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Assessment with Controlled In-Situ Data of the Dependence of L-Band Radiometry on Sea-Ice Thickness
摘要： The European Space Agency (ESA) Soil Moisture and Ocean Salinity (SMOS) and the National Aeronautics and Space Administration (NASA) Soil Moisture Active Passive (SMAP) missions are providing brightness temperature measurements at 1.4 GHz (L-band) for about 10 and 4 years respectively. One of the new areas of geophysical exploitation of L-band radiometry is on thin (i.e., less than 1 m) Sea Ice Thickness (SIT), for which theoretical and empirical retrieval methods have been proposed. However, a comprehensive validation of SIT products has been hindered by the lack of suitable ground truth. The in-situ SIT datasets most commonly used for validation are affected by one important limitation: They are available mainly during late winter and spring months, when sea ice is fully developed and the thickness probability density function is wider than for autumn ice and less representative at the satellite spatial resolution. Using Upward Looking Sonar (ULS) data from the Woods Hole Oceanographic Institution (WHOI), acquired all year round, permits overcoming the mentioned limitation, thus improving the characterization of the L-band brightness temperature response to changes in thin SIT. State-of-the-art satellite SIT products and the Cumulative Freezing Degree Days (CFDD) model are veri?ed against the ULS ground truth. The results show that the L-band SIT can be meaningfully retrieved up to 0.6 m, although the signal starts to saturate at 0.3 m. In contrast, despite the simplicity of the CFDD model, its predicted SIT values correlate very well with the ULS in-situ data during the sea ice growth season. The comparison between the CFDD SIT and the current L-band SIT products shows that both the sea ice concentration and the season are fundamental factors in?uencing the quality of the thickness retrieval from L-band satellites.
关键词： sea ice thickness,retrieval model validation,upward looking sonar,Arctic,Soil Moisture Active Passive (SMAP),Soil Moisture and Ocean Salinity (SMOS) mission,L-band radiometry
更新于2025-09-23 15:19:57
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Mathematical model development and optimal design of the horizontal all-glass evacuated tube solar collectors integrated with bottom mirror reflectors for solar energy harvesting
摘要： As one of the inexhaustible energy sources, solar energy as a means to provide space heating has been a public interest for decades. Many stand-alone solar thermal technologies have come into practice to replace the out-of-date systems. However, conventional solar thermal systems present two drawbacks: (1) unsteady solar sources can lead to insufficient heating in the winter, and (2) the solar collectors can become overheated in the summer. Therefore, this study proposes a conceptual design of an integrated solar harvesting unit that consists of the horizontal all-glass evacuated tube solar collectors and bottom mirror reflectors to overcome the above drawbacks to the largest extent possible. To accomplish this, a generic mathematical model of this design unit was developed, followed by the model validation process and optimal design analysis. For cities in the severe cold and cold climate zones of northern China, the bottom mirror reflectors can be regarded as solar energy collection boosters during the heating season, which can contribute solar energy ranging from 40% to 80% of the total collected solar energy depending on the inclined angles of the solar collectors and reflectors. In the summer, using such integrated unit with the solar collectors tilted at an obtuse angle, the absorbed solar radiation can be reduced by 20%, which is beneficial to overheating prevention.
关键词： Horizontal evacuated tube solar collector,Mathematical model,Optimal design,Bottom mirror reflector,Model validation
更新于2025-09-19 17:15:36
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[IEEE 2019 IEEE Innovative Smart Grid Technologies - Asia (ISGT Asia) - Chengdu, China (2019.5.21-2019.5.24)] 2019 IEEE Innovative Smart Grid Technologies - Asia (ISGT Asia) - Review on modeling of photovoltaic power generation systems
摘要： In recent years, photovoltaic (PV) power generation has developed rapidly at China and abroad. PV power generation is on the trend from auxiliary power supply to main power supply even leading power supply. Due to the fluctuation and intermittent characteristics of PV power generation, and zero inertia, the integration of large-scale grid-connected PV power generation may have a negative impact on the stability of the power system. Modeling grid-connected PV power generation systems is the key factor to investigate the influence between it and other parts of power system. Modeling of PV is also a hot issue that has been studied continuously for many years around the world. GE, WECC, CIGRE, CEPRI and so on have attached great importance to this issue and have published many research results. The existing research at China and abroad is reviewed in this paper, the existing problems are analyzed, and suggestions for future research are given.
关键词： power plant,model validation,photovoltaic (PV) power generation,power unit,modeling
更新于2025-09-16 10:30:52
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Total Global Solar Radiation Estimation with Relative Humidity and Air Temperature Extremes in Ireland and Holland
摘要： Solar radiation is the earth’s primary energy source for all biochemical and physical activities. Accurate knowledge of the solar radiation is important in engineering applications. This study aimed to calibrate some of the existing models in the literature for estimating daily total global solar radiation parameter using available measuring records (maximum and minimum air temperatures) and new models were developed based on maximum and minimum air temperatures, relative humidity and relative humidity extremes. Applicability of the Hargreaves model, Allen model, Bristow-Campbell model and Chen model were evaluated for computing the daily total solar global radiation, the geographical and meteorological data of Irish and Dutch cities were used. Meteorological data were taken from Royal Netherlands Meteorological Institute and Irish Meteorological Service. The models were compared on the basis of error tests which were mean percentage error (MPE), mean bias error (MBE), root mean square error (RMSE) and Nash-Sutcliffe equation (NSE). And, monthly MPE errors were given for each model. This study proposed new estimation models which were based on daily average relative humidity, relative humidity extremes and temperature extremes. Error analyses were applied to these models and results were given in the study.
关键词： Holland,solar radiation,model validation,temperature,daily total global solar radiation,relative humidity,model comparison,Ireland,meteorological models
更新于2025-09-04 15:30:14