Trade-wind clouds and aerosols characterized by airborne horizontal lidar measurements during the EUREC&amp;lt;sup&amp;gt;4&amp;lt;/sup&amp;gt;A field campaign

Chazette, Patrick; Totems, Julien; Baron, Alexandre; Flamant, Cyrille; Bony, Sandrine

doi:10.5194/essd-12-2919-2020

Cited by 20 publications

(44 citation statements)

References 35 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Between the surface of the lake and 2.5 km a.m.s.l., we find δ 18 O values are in the lower range to those recorded by Craig and Gordon (1965) for evaporation over the Mediter-Figure 8. Vertical profiles of the isotope composition δ 2 H from CRDS (ULA-IC), specific humidity (from WALI and meteorological probes aboard ULA), potential temperature (from meteorological probe of ULA-A), wind speed components from the wind lidar, and apparent scattering ratio (ASR) derived from the airborne lidar ALiAS (ULA-A) on (a) 17 June in the morning (∼ 10:30-12:00 LT), (b) 17 June in the afternoon (∼ 16:00-18:30 LT), (c) 18 June in the morning (∼ 11:00-12:30 LT), and 18 June in the afternoon (∼ 16:00-18:00 LT).…”

Section: Statistical Overview Of Isotopic Content From the Lake To The Atmospherecontrasting

confidence: 48%

See 1 more Smart Citation

Experimental investigation of the stable water isotope distribution in an Alpine lake environment (L-WAIVE)

Chazette

Flamant²,

Sodemann

et al. 2021

Atmos. Chem. Phys.

Self Cite

View full text Add to dashboard Cite

Abstract. In order to gain understanding on the vertical structure of atmospheric water vapour above mountain lakes and to assess its link with the isotopic composition of the lake water and with small-scale dynamics (i.e. valley winds, thermal convection above complex terrain), the L-WAIVE (Lacustrine-Water vApor Isotope inVentory Experiment) field campaign was conducted in the Annecy valley in the French Alps during 10 d in June 2019. This field campaign was based on an original experimental synergy between a suite of ground-based, boat-borne, and two ultra-light aircraft (ULA) measuring platforms implemented to characterize the thermodynamic and isotopic composition above and in the lake. A cavity ring-down spectrometer and an in-cloud liquid water collector were deployed aboard one of the ULA to characterize the vertical distribution of the main stable water isotopes (H216O, H218O and H2H16O) both in the air and in shallow cumulus clouds. The temporal evolution of the meteorological structures of the low troposphere was derived from an airborne Rayleigh–Mie lidar (embarked on a second ULA), a ground-based Raman lidar, and a wind lidar. ULA flight patterns were repeated several times per day to capture the diurnal evolution as well as the variability associated with the different weather events encountered during the field campaign, which influenced the humidity field, cloud conditions, and slope wind regimes in the valley. In parallel, throughout the campaign, liquid water samples of rain, at the air–lake water interface, and at 2 m depth in the lake were taken. A significant variability of the isotopic composition was observed along time, depending on weather conditions, linked to the transition from the valley boundary layer towards the free troposphere, the valley wind intensity, and the vertical thermal stability. Thus, significant gradients of isotopic content have been revealed at the transition to the free troposphere, at altitudes between 2.5 and 3.5 km. The influence of the lake on the atmosphere isotopic composition is difficult to isolate from other contributions, especially in the presence of thermal instabilities and valley winds. Nevertheless, such an effect appears to be detectable in a layer of about 300 m thickness above the lake in light wind conditions. We also noted similar isotopic compositions in cloud drops and rainwater.

show abstract

Section: Statistical Overview Of Isotopic Content From the Lake To The Atmospherecontrasting

confidence: 48%

“…The link between hydrology and evaporation has mainly been investigated using vapour and liquid water isotopes measurements gathered just above the Earth's surface and samples from lake water and precipitation (e.g. Cui et al, 2016).…”

mentioning

confidence: 99%

Experimental investigation of the stable water isotope distribution in an Alpine lake environment (L-WAIVE)

Chazette

Flamant²,

Sodemann

et al. 2021

Atmos. Chem. Phys.

Self Cite

View full text Add to dashboard Cite

show abstract

“…During EUREC 4 A, multiple days with Saharan dust arriving above Barbados have been observed. Aircraft-based lidar (Chazette et al, 2020; and stable water isotope measurements have been performed in this period, which provides the data basis to investigate this aspect in more detail.…”

Section: Discussionmentioning

confidence: 99%

“…The water vapour isotope measurements and event-based precipitation samples from isoTrades served as a basis for the planning of the multi-platform isotope measurements on four ships, two aircraft and at the BCO performed during EUREC 4 A-iso by several European and US American teams. The stable water isotope composition of a water sample is usually quantified by the δ notation (Craig, 1961a):…”

Section: Stable Water Isotope Measurements At the Barbados Cloud Obsementioning

confidence: 99%

How Rossby wave breaking modulates the water cycle in the North Atlantic trade wind region

Aemisegger

Vogel²,

Graf

et al. 2021

Weather Clim. Dynam.

Self Cite

View full text Add to dashboard Cite

Abstract. The interaction between low-level tropical clouds and the large-scale circulation is a key feedback element in our climate system, but our understanding of it is still fragmentary. In this paper, the role of upper-level extratropical dynamics for the development of contrasting shallow cumulus cloud patterns in the western North Atlantic trade wind region is investigated. Stable water isotopes are used as tracers for the origin of air parcels arriving in the sub-cloud layer above Barbados, measured continuously in water vapour at the Barbados Cloud Observatory during a 24 d measurement campaign (isoTrades, 25 January to 17 February 2018). These data are combined with a detailed air parcel back-trajectory analysis using hourly ERA5 reanalyses of the European Centre for Medium-Range Weather Forecasts. A climatological investigation of the 10 d air parcel history for January and February in the recent decade shows that 55 % of the air parcels arriving in the sub-cloud layer have spent at least 1 d in the extratropics (north of 35∘ N) before arriving in the eastern Caribbean at about 13∘ N. In 2018, this share of air parcels with extratropical origin was anomalously large, with 88 %. In two detailed case studies during the campaign, two flow regimes with distinct isotope signatures transporting extratropical air into the Caribbean are investigated. In both regimes, the air parcels descend from the lower part of the midlatitude jet stream towards the Equator, at the eastern edge of subtropical anticyclones, in the context of Rossby wave breaking events. The zonal location of the wave breaking and the surface anticyclone determine the dominant transport regime. The first regime represents the “typical” trade wind situation, with easterly winds bringing moist air from the eastern North Atlantic into the Caribbean, in a deep layer from the surface up to ∼600 hPa. The moisture source of the sub-cloud layer water vapour is located on average 2000 km upstream of Barbados. In this regime, Rossby wave breaking and the descent of air from the extratropics occur in the eastern North Atlantic, at about 33∘ W. The second regime is associated with air parcels descending slantwise by on average 300 hPa (6 d)−1 directly from the north-east, i.e. at about 50∘ W. These originally dry airstreams experience a more rapid moistening than typical trade wind air parcels when interacting with the subtropical oceanic boundary layer, with moisture sources being located on average 1350 km upstream to the north-east of Barbados. The descent of dry air in the second regime can be steered towards the Caribbean by the interplay of a persistent upper-level cut-off low over the central North Atlantic (about 45∘ W) and the associated surface cyclone underneath. The zonal location of Rossby wave breaking and, consequently, the pathway of extratropical air towards the Caribbean are shown to be relevant for the sub-cloud layer humidity and shallow-cumulus-cloud-cover properties of the North Atlantic winter trades. Overall, this study highlights the importance of extratropical dynamical processes for the tropical water cycle and reveals that these processes lead to a substantial modulation of stable water isotope signals in the near-surface humidity.

show abstract

“…The study presented in this article is a follow-up to the EUREC 4 A (Elucidating the role of clouds-circulation coupling in climate) field campaign (Bony et al, 2017) which took place in 5 January-February 2020 over the western tropical Atlantic, West of Barbados (Stevens et al, 2021). During the airborne measurements performed from the French research aircraft ATR-42 operated by the Service des Avions Français Instrumentés pour la Recherche en Environnement (SAFIRE), a variety of aerosol optical property signatures were observed (Chazette et al, 2020) and the objective of this paper is to describe their origin and the meteorological conditions that 10 led to their observation over the Barbados region. Airborne observations of atmospheric aerosols off the coast of Barbados are scarce, especially in winter.…”

mentioning

confidence: 99%

Mesoscale spatio-temporal variability of airborne lidar-derived aerosol properties in the Barbados region during EUREC⁴A

Chazette

Baron

Flamant

2021

Preprint

Self Cite

View full text Add to dashboard Cite

Abstract. From 23 January to 13 February 2020, twenty ATR-42 scientific flights were conducted in the framework of the EUREC4A field campaign over the tropical Atlantic, off the coast of Barbados (−58°30' W 13°30' N). By means of a side-pointing lidar, these flights allowed to retrieve the optical properties of the aerosols found in the sub-cloud layer and below the trade winds inversion. Two distinct periods with significant aerosol contents were identified in relationship with the so-called trade wind and tropical regimes, respectively. A very strong spatial heterogeneity of the aerosol field has been highlighted at the airborne measurements scale of a few tens of kilometres. This heterogeneity, difficult to capture using spaceborne instruments, can be related to the highly variable relative humidity field and the fractional cloud cover encountered during all the flights.

show abstract

Trade-wind clouds and aerosols characterized by airborne horizontal lidar measurements during the EUREC<sup>4</sup>A field campaign

Cited by 20 publications

References 35 publications

Experimental investigation of the stable water isotope distribution in an Alpine lake environment (L-WAIVE)

Experimental investigation of the stable water isotope distribution in an Alpine lake environment (L-WAIVE)

How Rossby wave breaking modulates the water cycle in the North Atlantic trade wind region

Mesoscale spatio-temporal variability of airborne lidar-derived aerosol properties in the Barbados region during EUREC⁴A

Contact Info

Product

Resources

About

Trade-wind clouds and aerosols characterized by airborne horizontal lidar measurements during the EUREC&lt;sup&gt;4&lt;/sup&gt;A field campaign

Cited by 20 publications

References 35 publications

Experimental investigation of the stable water isotope distribution in an Alpine lake environment (L-WAIVE)

Experimental investigation of the stable water isotope distribution in an Alpine lake environment (L-WAIVE)

How Rossby wave breaking modulates the water cycle in the North Atlantic trade wind region

Mesoscale spatio-temporal variability of airborne lidar-derived aerosol properties in the Barbados region during EUREC4A

Contact Info

Product

Resources

About

Trade-wind clouds and aerosols characterized by airborne horizontal lidar measurements during the EUREC<sup>4</sup>A field campaign

Mesoscale spatio-temporal variability of airborne lidar-derived aerosol properties in the Barbados region during EUREC⁴A