scholarly journals Evolution and dynamics of the vertical temperature profile in an oligotrophic lake

2020 ◽  
Vol 24 (7) ◽  
pp. 3399-3416
Author(s):  
Zvjezdana B. Klaić ◽  
Karmen Babić ◽  
Mirko Orlić
Keyword(s):  
Heat Fluxes ◽  
Lake Surface ◽  
Vertical Temperature ◽  
Vertical Temperature Profile ◽  
Different Types ◽  
Lake Temperature ◽  
Realistic Topography ◽  
Internal Seiches ◽  
Continuous Heat ◽  
Observation Period

Abstract. In this study, the fine-scale responses of a stratified oligotrophic karstic lake (Kozjak Lake, Plitvice Lakes, Croatia; the lake fetch is 2.3 km, and the maximum depth is 46 m) to atmospheric forcing on the lake surface are investigated. Lake temperatures measured at a resolution of 2 min at 15 depths ranging from 0.2 to 43 m, which were observed during the 6 July–5 November 2018 period, were analyzed. The results show thermocline deepening from 10 m at the beginning of the observation period to 16 m at the end of the observation period, where the latter depth corresponds to approximately one-third of the lake depth. The pycnocline followed the same pattern, except that the deepening occurred throughout the entire period approximately 1 m above the thermocline. On average, thermocline deepening was 3–4 cm d−1, while the maximum deepening (12.5 cm d−1) coincided with the occurrence of internal seiches. Furthermore, the results indicate three different types of forcings on the lake surface; two of these forcings have diurnal periodicity – (1) continuous heat fluxes and (2) occasional periodic stronger winds – whereas forcing (3) corresponds to occasional nonperiodic stronger winds with steady along-basin directions. Continuous heat fluxes (1) produced forced diurnal oscillations in the lake temperature within the first 5 m of the lake throughout the entire observation period. Noncontinuous periodic stronger winds (2) resulted in occasional forced diurnal oscillations in the lake temperatures at depths from approximately 7 to 20 m. Occasional strong and steady along-basin winds (3) triggered both baroclinic internal seiches with a principal period of 8.0 h and barotropic surface seiches with a principal period of 9 min. Lake currents produced by the surface seiches under realistic-topography conditions generated baroclinic oscillations of the thermocline region (at depths from 9 to 17 m) with periods corresponding to the period of surface seiches (≈ 9 min), which, to the best of our knowledge, has not been reported in previous lake studies.

scholarly journals Evolution and dynamics of the vertical temperature profile in an oligotrophic lake

2020 ◽  
Author(s):  
Zvjezdana B. Klaić ◽  
Karmen Babić ◽  
Mirko Orlić
Keyword(s):  
Air Temperature ◽  
Heat Fluxes ◽  
Temperature Pattern ◽  
Lake Surface ◽  
Observational Period ◽  
Vertical Temperature Profile ◽  
Near Surface ◽  
Lake Temperature ◽  
Internal Seiches ◽  
Continuous Heat

Abstract. Abstract. In this study, the fine-scale responses of a stratified oligotrophic karstic lake (Kozjak, Plitvice Lakes, Croatia; lake fetch is 2.3 km and maximum depth is 46 m) to atmospheric forcings on the lake surface are investigated. Lake temperatures measured at a resolution of 2 min at 15 depths ranging from 0.2 to 43 m, which were observed during the 6 July–5 November 2018 period were analyzed. The results show thermocline deepening from 10 m at the beginning, to 16 m at the end of the observational period, where the latter corresponds to approximately one third of the lake depth. The pycnocline followed the same pattern, except that the deepening occurred throughout the entire period approximately 1 m above the thermocline. On average, thermocline deepening was 3–4 cm per day, while the maximum deepening (12.5 cm per day) coincided with the occurrence of internal seiches. Furthermore, the results indicate three different types of forcings on the lake surface, and two of these forcings have diurnal periodicity: (1) continuous heat fluxes and (2) occasional periodic stronger winds, while the (3) forcing corresponds to occasional nonperiodic stronger winds with along the basin-steady directions. Continuous heat fluxes (1) produced forced diurnal oscillations in the lake temperature within the first 5 meters of the lake throughout the entire observational period. Noncontinuous periodic stronger winds (2) resulted in occasional forced diurnal oscillations in the lake temperatures at depths from approximately 7 to 20 m. Occasional steady along-the-basin stronger winds (3) triggered both, baroclinic internal seiches with a principal period of 8.0 h, and, barotropic surface seiches with a principal period of 9 min. Lake currents produced by the surface seiches under realistic-topography conditions generated baroclinic oscillations of the thermocline region (at depths of 9–17 m) with periods corresponding to the period of surface seiches (≈ 9 min), which to our knowledge, has not been reported in previous lake studies. Finally, a simple multiple linear regression model of the near-surface temperature (0.2 m), which depends on the air temperature and wind speed, can only be used as a rough estimate of the daily mean lake temperature under weak wind and undisturbed air temperature pattern conditions.

scholarly journals SIMO v1.0: Simplified model of the vertical temperature profile in a small warm monomictic lake

2021 ◽  
Author(s):  
Kristina Šarović ◽  
Zvjezdana Klaić
Keyword(s):  
Temperature Profile ◽  
Model Performance ◽  
Ultraviolet B ◽  
Maximum Depth ◽  
Meteorological Variables ◽  
Thermocline Depth ◽  
Vertical Temperature ◽  
Vertical Temperature Profile ◽  
Lake Temperature ◽  
Water Temperature Data

Abstract. A simple 1-D energy budget model (SIMO) for the prediction of the vertical temperature profiles in small, monomictic lakes forced by a reduced number of input meteorological variables is proposed. The model estimates the net heat flux and thermal diffusion using only routinely measured hourly mean meteorological variables (namely, the air temperature, relative humidity, atmospheric pressure, wind speed, and precipitation), hourly mean ultraviolet B radiation (UVB), and climatological monthly mean cloudiness data. Except for the initial vertical temperature profile, the model does not use any lake-specific variables. The model performance was evaluated against lake temperatures measured continuously during an observational campaign in two lakes belonging to the Plitvice Lakes, Croatia (Lake 1 and Lake 12). Temperatures were measured at 15 and 16 depths ranging from 0.2 to 27 in Lake 1 (maximum depth of 37.4 m) and 0.2 to 43 m in Lake 12 (maximum depth of 46 m). A sensitivity analysis of the simulation length was performed for simulation lengths from 1 to 30 days. The model performed reasonably well and it was able to satisfactorily reproduce the vertical temperature profile at the hourly scale, the deepening of the thermocline with time, and the annual variation in the vertical temperature profile. A yearlong simulation initiated with an approximately constant vertical profile of the lake temperature (≈ 4 °C) was able to reproduce the onset of stratification and convective overturn. However, the thermocline depth was underestimated while the epilimnion temperatures were overestimated. Nevertheless, the values of the model performance measures obtained for a yearlong simulation were comparable with those reported for other more complex models. Thus, the presented model can be used for the assessment of the onset and duration of lake stratification periods when water temperature data are unavailable, which can be useful for various lake studies performed in other scientific fields, such as biology, geochemistry, and sedimentology.

scholarly journals Internal seiches in a karstic mesotrophic lake (Prošće, Plitvice Lakes, Croatia)

Geofizika ◽  
2020 ◽  
Vol 37 (2) ◽  
pp. 157-179
Author(s):  
Zvjezdana B. Klaić ◽  
Karmen Babić ◽  
Tomislav Mareković
Keyword(s):  
Observational Period ◽  
Vertical Temperature ◽  
Power Spectral ◽  
Power Spectral Densities ◽  
Second Mode ◽  
Temperature Experiment ◽  
Lake Temperature ◽  
Internal Seiches ◽  
Insight Into ◽  
Plitvice Lakes

A lake temperature experiment was performed at the Prošće, Plitvice Lakes, Croatia during a 4-month observational period (6 July–4 November, 2019) to investigate the occurrence and characteristics of internal seiches in the lake. Two-minute mean lake temperatures were measured at a single lake point at fifteen depths ranging from 0.2 to 27 m. Analysis of these data provided insight into the previously unknown and rather complex Prošće Lake seiching. Power spectral densities (PSDs) and magnitude-squared coherences (γ2), together with corresponding cross-spectrum phases that were obtained from the hourly mean lake temperature, air pressure and wind speed data, suggested the presence of three vertical modes of an internal seiche. The first mode (V1H1, period of 6.09 h) corresponds to free baroclinic oscillations; the second mode (V2H1, period of 11.64 h) and the third mode (V3H1, period of 25.60 h) are associated with forced baroclinic oscillations of the lake interior. Excitation of the higher vertical modes is attributed to the influence of dense tributary water. Due to this water influence, vertical temperature gradients in the lake interior were relatively weak; consequently, a single thick metalimnion and/or two metalimnetic layers were established, which resulted in the presence of the V2H1 and V3H1 modes, respectively. Additionally, due to the influence of tributary water, the lake did not attain the typical stratification that is characterized by hypolimnetic temperatures of ≈ 4°C. Instead, during the entire observational period, the hypolimnetic temperatures were consistently above 7.6 °C.

scholarly journals EFFECT OF DUST AEROSOL LAYER ON VERTICAL TEMPERATURE PROFILE

MAUSAM ◽  
2022 ◽  
Vol 53 (4) ◽  
pp. 539-542
Author(s):  
A. P. DIMRI ◽  
V. K. JAIN ◽  
B. B. DASH
Keyword(s):  
Temperature Profile ◽  
Dust Aerosol ◽  
Aerosol Layer ◽  
Vertical Temperature ◽  
Vertical Temperature Profile

scholarly journals EXTRAPLEURAL PNEUMOLYSIS FOR CAVITARY PULMONARY TUBERCULOSIS TREATMENT

2020 ◽  
pp. 15-20
Author(s):  
P. G. Gadzhieva ◽  
D. B. Giller ◽  
A. A. Glotov ◽  
O. Sh. Kesaev ◽  
V. V. Koroev ◽  
...  
Keyword(s):  
Pulmonary Tuberculosis ◽  
Multidrug Resistant ◽  
Pathological Process ◽  
Tuberculosis Treatment ◽  
Long Term Results ◽  
Filling Material ◽  
Different Types ◽  
Positive Effect ◽  
Observation Period

Objective. To increase efficiency of cavitary pulmonary tuberculosis treatment by developing modern indications and technology of extrapleural pneumolysis with filling material.Material and methods. We reviewed 25 patients with cavitary pulmonary tuberculosis and bacterial excretion who had undergone extrapleural pneumolysis with different types of filling material in 2004–2015. In 16 cases, we performed surgery in patients with one lung.Results. 56% of operated patients demonstrated extensively drug-resistant TB, 40% had multidrug-resistant TB. Cavities were closed and bacterial excretion ceased in 92% of patients at discharge. Long-term results with observation period from 1 to 12 years were analyzed in 24 patients, 17 (71%) of them had complete clinical efficacy.Conclusion. Extrapleural pneumolysis is a mini-invasive surgical treatment that can prove positive effect in patients with non-fibrotic changes in a cavity wall and pathological process in upper parts of the lungs. 

scholarly journals A business transformation model to enhance the sustainability of small-sized family businesses

2021 ◽  
Vol 19 (1) ◽  
pp. 185-197
Author(s):  
Anita Wijayanti ◽  
Massila Kamalrudin ◽  
Safiah Sidek ◽  
Kartika Hendra Titisari
Keyword(s):  
Family Business ◽  
Environmental Changes ◽  
Transformation Process ◽  
Family Businesses ◽  
Transformation Model ◽  
Business Transformation ◽  
Doing Business ◽  
Different Types ◽  
Observation Period

Business transformation is essential to making the small-sized family business more sustainable. Technological and environmental changes have radically transformed the way of doing business. Business transformation into digital business is the key to success in these conditions. On the other hand, some of the previous studies of business transformation in several countries and industries show different empirical evidence. This study analyzes the transformation process in a small-sized family business. This is a case study of 15 small-sized family businesses with four different types of industry, with an interview and observation period of 12 months in 2019–2020. This study has formulated a business transformation model for a small-sized family business and presented the results of the transformation process carried out. The research results indicate that a business transformation model consists of several attributes and sub-attributes. Business transformation results indicate different processes and times between companies. In general, the transformation process can be grouped into the exploration, learning, and synchronizing stages. The industry with the fastest transformation process is the hospitality industry, while the manufacturing process for the industry takes a bit longer. The results of this study indicate that business transformation has improved the sustainability of a small-sized family business that is characterized by its ability to adapt to changing technology and environmental conditions.

scholarly journals Evidence of Climate Change Based on Lake Surface Temperature Trends in South Central Chile

2021 ◽  
Vol 13 (22) ◽  
pp. 4535
Author(s):  
Arnaldo Collazo Aranda ◽  
Daniela Rivera-Ruiz ◽  
Lien Rodríguez-López ◽  
Pablo Pedreros ◽  
José Luis Arumí-Ribera ◽  
...  
Keyword(s):  
Surface Temperature ◽  
Temperature Analysis ◽  
Lake Surface ◽  
Upward Trend ◽  
Climate Variability And Change ◽  
Central Chile ◽  
South Central ◽  
Temperature Trends ◽  
Physical Chemical ◽  
Lake Temperature

Lake temperature has proven to act as a good indicator of climate variability and change. Thus, a surface temperature analysis at different temporal scales is important, as this parameter influences the physical, chemical, and biological cycles of lakes. Here, we analyze monthly, seasonal, and annual surface temperature trends in south central Chilean lakes during the 2000–2016 period, using MODIS satellite imagery. To this end, 14 lakes with a surface area greater than 10 km2 were examined. Results show that 12 of the 14 lakes presented a statistically significant increase in surface temperature, with a rate of 0.10 °C/decade (0.01 °C/year) over the period. Furthermore, some of the lakes in the study present a significant upward trend in surface temperature, especially in spring, summer, and winter. In general, a significant increase in surface water temperature was found in lakes located at higher altitudes, such as Maule, Laja and Galletué lakes. These results contribute to the provision of useful data on Chilean lakes for managers and policymakers.

scholarly journals A Hydrodynamical Model for Calculating the Vertical Temperature Profile in Lakes During Cooling

1983 ◽  
Vol 14 (4) ◽  
pp. 239-254 ◽  
Author(s):  
Jörgen Sahlberg
Keyword(s):  
Heat Flux ◽  
Temperature Profile ◽  
Vertical Mixing ◽  
Hydrodynamical Model ◽  
Measured Temperature ◽  
Vertical Temperature ◽  
Mixing Rate ◽  
Mixing Processes ◽  
Vertical Temperature Profile ◽  
Radiation Fluxes

A one-dimensional hydrodynamical model is used for simulating the vertical temperature profile in a lake during cooling conditions. The vertical mixing rate is calculated by solving the equations for turbulent kinetic energy, k, and dissipation of energy, ε. The heat exchange between the water and atmosphere consists of the radiation fluxes, sensible and latent heat flux. Temperature measurements from Lake Väsman during November-December, 1981, were used in the verification study. The agreement between calculated and measured temperature profiles is very good. This indicates that both the mixing processes and the net heat flux are well described in the model.

scholarly journals 2.5D retrieval of atmospheric properties from exoplanet phase curves: application to WASP-43b observations

2020 ◽  
Vol 493 (1) ◽  
pp. 106-125 ◽  
Author(s):  
Patrick G J Irwin ◽  
Vivien Parmentier ◽  
Jake Taylor ◽  
Jo Barstow ◽  
Suzanne Aigrain ◽  
...  
Keyword(s):  
Temperature Profile ◽  
Water Vapour ◽  
Mole Fraction ◽  
Phase Curve ◽  
Vertical Temperature ◽  
Vertical Temperature Profile ◽  
Retrieval Technique ◽  
The Mean ◽  
Synthetic Phase ◽  
Model Phase

ABSTRACT We present a novel retrieval technique that attempts to model phase curve observations of exoplanets more realistically and reliably, which we call the 2.5-dimensional (2.5D) approach. In our 2.5D approach we retrieve the vertical temperature profile and mean gaseous abundance of a planet at all longitudes and latitudes simultaneously, assuming that the temperature or composition, x, at a particular longitude and latitude (Λ, Φ) is given by $x(\Lambda ,\Phi) = \bar{x} + (x(\Lambda ,0) - \bar{x})\cos ^n\Phi$, where $\bar{x}$ is the mean of the morning and evening terminator values of x(Λ, 0), and n is an assumed coefficient. We compare our new 2.5D scheme with the more traditional 1D approach, which assumes the same temperature profile and gaseous abundances at all points on the visible disc of a planet for each individual phase observation, using a set of synthetic phase curves generated from a GCM-based simulation. We find that our 2.5D model fits these data more realistically than the 1D approach, confining the hotter regions of the planet more closely to the dayside. We then apply both models to WASP-43b phase curve observations of HST/WFC3 and Spitzer/IRAC. We find that the dayside of WASP-43b is apparently much hotter than the nightside and show that this could be explained by the presence of a thick cloud on the nightside with a cloud top at pressure <0.2 bar. We further show that while the mole fraction of water vapour is reasonably well constrained to (1–10) × 10−4, the abundance of CO is very difficult to constrain with these data since it is degenerate with temperature and prone to possible systematic radiometric differences between the HST/WFC3 and Spitzer/IRAC observations. Hence, it is difficult to reliably constrain C/O.

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