The water vapour intercomparison effort in the framework of the Convective and Orographically‐induced Precipitation Study: airborne‐to‐ground‐based and airborne‐to‐airborne lidar systems

From Lagrangian back trajectories it was found that the dust was mobilized from sources in Mauritania six days earlier, while the dry layer subsided over the north Atlantic. Off the Moroccan coasts, the dry layer folded down beneath the dusty air mass and the two-layer structure was advected to the Rhine valley in about two days. By heating the atmosphere, the dust layer changed the static stability of the atmosphere and thus the occurrence of convection. A study of sensitivity to the radiative effect of dust showed a better prediction of precipitation when a dust prognostic scheme was used rather than climatology or when dust effects were ignored. This result suggests that dust episodes that occur prior to convective events might be important for quantitative precipitation forecasts.

Section: Quantitative Evaluation Of Dustmentioning

confidence: 98%

Long‐range transport of Saharan dust and its radiative impact on precipitation forecast: a case study during the Convective and Orographically‐induced Precipitation Study (COPS)

Chaboureau

Richard

Pinty

et al. 2011

“…Frequent overpasses are necessary to identify potential instrumental biases with good accuracy, as the data from the remote-sensing instruments are averaged in space and time and different air masses are sampled during these airborne/ground-based intercomparisons. Results are presented in Bhawar et al (2011).…”

Section: Data Archive Quality Control and Key Data Setsmentioning

confidence: 99%

The Convective and Orographically‐induced Precipitation Study (COPS): the scientific strategy, the field phase, and research highlights

Wulfmeyer

Behrendt

Kottmeier

et al. 2011

192

135

Within the framework of the international field campaign COPS (Convective and Orographically-induced Precipitation Study), a large suite of state-of-the-art meteorological instrumentation was operated, partially combined for the first time. This includes networks of in situ and remote-sensing systems such as the Global Positioning System as well as a synergy of multi-wavelength passive and active remote-sensing instruments such as advanced radar and lidar systems. The COPS field phase was performed from 01 June to 31 August 2007 in a low-mountain area in southwestern Germany/eastern France covering the Vosges mountains, the Rhine valley and the Black Forest mountains. The collected data set covers the entire evolution of convective precipitation events in complex terrain from their initiation, to their development and mature phase until their decay. Eighteen Intensive Observation Periods with 37 operation days and eight additional Special Observation Periods were performed, providing a comprehensive data set covering different forcing conditions. In this article, an overview of the COPS scientific strategy, the field phase, and its first accomplishments is given. Highlights of the campaign are illustrated with several measurement examples. It is demonstrated that COPS research provides new insight into key processes leading to convection initiation and to the modification of precipitation by orography, in the improvement of quantitative precipitation forecasting by the assimilation of new observations, and in the performance of ensembles of convection-permitting models in complex terrain.

“…The vertical resolution of the data is 300 m and the temporal resolution is 5 s which corresponds to a horizontal distance of just 875 m between independent profiles. Detailed intercomparisons of the measurements of the different lidar systems during aircraft overpasses were performed by Bhawar et al (2011) with the COPS dataset, similar to those done by Behrendt et al (2007aBehrendt et al ( , 2007b for IHOP 2002. They found that the water-vapour measurements of LEANDRE II, UHOH DIAL and BASIL agree very well.…”

Section: Soundings With Lidar Aircraft and Radiosondesmentioning

confidence: 99%

“…Crook, 1996;Weckwerth, 2000;Fabry, 2006). Especially, the suite of ground-based and airborne watervapour lidars employed during COPS is an excellent tool for this purpose because the data show both high temporal and spatial resolution and high accuracy (Bhawar et al, 2011). In order to study the relation of different observations with each other, composite images of several datasets were made.…”

Section: Introductionmentioning

confidence: 99%

Observation of convection initiation processes with a suite of state‐of‐the‐art research instruments during COPS IOP 8b

Behrendt

Pal

Aoshima

et al. 2011

Self Cite

106

In the afternoon of 15 July 2007, a thunderstorm was initiated within a line of cumulus clouds which formed parallel to the crest of the Black Forest mountains during the Intensive Observation Period (IOP) 8b of the Convective and Orographicallyinduced Precipitation Study (COPS). This paper extends the analysis of processes that led to convection initiation (CI), i.e. the transition from shallow to deep convection, on this day with the data from several COPS instruments that have not been considered in previous studies. In particular, the boundary-layer structure, lids and the water-vapour field in the pre-convective environment of the event are discussed. For this purpose, we investigated measurements of water-vapour lidars, temperature lidars and wind lidars, profiles from radiosondes, in situ aircraft data and gridded data of weather stations as well as GPS integrated-water-vapour data and satellite imagery. Thermally driven circulation systems formed over both the Black Forest and the Vosges mountain ranges which resulted in local convergence zones. These superimposed with the large-scale convergence in the Black Forest area. In the presence of sufficient moisture and updraught, clouds formed close to the mountain crests. The related latent-heat release allowed larger thermals to be produced, which may have had a positive feedback on stabilizing these convergence zones as a whole. We believe that differences in the moisture field explain why convection remained shallow and sparse over the Vosges mountains because these differences were responsible for differences in convective inhibition (CIN). The stationary location of the convergence zone over the southern Black Forest was probably decisive for CI because it constantly transported sensible and latent heat into the area in which CI took place.