May 15, 2014

POINT OF CONTACT

Principle investigator:
     Kirk L. Clawson
     NOAA Air Resources Laboratory Field Research Division
     1750 Foote Dr.
     Idaho Falls, ID 83402
     Kirk.Clawson@noaa.gov
     (208) 526-2742

README.TXT - Description of Radiosonde Data Files

Experimental Procedures

Radiosonde launches were performed before and after each test period from near the 
command center. The first balloon of a test period was launched approximately 15 
minutes before the samplers were set to begin sampling the tracer plume. The second 
balloon was launched approximately 15 minutes after the end of the sampling period. 
A summary of the radiosonde launches is given listed below. All times are given in 
MDT. Data from all launches were recorded during ascent through balloon burst and 
continued through descent until the signal could no longer be acquired, except for 
the second launch of IOP5. During this launch, the battery failed in the base station 
signal receiving radio during balloon ascent and this problem was not discovered until 
it was too late to reacquire the radiosonde signal. The longest flight was 2 hours, 
18 minutes, while the shortest flight was 56 minutes. The average flight length was 
1 hour, 38 minutes.

IOP	Date	Launch	End of	Duration	High Point	Average
		Time	Ascent	(hh:mm)		hPa	m	Ascent Rate (m/s)
1	10/2/13	1503	1646	1:43		27.4	23,186	4.2
		1741	1959	2:18		20.4	24,992	3.4
2	10/5/13	1350	1530	1:40		31.6	22,255	4.3
		1607	1745	1:38		39.8	20,765	4.4

3	10/7/13	1338	1514	1:36		49.0	19,348	4.3
		1618	1750	1:32		36.4	21,194	4.7
4	10/11/13 1445	1619	1:34		36.9	21,161	4.4
		 1708	1841	1:33		40.8	20,534	4.6
5	10/18/13 1342	1534	1:52		29.3	22,512	4.1
		 1602	1658	0:56		105.4	14,531	4.3

The radiosonde system used was the GRAW model GS-H ground station (GRAW Radiosondes 
GmbH & Co. KG, Nuernberg, Germany) with GRAWMET software version 5.9.2.4, in conjunction 
with the GRAW digital radiosonde model DFM-09. A 200-gram balloon supplied the lift. The 
balloons were intentionally under-inflated to slow the balloon ascent in order to maximize 
the number of measurements in the boundary layer during balloon ascent. A target ascent 
rate of 4 m/s  was selected. An average ascent rate of 4.3 m/s was achieved, which is 
only slightly less than the minimum ascent rate of 4.6 m/s requested by the National 
Weather Service (NWS).

Quality Control

The data is provided on an as is basis. The only data available for any kind of comparison 
is the wind speed and direction data from PRO and temperature data from the RASS and that 
comparison is limited.

Data Files and Results
	
Summary graphs of the radiosonde data were produced for each ascent. These graphs are: 
1) profile data diagram, 2) thermodynamic (Stueve) diagram, 3) tephigram, 4) skew-T 
diagram, 5) emagram, 6)  altitude diagram, 7) balloon track, and 8) hodograph.

Profile data diagrams contain traces of wind speed, air temperature, relative humidity, 
air pressure, balloon altitude, and balloon rise speed plotted against time since balloon 
launch. The graph contains data from both the ascent and descent of the sonde. 

Thermodynamic or Stueve diagrams contain traces of wind speed, wind direction, air 
temperature, and relative humidity plotted as a function of geopotential height. An air 
temperature curve steeper than the dry adiabatic curve indicates a stable layer, while 
an air temperature curve that equals the dry adiabatic curve indicates a layer of neutral 
stability. 

Tephigrams contain traces of air temperature, dew point temperature, and wet bulb 
temperature on a temperature-potential temperature graph. These are used to estimate 
the thermal stability of the atmosphere. 

Skew-T diagrams show traces of air temperature and dew point temperature on a 
temperature-pressure graph. These graph produces a perpendicular angle between isotherms 
and dry adiabats. 

Emagrams show traces of air temperature and dew point temperature on a temperature-pressure 
(logarithmic scale) graph. These are a vertical representation of temperature and humidity.

Altitude diagrams show wind speed, wind direction, air temperature, relative humidity and 
pressure as a function of altitude. 

Balloon tracks show the distance and direction of the balloon over the earth’s surface. 
It also contains wind barbs plotted in two-minute intervals. Each stroke is 10 knots, while 
each ½ stroke is 5 knots wind speed. The plot contains data from both the ascent and descent 
of the sonde. 

Hodographs show the vector representation of wind motion. A new vector is plotted every 
1,000 geopotential meters. Wind barbs are also plotted on the right-hand side of the 
graph in two-minute intervals in units of knots.

Various reports were automatically generated by the GRAWMET software at the completion 
of each radiosonde flight. These reports included: 1) 20,000 ft., 2) altitude, 3) forecast, 
4) RTS, 5) SHR, 6) significant levels (according to WMO specifications), 7) standard 
levels, 8) summary, 9) upper air data table report, 10) wind report, 11) TEMP messages, 
12) PILOT messages, 13) BUFR messages, and 14) ballistic messages. These reports were 
generated in ASCII text and PDF formats. 

Four other reports that may be of additional interest were manually generated and saved 
in ASCII format. These files are called: 1) AverageLayerWinds.txt, 2) Overadiabats.txt, 
3) ProfileData.txt, and 4) RTS.txt. The AverageLayerWinds file contains averaged 
radiosonde output in approximately 100 m altitude increments for comparison with output 
from the 915 MHz wind profiling radar. The data included in this file are: 1) height AGL, 
2) time after launch, 3) pressure, 4) air temperature, 5) virtual temperature, 6) relative 
humidity, 7) absolute humidity, 8) dew point temperature, 9) wind direction, and 10) wind 
speed.  The Overadiabats file contains the altitudes at which the GRAWMET software 
calculated overadiabatic conditions during ascent of the radiosonde. The data included 
in this file are: 1) altitude range both AGL and MSL, 2) air temperature difference, 3) 
average temperature gradient, and 4) maximum temperature gradient. ProfileData.txt provides 
a number of measured and calculated variables in one second time steps. The data include: 
1) pressure, 2) air temperature, 3) relative humidity, 4) wind speed, 5) wind direction, 
6) latitude, 7) longitude, 8) altitude, 9) geopotential height, 10) dew point temperature, 
11) virtual temperature, and 12) balloon ascent rate. The RTS file contains similar 
information as the ProfileData file.

The entire collection of graphs and reports described above is provided in the data 
archive for the project. The header information in each file explains the contents. 
The data are provided as is, without the application of any additional quality controls. 
All time stamps are UTC (7 hours ahead of MST).
