Modelling Sea Surface Wind Vectors with Coherent Dual Polarization Synthetic Aperture Radar

使用相干双偏振合成孔径雷达模拟海面风矢量

• 批准号: RGPIN-2018-04221
• 负责人: Collins, Michael
• 金额: $ 3.13万
• 依托单位: University of Calgary
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2019
• 资助国家: 加拿大
• 起止时间: 2019-01-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=688666
• 关键词: Modelling; Sea; Surface; Wind; Vectors

Canada is a maritime nation, whose economy and general well-being is closely tied to the sea. The sea ice in Canada's Arctic continues to reach annual minima that exceed historical levels, increasing ship traffic and resource exploitation, as well as extending the iceberg season in eastern Canada. Massive cruise ships are starting to ply the waters of the Northwest Passage and Baffin Bay exposing northern communities to new economic opportunities. Yet, global warming, which has created these ice-free conditions, has also led to extreme weather, which increases the risks of maritime operations in the North.******The overall objective of this research is to improve Canada's capability of monitoring the wind field in Canada's north, including the channels between the Arctic islands, and the waters between Greenland and Newfoundland.******An imaging radar is the perfect instrument for gathering information over Canada's northern waters as it is capable of imaging night or day and in all weather, including thick clouds. Imaging radar can transmit and receive microwaves at certain polarizations, like polarizing sunglasses can block out light reflected from the water that has a certain polarization. The Canadian Space Agency is preparing to launch a new generation of imaging radar satellites, called the Radarsat Constellation Mission or RCM. These new satellites will be able to transmit one polarization, and create one image, at the same polarization that was transmitted, plus a second image at the exact opposite polarization. This is called dual-polarization.******In this research I will explore the use of dual-polarized radar images of the sea to create maps of wind speed and direction. To do this I will look at the intensity of the energy in each image, and I will combine this with the Doppler frequency in each image. The Doppler effect is the change in frequency of a wave that is received by a moving receiver. You hear this effect when a fire engine drives past you - it is a high pitched sound as it approaches, and a lower pitched sound as it drives away. As the radar approaches a patch of sea surface it is at a higher frequency, and as it flies past the frequency gets lower. This situation gets more complicated as the receiver moves, e.g. if the fire engine is driving towards you as you are riding your bike. The frequency on approach is even higher and gets even lower as the radar passes by. This effect is predictable (and different for each polarization), and is related to the movement of the sea surface, and in turn to both the wind speed and direction, which is what I will estimate.

加拿大是一个海洋国家，其经济和整体福祉与海洋息息相关。加拿大北极的海冰继续达到超过历史水平的年度最低水平，增加了船舶交通和资源开采，并延长了加拿大东部的冰山季节。大型游轮开始在西北航道和巴芬湾水域航行，使北部社区面临新的经济机会。然而，全球变暖造成了这些不结冰的条件，也导致了极端天气，这增加了北方海上作业的风险。这项研究的总体目标是提高加拿大监测加拿大北部风场的能力，包括北极岛屿之间的海峡，以及格陵兰和纽芬兰之间的水域。成像雷达是收集加拿大北部水域信息的完美工具，因为它能够在夜间或白天和所有天气，包括厚厚的云层。成像雷达可以在一定的偏振下发射和接收微波，就像偏振太阳镜可以阻挡具有一定偏振的水中反射的光一样。加拿大航天局正准备发射新一代成像雷达卫星，称为Radarsat星座任务或RCM。这些新卫星将能够发射一种偏振，并以与发射时相同的偏振创建一幅图像，再以完全相反的偏振创建第二幅图像。这被称为双极化。在这项研究中，我将探索使用双极化雷达图像来创建风速和风向地图。为此，我将查看每张图像中的能量强度，并将其与每张图像中的多普勒频率相结合。多普勒效应是由移动的接收器接收到的波的频率变化。当消防车从你身边驶过时，你会听到这种效果--当它接近时，它是一个高音，当它开走时，它是一个较低的音调。当雷达接近一块海面时，它的频率会更高，而当它飞过时，频率会变得更低。随着接收器的移动，这种情况会变得更加复杂，例如，当你骑车时消防车正向你驶来。接近时的频率更高，随着雷达的经过，频率变得更低。这种影响是可以预测的(每种极化都不同)，它与海面的运动有关，反过来又与风速和风向有关，这是我将估计的。