NASA's Langley Research Center recently completed development of the Aerosol Wind Profiler (AWP) suborbital coherent Doppler wind lidar (CDWL) instrument. Developed with support from NASA's Earth Science Technology Office, Earth Science Division, and LaRC Science Directorate, the AWP project adapted the Wind-SP 2 µm transceiver for airborne use. AWP successfully completed demonstration and engineering test flights in January 2023. LaRC has been funded by a NOAA Joint Venture program Suborbital 3-D Wind Measurement Demonstration project to collect and provide AWP data. The first campaign collected > 50 hours of data during the October 2023 EcoDemonstrator campaign on the NASA DC-8, samples of which will be presented here. AWP implemented and demonstrated multiple technologies needed for a space CDWL transceiver, which have continued development towards miniaturization and ruggedization. A space-based CDWL study is being completed that leverages these recent developments, informing a vision for a relatively low-cost orbital CDWL mission that will also be introduced.

Accurate specification of hurricane inner-core structure is critical to predicting the evolution of a hurricane. However, observations over hurricane inner cores are generally lacking. Previous studies have emphasized Tail Doppler radar (TDR) data assimilation to improve hurricane inner-core representation. Recently, Doppler wind lidar (DWL) has been used as an observing system to sample hurricane inner-core and environmental conditions. The NOAA P3 Hurricane Hunter aircraft has DWL installed and can obtain wind data over a hurricane's inner core when the aircraft passes through the hurricane. In this study, we examine the impact of assimilating DWL winds and TDR radial winds on the prediction of Hurricane Earl (2016) with the NCEP operational Hurricane Weather Research and Forecasting (HWRF) system. A series of data assimilation experiments are conducted with the Gridpoint Statistical Interpolation (GSI)-based ensemble-3DVAR hybrid system to identify the best way to assimilate TDR and DWL data into the HWRF forecast system. The results show a positive impact of DWL data on hurricane analysis and prediction. Compared with the assimilation of u and v components, assimilation of DWL wind speed provides better hurricane track and intensity forecasts. Proper choices of data thinning distances (e.g., 5 km horizontal thinning and 70 hPa vertical thinning for DWL) can help achieve better analysis in terms of hurricane vortex representation and forecasts. In the analysis and forecast cycles, the combined TDR and DWL assimilation (DWL wind speed and TDR radial wind, along with other conventional data, e.g., NCEP Automated Data Processing (ADP) data) offsets the downgrade analysis from the absence of DWL observations in an analysis cycle and outperforms assimilation of a single type of data (either TDR or DWL) and leads to improved forecasts of hurricane track, intensity, and structure. Overall, assimilation of DWL observations has been beneficial for analysis and forecasts in most cases. The outcomes from this study demonstrate the great potential of including DWL wind profiles in the operational HWRF system for hurricane forecast improvement.

One-second-processed three-dimensional position observations transmitted from an instrumented golden eagle were used to determine the detailed long-range flight behavior of the bird. Once elevated from the surface, the eagle systematically used atmospheric gravity waves, first to gain altitude, and then, in multiple sequential glides, to cover over 100 km with a minimum expenditure of its metabolic energy.

Estimating methane (CH4) emission rates using quantitative CH4 retrievals from the Next Generation Airborne Visible/Infrared Imaging Spectrometer (AVIRIS-NG) requires the use of wind speeds. Model wind speeds have limited temporal and spatial resolution, meteorological station wind data are of variable quality and are often not available near observed plumes, and the use of ultrasonic anemometers co-located with methane sources is impractical for AVIRIS-NG flight campaigns with daily coverage of thousands of square kilometers. Given these limitations, this study focused on the use of the Twin Otter Doppler Wind Lidar (TODWL) to measure near surface winds and provide coincident measurements to CH4 plumes observed with AVIRIS-NG. In a controlled release experiment, TODWL observed wind speed and direction agreed well with ultrasonic anemometer measurements and CH4 emission rates derived from TODWL observations were more accurate than those using the ultrasonic anemometer or model winds during periods of stable winds. During periods exhibiting rapid shifts in wind speed and direction, estimating emission rates proved more challenging irrespective of the use of model, ultrasonic anemometer, or TODWL wind data. Overall, TODWL was able to provide reasonably accurate wind measurements and emission rate estimates despite the variable wind conditions and excessive flight level turbulence which impacted near surface measurement density. TODWL observed winds were also used to constrain CH4 emissions at a refinery, landfill, wastewater facility, and dairy digester. At these sites, TODWL wind measurements agreed well with wind observations from nearby meteorological stations, and when combined with quantitative CH4 plume imagery, yielded emission rate estimates that were similar to those obtained using model winds. This study demonstrates the utility of combining TODWL and AVIRIS-NG CH4 measurements and emphasizes the potential benefits of integrating both instruments on a single aircraft for future deployments.

During October–November 2014 and May 2015, NASA sponsored and conducted a pair of airborne campaigns called Polar Winds to investigate atmospheric circulations, particularly in the boundary layer, over the Arctic using NASA’s Doppler Aerosol WiNd (DAWN) lidar. A description of the campaigns, the DAWN instrument, wind retrieval methods and data processing is provided. During the campaigns, the DAWN instrument faced backscatter sensitivity issues in the low aerosol conditions that were fairly frequent in the 2–6 km altitude range. However, when DAWN was able to make measurements, comparisons with dropsondes show good agreement and very low bias and supports the use of an airborne Doppler wind lidar such as DAWN that can provide profiles with high velocity precision, ~65 m vertical resolution and horizontal spacing as fine as 3–7 km. Case study analyses of a Greenland tip jet, barrier winds and an upper level jet are presented and show how, despite sensitivity issues, DAWN data can be confidently used in diagnostic studies of dynamic features in the Arctic. Comparisons with both an operational and research Weather Research and Forecasting (WRF) model for these events also show the potential for utilization in model validation. The sensitivity issues of the DAWN laser have since been corrected.

During 25 May–24 June 2017, NASA’s Doppler Aerosol WiNd (DAWN) lidar was flown on board a NASA DC-8 aircraft as part of the Convective Processes EXperiment (CPEX) airborne campaign based out of Ft. Lauderdale, FL. Central to DAWN’s deployment was the goal of obtaining high time and spatial resolution wind velocity measurements, particularly with respect to the convective life cycle. We describe the processes involved in deriving wind profiles from DAWN observations and evaluate the performance of DAWN in terms of data coverage, resolution and frequency. Comparisons with dropsonde wind measurements show an overall low bias of <0.20 m/s with a RMSD of ~1.6 and R2 > 0.92 for both u and v components for the data set as a whole (over 160 comparisons). From this CPEX experience, we find that the DAWN wind profiles are of high precision, ~30 m vertical resolution and with horizontal spacing as fine as 3–7 km, and rival dropsondes for horizontal wind coverage (aerosols and clouds permitting). Case studies illustrate the benefit of using the DAWN to investigate and characterize the dynamics of the tropical atmosphere over open ocean waters in conditions ranging from undisturbed to active convection.

Fifty years ago the Line Islands Experiment was launched to obtain in situ surface, soundings, and aircraft observations in a convectively active region of the tropical oceans close to the nadir point of the new geosynchronous meteorological satellite. Two related tropical field experiments, in 1968 and 1969, followed in the vicinity of Barbados in the western Atlantic. Component parts of these three field experiments are recalled in this presentation that resonated over the subsequent half century.

In May-June 2017, NASA conducted the airborne 2017 Convective Processes in the Tropics Experiment (CPEX) which utilized the Doppler Aerosol WiNd lidar (DAWN), dropsondes and other remote sensing instruments aboard a NASA DC-8 aircraft to study convective processes and circulations in the tropics. Sixteen NASA DC-8 missions were flown into the Gulf of Mexico, Caribbean Sea, and the Atlantic Ocean where a comprehensive set of observations (particularly winds from DAWN and the dropsondes) were taken near isolated, scattered, and organized deep convection during all phases of the convective life cycle.

Proposed Mission Measurement within clouds The general call for global 3D winds was well documented in the last Decadal survey [NRC, 2007] and the need remains just as strong today if we are to realize the “transformational” advances in NWP and climate modeling. The following recommendation was recently made in NASA’s Workshop Report on Scientific Challenges and Opportunities in the NASA Weather Focus Area :

This paper briefly presents a case for a global wind pathfinder mission using the proven coherent DWL technology as a component in a global wind observing strategy that also includes CMV/AMV, OVW, CYGNSS, near-future small sats, etc. The proposed lower energy per pulse/high PRF coherent DWL addresses the challenge of making precise measurements in the presence of clouds.

One of the most important applications of a space-based Doppler Wind Lidar (DWL) would be to improve atmospheric analyses and weather forecasting. Since the mid-1980s, Observing System Simulation Experiments (OSSEs) have been conducted to evaluate the potential impact of space-based DWL data on numerical weather prediction (NWP). All of these OSSEs have shown significant beneficial impact on global analyses and forecasts. In more recent years, a limited number of experiments have been conducted to evaluate the potential impact of DWL data on hurricane forecasting and also to begin to evaluate the impact of real airborne DWL observations. These latest studies suggest that DWL can complement existing hurricane observations effectively and have the potential to contribute to improved hurricane track and intensity forecasting.

This talk presents analysis of the Doppler Wind Lidar (DWL) measured wind profiles in Tropical Storm (TS) Erika (2015) by NOAA’s P3 aircraft. This work was funded by NOAA’s Sandy Supplemental Program that supports new technologies such as the DWL for hurricane research. It is for the first time, the DWL onboard a NOAA P3 has become operational in hurricane reconnaissance missions and collected highquality wind profile data. The DWL wind profiles were first verified against the collocated dropsonde and Doppler radar observations, showing good agreement. To the authors’ knowledge, the DWL data collected in TS Erika provided the best data coverage in the boundary layer of any given TS. This data set allows us to investigate the detailed boundary layer structure, including the boundary layer height, the strength of the inflow and outflow, and their asymmetric distributions. Composite analysis of the DWL data shows that the axisymmetric boundary layer structure of TS Erika is largely different from that of a typical hurricane from previous dropsonde observations. The vorticity budget conducted using the DWL data suggests that the boundary layer of TS Erika is far from being in vorticity balance. The large magnitude of boundary-layer divergence and the small magnitude of mass flux above the boundary layer may explain why TS Erika did not intensify during the period of observation. The boundary-layer structure asymmetry is found to be tied to the vortex tilt that is induced by the environmental vertical wind shear.

Spatiotemporal variability in the convective boundary layer height z(i) over complex terrain is governed by numerous factors such as land surface processes, topography, and synoptic conditions. Observational datasets to evaluate weather forecast models that simulate this variability are sparse. This study aims to investigate the z(i) spatial variability (along a total leg length of 1800 km) around and over a steep isolated mountain (Granite Mountain) of horizontal and vertical dimensions of 8 and 0.9 km, respectively. An airborne Doppler lidar was deployed on seven flights during the Mountain Terrain Atmospheric Modeling and Observations (MATERHORN) campaign conducted at Dugway Proving Ground (Utah) from 25 September to 24 October 2012. During the afternoon, an east-west z(i) gradient over the region with z(i) that was approximately 200m higher on the eastern side than on the western side of Granite Mountain was observed. This gradient illustrates the impact of two different land surface properties on z(i) spatial variability, with a sparsely vegetated desert steppe region on the east and a dry, bare lake-bed desert with high subsurface soil moisture to the west of Granite Mountain. Additionally, the z(i) spatial variability was partly attributed to the impact of Granite Mountain on the downwind z(i). Differences in z(i) were also observed by the radiosonde measurements in the afternoon but not in the morning as the z(i) variability in morning were modulated by the topography. The high-resolution lidar-derived z(i) measurements were used to estimate the entrainment zone thickness in the afternoon, with estimates ranging from 100 to 250 m.

Abstract Emerging application areas such as air pollution in megacities, wind energy, urban security, and operation of unmanned aerial vehicles have intensified scientific and societal interest in mountain meteorology. To address scientific needs and help improve the prediction of mountain weather, the U.S. Department of Defense has funded a research effort—the Mountain Terrain Atmospheric Modeling and Observations (MATERHORN) Program—that draws the expertise of a multidisciplinary, multi-institutional, and multinational group of researchers. The program has four principal thrusts, encompassing modeling, experimental, technology, and parameterization components, directed at diagnosing model deficiencies and critical knowledge gaps, conducting experimental studies, and developing tools for model improvements. The access to the Granite Mountain Atmospheric Sciences Testbed of the U.S. Army Dugway Proving Ground, as well as to a suite of conventional and novel high-end airborne and surface measurement platforms, has provided an unprecedented opportunity to investigate phenomena of time scales from a few seconds to a few days, covering spatial extents of tens of kilometers down to millimeters. This article provides an overview of the MATERHORN and a glimpse at its initial findings. Orographic forcing creates a multitude of time-dependent submesoscale phenomena that contribute to the variability of mountain weather at mesoscale. The nexus of predictions by mesoscale model ensembles and observations are described, identifying opportunities for further improvements in mountain weather forecasting.