The C-130 is large four-engined former transport aircraft operated by the Meteorological Research Flight (MRF), with an RAF crew. It has a maximum range of 5,000 km which, flying from its usual home base at Boscombe Down, Wiltshire, can reach the North Atlantic almost as far as Iceland. Its range can be increased by deploying it to other air bases.
The aircraft was instrumented in a number of different configurations, which were customised for the various ACSOE campaigns. A large number of continuous instruments can were housed inside the aircraft, taking air from a number of air inlets. High volume pumping systems were fitted to allow aerosol samples to be collected on filter packs, and whole air samples in stainless steel flasks, for later analysis. Radiometers, both upward and downward looking, were fitted to the exterior of the aircraft. A full suite of aircraft instrument data was also available. Communication with the ground was possible via marine band radio, FAX and email. A central data acquisition system (DRS) logged data from all instruments. An on board computer (HORACE) enabled the data to be viewed in real time for simple plots to be constructed and even for simple chemical algorithms to be computed for various chemical parameters. This gave flight scientists an instantaneous view of the conditions encountered and informed decisions on the flight plan were made. As part of the ACSOE airborne campaigns, detailed meteorological information - including synoptic charts and trajectories (fore-, now- and hind-casting; forward and backward) were supplied by the MRF for both phases, planning and post-experiment interpretative purposes. The MRF was also fully collaborate scientifically with MRF personnel being involved in making airborne measurements (such as PAN, ozone, aerosols, flask sampling, etc.), and participating in the data reduction and interpretation phases.
| Max. duration: | 12h |
| Range: | 5,000 km |
| Ceiling: | 10,000 km/h |
| Minimum operational altitude: | 50m |
| Operational speed: | 270-540 km/h |
| Aircraft crew: | 2 x pilots, navigator, engineer, loadmaster |
| Scientific crew: | up to 12 |
| Available power for instruments: | 21 kW |
The C-130 was successfully used in an EC-funded Oxidising Capacity of the Tropospheric Atmosphere (OCTA) project (a forerunner to ACSOE). Several new instruments were constructed for the C-130 after OCTA to be used during ACSOE. The C-130 the became one of the most comprehensively equipped aircraft for studies of tropospheric chemistry in the world.
New instrumentation included a 4-channel ‘NOxy’ system capable of measuring NO, NO2, NOy and NOy-HNO3 simultaneously with detection limits varying from 1 pptv in 1 sec for NO to 5 pptv in 1 sec for NO2. A formaldehyde instrument with a detection limit in the range of 50 pptv for continuous operation was constructed and the peroxide instrument was modified to measure both H2O2 and RO2H. A TDLAS system was purchased to measure NO2 and formaldehyde with a detection limit of the order of 50 pptv for 1 min integration time. The PAN instrument was improved such that its sensitivity approaches 10 pptv. Also a new pump was installed which enabled the collection of filter samples with a higher frequency. Instruments that were under development included a PERCA to measure peroxy radicals, and a radiometer to measure J(O1D).
The Jetstream is a twin turbo-prop aircraft with a more limited range than the C-130. It is owned and operated by the Cranfield Institute for Technology. In ACSOE it flew with an Imperial College (ACRU) scientific crew and instrument package. The ACRU package included a range of continuous chemical analysers for nitrogen species, peroxide, sulphur dioxide, PAN, cloud/rain water major ions, and ozone. A suite of standard physical parameters were also logged, including broad band radiometers. Grab samples of whole air, filter samples, and denuder samples were collected for post-flight chemical analysis of gases, particles, and adsorbed acidic gases.
| Endurance: | 2.5 - 4 h depending on payload |
| Range: | 1100 km |
| Ceiling: | 7600 m (pressurised) |
| Speed: | 200 -330 km/h |
| Instrument capacity: | 480 kg |
| Aircrew: | 2 |
| Observers: | 2 - 4 (depending on load) |
| Power: | 2 kVA at 50 Hz (115 or 240 V), 4 kVA at 400 Hz (200 V), 60 A at 28 V DC |