Estimation of ship emission rates at a major shipping lane by long-path DOAS measurements

Abstract

Abstract. Ships are an important source of SO2 and NOx, which are key parameters of air quality. Monitoring of ship emissions is usually carried out using in situ instruments on land, which depend on favourable wind conditions to transport the emitted substances to the measurement site. Remote sensing techniques such as long-path differential optical absorption spectroscopy (LP-DOAS) measurements can supplement those measurements, especially in unfavourable meteorological conditions. In this study 1 year of LP-DOAS measurements made across the river Elbe close to Hamburg (Germany) have been evaluated. Peaks (i.e. elevated concentrations) in the NO2 and SO2 time series were assigned to passing ships, and a method to derive emission rates of SO2, NO2 and NOx from those measurements using a Gaussian plume model is presented. A total of 7402 individual ship passages have been monitored, and their respective NOx, SO2 and NO2 emission rates have been derived. The emission rates, coupled with the knowledge of the ship type, ship size and ship speed, have been analysed. Emission rates are compared to emission factors from previous studies and show good agreement. In contrast to emission factors (in grams per kilogram fuel), the derived emission rates (in grams per second) do not need further knowledge about the fuel consumption of the ship. To our knowledge this is the first time emission rates of air pollutants from individual ships have been derived from LP-DOAS measurements.

Determination of NOx emission rates of sailing inland ships from on-shore measurements

“…The improved algorithm presented here, has several advantages over the method described in Krause et al (2021), where a…”

“…This means that NO x emission rates can be derived from existing stations with little additional costs. In addition, in-situ measurement stations are able to measure NO and NO 2 simultaneously, so that NO x can be measured directly and has not to be inferred from NO 2 observations as in Krause et al (2021).…”

“…Shipping emission have been typically investigated using in situ instruments, either on-board or on-shore (e.g., Moldanová et al, 2009;Alföldy et al, 2013;Diesch et al, 2013;Beecken et al, 2014;Pirjola et al, 2014;Beecken et al, 2015;Kattner et al, 2015;Kurtenbach et al, 2016;Kattner, 2019;Ausmeel et al, 2019;Celik et al, 2020;Walden et al, 2021). Additionally, remote sensing techniques such as differential optical absorption spectroscopy (DOAS) (e.g., Berg et al, 2012;Seyler et al, 2017Seyler et al, , 2019Cheng et al, 2019;Krause et al, 2021) and more recently UAVs are used to investigate ship emissions (Zhou et al, 2019(Zhou et al, , 2020. The long term impact of shipping emissions has been investigated by modelling studies (Eyring et al, 2005;Ramacher et al, 2018Ramacher et al, , 2020Tang et al, 2020;Wang et al, 2021;Jiang et al, 2021).…”

“…In addition, a method to derive absolute NO x emission rates from on-shore measurements has been developed and is presented in this study. The retrieval concept builds on the approach presented in Krause et al (2021), but the method has been improved and the algorithm can now be used with data measured by any standardized in-situ measurement station located in the vicinity of a river.…”

Determination of NOx emission rates of inland ships from onshore measurements

“…Additionally, remote sensing techniques such as differential optical absorption spectroscopy (DOAS; e.g. Berg et al, 2012;Seyler et al, 2017Seyler et al, , 2019Cheng et al, 2019;Krause et al, 2021) and more recently unmanned aerial vehicles (UAVs) are used to investigate ship emissions (Zhou et al, 2019(Zhou et al, , 2020. In most studies, ship emissions are investigated only for short time periods or only specific ships are investigated.…”