STAR-Light - A 1.4 GHz Scanning Thinned Array Radiometer for use on light aircraft in arctic land-surface hydrology

摘要-0085176A.W.英格兰STAR-Light--北极陆面水文轻型飞机上使用的1.4 GHz扫描稀疏阵列辐射计STAR-Light将使水文学家能够将陆-气能量和水分输送过程的绘图模型扩展到北极圈。北极能量平衡实验的网站，都是有代表性的和可访问的是用来开发陆面过程（LSP）模型，但从这些网站外推到环极北极的变化和混合地形将需要模型校准和验证，可以实现只有在广泛的地区，从春季解冻和秋季冻结结束频繁的观测。这些区域模型一旦校准，将作为改进的大气模型下边界或作为综合区域水文模型的更可靠的要素。LSP模型的核心是对土壤、植被和雪中储存的水分的估计。这些估计的质量和模型预测的技巧可以通过吸收几乎每天观测的土壤上层几厘米的水分来显著提高。遥感水文界已将1.4 GHz亮度作为这方面最有效的观测。最近在辐射计技术，在LSP/Radiobrightness模型，并在有效的计划吸收radiobrightness的突破，使我们对整个北极苔原内储存的水分的量，状态和空间分布的变化进行可靠的长期监测。这一设想的基本要素是来自卫星辐射计的数据和北极地形的校准LSP/R模型。欧洲航天局和美国航天局都在为低地球轨道开发1.4 GHz合成孔径辐射计。水文学家正在为这些仪器提供的数据做准备，开展广泛的实地活动，以开发和校准LSP/R模型，并验证同化卫星数据的方案。这些努力的重点是草原地形。北极地形没有经过验证的LSP/R模型，尽管人们可以合理地认为遥感技术对北极的地球系统科学更为重要。北极地形的成熟LSP/R模型需要北极土壤和雪水文学家以及遥感水文学家的协作活动，这些活动由机载1.4 GHz成像辐射计提供的近每日区域数据支持。未来十年计划只安装三台这样的仪器--两台在欧洲，另一台是美国宇航局电子扫描薄阵列辐射计（ESTAR）的增强版，该辐射计搭载在美国宇航局P-3大型4引擎涡轮螺旋桨飞机上。P-3的高运行成本、P-3上仪器的相互冲突的时间表以及NASA许多大型野外活动对ESTAR数据的需求将大大限制其在北极季节性和跨年度调查中的使用。PI的研究小组已经开发出第一个紧凑的1.4 GHz直接采样数字辐射计（DSDR）。拟议的STAR-Light仪器将使用7个1.4 GHz DSDR接收器，配置为二维合成孔径辐射计。STAR-Light将足够紧凑和坚固，可以在北极地区的轻型飞机或无人驾驶飞行器（UAV）上运行。一个设计目标是，它适合的性能和配置限制的超级幼崽。STAR-Light将由密歇根大学的空间物理研究实验室（SPRL）设计、制造和测试，为期3年。

AbstractOPP-0085176A.W. EnglandSTAR-Light - A 1.4 GHz Scanning Thinned Array Radiometer for use on light aircraft in arctic land-surface hydrologySTAR-Light will enable hydrologists to extend plot models of land-atmosphere energy and moisture transport processes to the circumpolar Arctic. Arctic energy balance experiments at sites that are both representative and accessible are used to develop Land-Surface Process (LSP) models, but extrapolating from these sites to the varying and mixed terrains of the circumpolar Arctic will require model calibration and validation that can be achieved only with frequent observations over broad regions beginning with spring thawing and ending with fall freezing. Once calibrated, these regional models will then serve either as improved lower boundaries of atmospheric models or as more reliable elements of integrated regional hydrology models. At the heart of the LSP model are estimates of moisture stored in soil, vegetation, and snow. The quality of these estimates and the skill of model predictions can be significantly improved by assimilating near-daily observations of the moisture in the upper few centimeters of soil. The remote sensing hydrology community has converged upon 1.4 GHz brightness as the most effective observation for this purpose. Recent breakthroughs in radiometer technology, in LSP/Radiobrightness models, and in efficient schemes for assimilating radiobrightness have placed us on a path toward reliable long-term monitoring of changes in the amount, state, and spatial distribution of moisture stored within tundra throughout the Arctic. Essential elements of this vision are data from satellite radiometers and calibrated LSP/R models for arctic terrains. Both the European Space Agency and NASA are developing 1.4 GHz synthetic aperture radiometers for low Earth orbit. Hydrologists are preparing for the advent of data from these instruments with extensive field campaigns to develop and calibrate LSP/R models, and to validate schemes for assimilating satellite data. The focus of these efforts has been prairie terrains. There are no proven LSP/R models for arctic terrains even though one could reasonably argue that remote sensing technologies are more vital to Earth system science in the Arctic. Mature LSP/R models for arctic terrains require collaborative campaigns involving arctic soil and snow hydrologists and remote sensing hydrologists supported by near-daily regional data from an airborne 1.4 GHz imaging radiometer. Only three such instruments are planned for the next decade -two in Europe and an enhanced version of NASA's Electronically Scanned Thinned Array Radiometer (ESTAR) which flies on the NASA P-3 -a large, 4-engine turboprop aircraft. The high operating costs of the P-3, the conflicting schedules of instruments on the P-3, and the demand for ESTAR data in NASA's many large field campaigns will greatly limit its use in seasonal and inter-annual investigations in the Arctic. The PI's research group has developed the first example of a compact, 1.4 GHz, Direct Sampling Digital Radiometer (DSDR). The proposed STAR-Light instrument will use seven 1.4 GHz DSDR receivers configured as a 2-dimensional synthetic aperture radiometer. STAR-Light will be sufficiently compact and robust to operate in the Arctic on a light aircraft or on an Uninhabited Aerial Vehicle (UAV). A design goal is that it fit within the performance and configuration limitations of a Super Cub. STAR-Light will be designed, fabricated, and tested over a 3-year period by the Space Physics Research Laboratory (SPRL) at the University of Michigan.