<p>We compare the wind measurements of a virtual tower triple Doppler Lidar setup to those of a sonic anemometer located at a height of 90 m above ground on an instrumented tower and with those of a single Doppler Lidar. The instruments were set up at the boundary-layer field site of the German Meteorological Service (DWD) in July and August of 2020 during the FESST@MOL (Field Experiment on sub-mesoscale spatio-temporal variability at the Meteorological Observatory Lindenberg) 2020 campaign.  The triple Lidar setup was operated in a stare and in a step/stare mode at six heights between 90 and 500 m above ground, while the single Lidar was operated in a continuous scan Velocity-Azimuth-Display (VAD) mode with an azimuthal resolution of around 1.5 ° and a zenith angle of 55.5 °. Overall, both Lidar methods showed a good agreement for the whole study period for different averaging times and scan modes compared to the sonic anemometer. Additionally, we developed and show a new filtering approach based on a Median Absolute Deviation (MAD) filter for the virtual tower setup and compare it to a filtering approach based on a signal-to-noise ratio SNR threshold. The advantage of the MAD filter is that it is not based on a strict threshold but on the MAD of each 30-second period and can, therefore, better adapt to changing atmospheric conditions. In the comparison the MAD filter leads to a greater data availability while upholding similar comparability and bias values between the triple Lidar and sonic anemometer setups. Our results also show that a single Doppler Lidar is a viable method for measuring wind speed and direction with only small disadvantages, at least for measurement heights similar to our investigation and for comparable heterogeneous but flat landscapes.</p>

This study provides methane (CH4) emission estimates for mature female African beef cattle in a semi-arid region in Southern Kenya using open-path laser spectroscopy together with a backward Lagrangian Stochastic (bLS) dispersion modeling technique. We deployed two open-path lasers to determine 10-min averages of line-integrated CH4 measurements upwind and downwind of fenced enclosures (so-called bomas: a location where the cattle are gathered at night) during 14 nights in September/October 2019. The measurements were filtered for wind direction deviations and friction velocity before the model was applied. We compared the obtained emission factors (EFs) with the Intergovernmental Panel on Climate Change (IPCC) Tier 1 estimates for the Sub-Saharan African (SSA) countries, which were mostly derived from studies carried out in developed countries and adapted to the conditions in Africa. The resulting EF of 75.4 ± 15.99 kg year−1 and the EFs calculated from other studies carried out in Africa indicate the need for the further development of region-specific EFs depending on animal breed, livestock systems, feed quantity, and composition to improve the IPCC Tier 1 estimates.

This study provides methane (CH4) emission estimates for mature female African beef cattle in a semi-arid region in Southern Kenya using open-path laser spectroscopy together with a backward Lagrangian Stochastic (bLS) dispersion modeling technique. We deployed two open-path lasers to determine 10-minute averages of line-integrated CH4 measurements upwind and downwind of fenced enclosures (so-called bomas: a location where the cattle are gathered at nighttime) during 14 nights in September/October 2019. The measurements were filtered for wind direction deviations and friction velocity before the model was applied. We compared the obtained emission factors (EFs) with the Intergovernmental Panel on Climate Change (IPCC) Tier 1 estimates for the Sub-Saharan African (SSA) countries, which were mostly derived from studies carried out in developed countries and adapted to the conditions in Africa. The resulting mean EF of 75.4 ± 5.69 kg yr-1 and the EFs calculated from other studies carried out in Africa differ considerably from each other, which indicates the need for the further development of region-specific EFs to improve the IPCC Tier 1 estimates.

<p>Technology has reached a point where ground-based remote sensing instruments have the ability to greatly increase the spatial and temporal data density compared to conventional instruments. This offers the great opportunity to improve the understanding of individual processes and to increase the predictive capabilities of numerical weather models and reduce their inaccuracies. The goal of this study is to assess these measurement inaccuracies and the usefulness of Doppler lidar systems for these purposes. The data were collected during the FESST@MOL 2020 measurement campaign, organised by the German Weather Service (DWD) and initiated by the Hans-Ertel-Center for Weather Research (HErZ), at the boundary layer field site (GM) of the DWD in Falkenberg (Tauche), Germany. During the measurement campaign, a total of eight Doppler lidars of the brands Halo Photonics and Leosphere were active in different operating modes. We compare the results of triple and single Halo Photonics lidar setups and triple Leosphere lidar setups with the measurements of an ultrasonic anemometer mounted at a height of 90 m at the 99 m high instrumented tower in Falkenberg. The focus of the operating modes was on various virtual tower (VT) measurements and velocity azimuth display (VAD) measurements with the different averaging times of ten and thirty minutes for the mean horizontal wind. The discrepancy in readings between VT and VAD measurements increases with increasing height above the ground while the Halo Photonic lidars performed better in the comparison with the sonic anemometer.</p>

<p>The technological development of ground-based active remote sensing instruments has reached a point where they have the possibility to drastically increase the temporal and spatial data density compared to conventional instruments, which would allow for a better process understanding and is expected to enhance the forecasting skills of numerical weather prediction systems and reduce its uncertainties. To test the measurement uncertainty and feasibility of Doppler Lidar systems we participated in the FESST@MOL 2020 field campaign, organized by the German Meteorological Service (DWD) in Lindenberg, Germany. During this campaign, eight Doppler Lidars were operated at the boundary layer field site (GM) Falkenberg. We evaluated different scanning strategies for the determination of the wind profile in the Atmospheric Boundary Layer (ABL) using multiple different triple Lidar virtual tower (VT) scan patterns including range height indicator (RHI) and step/stare scan modes. We compared these Lidar-based wind measurements with the data from a sonic anemometer on a 99 m tall instrumented tower also located in Falkenberg over a period of four months. The lidar and the sonic anemometer data were processed to 10- and 30- minute averages and compared to each other. The VT measurements underestimated the mean horizontal wind compared to the sonic anemometer by around 0.2 m s<sup>‑1</sup>. Besides that, we compared the VT data with those from a single fourth nearby Doppler Lidar which was running in a velocity-azimuth display (VAD) mode. The calculated mean horizontal wind values between the two different modes showed a good comparability but differed stronger with increasing height.</p>