Preprints
https://doi.org/10.5194/amt-2024-8
https://doi.org/10.5194/amt-2024-8
18 Mar 2024
 | 18 Mar 2024
Status: this preprint is currently under review for the journal AMT.

In situ observations of supercooled liquid water clouds over Dome C, Antarctica by balloon-borne sondes

Philippe Ricaud, Pierre Durand, Paolo Grigioni, Massimo Del Guasta, Giuseppe Camporeale, Axel Roy, Jean-Luc Attié, and John Bognar

Abstract. Clouds in Antarctica are key elements that affect radiative forcing and thus Antarctic climate evolution. Although the vast majority of clouds are composed of ice crystals, a non-negligible fraction is constituted of supercooled liquid water (SLW, water held in liquid form below 0 °C). Numerical weather prediction models have a great difficulty to forecast SLW clouds over Antarctica favouring ice at the expense of liquid water, and therefore incorrectly estimating the cloud radiative forcing. Remote sensing observations of SLW clouds have been carried out for several years at Concordia station (75° S, 123° E, 3233 m above mean sea level), combining active LIDAR measurements (SLW cloud detection) and passive HAMSTRAD microwave measurements (liquid water path, LWP). The present project aimed at in situ observations of SLW clouds using sondes developed by the company Anasphere, specifically designed for SLW content (SLWC) measurements. These SLWC sondes were coupled to standard meteorological pressure-temperature-humidity sondes from the Vaisala Company and released under meteorological balloons. During the 2021–2022 summer campaign, 15 launches were made, of which 7 were scientifically exploitable. Above a height of 400 m above ground level, we found that the SLWC sondes detected SLW clouds in a vertical range consistent with LIDAR observations. In nominal operation, the LWP values obtained either by HAMSTRAD or vertically-integrated from the SLWC sonde profiles were consistent in spite of their low values (< 10 g m-2). On some occasions far from nominal operation (surface fog, low vertical ascent of the balloon), the LWPs from the SLWC sonde were overestimated by a factor of 5–10 compared to the HAMSTRAD values. In general, the SLW clouds were observed in a layer close to saturation (U > 80 %) or saturated (U ~100–105 %) just below or at the lowermost part of the entrainment zone or capping inversion zone which exists at the top of the Planetary Boundary Layer and is characterized by an inflection point in the potential temperature vertical profiles. Our results are consistent with the theoretical view that SLW clouds form and pertain at the top of the Planetary Boundary Layer.

Philippe Ricaud, Pierre Durand, Paolo Grigioni, Massimo Del Guasta, Giuseppe Camporeale, Axel Roy, Jean-Luc Attié, and John Bognar

Status: open (until 22 Apr 2024)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on amt-2024-8', Anonymous Referee #2, 03 Apr 2024 reply
  • RC2: 'Comment on amt-2024-8', Anonymous Referee #1, 07 Apr 2024 reply
Philippe Ricaud, Pierre Durand, Paolo Grigioni, Massimo Del Guasta, Giuseppe Camporeale, Axel Roy, Jean-Luc Attié, and John Bognar
Philippe Ricaud, Pierre Durand, Paolo Grigioni, Massimo Del Guasta, Giuseppe Camporeale, Axel Roy, Jean-Luc Attié, and John Bognar

Viewed

Total article views: 227 (including HTML, PDF, and XML)
HTML PDF XML Total Supplement BibTeX EndNote
181 34 12 227 22 8 8
  • HTML: 181
  • PDF: 34
  • XML: 12
  • Total: 227
  • Supplement: 22
  • BibTeX: 8
  • EndNote: 8
Views and downloads (calculated since 18 Mar 2024)
Cumulative views and downloads (calculated since 18 Mar 2024)

Viewed (geographical distribution)

Total article views: 219 (including HTML, PDF, and XML) Thereof 219 with geography defined and 0 with unknown origin.
Country # Views %
  • 1
1
 
 
 
 
Latest update: 15 Apr 2024
Download
Short summary
Clouds in Antarctica are key elements affecting climate evolution. Some clouds are constituted of supercooled liquid water (SLW, water held in liquid form below 0 °C) and are difficult to forecast by models. We performed in-situ observations of SLW clouds at Concordia station using SLW sondes attached to meteorological balloons in summer 2021–2022. The SLW clouds were observed in a saturated layer at the top of the Planetary Boundary Layer in agreement with ground-based LIDAR observations.