Jun 272017

The Geoscience & Remote Sensing (GRS) Department organised a poster session held on May 12th at the CiTG building. The aims of the poster day were to stimulate interaction and collaboration among the GRS staff and students and to promote our department to the wider CiTG.
The session was very lively and hosted over 30 posters, from graduate students, teaching and supporting staff, which spanned a wide range of topics. This very successful session sparked the idea of extending it next year by including also other Departments within the TU Delft.


May 262017

Narrow-band Clutter Mitigation in Spectral Polarimetric Weather Radar

Abstract: In this paper, a new clutter suppression method named the moving double spectral linear depolarization ratio (MDsLDR) filter is put forward to mitigate narrow-band clutter in weather radars. The narrow-band clutter observed in the Doppler domain includes: 1) stationary clutter such as ground clutter and 2) non-stationary clutter such as artifacts caused by the radar system itself or external sources. These artifacts are difficult to remove because they are not confined to specific azimuth and range bins. Based on the difference of the spectral-polarization feature and the spectral continuity of precipitation and clutter, MDsLDR filter can remove  ground clutter, artifacts and noise. The performance of the newly proposed filter is assessed by data collected by the Doppler-polarimetric IRCTR Drizzle Radar (IDRA). Three precipitation cases are considered in this paper: moderate/light precipitation, convective precipitation with hook-echo signature and light precipitation with severe artifact contamination. Furthermore, the implementation of the MDsDLR filter requires relatively low computation complexity, so that the MDsLDR filter can be operated in real time.

The full text of the paper from Jiapeng Yin et. al., 2017, can be found here on the IEEE Xplore webpage

May 122017

The EGU general assembly in Vienna, 8-13 April 2017 is a Conference for all scientist interested in geophysical topics. Over 14000 people attended this conference, coming from all over the world. Off-course, the ATMOS group and the GRS department were also represented.

Some Highlights:

The GRS group at the EGU (Not including Stephanie Ruslie and Egli Michailidou):

Gert Mulder giving a presentation on InSAR data assimilation in operational weather models:

Main course of the week:

Scroll trough the GRS tweets, #EGU17 !



May 122017

Following the past symposia in Lille, France in 2007 and in New Orleans in 2010, the 3rd NASA A-Train symposium was held on 19-21 April in Pasadena (California, USA). The NASA A-Train is a unique afternoon constellation including a high value series of instruments (Aqua (2002), Aura (2004), PARASOL (2004), CALIPSO (2006), CloudSat (2006), GCOM-W1 (2012) and OCO-2 (2014)) observing our atmosphere.

Julien Chimot was honoured to give a talk, on Thursday 20 April on our recently achieved developments related to the OMI aerosol layer height neural network development (Chimot et al., 2017) and its applications to urban pollution and biomass burning events.This work has been published in the AMT journal in Mars 2017

Many exchanges allow me to think further about 1) the difficulties, even for LIDAR space-borne sensors, to entirely probe smoke aerosol layers, 2) the possibility to inter-compare OMI and OCO-2 aerosol layer height products in the future.

A lot of talks and posters were focused on their contributions to our aerosol and cloud cycle knowledge, and the forthcoming new generation of satellite instruments such as 3MI on MetOp-SG and the new LIDAR EarthCare. Discussions were also held on the recently launched Chinese mission TANSAT, devoted to CO2 observation, which plans to join the constellation soon. With the American mission OCO-2, there will be 2 satellite missions focusing on the atmospheric carbon cycle!

Finally, it is worth noting the very interesting & inspiring discussion led by Dr. Bruce Wieliecki on the economic value of climate science. Obviously, this is a burning and still very open topic. And it is hard to reach a consensus in our community. But if we want to convince the society with business key words, the (huge!) return of investment of a new climate observing system should then be more quantitatively emphasized to initiate concrete actions.

Great thanks to all the organizers of this symposium (in particular to Liz Juvera) and to all the instrument PIs of the A-Train constellation!


2 weeks later. A poster was displayed by Dr. Pieternel Levelt at EGU 2017. See more details at https://julien-chimot-research.blog/2017/04/30/omi-aerosol-layer-height-neural-network-algorithm-at-egu-2017/

More information?

  • 3rd NASA A-Train symposium 2017 here
  • Talk at the 3rd NASA A-Train symposium: Chimot J., Veefkind P., Vlemmix T., de Haan J., Levelt P., Aerosol layer height retrieval from OMI+MODIS – A neural network approach, 3rd NASA A-Train symposium, Pasadena, California, USA, 2017.04.20 (Talk) here
  • Chimot et al., 2017: Chimot, J., Veefkind, J. P., Vlemmix, T., de Haan, J. F., Amiridis, V., Proestakis, E., Marinou, E., and Levelt, P. F.: An exploratory study on the aerosol height retrieval from OMI measurements of the 477  nm O2 − O2 spectral band using a neural network approach, Atmos. Meas. Tech., 10, 783-809, doi:10.5194/amt-10-783-2017, 2017 here
  • Follow https://julien-chimot-research.blog & @JChimotResearch

The entrance of the Pasadena convention centre, with the banner of the symposium.

Pasadena (California, USA) city-hall

Badge at the 3rd NASA A-Train symposium

Front slide of Julien Chimot talk at the 3rd NASA A-Train symposium, Pasadena (California, USA), 2017.04.20.

Mar 272017

The 11th European Conference on Antennas and Propagation, held in Paris, France, on 19-24 March 2017. Jiapeng Yin, the Ph.D. student in the Atmospheric Remote Sensing Group of the GRS department, made a presentation titled “Spectral Polarimetric Features Analysis of Wind Turbine Clutter in Weather Radar”. This paper was selected to be a finalist for a best paper award, and the finalist papers were requested to present their work in a work in a special poster session dedicated to the Awards. This session took place on Thursday afternoon, March 23, 2017, and gave a possibility for many additional discussions and contacts. Unfortunately, we did not receive the Award.

The increasing size and quantity of wind turbines worldwide provide an environmental-friendly solution to fulfill the growing demand for energy. However, this also brings in a new dynamic clutter named wind turbine clutter (WTC) for weather radars, and it has gradually become a concern because WTC deteriorates the radar performance severely. In this paper, Jiapeng mainly introduced the advanced waveform measurements of WTC using the TUD PARSAX radar. Furthermore, the micro-Doppler signature and the spectral-polarimetric properties of WTC were studied. Finally, a WTC mitigation method was put forward.

Additionally, colleagues from the Microwave Sensing, Signals and Systems Group of EWI, Alexander Yarovoy, Oleg Krasnov, Stefano Medagli, and Sharef Neemat also presented at this meeting.

Mar 212017

Retrieving fall streaks within cloud systems using Doppler Radar


Abstract: Interaction of the ice crystals with super-cooled liquid droplets in mixed-phase clouds leads to an enhanced growth of the ice particles. However, such processes are still not clearly understood although they are important processes for precipitation formation in mid-latitudes. To better understand how ice particles grow within such clouds, changes of microphysical parameters of a particle population falling through the cloud have to be analyzed. The Transportable Atmospheric Radar (TARA) can retrieve the full 3-D Doppler velocity vector based on a unique three-beam configuration. Using the derived wind information, a new fall streak retrieval technique is proposed so that microphysical changes along those streaks can be studied. The method is based on Doppler measurements only. The shown examples measured during the ACCEPT campaign (Analysis of the Composition of Clouds with Extended Polarization Techniques) demonstrate that the retrieval is able to capture the fall streaks within different cloud systems. These fall streaks can be used to study changes in a single particle population from its generation (at cloud top) till its disintegration. In this study fall streaks are analyzed using radar moments or Doppler spectra. Synergetic measurements with other instruments during ACCEPT allow the detection of liquid layers within the clouds. The estimated microphysical information is used here to get a better understanding of the influence of super-cooled liquid layers on ice crystal growth. This technique offers a new perspective for cloud microphysical studies.

The full text of the paper from L. Pfitzenamier et. al., 2017, can be found in the here on the J-Tech web page


Jan 242017

This year, 2017, on March 27th – 31st an international workshop on “Turbulence in Stably Stratified planetary boundary layers” will be held at the Delft University of Technology, Netherlands.

This workshop is organized by ATMOS group members; Bas van de Wiel, Sukanta Basu, Peter Baas, Steven van der Linden and Bert Holtslag from Wageningen University and Research.

Purpose of this decennial meeting is to assess the ‘State-of-the-art’ in SBL research and to see in what directions the research field is moving. Moreover, we aim to probe into the contemporary scientific problems and challenges and to find the critical issues that will require extra attention in the near-future.

The meeting is the third in line after successful predecessors of Lovanger (Sweden; 1997) and Sedona (U.S.; 2007). For an overview on those meetings, see the references below.

The setup of the meeting is unlike a ‘regular conference’, in a sense that the latest results from each presenter’s own group will not be the main focus. Rather, for each scientific topic (two) keynote speakers have been invited. Those speakers will give an overview on the topic (for example a brief historical outline) and –identify the challenging questions related to this topic. Next, the questions are collected and discussed in subgroups of participants who will present their findings in one summary slide. Lastly, the topic is wrapped up during a panel discussion.

In addition to the keynote speakers and other participants, PhD students are also invited. They are encouraged to present a poster with challenging questions related to their research. The best poster will receive a prize and its topic will be discussed in subgroups as well.

List of keynote speakers:

Acevedo, Anderson, Angevine, Ansorge, Beyrich, Edwards, Fedorovich, Galperin, Grachev, Holtslag, Jonker, McNider, Mironov, Sorbjan, Steeneveld, Sullivan, Sun, Zilitinkevich

Keywords discussion topics (inter alia): 

Coherent structures and global intermittency (numerical & observational aspects); non-traditional SBLs: MO vs. non-MO similarity; transitional SBLs; radiative SBLs; polar/long-lived SBL; surface heterogeneity & mesoscale effects; urban SBL; recent observational & theoretical developments; total turbulent Energy concepts; atmosphere-surface interactions, gravity waves & turbulence… 

For more information and regristration please visit: www.sbldelft.nl

Photo: Riccardo Riva
Photo: Riccardo Riva

Jan 192017

17 February 2017 | 12:45 – 18:00
location: Theaterzaal (Sport & Culture)


Please register by sending an email to Secr-grs-citg@tudelft.nl.

The Geoscience & Remote Sensing (GRS) department of TU Delft, the TU Delft Climate institute and he Royal Netherlands Meteorological institute KNMI are pleased to invite you to the seminar Urban Air Quality, to be held at the TU Delft Theaterzaal (Sports & Culture) on Friday afternoon 17th February 2017.

Human activities, including industry, traffic, energy generation and food production, have an adverse impact on air quality. This is especially the case in urban areas, where more than half of the world populations lives. Ground based and satellite observations show that policies to reduce the emissions of pollutants are successful in improving air quality. However, is enough done to protect the health of the people in the cities and what can cities in developing countries learn from these successes?

This symposium will bring together experts in the field of  health effects, policy, emission monitoring, ground based observations and satellite remote sensing. It targets a broad audience from students in diverse topics, public, industries, policy makers and researchers. In addition to presentations, there will be possibilities for interactive discussions with the speakers.

See the program below

Dec 092016

The increasing size and quantity of wind turbines worldwide provide an environmental-friendly solution to fulfill the growing demand for energy. However, this also brings in a new dynamic clutter named wind turbine clutter (WTC) for weather radars, and it has gradually become a concern because WTC deteriorates the radar performance severely. During December 6-7, to bring together the increasing number of experts and researchers in the field of electromagnetic waves within the context of wind energy plants and to offer a platform to discuss arising and existing problems, the focus days EMWT’16 provide a fitting platform. In contrast to other conferences EMWT’16 will cover the whole field of electromagnetic waves and wind energy in one specialist meeting in Fraunhofer Institute for High Frequency Physics and Radar Techniques .

Jiapeng Yin, the Ph.D. student in the Atmospheric Remote Sensing Group of the GRS department, made a presentation named “Signatures Study of Wind Turbine Clutter in Polarimetric Doppler Weather Radar” . He mainly introduced the micro-Doppler signature and the spectral-polarimetric properties of WTC based on the measurements of the PARSAX radar in TU Delft campus. This work relies on a recently-accepted conference processing of European Conference on Antennas and Propagation.

Additionally, colleagues from the Microwave Sensing, Signals and Systems Group of EWI, Oleg Krasnov, Faruk Uysal and Stefano Medagli also presented in this meeting. More information can be found on the following websites:


IMG_0674             IMG_0635               IMG_0617

Dec 082016

A novel drone-based radar calibration experiment is carried out by Jiapeng Yin, Jinliang Li and Fred van der Zwan on Novermber 1st and 3rd. The research aims to develop and implement the new technology in calibration for the next generation of weather radars. This is urgent and timely research as the current weather radars are not the optimum information sources for water management in urban areas – so prone to the increased occurrence of extreme rainfall. This research will use a micro-drone hexacopter to  carry the metal sphere and fly over two radars (S-band TARA and X-band IDRA) to complete the process in Cabauw.

DSC04278   IMG_0393  IMG_0291