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The planetary boundary layer height (PBLH) is an essential parameter for weather forecasting and climate modeling. The primary methods for obtaining the PBLH include radiosonde measurements of atmospheric parameters and lidar measurements, which track aerosol layers in the lower atmosphere. Radiosondes provide the parameters to determine the PBLH but cannot monitor changes over a diurnal cycle. Lidar instruments can track the temporal variability of the PBLH and account for spatial variability when operated in a network configuration. The networkable micropulse DIAL (MPD) instruments for thermodynamic profiling are based on diode-laser technology that is eye-safe and cost-effective and has demonstrated long-term autonomous operation. We present a retrieval algorithm for determining the PBLH from the quantitative aerosol profiling capability of the high spectral resolution channel of the MPD. The PBLH is determined using a Haar wavelet transform (HWT) method that tracks aerosol layers in the lower atmosphere. The PBLH from the lidar is compared with the PBLH determined from potential temperature profiles from radiosondes. In many cases, good agreement among the PBLH retrievals was seen. However, the radiosonde retrieval often missed the lowest inversion layer when several layers were present, while the HWT could track the lowest layer.
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Performance Modeling of a Diode-Laser-Based Direct Detection Doppler Lidar for Vertical Wind Profiling
Abstract Micropulse differential absorption lidar (MPD) for water vapor, temperature, and aerosol profiling have been developed, demonstrated, and are addressing the needs of the atmospheric science community for low-cost ground-based networkable instruments capable of long-term monitoring of the lower troposphere. The MPD instruments use a diode-laser-based (DLB) architecture that can easily be adapted for a wide range of applications. In this study, a DLB direct detection Doppler lidar based on the current MPD architecture is modeled to better understand the efficacy of the instrument for vertical wind velocity measurements with the long-term goal of incorporating these measurements into the current network of MPD instruments. The direct detection Doppler lidar is based on a double-edge receiver that utilizes two Fabry-Perot interferometers and a vertical velocity retrieval that requires the ancillary measurement of the backscatter ratio, which is the ratio of the total backscatter coefficient to the molecular backscatter coefficient. The modeling in this paper accounts for the major sources of error. It indicates that the vertical velocity can be retrieved with an error of less than 0.56 m s −1 below 4 km with a 150-m range resolution and an averaging time of five minutes.
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- Award ID(s):
- 1917851
- PAR ID:
- 10354841
- Date Published:
- Journal Name:
- Journal of Atmospheric and Oceanic Technology
- ISSN:
- 0739-0572
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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A collaborative research effort by Montana State University and the National Center for Atmospheric Research has led to the development of a MicroPulse DIAL (MPD) instruments for water vapor profiling, aerosol profiling, boundary layer structure, and temperature profiling of the lower troposphere. The MPD instruments utilize a diode-laser-based instrument architecture, have demonstrated long-term autonomous network operation, and have the potential to address the needs of the science community for networkable ground-based thermodynamic profilers that can provide data in near real time. In this chapter, the recent improvements to the temperature retrieval using the MPD instruments are discussed and initial results from the improved temperature retrieval algorithm are presented.more » « less
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null (Ed.)Abstract The maximum upward vertical velocity at the leading edge of a density current is commonly <10 m s−1. Studies of the vertical velocity, however, are relatively few, in part owing to the dearth of high-spatiotemporal-resolution observations. During the Plains Elevated Convection At Night (PECAN) field project, a mobile Doppler lidar measured a maximum vertical velocity of 13 m s−1 at the leading edge of a density current created by a mesoscale convective system during the night of 15 July 2015. Two other vertically pointing instruments recorded 8 m s−1 vertical velocities at the leading edge of the density current on the same night. This study describes the structure of the density current and attempts to estimate the maximum vertical velocity at their leading edges using the following properties: the density current depth, the slope of its head, and its perturbation potential temperature. The method is then be applied to estimate the maximum vertical velocity at the leading edge of density currents using idealized numerical simulations conducted in neutral and stable atmospheres with resting base states and in neutral and stable atmospheres with vertical wind shear. After testing this method on idealized simulations, this method is then used to estimate the vertical velocity at the leading edge of density currents documented in several previous studies. It was found that the maximum vertical velocity can be estimated to within 10%–15% of the observed or simulated maximum vertical velocity and indirectly accounts for parameters including environmental wind shear and static stability.more » « less
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Abstract. The micropulse differential absorption lidar (MPD) was developed at Montana State University (MSU) and the National Center for Atmospheric Research (NCAR) to perform range-resolved water vapor (WV) measurements using low-power lasers and photon-counting detectors. The MPD has proven to produce accurate WV measurements up to 6 km altitude. However, the MPD's ability to produce accurate higher-altitude WV measurements is impeded by the current standard differential absorption lidar (DIAL) retrieval methods. These methods are built upon a fundamental methodology that algebraically solves for the WV using the MPD forward models and noisy observations, which exacerbates any random noise in the lidar observations. The work in this paper introduces the adapted Poisson total variation (PTV) specifically for the MPD instrument. PTV was originally developed for a ground-based high spectral resolution lidar, and this paper reports on the adaptations that were required in order to apply PTV on MPD WV observations. The adapted PTV method, coined PTV-MPD, extends the maximum altitude of the MPD from 6 to 8 km and substantially increases the accuracy of the WV retrievals starting above 2 km. PTV-MPD achieves the improvement by simultaneously denoising the MPD noisy observations and inferring the WV by separating the random noise from the non-random WV. An analysis with 130 radiosonde (RS) comparisons shows that the relative root-mean-square difference (RRMSE) of WV measurements between RS and PTV-MPD exceeds 100 % between 6 and 8 km, whereas the RRMSE between RS and the standard method exceeds 100 % near 3 km. In addition, we show that by employing PTV-MPD, the MPD is able to extend its useful range of WV estimates beyond that of the ARM Southern Great Plains Raman lidar (RRMSE exceeding 100 % between 3 and 4 km); the Raman lidar has a power-aperture product 500 times greater than that of the MPD.more » « less
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Abstract Macroscopic stratospheric aerosol properties such as surface area density (SAD) and volume density (VD) are required by modern chemistry climate models. These quantities are in continuous need of validation by observations. Direct observation of these parameters is not possible, but they can be derived from optical particle counters (OPCs) which provide concentration (number density) and size distributions of aerosol particles, and possibly from ground‐based and satellite‐borne lidar observations of particle backscatter coefficients and aerosol type. When such measurements are obtained simultaneously by OPCs and lidars, they can be used to calculate backscatter and extinction coefficients, as well as SAD and VD. Empirical relations can thus be derived between particle backscatter coefficient, extinction coefficient, and SAD and VD for a variety of aerosols (desert dust, maritime aerosols, stratospheric aerosols) and be used to approximate SAD and VD from lidar measurements. Here we apply this scheme to coincident measurements of polar stratospheric clouds above McMurdo Station, Antarctica, by ground‐based lidar and balloon‐borne OPCs. The relationships derived from these measurements will provide a means to obtain values of SAD and VD for supercooled ternary solutions (STS) and nitric acid trihydrate (NAT) PSCs from the backscatter coefficients measured by lidar. Coincident lidar and OPC measurements provided 15 profile comparisons. Empirical expressions of SAD and VD as a function of particle backscatter coefficient,β, were calculated from fits of the form log(SAD/VD) = A + Blog(β) usingβfrom the lidar and SAD/VD from the OPC. The PSCs were classified as STS and NAT mixtures, ice being absent.more » « less
- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1175/JTECH-D-22-0001.1
