1 INTRODUCTION

1.1 This AIP Supplement is to inform airline operators and pilots of a weather balloon launch with dual radiosondes with effect from 22 September 2022, 0100UTC to 21 June 2023, 0100UTC.

2 CURRENT DAILY WEATHER BALLOON RELEASE

2.1 Balloons are routinely released for MET observations at the Centre for Climate Research Operations, Upper Air Observatory (012025N 1035317E) twice daily at 2330UTC and 1040UTC. Each of this balloon has only a single radiosonde attached. Please see the following Singapore AIP section and charts for details of the current operations:

1. ENR 5.3 Sub-section 5.3.1 - OTHER ACTIVITIES OF DANGEROUS NATURE;
   

2. ENR 3.6-7/Area Chart - LOW LEVEL HOLDING AREAS, Flip-side, Special Note 1 (I) and (II); and
   

3. ENR 3.6-9/Area Chart - HIGH LEVEL HOLDING AREAS, Flip-side, Special Note 1 (I) and (II).

3 TWICE-MONTHLY DUAL RADIOSONDE OPERATION

3.1 With effect from 22 September 2022, 0100UTC, there will be a launch with dual radiosondes two times per month for a period of nine months to meet WMO requirement for radiosonde calibration.

3.2 Details of the balloon launch with dual-sonde are listed below and a graphic of dual-sonde setup is shown in Annex A.

Frequency of the release: two times per month
Week of the release: on the 2nd and 4th week
Timing of the release: at 2330UTC (with cut-off timings at 0030UTC).

Note: This launch replaces the normal single-sonde launch on the same day/time.

Rate of ascent of balloon: 320m per minute.
Maximum height of balloon: 115 000ft (35 000m).
Colour of balloon: uncoloured.
Diameter of balloon: 162m.

The balloon is attached with 2 radiosondes (connected with a rod)
Weight of radiosonde-1: 80g.
Size of radiosonde-1: 155 x 63 x 46 mm.
Weight of radiosonde-2: 40g.
Size of radiosonde-2: 131 x 55 x 53 mm.

Payload (radiosondes and connecting rod): 150g.

4 CONCLUSION

4.1 Any change to the contents of this AIP Supplement will be notified through NOTAM.

Dual-sonde Setup