A Leonardo Skiron3D Doppler lidar has recently been acquired with the aim of providing wind measurement at Amsterdam Schiphol Airport for research purposes and operational services for aviation meteorology. As an initial step, the lidar is placed at the research site of Cabauw, the Netherlands for intercomparison with a WindCube 200s lidar and in-situ mast wind measurements. The Skiron3D is operated in velocity-azimuth display (VAD) mode, while the WindCube 200s uses a Doppler Beam Swing (DBS) strategy to provide vertical profiles of wind speed and direction. A nearby 213m high mast provides a platform for in-situ wind measurements using cup anemometers, wind vanes. This work presents the comparison of the vertical profiles of both lidars. The lowest measuring heights of the wind lidars are additionally compared with the in-situ measurements in the mast.

Over the past decade, the Royal Netherlands Meteorological Institute (KNMI) has undertaken significant effort to integrate emerging surface-based remote sensing technology in its services for operations and research. KNMI deploys several types of ground-based lidar instruments to detect clouds and volcanic ash, and measure vertical profiles of aerosols, wind and water vapor. Real-time information on the vertical structure of the atmosphere is becoming increasingly important input for nowcasting purposes and models supporting KNMI’s forecasting, climate, early warning, maritime, and energy tasks.Since the late 1990’s KNMI deploys automatic lidar ceilometers (ALC) for continuous (24/7), fully automated observations of cloud base height and cloud cover. These ALCs are integrated in our nationwide automatic weather station network and currently consists of 45 stations, including civil and defense airports and North Sea platforms. ALC backscatter profile data provides aerosol layer information, including the boundary layer and elevated aerosol layers, allowing to monitor Sahara dust, wildfire smoke and volcanic ash. Those different types of aerosols can be differentiated with the Raman lidars at the Cabauw atmospheric research station, part of the Ruisdael Observatory and ACTRIS National Facility. One Raman lidar also measures vertical profiles of the water vapor mixing ratio. The KNMI ALCs are part of the European ALC network within E-PROFILE. Current research focuses on the real-time retrieval of boundary layer height from ALC backscatter data and its transition from research to operations (R2O). The ground-based lidars at Cabauw play a significant role in validation of space-born lidars, such as EarthCARE.Since end 2010’s KNMI uses Doppler lidars that measure wind. The development of wind farms on the Dutch North Sea provided the opportunity to deploy short-range wind lidars offshore. The current network consists of 7 stations, within 4 wind farms. The measured wind profiles are made available to key users, including the wind farm operators and KNMI forecasters, in near-real time. At Cabauw, a long-range scanning Doppler lidar provides vertical profiles of horizontal wind and vertical velocity in the boundary layer, from which for instance low-level jets, mixing height and gravity waves are detected. It is part of the European DWL network within E-PROFILE. More recently, KNMI deployed a long-range scanning Doppler lidar for research and operational deployment at Amsterdam Schiphol Airport, supporting KNMI’s aviation services. Research includes the development of aircraft wake vortex persistence monitoring or alerting systems for dangerous wind phenomena such as wind shear or gust fronts.Here we will present an overview of KNMI’s ground-based lidar activities, along with an outlook on future developments and opportunities.

Abstract We present observations of atmospheric gravity waves (AGW) on the Dutch North Sea, using short-range wind lidars that are deployed within offshore wind farms for operational wind measurements. This weather phenomenon can lead to high-amplitude oscillations in the wind speed and wind direction with a period of a few minutes, and therefore impact wind energy. As an example we show wind lidar data for the AGW event of 2025-05-02, with observations from six stations within four wind farms ( Borssele, Hollandse Kust Zuid, Hollandse Kust Noord and Hollandse Kust West ). We also show backscatter profiles from collocated automatic lidar ceilometers that shed light on the vertical extent of the AGW. Our observations can contribute in the understanding of the impact of AGWs on wind farm performance.

We present observations of a gravity wave (GW) event over the Netherlands and Belgium in the night and early morning of 30 June 2022. This event was captured by instruments that are part of the meteorological observational network of The Netherlands and Belgium, including the operational weather radars and automatic lidar ceilometers, and by the (tower) in situ and Doppler lidar at the Cabauw atmospheric research station. Together they provide 3D information on the GW event, with detailed information on the vertical profiles from Cabauw, and the spatial extent and evolution from the observational synoptic network. Two distinct GW trains were observed, both interpreted as ducted GW that are trapped in the lowermost 500 m of the stable nocturnal boundary layer. The GWs showed large vertical velocity amplitudes up to 3 m/s, resulting in strong modulations of wind, temperature, humidity and pressure. By comparing our observations to the Copernicus European Regional ReAnalysis (CERRA) wind and temperature fields, we interpret that these GWs were generated by convergence lines over Belgium and the North Sea that was linked to an occlusion front.

Short-range vertical profiling wind lidars are extensively used in the context of wind energy. These instruments measure wind profiles up to 200-300 m and their 10-minute averaged wind products are commonly used. Here we discuss their ability to observe atmospheric gravity waves (GW), using the unaveraged data. Trapped GWs in the stable boundary layer that propagate horizontally can result in a strong modulation of wind (and other meteorological variables) with periods similar or smaller than 10 minutes. These periods are such that GWs might be missed in the standard wind lidar data products. In general, the measurements of vertical velocity profiles are the most suitable for GW detection and characterization, while the horizontal wind profiles directly link to the possible impact on wind energy.Here we consider the ZX300M (ZX Lidars) wind lidar, which is operationally deployed on offshore platforms within the Dutch offshore wind farms [1]. The ZX300M is a continuous-wave focusing vertical profiling wind lidar. It measures horizontal wind speed, wind direction and vertical velocity in a range of 10 m to 300 m above the instrument, using velocity azimuth display (VAD) scans of 1 second and a scanning cone angle of 30° (with respect to zenith). Up to 11 heights are measured sequentially.To demonstrate the ability to observe GWs with these instruments we have identified two GW events, in the stable nocturnal boundary layer, during the two-year measurement campaign of the ZX300M wind lidar at our atmospheric supersite Cabauw in 2018-2020 [2]. We compare the unaveraged ZX300M data with in-situ wind measurements in the 213-m tall mast, in particular the vertical velocity as measured by 3D sonic anemometers. We observe a high correlation between the ZX300M wind lidar and in-situ measurements for those GW events. We conclude that the ZX300M nicely captures those GWs, limited by its maximum range of 300 m.Finally, we present our first GW observations from the operational ZX300M instruments within the offshore wind farms. We highlight the GW event on 2022-05-19 observed at platforms Borssele Alpha and Borssele Beta (7 km apart) within offshore wind farm Borssele. Our growing offshore network of wind lidars provided a unique opportunity to detect offshore gravity waves and study their impact on the offshore wind energy.[1] Knoop, S. and de Jong, M.: Wind lidars within Dutch offshore wind farms, EMS 2023, https://doi.org/10.5194/ems2023-271[2] Knoop, S., Bosveld, F. C., de Haij, M. J., and Apituley, A.: A 2-year intercomparison of continuous-wave focusing wind lidar and tall mast wind measurements at Cabauw, Atmos. Meas. Tech., 14, 2219, 2021, https://doi.org/10.5194/amt-14-2219-202

A scanning Doppler lidar, the Windcube200S (Vaisala/Leosphere), has been operating at our research site Cabauw since April 2021, to provide detailed measurements of the wind field, aerosols and clouds, in the framework of Ruisdael Observatory [1]. First measurements mainly focused on operational wind profiling (based on DBS scans). The phenomenon of the triplet storm in February 2022 (Dudley, Eunice, Franklin) was nicely captured by the Doppler lidar. Synergy with a Doppler cloud radar was demonstrated, providing wind profiles up and within clouds [2]. Doppler lidar wind profiles can also be combined with the in situ wind measurements in the tall mast up to 200m, for instance for low-level jet studies and climatology. In this presentation we focus on a measurement campaign we performed in the summer of 2022 (June 21 to August 21), which was aimed to study the convective boundary layer. For this the Doppler lidar continuously performed vertical stare scans with an accumulation time of 1 s, interrupted each hour with 10 minutes of wind profiling (DBS scans) and a low-elevation azimuth scan (PPI) of 3 minutes. The vertical stare data nicely show the up- and downdrafts, together with the formation and presence of (shallow cumulus) clouds. We show a direct comparison between the vertical velocity data and high resolution large eddy simulations and numerical weather prediction model simulations, and discuss the possibilities in model development and validation. From the vertical stare data also turbulence characteristics, such as the variance and dissipation rate, can be extracted. From the variance the mixing height can be derived. We will apply a retrieval method of the vertical wind speed variance and dissipation rate including the effect of probe volume of the Doppler lidar [3], which we will validate by sonic measurements in the tall mast. [1] https://ruisdael-observatory.nl/ [2] José Dias Neto, Louise Nuijens, Christine Unal, and Steven Knoop, Combined wind lidar and cloud radar for high-resolution wind profiling, Earth Syst. Sci. Data 15, 769, 2023, https://doi.org/10.5194/essd-15-769-2023 [3] Banakh, Smalikho, Falits, Sherstobitov, Estimating the Parameters of Wind Turbulence from Spectra of Radial Velocity Measured by a Pulsed Doppler Lidar, Remote Sens. 13, 2071, 2021, https://doi.org/10.3390/rs1311207

This paper introduces an experimental setup for retrieving horizontal wind speed and direction profiles with a high temporal and vertical resolution for process studies and validation of convection-permitting model simulations. The CMTRACE (tracing convective momentum transport in complex cloudy atmospheres) campaign used collocated wind lidar and cloud radar measurements to retrieve seamless wind profiles from near the surface up to cloud tops. It took place in Cabauw, the Netherlands, between 13 September and 3 October 2021. The intermediate processing steps for generating the level 1 and level 2 data, such as second trip echoes filtering, offset correction, wind retrieval, re-gridding, and flagging, are described. In level 1 (https://doi.org/10.5281/zenodo.6926483, Dias Neto, 2022a), the data from lidar and radars are kept in the original spatial and temporal resolution, while in level 2 (https://doi.org/10.5281/zenodo.6926605, Dias Neto, 2022b), they are regridded to a common spatial and temporal resolution. Statistical analyses of the lidar's and radar's wind speed and direction profiles indicate a correlation higher than 0.95 for both variables. The bias of wind direction and speed calculated between radar's and lidar's observations are 0.24∘ and −0.16 m s−1, respectively. The foreseen initial application of the datasets includes the study of convective momentum transport and its validation in regional weather forecasts and large-eddy simulation hindcasts.

The Ruisdael Observatory [1] is a national initiative, a nationwide observatory for measurements of the atmosphere. It is set up to enable more concrete, detailed forecasts of the weather and air quality. The Ruisdael Observatory, named after the 17th century painter Jacob van Ruisdael, famous for his cloudy skies, will be modelling the entire Dutch atmosphere with a high resolution of only 100m. At the Cabauw site, which fulfils the role of main station within the Ruisdael Observatory, a large set of instruments is operated to study the atmosphere and its interaction with the land surface. Doppler wind lidars, which are laser-based remote sensing instruments, will provide detailed measurements of the wind field, aerosols and clouds around the Cabauw site.We have installed a scanning long-range Doppler lidar Windcube 200S (Leosphere/Vaisala) at the Cabauw site at April 6th, 2021. This instrument operates at a laser wavelength of 1.5 µm and retrieves return signals mainly from aerosol backscatter. Therefore the wind measurements are typically limited to the boundary layer, although higher lying clouds up to 14km can also provide data. The instrument has full semi-hemisphere scanning capabilities and the principle measurands are the radial wind speed, i. e. the wind component along the line-of-sight, and the relative attenuated backscatter coefficient. Wind profiles of horizontal wind speed and wind direction are retrieved from specific scan modes.During its first year at Cabauw the Doppler lidar has operated continuously, alternating between different scan modes and instrument parameters, This included all standard Windcube scan modes: RHI (Range Height Indicator) for elevation scans at fixed azimuth angle, PPI (Plan Position Indicator) for azimuth scans at a fixed elevation angle, DBS (Digital Beam Swing) to retrieve wind profiles, and vertical staring. In addition, the six-beam method for retrieving wind and turbulence profiles [2] have been applied. During two campaign periods the Doppler lidar was co-located with Doppler cloud radars to investigate possible synergy between the retrieved wind profiles. Also a co-located ceilometer (Lufft CHM15K) is present, being part of the automatic weather station at Cabauw, which can be helpful in interpreting the Doppler lidar data.Among the topics that are investigated: * intercomparison with the in situ wind measurements in the tall meteorological tower at 200m * comparison DBS and six-beam wind profiling scan modes * presence of range ambiguity and its consequences on the chosen resolution * vertical velocity information from DBS and continuous vertical staring scan modes * PPI and RHI scans for (LES-)model evaluationHere we will present some results of those studies, and our plans towards a long-term operational measuring program.[1] https://ruisdael-observatory.nl/[2] A six-beam method to measure turbulence statistics using ground-based wind lidars, Sathe, Mann, Vasiljevic, and Lea, Atmos. Meas. Tech., 8, 729 (2015)

Convective clouds may be associated with substantial transport of momentum. The process of convective momentum transport is typically investigated using simulations due to a lack of observations. This study exploits the currently available remote sensing techniques to visualize wind structures within clouds and their surroundings and quantify the vertical transport of momentum. The Tracing Convective Momentum Transport in Complex Cloudy Atmospheres experiment (CMTRACE) took place in the experimental site in Cabauw (The Netherlands) between September 13th and October 3rd 2021, as part of the RUISDAEL project. The goal of CMTRACE was to provide continuous profiles of horizontal and vertical wind components with a temporal resolution of ~1 minute and vertical resolution of ~50 m within the cloud and sub-cloud layers to improve our understanding of the role of momentum transport on different scales. One scanning wind lidar provided the observations in the sub-cloud layer, while in the cloud layer, the observations were obtained by one scanning and one vertically pointing cloud radar. The high-resolution data produced by those instruments across the boundary layer can also benefit data assimilation and model evaluation. During CMTRACE, we sampled various cloud regimes such as non-precipitating shallow cumulus, deep convective clouds and stratiform clouds. Due to the presence of insects, the radar provided almost identical wind profiles to the lidar up to cloud base, giving us confidence in the quality of the observations. The dataset was also validated against the data from radiosondes and the Cabauw mast tower. In this presentation, we outline the CMTRACE observational dataset and present statistical analyses and classification of the data into different cloud regimes. The profiles of wind fluctuations and momentum fluxes are used to exemplify correlations between vertical and horizontal wind on both cloud- and mesoscale scales.

Atmospheric visibility, or meteorological optical range (MOR), is governed by light extinction by aerosols. State-of-the-art visibility sensors, such as employed in meteorological observatories and airports, infer MOR by measuring either transmittance or scattering. While these sensors yield robust measurements with reasonable accuracy (10 % to 20 %), they measure in situ. MOR from these sensors may thus not be representative of MOR further away, for example, under conditions with stratified aerosol types. This includes off-shore sites near the sea surface during conditions with advection fog, sea spray or mist. Elastic backscatter lidar can be used to measure light extinction and has previously demonstrated to be a powerful method to infer visibility. Lidar can measure visibility not just near the instrument but also further away (remotely) and single-ended whilst also being capable of measuring profiles of MOR along atmospheric slant paths. Continuous-wave (CW) Doppler wind lidar systems make up one of the most widespread type of elastic backscatter lidar and are typically used in wind resource assessment. Using these existing platforms for remote and single-ended measurement of MOR profiles could allow for new and valuable applications. However, the low-light extinction associated with this type of lidar excludes the use of the extinction coefficient for MOR retrieval but leaves the backscatter coefficient as a possible proxy for MOR, though with an accuracy expected to be inferior to the former method. We analysed backscatter data from CW wind lidar and co-measured MOR from visibility sensors from two campaigns (Cabauw, Netherlands, and Pershore, United Kingdom) and found backscatter from CW wind lidar to be a viable proxy of MOR if calibrated against a visibility sensor. The expected accuracy of the method is low and of the order of few kilo-metres. This means MOR from CW wind lidar could be used in safety-uncritical problems, such as assessment of visibility of manmade objects, including wind turbines.

. This paper introduces an experimental setup for retrieving horizontal wind speed and direction profiles by combining wind lidar and cloud radars and the 2 level datasets produced. The experiment took place in Cabauw, the Netherlands, between September 13 th and October 3 rd 2021. The intermediate processing steps for generating the Level 1 and Level 2 data, such as second trip echos filtering, offset correction, wind retrieval, re-gridding and flagging, are described. In Level 1 (https://doi.org/10.5281/zenodo.6926483, Dias Neto (2022a)), the data from lidar and radars are kept in the original spatial 5 and temporal resolution, while in Level 2 (https://doi.org/10.5281/zenodo.6926605, Dias Neto (2022b)), they are re-grided to a common spatial and temporal resolution. Statistical analyses of the lidar’s and radar’s wind speed and direction profiles indicate a correlation higher than 0.95 for both variables, and the bias of wind direction and speed are 0.24 ◦ and -0.16 ms − 1 , respectively. Applications of this dataset include numerical model validation, momentum transport studies and spectral analysis for different cloud regimes.

A 2-year measurement campaign of the ZephIR 300 vertical profiling continuous-wave (CW) focusing wind lidar has been carried out by the Royal Netherlands Meteorological Institute (KNMI) at the Cabauw site. We focus on the (height-dependent) data availability of the wind lidar under various meteorological conditions and the data quality through a comparison with in situ wind measurements at several levels in the 213 m tall meteorological mast. We find an overall availability of quality-controlled wind lidar data of 97 % to 98 %, where the missing part is mainly due to precipitation events exceeding 1 mm h−1 or fog or low clouds below 100 m. The mean bias in the horizontal wind speed is within 0.1 m s−1 with a high correlation between the mast and wind lidar measurements, although under some specific conditions (very high wind speed, fog or low clouds) larger deviations are observed. The mean bias in the wind direction is within 2∘, which is of the same order as the combined uncertainty in the alignment of the wind lidars and the mast wind vanes. The well-known 180∘ error in the wind direction output for this type of instrument occurs about 9 % of the time. A correction scheme based on data of an auxiliary wind vane at a height of 10 m is applied, leading to a reduction of the 180∘ error below 2 %. This scheme can be applied in real-time applications in the situation that a nearby freely exposed mast with wind direction measurements at a single height is available.

Atmospheric motion and turbulence are essential parameters for weather and topics related to air quality. Therefore, wind profile measurements play an important role in atmospheric research and meteorology. One source of wind profile data are Doppler wind lidars, which are laser-based remote sensing instruments that measure wind speed and wind direction up to a few hundred meters or even a few kilometers. Commercial wind lidars use the laser wavelength of 1.5 µm and therefore backscatter is mainly from aerosols while clear air backscatter is minimal, limiting the range to the boundary layer typically. We have carried out a two-year intercomparison of the ZephIR 300M (ZX Lidars) short-range wind lidar and tall mast wind measurements at Cabauw [1]. We have focused on the (height-dependent) data availability of the wind lidar under various meteorological conditions and the data quality through a comparison with in situ wind measurements at several levels in the 213m tall meteorological mast. We have found an overall availability of quality-controlled wind lidar data of 97% to 98 %, where the missing part is mainly due to precipitation events exceeding 1 mm/h or fog or low clouds below 100 m. The mean bias in the horizontal wind speed is within 0.1 m/s with a high correlation between the mast and wind lidar measurements, although under some specific conditions (very high wind speed, fog or low clouds) larger deviations are observed. This instrument is being deployed within North Sea wind farms. Recently, a scanning long-range wind lidar Windcube 200S (Leosphere/Vaisala) has been installed at Cabauw, as part of the Ruisdael Observatory program [2]. The scanning Doppler wind lidars will provide detailed measurements of the wind field, aerosols and clouds around the Cabauw site, in coordination with other instruments, such as the cloud radar. [1] Knoop, S., Bosveld, F. C., de Haij, M. J., and Apituley, A.: A 2-year intercomparison of continuous-wave focusing wind lidar and tall mast wind measurements at Cabauw, Atmos. Meas. Tech., 14, 2219–2235, 2021 [2] https://ruisdael-observatory.nl/

Abstract. A two-year measurement campaign of the ZephIR 300 vertical profiling continuous-wave (CW) focusing wind lidar has been carried out by the Royal Netherlands Meteorological Institute (KNMI) at the Cabauw site. We focus on the (height-dependent) data availability of the wind lidar under various meteorological conditions and the data quality through a comparison with in situ wind measurements at several levels in the 213-m tall meteorological mast. We find an overall availability of quality controlled wind lidar data of 97 % to 98 %, where the missing part is mainly due to precipitation events exceeding 1 mm/h or fog or low clouds below 100 m. The mean bias in the horizontal wind speed is within 0.1 m/s with a high correlation between the mast and wind lidar measurements, although under some specific conditions (very high wind speed, fog or low clouds) larger deviations are observed. The mean bias in the wind direction is within 2°, which is on the same order as the combined uncertainty in the alignment of the wind lidars and the mast wind vanes. The well-known 180° error in the wind direction output for this type of instrument occurs about 9 % of the time. A correction scheme based on data of an auxiliary wind vane at a height of 10 m is applied, leading to a reduction of the 180° error below 2 %. This scheme can be applied in real-time applications in case a nearby, freely exposed, mast with wind direction measurements at a single height is available.

We thank Referee #1 for his or her compliments and interesting comments on our paper. We now will reply to the comments one by one. Intended changes to the manuscript are explicitly mentioned. (1) Line 25: "Coherent lidars also measure the shift of the frequency spectrum, albeit by a different methodology." Probably this boils down to the question whether measuring a beat-signal is the same as measuring a shift of the frequency spectrum. However, what we had in mind is that

The Dutch Offshore Wind Atlas (DOWA) is validated against wind speed and direction measurements from the Cabauw meteorological mast for a 10-year period and at heights between 10 m and 200 m. The validation results are compared to the Royal Netherlands Meteorological Institute (KNMI) North Sea Wind (KNW) atlas. It is found that the average difference (bias) between DOWA wind speeds and those measured at Cabauw varies for the different heights between −0.1 m/s to 0.3 m/s. Significant differences between DOWA and KNW are only found at altitudes of 10 m and 20 m, where KNW performs better. For heights above 20 m, there is no significant difference between DOWA and KNW with respect to the 10-year averaged wind speed bias. The diurnal cycle is better captured by DOWA compared to KNW, and the hourly correlation is slightly improved. In addition, a comparison with the global European Center for Medium-Range Weather Forecasts (ECMWF) ERA-Interim and ERA5 reanalyses (used for KNW and DOWA, respectively) is made, highlighting the added skill provided by downscaling those global datasets with the weather model HARMONIE.

A two-year verification campaign of the ZephIR~300 vertical profiling wind LiDAR has recently been started by the Royal Netherlands Meteorological Institute (KNMI) at the CESAR Observatory (Cabauw Experimental Site for Atmospheric Research) in Cabauw, The Netherlands. In this paper we present preliminary results of the first six months of this campaign (February 14 - July 31, 2018), focusing on the (height-dependent) data availability of the ZephIR~300 under various meteorological conditions (precipitation intensity, cloud base height and visibility) and the data quality via a comparison with in situ wind measurements at several levels in the 213-m tall meteorological mast.

We report on the realization of an ultracold (<25 μK) mixture of rubidium (87Rb) and metastable triplet helium (4He) in an optical dipole trap. Our scheme involves laser cooling in a dual-species magneto-optical trap, simultaneous MW- and RF-induced forced evaporative cooling in a quadrupole magnetic trap, and transfer to a single-beam optical dipole trap. We observe long trapping lifetimes for the doubly spin-stretched spin-state mixture and measure much shorter lifetimes for other spin-state combinations. We discuss prospects for realizing quantum degenerate mixtures of alkali-metal and metastable helium atoms.

In an ultracold, optically trapped mixture of $^{87}$Rb and metastable triplet $^4$He atoms we have studied trap loss for different spin-state combinations, for which interspecies Penning ionization is the main two-body loss process. We observe long trapping lifetimes for the purely quartet spin-state combination, indicating strong suppression of Penning ionization loss by at least two orders of magnitude. For the other spin-mixtures we observe short lifetimes that depend linearly on the doublet character of the entrance channel. We compare the extracted loss rate coefficient with recent predictions of multichannel quantum-defect theory for reactive collisions involving a strong exothermic loss channel and find near-universal loss for doublet scattering. Our work demonstrates control of reactive collisions by internal atomic state preparation, which also implies magnetic field tunability.

In an ultracold, optically trapped mixture of Rb-87 and metastable triplet He-4 atoms we have studied trap loss for different spin-state combinations, for which interspecies Penning ionization is the main two-body loss process. We observe long trapping lifetimes for the purely quartet spin-state combination, indicating strong suppression of Penning-ionization loss by at least two orders of magnitude. For the other spin mixtures we observe short lifetimes that depend linearly on the doublet character of the entrance channel. We compare the extracted loss rate coefficient with recent predictions of multichannel quantum-defect theory for reactive collisions involving a strong exothermic loss channel and find near-universal loss for doublet scattering. Our work demonstrates control of Penning-ionization reactive collisions by internal atomic state preparation.