Fine Scale 3D Wind Field Observation With a Multistatic Equatorial Atmosphere Radar

Abstract

Radar observation is widely recognized as an essential technique to study the three-dimensional dynamics of the atmosphere with a high temporal resolution. Conventional monostatic radar with a single aperture or array, however, has rather limited spatial resolution. This is because this radar can only obtain the radial component of the wind velocity, and thus it must observe at least three spatially separate target volumes to estimate the three components of the wind vector. In this paper, a multistatic radar observation technique, which uses two receiver arrays together with a high-gain rapid scanning mesosphere-stratosphere-troposphere (MST) radar, is presented. Multistatic receiver arrays obtain non-radial components of the wind velocity; hence, the technique enables us to determine 3D wind velocity at each minimum resolution volume. Consequently, it eliminates estimation error caused by horizontal inhomogeneity of the wind field and improves spatial resolution. Applying this technique, we made a series of tropospheric observations in September 2004, utilizing a newly developed digital receiver system at the Equatorial Atmosphere Radar, West Sumatra, Indonesia. Each receiver antenna is equipped with this digital receiver and recording system, which is constructed with a cost-effective ready-made digital receiver PCI board and a PC. This structure enables us to swing the receiving beam after an observation using digital beamforming techniques. First, the importance and the effectiveness of ground clutter rejection using an adaptive spatial filter, which is another advantage of digital receiver systems, is demonstrated. Then for the first time an example profile of a 3D wind velocity field with 1-km horizontal resolution at 3.8 km altitude is presented. Considering the accuracy of the multistatic radar system, the resulting wind field shows the existence of significant perturbation that previously would have been averaged in conventional monostatic radar observations.