National Radio Astronomy Observatory
Site Studies

Radiosonde Campaign

Balloon LaunchRadiotheodolite
Balloon launch and radiotheodolite equipment. Photos: A. Otárola, 1998 October

The Chajnantor radiosonde campaign is a collaborative effort of the US/ European ALMA project, Cornell University, the Smithsonian Astrophysical Observatory Submillimeter Receiver Lab, and the LMSA project. Flights from Chajnantor began in 1998 October.

Flight notes, ESO page, Cornell page, LMSA page

Equipment

The campaign uses two AIR 5A radiotheodolites. Through 2001 May, AIR 5A sondes were used exclusively. Vaisala acquired AIR in 1999 and discontinued the 5A sondes in 2000. The radiothodolites were upgraded in 2001 to work with Vaisala RS80 sondes.

Specifications: radiotheodolite, AIR 5A Sondes, Vaisala RS80 Sondes

Flight Data

2002

Flight UT Launch Date* & Data hmax [m] Analysis Sonde Type & Serial Number Comments
NRAO ESO
PWV [mm] plots PWV [mm] plots
290 November 3 15h 19536 RS80-67: Wind Speed in knots. Duplicate flight number. (SR)

2001

Flight UT Launch Date* & Data hmax [m] Analysis Sonde Type & Serial Number Comments
NRAO ESO
PWV [mm] plots PWV [mm] plots
290 December 13 18h 20398 ps.gz RS80-67: 131457701 Small problem at 14637 m. Wind almost to top. Narrow neck balloon. (BB)
289 December 13 13h 19903 ps.gz RS80-67: 131457708 Small problem at 14422 m. Wind almost to top. Narrow neck balloon. (BB)
288 December 12 19h 16039 ps.gz RS80-67: 131457700 No apparent problems, but had a somewhat odd descent (it was just extremely long). Can't recall balloon neck. (BB)
287 December 12 13h 14310 ps.gz RS80-67: 131457709 Didn't go so high. Fat neck balloon. (BB)
286 December 11 19h 14170 ps.gz RS80-67: 131457803 Small problems at 10908 m, 11687 m, 13068 m, 13368 m, & 13740 m. Very strange descent. (BB)
285 December 11 14h 19271 ps.gz RS80-67: 131457812 Small problem at 12746 m. Also an oddity with RH, where for short intervals, there is a large increase in RH. Wind out at 18.9 km. (BB)
283 December 10 19h 15850 ps.gz RS80-66: 048336254 Same problem as 01120916; the RH went to 1% in 3 altitude ranges. Wind to top. Fat neck balloon. (BB) 
282 December 10 16h 20712 ps.gz 5A:  Wind out at 20.1 km. (BB)
281 December 10 13h 20510 ps.gz 5A: 80110143C49 Wind out at 20.1 km. (BB)
280 December 9 19h 7745 ps.gz 5A: 80110413B29 Weirdness at low altitudes (right at the surface) - altitudes go: 5000, 5072, 5032, 5032, 5027, 5030, 5035. After that, they seem OK, but sonde didn't go very high. (BB)
279 December 9 13h 23882 ? ps.gz RS80-66: 048336249 Weirdness. Altitudes are odd at first - the order goes: 5000, 4801, 4926, 4945, 4983, 5000, 5015. The data go up to 46012 m (!), but the tempearature and dew point remain relatively unchanged above 22622 m and really don't change at all above 23895 m. Also the RH goes to 1% at 14986 m and stays there (at 1.00%) until 21540 m. (BB)
278 December 9 13h 21229 ps.gz 5A: 80110413C10 Wind out at 20.8 km. (BB)
277 December 8 18h 20217 ps.gz 5A: 80110413B37 Wind out at 19.9 km. (BB)
276 December 8 14h 19280 ps.gz 5A: 80110413B32 Wind out at 18.9 km. (BB)
275 December 7 19h 21206 ps.gz 5A: 80110413B43 Big problem at 6375 m. Wind speed and direction out at 12.8 km, back at 16.8 km, out again at 20.8 km. (BB)
272 October 31 21h 7100 RS80-67: 131457714 Tucson trial balloon; slow ascent; signal weak above 7100 m (SR)
271 October 23 22h 9690? RS80-66: 118332741 Tucson trial balloon; wind speed in knots; temperature and humidity failed at 5956 m (SR)
270 October 23 21h 1183 RS80-66: 118332746 Tucson trial balloon; wind speed in knots; premature balloon deflation (SR)
268 May 5 18h 16482 ps.gz 5A: 80110413B41
266 May 5 16h 21841 ps.gz 5.43 gif 1, gif 2 5A: 80012617B58
265 May 5 14h 18092 ps.gz 5.54 gif 1, gif 2 5A: 80012617C58
264 May 4 23h 15434 ps.gz 4.15 gif 1, gif 2 5A: 80012617C34
263 May 4 18h 19142 ps.gz 2.06 gif 1, gif 2 5A: 80012617B62
262 May 4 14h 21025 ps.gz 1.36 gif 1, gif 2 5A: 80012515B43
261 May 4 0h 14899 ps.gz 1.83 gif 1, gif 2 5A: 80012617B40
260 May 3 18h 16996 ps.gz 1.81 gif 1, gif 2 5A: 80012617B61
259 May 3 14h 15170 ps.gz gif 1, gif 2 5A: 80012515C52
258 May 3 0h 14716 ps.gz gif 1, gif 2 5A: 80012515C62
257 May 2 19h 13615 ps.gz gif 1, gif 2 5A: 80012617C44
255 May 2 14h 9064 ps.gz gif 1, gif 2 5A: 80012617B39
253 May 1 23h 16247 ps.gz gif 1, gif 2 5A: 80012617C52
252 May 1 19h 18719 ps.gz gif 1, gif 2 5A: 80012617B25
251 May 1 14h 17738 ps.gz gif 1, gif 2 5A: 80012617C60
250 May 1 0h 16423 ps.gz gif 1, gif 2 5A: 80012515B29
249 April 30 18h 19194 ps.gz gif 1, gif 2 5A: 80012515B33
248 April 30 14h 19432 ps.gz gif 1, gif 2 5A: 80012617B16 Some wind dropouts at 13-15 km. (BB)
247 April 30 0h 13153 ps.gz gif 1, gif 2 5A: 80012617C53 Major problem around 7250 m. Problem around 9900 m. Major problem around 9950 m. More problems above that. No wind above 7000 m. (BB).
246 April 29 19h 6527 ps.gz gif 1, gif 2 5A: 80012617C57
245 April 29 14h 12965 ps.gz gif 1, gif 2 5A: 80012515B28
244 April 29 0h 17331 ps.gz gif 1, gif 2 5A: 80012617C61 Wind spotty and none above 11500 m. (BB)
243 April 28 19h 13179 ps.gz gif 1, gif 2 5A: 80012515C17
241 April 28 15h 19813 ps.gz gif 1, gif 2 5A: 80012617C36
240 April 27 18h 20909 ps.gz gif 1, gif 2 5A: 80012617C19
239 April 27 14h 21950 ps.gz gif 1, gif 2 5A: 80012814A33
238 April 27 0h 6891 ps.gz gif 1, gif 2 5A: 80012814B26
237 April 26 19h 20608 ps.gz gif 1, gif 2 5A: 80012515C49
236 April 26 14h 19255 ps.gz gif 1, gif 2 5A: 80012617B59
235 April 26 2h 14027 ps.gz gif 1, gif 2 5A: 80012617C33
232 April 25 18h 11763 ps.gz gif 1, gif 2 5A: 80012515A42
230 April 25 13h 18921 ps.gz gif 1, gif 2 5A: 80012814B14
229 April 24 19h 15942 ps.gz gif 1, gif 2 5A: 80012515A06 Minor problem at 6593 m. No wind after 8000 m. (BB)
228 April 11 9h 17300 ps.gz gif 1, gif 2 5A: 80012814B24
227 April 11 7h 18631 ps.gz gif 1, gif 2 5A: 80012814A40
226 April 11 6h 14793 ps.gz gif 1, gif 2 5A: 80012515A24 Tiny problem at 8805 m. Relatively low burst. (BB)
225 April 11 4h 18105 ps.gz gif 1, gif 2 5A: 80012515A04 Seems a nice flight, but there is something very odd about the dewpoint (and hence the humidity and water vapor partial pressure). From about 12 km upward, the RH goes up rapidly until it saturates at 100% around 16.5 km. Hard to believe the numbers for this flight because of that. (BB)
224 April 11 3h 17947 ps.gz gif 1, gif 2 5A: 80012515A01 Wind data spotty above 14000 m. (BB)
223 April 11 1h 18152 ps.gz gif 1, gif 2 5A: 80012814A29
222 April 10 8h 19550 ps.gz gif 1, gif 2 5A: 80012515A38
221 April 10 6h 16018 ps.gz gif 1, gif 2 5A: 80012515A33 No wind after 12000 m. (BB)
220 April 10 3h 17375 ps.gz gif 1, gif 2 5A: 80012515A02
219 April 10 1h 19344 ps.gz gif 1, gif 2 5A: 80012617C17
217 April 9 5h 17350 ps.gz gif 1, gif 2 5A: 80012515A35
216 April 9 3h 18133 ps.gz gif 1, gif 2 5A: 80012515A39 Don't believe altitudes above 18133 m. (SR) No wind from 12500 to 17000 m? Temp & d.p. measurements got stuck at 18133 m, causing crazy altitudes. (BB)
214 April 9 1h 17479 ps.gz gif 1, gif 2 5A: 80012814A08
213 April 6 9h 11216 ps.gz gif 1, gif 2 5A: 80012515A37 No wind above 10000 m and spotty below that? Premature burst. (BB)
212 April 6 8h 12112 ps.gz gif 1, gif 2 5A: 80010406D29 No wind above 10000 m and spotty below that? Premature burst. PWV too low. (BB)
211 April 6 5h 14572 ps.gz gif 1, gif 2 5A: 99120918D49 No wind above 10000 m? Premature burst. Unbelievably low PWV compared to the launches around it.(BB)
210 April 5 8h 17836 ps.gz gif 1, gif 2 5A: 99120918D48 No wind after 12000 m and spotty before that? (BB)
209 April 5 7h 16310 ps.gz gif 1, gif 2 5A: 80012515A25 No wind after 12000 m and spotty before that. (BB)
201 April 4 5h 17774 ps.gz gif 1, gif 2 5A: 80012814A43
200 April 4 3h 17656 ps.gz 3.74 gif 1, gif 2 5A: 99120918B52
199 March 31 3h 16594 ps.gz 2.43 gif 1, gif 2 5A: 80012814B27 Big problems around 7375 m. Lasted until altitude came back up to 7375 m. No wind after ~6000 m. Artificial termination maybe? (BB)

2000

Flight UT Launch Date* & Data hmax [m] Analysis Type 5A Sonde Serial Number Comments
NRAO ESO
PWV [mm] plots PWV [mm] plots
196 December 17 13h 20167 2.43 ps.gz 2.54 gif 1, gif 2 99120918D50
195 December 16 18h 20684 1.29 ps.gz 1.33 gif 1, gif 2 99120918B63
194 December 16 15h 21319 1.90 ps.gz 2.00 gif 1, gif 2 99120918D43 Single handed launch. (BB)
193 December 16 14h 20063 1.29 ps.gz 1.34 gif 1, gif 2 99120918B58
192 December 15 18h 19815 0.59 ps.gz 99020316B53 No windspeed above 10.5 km. (BB)
191 December 15 14h 20685 1.09 ps.gz 1.18 gif 1, gif 2 99120918D04 No windspeed above 13 km. (BB)
189 December 14 18h 17221 0.99 ps.gz 1.05 gif 1, gif 2 99120118D09 No windspeed above 8.5 km. (BB)
188 December 14 14h 19042 0.88 ps.gz 0.90 gif 1, gif 2 99120918D07 No windspeed above 8.5 km. (BB)
187 December 13 18h 19326 1.23 ps.gz 1.32 gif 1, gif 2 Tiny problem near 12.3 km. (BB)
184 December 13 16h 21034 1.17 ps.gz 1.26 gif 1, gif 2 99120918B61 Tiny problem near 19 km. Windspeed spotty from 13 to 17 km. (BB)
181 December 13 13h 99120918D39
180 December 12 16h 20373 4.53 ps.gz 4.97 gif 1, gif 2 99120918B59 Help from visitors (Canizares and B.2 Millard). (BB)
179 August 22 15h 18567 1.24 ps.gz 1.36 gif 1, gif 2 99020316D02 Wind speed out around 12.3 km. (BB)
178 August 6 3h 14192 0.70 ps.gz 0.75 gif 1, gif 2 9902031CB54 or 99020316B54? (SR)
177 August 4 11h 13123 0.81 ps.gz 0.87 gif 1, gif 2 99120918D44 Short flight. (BB)
176 August 3 22h 15458 0.63 ps.gz 0.72 gif 1, gif 2 99020316C43 Wind speed out around 8.8 km. (BB)
175 August 3 13h 18001 0.27 ps.gz 0.32 gif 1, gif 2 99120918D06 Wind speed out around 7.5 km. Minor problem around 9750 m. (BB)
174 August 2 9h 9063 0.27 ps.gz 0.30 gif 1, gif 2 99120918D56 Short flight. (BB)
172 August 1 9h 10005 0.26 ps.gz 0.28 gif 1, gif 2 99120918B53 Short flight. (BB)
171 July 31 18h 15173 0.37 ps.gz 99120918B49
170 July 31 17h gif 1, gif 2 99120918D14 Useless flight. Altitudes incorrect (start around 16.5 km). Only a few entries. (BB)
169 July 31 9h 13009 0.38 ps.gz 0.42 gif 1, gif 2 99023116C19 Short flight. (BB)
168 July 30 18h 16500 0.78 ps.gz 0.89 gif 1, gif 2 99120918B55 Minor problems. (BB)
167 July 30 9h 12529 1.15 ps.gz 1.34 gif 1, gif 2 99023116C15 Short flight. Wind speed out around 10 km. (BB)
166 July 29 10h 11483 1.12 ps.gz 1.31 gif 1, gif 2 99020316C40 Short flight. Some Az & El 9999's and wind speed 999's near surface. Wind speed out around 8.5 km. (BB)
164 July 28 18h 11803 1.02 ps.gz 1.14 gif 1, gif 2 99020316C09 Short flight. Problems at 8250 m. (BB)
161 July 28 4h 10002 0.83 ps.gz 0.94 gif 1, gif 2 99020316C00 Short flight. Some wind speed drop outs. (BB)
159 July 26 17h 19637 1.35 ps.gz 1.58 gif 1, gif 2 99020316C39
155 July 25 18h 19548 0.73 ps.gz 0.78 gif 1, gif 2 99020316B33
154 July 25 4h 14489 0.63 ps.gz 0.70 gif 1, gif 2 99020316C17
150 July 23 2h 12804 0.65 ps.gz 0.75 gif 1, gif 2 80012814A28? Serial number uncertain; logbook inconsistent. (SR)
147 July 19 18h 13692 0.48 ps.gz 0.53 gif 1, gif 2 99020316B57? Serial number uncertain; logbook inconsistent. (SR)
144 July 17 21h 15007 1.43 ps.gz 1.70 gif 1, gif 2 80012515C54? Minor problem around 8.5 km. Wind speed out around 8.5 km. (BB) Serial number uncertain; logbook inconsistent. (SR)
141 July 15 13h 18783 0.87 ps.gz 1.01 gif 1, gif 2 99020316C63 Wind speed out around 9.8 km. (BB)
140 July 14 14h 17842 0.88 ps.gz 1.04 gif 1, gif 2 99020316C24 Minor problem around 14.5 km. Wind speed out around 9.8 km. (BB)
139 July 13 19h 18256 0.37 ps.gz 0.41 gif 1, gif 2 99020316D16 Minor problem near surface. (BB)
138 July 13 15h 19010 0.35 ps.gz 0.39 gif 1, gif 2 99020316D06
137 July 12 19h 18980 0.67 ps.gz 0.77 gif 1, gif 2 99020316C44 Wind speed out around 14.5 km. (BB)
136 July 12 14h 18346 0.67 ps.gz 0.76 gif 1, gif 2 99020316B48
135 July 3 16h 19441 ps.gz gif 1, gif 2 Humidity sensor broken. (BB)
134 July 1 13h 19297 1.01 ps.gz 1.11 gif 1, gif 2
133 July 1 10h 14358 0.66 ps.gz 0.77 gif 1, gif 2 Minor problems around 6.7 & 12.3 km. (BB)
132 June 30 16h 19332 1.08 ps.gz 1.15 gif 1, gif 2 Minor problem around 16.2 km. (BB)
131 June 30 13h 19236 1.00 ps.gz 1.08 gif 1, gif 2
130 June 30 10h 11974 1.03 ps.gz 1.13 gif 1, gif 2
129 June 28 13h 16820 1.47 ps.gz 1.73 gif 1, gif 2 Problems at 15.4 km. Some 9999's for Az & El. (BB)
128 June 28 11h 13988 1.36 ps.gz 1.61 gif 1, gif 2 Problems at 9.2 km. Some 9999's for Az & El. (BB)
127 June 27 18h 17706 0.51 ps.gz 0.57 gif 1, gif 2 Relatively poor flight. Major problems at 13.5 & 16.6 km. (BB)
126 June 27 15h 17895 0.36 ps.gz 0.40 gif 1, gif 2 Oddities at 8890 and 16500 m. Other minor problems. (BB)
125 June 26 18h 19588 0.47 ps.gz 0.50 gif 1, gif 2 Crazy El values. Minor problems at 19.1 km. (BB)
124 June 26 16h 15722 0.46 ps.gz 0.53 gif 1, gif 2 Minor problems at 12.0 km. Wierdness in the altitudes at the end, probably due to temperature, which got stuck at -72.26. I cut off all values after temperature stopped changing. Note at the same time the temperature stuck at -72.26, the battery voltage went to 99.990. Wind speed also out around 10 km. (BB)
122 June 8 20h 19720 0.64 ps.gz 0.69 gif 1, gif 2
121 June 8 14h 19182 0.26 ps.gz 0.29 gif 1, gif 2
120 June 7 16h 18979 0.62 ps.gz 0.68 gif 1, gif 2 Oddities at 8535 m. (BB)
119 June 5 15h 7235 2.69 ps.gz 2.95 gif 1, gif 2
118 June 1 14h gif 1, gif 2 Az & El readings to to 9999 at 5935 m. Beyond that, ascent rate starts to slowly increase, and altitude readings go to 55000 m! Altitudes not believable - if we want to use this data, we'll likely have to recompute altitude if we can from pressure. It appears what happened was the temperature sensor dropped out. It goes to -11.03 at 6000 m, and stays there all the way up. This is why altitude is messed up, since the geopotential altitude uses the temperature. (BB)
116 April 13 5h 5544 1.30 ps.gz Very short flight??? (BB)

1999

Flight UT Launch Date* & Data Analysis Type 5A Sonde Serial Number Comments
NRAO ESO Cornell
114 November 12 14h ps.gz gif 99020316C30
113 November 11 13h ps.gz gif 1, gif 2 gif 99011916C41
111 November 10 18h ps.gz gif 1, gif 2 gif 99012615B62
110 November 10 12h ps.gz gif 1, gif 2 gif 99012814D55
109 November 10 9h ps.gz gif 1, gif 2 gif 99020316C55
108 November 10 4h ps.gz gif 1, gif 2 gif 99012814C00
107 November 10 0h ps.gz gif 1, gif 2 gif 99012116C34? Serial number uncertain; logbook inconsistent. (SR)
105 November 9 18h ps.gz gif 1, gif 2 gif
104 November 9 15h ps.gz gif 1, gif 2 gif 99111016C04
102 November 9 13h ps.gz gif 1, gif 2 gif 98111016D39? Serial number uncertain; logbook incomplete. (SR)
98 November 8 19h ps.gz gif 1, gif 2 gif 98111016D30
97 November 8 13h ps.gz gif 1, gif 2 gif 98111016D10
96 November 8 9h ps.gz gif 1, gif 2 gif
95 November 8 4h ps.gz gif 1, gif 2 gif 98110712D32
92 November 8 0h ps.gz gif 1, gif 2 gif 9811? Serial number uncertain; logbook incomplete. (SR)
91 November 7 19h ps.gz gif 1, gif 2 gif
88 November 7 18h ps.gz gif
87 November 7 12h ps.gz gif 1, gif 2 gif 98092610C10
86 November 7 10h ps.gz gif 1, gif 2 gif 98092610B32
85 November 7 4h ps.gz gif 1, gif 2 gif 98092610B53
84 November 7 1h ps.gz gif 1, gif 2 gif 98111016D07
82 November 6 18h ps.gz gif 1, gif 2 gif
78 November 6 12h ps.gz gif 98092514B36
77 November 6 9h ps.gz gif 1, gif 2 gif 98092610A60
76 November 6 4h ps.gz gif 1, gif 2 gif 99110604DA7? or 99110604D47? (SR)
75 November 6 1h ps.gz gif 1, gif 2 gif
74 November 5 18h ps.gz gif 1, gif 2 gif 98092610A58 Serial number uncertain; logbook incomplete. (SR)
73 November 5 16h ps.gz gif 1, gif 2 gif
69 November 5 10h ps.gz gif 1, gif 2 gif 98092610A57 San Pedro launch
68 November 5 0h ps.gz gif 1, gif 2 gif San Pedro launch
67 November 4 12h ps.gz gif 98092514A23
64 November 4 10h ps.gz 98092610848? or 98092610B48? (SR) Premature software abort.
60 November 4 9h ps.gz 99020316C02 Premature software abort
56 November 4 2h ps.gz gif 99020316B46
54 November 3 19h ps.gz gif
53 March 14 15h ps.gz gif 1, gif 2 gif
52 March 10 18h ps.gz gif 1, gif 2 gif
51 March  9 15h ps.gz gif 1, gif 2 gif
44 March  6 15h ps.gz gif To 19437 m. (BB)
43 March  4 15h ps.gz gif To 18838 m. (BB)
42 February 17 18h ps.gz gif

1998

Flight UT Launch Date* & Data Analysis Type 5A Sonde Serial Number Comments
NRAO ESO Cornell
41 December 12  5h ps.gz gif
40 December 11 23h ps.gz gif
39 December 11 15h ps.gz gif
37 December 11  5h ps.gz gif
36 December 10 23h ps.gz gif
35 December 10 15h ps.gz gif
34 December 10  5h ps.gz gif
33 December  9 23h ps.gz gif
32 December  9 15h ps.gz gif
31 December  9  5h ps.gz gif
30 December  8 22h ps.gz gif
29 December  8  5h ps.gz gif
28 December  7 23h ps.gz gif
27 December  7 14h ps.gz gif
26 December  7  5h ps.gz gif
25 December  6 23h ps.gz gif
24 December  5 23h ps.gz gif
23 December  5 15h ps.gz gif
22 November 27 20h ps.gz gif 1, gif 2 gif 98073115C50
21 November 27 15h ps.gz gif 1, gif 2 gif 98080109C09
20 November 26 21h ps.gz gif 1, gif 2 gif 98073115A30
19 November 26 15h ps.gz gif 1, gif 2 gif 98080109A35
18 November 25 21h ps.gz gif 1, gif 2 gif 98080109B44
17 November 25 16h ps.gz gif 1, gif 2 gif 98080109A54
15 November 24 23h ps.gz gif 1, gif 2 gif 98080109B33
14 November 24 16h ps.gz gif 1, gif 2 98073115A24
13 November 24 11h ps.gz gif 1, gif 2 gif Tracking problems
12 November 24  5h ps.gz gif 1, gif 2 gif 98080109C10
11 October 25 21h ps.gz gif 1, gif 2 gif
10 October 25 12h ps.gz gif 1, gif 2 gif
8 October 24 14h ps.gz gif 1, gif 2 gif
7 October 12 18h ps.gz gif 1, gif 2 gif
6 October 12  2h ps.gz gif 1, gif 2 gif
5 October 11 16h ps.gz gif 1, gif 2 gif
4 October 11  3h ps.gz gif 1, gif 2 gif
3 October 10  3h ps.gz gif 1, gif 2 gif 98073107B61
2 October  9 17h ps.gz gif 1, gif 2 gif 98073107B32
3 August 31 22h ps.gz Tucson test flight
2 August 21 15h ps.gz Tucson test flight
Duplicate flight numbers.
* Nominal launch times indicate start of flight software. Actual launch times recorded in data files may be later.

The data are in text format, the analysis plots in gif or compressed postscript (ps.gz). Missing flight numbers were ground tests or aborts. Notes by Bryan Butler (BB), Simon Radford (SR) and others.

Sonde serial numbers

Vaisala: The radiosonde serial numbers are assigned when the sensor packs are calibrated. The numbers encode the calibration date and other information. Prior to 1995 October, the RS-80 serial number code was:
DDMMYTTPP, where

  DD = day of the month (1-31)
  MM = month (1-12) + facility identifier (00, 20, 40, or 80)
   Y = last digit of the year     
  TT = calibration tray identifier
  PP = position in calibration tray

More recent RS-80 radiosonde serial numbers are coded:

YWWDTTTNN, where

   Y = last digit of the year
  WW = week number (1-52)
   D = day of the week (1-7) Monday=1
 TTT = calibration tray identifer
  NN = position in calibration tray

RS-90 radiosondes are coded:

YWWDSSSS, where

   Y = alphabetic code for the year (T=1998, U=1999, etc.)
  WW = week number (1-52)
   D = day of the week (1-7) Monday=1
SSSS = sequence number
[Notes from the DOE Atmospheric Radiation Measurment Program, Balloon-Borne Sounding System, radisonde FAQs.]

AIR: Model IS-5A-1680 The radiosonde serial numbers are apparently coded as:

YYMMDDxxaxx, where

   YY = last digits of the year (80 for 2000)     
   MM = month (1-12)
   DD = day of the month (1-31)
xxaxx = sequence number

Last modified 2003 December 30
Simon Radford