A Rapid Response Instrument for In Situ Measurement of Atmospheric Water Vapor

测量水蒸气浓度或湿度在大气研究的许多领域都很重要。大多数现有仪器对高海拔或寒冷地区的测量或对表层通量的测量没有足够的灵敏度或时间响应。本研究的目的是利用液氮冷却铅盐二极管激光器，研究一种用于快速响应测量水蒸气的高分辨率红外吸收传感器的开发。在这个SBIR项目的第一阶段，一个具有优异对准稳定性的多通道吸收池设计被证明可以应用于水蒸气测量。确定了一组吸收线，可用于实现非常宽的动态范围，足以适应对流层或平流层下层所有预期条件下的湿度测量。第一阶段对这些线路的综合线强度进行了精确测量。第二阶段SBIR研究的主要目标是研究使用红外光纤简化仪器设计的方法，并通过使用双光束方法提高测量精度。将装配一个湿度传感器原型，用于实验室和当地现场测试。这些测试将包括灵敏度、准确性和时间响应的详细评估，包括与大气或气象研究中用于测量水蒸气的其他仪器的相互比较。

Measurement of water vapor concentration or humidity is important in many areas of atmospheric research. Most existing instrumentation does not have adequate sensitivity or time response for measurements at high altitudes or in cold regions, or for flux measurements in the surface layer. The purpose of this research is to study the development of a high resolution infrared absorption sensor for fast-response measurement of water vapor, utilizing a liquid nitrogen-cooled lead-salt diode laser. In Phase I of this SBIR program, a multiple pass absorption cell design which has excellent alignment stability was demonstrated for application to water vapor measurements. A set of absorption lines was identified which can be used to achieve a very wide dynamic range sufficient to accommodate measurements of humidity under all expected conditions in the troposphere or lower stratosphere. Accurate measurements of the integrated line strengths for these lines were made in Phase I. The major objectives of the Phase II SBIR research are to study methods for simplifying the instrument design using infrared fiber optics and to enhance measurement accuracy by using a dual-beam method. A prototype humidity sensor will be assembled for laboratory and local field tests. These tests will include detailed evaluations of sensitivity, accuracy, and time response, including intercomparison with other instrumentation used for water vapor measurements in atmospheric or meteorological research.