May 182018

Vertical profiles of aerosol mass concentration derived by unmanned airborne in situ and remote sensing instruments during dust events

D. Mamali et al.


Abstract. In situ measurements using unmanned aerial vehicles (UAVs) and remote sensing observations can independently provide dense vertically resolved measurements of atmospheric aerosols, information which is strongly required in climate models. In both cases, inverting the recorded signals to useful information requires assumptions and constraints, and this can make the comparison of the results difficult. Here we compare, for the first time, vertical profiles of the aerosol mass concentration derived from light detection and ranging (lidar) observations and in situ measurements using an optical particle counter on board a UAV during moderate and weak Saharan dust episodes. Agreement between the two measurement methods was within experimental uncertainty for the coarse mode (i.e. particles having radii  > 0.5 µm), where the properties of dust particles can be assumed with good accuracy. This result proves that the two techniques can be used interchangeably for determining the vertical profiles of aerosol concentrations, bringing them a step closer towards their systematic exploitation in climate models.
The full article can be found here.
Nov 032017

TU Delft is participating in the MUFFIN campaign (Multi-Scale Urban Flood Forecasting: From Local Tailored Systems to a Pan-European Service) aiming to study urban flood forecasting from a multi-scale multi-disciplinary perspective, that is from the point of view of different scientific, technological and social disciplines. TU Delft is represented by the Atmospheric Remote Sensing Group collaborating with fellow-scientific groups in Denmark, Finland and the leading group in Sweden (SMHI) with the aim to develop, implement and test different urban flood forecasting systems in 3 major European cities: Rotterdam (Netherlands), Aalborg (Denmark) and Helsinki (Finland). The key components studied in these experiments are:

1. The role of the rainfall input: both in terms of real-time and in the form of numerical forecasts at different spatial and temporal resolutions.
2. The land-use data and associated information such as imperviousness and soil infiltration capacity and how they impact the hydrological response.
3. The flood forecasting model: either in the form of tailored solutions accounting for local surface/sub-surface flows or from a larger-scale perspective (e.g., integrated basin runoff).

The goals are to specify the requirements in all these 3 key aspects for different end-user categories, to explore the trade-offs between scale, accuracy and end-user value and assess the limits of current state-of-the-art urban flood forecasting systems. A key aspect of the project is active end-user involvement and multi-disciplinary collaboration between different stakeholders.

The main task and responsibility of TU Delft within MUFFIN is to collect high-resolution weather data in Rotterdam to study the spatial organization and dynamics of rainfall over urban areas and perform fundamental research into the science underpinning the measurement and forecasting of heavy localized convective storms.

Significant progress has been achieved in 2017 with the acquiring of many new datasets including:

• The Rotterdam X-band rain radar: 1-min horizontal scans with a range of 30 km and a horizontal resolution of 100m are being transmitted in near real-time to a TUD server (from August onwards).
• The Micro-rain radar (MRR): A MRR has been purchased and installed on the roof of the CiTG building at TUD. It collects vertical profiles of rain rates, reflectivity, liquid water content and particle size distributions at 10 s and 35 m resolution to study the vertical variability of rain from the clouds down to the ground.
• WRF Modelling: the state-of-the art Weather Research and Forecasting software (WRF 3.9) has been set up over Rotterdam and can be used to perform high-resolution numerical weather modelling and forecasting for selected rainfall events. The model has a parent domain of 5 km grid spacing covering the entire BeNeLux region, a second domain of 1 km grid spacing over the Netherlands and a third innermost domain over Rotterdam at 200 m grid spacing and 135 vertical levels. Both single- and double-moment microphysics schemes have been implemented.
• Citizen weather data: Rainfall, temperature, wind and pressure from hundreds of citizen rain gauges in and around Rotterdam are being collected since January 2017.
• Professional 5-min weather data (rainfall, temperature, relative humidity and wind) from 10 TU-Delft operated weather stations in/around the city of Rotterdam to validate the radar rainfall products.

The Rotterdam Radar



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:

Photo: Riccardo Riva
Photo: Riccardo Riva

Sep 232016

Assessment of the rain drop inertia effect for radar-based turbulence intensity retrievals

A new model is proposed on how to account for the inertia of scatterers in radar-based turbulence intensity retrieval techniques. Rain drop inertial parameters are derived from fundamental physical laws, which are gravity, the buoyancy force, and the drag force. The inertial distance is introduced, which is a typical distance at which a particle obtains the same wind velocity as its surroundings throughout its trajectory. For the measurement of turbulence intensity, either the Doppler spectral width or the variance of Doppler mean velocities is used. The relative scales of the inertial distance and the radar resolution volume determine whether the variance of velocities is increased or decreased for the same turbulence intensity. A decrease can be attributed to the effect that inertial particles are less responsive to the variations of wind velocities. An increase can be attributed to inertial particles that have wind velocities corresponding to an average of wind velocities over their backward trajectories, which extend outside the radar resolution volume. Simulations are done for the calculation of measured radar velocity variance, given a 3-D homogeneous isotropic turbulence field, which provides valuable insight in the correct tuning of parameters for the new model.

The full paper from A. Oude Nijhuis et. al. can be found here

Nov 182015

Members of the ATMOSpheric remote sensing groupe contrubuted to the AMS conference, 14-18 September 2015, Norman OK, USA

Ricardo Reinoso Rondinel contributed presenting a poster:

Title: “High resolution estimation of specific differential phase and backscatter differential phase for polarimetric X-band weather radars

  • An advanced method to estimate the specific differential phase (Kdp) and backscatter differential phase (dhv) from rain at X-band frequencies is proposed. The method aims to obtain high spatial resolution of Kdp and dhv estimators while controlling their inherent bias-variance dilemma. In addition, the variance of Kdp was mathematically formulated for quality control.
  • Poster and abstract link here
  • This poster was awarded as the 3rd best student poster presentation.

Albert Oude Nijhuis  presented a poster, too:

Title: “Turbulence intensity retrieval in precipitation via optimal estimation using polarimetric radar

Summary and a pdf version of his paster can be found here

The talks of Lukas Pfitzenmaier

Title: “Correcting radar Doppler spectra for atmospheric dynamics to study microphysics within mixed phase clouds” (here)

and Yunlong Li

Title: “A Novel Radar-Based Visibility Estimator

are also avilable online (here)

Mar 142015

On Wednesday 29th October 2014 was the official kick-off meeting of Waterlab which took place in the Science Center of TU Delft (link1, link2). Almost 300 pupils from primary schools of Delft had a first hint about science and rain measurements.

Currently, four primary schools in Delft area are involved in the project. The teachers and pupils measure local precipitations with handmade raingauges and compile all measurements to a dedicated website called MijnWaterlab. Besides these observations, rainfall intensities are also measured continuously since September 2014 with weather stations located in each of these schools (see picture on the right) in order to have a better idea about the variability of precipitation at the scale of a city. Easy comparisons can be made between each dataset.
On the other hand, in the upcoming weeks, students from secondary schools from Delft will integrate the project and the roof of these lyceums will be equipped with a station for measuring rainfalls. The students there will have to deal with scientific projects in relation with the analysis of these observations.


Since today, another weather station is also located in the Science Center to continue with the densification of the network of stations in Delft. The particularity of this station is that the data are collected automatically via wired internet connection with the use of a RaspberryPi-based system (see picture on the right) that was under development during the last months.
A quasi-similar configuration (using 3G wireless internet connection) will be applied very soon to the stations installed in schools (currently a visit to each school is needed to manually collect the data).

Sep 292014

One day before the conference, there were full day workshops to reinforce our knowledge related to Doppler spectra, rainfall estimation, and open radar data source.

The ERAD 2014 was held in the beautiful mountain city called Garmish-Pathenkirchen. The conference last for 5 days inviting multi-national researchers for productive discussions through oral and poster presentations. Besides scientific talks, the conference organized several events such dinner and excursions so that everyone can have a nice chance to get to see familiar faces and/or know new ones. In particular, for me it was nice to see again friends from the University of Oklahoma such Bob Palmer, Tian Yu, Sebastian Torres, and Brad Isom. Also, very close friends from the EPFL in Switzerland Jacopo, Tim, and Marc. We all shared interesting discussions about radar meteorology of course but also a good and friendly talks along with typical Bavarian food such bretzel and withe sausages and Schweinebraten as shown in the pictures below.

image_1 image_3

If you are interested in Mesoscale and Severe weather studies (poster) (abstract) or liquid layer detection within mixed phase clouds (poster) (abstract), you can find the poster that we presented at ERAD clicking on the links for the extended abstract as well

NEWS !!!

ERAD 2016 will be hold at Antalya in Turkey promising very good weather near the beach.

Tian Yu and Alexander Ryzhkov announced that the next AMS Radar Conference will take place in Oklahoma, USA, where we will be able to see very advanced laboratories facilities for weather radar applications.

Sep 242014

From 8th to 17th September 2014, the 2nd Summer School of the ITaRS community took place in the Institute of Energy and Climate Research (IEK) at the Research Center of Jülich (Germany). Dimitra, Edouard and Lukas participated to the summer school.

We had the opportunity to meet academia and industrial experts of the clouds and precipitation remote sensing community. The lectures were very interesting and led to fruitful discussions between fellows and all the invited partners.

Besides attending the lectures, we also worked on challenging team projects by using measurements from the instruments of the ground-based JOYCE station. Lukas’s team won the right to take part to the upcoming TOPROF workshop in Copenhagen, Denmark (18-20 November 2014).

It was very nice to see again all the fellows. Once we spent a nice evening in beautiful Cologne. The summer school was also about sports: we played once a football match and we were cycling every morning and every evening between our hotel downtown and the research center.

Jun 202014

EuCAP 2014 – The 8th European Conference on Antennas and Propagation, has been held at the World Forum in The Hague, The Netherlands, on 6-11 April 2014. Our colleague Yunlong Li, presented his paper entitled “Radar Observations and Modeling of Fog At 35 GHz“. This is the first time that a 35 GHz cloud radar at the Cabauw Experimental Site for Atmospheric Research in the Netherlands has been used for fog measurements. However, measuring fog with cloud radars is still a challenge in technical issues. Any suggestions and collaborations are welcome if you are interested in fog radar.

Jun 202014

On 18-06-2014 the CESAR-scienceday 2014 took place at KNMI. During this meeting the whole spectrum of scientific research related to the research side in Cabauw (CESAR) was presented.

The ATMOS group contributed with two posters (L. Pfitzenmaier and Y. Li) and two presentations (A. Oude Nijhuis and L. Pfitzenmaier).

During this Meeting also the upcoming measurement campaign ACCEPT (Analysis of the Composition of Clouds with Extended Polarization Techniques). All the other presentations and posters will be available soon at the webpage of the CESAR science day 2014 soon.