EGOS-IP Aircraft-based Observations
Implementation Plan for Evolution of the GOS
The fundamental basis for global development of the aircraft-based observing sytem and the AMDAR system is the IMPLEMENTATION PLAN FOR THE
EVOLUTION OF GLOBAL OBSERVING SYSTEMS (EGOS-IP) and, in particular, the actions on Aircraft meteorological stations under Recommendations for the evolution of Surface-Based Sub-system of GOS, Section 220.127.116.11:
18.104.22.168. Aircraft meteorological stations
In the northern hemisphere, meteorological data derived from aircraft stations, especially the
automatic data produced by the AMDAR system, are an excellent complement to the data
derived from the radiosonde network. This system produces vertical profile data in the vicinity of
airports and single-level data when aircraft are flying at cruise levels. It has been shown through
NWP impact studies that their impact on numerical forecasts has a magnitude similar to the
impact of the radiosonde network. In the southern hemisphere and in the tropics the aircraft data
coverage is very poor although there is some potential for developing it, preferably in a way that
is complementary to existing AMDAR and radiosonde networks.
Extending aircraft observations data coverage is important and can be achieved through the
extension of the programme to new airlines and aircraft operating in data-sparse areas. The
programme coverage can also be improved greatly through an optimization process. This can be
achieved through two general activities. Firstly, existing programmes can be extended so that
internationally-operating aircraft are activated for reporting outside the national areas or regions
that tend to be restricted by national programme constraints. Secondly, one can enhance the
capabilities of programmes to control data output through the wider development and
implementation of automated data optimization systems. Such systems, whilst allowing the
efficient growth of the programme outside and across international boundaries with appropriate
agreements in place, will also offer the potential to utilize the AMDAR system as an adaptive
observing network (capability to change the reporting regime to serve the changing purposes of
Action: Improve AMDAR coverage over areas that currently have poor coverage,
especially within Regions I and III, focussing on the provision of data at airports in the
tropics and southern hemisphere where vertical profiles are most needed to complement
current radiosonde data coverage and its likely evolution.
Who: NMSs, NMHSs in collaboration with commercial and other airlines, RAs. AMDAR
Programme Management to lead the action.
Performance indicators: Number of airports where AMDAR measurements are taken.
Amount of vertical profiles and AMDAR data in general, measured by the usual indicators
of current AMDAR programmes.
Action: Extend the AMDAR programme so as to equip and activate more internationally operating fleets and aircraft (i.e. fleets and aircraft flying to and between international
airports outside the country of origin) and extend the use of data optimization systems in
support of improved upper-air observations coverage and efficiency, and also the
adaptive functionality of the system.
Who: NMSs, NMHSs in collaboration with commercial and other airlines, RAs, CBS and
AMDAR Programme Management. AMDAR Programme Management to lead the action.
Performance indicators: The number of airports where AMDAR measurements are
taken and number of vertical profiles per day at each airport. The number of international
airlines and aircraft equipped to provide AMDAR observations. The adaptability of the
Action: Given the nature of the aircraft observing system as an increasingly critical and
basic component of the Global Observing System, seek to establish agreements with
airlines and the aviation industry to ensure that the system, infrastructure, data and communications protocols are supported and standardized within relevant aviation
industry frameworks so as to ensure continuity and reliability of the system.
Who: NMSs, NMHSs in collaboration with national and other airlines and aviation
industry, RAs, CBS and AMDAR Programme Management. AMDAR Programme
Management to lead the action.
Performance indicators: Agreements made with aviation industry partners and
Data produced by humidity sensors are now used operationally from an increasing number of
aircraft both in the USA and Europe, and it is critical and strategic to continue this development
in order to converge to systems which measure humidity as well as air pressure (pressure
altitude), temperature and wind as do radiosondes. Such an extension will provide an increased
opportunity to restructure the upper-air observing systems for efficiency and improvement in
Action: Continue the development and operational implementation of humidity sensors
as an integrated component of the AMDAR system to ensure that humidity data is,
processed and transmitted in the same way as wind and temperature.
Who: NMSs, NMHSs in collaboration with commercial and other airlines and TCs (CBS,
CIMO) and AMDAR Programme Management. AMDAR Programme Management to lead
Performance indicator: A number of aircraft providing humidity data in real-time.
The lower cost of aircraft observations in comparison to the radiosonde information as well as
the reduced reliance on ground-based systems and infrastructure make it an ideal candidate
system for rapid and reliable expansion of upper-air observations for developing countries in
support of local, regional and global data users. Such an expansion should be undertaken in
parallel with the necessary development action to facilitate the provision and utilization of data.
Observations of turbulence and icing are also made on some aircraft and it is desirable to
expand this capability of the AMDAR system with these parameters in support of aviation
operations and safety as well as other meteorological applications.
Action: Enhance and extend the capability to report observations of atmospheric
turbulence and icing variables as an integrated component of the AMDAR system and in
line with the requirements of the relevant programme areas and data users.
Who: NMSs, NMHSs in collaboration with airlines and TC (CBS, CIMO) and AMDAR
Programme Management l, RAs. AMDAR Programme Management to lead the action.
Performance indicator: A number of aircraft providing atmospheric turbulence and icing
data in real-time.
Another source of important potential progress is the research and development actions
associated with AMDAR systems for small aircraft, usually referred to as General Aviation (GA)
aircraft. These aircraft tend to fly and generate level data in the middle troposphere whilst
operating over shorter regional flight legs. This type of observation would be very useful for
regional and local purposes and could also contribute to global data coverage. Priority should be
placed on equipping aircraft operating on, to and out of isolated islands and remote sites where
radiosonde observations are not available, e.g. deserts, islands and the Arctic. The impact of
existing data sets (derived from deployment of the commercial communications and sensor
system) on high resolution NWP models has been evaluated and compared to other observing
systems such as profilers and radars. The results are encouraging: see for example Moninger
et al. (2010) and Benjamin et al. (2010). In spite of several technical snags, AMDAR systems for
GA aircraft do have potential for contributing to the improvement of data coverage of vertical
profiles of AMDAR measurements (wind, temperature, humidity, turbulence and icing) in the
lower troposphere and this development should be pursued whilst taking into account the
potential associated with new and developing technologies such as ADS-B and Mode S.
Action: Develop and implement operational AMDAR systems which are adapted to small
aircrafts operating at the regional scale and flying at low altitude in the troposphere.
Who: Airlines operating small aircraft, NMSs, NMHSs in collaboration with RAs, CBS and
AMDAR Programme Management. AMDAR Programme Management to lead the action.
Performance indicator: Number of small aircrafts providing AMDAR observations
operationally in real-time.
Atmospheric composition measurements for several species, aerosols and volcanic ash are
measured on some aircraft, but more in research than in operational mode. The actions related
to atmospheric chemistry are documented in section 22.214.171.124.