are presented. In many of these studies, a variety of field campaigns have contributed to a better understanding of the underlying physics associated with the atmosphere-ocean feedbacks. Examples of improvements in predictive skill when run in coupled mode versus standalone are shown. Coupled model challenges such as model initialization, data assimilation, and earth system prediction are discussed.
Riseng, C.M., K. Whehrly, L. Wang, E.S. RUTHERFORD, J.E. McKenna, L.B. Johnson, L.A. Mason, C. Casttiglione, T. Hollenhorst, and B. Sparks-Jackson. Ecosystem classification and mapping of the Laurentian Great Lakes. Canadian Journal of Fisheries and Aquatic Sciences (DOI:10.1139/cjfas-2017-0242) (2018). https://www.glerl.noaa.gov/pubs/fulltext/2018/20180012.pdf (IN PRESS)
Owing to the enormity and complexity of the Laurentian Great Lakes, an ecosystem classification is needed to better understand, protect, and manage this largest freshwater ecosystem in the world. Using a combination of statistical analyses, published knowledge, and expert opinion, we identified key driving variables and their ecologically relevant thresholds and delineated and mapped aquatic systems for the entire Great Lakes. We identified and mapped 77 aquatic ecological units (AEUs) that depict unique combinations of depth, thermal regime, hydraulic, and landscape classifiers. Those 77 AEU types were distributed across 1997 polygons (patches) ranging from 1 to >48 000 km2 in area and were most diverse in the nearshore (35 types), followed by the coastal margin (26), and then the offshore (16). Our classification and mapping of ecological units captures gradients that characterize types of aquatic systems in the Great Lakes and provides a geospatial accounting framework for resource inventory, status and trend assessment; research for ecosystem questions; and management and policy-making.
Spear, M.J., A.K. ELGIN, and E.K. Grey. Current and Projected Distribution of the Red-Eared Slider Turtle, Trachemys scripta elegans, in the Great Lakes Basin. The American Midland Naturalist 179(2):191-221 (DOI:10.1674/0003-0031-179.2.191) (2018). https://www.glerl.noaa.gov/pubs/fulltext/2018/20180009.pdf
Exotic species introduced through the pet trade pose an ecological and economic threat to the Great Lakes region. Trachemys scripta elegans, the red-eared slider turtle, is a globally invasive species already present in the Great Lakes basin whose distribution and potential for spread is poorly known. We assembled a detailed dataset on T. s. elegans occurrence and establishment in the region and created a niche model to assess the potential for the spread of this species under current climate conditions and future scenarios. We found T. s. elegans occurs throughout the Great Lakes basin and suitable area will likely increase from 26% to 39–50% of the entire basin by 2050, with Lake Erie at greatest risk with ∼95% of its total area suitable for T. s. elegans by 2050. These findings highlight the need for further research to assess impacts of T. s. elegans on native species and proactive efforts to prevent its further spread.
STOW, C.A., K.E. Webster, T. Wagner, N.R. Lottig, P.A. Soranno, and Y.K. Cha. Small values in big data: The continuing need for appropriate metadata. Ecological Informatics 45:26-30 (DOI:10.1016/j.ecoinf.2018.03.002) (2018). https://www.glerl.noaa.gov/pubs/fulltext/2018/20180002.pdf
Compiling data from disparate sources to address pressing ecological issues is increasingly common. Many ecological datasets contain left-censored data – observations below an analytical detection limit. Studies from single and typically small datasets show that common approaches for handling censored data — e.g., deletion or substituting fixed values — result in systematic biases. However, no studies have explored the degree to which the documentation and presence of censored data influence outcomes from large, multi-sourced datasets. We describe left-censored data in a lake water quality database assembled from 74 sources and illustrate the challenges of dealing with small values in big data, including detection limits that are absent, range widely, and show trends over time. We show that substitutions of censored data can also bias analyses using ‘big data’ datasets, that censored data can be effectively handled with modern quantitative approaches, but that such approaches rely on accurate metadata that describe treatment of censored data from each source.
Sundstrom, S.M., D.G. Angeler, C. Barichievy, T. Eason, A.S. Garmestani, L. Gunderson, M. Knutson, K.L. Nash, T. Spanbauer, C.A. STOW, and C.R. Allen. The distribution and role of functional abundance in cross‐scale resilience. Ecological Society of America (DOI:10.1002/ecy.2508) (2018). https://www.glerl.noaa.gov/pubs/fulltext/2018/20180016.pdf (IN PRESS)
The cross‐scale resilience model suggests that system level ecological resilience emerges from the distribution of species’ functions within and across the spatial and temporal scales of a system. It has provided a quantitative method for calculating the resilience of a given system, and so has been a valuable contribution to a largely qualitative field. As it is currently laid out, the model accounts for the spatial and temporal scales at which environmental resources and species are present and the functional roles species play, but does not inform us about how much resource is present, or how much function is provided. In short, it does not account for abundance in the distribution of species and their functional roles within and across the scales of a system. We detail the ways in which we would expect species’ abundance to be relevant to the cross‐scale resilience model based on the extensive abundance literature in ecology. We also put forward a series of testable hypotheses that would improve our ability to anticipate and quantify how resilience is generated, and how ecosystems will (or will not) buffer recent rapid global changes. This stream of research may provide an improved foundation for the quantitative evaluation of ecological resilience.
WANG, J., J. KESSLER, X. BAI, A.H. CLITES, B.M. LOFGREN, A. Assuncao, J.F. Bratton, P. CHU, and G.A. LESHKEVICH. Decadal variability of Great Lakes ice cover in response to AMO and PDO, 1963-2017. Journal of Climate 31(18):7249-7268 (DOI:10.1175/JCLI-D-17-0283.1) (2018). https://www.glerl.noaa.gov/pubs/fulltext/2018/20180013.pdf
In this study, decadal variability of ice cover in the Great Lakes is investigated using historical airborne and satellite measurements from 1963 to 2017. It was found that Great Lakes ice cover has 1) a linear relationship with the Atlantic multidecadal oscillation (AMO), similar to the relationship of lake ice cover with the North Atlantic Oscillation (NAO), but with stronger impact than NAO; 2) a quadratic relationship with the Pacific decadal oscillation (PDO), which is similar to the relationship of lake ice cover to Niño-3.4, but with opposite curvature; and 3) decadal variability with a positive (warming) trend in AMO contributes to the decreasing trend in lake ice cover. Composite analyses show that during the positive (negative) phase of AMO, the Great Lakes experience a warm (cold) anomaly in surface air temperature (SAT) and lake surface temperature (LST), leading to less (more) ice cover. During the positive (negative) phase of PDO, the Great Lakes experience a cold (warm) anomaly in SAT and LST, leading to more (less) ice cover. Based on these statistical relationships, the original multiple variable regression model established using the indices of NAO and Niño-3.4 only was improved by adding both AMO and PDO, as well as their interference (interacting or competing) mechanism. With the AMO and PDO added, the correlation between the model and observation increases to 0.69, compared to 0.48 using NAO and Niño-3.4 only. When November lake surface temperature was further added to the regression model, the prediction skill of the coming winter ice cover increased even more.
XIAO, C., B.M. LOFGREN, and J. WANG. WRF-based assessment of the Great Lakes' impact on cold season synoptic cyclones. Atmospheric Research 214:189-203 (DOI:10.1016/j.atmosres.2018.07.020) (2018).
Synoptic events in December are studied with regard to the Great Lakes' influence on extratropical cyclones using the Weather Research and Forecasting (WRF) model. Here, four selected events are arranged into two pairs of comparisons: strong events (2006, 2009) versus weak events (2008, 2013); traversing events (2008, 2009) versus bypassing events (2006, 2013). For each case, the land surface model in WRF is initialized with two different configurations: the control run with real land coverage and the no-lake run in which the lakes are replaced by land. The control simulation shows that the WRF model exhibits a good performance in reproducing precipitation, sea-level pressure and air temperature. Comparisons between control and no-lake runs among these cases indicate that the lake-air temperature gradient, inducing vertical heat flux, is most prominent in the weak bypassing event (case 2013), while lake-land roughness contrast contributes to the low-level moisture convergence. The Great Lakes' impact generally strengthens the cyclonic system near the surface but is sensitive to the background flow. This effect becomes much more significant for the development of cyclones with colder atmospheric conditions, suggesting that the meso-to-synoptic scale interaction should be taken into account when considering the Great Lakes' influence.
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