The disdrometer electronics estimates the rain drop sizes using 127
different diameter sizes. The Distromet software accumulates the
number of rain drops detected in 20 different diameter sizes over 1
minute intervals. The disdrometer at BAO used the manufacture's
software. At PLT, software developed at the
NOAA Aeronomy Laboratory was used to read and store the full
127 different diameter sizes at a 10 second resolution. The
recorded 127 bin resolution data
was filtered to produce the 20 bin and 1 minute resolution data that
many researchers
use in their work. The 20 diameter and 127 diameter data sets for
PLT are provided below. Caution
must be used when using the 127 bin resolution data. The
Joss-Waldvogel
disdrometer was not designed to used with this resolution. Thus,
the 127 bin data is considered a research data product without the
endorsement
of the manufacture.
The JWD is designed to estimate the raindrop size by converting the
'momentum' of the raindrops impacting the sensor into a diameter size
assuming that the raindrops are falling at their sea level terminal
velocities. An adjustment was made to the diameter sizes recorded
by the disdrometer to account for the observations being made at 1600 m
above sea level. The details of the altitude adjustment are
provided in this PDF
document.
| Column Number | Description |
| 1 | year |
| 2 | day of year |
| 3 |
month |
| 4 |
day of month |
| 5 |
hour of day |
| 6 |
minute of hour |
| 7 |
number of drops detected in minute |
| 8 |
reflectivity, dBZ |
| 9 |
rain rate, mm/hour |
| 10 |
liquid water content, g/m^3 |
| 11 | median diameter, Do, mm |
| 12 | mean diameter, Dm, mm, (Fourth Moment / Third Moment) |
The number conctration, N(D), was estimated from the 20 diameter sizes and 1 minute accumulation observations. The format of the N(D) data is:
| Column Number | Description |
| 1 | year |
| 2 | day of year |
| 3 |
month |
| 4 |
day of month |
| 5 |
hour of day |
| 6 |
minute of hour |
| 7-27 |
number concentration, N(D) |
The number of raindrops detected at each diameter size during the 1 minute accumulation is presented in ASCII format:
| Column Number | Description |
| 1 | year |
| 2 | day of year |
| 3 |
month |
| 4 |
day of month |
| 5 |
hour of day |
| 6 |
minute of hour |
| 7-27 |
number of drops detected in the minute, m(D) |