The NASA Goddard Space Flight Center (GSFC) Scanning Raman Lidar (SRL) participated in the International H2O Project (IHOP), which occurred in May and June 2002 in the midwestern part of the United States. The SRL received extensive optical modifications prior to and during the IHOP campaign that added new measurement capabilities and enabled unprecedented daytime water vapor measurements by a Raman lidar system. Improvements were also realized in nighttime upper-tropospheric water vapor measurements. The other new measurements that were added to the SRL for the IHOP deployment included rotational Raman temperature, depolarization, cloud liquid water, and cirrus cloud ice water content. In this first of two parts, the details of the operational configuration of the SRL during IHOP are provided along with a description of the analysis and calibration procedures for water vapor mixing ratio, aerosol depolarization, and cirrus cloud extinction-to-backscatter ratio. For the first time, a Raman water vapor lidar calibration is performed, taking full account of the temperature sensitivity of water vapor and nitrogen Raman scattering. Part II presents case studies that permit the daytime and nighttime error statistics to be quantified.
Doppler lidar technology has advanced to the point where wind measurements can be made with confidence from space, thus filling a major gap in the global observing system.
The edge technique is a new and powerful method for measuring small frequency shifts. With the edge technique a laser is located on the steep slope of a high-resolution spectral filter, which produces large changes in transmission for small frequency shifts. A differential technique renders the frequency shift measurement insensitive to both laser and filter frequency jitter and drift. The measurement is shown to be insensitive to the laser width and shape for widths that are less than the half-width of the edge filter. The theory of the measurement is given with application to the lidar measurement of wind. The edge technique can be used to measure wind with a lidar by using either the aerosol or molecular backscattered signal. Examples of both measurements are presented. Simulations for a ground-based lidar at 1.06 microm using reasonable instrumental parameters are used to show an accuracy for the vector components of the wind that is better than 0.5 m/s from the ground to an altitude of 20 km for a 100-m vertical resolution and a 100-shot average. For a 20-m vertical resolution and a 10-shot average, simulations show an accuracy of better than 0.2 m/s in the first 2 km and better than 0.5 m/s to 5 km.
The NASA GSFC Scanning Raman Lidar (SRL) participated in the International H2O Project (IHOP)
that occurred in May and June 2002 in the midwestern part of the United States. The SRL system
configuration and methods of data analysis were described in Part I of this paper. In this second part,
comparisons of SRL water vapor measurements and those of Lidar Atmospheric Sensing Experiment
(LASE) airborne water vapor lidar and chilled-mirror radiosonde are performed. Two case studies are then
presented: one for daytime and one for nighttime. The daytime case study is of a convectively driven
boundary layer event and is used to characterize the daytime SRL water vapor random error characteristics.
The nighttime case study is of a thunderstorm-generated cirrus cloud case that is studied in its meteorological
context. Upper-tropospheric humidification due to precipitation from the cirrus cloud is quantified
as is the cirrus cloud optical depth, extinction-to-backscatter ratio, ice water content, cirrus particle size, and
both particle and volume depolarization ratios. A stability and back-trajectory analysis is performed to study
the origin of wave activity in one of the cloud layers. These unprecedented cirrus cloud measurements are
being used in a cirrus cloud modeling study
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