16 research outputs found
Ground-based MAX-DOAS observation of NO2 and H2CO over Kinshasa and comparisons with GEOS-Chem model data and TROPOMI observation
No full textAfrica experiences an explosive human population growth, leading to different environmental issues. In particular, many African cities are heavily affected by air pollution. It is therefore essential to monitor the concentrations of various polluting species such as NO2, HCHO, O3 and aerosols, which have a direct impact on human health. The sources of pollutants in Africa are different from those found in many industrial areas. For example, forest fires and household cooking largely contribute to the NO2 and HCHO concentrations in Central Africa. However, many large African cities do not have atmospheric measurement instruments that perform continuous measurements.
From May 2017 to early November 2019, a single axis DOAS instrument was installed and performed measurements at the University of Kinshasa (UniKin: -4.42° S, 15.31° E). This installation is the result of a close collaboration between the Belgian Institute for Space Aeronomy (IASB) and the UniKin Faculty of Sciences. Studies based on measurements made with this instrument have demonstrated the presence of a clear yearly cycle of the NO2 concentration with higher values in the dry season (Yombo et al., 2021). With such a low-cost instrument, the information content of the measurements is very limited and the uncertainties of the measurements rather high. . In November 2019, the single axis instrument was replaced by a new MAX-DOAS (multi-axis differential optical absorption spectroscopy) system built at the IASB, increasing substantially the information content of the measurements.
These first Max-DOAS measurements are used to retrieve NO2 and HCHO contents over the city of Kinshasa, utilizing the harmonized FRM4DOAS analysis facility. The two years of MAXDOAS vertical column results of these two molecules are compared to OMI and TROPOMI data. They constitute important validation points in central Africa which currently lacks validation data and hence, these measurements will contribute to improvements of the a priori shape in the lower troposphere. Further, we compare this data set to specific GEOS-Chem chemistry transport model simulations allowing some specific investigations of source attribution. To our knowledge, these DOAS measurements yielded the first multiyear dataset of air quality measurements performed in Kinshasa
ATMOSPHERIC RESEARCH PROGRAM IN KINSHASA(2016-2022)
No full textNous présentons dans ce séminaire, l’importance d’avoir un programme d’observation atmosphérique à Kinshasa, capitale de la République Démocratique du Congo. La ville de Kinshasa regorge plus de 10 millions d’habitants et est située au voisinage de sources de VOC (Composés Organiques Volatils). Les VOC et les autres espèces en trace comme le NO2, SO2,..influencent beaucoup la qualité de l’air. Les recherches actuelles montrent aussi qu’on s’attend à ce que la qualité de l’air dans les zones urbaines, définie en particulier par les concentrations de dioxyde d’azote (NO2) et d’aérosols, puisse se détériorer rapidement au cours des 15 prochaines années (Liousse et al., 2014).
Dans le bassin du Congo on constate que les émissions biogéniques (comme celle du formaldéhyde, H2CO) liées en particulier aux cycles annuels de la forêt tropicale, sont parmi les plus élevées du globe (De Smedt et al., 2015). Les mesures des instruments MAX-DOAS(differential optical absorption spectroscopy), CIMEL et la station météo de Bujumbura (Burundi) confirment aussi que l’atmosphère de Bujumbura est influencée par les émissions biogéniques de H2CO en provenance du Congo (Gielen et al., 2017), même si elle est relativement éloignée du maximum d’émission, situé plus à l’Ouest au Congo.
Dans le présent séminaire, nous avons donc montré la conception et le test d’un instrument MAXDOAS qui sera installé à Kinshasa le mois de Juin 2019. Nous avons aussi montré le fonctionnement et le résultat de l’ancien instrument installé à Kinshasa depuis Mai 2017. Les résultats préliminaires des observations à Kinshasa ont été montré aussi en comparaison avec les observations satellite (OMI) et les extractions de la simulation GEOS-CHEM(Goddard Earth Observing System) pour l’année 2017.Projet KinAER
ATMOSPHERIC POLLUTION IN KINSHASA
No full textThe capital of the Democratic Republic of Congo is one of the major African cities without an air quality monitoring network. Yet several publications seem to confirm the deterioration of air quality in Kinshasa. In this work, we present a first study conducted in Kinshasa, based on remote atmospheric observation of trace gases such as nitrogen dioxide.ISWI-MAGHREB-AFRIQUE DE L'OUEST (IMAO
First MAX-DOAS observations of tropospheric NO2 and H2CO in Central Africa: impact on air quality and validation of the TROPOMI satellite instrument
No full textThis thesis addresses air pollution in Central Africa, with a focus on nitrogen dioxide (NO2), formaldehyde (H2CO), and aerosol pollution. Recent studies, utilizing satellite observations, reveal peaks in these pollutants, primarily attributed to biogenic emissions from the region's extensive forests, but also from biomass burning, forest fires, and charcoal production. The lack of ground-level measurements in Central Africa is emphasized.
The thesis operationalizes a remote sensing instrument based on Differential Optical Absorption Spectroscopy (DOAS) in Kinshasa. Data collected from May 2017 to July 2021 establish a pollution database, revealing significant levels of NO2, H2CO, and aerosols, particularly during the dry season. Daily cycles are identified, showing elevated levels around noontime.
Initial validation exercises of the TROPOMI satellite instrument demonstrate good agreement with ground observations, considering corrections based on the use of more representative MAX-DOAS measured profile as a priori information in the TROPOMI product. Evaluation of the GEOS-Chem model indicates its accuracy in replicating real atmospheric conditions, emphasizing the significant impact of biomass burning on NO2 and H2CO pollution.
This work underscores the need for more ground instruments in the sub-region. The need to inform the population is emphasized, as is the definition of effective measures to reduce pollution levels
Measurement of the tropospheric vertical columns of NO2 and H2CO over Kinshasa: comparison with TROPOMI and the GEOS-Chem model/Poster
No full textMany African cities are affected by the problem of air pollution as mentioned in
the study by Louisse et al 2014 stating that air quality in African urban areas is
expected to deteriorate in the coming decades.
The city of Kinshasa, the capital of the Democratic Republic of Congo (DRC), a
large megalopolis of 12 million inhabitants, with an estimated population of 30
million by 2030 UN (2016), is not spared by this air pollution as shown in
McFarlane et al. (2020) and WHO reports. It is dominated by a multiplication of
motorcycles, old vehicles, open garbage cans, unpaved roads and the use of
embers from forest wood as energy for cooking. Its surroundings are also affected
by seasonal forest burning, which is a potential source of several pollutants,
including NO2 and H2CO.
However, measurements are lacking, and this limits the number of studies address
this topic in this region of the world. Even with regard to the worldwide
distribution of atmospheric measurement stations (e.g. via the NDACC network
www.ndacc.org), it can be seen that Central Africa is largely under-sampled
compared to other land areas of the globe. Although satellite observations exist in
this region, they are generally unsuitable for sampling over heavily polluted areas
due to their low sensitivity near the surface, and the consequences can be directly
related to the inaccuracy of the corresponding emission estimates by top-down
approaches. Ground-based measurements are and will remain essential for
atmospheric research, whatever the future progress of satellite instruments and
the refinement of models. Therefore, measurements in this region are of particular
interest in order to know the temporal and spatial distribution of NO2 and H2CO
emission intensity at the local scale and also in order to understand the accuracy
of satellites and models.
It is in this perspective that the present work is inscribed, with the objective of
presenting a series of atmospheric measurements of NO2 and H2CO, going from
November 2019 to July 2021, with as vision: 1. to make a validation of the
TROPOMI satellite, 2. to evaluate the performance of the GEOS-Chem model to
constrain the emissions in this area
Télédétection de la pollution en dioxyde d'azote et en formaldéhyde dans l'atmosphère de Kinshasa à partir d'une station de mesure des polluants atmosphériques
No full textNational audienceWe present in this article the fruit of a collaborative effort between the University of Kinshasa through the Department of Physics of the Faculty of Sciences and the UV-Visible group of the Royal Belgian Institute for Space Aeronomy (BIRA-IASB). This collaboration in its first phase resulted in the installation of an optical remote sensing instrument for measuring air pollutants in the Kinshasa atmosphere. Kinshasa, the capital of the Democratic Republic of Congo "DRC", the third largest city in Africa with about 10 million inhabitants, is the source of significant emissions from various pollutants. In this study, we use a remote sensing instrument to measure the abundance of two important gaseous pollutants: dioxide (NO2) and formaldehyde (H2CO) present in the Kinshasa atmosphere. The deployed equipment is based on a commercial grating spectrometer covering the spectral range from 290 to 450 nm, and connected by an optical fiber to record the sky light. A GPS system is integrated into the instrument, allowing for mobile measurements from a vehicle. The control of all the interconnected modules is ensured by a computer running Windows. The different measurements made by the equipment are analyzed and processed by the DOAS "Differential Optical Absorption Spectroscopy" technique. Since the installation of this station in May 2017, we have been able to build a database of several months of measurements that we use to look for trace gas concentrations. Results are analysed for tropospheric NO2 and H2CO signals as well as for stratospheric NO2, the latter being identified in twilight measurements. The system is also shown to allow for stratospheric ozone detection.Nous présentons dans cet article le fruit d’une collaboration entre l’Université de Kinshasa à travers le Département de physique de la Faculté des sciences et le groupe UV-Visible de l’Institut Royal d’Aéronomie Spatiale de Belgique (BIRA-IASB). Cette collaboration dans sa première phase a abouti à l’installation d’un instrument optique de télédétection pour mesurer les polluants atmosphériques dans l’atmosphère de Kinshasa. Kinshasa, la capitale de la République démocratique du Congo "La RDC", troisième ville d’Afrique avec environ 10 millions d’habitants, est à l’origine de nombreuses émissions de polluants. Dans cette étude, nous utilisons un instrument de télédétection pour mesurer l'abondance de deux polluants gazeux importants: le dioxyde (NO2) et le formaldéhyde (H2CO) présents dans l'atmosphère de Kinshasa. L'équipement déployé est basé sur un spectromètre à réseau commercial couvrant la gamme spectrale de 290 à 450 nm, et connecté par une fibre optique pour enregistrer la lumière du ciel. Un système GPS est intégré à l'instrument, permettant des mesures mobiles à partir d'un véhicule. Le contrôle de tous les modules interconnectés est assuré par un ordinateur fonctionnant sous Windows. Les différentes mesures effectuées par les équipements sont analysées et traitées par la technique DOAS "Spectroscopie d'absorption optique différentielle". Depuis l'installation de cette station en mai 2017, nous avons pu constituer une base de données de plusieurs mois de mesures que nous utilisons pour rechercher des concentrations des gaz en traces. Les résultats sont analysés pour les signaux troposphériques de NO2 et de H2CO ainsi que pour les signaux stratosphériques de NO2, ce dernier étant identifié dans les mesures de crépuscule. Le système permet également de détecter l’ozone stratosphérique
Mon- itoring of air quality in Kinshasa by mobile analyses of atmospheric NO2 in different geographical locations
No full textpeer reviewedThis study addresses the issue of air quality in the city of Kinshasa, capital of the Democratic Republic of Congo (DRC). It is based on the study of the spatial distribution of trace species such as NO2 and CO in this city. The two species targeted in this study are major contributors to air quality degradation as promulgated by the World Health Organization. Real-time monitoring of the chemical concentration of these species is strongly recommended. Raw data were collected over a three-day period, using mobile measurements from a car. The chemical concentration of NO2 was sampled using DOAS (Differential Optical Absorption Spectroscopy) and its spatial distribution was achieved using GPS surveys. The NO2 concentration measurements are valid over a distance covering a radius of 1 km from each sampling point. The result of this study showed that the communes of Limete and Gombe (heavy goods vehicle section) are much more affected by NO2 pollution, followed by the large crossroads with intense commercial activity zones such as in the commune of Mont ngafula (Matadi mayo market) or at the Ngaba traffic circle. The concentration of CO was taken thanks to a LOW Cost sensor, giving in situ measurements. As the instrument used was of low accuracy, quantitative analysis of CO was not performed. Nevertheless, the CO signal was detected in almost all the communes of the city of Kinshasa
MAX-DOAS measurements of NO2 and H2CO in the city of Kinshasa from 2019 2020
No full textThe first MAX-DOAS measurements of NO2 and H2CO were presented in this study. A preliminary comparison with TROPOMI is also presente
DOAS measurements of NO2 and H2CO at Kinshasa and Comparisons with Satellites Observations
No full textAfrica experiences a fast urban inhabitants growth, caused by the largest population boom in the world, combined with rural exodus. Many cities are heavily affected by air pollution. It is therefore essential to monitor the concentrations of the various polluting species such as NO2, HCHO, O3 and aerosols, which have a direct impact on the population health. The sources of pollutant in Africa are different from those found in Europe. For example, forest fires and household cooking largely contribute to the NO2 and HCHO burdens in Central Africa. However, many large African cities, such as the City of Kinshasa, capital of the Democratic Republic of Congo, do not have atmospheric measurement instruments.
In order to tackle the lack of measurements in Kinshasa, the Royal Belgian Institute of Space Aeronomy (BIRA-IASB) has, in collaboration with the University of Kinshasa (UniKin), installed an optical remote sensing instrument on the UniKin site (-4.42°S, 15.31°E). Installed in May 2017, the instrument has been in operation until today and provides data to measure the column amounts of several polluting species in the atmosphere of Kinshasa. The instrument is based on a compact AVANTES spectrometer covering the spectral range 290 - 450 nm with 0.7 nm resolution. The spectrometer is a Czerny-Turner type with an entry slit of 50 μm wide, and an array of 1200 l/mm. A 10 m long and 600 μm diameter optical fiber is connected to the spectrometer to receive the incident light beam from the sky. Measurements were mainly made by looking in a fixed direction until November 2019. Since then, a Multi-Axis geometry (MAX-DOAS) has been implemented.
The measurements provided by this DOAS instrument allowed us to start studying the atmosphere of Kinshasa using the QDOAS software, which allows us to find the oblique columns of different observed species. This poster will present the instrument, the database and the procedure used to convert these oblique columns into vertical columns, using the air mass factors calculated with the radiative transfer model. We also present our first MAX-DOAS results, analyzed using the retrieval tools of the ESA FRM4DOAS project. The study of current results clearly shows the signature of polluting species such as NO2, HCHO in the atmosphere of Kinshasa. We also use simulations by the GEOS-Chem chemistry transport model to evaluate the magnitude of the emissions needed to explain the observed column amounts. These observations made in Kinshasa could contribute to the validation of satellite products and the refinement of models. We present a first comparison of Kinshasa's ground-based observations with those of the OMI and TROPOMI satellitesEmissions biogéniques dans le bassin du Congo, impact sur la qualité de l'air en Afrique Centrale et sur la validation de l'instrument Tropomi à bord du satellite SP
