ILRC29 – International Laser Radar Conference (Hefei – China)

ILRC29 – International Laser Radar Conference (Hefei – China)

June, 24-28 2019

After 50 years, for the first time, the 29th ILRC came to China! ILRC is held biennially under the oversight of the ICLAS, of the International Radiation Commission (IRC). The 29th ILRC was co-hosted by six institutes/universities in China and supported by the Chinese Academy of Sciences and Hefei municipal government. It is also persistently supported by the National Aeronautics and Space Administration (NASA), the European Space Agency (ESA), and many international/national partners and enterprises.

During the 29th ILRC, the new lidar technologies and techniques for profiling the aerosol and clouds, trace gases, water vapor, temperature, turbulence and 3D-wind were explored. The application of lidar networking and space-borne lidars were  investigated. Emphasis was given to weather forecasting, environmental and climate change investigations combined with multiple instruments and platforms. The lidar technologies extended to ocean, land surface and biological applications were also present.

The 29th ILRC was an excellent opportunity to share and exchange ideas. We would like to thank everyone who came at Cimel’s booth and poster presentation during ILRC29. We were pleased to welcome you all!

Paris declares itself in a “state of climatic emergency”

Paris declares itself in a “state of climatic emergency”

July 9, 2019

The City of Paris has adopted the creation of an “IPCC” (Intergovernmental Panel on Climate Change), which will bring together experts (climatologists, urban designers, sociologists, etc.). They will be able to be consulted and play a “constant role in the implementation of climate policies”.

Like many world cities or more recently the Parliaments of the United Kingdom and Ireland, the City of Paris has declared itself in a “state of climatic emergency“. This decision was taken during a vote in the Paris Council on Tuesday, July 9. We must “meet the objectives of the Paris Agreement” adopted in December 2015, argued the assistant in charge of the Environment to the mayor of Paris, Célia Blauel.

Creation of an “IPCC Paris”

During the session, the City of Paris adopted the creation of an “IPCC Paris” which will bring together experts (climatologists, urban designers, sociologists…). They will be able to be consulted and play a “constant role in the implementation of climate policies”, added Célia Blauel.

A few months before the municipal elections, the mayor of Paris Anne Hidalgo and her entourage have not ceased to multiply ecological projects: after the pedestrianisation of the roads on the banks, the Paris City Hall has, among other things, multiplied projects in favour of a complete greening of the streets and squares of the capital or announced the creation of “urban forests” in the middle of the city to fight against global warming and the effects of pollution.

A 10-year characterization of the Saharan Air Layer lidar ratio in the subtropical North Atlantic

A 10-year characterization of the Saharan Air Layer lidar ratio in the subtropical North Atlantic

May 10, 2019

Particle extinction-to-backscatter ratio (lidar ratio) is a key parameter for a correct interpretation of elastic lidar measurements. Of particular importance is the determination of the lidar ratio of the Saharan Air Layer mineral dust transported into the free troposphere over the North Atlantic region. The location of the two sun photometer stations managed by the Izaña Atmospheric Research Centre (IARC) on the island of Tenerife and a decade of available micropulse lidar (MPL) data allow us to determine the lidar ratio under almost pure-dust conditions. This result can be considered representative of the Saharan dust transported westward over the North Atlantic in the subtropical belt.

Three different methods have been used to calculate the lidar ratio in this work: (1) using the inversion of sky radiance measurements from a sun–sky photometer installed at the Izaña Observatory (2373 m a.s.l.) under free-troposphere conditions; (2) the one-layer method, a joint determination using a micropulse lidar sited at the Santa Cruz de Tenerife sea-level station and photometric information considering one layer of aerosol characterized by a single lidar ratio; and (3) the two-layer method, a joint determination using the micropulse lidar and photometric information considering two layers of aerosol with two different lidar ratios. The one-layer method only uses data from a co-located photometer at Santa Cruz de Tenerife, while the two-layer conceptual approach incorporates photometric information at two heights from the observatories of Izaña and Santa Cruz de Tenerife. The almost pure-dust lidar ratio retrieval from the sun–sky photometer and from the two-layer method give similar results, with lidar ratios at 523 nm of 49 ± 6 and 50 ± 11 sr. These values obtained from a decade of data records are coincident with other studies in the literature reporting campaigns in the subtropical North Atlantic region. This result shows that the two-layer method is an improved conceptual approach compared to the single-layer approach, which matches the real lower-troposphere structure well. The two-layer method is able to retrieve reliable lidar ratios and therefore aerosol extinction profiles despite the inherent limitations of the elastic lidar technique.

We found a lack of correlation between lidar ratio and Ångström exponent (α), which indicates that the dust lidar ratio can be considered independent of dust size distribution in this region. This finding suggests that dust is, under most atmospheric conditions, the predominant aerosol in the North Atlantic free troposphere, which is in agreement with previous studies conducted at the Izaña Observatory.

Citation: Berjón, A., Barreto, A., Hernández, Y., Yela, M., Toledano, C., and Cuevas, E.: A 10-year characterization of the Saharan Air Layer lidar ratio in the subtropical North Atlantic, Atmos. Chem. Phys., 19, 6331-6349, https://doi.org/10.5194/acp-19-6331-2019, 2019.

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