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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Wind Direction Ambiguity Removal Using Along-Track Insar: A Case Study
摘要： The main problem in wind retrieval using SAR imagery is the lack of the wind direction information. A few methods have been proposed to extract the wind direction from SAR images. The main limitation of these methods is the 180o ambiguity in the direction. Usually, an external source of wind direction is used to remove this ambiguity. This study exploits the Along-track Interferometric SAR (ATI-SAR) phase to demonstrate its usefulness to tackle this problem. A method is proposed to remove the wind direction ambiguity using the ATI-SAR phase information. This is based on the fact that the interferometric phase is related to the sea surface motion direction. Depending on the sign convention, the phase is positive/negative for advancing/receding target respectively. This effect is used to assist the wind extraction algorithm to select the most plausible direction. The results show a very good agreement with atmospheric model and visual investigation.
关键词： InSAR,TerraSAR-X,wind direction,ocean surface wind
更新于2025-09-23 15:22:29
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Southerly winds increase the electricity generated by solar photovoltaic systems
摘要： The urgent need to decarbonise energy supplies has prompted exponential growth of solar photovoltaic (PV) systems across the world. As the penetration of renewable energy sources increases, the need to accurately forecast electricity output heightens to ensure efficient energy system operation. While exposure to high temperatures and moisture are known to significantly reduce PV panel efficiency, the effects of wind on both PV panel temperature and electricity output are poorly resolved. Here, meteorological and PV panel production data from Westmill Solar Park, Oxfordshire, were examined to determine the influence of wind, cloud, ambient temperature and relative humidity. We found that, after solar radiation, relative humidity and cloud cover were the dominant controls of PV electricity output; increases in relative humidity and cloud cover were associated with decreased electricity outputs. However, when all other variables were held constant, the mean electricity generated under southerly winds was 20.4 – 42.9% greater than under northerly winds, with the difference greater at higher electricity outputs and attributable to differences in surface cooling capabilities caused by the PV array asymmetry. This finding suggests that PV electricity output predictions could be improved by incorporating wind direction into computer models. Moreover, there is potential to modify solar park design and deployment location to capitalise on wind benefits, especially in areas where panel temperatures are a leading cause of efficiency loss. Ensuring deployments are optimised for site environmental conditions could boost electricity outputs, and therefore profitability, with implications for system viability in post-subsidy markets.
关键词： Solar park design,Solar energy,Panel orientation,Temperature,Wind direction
更新于2025-09-23 15:21:01
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Validating precision estimates in horizontal wind measurements from a Doppler lidar
摘要： Results from a recent field campaign are used to assess the accuracy of wind speed and direction precision estimates produced by a Doppler lidar wind retrieval algorithm. The algorithm, which is based on the traditional velocity-azimuth-display (VAD) technique, estimates the wind speed and direction measurement precision using standard error propagation techniques, assuming the input data (i.e., radial velocities) to be contaminated by random, zero-mean, errors. For this study, the lidar was configured to execute an 8-beam plan-position-indicator (PPI) scan once every 12 min during the 6-week deployment period. Several wind retrieval trials were conducted using different schemes for estimating the precision in the radial velocity measurements. The resulting wind speed and direction precision estimates were compared to differences in wind speed and direction between the VAD algorithm and sonic anemometer measurements taken on a nearby 300 m tower.
关键词： VAD algorithm,precision estimates,wind speed,wind direction,Doppler lidar,sonic anemometer
更新于2025-09-10 09:29:36
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A New Hurricane Wind Direction Retrieval Method for SAR Images without Hurricane Eye
摘要： This study presents a new approach for hurricane wind direction retrieval utilizing rainband streaks contained in synthetic aperture radar (SAR) images without hurricane eye information, based on the hurricane inflow angle. To calculate the wind direction field, a method for estimating the location of the hurricane center is given. In this paper, four Sentinel-1A (S-1A) images with a hurricane eye are used to clarify the center estimation method. Three S-1A SAR images without a hurricane eye are studied to evaluate the accuracy of the new method. The estimated locations of hurricane centers show good agreement with hurricane track data provided by the National Oceanic and Atmospheric Administration (NOAA)’s Atlantic Oceanographic and Meteorological Laboratory (AOML) Hurricane Research Division (HRD), HurricaneCity, and the National Institute of Informatics (NII). To validate the estimated wind directions, the NOAA HRD dropwindsonde observations for Tropical Storm Karl are collected and compared. The wind directions retrieved by our approach are more consistent with visual inspection than the fast Fourier transform (FFT) method in subimages. Moreover, the retrieved wind speeds utilizing C-band model 5.N (CMOD5.N) are compared with wind speed estimations observed by Stepped Frequency Microwave Radiometer (SFMR). The results suggest that the proposed method has good potential to retrieve hurricane wind direction from SAR images without a hurricane eye and external data.
关键词： synthetic aperture radar (SAR),hurricane inflow angle,Sentinel-1A (S-1A),Stepped Frequency Microwave Radiometer (SFMR),hurricane wind direction retrieval,CMOD5.N,rainband streaks
更新于2025-09-04 15:30:14