Examples of data

Ground-based overview

The figure below illustrates the timeseries of W-band radar reflectivity during the timeframe of the campaign when the flights of the ATR-42 took place. Below is the timeseries of temperature at the ground level, and the bottom panel shows the types of hydrometeors captured by the MASC also near the ground level (time steps where temperature exceeds +2°C are discarded). The apparent melting proportion estimated from MASC images fluctuates rather well with the measured ground temperatures.

The figure reflects the variability of the precipitation events recorded during the flights: with both cold and warmer temperatures, deep and shallow clouds and so on.

Overview of the observation period 22/01-31/01. Panel a: time-height structure of WProf reflectivity. Panel b: average hourly temperature at ground level (only during precipitation) color coded for positive and negative temperatures; bar plot (right y-axis) shows hourly precipitation (source: MeteoSwiss). Panel c: time evolution of hydrometeor types recorded by the MASC near ground level and average proportion of particles showing melting morphology (MASC data averaged over 1~h consecutive intervals). Only hourly time intervals with at least 5 particles recorded.

Airborne in-situ measurements

The atmospheric conditions sampled during each flight are summarized in the table below:

Flight reference, date and time (UTC)Number of legsAltitude of legs (min / max, masl)Temperature range (min / max, °C)
F04 – 22/01 13:40 – 17:20181310 / 3214-8.1 / +2.8
F05 – 23/01 12:30 – 16:30221238 / 2706-12.5 / +1.7
F06 – 27/01 13:30 – 17:00181244 / 3329-9.1 / +0.47
F07 – 28/01 08:50 – 12:05141811 / 3300-9.0 / +2.3
F08 – 30/01 10:30 – 15:30281511 / 3660-9.3 / +1.6
Summary of flight conditions. Time indicates take-off and landing.

In the figure below are shown some summary statistics for each flight, with the violin plots of total water content (from the CVI) and median mass diameter (MMD) derived from 2D-S and PIP measurements. The hydrometeor classification from the PIP imager was run on all flights: the dominant hydrometeor types in the size range (2 mm to 6.4 mm)are aggregates (fragile: 33%, then rimed: 28%), followed by columnar crystals and graupel.

a) Violin plots of the TWC and MMD for the different flights. b) Hydrometeor classification from PIP images (size range: 2-6.4mm), all flights merged. FA: Fragile Aggregates; RA: Rimed Aggregates, GR: Graupel, CBC: Combinations of Bullets and Columns, HC: Hexagonal planar Crystals, CC: Columnar Crystals.