Water vapor tomography within the planetary boundary layer using

A network of 24 single frequency GPS stations has been installed across a 40 square kilometer area in the United States Southern Great Plains region. Slant water (SW) observations, the integrated amount of water vapor between a transmitting GPS satellite and a receiving ground based GPS station, from all 24 stations are combined with a vertical profile of water vapor from a Raman Lidar to produce a four dimensional representation of water vapor density throughout the planetary boundary layer. The GPS and lidar observations are nearly orthogonal measurements in determining the water vapor state. The GPS provides the horizontal and small-scale vertical information while the lidar helps to constrain the vertical structure in the column. The water vapor field is estimated using a 1-kilometer horizontal grid and a 500-meter vertical grid. A extended sequential process filter is used to update the solution with a five-minute time step. Figure 1: Map of the central United States with GPS stations used for atmospheric sensing shown as blue circles. The red dashed box outlines the ARM SGP area. The central facility is shown as the red star, and is the location of the tomography network. 2