Synergetic use of MMCR and C-POL radars for retrievals of cloud and rainfall parameters

Poster PDF

Description

A combined radar approach for retrieving cloud and rainfall parameters in the vertical column above the TWP Darwin ARM site is suggested. This approach uses vertically pointing radar measurements from the MMCR and scanning radar measurements from the C-POL radar above Darwin. Rainfall retrieval constraints are provided by data from a surface impact disdrometer. The approach is applicable to stratiform precipitating cloud systems when a separation between the liquid hydrometeor layer, which contains rainfall and liquid water clouds, and the ice hydrometeor layer is provided by the radar bright band. Absolute C-band reflectivities and Ka-band vertical reflectivity gradients in the liquid hydrometeor layer are used for retrievals of the rain water path (RWP) and cloud liquid water path (CLWP) in this layer. Mean layer rain rate is also estimated. C-band reflectivities from C-POL are then used to estimate ice water path (IWP) in cloud regions above the melting layer. The retrieval uncertainties of CLWP and IWP for typical stratiform events are around 500-800 g/m² (for CLWP) and about 50-70% (for IWP). The CLWP retrieval uncertainties increase with rain rate. The expected uncertainties of layer mean rain rate retrievals are around 20%, which is due in part to the constrains available from disdrometer data. The applicability of the suggested remote sensing approach is illustrated by two characteristic events observed at the Darwin ARM site during the wet season of 2007. Rain rates during these events were averaging at about 2-4 mm/h with some brief periods of heavier rainfall. Typical retrieved values of CLWP were between 1 and 2 kg/m². IWP values were generally significantly higher. Future use of W-band radar at the Darwin ARM site can improve retrieval accuracies.