Static Source Error Calibration of a Nose Boom Mounted Air Data System on an Atmospheric Research Aircraft Using the Trailing Cone Method

This work demonstrates the calibration of an experimental air data probe on an atmospheric research aircraft by means of the Trailing Cone method. The probe under investigation is located on a nose boom in order to minimize the aerodynamic influence of the fuselage on the pressure measurement ahead of the aircraft. However, the data from this experiment proves that this configuration is still subject to significant pressure deviations from the undisturbed atmospheric values. This work demonstrates the determination of this error and presents an appropriate parameterization of the data which is prerequisite to provide accurately corrected pressure readings from this sensor. The experiment covers the determination of the proper configuration (length) for the Trailing Cone assembly, the validation of the method itself and the subsequent calibration of the air data sensor. Several improvements were applied to the Trailing Cone method in order to reduce the flight test effort as well as to significantly enhance the accuracy of the method itself. As a consequence a total of only three test flights was necessary to validate the method and to calibrate the air data sensor. The data analysis shows that the accuracy of the Trailing Cone reference measurement is very close to the pressure sensor calibration limit of 0.1hPa. The resulting accuracy of the corrected pressure measurement by the nose boom mounted pressure probe was demonstrated to be about 0.2 hPa, which represents the 3σ value

Static Source Error Calibration of a Nose Boom Mounted Air Data System on an Atmospheric Research Aircraft Using the Trailing Cone Method

This work demonstrates the calibration of an experimental air data probe on an atmospheric research aircraft by means of the Trailing Cone method. The probe under investigation is located on a nose boom in order to minimize the aerodynamic influence of the fuselage on the pressure measurement ahead of the aircraft. However, the data from this experiment proves that this configuration is still subject to significant pressure deviations from the undisturbed atmospheric values. This work demonstrates the determination of this error and presents an appropriate parameterization of the data which is prerequisite to provide accurately corrected pressure readings from this sensor. The experiment covers the determination of the proper configuration (length) for the Trailing Cone assembly, the validation of the method itself and the subsequent calibration of the air data sensor. Several improvements were applied to the Trailing Cone method in order to reduce the flight test effort as well as to significantly enhance the accuracy of the method itself. As a consequence a total of only three test flights was necessary to validate the method and to calibrate the air data sensor. The data analysis shows that the accuracy of the Trailing Cone reference measurement is very close to the pressure sensor calibration limit of 0.1hPa. The resulting accuracy of the corrected pressure measurement by the nose boom mounted pressure probe was demonstrated to be about 0.2 hPa, which represents the 3σ value

Continuous condensation particle (CP) observations from 1984 through 2009 at Neumayer Station, Antarctica

Continuous condensation particle (CP) observations were conducted from 1984 through 2009 at Neumayer Station under stringent contamination control. During this period, the CP concentration (median 258 1/cm**3) showed no significant long term trend but exhibited a pronounced seasonality characterized by a stepwise increase starting in September and reaching its annual maximum of around 10**3/cm**3 in March. Minimum values below 10**2/cm**3 were observed during June/July. Dedicated time series analyses in the time and frequency domain revealed no significant correlations between inter-annual CP concentration variations and atmospheric circulation indices like Southern Annular Mode (SAM) or Southern Ocean Index (SOI). The impact of the Pinatubo volcanic eruption and strong El Niño events did not affect CP concentrations. From thermodenuder experiments we deduced that the portion of volatile (at 125 °C) and semi-volatile (at 250 °C) particles which could be both associated with biogenic sulfur aerosol, was maximum during austral summer, while during winter non-volatile sea salt particles dominated. During September through April we could frequently observe enhanced concentrations of ultrafine particles within the nucleation mode (between 3 nm and 7 nm particle diameter), preferentially in the afternoon

Pollution slightly enhances atmospheric cooling by low-level clouds in tropical West Africa

International audienceReflection of solar radiation by tropical low-level clouds has an important cooling effect on climate and leads to decreases in surface temperatures. Still, the effect of pollution on ubiquitous tropical continental low-level clouds and the investigation of the related impact on atmospheric cooling rates are poorly constrained by in-situ observations and modelling, in particular during the West African summer monsoon season. Here, we present comprehensive in-situ measurements of 20 microphysical properties of low-level clouds over tropical West Africa, measured with the DLR aircraft Falcon 20 during the DACCIWA (Dynamics-Aerosol-Chemistry-Cloud Interactions in West Africa) campaign in June and July 2016