Yann Dufournet

Oct 142012

During IOP 12 several location have been chosen to launch radiosondes at the same time. Our students helped at launching radiosondes at the TARA site. Radiosondes are used to record profiles of the atmospheric state (temperature, pressure, humidity, wind) at high spatial resolution. The dedicated probe that we can see on the right picture is attached to a balloon filled with Helium which bring the probe up to 12-15 km height. At such height, the balloon usually increases so much in volume due to the difference of pressure with the surrounding that it explodes. Data recorded are transfered via radio frequence to the surface where they are processed and displayed near real time. For hymex, data are recorded and kept in both ascent and descent of the probe within the atmosphere.

As shown on the pictures below, such activity was once again successfull due to a great team work spirit among the students 😉


Oct 102012


On Tuesday 9th October, we have been visiting two research aircrafts, from the SAFIRE fleet, which are used in Hymex. Such aircrafts are very usefull to complement the observational network of ground based instruments as they can be directed over the area of interest depending on the weather evolution, increasing the amount of data acquired during an event. These two aircrafts are located at Montpellier airport during the whole campaign: the ATR 42 and the Falcon 20:

ATR42 (Safire)

Falcon 20 (Safire)







Instrumentation on board the aircraft have been tuned for different observation purposes:

lidar onboard the ATR42 aircraft


  • The ATR42 is used to observe the key factors for initiation of convection: the humidity and temperature fields, as well as  the very small particles present in the air (chemistry and microphysical properties of aerosol particle). In-situ probes and lidar system are mounted onboard this aircraft.



Multi beam 95 GHz radar RASTA


  • On the other hand, the falcon 20 is used to document the processes occuring within the convective event. It is also equipped with in-situ probes and a mutli-beam radar capable of measuring hydrometeors size and concentration present in the cloud system.



We would like to thanks again the Safire team to let us visit the aircraft at the airport!

Oct 012012

    The HyMEx Campaign (see presentation of the campaign) officially started in September 6th this year for a special observation period of 2 months. The TARA radar arrived on site in August 28th and started to operate on the 29th in the evening, providing already some nice measurements which shall be processed soon (some posts might follow soon on the ATMOS weblog ).

This TU Delft project also involved students (3 masters and 2 phd) in this adventure. The 3 master students are involved in short projects under a DRI environment initiative. They started a preparatory work at TU Delft (co-supervised by Christine Unal and Igor Stepanov) begining / mid september. Two of them, Kyriaki and Ning are directly invovled with the data processing of the TARA radar. The other student, Bas Crezee is working on a cloud resolving model (ARPS) in order to simulate one heavy previpiation event that occur during this campaign.

visit of the research aircrafts

opearating the TARA radar








Since 1st October, they officially started the fieldwork part of their project. They will be on site for the coming for 2 to 3 weeks and will then return to TU Delft to finalize their project. The main goal of the fieldwork part is to provide students a global understanding of how such an international experiment is operated. This fieldwork is, therefore, combining visit of the different ressources which have been deployed for the measurement campaign, work on their own topic as well as learn how to operate the TARA radar during precipitation events.

forecast section at the Hymex operation center

visit of the NSSL radar (National severe storms laboratory)



Impression of the students, regarding these activities, can be found under the student logbook section of this weblog.

Enjoy the reading!