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Jos

5 records found

Authored

Current potential of CH4 emission estimates using TROPOMI in the Middle East

Journal article (2024) - Mengyao Liu, Ronald van der A, Michiel van Weele, Lotte Bryan, Henk Eskes, j. Pepijn Veefkind, j. Pepijn Veefkind, Yongxue Liu, Xiaojuan Lin, Xiaojuan Lin, Jos de Laat, Jieying Ding

An improved divergence method has been developed to estimate annual methane (CH4) emissions from TROPOspheric Monitoring Instrument (TROPOMI) observations. It has been applied to the period of 2018 to 2021 over the Middle East, where the orography is complicated, and the mean mixing ratio of methane (XCH4) might be affected by albedos or aerosols over some locations. To adapt to extreme changes of terrain over mountains or coasts, winds are used with their divergent part removed. A temporal filter is introduced to identify highly variable emissions and to further exclude fake sources caused by retrieval artifacts. We compare our results to widely used bottom-up anthropogenic emission inventories: Emissions Database for Global Atmospheric Research (EDGAR), Community Emissions Data System (CEDS), and Global Fuel Exploitation Inventory (GFEI) over several regions representing various types of sources. The NOx emissions are from EDGAR and Daily Emissions Constrained by Satellite Observations (DECSO), and the industrial heat sources identified by Visible Infrared Imaging Radiometer Suite (VIIRS) are further used to better understand our resulting methane emissions. Our results indicate possibly large underestimations of methane emissions in metropolises like Tehran (up to 50 %) and Isfahan (up to 70 %) in Iran. The derived annual methane emissions from oil/gas production near the Caspian Sea in Turkmenistan are comparable to GFEI but more than 2 times higher than EDGAR and CEDS in 2019. Large discrepancies in the distribution of methane sources in Riyadh and its surrounding areas are found between EDGAR, CEDS, GFEI, and our emissions. The methane emission from oil/gas production to the east of Riyadh seems to be largely overestimated by EDGAR and CEDS, while our estimates as well as GFEI and DECSO NOx indicate much lower emissions from industrial activities. On the other hand, regions like Iran, Iraq, and Oman are dominated by sources from oil and gas exploitation that probably include more irregular releases of methane, with the result that our estimates, which include only invariable sources, are lower than the bottom-up emission inventories.@en

A New Divergence Method to Quantify Methane Emissions Using Observations of Sentinel-5P TROPOMI

Journal article (2021) - Mengyao Liu, Ronald van der A, Ronald van der A, Michiel van Weele, Henk Eskes, Xiao Lu, j. Pepijn Veefkind, j. Pepijn Veefkind, Jos de Laat, Hao Kong, Jingxu Wang, None More Authors

We present a new divergence method to estimated methane (CH₄) emissions from satellite observed mean mixing ratio of methane (XCH₄) by deriving the regional enhancement of XCH₄ in the Planetary Boundary Layer (PBL). The applicability is proven ...

Systematic Detection and Correction of Instrument-Related Time Shifts Using Seismic Interferometric Surface Waves

Conference paper (2018) - Jos de Laat, Jos de Laat, C. Weemstra, C. Weemstra, A. Verdel, P. Jousset, Gylfi Páll Hersir, Hanna Blanck

Timing errors are a notorious problem in seismic data acquisition and processing. A technique is presented that allows such time shifts to be detected and corrected in a systematic fashion. The methodology relies on virtualsource responses retrieved through the application of sei ...

The Ozone Monitoring Instrument

Overview of 14 years in space

Review (2018) - Pieternel Felicitas Levelt, Pieternel Felicitas Levelt, Joanna Joiner, Chris A. McLinden, Vitali E. Fioletov, Simon Carn, Jos de Laat, Matthew Deland, Sergey V. Marchenko, Richard McPeters, Jerald Ziemke, Jerald Ziemke, Dejian Fu, Xiong Liu, Johanna Tamminen, Kenneth Pickering, Kenneth Pickering, Arnoud Apituley, Gonzalo González Abad, A. Arola, K. Folkert Boersma, K. Folkert Boersma, Christopher Chan Miller, K. Chance, M. de Graaf, Janne Hakkarainen, Seppo Hassinen, j. Pepijn Veefkind, j. Pepijn Veefkind, Iolanda Ialongo, Quintus Kleipool, Nickolay A. Krotkov, Can Li, Lok N. Lamsal, Paul Newman, C. R. Nowlan, R. M. Suleiman, Lieuwe Gijsbert Tilstra, Omar Torres, Pawan K. Bhartia, Huiqun Wang, Krzysztof Wargan, Krzysztof Wargan, Deborah C. Stein Zweers, Bryan N. Duncan, David G. Streets, Henk Eskes, Ronald A. Van Der

This overview paper highlights the successes of the Ozone Monitoring Instrument (OMI) on board the Aura satellite spanning a period of nearly 14 years. Data from OMI has been used in a wide range of applications and research resulting in many new findings. Due to its unprecede ...

Contributed

Exploring TROPOMI NO₂ observations over low clouds and fog

Understanding the impact of the air-mass factor on cloudy scenes over the North Sea

Master thesis (2024) - N. Van der Borght, j. Pepijn Veefkind, J. Timmermans, Jos de Laat

This thesis investigates TROPOMI NO₂observations over low clouds and fog. Such scenes present unique opportunities due to the increased reflectivity of clouds in the lower troposphere, which enhances sensor sensitivity. However, in order to accurately estimate vertical NO₂density in these scenarios, a better understanding of the retrieval process in such conditions is imperative. Two NO₂retrieval case studies, both exhibiting a spurious retrieval in the presence of low clouds and fog above the North Sea, are examined: February 14𝑡ℎ, 2023, and April 9𝑡ℎ, 2023. The main focus was on the influence of the air-mass factor on the retrieval. This factor converts measured slant column data along the satellite path into vertical tropospheric columns. Spurious spatial patterns are strongly amplified after the application of the air-mass factor. Key dependencies influencing the conversion from slant to
vertical column are identified, being the the a-priori NO₂profile, air mass factor calculation, and cloud characterization. Notably, the low spatial resolution of the a-priori model and its pronounced peak near the surface contribute to inflated NO₂values over clouds. The majority of the a-priori NO₂profile is simulated underneath the cloud field, leading the retrieval algorithm to assume it did not capture a significant portion of the concentration, thus strongly increasing retrieved NO₂ densities over clouds. Furthermore, spatial reflectivity patterns in the North Sea are not always accounted for in the surface reflectivity climatology. This results in misinterpreted clouds with a low cloud fraction. Misinterpreted clouds over open sea areas, combined with low cloud pressures, result in downward corrections over clear-sky seas. These effects culminate in an exacerbated cloudy-clear contrast in NO₂densities, aligning with the outlines of low cloud fields. Additionally, the heterogeneous cloud field challenges the assumption of a fixed-height, fixed-albedo Lambertian reflector. This inflation effect is modulated by the cloud height. The uncertain height of the Lambertian cloud in the lowest troposphere, combined with an assumed NO₂profile at the same height, dominates the air-mass factor calculation . Four recommendations to enhance NO₂retrieval accuracy in the presence of low clouds and fog over the North Sea are presented, which include a Cloud-as-Layers characterization, high-resolution simulations and in-situ measurements of vertical NO₂profiles in the presence of low clouds, an a-priori correction of the NO₂profile in the presence of low clouds and implementing auxiliary data relating to spatial patterns in sea-colour of the North Sea.

Jos