The Properties of Mixed Phase- and Ice Clouds in the Arctic Using a Tethered Balloon System Deployed in Support of the International Polar Year (IPY)

在下一个世纪，预计北极表面温度将以全球平均速度的两倍上升（气候小组，2007年）。 极地冰盖上的浅层低层云的作用可能非常重要，因为它们与可见光和红外波长的辐射能量的相互作用可以不同地减少或放大这种变化，净结果强烈依赖于这些云的详细微观结构（例如，其中过冷液态水与冰的相对量和颗粒尺寸）。最近的证据表明，春季和夏季云量增加，伴随着融化速度加快和相关的变薄/退缩的极地浮冰，使我们更加迫切地了解这种联系。这里支持的工作体现了史蒂文斯理工学院和SPEC公司之间的密切合作，将获得并分析北极云层微物理和辐射特性的低水平测量结果。 这些独特的详细数据将通过一个系留气球系统与挪威支持的科学计划（THORPEX-IPY）在2008年国际极地年期间在新奥勒松，位于78度N在斯瓦尔巴群岛（前斯匹茨卑尔根）群岛在8个星期的时间在春天，当广泛的低层云层覆盖和相关的表面辐射反馈是有利的。 观测将使用由SPEC开发的一个先进的气球载云微物理观测系统进行，该系统包括一个用于云粒子成像和云滴计数的仪器，一个由史蒂文斯技术研究所定制的用于监测可见光和近红外辐射能量通量的辐射计，以及获得标准气象观测套件所需的仪器。 所有这些数据都将实时遥测到地面站。 使用系留气球平台将允许云结构和辐射/热条件重复和频繁地被描绘成更接近地面的水平，并且比使用研究飞机可能的时间长得多（约24小时），并且成本低得多。 这一信息将输入一个综合辐射传输模型，该模型能够分离和量化可变云量特性对底层冰的影响。 通过与同期地面和卫星测量结果的比较，将进一步调整和改进这一模型，以准确地反映云-冰的相互作用。 这一改进模型的简化版本最终将被纳入全球尺度的卑尔根气候模型，以便利用这些结果改进对当前气候条件的诊断和更准确的长期预测。

Over the next century, Arctic surface temperatures are predicted to rise at twice the rate of the global mean (IPCC, 2007). The role of shallow low-level clouds over the polar ice sheets is potentially quite important, since their interaction with radiative energy at both visible and infrared wavelengths can variously reduce or amplify such changes, with the net outcome being strongly dependent on the detailed microstructure of these clouds (e.g., the relative amounts and particle sizes of supercooled liquid water vs. ice within them). Recent evidence of increased spring and summer cloudiness accompanied by accelerated melt rates and associated thinning/retreat of polar pack ice lends additional urgency to our improved understanding of such linkages. The work supported here, which embodies a close collaboration between Stevens Institute of Technology and SPEC Inc., will obtain and analyze low-level measurements of microphysical and radiative properties in Arctic clouds. These uniquely detailed data will be obtained via a tethered balloon system operated in conjunction with a Norwegian-supported scientific program (THORPEX-IPY) during the 2008 International Polar Year at Ny-Alesund, located at 78 deg N in the Svalbard (formerly Spitzbergen) archipelago over an eight week period during the spring, when widespread low-level cloudcover and associated surface radiative feedbacks are favored. Observations will be obtained using a sophisticated balloon-borne cloud microphysical observing system developed by SPEC, which includes an instrument for imaging cloud particles and counting cloud droplets, a radiometer custom engineered by Stevens Technical Institute for monitoring radiative energy fluxes in the visible and near-infrared, as well as instruments required to obtain standard suite of meteorological observations. All of these data will be telemetered to a ground station in real-time. Use of a tethered-balloon platform will allow cloud structure and radiative/thermal conditions to be repeatedly and frequently profiled down to levels much nearer the surface and over far longer (~24 h) continuous periods than would be possible using research aircraft, and at considerably lower cost. This information will be input into a comprehensive radiative transfer model capable of isolating and quantifying the impact of variable cloudcover properties on the underlying ice. Through comparisons with contemporaneous ground- and satellite-based measurements, this model will be further tuned and improved to accurately represent cloud-ice interactions. A simplified version of this refined model will ultimately be incorporated into the global-scale Bergen Climate Model so as to leverage these results toward improved diagnosis of current climate conditions and more accurate long-range predictions.