XPOW Project Data

The data is available as a ZIP file (~ 34 MB).  The uncompressed size of the data archive is about 120 MB. We can also provide the data on a CD-ROM disk or a few other formats.  Please contact Anton Kruger

The unzipped/untarred archive contains two directories:

• “data” that contains the raw, and slightly processed data

• “products” that contains daily files for rainrate, reflectivity, and DSD

All files in the product directory are date labeled with a six-character date of the form yymmdd.  The two-digit tag at the end of all files in the product directory indicate the resolution of the data in minutes.  Additionally, the daily files residing in the data/osp directory are date labeled in a similar manner.

data/poss:  The drop size distribution data is contained in the files beginning with PD, but the coding can be cryptic, so it may be easier to simply use the daily POSS DSD files contained in the products directory.

data/jw:  The directory for each day contains the raw hourly files, as well as a daily file, into which the hourly files  have been combined.  The daily files simply contain drop counts for each bin.

data/osp:  The raw directory contains the most raw form of data.  Using the MS-DOS program LITDV.EXE, these can be converted to text files containing information about individual drops passing through the sensing area.  These files have been converted to daily files and can be found in the daily directory.  Each daily file contains two columns.  The first contains the minute at which the drop was sensed, and the second column is the drop's diameter, in mm.  The header consists of one line—the date and the number of drops recorded that day.  If one wishes to independently create daily files, the file “index.txt” in the raw directory contains information about the start and stop of data collection.

data/video: Within the monthly directories are daily subdirectories containing minute files with drop by drop information.  The file 01314.asc contains a sample header describing each of the columns found in the minute files.  Minute files are date stamped as yymmddhh.mn.  Further, each daily subdirectory also contains a daily file, with dsd, rainrate and dBZ information at 1-minute time scales.  The first column in these files is the time, the next 20 columns correspond to DSD in JW drop classes.  The last two columns are rainrate and dBZ, respectively.

products/rainrate:  These files contain 6 columns.  The first is the minute of the day, the second corresponds to POSS rainrates.  The third column contains JW rainrates, and the fourth contains rainrates for the French optical disdrometer  “Nantes.”  The fifth column is the 2DVD rainrate.  The sixth column is the algebraic mean of the three instuments.  Values of –999.0 represent missing data.  The POSS rainrate was taken directly from the POSS data file, and is based on the DSD.  Rainrates for the JW, 2DVD, and Nantes rainrates were computed using the following formula, with units of mm/hr and resolution of 1-minute:

For these calculations, the velocity-diameter relation is assumed to be:

products/reflectivity: These files contain 6 columns which correspond to the same time or instrument information as in the rainrate files.  Again, values of –999.0 represent missing data.  Units are dBZ, resolution is 1-minute.  The reflectivity was computed using the following equation:

products/dsd: The files are 21 columns by 1440 rows.  The first column contains the minute during the day, and the remaining 20 columns contain N(D_i) (m^-3 mm^-1) for each of the 20 JW bin classes.  The 34 bin POSS distribution was redistributed into the 20 bin JW distribution to more easily facilitate DSD comparisons.