The three-dimensional global wind field is the most important remaining measurement needed to accurately assess the dynamics of the atmosphere. Wind information in the tropics, high latitudes, and stratosphere is particularly deficient. Furthermore, only a small fraction of the atmosphere is sampled in terms of wind profiles. This limits our ability to optimally specify initial conditions for numerical weather prediction (NWP) models and our understanding of several key climate change issues. Because of its extensive wind measurement heritage (since 1968) and especially the rapid recent technology advances, Doppler lidar has reached a level of maturity required for a space-based mission. The European Space Agency (ESA)'s Atmospheric Dynamics Mission Aeolus (ADM-Aeolus) Doppler wind lidar (DWL), now scheduled for launch in 2015, will be a major milestone. This paper reviews the expected impact of DWL measurements on NWP and climate research, measurement concepts, and the recent advances in technology that ...

LIDAR-MEASURED WIND PROFILES The Missing Link in the Global Observing System

Convective self-aggregation, the spontaneous organization of initially scattered convection into isolated convective clusters despite spatially homogeneous boundary conditions and forcing, was first recognized and studied in idealized numerical simulations. While there is a rich history of observational work on convective clustering and organization, there have been only a few studies that have analyzed observations to look specifically for processes related to self-aggregation in models. Here we review observational work in both of these categories and motivate the need for more of this work. We acknowledge that self-aggregation may appear to be far-removed from observed convective organization in terms of time scales, initial conditions, initiation processes, and mean state extremes, but we argue that these differences vary greatly across the diverse range of model simulations in the literature and that these comparisons are already offering important insights into real tropical phenomena. Some preliminary new findings are presented, including results showing that a self-aggregation simulation with square geometry has too broad distribution of humidity and is too dry in the driest regions when compared with radiosonde records from Nauru, while an elongated channel simulation has realistic representations of atmospheric humidity and its variability. We discuss recent work increasing our understanding of how organized convection and climate change may interact, and how model discrepancies related to this question are prompting interest in observational comparisons. We also propose possible future directions for observational work related to convective aggregation, including novel satellite approaches and a ground-based observational network.

/pdf/observing-convective-aggregation-2qayphm7vb.pdf

Observing Convective Aggregation

The impact of Aeolus wind retrievals on ECMWF global weather forecasts

. Soon after the launch of Aeolus on 22 August 2018, the first ever wind lidar in space developed by the European Space Agency (ESA) has been providing profiles of the component of the wind vector along the instrument's line of sight (LOS) on a global scale. In order to validate the quality of Aeolus wind observations, the German Aerospace Center (Deutsches Zentrum fur Luft- und Raumfahrt e.V., DLR) recently performed two airborne campaigns over central Europe deploying two different Doppler wind lidars (DWLs) on board the DLR Falcon aircraft. The first campaign – WindVal III – was conducted from 5 November 2018 until 5 December 2018 and thus still within the commissioning phase of the Aeolus mission. The second campaign – AVATARE (Aeolus Validation Through Airborne Lidars in Europe) – was performed from 6 May 2019 until 6 June 2019. Both campaigns were flown out of the DLR site in Oberpfaffenhofen, Germany, during the evening hours for probing the ascending orbits. All together, 10 satellite underflights with 19 flight legs covering more than 7500 km of Aeolus swaths were performed and used to validate the early-stage wind data product of Aeolus by means of collocated airborne wind lidar observations for the first time. For both campaign data sets, the statistical comparison of Aeolus horizontal line-of-sight (HLOS) observations and the corresponding wind observations of the reference lidar (2  µm  DWL) on board the Falcon aircraft shows enhanced systematic and random errors compared with the bias and precision requirements defined for Aeolus. In particular, the systematic errors are determined to be 2.1 m s −1 (Rayleigh) and 2.3 m s −1  (Mie) for WindVal III and −4.6  m s −1 (Rayleigh) and −0.2  m s −1  (Mie) for AVATARE. The corresponding random errors are determined to be 3.9 m s −1  (Rayleigh) and 2.0 m s −1  (Mie) for WindVal III and 4.3 m s −1  (Rayleigh) and 2.0 m s −1  (Mie) for AVATARE. The Aeolus observations used here were acquired in an altitude range up to 10 km and have mainly a vertical resolution of 1 km (Rayleigh) and 0.5 to 1.0 km (Mie) and a horizontal resolution of 90 km (Rayleigh) and down to 10 km (Mie). Potential reasons for those errors are analyzed and discussed.

/pdf/first-validation-of-aeolus-wind-observations-by-airborne-4suykfjsow.pdf

First validation of Aeolus wind observations by airborne Doppler wind lidar measurements

Soon after its successful launch in August 2018,
the spaceborne wind lidar ALADIN (Atmospheric
LAser Doppler INstrument) on-board ESA's
Earth Explorer satellite Aeolus has demonstrated
to provide atmospheric wind profiles on a global
scale. Being the first ever Doppler Wind Lidar
(DWL) instrument in space, ALADIN contributes
to the improvement in numerical weather
prediction (NWP) by measuring one component
of the horizontal wind vector. The performance of
the ALADIN instrument was assessed by a team
from ESA, DLR, industry, and NWP centers
during the first months of operation. The current
knowledge about the main contributors to the
random and systematic errors from the instrument
will be discussed. First validation results from an
airborne campaign with two wind lidars on-board
the DLR Falcon aircraft will be shown.

/pdf/initial-assessment-of-the-performance-of-the-first-wind-4p3t1dfns4.pdf

Initial Assessment of the Performance of the First Wind Lidar in Space on Aeolus

Measurements of winds throughout the atmosphere are crucial for both numerical weather prediction and for climate studies. Nevertheless, observations of height profiles of the global wind field are lacking. Thus the European Space Agency decided to establish a Doppler wind lidar mission named Atmospheric Dynamics Mission ADM-Aeolus. The mission will provide vertical profiles from ground up to the lower stratosphere of one component of the horizontal wind vector, which is perpendicular to the flight track. Pre-launch validation of the instrument with an airborne prototype was performed by DLR.

Oliver Reitebuch

Papers

The Spaceborne Wind Lidar Mission ADM-Aeolus