Harry Otten Prize for Innovation in Meteorology: Finalists' Session


A substantial part of the national gross product in many countries is weather dependent. National weather services and the private sector have been innovative for more than a century to make better use of our meteorological knowledge. However, large gains are still to be made and this prize encourages individuals and groups to come with ideas how meteorology in a practical way can further move society forward. Meteorology can make society safer, can deliver costs savings and can bring more welfare to large groups of people. More information about the Prize and the Foundation can be found at

Applications for the 2021 Harry Otten Prize were possible until March. The jury selects three finalists who will give presentations at the EMS Annual Meeting explaining their ideas. The prize winner will be announced in the Awards Session on Tuesday 7 September 2021.

Convener: Pamela Emch | Co-conveners: Andrea Oestreich, Gert-Jan Steeneveld
| Mon, 06 Sep, 16:00–17:30 (CEST)

Session assets

Session materials Session summary

Presentations: Mon, 6 Sep

Moritz Mauz

A chilled-mirror hygrometer (CMH) prototype for in-situ UAS (unmanned aircraft system) measurements has been developed and compared against industrial state-of-the-art alternative light-weight humidity sensors. It is shown that the newly developed sensor resolves dew-point measurements up to 10 Hz at a sampling frequency of 50 Hz, and can therefore resolve turbulent dew-point fluctuations, measured by UAS. The CMH sensor is relatively low cost, and easy to maintain. The latest version of the sensor combines an in-house made housing and circuit board and is tuned to fit in the MASC-3 (multi-purpose airborne sensor carrier) research UAS of the University of Tübingen. However, the sensor can be modified to compliment EC (eddy-covariance) stations that monitor turbulent surface fluxes (e.g. turbulent vertical humidity or momentum fluxes) where the CMH sensor would substitute expensive equipment.
The proposal substantiates further how the sensor can be used for several meteorological applications, e.g. an installation of a low-cost EC-stations network, studying the CBL (convective boundary layer) or buoyancy-driven flows in general, since the sensor is able to resolve turbulent density fluctuations once combined with pressure and temperature readings. It is shown that the CMH sensor supports a comprehensive evaluation of turbulence in the atmosphere, including the hard to measure structure parameter for humidity C2q that quantifies turbulent eddies and structures in the lower atmosphere.
Field campaigns and validation measurements against i.a. scintillometers and meteorological mast measurements have been conducted and new ones are planned for the future, together with the German Meteorological Service (DWD). Constant development of the CMH continuously improves the sensor and motivates a secondary goal; the possibility to offer a commercially available product to the meteorological community and the humidity sensor industry in the future. The market situation and a realistic reception of such a sensor have previously been assessed and has evolved in two business plans.

How to cite: Mauz, M.: A high-frequency chilled-mirror hygrometer for turbulent stationary and airborne dew point measurements, EMS Annual Meeting 2021, online, 6–10 Sep 2021, EMS2021-508,, 2021.

Joshua Soderholm

From the early stages of hailstone growth to the ground-impact finale, a trajectory is taken by each hailstone through the parent hailstorm. Larger hailstones form as their trajectory takes them into regions of the storm that are more favorable for growth, while others may miss out entirely. Simulation-based studies have shown that interactions between the hailstone fall speed, aerodynamics, storm winds (which continue to change along the trajectory and with new growth) can take hailstones on a myriad of different trajectories. Despite improvements in radar technology over the last 20 years, operational hail analysis techniques have changed little, and do not consider trajectories, leaving a high degree of uncertainty when estimating ground impact.

Case studies have demonstrated that trajectory information provides significant improvements to hail impact mapping and nowcasting services, but the lack of robust
observational datasets to leverage new radar technology and verify trajectories prevents the transition of this new science into operations. The follow proposal presents an innovative approach to measuring trajectories within a hailstorm using hailstone-shaped probes called “HailSondes”. Recent advances in low-energy telemetry, battery technology and electronics miniaturization are combined to make this new sensor possible, which, until recently, was the realm of fantasy for meteorologists (e.g., the 1996 Hollywood classic “Twister” imagined a similar sensors for observing tornadoes). The design challenges, simulations, prototype development and deployment of HailSondes are discussed.

HailSonde measurements will provide critical validation for the practical application radarderived trajectories for hailstorm analysis and nowcasting, supporting the transition to future hail services and benefiting a wide range of sectors from aviation, risk management, transport and public safety. This transition from science fiction into real science signifies extraordinary potential for further remote micro-sensor applications in the future. 

How to cite: Soderholm, J.: Observing the impossible – in situ observations of hail trajectories using the HailSonde, EMS Annual Meeting 2021, online, 6–10 Sep 2021, EMS2021-509,, 2021.

Kirien Whan and Kate Saunders

Extreme wind gusts have severe socio-economic impacts, so any source of extra information on this variable is invaluable for mitigating associated damages and
protecting vulnerable communities. Unfortunately, networks of ocial measurement stations are limited in their ability to observe wind gusts. Official stations
are separated by vast distances, so extreme wind gusts often go unobserved due to the highly localised nature of these events. A wealth of additional observa-
tions is available from personal weather stations (PWSs) and could be used in combination with official observations to observe extreme gust events. However,
concerns about underlying data quality have to date prevented the usage of gust data from PWSs.

Research for other meteorological variables has demonstrated that with appropriate quality control PWSs can contribute high-quality observations that complement ocial measurements. It is well known that PWSs can provide useful and reliable temperature and precipitation observations. For crowd-sourced wind variables, the situation is more dicult. Crowd-sourced wind observations have di erent sources of error that pose signi cant challenges to quality control. For example, instrumentation is non-standard which results in di erent sensor sensitivities, and non-standard station placements introduce severe spatial in-consistencies and result in censoring of low wind speeds. Chen et al. (2021) recently developed a  exible approach to quality control and bias adjustment (QC/BA) that addresses this for wind speeds. They incorporate QC steps for official stations and develop new QC/BA steps to address the novel challenges posed by crowd-sourced data. Chen et al. (2021) showed after QC/BA, the wind speed climatology of a network of PWSs matched well with the climatology of ocial stations, and the wind speed variability between PWSs was similar to that of official  tations. Additionally, subsequent analysis has shown that the quality controlled and bias adjusted data from PWSs is able to detect small scale extreme wind speeds  ssociated with thunderstorms, that were not observed at official stations. No attempt has yet been made to quality control crowd-sourced observations of wind gusts  espite how impractical it is to obtain widespread observations of wind gusts using standard techniques.

In this project we will develop the necessary methods and software for the QC/BA of wind gusts. As part of this, we will develop inter-variable consistency checks between crowd-sourced wind speeds, wind gusts and wind directions. We will also produce an open-source, high-quality wind gust data set from PWSs that can be used to improve forecasts, warnings, and veri cation of extreme gusts.


Chen, J., Saunders, K. & Whan, K. (2021), `Quality control and bias correction of citizen science wind observations', Quarterly Journal of the Royal Meteo-
rological Society (under review) .

How to cite: Whan, K. and Saunders, K.: Second Wind: Extending the official wind gust records with citizen science observations, EMS Annual Meeting 2021, online, 6–10 Sep 2021, EMS2021-510,, 2021.


Additional speakers/contributors without abstracts

  • Olivier Boucher, CNRS / Sorbonne Université, France
  • Dennis Schulze, MeteoIQ, Germany
  • Harry Otten, Netherlands

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