scholarly journals Aerosol characterization in an oceanic context around Reunion Island (AEROMARINE field campaign)

2022 ◽  
Vol 268 ◽  
pp. 118770
Author(s):  
Faustine Mascaut ◽  
Olivier Pujol ◽  
Bert Verreyken ◽  
Raphaël Peroni ◽  
Jean Marc Metzger ◽  
...  
Keyword(s):  
Reunion Island ◽  
Field Campaign ◽  
Réunion Island ◽  
Aerosol Characterization

Aerosol characterization in an oceanic context around Reunion island (AEROMARINE field campaign)

2021 ◽  
Author(s):  
Faustine Mascaut ◽  
Olivier Pujol ◽  
Jérôme Brioude ◽  
Bert Verreyken ◽  
Raphaël Peroni ◽  
...  
Keyword(s):  
Indian Ocean ◽  
High Altitude ◽  
Atmospheric Environment ◽  
Reunion Island ◽  
Free Troposphere ◽  
Marine Aerosols ◽  
Field Campaign ◽  
Air Masses ◽  
Major Interest ◽  
Réunion Island

<p>We present the results of the AEROMARINE field campaign which took place in the boreal spring 2019 off the coast of Reunion island in the South West Indian Ocean basin. The southern Indian Ocean is of major interest for the study of marine aerosols, their distribution and variability <em>[1]</em>. Nine instrumented light plane flights and a ground-based microwave radiometer were used during the AEROMARINE field campaign. These measurements were compared with the long-term measurements of the AERONET sun-photometer (based in Saint Denis, Reunion Island) and various instruments of the high altitude Maido Observatory (2200m above sea level, Reunion island). These results were analyzed using different model outputs: (i) the AROME mesoscale weather forecast model to work on the thermodynamics of the boundary layer, (ii) the FLEXPART-AROME Lagrangian particle dispersion model to assess the geographical and vertical origin of air masses, and (iii) the chemical transport model CAMS (Copernicus Atmosphere Monitoring Service) to work on the aerosol chemical composition of air masses. These measurements allowed us to determine the background concentration of natural marine aerosols and to highlight that (1) the atmospheric layers above 1500m are in the free troposphere and are mainly composed of aerosols from the regional background and (2) that the local environment (ocean or island) has little impact on the measured concentrations. Marine aerosols emitted locally are mostly measured in the lower atmospheric layers (below 500m). The daytime marine aerosol distributions in the free troposphere measured by the aircraft were compared to the aerosol distribution measured at the high altitude Maido observatory at night when the observatory is located in the free troposphere.  We also found that the CAMS reanalyses overestimated the aerosol optical depth in this region. Finally, our study confirms, with no ambiguity, that the AERONET station in Saint Denis (Reunion island) can be considered as a representative marine station in the tropics <em>[2]</em>. </p><p><br><br>References<br><em>[1]</em>  I.  Koren,  G.  Dagan,  and  O.  Altaratz.   From  aerosol-limited  to  invigoration  of  warm  convective clouds. Science, 344 (6188) : 1143–1146, 2014.<br><em>[2] </em> P. Hamill, M. Giordano, C. Ward, D. Giles, and B. Holben.  An aeronet-based aerosol classification using the mahalanobis distance. Atmospheric Environment, 140 : 213–233,2016.</p>

scholarly journals Cloud Radar Observations of Diurnal and Seasonal Cloudiness over Reunion Island

Atmosphere ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 868
Author(s):  
Jonathan Durand ◽  
Edouard Lees ◽  
Olivier Bousquet ◽  
Julien Delanoë ◽  
François Bonnardot
Keyword(s):  
Sea Breeze ◽  
Satellite System ◽  
Research Infrastructure ◽  
Weather Data ◽  
Reunion Island ◽  
Wet Season ◽  
Trade Winds ◽  
Cloud Radar ◽  
Réunion Island ◽  
Global Navigation Satellite

In November 2016, a 95 GHz cloud radar was permanently deployed in Reunion Island to investigate the vertical distribution of tropical clouds and monitor the temporal variability of cloudiness in the frame of the pan-European research infrastructure Aerosol, Clouds and Trace gases Research InfraStructure (ACTRIS). In the present study, reflectivity observations collected during the two first years of operation (2016–2018) of this vertically pointing cloud radar are relied upon to investigate the diurnal and seasonal cycle of cloudiness in the northern part of this island. During the wet season (December–March), cloudiness is particularly pronounced between 1–3 km above sea level (with a frequency of cloud occurrence of 45% between 12:00–19:00 LST) and 8–12 km (with a frequency of cloud occurrence of 15% between 14:00–19:00 LST). During the dry season (June–September), this bimodal vertical mode is no longer observed and the vertical cloud extension is essentially limited to a height of 3 km due to both the drop-in humidity resulting from the northward migration of the ITCZ and the capping effect of the trade winds inversion. The frequency of cloud occurrence is at its maximum between 13:00–18:00 LST, with a probability of 35% at 15 LST near an altitude of 2 km. The analysis of global navigation satellite system (GNSS)-derived weather data also shows that the diurnal cycle of low- (1–3 km) and mid-to-high level (5–10 km) clouds is strongly correlated with the diurnal evolution of tropospheric humidity, suggesting that additional moisture is advected towards the island by the sea breeze regime. The detailed analysis of cloudiness observations collected during the four seasons sampled in 2017 and 2018 also shows substantial differences between the two years, possibly associated with a strong positive Indian Ocean Southern Dipole (IOSD) event extending throughout the year 2017.

Differential diagnoses of severe COVID‐19 in tropical areas: The experience of Reunion Island

2020 ◽  
Author(s):  
Pauline Krol ◽  
Nathalie Coolen‐Allou ◽  
Laura Teysseyre ◽  
Nicolas Traversier ◽  
Floryan Beasley ◽  
...  
Keyword(s):  
Differential Diagnoses ◽  
Reunion Island ◽  
Réunion Island ◽  
Tropical Areas

scholarly journals Evaluation of WRF-DART (ARW v3.9.1.1 and DART Manhattan release) multiphase cloud water path assimilation for short-term solar irradiance forecasting in a tropical environment

2019 ◽  
Vol 12 (9) ◽  
pp. 3939-3954
Author(s):  
Frederik Kurzrock ◽  
Hannah Nguyen ◽  
Jerome Sauer ◽  
Fabrice Chane Ming ◽  
Sylvain Cros ◽  
...  
Keyword(s):  
Data Assimilation ◽  
Weather Prediction ◽  
Cloud Water ◽  
Specific Humidity ◽  
Reunion Island ◽  
Short Term ◽  
Water Path ◽  
Réunion Island ◽  
Cloud Water Path ◽  
The Impact

Abstract. Numerical weather prediction models tend to underestimate cloud presence and therefore often overestimate global horizontal irradiance (GHI). The assimilation of cloud water path (CWP) retrievals from geostationary satellites using an ensemble Kalman filter (EnKF) led to improved short-term GHI forecasts of the Weather Research and Forecasting (WRF) model in midlatitudes in case studies. An evaluation of the method under tropical conditions and a quantification of this improvement for study periods of more than a few days are still missing. This paper focuses on the assimilation of CWP retrievals in three phases (ice, supercooled, and liquid) in a 6-hourly cycling procedure and on the impact of this method on short-term forecasts of GHI for Réunion Island, a tropical island in the southwest Indian Ocean. The multilayer gridded cloud properties of NASA Langley's Satellite ClOud and Radiation Property retrieval System (SatCORPS) are assimilated using the EnKF of the Data Assimilation Research Testbed (DART) Manhattan release (revision 12002) and the advanced research WRF (ARW) v3.9.1.1. The ability of the method to improve cloud analyses and GHI forecasts is demonstrated, and a comparison using independent radiosoundings shows a reduction of specific humidity bias in the WRF analyses, especially in the low and middle troposphere. Ground-based GHI observations at 12 sites on Réunion Island are used to quantify the impact of CWP DA. Over a total of 44 d during austral summertime, when averaged over all sites, CWP data assimilation has a positive impact on GHI forecasts for all lead times between 5 and 14 h. Root mean square error and mean absolute error are reduced by 4 % and 3 %, respectively.

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