3dB thickness of bright band

Radar observations of the melting layer of precipitation have been made since the dawn of radar meteorology [1]. It has been known since then that the melting of precipitation is often associated with an enhancement of the reflectivity of weather targets. The primary cause of the enhancement is a rapid increase in the dielectric constant of hydrometeors at the top of the melting layer followed by an increase of the velocities of melting snowflakes toward the end of the melting process [2]. The radar bright band results mostly from melting of snowflakes as they fall through the 0 degrees C isotherm. As the ice is gradually transformed to liquid, the refractive index and, hence, the backscattering cross section increase, and the radar echo intensity increases to a maximum at approximate to 200 m below the 0 degrees C isotherm [3]. The decrease of echo intensity below the bright band level is mostly the result of decreases of particle concentration caused by increases of terminal velocity as the particles melt. 2A23 data provides information about the height of bright band (HBB) as well as the height of freezing. HBB is generally close to the height of freezing (usually within 2 km). In general, the bright band height is obviously linked with the height of the 0 degrees C isotherm in the atmosphere and consequently dependent on the time of the year and on the climate (and hence the location). Therefore, it is very important to develop global maps of height of bright band and height of freezing as monthly maps. HBB is very important in the case of stratiform, while the freezing height is important in convective cases. In this paper, 3dB thickness of BB is developed and examined over ocean and land by using data from TRMM PR satellite.