Aircraft type‐specific errors in AMDAR weather reports from commercial aircraft

Abstract

AMDAR (Aircraft Meteorological DAta Relay) automated weather reports from commercial aircraft provide an increasing amount of input data for numerical weather prediction models. Previous studies have investigated the quality of AMDAR data. Few of these studies, however, have revealed indications of systematic errors dependent upon the aircraft type. Since different airlines use different algorithms to generate AMDAR reports, it has remained unclear whether a dependency on the aircraft type is caused by physical properties of the aircraft or by different data processing algorithms. In the present study, a special AMDAR dataset was used to investigate the physical type-dependent errors of AMDAR reports. This dataset consists of AMDAR measurements by Lufthansa aircraft performing over 300 landings overall at Frankfurt Rhein/Main (EDDF/FRA) on 22 days in 2004. All of this data has been processed by the same software, implying that influences from different processing algorithms should not be expected. From the comparison of single descents to hourly averaged vertical profiles, it is shown that temperature measurements by different aircraft types can have systematic differences of up to 1 K. In contrast, random temperature errors of most types are estimated to be less than 0.3 K. It is demonstrated that systematic deviations in AMDAR wind measurements can be regarded as an error vector, which is fixed to the aircraft reference system. The largest systematic deviations in wind measurements from different aircraft types (more than 0.5 m s −1 ) were found to exist in the longitudinal direction (i.e. parallel to the flight direction).

Systematic Differences in Aircraft and Radiosonde Temperatures

“…One type, Airbus A318-100, has an atypical pattern with ascent MTOI colder than descent (not shown). Recently, Drue et al (2008) found that different Lufthansa aircraft types showed average temperature differences by collocations for descending aircraft at the Frankfurt airport as large as 1°C, even though the aircraft all had the same software for processing the temperature measurements and had comparable environmental conditions. Computing MTOI for all aircraft types for different POF to the nearest mandatory pressure levels would lead to problems with very low counts for some types.…”

Evaluation of Accuracy of Chinese AMDAR Data for 2015

“…Ballish and Kumar (2008) found an overall positive bias in aircraft temperature observations when compared to radiosonde observations. Meanwhile, systematic differences in temperature observations exist between different aircraft types (Drüe et al 2008). Zhu et al (2015) has indicated that the aircraft ascent/ descent rate can be used to correct biases in temperature observations.…”

The future of Earth observation in hydrology

“…While observations from dedicated aircraft are typically only collected during sensor testing and infrequent, targeted measurement campaigns, there is little to inhibit (at least from a scientific perspective) airborne sensors from hitching rides aboard commercial aircraft, greatly expanding their spatial and temporal datacollection capabilities. Many airliners are already outfitted with Doppler radar and Aircraft Meteorological Data Relay (AMDAR) systems (Drüe et al, 2008), which provide measurements of meteorological variables that include temperature, wind vector, and dew point temperature, and are made available for assimilation into weather forecast models (Petersen, 2016) and for other scientific investigations deemed beneficial to the airlines (Sharman et al, 2014). Advanced sensors for measuring water vapour more precisely have also been tested alongside AMDAR sensors, while the benefits of including on-board infrared sensors (e.g.…”