Upper tropospheric water vapor: A field campaign of two Raman lidars, Airborne hygrometers, and Radiosondes
Upper tropospheric water vapor: A field campaign of two Raman lidars, Airborne hygrometers, and Radiosondes
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对流层上层水蒸气：两台拉曼激光雷达、机载湿度计和无线电探空仪的现场活动
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发表时间：
1998
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通讯作者：
R. Ferrare
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作者：
S. Melfi;D. Turner;K. Evans;D. Whiteman;G. Schwemmer;R. Ferrare
大气中的水汽在辐射传输和辐射平衡过程中起着重要的作用，对理解全球变化至关重要。它是云形成的主要成分，云是最难模拟的大气过程之一，也是地球-大气环流中变化最大的组成部分。作为一种自由分子，它是最活跃的红外吸收体和发射体，因此是最重要的温室气体。水蒸气的辐射影响在大气的各个层面都很重要。尽管从地球表面到对流层顶，水分减少了几个数量级，但最近的研究表明，从辐射的角度来看，任何水平的水蒸气的小百分比变化几乎是相等的。因此，需要在各级对这一重要的大气成分进行准确和精确的测量，以评估全面的辐射影响。由于所遇到的条件一般都很恶劣（非常干燥和寒冷），因此需要改进对流层上部的测量。由于水蒸气对理解辐射传输的重要性，能源部的大气辐射测量（ARM）计划在俄克拉荷马州的云和辐射试验台（CART）站点发起了一系列测量活动，特别关注大气水蒸气。计划进行三次水汽密集观测期（水汽IOP）活动。两个水汽IOP活动已经完成：第一个IOP是在1996年秋季举行的，重点是边界层水汽测量，第二个是在1997年秋季进行的，重点是边界层湿度和对流层上部的湿度。本文介绍了第二次水汽IOP期间对流层上层水汽观测资料的相互比较。将要提供的数据包括来自以下方面的水蒸气测量结果：两个拉曼激光雷达，NASA戈达德扫描拉曼激光雷达（SRL）和CART拉曼激光雷达（CARL），在IOP活动期间发射的一些维萨拉无线电探空仪，以及北达科他州大学塞斯纳引文飞机上飞行的露点湿度计。
Water vapor in the atmosphere plays an important role in radiative transfer and the process of radiative balance so critical for understanding global change. It is the principal ingredient in cloud formation, one of the most difficult atmospheric processes to model, and the most variable component of the Earth-atmosphere albedo. And as a free molecule, it is the most active infrared absorber and emitter, thus, the most important greenhouse gas. The radiative impact of water vapor is important at all levels of the atmosphere. Even though moisture decreases by several orders-of-magnitude from the Earth's surface to the tropopause, recent research has shown that, from a radiative standpoint, a small percentage change in water vapor at any level is nearly equivalent. Therefore accurate and precise measurements of this important atmospheric constituent are needed at all levels to evaluate the full radiative impact. The need for improved measurements in the upper troposphere is particularly important because of the generally hostile (very dry and cold) conditions encountered. Because of the importance of water vapor to the understanding of radiative transfer, the Department of Energy's Atmospheric Radiation Measurements (ARM) program initiated a series of measurement campaigns at the Cloud And Radiation Testbed (CART) site in Oklahoma, especially focused on atmospheric water vapor. Three water vapor intensive observation period (water vapor IOP) campaigns were planned. Two of the water vapor IOP campaigns have been completed: the first IOP was held during the fall of 1996 with a focus on boundary layer water vapor measurements, and the second was conducted during the fall of 1997 with a focus on both boundary layer moisture e and moisture in the upper troposphere. This paper presents a review of the intercomparisons of water vapor measurements in the upper troposphere aquired during the second water vapor IOP. Data to be presented include water vapor measurements ements from: two Raman Lidars, the NASA Goddard Scanning Raman Lidar (SRL) and the CART Raman Lidar (CARL), a number of Vaisala radiosondes launched during the IOP campaign, and a dew point hygrometer flown on the University of North Dakota Cessna Citation Aircraft.