Learn More
In this article, we propose a new stochastic downscaling method: provided a numerical prediction of wind at large scale, we aim to improve the approximation at small scales thanks to a local stochastic model. We first recall the framework of a Lagrangian stochastic model borrowed from S.B. Pope. Then, we adapt it to our meteorological framework, both from(More)
Keywords: MORCE platform Regional Earth system Climate modeling Mesoscale process Impact studies HyMeX ChArMeX MerMeX CORDEX a b s t r a c t The vulnerability of human populations and natural systems and their ability to adapt to extreme events and climate change vary with geographic regions and populations. Regional climate models (RCM), composed by an(More)
A 1.55-microm continuous-wave heterodyne Doppler lidar (HDL) with three receiver-detector units is used to validate experimentally the findings presented in the Guérit et al. companion paper [Appl. Opt. 41, 2232 (2002)] on the effectiveness of independent realizations to improve HDL performance (velocity or power estimates or both) at a low carrier-to-noise(More)
An optical technique is described that determines the path-averaged value of a refractive-index structure parameter at 10.6 microm by use of a pulsed coherent CO(2) lidar in direct detection and hard-target returns. The lidar measurements are compared with measurements taken by a 0.9-microm scintillometer and temperature probe (with humidity corrections).(More)
It is shown that the performance of heterodyne Doppler lidar (HDL) can be improved by (i) at least one good realization for every single shot or (ii) several simultaneous good realizations for accumulation. Until now, several simultaneous independent realizations at high carrier-to-noise ratio (CNR) have been considered. At low CNR, noise may have a(More)
A two-mode CO(2) laser is used as transmitter in a 10-microm heterodyne Doppler lidar (HDL) to take advantage of a spectral diversity technique, i.e., independent realizations obtained with different spectral components. The objective is to improve the properties (i.e., less variance) of power returns from a hard target. The statistical properties are(More)
It has been observed that the West African monsoon onset is concomitant with the enhancement of the Saharan heat low. We show here through a combined diagnostic and modeling study a possible interaction between northern Africa orography and the deepening of the Saharan heat low at the time of the monsoon onset. The amplification of an anticyclonic(More)
There have been many analyses of the reduction of lidar system efficiency in bistatic geometry caused by beam spreading and by fluctuations along the two paths generated by refractive-index turbulence. Although these studies have led to simple, approximate results that provide a reliable basis for preliminary assessment of lidar performance, they do not(More)