AAF G1 and Millimeter Wavelength ARM Radar Observations and Analysis from the ACAPEX Field Campaign

Abstract:

From late January to early March of 2015, the ARM Cloud Aerosol Precipitation Experiment (ACAPEX) deployed a variety of instruments to study atmospheric rivers as they made landfall on the western United States. These atmospheric rivers are an important source of rainfall for the drought-ridden regions of California, so it is important to understand the cloud characteristics and processes that occur during the events. For this study, the KAZR zenith pointing millimeter wavelength radar aboard the Ron Brown research vessel as well as two cloud probes, namely the Two-Dimensional Stereo Probe (2DS) and High Volume Precipitation Spectrometer-3 (HVPS3), flown on the ARM Aerial Facility Gulfstream-1 (AAF G1) aircraft were used to analyze the clouds associated with the atmospheric rivers. PyDisdrometer, an open-source software, is used to calculate radar reflectivity values based on the drop size distributions observed by the cloud probes so that the aircraft data may be directly compared to the KAZR data. This research will focus on two flight days. First, a coordinated flight flown on February 5, where the G1 flew a spiral pattern over the Ron Brown while the KAZR was running will be used to examine the clouds over the ocean. This will also allow for a direct comparison between the calculated radar reflectivity from the cloud probes and the KAZR measured reflectivity. The second case was chosen to be the atmospheric river landfall event on February 6. This case will be analyzed over the ocean using the KAZR, then over the shoreline, Sacramento, and the inland mountains using the cloud probe data, as well as other instrumentations onboard the G1, such as those that measure cloud thickness and liquid water content. In this way, the changes that occur to the clouds as they move from open-ocean to land may be examined in greater detail.