Analysis of Vertical Profiles of Precipitable Liquid Water Content in a Tropical Climate Using Micro Rain Radar

Abstract

In this paper, some distinctive features of the vertical profile of precipitable liquid water content (LWC) with considerable respect to rain rates (R) and radar reflectivity (Z) obtained in a tropical location are presented. Assessment of LWC allows applications in the specific area of flight icing severity, aviation safety as well as signals traversing through the atmosphere. The parameters were typically measured using vertically-pointing Micro Rain Radar (MRR) over a period of 2 years (2011-2012) at Akure, a tropical location of Nigeria. The radar scanned at every 10 seconds and integrated over one minute samples to reduce event logging error associated with the instrument. The vertical profile of the LWC typically reveals a prominent seasonal variation. However, majority of the LWC profiles has low LWC, less than 0.1 gm −3 while the maximum observed LWC is about 3.18 gm −3. A strong like hood relation was observed between the melting layer height and the LWC, with the LWC reaches peak at the considerable height of about 4160 m which coincides precisely with the freezing height level (rain height of ~4520 m) of the study location. Good correlation was also observed between the LWC and R in most of the heights considered. The results obtained will assist system engineers to assess the level of absorption, reflection and attenuation of electromagnetic signals as a result of precipitable LWC along the transmitting paths. The novelty of the present work is in the area of linking LWC and Z as against usual relation between Z and R.

Comparative Study of Cloud Liquid Water and Rain Liquid Water Obtained From Microwave Radiometer and Micro Rain Radar Observations Over Central China During the Monsoon

“…Thickness of clouds should be larger than 2.5 km to ensure at least 10 points in the CLWC profile because of the lowest vertical resolution of 250 m. 3. Events with a rain rate over 12 mm/h is not used because deep convection can cause erroneous values for the LWC in the MWR and MRR measurements (Calheiros & Machado, 2014;Ojo et al, 2019). 4.…”

“…However, to avoid the impact of noise on the terminal points of profile, only the profiles from 0.2 to 3.0 km are used in this study. MRR‐derived drop sizes are from 0.246 to 5.03 mm, which should be recognized as rain droplet because cloud droplets during weak precipitation have a diameter below 0.1 mm (Ojo et al, 2019). RLWC is a product of the total volume of all droplets with the density of water, divided by the scattering volume.…”

“…Measurements from polar-orbiting satellite, such as Global Precipitation Measurement (GPM), can give spatial statistics for precipitation, but the ground track repeat time is several days (Hayden & Liu, 2018) and it is difficult to cover the microphysical profiles of a whole rainfall process at a fixed location. Micro rain radar (MRR) has the ability of measuring vertical drop size distribution and can also calculate the vertical profile of RLW; MRRs therefore provide a way to study properties of RLWC and CLWC (Ojo et al, 2019).…”

“…The LWC is also a crucial parameter in numerical models, and the CLWC is the main source of water for precipitation. Therefore, understanding the variation characteristics in CLWC and RLWC and their transformation during rainfall process will help to improve the representation of clouds and the prediction of precipitation by numerical models (Korolev et al, 2007; Lee et al, 2010; Ojo et al, 2019).…”

“…The size distribution of droplets is an important microphysical parameter of precipitation, and RLWC, which is a fundamental parameter and essential for many applications, can be estimated from this parameter (Ojo et al, 2019). Drop size distribution is always measured by ground‐based disdrometer, and only information of precipitation on the ground can be derived.…”