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

摘要OPP-0085176A.W.EngandSTAR-Light-用于北极陆地表面水文的轻型飞机上的1.4 GHz扫描薄阵列辐射计STAR-Light将使水文学家能够将陆地-大气能量和水分输送过程的曲线图模型扩展到环极地北极。在具有代表性和可访问的地点进行的北极能量平衡实验被用来开发陆面过程(LSP)模式，但从这些地点外推到北极圈变化和混合的地形将需要模型校准和验证，这只能通过从春季融化到秋季冻结的广泛区域的频繁观测才能实现。一旦校准，这些区域模型将作为大气模型的改进下限，或作为综合区域水文模型中更可靠的要素。LSP模型的核心是对土壤、植被和雪中储存的水分的估计。通过同化对土壤上层几厘米的水分的几乎每天的观测，可以显著提高这些估计的质量和模型预测的技巧。遥感水文界将1.4 GHz亮度作为这一目的的最有效观测。最近在辐射计技术、LSP/无线电亮度模式和同化辐射亮度的有效方案方面的突破，使我们走上了一条可靠的长期监测整个北极冻土带内储存的水分的数量、状态和空间分布变化的道路。这一设想的基本要素是来自卫星辐射计和经校准的北极地形LSP/R模型的数据。欧洲航天局和美国国家航空航天局都在开发用于近地轨道的1.4 GHz合成孔径辐射计。水文学家正在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，以迎接来自这些仪器的数据的出现。这些努力的重点一直是草原地形。目前还没有经过验证的北极地形LSP/R模型，尽管人们可以合理地辩称，遥感技术对北极的地球系统科学更重要。针对北极地形的成熟的LSP/R模型需要北极土壤和雪水文学家和遥感水文学家参与协作活动，并得到来自机载1.4 GHz成像辐射计的几乎每天的区域数据的支持。未来十年只有三台这样的仪器计划--两台在欧洲，另一台是NASA电子扫描薄阵列辐射计(ESTAR)的增强版，它搭载在NASA P-3-一种大型四引擎涡轮螺旋桨飞机上。P-3的高昂运行成本，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，都将极大地限制其在北极季节性和年度间调查中的使用。PI的研究小组开发了第一个紧凑型、1.4 GHz、直接采样数字辐射计(DSDR)的例子。拟议的星光仪器将使用7个1.4 GHz DSDR接收器，配置为2维合成孔径辐射计。星光将足够紧凑和坚固，可以在北极的轻型飞机或无人驾驶飞行器(UAV)上运行。设计目标是它符合超级幼崽的性能和配置限制。星光将由密歇根大学的空间物理研究实验室(SPRL)在3年内设计、制造和测试。

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.