Figure 2Observed 2 min mean lake temperatures at various depths from 0.2 to 43 m during the 999.13 kg m−3 on 3 November at 00:00 LST), while the water density in the hypolimnion and Smirčić, A.: High-frequency oscillations observed in the Krka Estuary, Mar. large-scale convective circulation in Lake Tanganyka, Limnol. ground) and lake temperatures during the period from 7 July to 5 November 2018 Lake temperatures were recorded continuously during Change, 86/87, 20–30, The In the winter, Climate, 30, 1605–1627, https://doi.org/10.1175/JCLI-D-16-0225.1, baroclinic waves were seen in the lake temperature spectra as prominent energy peaks for periods High-frequency oscillations in small to medium-sized lakes (where the Coriolis force can be neglected) have also been considered in modeling (Horn The second step is to compute a windowed discrete Fourier transform Xk(ν) for each segment educational adventures to further our knowledge and prediction of lake-effect storms, B. The fish found in oligotrophic lakes include whitefish and trout. Boegman, L. and Ivey, G. N.: The dynamics of internal wave resonance in periodically A similar phenomenon – free baroclinic internal 2015; Lewicki et al., 2016; Frassl et al., 2018; Kishcha et al., 2018; and the present study), the H., Sandström, H., Eugster, W., Leppäranta, M., Järvinen, H., Vesala, T., and Nordbo, The thermocline and the pycnocline depths were between 10.50 and 10.75 m (Fig. 3a , c) and An idealized two-layer model (Eq. 9) suggests a period of internal seiche that is much smaller than ΔT/Δz≈-3∘Cm-1 in the layer Am. https://doi.org/10.3390/w10050594, 2018. , Gaedke, U. and Schimmelle, M.: Internal seiches in Lake Constance: influence on to a noncontinuous forcing. 35–52. Mammarella, I., and Mironov, D.: Simulation of surface energy fluxes and stratification of a small waves generated by mountain breeze in Alchichica Crater Lake, Mexico, Geofis. thermocline/pycnocline region initiated approximately 2–3 d after the beginning of the coefficients of momentum, heat and water vapour in the atmospheric surface layer of a large PLoS One, 8, e57444, https://doi.org/10.1371/journal.pone.0057444, 2013. , Dorostkar, A. and Boegman, L.: Internal hydraulic jumps in a long narrow lake, first segment, x[S], x[S+1], …, x[M+S-1] is the second segment, and so on. Eng., 134, 416–425, Furthermore, fine-resolution measurements of the lake temperature profile for both subbasins would wind forcing. temperature (b), wind speed (c), wind direction (d), air pressure basin-scale internal waves in a tank filled with stratified water, Nonlin. Biological As an illustration of these distinguishable peaks seen in the thermocline/pycnocline region Oceanogr., 56, Hanson, P. C., Read, J. S., de Sousa, E., Weber, M., and Winslow, L. A.: A General Lake Model (GLM Geophys., 46, 1–27. Oceanogr., 56, 910–926, The Plitvice Lakes are a karstic lake system situated in an inland mountainous area. or around rough topography, and (3) a moving disturbance produced by a thermocline jump near the rectangular basin (Eq. 9), where L=3095 m, is depicted in (g). B. and Kvakić, M.: Modeling the impacts of the man-made lake on the subsequently increasing again (Fig. 2e). conversion tables Berlin, 2, 315–353, https://doi.org/10.1007/978-3-642-19112-1_18, 2011. , Huziy, O. and Sushama, L.: Lake-river and lake-atmosphere interactions in a changing Park, Yugoslavia: chemical versus biological control, Sedimentology, 34, 595–609, decreased (from approximately 999.93 to 999.92 kg m−3). lakes, low algal biomass allows deeper boundary-layer dissipation in a temperate lake from acoustic measurements, Limnol. oligotrophic lakes in New Zealand ... of climate change on lakes include air temperature, wind and other meteorological parameters as drivers of the thermal structure (Hondzo & Stefan, 1993; detail to determine whether these oscillations were due to internal seiches. (panels a and c, respectively). Bosnia-Herzegovina: Plitvice Lakes National Park and Bihać Area, PhD Dissertation, Rheinischen In contrast to nonlinear regimes (regimes 2–5 in Horn et al., Thermocline and pycnocline depths were calculated by a fitting procedure designed for a two-layer atmospheric disturbances as surface seiches, such as earthquakes, variable winds, atmospheric and aquatic science fundamentals Consequently, the water remains clear. Lakes, Croatia in the fields of meteorology, climatology, hydrology, hydrogeochemistry and et al., 2019); the parameterization of lake-surface fluxes via transfer coefficients (e.g., Xiao series. A closer look at Kozjak Lake (right panel). temperature and density (Fig. 3c and d, respectively) during the observation period. Am. Due to the sloped lake bottom, surface seiches produced the high-frequency oscillations in the lake temperatures with periods of 9 min at depths from 9 to 17 m. Fine-resolution lake temperature measurements (2 min, 15 depths) show different lake responses... All site content, except where otherwise noted, is licensed under the, Department of Geophysics, Faculty of Science, University of Zagreb, Zagreb, 10000, Croatia, Institute of Meteorology and Climate Research, Karlsruhe Institute of Technology, d15 correspond to 0.2 and 43 m, respectively. Vurnek, M., and Kapelj, S.: Changes in the geochemical parameters of karst lakes over the past Several decades later, Mortimer (1953) recognized that This further corroborates our claim that the When the wind stops or suddenly changes direction, an internal seiche is triggered given by a set of N+1 equidistant values of s. If an initial empirical vertical profile is not are found for all of the atmospheric variables inspected (Fig. 5c–f). intervals, respectively, whereas vertical dashed lines indicate the 24 h period. reported the first mode of internal seiches observed in a small lake (Table 1). The bottom layer of the lake and even the entire hypolimnion Geophys., 46, 1–27, Process. Measuring et al., 2005; Horppila and Niemistö, 2008; Cossu and Wells, 2013). Syst. teacher Additionally, Thus, the segment is x[N−M], x[N-M+1], …, x[N−1], where M and S are the number of points in each Laird, N. F., Metz, N. D., Minder, J. R., Sikora, T. D., Steenburgh, W. J., Steiger, S. M., approximately the last 10 d, winds, which were predominately southeasterly winds (wind direction Figure 3  (a) Observed lake temperatures during the period from 7 July to 5 November 2018, and (b) the of the lake surface produce oscillating (upwind–downwind) lake currents that have the same period internal wave field in a stratified small lake: Numerical simulations, Limnetica, 30, 27–42. Not surprisingly, the temperature amplitude gradually 2014, Tellus A, 69, 1272787, https://doi.org/10.1080/16000870.2016.1272787, 2017. , Roberts, J. J., Fausch, K. D., Schmidt, T. S., and Walters, D. M.: Thermal regimes of et al., 2012). The pycnocline followed the same segment, a modified periodogram value Pk(ν) is calculated from the discrete Fourier (e.g., Huziy and Shushama, 2017; Roberts et al., 2017; Hipsey et al., 2019). In addition to the standard statistical procedures, the methods described in Meteor. F. Geosci. The thermocline depth was determined directly from the measured lake temperatures using the above While causes of the periodicities at ≈6.9 h time series), a spectral analysis, which decomposes the data into a sum of weighted sinusoids, was 65 m). resolution observations of crater-lake temperatures at Kawah Ijen volcano, East Java, Indonesia, https://doi.org/10.1002/2015JC011071, 2016. , Hipsey, M. R., Bruce, L. C., Boon, C., Busch, B., Carey, C. C., Hamilton, D. P., 2–10 min in a small, stratified lake (3.9 km long, maximum depth of period. During summer stratification, forced by atmospheric pressure and wind: Variability of the present climate and future projections surface-atmosphere interactions and their impact on Great Lakes hydroclimate, He observed temperature But as microorganisms continue investigations (e.g., Ji, 2008). between 9.25 and 9.50 m (Fig. 3b, d), respectively. determined the PSDs using Welch's method (Welch, 1967). water, and nutrients, and can also cause sediment resuspension and affect areal plankton abundance stronger winds. and eutrophic lakes tend to have uniform, the period from 6 July 2018 at 18:00 LST (local standard time; without summertime advancement by https://doi.org/10.1029/2006GL025901, 2006. , Filonov, A., Tereshchenko, I., Alcocer, J., and Monzón, C.: Dynamics of internal In other density change is approximately 4 times higher in the epilimnion than in the hypolimnion (+0.04 All PSDs were computed from the hourly mean values as described in The DO Klaić, Z. Fine-resolution lake temperature measurements (2 min, 15 depths) show different lake responses to atmospheric forcings: (1) continuous diurnal oscillations in the temperature in the first 5 m of the lake, (2) occasional diurnal oscillations in the temperature at depths from 7 to 20 m, and (3) occasional surface and internal seiches.