Publications de Valentin Simeonov

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The water vapor profile derived from Raman lidar measurements is obtained by taking the ratio of water vapor and nitrogen Raman-shifted signals. The proportionality factor that converts the signal ratio to water vapor/air mixing ratio is referred to as lid ...

The flux of water vapor due to advection is measured using high-resolution Raman lidar that was orientated horizontally across a land-lake transition. At the same time, a full surface energy balance is performed to assess the impact of scalar advection on ...

This paper concerns an evaluation of ozone (O-3) and planetary boundary layer (PBL) dynamics over the complex topography of the Grenoble region through a combination of measurements and mesoscale model (METPHOMOD) predictions for three days, during July 1999. The measurements of O-3 and PBL structure were obtained with a Differential Absorption Lidar ( DIAL) system, situated 20 km south of Grenoble at Vif (310m ASL). The combined lidar observations and model calculations are in good agreement with atmospher

The Grenoble metropolitan area located in the French Alps with more than 400 thousand inhabitants suffers from periods of high ozone (O3) concentrations in summertime. Grenoble is moreover located in the Y shaped convergence of three deep valleys with surrounding mountains up to 3 000 m above sea level (asl) leading to a very complex wind pattern. During summer 1999, a major field campaign GRENOble PHOTochemistry (GRENOPHOT) involving standard ground based stations, LIDAR, aircraft, DOAS, microwave windprof

A new lidar instrument was developed to measure tropospheric ozone and water vapor at low altitude. The lidar uses Raman scattering of an UV beam from atm. nitrogen, oxygen, and water vapor to retrieve ozone and water-vapor vertical profiles. By numerical simulation the authors study the sensitivity of the method to both atm. and device perturbations. The aerosol optical effect in the planetary boundary layer, ozone interference in water-vapor retrieval, statistical error, optical cross talk between Raman-s

[1] During the last 5 years, information on the regional tropospheric ozone levels over the eastern Mediterranean has become available but was confined to measurements at ground level. Here available information is expanded with measurements at two more rural ground level sites spanning 8 latitude, ozonesonde ascents, lidar observations, ship cruises, and aircraft flights. During wintertime the ozone monthly values are 1020 ppbv higher than values at other European sites, while during summertime the values

The Grenoble metropolitan area located in the French Alps with more than 400 thousand inhabitants suffers from periods of high ozone (O3) concns. in summertime. Grenoble is moreover located in the Y shaped convergence of three deep valleys with surrounding mountains up to 3,000 m above sea level (asl) leading to a very complex wind pattern. During summer 1999, a major field campaign GRENOble PHOTochem. (GRENOPHOT) involving std. ground based stations, LIDAR, aircraft, DOAS, microwave windprofilers was carri

The Jungfraujoch Research Station (46.55 degrees N, 7.98 degrees E, 3580 m above sea level) for decades has contributed in a significant manner to the systematic observation of the Earth's atmosphere both with in situ measurements and with trace gas column detection. We report on the development of a lidar system that improves the measurement potential of highly resolved atmospheric parameters in both time and space, with the goal of achieving long-term monitoring of atmospheric aerosol optical properties a

Retinoblastoma is the most common pediatric eye cancer. It is currently treated with a limited number of drugs, adapted from other pediatric cancer treatments. Drug toxicity and relapse of the disease warrant new therapeutic strategies for these young pati ...

l Here we present unique evidence of a k(-1) scaling behaviour in the atmospheric boundary layer and its connection to large scale coherent structures within the boundary layer. Wind lidar measurements were conducted above a lake under cold atmospheric con ...

Single-pass Raman cells pumped by either a quadrupled Nd:YAG (266-nm) laser or a KrF excimer laser are studied. The Raman-active gases comprise H2, D2, or CH4, as well as a mixt. of them, with the addn. of He, Ne, or Ar. A parametric study, in which the Stokes conversion efficiency and the beam quality (M2) were measured, was made. The first Stokes efficiency increases and all the Stokes thresholds decrease with an increase in the lens focal length or the M2 parameter of the pump beam. The quality of the St

The eruption of the Icelandic volcano Eyjafjallajokull in April-May 2010 represents a "natural experiment" to study the impact of volcanic emissions on a continental scale. For the first time, quantitative data about the presence, altitude, and layering of ...

Water vapor and temperature spatial distribution and their temporal evolution are among the most important parameters in numerical weather forecasting and climate models. The operational relative humidity/temperature profiling in meteorology is carried out ...

We report direct absorption spectroscopic detection of ozone at ambient pressure with a pulsed, DFB quantum-cascade laser (QCL) tuned within 1044-1050 cm(-1) by temperature scanning. Wavelength calibration curves were derived from FTIR and CO2 spectra and interpreted with respect to the heat transfer from the heterostructure to the sink. The laser linewidth (similar to0.13 cm(-1) FWHM) was found to decrease with temperature, probably as a result of operation at constant current. Spurious spectral features d

Taylor’s frozen turbulence hypothesis is the central assumption invoked in most experiments designed to investigate turbulence physics with time resolving sensors. It is also frequently used in theoretical discussions when linking Lagrangian to Eulerian fl ...

Water vapour has been measured from the International Scientific Station Jungfraujoch (ISSJ, 47° N, 7° E, 3580 in above sea level) during the winters of 1999/2000 and 2000/2001 by microwave radiometry and Raman lidar. The abundance of atmospheric water vapour between the planetary boundary layer and the upper stratosphere varies over more than three orders of magnitude. The currently used measurement techniques are only suited to determine the abundance of water vapour in different atmospheric regimes. None

A new Raman lidar for unattended, round-the-clock measurement of vertical water vapor profiles for operational use by the MeteoSwiss has been developed during the past years by the Swiss Federal Institute of Technology, Lausanne. The lidar uses narrow fiel ...

Preliminary work confirmed the important contribution of regional scale processes on pollutant concns. obsd. at local scales. For Grenoble, France, the model domain for simulations discussed, was selected considering the topog., urban area distribution, boundary conditions, and possible constraints in terms of computing time. The nesting technique used involved calcns. over a larger domain which contained the smaller domain. Two of the most important components of these models are the chem. mechanism and tr

Raman lidars exploit the proportionality between the intensity of scattered by a Raman process laser radiation and the number density of the scattering molecules to derive water vapor mixing ratio profile. Water vapor/air mixing ratio is directly proportio ...

A new lidar for the measurement of tropospheric ozone is proposed, based on the differential analysis of the Raman backscattered signals on nitrogen and oxygen, which is far less sensitive to the aerosols than the classical DIAL system. Using a third Raman channel, the system is able to measure the water vapor mixing ratio simultaneously. The transmitting section of the instrument is composed of a single wavelength at 266 nm, generated by a quadrupled Nd:YAG laser, while the receiving section is the combina

Valentin Simeonov

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Instrumental correction of the uneven PMT aging effect on the calibration constant of a water vapor Raman lidar

Measured and Estimated Water Vapor Advection in the Atmospheric Surface Layer

An investigation of ozone and planetary boundary layer dynamics over the complex topography of Grenoble combining measurements and modeling

Étude d'un épisode photochimique à l'aide d'un modèle méso-échelle et de mesures intensives sur la région de Grenoble

Ozone and water-vapor measurements by Raman lidar in the planetary boundary layer: Error sources and field measurements

Regional levels of ozone in the troposphere over eastern Mediterranean

Study of a photochemical episode over the Grenoble area using a mesoscale model and intensive measurements

Development of a multiwavelength aerosol and water-vapor lidar at the Jungfraujoch Alpine Station (3580 m above sea level) in Switzerland

Translational screening platform to evaluate chemotherapy in combination with focal therapy for retinoblastoma

Coherent structures and the k(-1) spectral behaviour

Experimental investigation of high-power single-pass Raman shifters in the ultraviolet with Nd:YAG and KrF lasers

Four-dimensional distribution of the 2010 Eyjafjallajokull volcanic cloud over Europe observed by EARLINET

Raman lidar in operational meteorology

Ozone detection by differential absorption spectroscopy at ambient pressure with a 9.6 mu m pulsed quantum-cascade laser

The Effect of Scale on the Applicability of Taylor’s Frozen Turbulence Hypothesis in the Atmospheric Boundary Layer

Ground-based water vapour soundings by microwave radiometry and Raman lidar on Jungfraujoch (Swiss Alps)

Raman Lidar for Meteorological Observations, RALMO - Part 1: Instrument description

Measurement campaign and numerical modelling in the complex topography of the Grenoble area (France) during summer '99

Absolutely calibrated Raman lidar as a reference tool in atmospheric humidity profiling

Raman DIAL measurement of ozone and water vapor in the lower troposphere