The Meteorological Research Flight (MRF) was a Met Office facility, which flew a well-instrumented C-130 Hercules aircraft for atmospheric research purposes.

This dataset contains airborne atmospheric and chemistry measurements taken on board the Met Office C-130 Hercules aircraft flight A755 for the Atmospheric Chemistry and Transport of Ozone in the upper troposphere-lower stratosphere (UTLS) (ACTO) campaign. The flight was located over the North Atlantic.

The purpose of the flight was to investigate a dry slot behind a cold front to the North West of Scotland. Many interesting filaments of air were sampled. However, distinct 'stratospheric' filaments were not observed until the end of the flight.

After the initial end of science an interesting filament was sampled with high ozone (around 130ppb). We retraced our steps in order to fly through once more at science speed. This filament, at FL150, was further east than the forecast 'stratospheric air' filaments.

When the air of stratospheric origins was sampled it was found to have high ozone / low relative humidity as expected but it should be noted that there was also high PAN and slightly elevated black carbon.

The instruments generally worked well. The FWVS had to have the odd adjustment in flight and then found to maintain a good correlation with the GE; the peroxide began to loose flow at around FL245 and the CO was found to have a small leak of cabin air, which was corrected by 13:50. The CO was also found to be influenced by the flow through the PSAP. The CO did not show much structure during the flight until near the end when the air with stratospheric characteristics was observed.

Meteorology

An anticyclone was centred to the east of the North Sea and a waving front positioned to approximately along 7 west. The frontal cloud was quite apparent on the way to the operational area. However, a flight level (FL140) was found above most of the cloud, for the NOxy calibrations. Once past the frontal cloud there was little cloud in the operational area: just some thin cirrus.