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Atmos. Chem. Phys., 15,10087-10092, 2015 
www.atmos-chem-phys.net/15/10087/2015/ 
tent allowed in HFOs was capped at 4.5 %, and after 2012 
this limit was reduced to 3.5 %. In addition, so-called “Sul 
fur Emission Control Areas” (SECA) were established with 
an even further reduced sulfur limit. One SECA is along the 
North American coast, and another one comprises the Baltic 
Sea and the North Sea up to the Shetland Islands and to the 
western entrance of the English Channel. Within these SE- 
CAs the sulfur limit was initially set to 1.5 %, which was 
reduced to 1.0% in 2010 and has now reached its current 
reduction step in January 2015 with a limit of 0.1 %. 
While the 1 % limit could still be met with sulfur-reduced 
HFO, the new regulation forces ships to either use more ex 
pensive alternatives such as marine gas oil (MGO), or ultra- 
low sulfur HFO, or consider reconstruction to enable the use 
of alternative fuel such as liquefied natural gas (LNG) or 
methanol. As an alternative technology, the operation of ex 
haust gas cleaning systems (scrubbers) is also permitted, as 
long as it provides the same level of protection against sulfur 
dioxide emissions as the use of low sulfur fuel. These alter 
native options have been deployed to some ships and first 
studies have documented their effectiveness and economic 
efficiency (Reynolds, 2011; Jiang et al., 2014), but they are 
still under development and not very widespread, and for the 
vast majority of ships, the only option to meet the regulations 
is to use desulfurised fuel. 
With the regulations in place, the question remains on how 
to efficiently verify compliance of the ships. To date, compli 
ance is checked by inspection authorities who enter ships at 
berth, review fuel log books and fuel quality certificates and, 
if suspicion is raised, take a fuel sample to be analysed at 
certified laboratories. With the results of these analyses, it is 
possible to verify compliance and if needed, take legal ac 
tion. However, these controls can check just a minor number 
of ships. It is also not possible to evaluate the performance 
and compliance of scrubber technology by sulfur prediction 
in bunker oil samples which would be problematic if this 
method becomes more popular and common in future. An 
other problem is to control ship fuel of ships on the open sea. 
For these reasons, several studies have suggested the im 
plementation of air quality measurement systems especially 
aiming at the surveillance of ship emissions. One simple but 
efficient method is direct and simultaneous measurements of 
pollution trace gases with in situ instruments. These instru 
ments can quite easily be adapted to measurement conditions 
on aeroplanes, research vessels and trucks and have been 
used in a variety of campaigns in recent years (Sinha et al., 
2003; Schlager et al., 2006; Agrawal et al., 2009; Williams 
et al., 2009; Diesch et al., 2013; Balzani Loov et al., 2014; 
Beecken et al., 2015). Based on the experience from those 
studies, we have established a measurement station near the 
harbour of Hamburg to monitor ship emissions, in order to 
estimate sulfur contents of fuel on board of passing individ 
ual ships. Our ship emissions data set from September 2014 
to January 2015 documents the quality of implementation of 
the MARPOL VI regulation with respect to compliant sul- 
Figure 1. Location of the measurement station on the northern bank 
of the river Elbe, near Hamburg harbour. On the right: picture of 
instrument box. Map source: OpenStreetMap. 
fui' content in shipping fuel used in SECAs and follows the 
recent strong tightening of the regulation on 1 January 2015. 
2 Measurement site and methods 
The measurements reported here were conducted as part of 
the Mesmart project, a cooperation between the University of 
Bremen and the German Federal Maritime and Hydrographic 
Agency. 
2.1 Measurement site 
Hamburg harbour is the third largest harbour in Europe and 
the 14th largest worldwide. In 2014, it had a 20-foot standard 
container throughput of 9.7 billion containers according to 
Hamburg port statistics. On average there are 800 calls per 
month, of which more than half are container vessels, and 
the other half consists mainly of reefer vessels, tankers and 
bulk carriers. The harbour is located at the mouth of the river 
Elbe about 110 km inland; see Fig. 1. 
Measurements were conducted next to the river Elbe in 
the town of Wedel, which is near Hamburg, on the property 
and with the support of the Waterways and Shipping Office 
Hamburg. The instruments were set up right at the northern 
banks of the Elbe, with an approximate line of sight distance 
to ships leaving and entering Hamburg harbour of 0.3 and 
0.5 km respectively. The average main wind direction at this 
location has a southerly component, so for most of the time 
within the measurement period, the exhaust plumes of the 
ships were blown to the instruments. The area in the main 
wind direction south of the measurement station and the Elbe 
is rural and sparsely populated with no significant sources of 
air pollution. Thus the location of the monitoring site is opti 
mal for relatively low background concentrations of nitrogen 
oxides (NO T ) and SOt. 
2.2 Instrumentation 
The concentrations of SOt, NO,, COt and ozone (O3) were 
measured continuously with individual instruments, which 
were combined in a temperature-stabilised box to ensure sta-