Research Thesis book cover – Julien Chimot – July 2018
Almost 3 months ago, on 2018.10.10, I had the privilege to defend my research thesis at Delft University Of Technology. A big moment after 4 years of intensive collaboration with my colleagues of Geoscience & Remote Sensing Department and KNMI and in the presence of several friends and relatives. An very strict protocol to follow according to the Dutch rules and tradition.
My thesis book is now available online as an Ebook here! Feel free to have a look if you are interested by aerosol layer height retrieval, UV-Vis satellite measurements such as OMI, troposphericNO2, air quality and climate observations. My main papers are concatenated there.
While the last Intergovernmental Panel on Climate Change (IPPC) report just got released, and stresses the urgency to act extremely quickly for limiting the global warming close to 1.5 deg, one should keep in mind that the worldwide electricity sector is one of the highest source of CO2 – Carbon dioxide released in the atmosphere. Do we want to keep our lights on? Let’s ban then coal gas & use electricity sources with low CO2 – Carbon dioxide emissions (including nuclear!).
Analyses of the trends is possible but overall a challenging and sensitive task. Over 20 years, very different sensor techniques, instrument specificities & degradations, variable pixel sizes, cloud detection possibilities etc… A lot of works to harmonise these data!
Atmosphericaerosol are particles suspended in the air. Their sources are very mixed. Aerosol can be man-made or natural: e.g. smoke, desert dust, sea spray, nitrates and sulfates. The aerosol effects on the sunlight modify the shortwave radiation field in the atmosphere. This directly impacts the climate and the satellite observations devoted to ocean surface, land surface, vegetation, and atmospheric gases. Furthermore, heavy load of aerosols affects our air quality.
In spite of many progresses during the last 10-20 years, aerosol observations from space-borne instruments remain incredibly complex. One of the main reasons is their heterogeneity: aerosols are everywhere, but with very variable quantities spatially (horizontally and vertically!), and temporally. And, as highlighted by this NASA picture, aerosol types are also very heterogeneous! Retrieving all these parameters from single satellite measurements, without ambiguity with respect to surface characteristics and clouds, is the difficult task of the scientists working with atmospheric satellite measurements. Many works to continue to do…
More information
NASA WebPage “Just another Day on Aerosol Earth” here
This paper is based on the last developments we published during 2016, 2017, and 2018. During these years, not only the OMI cloud algorithm was improved (Veefkind et al., 2016), but also an OMIaerosol layer height (and optical thickness) neural network algorithm was developed (Chimot et al., 2017, 2018). This time, we directly evaluate the impacts of these developments to correct of aerosol absorption and scattering effects in the visible spectral range in view of retrieving troposphericNO2, an important trace gas affecting air quality in urban and industrialised areas.
Statistics of relative troposphericNO2 VCD changes in (%) in 2006-2007, due to differences between the different explicit aerosol corrections and the implicit aerosol correction based on OMCLDO2-New: (a), and (b): China summertime (June-July-August), (c), and (d): China wintertime (December-January-February), (e), and (f): South America biomass burning season (August-September).
As part of the Copernicus programme, Sentinel-3 is a very important mission for ocean colour, sea and land surface, fire, atmosphere and climate purposes. With the two platforms, Sentinel-3 A and B, an optimal global coverage will be now obtained. The next observations and related products are promising!
More information?
Check the diverse pictures of this fantastic launch via the Twitter accounts of EUMETSAT and ESA
The current Sentinel-3 services provided by EUMETSAT here
And watch below the movie from EUMETSAT in live in the Sentinel-3 control centre “Sentinel-3: Operating satellites” with Hillary Wilson, EUMETSAT’s Sentinel-3 manager, and Kevin Marston, EUMETSAT’s System operation manager.
This paper is based on the work of 2017, in which a neural network algorithm was developed for retrieving aerosol layer height (ALH) from the OMI O2-O2 visible measurements. This time, we directly compare our retrievals with CALIOPaerosol observations and evaluate the spatial patterns on several remarkable case studies including urban pollution, biomass burning events and a Saharan dust outbreak!
