Articles | Volume 8, issue 3
Research article
04 Mar 2015
Research article |  | 04 Mar 2015

Field-deployable diode-laser-based differential absorption lidar (DIAL) for profiling water vapor

S. M. Spuler, K. S. Repasky, B. Morley, D. Moen, M. Hayman, and A. R. Nehrir

Abstract. A field-deployable water vapor profiling instrument that builds on the foundation of the preceding generations of diode-laser-based differential absorption lidar (DIAL) laboratory prototypes was constructed and tested. Significant advances are discussed, including a unique shared telescope design that allows expansion of the outgoing beam for eye-safe operation with optomechanical and thermal stability; multistage optical filtering enabling measurement during daytime bright-cloud conditions; rapid spectral switching between the online and offline wavelengths enabling measurements during changing atmospheric conditions; and enhanced performance at lower ranges by the introduction of a new filter design and the addition of a wide field-of-view channel. Performance modeling, testing, and intercomparisons are performed and discussed. In general, the instrument has a 150 m range resolution with a 10 min temporal resolution; 1 min temporal resolution in the lowest 2 km of the atmosphere is demonstrated. The instrument is shown capable of autonomous long-term field operation – 50 days with a > 95% uptime – under a broad set of atmospheric conditions and potentially forms the basis for a ground-based network of eye-safe autonomous instruments needed for the atmospheric sciences research and forecasting communities.

Short summary
A water vapor lidar has been designed and tested which has the potential to enable a national-scale network. The system is low-maintenance, low-cost, eye-safe, and provides continuous profiles of water vapor with complete coverage, including periods of daytime bright clouds, from 300m above ground level to 4km with 150m nominal vertical resolution and 1 min temporal resolution. The sensor may be useful in improving our understanding of the distribution of atmospheric water vapor.