scholarly journals Satellite-derived light extinction coefficient and its impact on thermal structure simulations in a 1-D lake model

2017 ◽  
Vol 21 (1) ◽  
pp. 377-391 ◽  
Author(s):  
Kiana Zolfaghari ◽  
Claude R. Duguay ◽  
Homa Kheyrollah Pour
Keyword(s):  
Water Temperature ◽  
Extinction Coefficient ◽  
Lake Erie ◽  
Thermal Structure ◽  
Meteorological Station ◽  
Light Extinction ◽  
Bottom Water Temperature ◽  
Column Temperature ◽  
Kd Values ◽  
The Impact

Abstract. A global constant value of the extinction coefficient (Kd) is usually specified in lake models to parameterize water clarity. This study aimed to improve the performance of the 1-D freshwater lake (FLake) model using satellite-derived Kd for Lake Erie. The CoastColour algorithm was applied to MERIS satellite imagery to estimate Kd. The constant (0.2 m−1) and satellite-derived Kd values as well as radiation fluxes and meteorological station observations were then used to run FLake for a meteorological station on Lake Erie. Results improved compared to using the constant Kd value (0.2 m−1). No significant improvement was found in FLake-simulated lake surface water temperature (LSWT) when Kd variations in time were considered using a monthly average. Therefore, results suggest that a time-independent, lake-specific, and constant satellite-derived Kd value can reproduce LSWT with sufficient accuracy for the Lake Erie station. A sensitivity analysis was also performed to assess the impact of various Kd values on the simulation outputs. Results show that FLake is sensitive to variations in Kd to estimate the thermal structure of Lake Erie. Dark waters result in warmer spring and colder fall temperatures compared to clear waters. Dark waters always produce colder mean water column temperature (MWCT) and lake bottom water temperature (LBWT), shallower mixed layer depth (MLD), longer ice cover duration, and thicker ice. The sensitivity of FLake to Kd variations was more pronounced in the simulation of MWCT, LBWT, and MLD. The model was particularly sensitive to Kd values below 0.5 m−1. This is the first study to assess the value of integrating Kd from the satellite-based CoastColour algorithm into the FLake model. Satellite-derived Kd is found to be a useful input parameter for simulations with FLake and possibly other lake models, and it has potential for applicability to other lakes where Kd is not commonly measured.

scholarly journals Satellite-Derived Light Extinction Coefficient and its Impact on Thermal Structure Simulations in a 1-D Lake Model

2016 ◽  
Author(s):  
Kiana Zolfaghari ◽  
Claude R. Duguay ◽  
Homa Kheyrollah Pour
Keyword(s):  
Water Temperature ◽  
Extinction Coefficient ◽  
Lake Erie ◽  
Thermal Structure ◽  
Weather Prediction ◽  
Light Extinction ◽  
Light Extinction Coefficient ◽  
Kd Values ◽  
Yearly Average ◽  
The Impact

Abstract. One essential optical parameter to specify in lake models is water clarity, which is parameterized based on the light extinction coefficient (Kd). A global constant value of Kd is usually specified in lake models. One-dimensional (1-D) lake models are most often used as lake parameterization schemes in numerical weather prediction and regional climate models. This study aimed to improve the performance of the 1-D Freshwater Lake (FLake) model using satellite-derived Kd for Lake Erie. The CoastColour algorithm is applied to MERIS satellite imagery to estimate Kd and evaluated against Kd derived from Secchi disk depth (SDD) field-based measurements collected during Lake Erie cruises. A good agreement is found between field and satellite-derived Kd (RMSE = 0.63 m-1, MBE = −0.09 m-1, I_a = 0.65) (in situ data was collected in 2004, 2005, 2008, 2011, 2012). The constant (0.2 m-1) and satellite-derived Kd values as well as radiation fluxes and meteorological station observations are then used to run FLake at the location of a buoy where lake surface water temperature (LSWT) was measured in 2008. Results improved compared to using a constant Kd value (0.2 m-1) (lake-specific yearly average Kd value: RMSE = 1.54 ºC, MBE = −0.08 ºC; constant Kd value: RMSE = 1.76 ºC, MBE = −1.26 ºC). No significant improvement is found in FLake simulated LSWT when Kd variations in time are considered using a monthly average. Therefore, results suggest that a time-independent, lake-specific, and constant satellite-derived Kd value can reproduce LSWT with sufficient accuracy. A sensitivity analysis is also performed to assess the impact of various Kd values on the simulation of mean water column temperature (MWCT), mixed layer depth (MLD), water temperature isotherms as well as ice dates and thickness. Results show that FLake is sensitive to variations in Kd to estimate the thermal structure of Lake Erie. Dark waters result in warmer spring and colder fall temperatures compare to clear waters. Dark waters always produce warmer MWCT, shallower MLD, longer ice cover duration, and thicker ice. The sensitivity of FLake to Kd variations is more pronounced in the simulation of MWCT and MLD. The model is particularly sensitive to Kd values below 0.5 m-1. This is the first study to assess the value of integrating Kd from the satellite-based CoastColour algorithm into the FLake model. Satellite-derived Kd is found to be a useful input parameter for simulations with FLake and possibly other lake models, and with potential for applicability to other lakes where Kd is not commonly measured.

scholarly journals Evaluation of the WRF lake module (v1.0) and its improvements at a deep reservoir

2018 ◽  
Author(s):  
Fushan Wang ◽  
Guangheng Ni ◽  
William J. Riley ◽  
Jinyun Tang ◽  
Dejun Zhu ◽  
...  
Keyword(s):  
Water Temperature ◽  
Surface Property ◽  
Thermal Structure ◽  
Light Extinction ◽  
Temperature Profiles ◽  
Lake Surface ◽  
Deep Lakes ◽  
Coupled Models ◽  
Lakes And Reservoirs ◽  
Deep Reservoir

Abstract. Large lakes and reservoirs play important roles in modulating regional hydrological cycles and climate; however, their representations in coupled models remain uncertain. The existing lake module in the Weather Research and Forecasting (WRF) system (hereafter WRF-Lake), although widely used, did not accurately predict temperature profiles in deep lakes mainly due to poor lake surface property parameterizations and underestimation of heat transfer between lake layers. We therefore revised WRF-Lake by improving its (1) numerical discretization scheme; (2) surface property parameterization; (3) diffusivity parameterization for deep lakes; and (4) convection scheme, the outcome of which became WRF-rLake (i.e., revised lake model). We evaluated WRF-rLake by comparing simulated and measured water temperature at the Nuozhadu Reservoir, a deep reservoir in southwestern China. WRF-rLake performs better than its predecessor by reducing the root-mean-square-error (RMSE) against observed lake surface temperatures (LSTs) from 1.4 °C to 1.1 °C and consistently improving simulated vertical temperature profiles. We also evaluated the sensitivity of simulated water temperature and surface energy fluxes to various modelled lake processes and parameters. We found (1) large changes in surface heat fluxes (up to 60 W m−2) associated with the improved surface property parameterization and (2) that the simulated lake thermal structure depends strongly on the light extinction coefficient and vertical diffusivity. Although currently only evaluated at the Nuozhadu Reservoir, we expect that these model parameter and structural improvements could be universal and therefore recommend further testing at other deep lakes and reservoirs.

scholarly journals Quantifying the impact of release operations and weather conditions on the flow and temperature dynamics in the cascade-reservoir system

2018 ◽  
Vol 246 ◽  
pp. 01027
Author(s):  
Gang Chen ◽  
Yue Zhai ◽  
Hui Fan ◽  
Xing Fang ◽  
Chuanhai Wang
Keyword(s):  
Water Temperature ◽  
Air Temperature ◽  
Cold Water ◽  
Temperature Drop ◽  
Weather Conditions ◽  
Density Currents ◽  
Three Dimensional Model ◽  
Bottom Water Temperature ◽  
Reservoir System ◽  
The Impact

The objective of this study was to investigate the flow dynamics and temperature characteristics under different reservoir operation scenarios and weather conditions in the river-reservoir system, which can be used to set scientific guidelines for river management and conservation planning strategies. The calibrated three-dimensional model provided simulated unsteady water surface elevation, temperature, velocity and discharge at different layers (depths) in different locations. A series of operation scenarios were modeled to understand and quantify formation, propagation, and disappearance of density currents that are resulted from combinations of daily repeated large release (DRLR) of different durations and solar heating. DRLRs (140 m3/s) with longer durations pushed the bottom cold water further downstream and maintained the bottom water temperature cooler. Variations of weather conditions (e.g., drops of air temperature and solar radiation) directly controled variations of bottom-layer water temperature. The daily drop rate of bottom temperature was related to the rate and duration of air temperature drop. Under the practice for the water turbines running at downstream, it clearly showed the shocking withdrawal and stopping effect from the downstream operation. The velocity for the whole cross-section were almost increased with same magnitude of about 0.1 m/s at GOUS and JML.

Vertical Thermal Distribution at the near Dam Region of the Three Gorges Reservoir in the Initial Impoundment Period

2014 ◽  
Vol 889-890 ◽  
pp. 1649-1652
Author(s):  
L.Q. Dai ◽  
H.C. Dai ◽  
B.W. Wang
Keyword(s):  
Temperature Distribution ◽  
Water Temperature ◽  
Temperature Difference ◽  
Three Gorges Reservoir ◽  
Thermal Structure ◽  
Maximum Temperature ◽  
Three Gorges ◽  
Bottom Water Temperature ◽  
The Three Gorges Reservoir ◽  
The Three Gorges

Water temperature plays a crucial role in water ecological environment both in the reservoir and downstream area. Three Gorges Project (TGP) is the largest hydraulic engineering in the world, and changes of water quality attract much more attention, especially in the thermal structure since initial impoundment in 2003. In order to clearly understand water temperature distribution after the initial impoundment in the Three Gorges Reservoir (TGR), we monitored the temperature distribution of the Taipingxi section which was not far from the dam from early April to the end of July in 2004. According to the analyzing of the monitoring data of transverse and vertical temperature variation, we could find that when water level went up to 135m above sea level (a.s.l.) or 139m in the initial impoundment phase, the temperature mixed uniformly in transverse direction. Excepting April, there was basically had no temperature difference in vertical direction, even in April, the maximum temperature difference was only 1.39°C within 100 meters (April 22), the average temperature gradient was only 0.014°C/m; Both the temperature of water and atmosphere have similar variation tendency, but the response of the water temperature to atmosphere is delayed, especially the bottom water temperature. The result indicate that the reservoir displayed a mixed thermal structure during initial impoundment phase, therefore, the release had no change before and after impoundment, also had little influence on the aquatic organism and crops at downstream , the work provide a scientific basis for the development of pollution control and ecological protection measure.

scholarly journals Using Water Temperature, Electrical Conductivity, and pH to Characterize Surface–Groundwater Relations in a Shallow Ponds System (Doñana National Park, SW Spain)

Water ◽  
2018 ◽  
Vol 10 (10) ◽  
pp. 1406 ◽  
Author(s):  
Miguel Rodríguez-Rodríguez ◽  
Ana Fernández-Ayuso ◽  
Masaki Hayashi ◽  
Francisco Moral-Martos
Keyword(s):  
Electrical Conductivity ◽  
Water Temperature ◽  
National Park ◽  
Discharge Rate ◽  
Thermal Structure ◽  
Groundwater Discharge ◽  
Transfer Model ◽  
Public Attention ◽  
Doñana National Park ◽  
Column Temperature

The physical limnology of a shallow pond system was characterized using field measurements of water temperature, pH, and electrical conductivity (EC). We determined the spatial variability in surface and groundwater temperature, pH, and EC along the pond’s shore and along the several pond-shore transects, analyzed the water column temperature gradient and estimated the groundwater discharge rate using a heat transfer model. The fieldwork was conducted in Santa Olalla and Dulce ponds located in Doñana National Park in southwestern Spain during different stages from 2016 to 2018. The results of this study have improved the understanding of the thermal structure and the surface–subsurface heat exchange in the ponds and highlighted the importance of groundwater discharge in the pond water balance. It also showed the heterogeneous nature of groundwater discharge through the bottom sediments of the Santa Olalla pond. These results are consistent with previous studies and strengthen the existing hydrological and limnological knowledge of these ponds located in the protected area which is receiving a great deal of public attention.

scholarly journals Thermal Structure of Water During the Summer in Lakes of the Polish Lowlands as a Result of their Varied Morphometry

2020 ◽  
Vol 20 (2) ◽  
pp. 89-95
Author(s):  
Rajmund Skowron
Keyword(s):  
Water Temperature ◽  
Thermal Stratification ◽  
Thermal Structure ◽  
Heat Content ◽  
Morphometric Parameters ◽  
Lake Basin ◽  
Structure Of Water ◽  
Basin Morphometry ◽  
The Impact ◽  
The Vertical Distribution

AbstractThe paper discusses the impact of lake morphometric parameters on the thermal structure of water during the period of summer stagnation. The summer period in the lakes is characterized by clearly expressed properties of the thermal structure of water, differentiating lakes from one another. The study was carried out on 141 lakes in northern Poland, for which at least 3 vertical water temperature measurements were taken in different years. They showed a significant influence of lake basin morphometry upon the thermal structure of water in lakes. In general, measurements of the vertical distribution of water temperature showed clear diversity, and depending on the depth also thermal layers (epi-, meta- and hypolimnion). The results of the analysis of 8 lake morphometric parameters and 10 thermal stratification parameters revealed the existence of significant dependencies between them. The best-preserved relations (statistically significant) occurred between the parameters characterizing the lake depth and meta- and hypolimnion properties, as well as the thermal stratification factor and heat content in a unit of volume.

scholarly journals Pliocene three-dimensional global ocean temperature reconstruction

2009 ◽  
Vol 5 (4) ◽  
pp. 769-783 ◽  
Author(s):  
H. J. Dowsett ◽  
M. M. Robinson ◽  
K. M. Foley
Keyword(s):  
Water Temperature ◽  
Deep Water ◽  
Bottom Water ◽  
Thermal Structure ◽  
Three Dimensional ◽  
The Arctic ◽  
Global Ocean ◽  
Validation Data ◽  
Data Set ◽  
Bottom Water Temperature

Abstract. The thermal structure of the mid-Piacenzian ocean is obtained by combining the Pliocene Research, Interpretation and Synoptic Mapping Project (PRISM3) multiproxy sea-surface temperature (SST) reconstruction with bottom water temperature estimates from 27 locations produced using Mg/Ca paleothermometry based upon the ostracod genus Krithe. Deep water temperature estimates are skewed toward the Atlantic Basin (63% of the locations) and represent depths from 1000 m to 4500 m. This reconstruction, meant to serve as a validation data set as well as an initialization for coupled numerical climate models, assumes a Pliocene water mass framework similar to that which exists today, with several important modifications. The area of formation of present day North Atlantic Deep Water (NADW) was expanded and extended further north toward the Arctic Ocean during the mid-Piacenzian relative to today. This, combined with a deeper Greenland-Scotland Ridge, allowed a greater volume of warmer NADW to enter the Atlantic Ocean. In the Southern Ocean, the Polar Front Zone was expanded relative to present day, but shifted closer to the Antarctic continent. This, combined with at least seasonal reduction in sea ice extent, resulted in decreased Antarctic Bottom Water (AABW) production (relative to present day) as well as possible changes in the depth of intermediate waters. The reconstructed mid-Piacenzian three-dimensional ocean was warmer overall than today, and the hypothesized aerial extent of water masses appears to fit the limited stable isotopic data available for this time period.

scholarly journals Monitoring and analysis of vertical thermal structure of the Three Gorges Reservoir

2019 ◽  
Vol 118 ◽  
pp. 03035
Author(s):  
Lingquan Dai ◽  
Haibo Liu ◽  
Wei Li ◽  
Zhengyang Tang ◽  
Yang Xu
Keyword(s):  
Temperature Distribution ◽  
Water Temperature ◽  
Temperature Difference ◽  
Three Gorges Reservoir ◽  
Thermal Structure ◽  
Maximum Temperature ◽  
Three Gorges ◽  
Bottom Water Temperature ◽  
The Three Gorges Reservoir ◽  
The Three Gorges

Water temperature plays a crucial role in water ecological environment both in the reservoir and downstream area. Three Gorges Project (TGP) is the largest hydraulic engineering in the world, and changes of water quality attract much more attention, especially in the thermal structure since impoundment. In order to clearly understand water temperature distribution after impoundment in the Three Gorges Reservoir (TGR), we monitored the temperature distribution of the Taipingxi section which was not far from the dam from early April to the end of July. According to the analyzing of the monitoring data of transverse and vertical temperature variation, we could find that the temperature mixed uniformly in transverse direction. Excepting April, there was basically had no temperature difference in vertical direction, even in April, the maximum temperature difference was only 1.39°C within 100 meters (April 22), the average temperature gradient was only 0.014°C/m; Both the temperature of water and atmosphere have similar variation tendency, but the response of the water temperature to atmosphere is delayed, especially the bottom water temperature. The result indicate that the reservoir has mixed thermal structure during impoundment phase, so the release temperature had little change after the impoundment, the work provide a scientific basis for the development of pollution control and ecological protection measure.

Characteristic of Thermal Structure in Reservoir in Different Climate Zones

2013 ◽  
Vol 807-809 ◽  
pp. 1634-1643 ◽  
Author(s):  
Ding Guo Jiang ◽  
Yu Jing Bie ◽  
Wei Liu
Keyword(s):  
Water Temperature ◽  
Thermal Stratification ◽  
Thermal Structure ◽  
Water Environment ◽  
Three Dimensional ◽  
Temperature Structure ◽  
Climatic Region ◽  
Reservoir Water ◽  
Discharge Water ◽  
The Impact

A three dimensional mathematical model was used to simulates water temperature structure of a model reservoir under the southwest plateau climate and the subtropics monsoon climate separately. The calculated result shows that: 1. in the Southwest plateau climatic region, obvious double convection was noticed of the surface water, while single convection appears in subtropics monsoon climatic region. 2. Thermal stratification in tropics monsoon climatic region is steadier than the southwest plateau climatic region. 2. In the subtropics monsoon climatic region the water temperature difference between discharge and natural water is more remarkable than the Southwest plateau climatic region, namely that in the subtropics monsoon climatic region the impact of discharge water on downstream water temperature is more appreciable. The research conclusion may provide reference and the basis for the contrastive analysis of related achievement in reservoir water temperature and the water environment.

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