Oct 032014

Last installation day. All the instruments are working fine at the moment so that first measurements for inter comparison  are taken till Monday. So the antenna elevation of TARA was changed and but to the zenith. The other radar systems are set to the same elevation. Till the weather forecast looks that there will be a frontal overpass during the weekend the needed clouds will be there. Before the frontal overpass the conditions for cirrus clouds should be given. So it should be possible make some good measurements with the HALO camera system from LMU to. So on Monday we then know how stable the systems are working and how good the data look.


Oct 022014

All the instruments are working fine, at least they collect some data if you plug in the electricity. So the second day was mainly to calibrate the instruments and to install the second Mira 35. Also some maintenance at TARA have been done.


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Like the pictures show, calibrating the microwave radiometer involves handling liquid nitrogen. It is needed to create a low and stable temperature compared to the ambient one. This low temperature are needed to calibrate the sensors of the microwave radiometer. To test if the polarimetric capabilities of the Mira35-STAR mode radar are still correct some tests were made. A transmitter was installed to test if the receiver characteristics are still OK.

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Also the quick-look page was part of the work from yesterday. As soon if all things work the link will appear in the weblog. Helium was also delivered. So now we can also launch some radiosondes. If you want to be in Cabauw during the first launch of the campaign register for the Kick Off on the 7th of October (see the post).


Oct 012014

The containers with the instruments from TROPOS (Leibniz Institute for Tropospheric Research,  Leipzig, Germany) were already waiting for us when we were arriving in the morning at Cabauw. So it was basically jumping out of the car and start to work. The LACROS container (Leipzig Aerosol and Clour Remote Observations System) was placed next to TARA. It is equipped with a cloud radar (Mira35, Metek), a microwave radiometer (RPG), a disdrometer, a ceilometer (JenOptic CHM 15k) and a Doppler lidar (HALO Photonics).  A second container is placed next to the Cabauw tower. It contains a Raman lidar system (Polly).

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After placing the containers the installation of the instruments begin. Screwing lags on instruments, fixing antenna for the radiosonde launches some first instrument tests have been made. So the laser beam of Polly is not hitting some cables at the tower and after changing the  antenna of the radiosonde the noise in the radar was reduced significantly. In the evening also the second cloud radar arrived so that the whole setting can be tested today

Our colleagues from Munich were at the side. After inspection of several locations, and some discussions and phone calls they decided to go to the KNMI headquarter to set up their HALO camera.

Sep 292014

Today the last check at CESAR was done. Now we have

– enough space for all the instruments, that will come tomorrow

– clouds are there as well, it already started to rain

– and also we have now liquid nitrogen to calibrate the microwave radiometer, and the helium for the radiosondes will come in two days.

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From tomorrow on, the installation of the instruments will start. We hope all the material and the people arrive safe in the Netherlands. So let’s start the instruments installation phase of the campaign…

Sep 262014

In less than 10 days, a new measurement campaign (Accept – Analysis of the Composition of mixed-phase Clouds with Extended Polarization Techniques) will take place at the CESAR observation site (Cabuw, The Netherlands). Our group (ATMOSpheric remote sensing group of Department for Geosince and Remote Sensing of TU Delft) is greatly involved in it. On behalf of the campaign team, I would like to invite you all to the Kick-Off of the campaign which will be on Tuesday 7th October at the CESAR observatory in Cabauw, from 11:00 to 15:00.

ACCEPT flyer Kick off

During that day, a short presentation of the campaign objectives as well as a tour of the different instruments will be given. This is a great chance to get information about the extended instrumental setup that will be deployed during the campaign. Together with colleagues from TROPOS (Leibniz Institute for Tropospheric Research – Leipzig, Germany), the LMU (Ludwigs Maximillians Universities – Munich, Germany), Metek (Meteorologische Messtechnik GmbH – Elmshorn, Germany) and KNMI (Royal Dutch Weather Service – The Netherlands), we are glad to be able to operate a set of state-of-the-art instruments for atmospheric measurements running at Cabauw.

In the following eight weeks we are going to focus on mixed-phase clouds  measurements. Mixed-phase clouds are frequently observed in the atmospheric temperature range between -40 and 0 °C where cloud water droplets and ice crystals can coexist. The composition of these mixed-phase clouds, i. e., the partitioning of liquid water and ice, plays a crucial role in the formation of precipitation and in the cloud radiative effect. The precipitation of ice crystals through layers of super-cooled liquid water affects ice crystal growth and shape. An instrumental setup composed of Raman lidars, cloud radars, precipitation radars, and microwave radiometers will be used in synergy in order to address this topic. To measure the dynamics we have a wind profiler and a Doppler lidar, the disdrometer measures the rain drop size distribution and radiosondes give information about  the atmospheric conditions. We also have a HALO camera to characterise ice crystal shapes of cirrus clouds. The different frequencies of the sensors allow us to study many different cloud process and retrieve in the end the cloud microphysics.

So we will make a tour through all the instruments, launch the first radiosonde and will have lots of time to talk and explain more details while having some food and drinks.

If you are interested please let us know before end of next week (Friday October 3rd) by sending an e-mail to l.pfitzenmaier@tudelft.nl or y.dufournet@tudelft.nl , that we can prepare all the food and drinks

So I hope to see many of you that day

Jul 032014

Since a few weeks we learn how to operate the CESAR Water Vapour, Aerosol and Cloud Lidar – CAELI. Since CAELI is a non fully automatic system the operation procedure takes time to learn. To be able to make nice measurements during ACCEPT we are going to test some instrumental setting to be able to get a proper lidar signal during cloud conditions. This has to be done because at the moment CAELI is mainly used for aerosol studies. Quicklooks of CAELI measurements can be found on found here

Cabauw_sunset Cabauw_CAELI_Arnoud_Dimitra Cabauw_Caeli_2Caeli_laserbeam

Jun 202014

On 18th June 2014 the CESAR science day 2014 took place at KNMI, de Bilt. During this work shop the ACCEPT campaign was introduced by L. Pfitzenmaier. The presentation pointed out the motivation for this campaign, having more mixed-phase cloud observations and comparing different remote sensing techniques. It also gave an overview about the instruments taking part in ACCEPT and the topics that will be tackled with this data. The data base will be open, so if you are interested in the data you are welcome to use them. If you want too have more information or contribute in the campaign feel free to contact us (mail adresses could be found in the presentation).