Preprints
https://doi.org/10.5194/amt-2021-206
https://doi.org/10.5194/amt-2021-206

  18 Aug 2021

18 Aug 2021

Review status: this preprint is currently under review for the journal AMT.

Thermodynamic model for a pilot balloon

Vicent Favà1, Juan José Curto1, and Alba Gilabert2 Vicent Favà et al.
  • 1Observatori de l’Ebre, (OE) CSIC – Universitat Ramon Llull, Roquetes, Spain
  • 2Centre for Climate Change, Department of Geography, Universitat Rovira i Virgili, Tarragona, Spain

Abstract. In the early part of the 20th century, tracking a pilot balloon from the ground with an optical theodolite was one of the few methods that was able to provide information from the upper air. One of the most significant sources of error with this method, however, was involved in calculating the balloon height as a function of time, a calculation dependent on the ascent rate which was traditionally taken to be constant. This study presents a new thermodynamic model which allows us to compute the thermal jump between the surrounding environment and the lifting gas as a function of different parameters such as the atmospheric temperature lapse rate or the physical characteristics of the balloon. The size of the thermal jump and its effect on the ascent rate is discussed for a 30 g pilot balloon, which was the type used at the Ebro Observatory (EO) between 1952 and 1963. The meridional and zonal components of the wind profile from ground level up to 10 km altitude were computed by applying the model using EO digitized data for a sample of this period. The obtained results correlate very well with those obtained from the ERA5 reanalysis. A very small thermal jump with a weak effect on the computed ascent rate was found. This ascent rate is consistent with the values assigned in that period to the balloons filled with hydrogen used at the Ebro Observatory and to the 30 g balloons filled with helium used by the US National Weather Service.

Vicent Favà et al.

Status: open (until 01 Dec 2021)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on amt-2021-206', Anonymous Referee #1, 12 Nov 2021 reply
  • RC2: 'Referee comment on amt-2021-206', Anonymous Referee #2, 25 Nov 2021 reply

Vicent Favà et al.

Vicent Favà et al.

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Short summary
In the early part of the 20th century, tracking a pilot balloon from the ground was one of the few methods that was able to provide information from the upper air. 30 g pilot balloon were used at many meteorological observatories as at Ebro Observatory (Spain) for this purpose. This study presents a new thermodynamic model which allows us to compute the different parameters affecting the ascent rate of these balloons, essential to obtain the meridional and zonal components of the wind profile.