scholarly journals A Simple Solution for Refining Lake Water Temperature Profiles Data Arrayed from High-Frequency Monitoring Sensors

2021 ◽  
Vol 6 (1) ◽  
pp. 25
Author(s):  
Arianto Budi Santoso ◽  
Endra Triwisesa ◽  
Muh Fakhrudin

The revolutionized aquatic monitoring sensors are essential in capturing environmental patterns that traditional discrete samplings might not be able to. They allow scientists to further synthesize and better conclude processes in aquatic ecosystems. These sensors produce high-frequency data that provide information on a fine temporal scale, even near real-time. The massive quantities of the streamed data, however, create challenges for scientists to grasp the concrete information. Filtering data quality, on the other hand, is another problem scientists might have encountered as sensor accuracy and precision may drift along the line. Hence, quality assurance and quality control might be quite labouring owing to the size of datasets to handle. This paper proposed a semi-mechanistic algorithm to improved false water temperature data. Using “theoretical” thermal stratification as a reference, this algorithm fixed sensors error readings. A 5-month dataset of water temperature profiles of Lake Maninjau, West Sumatra, captured every 10 minutes from a set of sensors in thermistor chain was applied. We found that most data fit to the theoretical temperature profile, R<sup>2</sup> = 0.962, RMSE = 0.081<sup>o</sup>C. A number of errors, however, were observed in the upper layer of the lake (&lt;20 m), the most dynamic layer in terms of its thermal variation. Sensor drifts in this active upper mixed layer can be related to the generated errors. Through this simple solution, not only improving the quality of the observed water temperature data, but was also able to identify the most probable source of errors

Water ◽  
2012 ◽  
Vol 4 (3) ◽  
pp. 597-606 ◽  
Author(s):  
Colin Sowder ◽  
E. Ashley Steel

2019 ◽  
Author(s):  
M.J. Kehoe ◽  
B.P. Ingalls ◽  
J.J. Venkiteswaran ◽  
H.M. Baulch

AbstractCyanobacterial blooms are causing increasing issues across the globe. Bloom forecasting can facilitate adaptation to blooms. Most bloom forecasting models depend on weekly or fortnightly sampling, but these sparse measurements can miss important dynamics. Here we develop forecasting models from five years of high frequency summer monitoring in a shallow lake (which serves as an important regional water supply). A suite of models were calibrated to predict cyanobacterial fluorescence (a biomass proxy) using measurements of: cyanobacterial fluorescence, water temperature, light, and wind speed. High temporal autocorrelation contributed to relatively strong predictive power over 1, 4 and 7 day intervals. Higher order derivatives of water temperature helped improve forecasting accuracy. While traditional monitoring and modelling have supported forecasting on longer timescales, we show high frequency monitoring combined with telemetry allows forecasting over timescales of 1 day to 1 week, supporting early warning, enhanced monitoring, and adaptation of water treatment processes.


2021 ◽  
Vol 13 (3) ◽  
pp. 1-17
Author(s):  
Zhicheng Liu ◽  
Yang Zhang ◽  
Ruihong Huang ◽  
Zhiwei Chen ◽  
Shaoxu Song ◽  
...  

IoT data with timestamps are often found with outliers, such as GPS trajectories or sensor readings. While existing systems mostly focus on detecting temporal outliers without explanations and repairs, a decision maker may be more interested in the cause of the outlier appearance such that subsequent actions would be taken, e.g., cleaning unreliable readings or repairing broken devices or adopting a strategy for data repairs. Such outlier detection, explanation, and repairs are expected to be performed in either offline (batch) or online modes (over streaming IoT data with timestamps). In this work, we present TsClean, a new prototype system for detecting and repairing outliers with explanations over IoT data. The framework defines uniform profiles to explain the outliers detected by various algorithms, including the outliers with variant time intervals, and take approaches to repair outliers. Both batch and streaming processing are supported in a uniform framework. In particular, by varying the block size, it provides a tradeoff between computing the accurate results and approximating with efficient incremental computation. In this article, we present several case studies of applying TsClean in industry, e.g., how this framework works in detecting and repairing outliers over excavator water temperature data, and how to get reasonable explanations and repairs for the detected outliers in tracking excavators.


Sign in / Sign up

Export Citation Format

Share Document