Joint EOL/RAL seminar presented by Dr. J. Vivekanandan (Vivek), Manager, EOL Remote Sensing Facility
Measurements of cloud liquid properties are important in a wide range of disciplines including numerical weather prediction, climate change and in-flight aircraft icing. Depending on their size, liquid droplets are classified into three categories: cloud droplets, drizzle, and rain drops. By definition, cloud droplet size is less than 50 mu, drizzle size is between 50 and 500 mu, and droplets greater than 500 mu belong to the raindrop category. Cloud liquid water contents (LWC) are commonly below 0.1 – 0.2 g m-3, but have been measured at greater than 1 gm-3 over distances of several kilometers. Millimeter wave radar and satellite observations show potential for estimating LWC and droplet size.
In the case of spherical hydrometeors, such as cloud droplets, the utility of polarimetric measurements to estimate LWC and droplet size is limited. A dual-wavelength (transmits radiation at mm and cm wavelengths) radar method that makes use of absorption and reflectivity is more attractive for estimating LWC and droplet size. Transmitted radiation at mm wavelength is measurably attenuated by liquid, but not at cm wavelength. Radar is capable of mapping range resolved measurements, but its spatial coverage is limited. On the other hand, microwave satellite observations are suitable for estimating cloud microphysics both over land and ocean.
Radar and satellite-based methods for estimating cloud microphysical properties are presented. However, the verification of estimated quantities using remote observations is confounded due to a lack of in situ observations. Coincident ground-based microwave radiometer-based estimates are used to verify both radar and satellite-based cloud liquid properties.
Friday, March 17 at 10:30am in FL2-1022.
View the complete presentation in PowerPoint |
