scholarly journals Using Large-Aperture Scintillometer to Estimate Lake-Water Evaporation and Heat Fluxes in the Badain Jaran Desert, China

Water ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2575
Author(s):  
Han ◽  
Wang ◽  
Wang
Keyword(s):  
Water Temperature ◽  
Shallow Water ◽  
Time Scale ◽  
Open Water ◽  
Heat Fluxes ◽  
Accurate Estimation ◽  
Badain Jaran Desert ◽  
Large Aperture ◽  
Different Depths ◽  
Daily Time

Accurate estimation of evaporation (E0) over open water bodies in arid regions (e.g., lakes in the desert) is of great importance for local water resource management. Due to the ability to accurately determine sensible (H) and latent (LE) heat fluxes over scales of hundreds to thousands of meters, scintillometers are more and more appreciated. In this study, a scintillometer was installed on both sides of the shore over the Sumu Barun Jaran Lake in the Badain Jaran Desert and was applied to estimate the sensible and latent heat fluxes and evaporation to be compared with the data of an evaporation pan and an aerodynamic model. Based on the field data, we further analyzed the seasonal differences in the flux evaluation using water temperature at different depths at half-hour and daily time scales, respectively. The results showed that in cold seasons, values of H were barely affected by the changes of shallow water temperature, whereas in hot seasons, the values were changed by 20%–30% at the half-hour time scale and 6.2%–18.3% at the daily time scale. In different seasons, shallow water temperature at different depths caused changes in the range of 0%–20% of LE (E0). This study contributes to a better understanding of uncertainties in measurements by large-aperture scintillometers in open-water environments.

scholarly journals Estimating lake-water evaporation from data of large-aperture scintillometer in the Badain Jaran Desert, China, with two comparable methods

2018 ◽  
Vol 379 ◽  
pp. 433-442
Author(s):  
Peng-Fei Han ◽  
Xu-Sheng Wang ◽  
Xiaomei Jin ◽  
Bill X. Hu
Keyword(s):  
Surface Temperature ◽  
Water Temperature ◽  
Water Surface ◽  
Classical Method ◽  
Saturated Vapor ◽  
Open Water ◽  
Heat Fluxes ◽  
Badain Jaran Desert ◽  
Average Value ◽  
Water Surface Temperature

Abstract. Accurate quantification of evaporation (E0) from open water is vital in arid regions for water resource management and planning, especially for lakes in the desert. The scintillometers are increasingly recognized by researchers for their ability to determine sensible (H) and latent heat fluxes (LE) accurately over distances of hundreds of meters to several kilometers, though scintillometers are mainly used to monitor the land surface processes. In this paper, it is installed on both sides of the shore over a lake. Compared to the data of evaporationpan, the scintillometer was successfully applied to Sumu Barun Jaran in Badain Jaran Desert using the classical method and the proposed linearized β method. Due to the difficulty in measuring water surface temperature and the easiness to monitor the water temperature at different depths, it is worth thinking that if is feasible to utilize the shallow water temperature instead of the water surface temperature and how much errors it will cause. Water temperature at 10 and 20 cm depths were used to replace the lakewater surface temperature in the two methods to analyze the changes of sensible and latent heat fluxes in hot and cold seasons at halfhour time scales. Based on the classical method, the values of H were almost barely affected, and the average value of LE using water temperature at 20 cm depth is 0.8–9.5 % smaller than that at 10 cm depth in cold seasons. In hot seasons, compared to the results at 10 cm depth, the average value of H increased by 20–30 %, and LE decreased by about 20 % at 20 cm depth. In the proposed linearized β method of scintillometer, only the slope of the saturation pressure curve (Δ) is related to the water surface temperature, which was estimated using available equations of saturated vapor pressure versus temperature of the air. Compared to the values of estimated by the air temperature, while the water surface temperature are replaced by water temperature at 10 and 20 cm depths, in different seasons, the errors of 2–25 % in Δ were caused. Thus was calculated by the original equation in the proposed linearized β method of scintillometer. Interestingly, the water temperature at 10 and 20 cm depths had little effect on H, LE (E0) in different seasons. The reason is that the drying power of the air (EA) accounted for about 85 % of the evaporation (i.e. the changes of Δ have only about 3 % impact on evaporation), which indicated that the driving force from unsaturated to saturated vapor pressure at 2 m height (i.e. the aerodynamic portion) has the main role on evaporation. Therefore, the proposed linearized β method of scintillometer is recommended to quantify the H, LE (E0) over open water, especially when the water surface temperature cannot be accurately measured.

The intra-population variability of a freshwater crustacean Polyphemus pediculus (Cladocera, Onychopoda)

2019 ◽  
Vol 193 (2) ◽  
pp. 119-130
Author(s):  
Lyudmila G. Butorina
Keyword(s):  
Shallow Water ◽  
Deep Water ◽  
Local Population ◽  
Open Water ◽  
Temporal Variations ◽  
Total Length ◽  
Seasonal Races ◽  
Freshwater Crustacean ◽  
Different Depths ◽  
Number Of Individuals

A discriminant canonical analysis was employed to study the morphometric structure of a shallow-water local population during the open-water period, and of an autumn deep-water local population extending from the depths of 1.2 m to 23.6 m. Statistically treated data on 11 quantitative and 12 meristic features of 505 mature individuals from the shallow-water population and 294 specimens from the deep-water population were analyzed in the study. P. pediculus belongs to an ecologically polymorphic species. The morphometric structure of local populations of the species and its peculiarities are governed by the environmental conditions of the habitat and have an adaptive value. The population structure is unstable, subject to spatial and temporal variations together with the biotopic and seasonal variations of the environment. A continuous sympatric speciation proceeding in the populations leads to the formation of a number of phenotypes adapted to the existence in specific sub-niches. The morphometric structure of the shallow-water population is formed by three short-term seasonal races having statistically significant differences, and following in succession in correspondence with the change of season. Their morphometric diversity and variability reduce from spring to autumn; the highest statistically significant differences are peculiar to the autumn race. Crustaceans of the summer months do not display statistically significant differences between each other. Morphometric differences between seasonal races do not exceed the limits of the species variability range, and are conditioned mainly by variations in the total length of Ant II and in the number of setae in the medial rows of thoracic limbs of the I-III pairs. The morphometric structure of the deep-water population is more complex and stable, and is formed by three permanent morphoforms, which differ statistically significantly from each other and exist at different depths: the main (1.2–4.7 m), the intermediate (9.3 m) and the deep water (23.6 m). The degree and the accuracy of differences between the morphoforms increase with the depth of habitation. Permanent biotopic races are present at different depths within the morphoforms. The races of the intermediate and the deep-water morphoforms differ statistically significantly from the races of the main morphoform. The races of the main morphoform do not have any statistically significant differences between them. The number of crustaceans permanently present within the biotopic races increases with the habitation depth, and the number of individuals performing vertical migrations reduces. The deep-water morphoform is the most isolated and stable. A considerable divergence of quantitative features is observed in the specimens of this morphoform, resulting in the formation of a new species P. deepwater. Morphometric differences of the biotopic races are conditioned mainly by variations in the total length of Ant II, the length of the caudal stem and setae, Ant I free segments, the head diameter, and the number and length of setae on the third segments of endopodites of thoracic limbs of the I-III pairs.

Experimental Study of Heat Transfer in a Reduced Scale Cavity Incorporating Phase Change Material Into Its Vertical Walls

2017 ◽  
Vol 10 (1) ◽  
Author(s):  
Ayoub Gounni ◽  
Mustapha El Alami
Keyword(s):  
Heat Flux ◽  
Heat Source ◽  
Phase Change ◽  
Phase Change Material ◽  
Heat Fluxes ◽  
Surface Temperatures ◽  
Different Depths ◽  
Vertical Walls ◽  
Change Material ◽  
Reduced Scale

In order to really assess the thermal performance of a wall incorporating phase change material (PCM), a reduced scale cavity has been monitored during two heating cycles. For each cycle, the heat source inside the test cell is switched “on” for 5 h and its setpoint is 38 °C and then switched off for 4 h. The outdoor air temperature is kept constant at a low temperature of 20 °C. Two walls are equipped with a PCM layer at different depths in order to study the optimal PCM location. The two other walls are wooden and glass to model a real building. The comparison between the four walls is made based on the absorbed heat fluxes and outside surface temperatures. The results show that the location of the PCM close to the heat source reaches its melting temperature and then reduces the surface temperature. At this location, the PCM layer stores the major part of the inlet heat flux. It takes 10 h to release the absorbed heat flux. However, the PCM layer, practically, does not have an effect on the surface temperatures and absorbed heat fluxes, when it is placed far from the heat source.

Amphipod biodiversity of shallow water in the Taranto seas (north-western Ionian Sea)

2005 ◽  
Vol 85 (2) ◽  
pp. 333-338 ◽  
Author(s):  
E. Prato ◽  
F. Biandolino
Keyword(s):  
Shallow Water ◽  
Dominant Species ◽  
New Records ◽  
Maximum Depth ◽  
Ionian Sea ◽  
Number Of Species ◽  
Gammarus Aequicauda ◽  
Different Depths ◽  
North Western

This study was carried out to determine the amphipod fauna in Mar Piccolo, Mar Grande and the Gulf of Taranto. Material in this study was obtained from 96 stations at different depths (maximum depth: −50 m) using various methods depending on the substrata. A total of 65 species was determined and 25 species are new records in the seas of Taranto. Microdeutopus gryllotalpa, Ericthonius brasiliensis, Monocorophium insidiosum, Elasmopus rapax, Gammarus aequicauda, Gammarus insensibilis, Leucothoe spinicarpa, Lysianassa costae and Pseudoprotella phasma were the dominant species and have been found in all areas considered. The comparison of the data shows that the area examined presents a high difference regarding biocenotic index. The highest number of species was collected in the Gulf with 1944 individuals, belonging to 58 species and 19 families, followed by Mar Grande with 1448 individuals belonging to 36 species and 11 families; finally Mar Piccolo with 698 individuals, 12 species and 6 families, in the First Inlet and 546 individuals, 18 species and 6 families, in the Second Inlet.

scholarly journals Sub-daily runoff simulations with parameters inferred at the daily time scale

2015 ◽  
Vol 12 (8) ◽  
pp. 7437-7467 ◽  
Author(s):  
J. E. Reynolds ◽  
S. Halldin ◽  
C. Y. Xu ◽  
J. Seibert ◽  
A. Kauffeldt
Keyword(s):  
Time Series ◽  
Numerical Method ◽  
Time Scales ◽  
Time Scale ◽  
Input Data ◽  
Flood Forecasting ◽  
Euler Method ◽  
Time Stepping ◽  
Parameter Values ◽  
Daily Time

Abstract. Concentration times in small and medium-sized watersheds (~ 100–1000 km2) are commonly less than 24 h. Flood-forecasting models then require data at sub-daily time scales, but time-series of input and runoff data with sufficient lengths are often only available at the daily time scale, especially in developing countries. This has led to a search for time-scale relationships to infer parameter values at the time scales where they are needed from the time scales where they are available. In this study, time-scale dependencies in the HBV-light conceptual hydrological model were assessed within the generalized likelihood uncertainty estimation (GLUE) approach. It was hypothesised that the existence of such dependencies is a result of the numerical method or time-stepping scheme used in the models rather than a real time-scale-data dependence. Parameter values inferred showed a clear dependence on time scale when the explicit Euler method was used for modelling at the same time steps as the time scale of the input data (1–24 h). However, the dependence almost fully disappeared when the explicit Euler method was used for modelling in 1 h time steps internally irrespectively of the time scale of the input data. In other words, it was found that when an adequate time-stepping scheme was implemented, parameter sets inferred at one time scale (e.g., daily) could be used directly for runoff simulations at other time scales (e.g., 3 or 6 h) without any time scaling and this approach only resulted in a small (if any) model performance decrease, in terms of Nash–Sutcliffe and volume-error efficiencies. The overall results of this study indicated that as soon as sub-daily driving data can be secured, flood forecasting in watersheds with sub-daily concentration times is possible with model-parameter values inferred from long time series of daily data, as long as an appropriate numerical method is used.

scholarly journals Identifying robust bias adjustment methods for extreme precipitation in a pseudo-reality setting

2020 ◽  
Author(s):  
Torben Schmith ◽  
Peter Thejll ◽  
Peter Berg ◽  
Fredrik Boberg ◽  
Ole Bøssing Christensen ◽  
...  
Keyword(s):  
Time Scale ◽  
Extreme Value ◽  
Extreme Value Analysis ◽  
Climate Factor ◽  
Value Analysis ◽  
Model Simulations ◽  
Bias Adjustment ◽  
Return Levels ◽  
Hourly Data ◽  
Daily Time

Abstract. Severe precipitation events occur rarely and are often localized in space and of short duration; but they are important for societal managing of infrastructure. Therefore, there is a demand for estimating future changes in the statistics of these rare events. These are usually projected using Regional Climate Model (RCM) scenario simulations combined with extreme value analysis to obtain selected return levels of precipitation intensity. However, due to imperfections in the formulation of the physical parameterizations in the RCMs, the simulated present-day climate usually has biases relative to observations. Therefore, the RCM results are often bias-adjusted to match observations. This does, however, not guarantee that bias-adjusted projected results will match future reality better, since the bias may change in a changed climate. In the present work we evaluate different bias adjustment techniques in a changing climate. This is done in an inter-model cross-validation setup, in which each model simulation in turn plays the role of pseudo-reality, against which the remaining model simulations are bias adjusted and validated. The study uses hourly data from present-day and RCP8.5 late 21st century from 19 model simulations from the EURO-CORDEX ensemble at 0.11° resolution, from which fields of selected return levels are calculated for hourly and daily time scale. The bias adjustment techniques applied to the return levels are based on extreme value analysis and include analytical quantile-matching together with the simpler climate factor approach. Generally, return levels can be improved by bias adjustment, compared to obtaining them from raw scenarios. The performance of the different methods depends of the time scale considered. On hourly time scale, the climate factor approach performs better than the quantile-matching approaches. On daily time scale, the superior approach is to simply deduce future return levels from observations and the second best choice is using the quantile-mapping approaches. These results are found in all European sub-regions considered.

scholarly journals Peculiarities of the Pontogammarus robustoides (Amphipoda, Gammaridae) Adaptive Reactions to the Water Temperature Increasing in the Model Ecosystem – Microcosm

2021 ◽  
Vol 21 (08) ◽  
pp. 365-374
Author(s):  
Victor Romanenko ◽  
Olexander Romanenko ◽  
Yurii Krot ◽  
Anna Podruhina
Keyword(s):  
Climate Change ◽  
Energy Metabolism ◽  
Water Temperature ◽  
Shallow Water ◽  
Critical Values ◽  
Model Ecosystem ◽  
Functional Changes ◽  
Temperature Conditions ◽  
Pontogammarus Robustoides ◽  
Adaptive Reactions

The crustaceans’ family Gammaridae populations’ adaptive reactions with a water temperature increasing to the critical values were studied in the model ecosystem – the microcosm. The experiment included investigation of such indexes as population dimensional composition, precopulatory activity, number of oviparous females, embryogenesis duration, and energy metabolism at the different phases of thermocycle. Obtained data revealed optimal and critical for gammarid’s viability temperature conditions of environment. It is assumed that under conditions of climate change, when water temperature sharp fluctuations take place, in the Kyiv reservoir (Dnipro River, Ukraine) coastal shallow water crustacean’s family Gammaridae components of the invertebrates associations the structural and functional changes are expected. Temperature increasing to the critical values will promote the animals migration processes intensification; incapable of this animals will perish. Gammarids with ability to migrate in direction of areas with more favorable for their viability conditions will have a significant advantage.

scholarly journals Development and Integration of Sub-Daily Flood Modelling Capability within the SWAT Model and a Comparison with XAJ Model

Water ◽  
2018 ◽  
Vol 10 (9) ◽  
pp. 1263 ◽  
Author(s):  
Dachen Li ◽  
Simin Qu ◽  
Peng Shi ◽  
Xueqiu Chen ◽  
Feng Xue ◽  
...  
Keyword(s):  
Time Scale ◽  
Flood Control ◽  
Assessment Tool ◽  
Spatial Scales ◽  
Swat Model ◽  
Flood Forecasting ◽  
Base Flow ◽  
Flood Simulation ◽  
Promising Tool ◽  
Daily Time

To date, floods have become one of the most severe natural disasters on Earth. Flood forecasting with hydrological models is an important non-engineering measure for flood control and disaster reduction. The Xin’anjiang (XAJ) model is the most widely used hydrological model in China for flood forecasting, while the Soil and Water Assessment Tool (SWAT) model is widely applied for daily and monthly simulation and has shown its potential for flood simulation. The objective of this paper is to evaluate the performance of the SWAT model in simulating floods at a sub-daily time-scale in a slightly larger basin and compare that with the XAJ model. Taking Qilijie Basin (southeast of China) as a study area, this paper developed the XAJ model and SWAT model at a sub-daily time-scale. The results showed that the XAJ model had a better performance than the sub-daily SWAT model regarding relative runoff error (RRE) but the SWAT model performed well according to relative peak discharge error (RPE) and error of occurrence time of peak flow (PTE). The SWAT model performed unsatisfactorily in simulating low flows due to the daily calculation of base flow but behaved quite well in simulating high flows. We also evaluated the effect of spatial scale on the SWAT model. The results showed that the SWAT model had a good applicability at different spatial scales. In conclusion, the sub-daily SWAT model is a promising tool for flood simulation though more improvements remain to be studied further.

scholarly journals Core Temperature in Triathletes during Swimming with Wetsuit in 10 °C Cold Water

Sports ◽  
2019 ◽  
Vol 7 (6) ◽  
pp. 130 ◽  
Author(s):  
Jørgen Melau ◽  
Maria Mathiassen ◽  
Trine Stensrud ◽  
Mike Tipton ◽  
Jonny Hisdal
Keyword(s):  
Water Temperature ◽  
Skin Temperature ◽  
Core Temperature ◽  
Rectal Temperature ◽  
Physiological Response ◽  
Cold Water ◽  
Temperature Response ◽  
Open Water ◽  
Open Water Swimming ◽  
Ironman Distance

Low water temperature (<15 °C) has been faced by many organizers of triathlons and swim-runs in the northern part of Europe during recent years. More knowledge about how cold water affects athletes swimming in wetsuits in cold water is warranted. The aim of the present study was therefore to investigate the physiological response when swimming a full Ironman distance (3800 m) in a wetsuit in 10 °C water. Twenty triathletes, 37.6 ± 9 years (12 males and 8 females) were recruited to perform open water swimming in 10 °C seawater; while rectal temperature (Tre) and skin temperature (Tskin) were recorded. The results showed that for all participants, Tre was maintained for the first 10–15 min of the swim; and no participants dropped more than 2 °C in Tre during the first 30 min of swimming in 10 °C water. However; according to extrapolations of the results, during a swim time above 135 min; 47% (8/17) of the participants in the present study would fall more than 2 °C in Tre during the swim. The results show that the temperature response to swimming in a wetsuit in 10 °C water is highly individual. However, no participant in the present study dropped more than 2 °C in Tre during the first 30 min of the swim in 10 °C water.

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