Marc Schneebeli

Palindrome Remote Sensing

A measurement procedure to determine transmitted differential phase between horizontally and vertically polarized radiation of a dual-polarization radar is presented. It is applicable to radars that transmit and receive Simultaneously Horizontally and Vertically (SHV) polarized waves. The method relies only on power measurements and leverages capab...

Calibration measurements with a polarimetric X-band radar and a prototype radar target simulator.

MeteoSwiss operates a polarimetric Doppler X-band weather radar in the Swiss plateau. Its main purpose is to assess the influence of rain on the detection performance of aviation radars. The focus of our application is on low to medium rain rates. Rain rate measurements need to be performed with the highest possible precision and therefore the rada...

MeteoSwiss operates a polarimetric Doppler X-band weather radar in the Swiss plateau. Its main purpose is to assess the influence of rain on the detection performance of aviation radars. The focus of our application is on low to medium rain rates. Rain rate measurements need to be performed with the highest possible precision and therefore the rada...

On MeteoSwiss’ C-band network a nowcasting algorithm that identifies and ranks thunderstorm cells and propagates them in time is being implemented since several years. Data on identified thunderstrom cells is now being taken and transmitted to a mobile X-band polarimetric radar, which then points towards the center of the cell and follows it by con...

The first hydrometeor classification technique based on two-dimensional video disdrometer (2DVD) data is presented. The method provides an estimate of the dominant hydrometeor type falling over time intervals of 60 s during precipitation, using the statistical behavior of a set of particle descriptors as input, calculated for each particle image. T...

This paper presents a hydrometeor classification technique based on two-dimensional video disdrometer (2DVD) data. The method provides an estimate of the dominant hydrometeor type falling over time intervals of 60 s during precipitation, using as input thestatistical behavior of a set of particle descriptors, calculated for each particle image. The...

Orographic lifting of air masses and other topographically modified flows induce cloud and precipitation formation at larger scales and preferential deposition of precipitation at smaller scales. In this study, we examine orographic effects on small-scale snowfall patterns in Alpine terrain. A polarimetric X-band radar was deployed in the area of D...

A new algorithm for the accurate estimation of the specific differential phase shift on propagation (K-dp) from noisy total differential phase shift (Psi(dp)) measurements is presented for data acquired with a polarimetric weather radar. The new approach, which is based on the compilation of ensembles of Kalman filter estimates, does not rely on ad...

The specific differential phase shift on propagation Kdp is widely employed in the study of precipitation, although little is known about the effective accuracy of its estimates. The aim of this letter is to analyze the quality of Kdp estimates, using realistic simulated fields of drop size distributions. Two classical and one recently proposed est...

In mountainous regions, snow accumulation on the ground is crucial for mountain hydrology and water resources. The present study investigates the link between the spatial variability in snowfall and in snow accumulation in the Swiss Alps. A mobile polarimetric X-band radar deployed in the area of Davos (Switzerland) collected valuable and continuou...

An X-band polarimetric radar was deployed in the eastern Swiss Alps at an altitude of 2133 m. Radar measurements were complemented with several weather stations deployed in an altitude range from 1500 to 3100 m as well as with a fixed GPS ground station that was used to infer integrated water vapor estimates. Around 8000 vertical profiles of polari...

An X-band polarimetric radar was deployed in the eastern Swiss Alps at an altitude of 2133 m. Radar measurements were complemented with several weather stations deployed in an altitude range from 1500 to 3100 m as well as with a fixed GPS ground station that was used to infer integrated water vapor estimates. Around 8000 vertical profiles of polari...

A polarimetric X-band radar has been deployed during one month (April 2011) for a field campaign in Fortaleza, Brazil, together with three additional laser disdrometers. The disdrometers are capable of measuring the raindrop size distributions (DSDs), hence making it possible to forward-model theoretical polarimetric X-band radar observables at the...

The different quantities measured by dual-polarization radar systems are closely linked to each other. An extended Kalman filter framework is proposed in order to make use of constraints on individual radar observables that are induced by these relations. This new approach simultaneously estimates the specific differential phase on propagation Kdp,...

During summer and autumn 2007, a 11 GHz microwave radiometer was deployed in an experimental tree plantation in Sardinilla, Panama. With this instrument, the opacity of the tree canopy was derived from incoming brightness temperatures received on the ground. A collocated eddy-covariance flux tower measured water vapor fluxes and meteorological vari...

Accurate positioning of data collected by a weather radar is of primary importance for their appropriate georeferencing, which in turn makes it possible to combine those with additional sources of information (topography, land cover maps, meteorological simulations from numerical weather models to list a few). This issue is especially acute for mob...

A polarimetric X-band radar has been deployed during one month (April 2011) for a field campaign in Fortaleza, Brazil, together with additional sensors like a Ka-band vertically pointing frequency modulated continuous wave (FMCW) radar and three laser disdrometers. The disdrometers as well as the FMCW radar are capable of measuring the rain drop si...

The project CHUVA (Cloud processes of the main precipitation systems in Brazil: A contribution to cloud resolving modeling and to the GPM) is been carrying and its main goal is understand the physical processes involved on the precipitating systems which occur over Brazil. The project plans the setting up of a series of instruments in different par...

A time series of the hemispheric distribution of integrated water vapor (IWV) measured with the All-Sky Multi Wavelength Radiometer is analyzed by means of empirical orthogonal functions (EOFs). The data were acquired in February 2007 at the Zimmerwald Observatory in Switzerland. It is shown that the analysis of temporally demeaned time series yiel...

Accurate positioning of data collected by a weather radar is of primary importance for their appropriate georeferencing, which in turn makes it possible to combine those with additional sources of information (topography, land cover maps, meteorological simulations from numerical weather models to list a few). This issue is especially acute for mob...

During summer and autumn 2007, a 11 GHz microwave radiometer was deployed in an experimental tree plantation in Sardinilla, Panama. The opacity of the tree canopy was derived from incoming brightness temperatures received on the ground. A collocated eddy-covariance flux tower measured water vapor fluxes and meteorological variables above the canopy...

Inversion of tropospheric profiles from ground-based microwavemeasurements requires a simple and accurate model for calculating the brightness temperatures as received by the radiometer. In the first part, an analytic solution of the radiative transfer equation is derived for an exponentially decaying absorption coefficient and a linear temperature...

Calibration of microwave radiometers is a critical task and remains a key issue for the accuracy of brightness-temperature measurements. The tipping-curve calibration method is a well-established technique for ground-based microwave radiometers measuring at frequencies where the opacity of the atmosphere is low. This method relies on the known rela...

An uncooled commercial infrared camera is used to retrieve horizontal winds at cloud-base height. The camera is equipped with a microbolometer array of 320 times 240 pixels covering a field of view of 32deg times 24deg. It operates in the atmospheric window from 7.5 to 14 mum . In this wavelength range, the camera has day and night measurement capa...

During summer and autumn 2007, we deployed a 11 GHz microwave radiometer in an experimental tree plantation in Sardinilla, Panama, in the vicinity of the Panama Canal. With this instrument, we determined the opacity of the tree canopy. A collocated eddy-covariance flux tower measured water vapor and carbon dioxide fluxes as well as other meteorolog...

ASMUWARA, the All-Sky MUlti WAvelength RAdiometer, is a new ground-based and automatically operating radiometer system designed for tropospheric monitoring. ASMUWARA has ten channels in the microwave and infrared range and is able to observe the sky in all directions with an angular resolution of 9°. No radome is used to allow an optimum view quali...

Satellite and ground-based retrievals of a number of (low) cloud characteristics are compared in this paper in order to assess the performance of the techniques and identify potential synergies. Centred on the COST720 International Comparison Campaign for Temperature, hUmidity and Cloud profiling (TUC), four cases with different meteorological situ...

The retrieval of tropospheric water and temperature with the ground-based and automatically operating radiometer system ASMUWARA (All-Sky MUlti WAvelength RAdiometer) is described. This instrument operates simultaneously at microwave and IR channels. Integrated water vapour (IWV) and integrated liquid water (ILW) are retrieved with a newly develope...

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