Studying effects of precipitation on the bright band

The Micro Rain Radar can be used to observe the atmospheric freezing layer (bright band) to gain a greater understanding of the modifying influence (if any) of precipitation.

Typical output from the MRR showing the reflectivity in the icing zone (bright band) . . .	. . . and here showing the falling velocity
Click to expand pictures in new window

Many international organisations are involved in measuring precipitation for a variety of uses from adjustment of weather radars, flood forecasting, present weather detection, precipitation contributions to chemical or aerosol transport and development, volcano eruptions. This work is increasing the scientific communities knowledge of Drop Size Distributions (DSD) evolution with height studies as well as observation of the freezing layer also known as the 'bright band'.

Awareness of the bright band has been around for quite some time and operationally forecasters as well as the computer modelling community use this information to aid them in their work. The latest thoughts on the development of the bright band are that precipitation just below the bright band has a modifying affect on the freezing level itself and can contribute significantly to the rapid decay of the freezing level height. Previously this has been very hard or near impossible to observe operationally and especially repeatedly but now using the latest technology of the Micro Rain Radar (MRR), a newly released and unique precipitation measurement device, several users are finding this a cost effective way (prices start from £14k) at looking into this phenomenon. By using the MRR they hope to gain a greater understanding of the modifying influence (if any) of precipitation just below the bright band on the bright band itself.

Studies in the UK and USA have been running for just over a year now on this area and together with another winter seasons’ data it is hoped that some first patterns can be understood, analysed and published then integrated into operational weather models for forecasting with greater precision.

Drop Size Distributions (DSD)

Vertical profiles of drop size distribution x axis = drop diameter     y axis = height above radar colours indicate the number of drops per size interval
Light rain event	Heavy rain event

For studies into drop size distribution many users are finding the Micro Rain Radar a useful tool. The MRR is not influenced by ambient wind conditions and therefore provides far more accurate drop size distributions than typical 'point' optical disdrometers as well as additionally giving a complete vertical profile of the precipitation.

Unlike other 'normal' radars the MRR does not calculate DSD from reflectivity data but inherently measures the precipitation size and from this the terminal fall velocity can be exploited from the drop size diameter. Once this relationship has been established the accumulation rates, drop size distributions, liquid water content amounts, among other derived parameters can be found allowing a far better understanding of the development of the precipitation as it passes overhead. The MRR is able to produce 30 range heights for measurements with a spacing of between 30 m and 200 m, giving a range potential of 1 Km using a 30 m resolution and up to 6 Km using a 200m resolution. 

____________________________________________________________________

If you would like to discuss whether the Micro Rain Radar is the right tool to provide the data you require or to find out about alternatives please contact Richard McKay at wwwmet@biral.com

We hope this information has been useful - for further information please check out the links at the bottom of the MRR main page.

E.&O.E.  ©