Marine boundary layer drizzle properties and their impact on cloud property retrieval

[摘要] In this study, we retrieve and document drizzle properties, and investigatethe impact of drizzle on cloud property retrieval in Dong et al. (2014a)from ground-based measurements at the ARM Azores facility from June 2009 toDecember 2010. For the selected cloud and drizzle samples, the drizzleoccurrence is 42.6 %, with a maximum of 55.8 % in winter and a minimum of35.6 % in summer. The annual means of drizzle liquid water pathLWP_d, effective radius r_d,and number concentration N_d for the rain(virga) samples are 4.73 (1.25) g m⁻², 61.5 (36.4) μm, and 0.38(0.79) cm⁻³. The seasonal mean LWP_d values are less than 3 % of the LWP valuesretrieved by the microwave radiometer (MWR). The annual mean differences in cloud-dropleteffective radius with and without drizzle are 0.75 and 2.35 %,respectively, for the virga and rain samples. Therefore, we conclude thatthe impact of drizzle below the cloud base on cloud property retrieval isinsignificant for a solar-transmission-based method, but significant for anyretrievals using radar reflectivity.

[学科分类] 几何与拓扑