Abstract. We present the results of a 1-year quasioperational testing of the 1.5 µm StreamLine Doppler lidar developed by Halo Photonics from 2 October 2012 to 2 October 2013. The system was configured to continuously perform a velocity-azimuth display scan pattern using 24 azimuthal directions with a constant beam elevation angle of 75 • . Radial wind estimates were selected using a rather conservative signal-to-noise ratio based threshold of −18.2 dB (0.015). A 30 min average profile of the wind vector was calculated based on the assumption of a horizontally homogeneous wind field through a Moore-Penrose pseudoinverse of the overdetermined linear system. A strategy for the quality control of the retrieved wind vector components is outlined for ensuring consistency between the Doppler lidar wind products and the inherent assumptions employed in the wind vector retrieval. Quality-controlled lidar measurements were compared with independent reference data from a collocated operational 482 MHz radar wind profiler running in a four-beam Doppler beam swinging mode and winds from operational radiosonde measurements. The intercomparison results reveal a particularly good agreement between the Doppler lidar and the radar wind profiler, with root mean square errors ranging between 0.5 and 0.7 m s −1 for wind speed and between 5 and 10 • for wind direction. The median of the half-hourly averaged wind speed for the intercomparison data set is 8.2 m s −1 , with a lower quartile of 5.4 m s −1 and an upper quartile of 11.6 m s −1 .

A strongly tilted, nearly axisymmetric vortex in dry air with asymmetric diabatic heating is analysed here by matched asymptotic expansions. The vortex is in gradient wind balance, with vortex Rossby numbers of order unity, and embedded in a quasigeostrophic (QG) background wind with weak vertical shear. With wind speeds of 60-120 km h −1, such vortices correspond to tropical storms or nascent hurricanes according to the Saffir-Simpson scale. For asymmetric heating, nonlinear coupling of the evolution equations for the vortex tilt, its core structure, and its influence on the QG background is found. The theory compares well with the established linear theory of precessing quasi-modes of atmospheric vortices, and it corroborates the relationship between vortex tilt and asymmetric potential temperature and vertical velocity patterns as found by Jones (Q. J. R. Meteorol. Soc., vol. 121, 1995, pp. 821-851) and Frank & Ritchie (Mon. Weath. Rev., vol. 127, 1999, pp. 2044-2061 in simulations of adiabatic tropical cyclones. A relation between the present theory and the local induction approximation for three-dimensional slender vortex filaments is established.

An extended version of the Integrated Profiling Technique (IPT) is presented. The IPT combines measurements from cloud radar and microwave radiometer (MWR) with prior information in a 1D‐Var approach in order to retrieve physically consistent atmospheric profiles of temperature, absolute humidity, liquid water content (LWC), and recently also cloud droplet effective radius (REF). Physical consistency implies the reproducibility of the measurements within the uncertainties. Results based on synthetic observations revealed a good retrieval performance with a high convergence rate of 98%. Retrieval uncertainties are typically around 0.06 g m−3 for LWC and 0.6 μm for REF. For the application to real measurements, quality‐controlled, bias‐free observations are crucial. A newly developed MWR spectral consistency check, which was applied to the measurements at the Jülich Observatory for Cloud Evolution (JOYCE), revealed strongly bias‐affected channels. The IPT itself can serve as a further quality check: particularly in clear‐sky cases, nonconvergence or physically inconsistent solutions may hint at measurement offset errors. Based on sensitivity studies, the final set of MWR frequencies was identified and the retrieval applied to 1 year of data. Physically consistent solutions could be found in 62% of all processed cases. A focus was put on the analysis of nondrizzling single‐layer water clouds which typically have small geometrical thicknesses (<300 m), low liquid water paths (<50 g m−2), and small REF (<5 μm). The retrieved data product contains a high potential for the analysis of warm cloud characteristics and, in combination with auxiliary information from the JOYCE instrumentation, of associated boundary layer processes.

Abstract. The retrieval of turbulence parameters with profiling Doppler wind lidars (DWLs) is of high interest for boundary layer meteorology and its applications. DWLs provide wind measurements above the level of meteorological masts while being easier and less expensive to deploy. Velocity-azimuth display (VAD) scans can be used to retrieve the turbulence kinetic energy (TKE) dissipation rate through a fit of measured azimuth structure functions to a theoretical model. At the elevation angle of 35.3∘ it is also possible to derive TKE. Modifications to existing retrieval methods are introduced in this study to reduce errors due to advection and enable retrievals with a low number of scans. Data from two experiments are utilized for validation: first, measurements at the Meteorological Observatory Lindenberg–Richard-Aßmann Observatory (MOL-RAO) are used for the validation of the DWL retrieval with sonic anemometers on a meteorological mast. Second, distributed measurements of three DWLs during the CoMet campaign with two different elevation angles are analyzed. For the first time, the ground-based DWL VAD retrievals of TKE and its dissipation rate are compared to in situ measurements of a research aircraft (here: DLR Cessna Grand Caravan 208B), which allows for measurements of turbulence above the altitudes that are in range for sonic anemometers. From the validation against the sonic anemometers we confirm that lidar measurements can be significantly improved by the introduction of the volume-averaging effect into the retrieval. We introduce a correction for advection in the retrieval that only shows minor reductions in the TKE error for 35.3∘ VAD scans. A significant bias reduction can be achieved with this advection correction for the TKE dissipation rate retrieval from 75∘ VAD scans at the lowest measurement heights. Successive scans at 35.3 and 75∘ from the CoMet campaign are shown to provide TKE dissipation rates with a good correlation of R>0.8 if all corrections are applied. The validation against the research aircraft encourages more targeted validation experiments to better understand and quantify the underestimation of lidar measurements in low-turbulence regimes and altitudes above tower heights.

Abstract. The retrieval of turbulence parameters with profiling Doppler wind lidars (DWL) is of high interest for boundarylayer meteorology and its applications. The DWL measurements extend beyond the observations with meteorological masts and are comparably flexible in their installation. Velocity-azimuth display (VAD) type scans can be used to retrieve turbulence kinetic energy (TKE) dissipation rate through a fit of measured azimuth structure functions to a theoretical model. At the elevation angle of 35.3° it is also possible to derive TKE. We show in this study how modifications to existing methods allow to retrieve TKE and its dissipation rate even with a small number of scans, how a simple correction for advection improves the results at low altitudes and that VAD scans at different elevation angles with the same instrument provide comparable results of TKE dissipation rate after all filters and corrections. For this purpose, data of two experiments are utilized: First, measurements at the Observatory Lindenberg – Richard-Aßmann Observatory (MOL-RAO) are used for validation of the DWL retrieval with sonic anemometers on a meteorological mast. Second, distributed measurements of three DWL during the CoMet campaign are analyzed and compared to in-situ measurements of the DLR Cessna Grand Caravan 208B. The comparison to in-situ instruments shows that the methods to improve turbulence retrievals from VAD scans introduced in this study are effective, especially at low altitudes and for narrow cone angles, but it also shows the limits of turbulence measurement with state-ofthe-art DWL in low turbulence regimes.