Sara Cushman Tucker

Extended depth of field and aberration control for inexpensive digital microscope systems.

We present a new application and current results for extending depth of field using wave front coding. A cubic phase plate is used to code wave fronts in microscopy resulting in extended depths of field and inexpensive chromatic aberration control. A review of the theory behind cubic phase plate extended depth of field systems is given along with the challenges that are face when applying the theory to microscopy. Current results from the new extended depth of field microscope systems are shown.

Doppler Lidar Estimation of Mixing Height Using Turbulence, Shear, and Aerosol Profiles

Abstract The concept of boundary layer mixing height for meteorology and air quality applications using lidar data is reviewed, and new algorithms for estimation of mixing heights from various types of lower-tropospheric coherent Doppler lidar measurements are presented. Velocity variance profiles derived from Doppler lidar data demonstrate direct application to mixing height estimation, while other types of lidar profiles demonstrate relationships to the variance profiles and thus may also be used in the mixing height estimate. The algorithms are applied to ship-based, high-resolution Doppler lidar (HRDL) velocity and backscattered-signal measurements acquired on the R/V Ronald H. Brown during Texas Air Quality Study (TexAQS) 2006 to demonstrate the method and to produce mixing height estimates for that experiment. These combinations of Doppler lidar–derived velocity measurements have not previously been applied to analysis of boundary layer mixing height—over the water or elsewhere. A comparison of the ...

Horizontal Velocity and Variance Measurements in the Stable Boundary Layer Using Doppler Lidar: Sensitivity to Averaging Procedures

Abstract Quantitative data on turbulence variables aloft—above the region of the atmosphere conveniently measured from towers—have been an important but difficult measurement need for advancing understanding and modeling of the stable boundary layer (SBL). Vertical profiles of streamwise velocity variances obtained from NOAA’s high-resolution Doppler lidar (HRDL), which have been shown to be approximately equal to turbulence kinetic energy (TKE) for stable conditions, are a measure of the turbulence in the SBL. In the present study, the mean horizontal wind component U and variance σ2u were computed from HRDL measurements of the line-of-sight (LOS) velocity using a method described by Banta et al., which uses an elevation (vertical slice) scanning technique. The method was tested on datasets obtained during the Lamar Low-Level Jet Project (LLLJP) carried out in early September 2003, near the town of Lamar in southeastern Colorado. This paper compares U with mean wind speed obtained from sodar and sonic an...

Observing System Simulation Experiments (OSSEs) to Evaluate the Potential Impact of an Optical Autocovariance Wind Lidar (OAWL) on Numerical Weather Prediction

AbstractThe potential impact of Doppler wind lidar (DWL) observations from a proposed optical autocovariance wind lidar (OAWL) instrument is quantified in observing system simulation experiments (OSSEs). The OAWL design would provide profiles of useful wind vectors along a ground track to the left of the International Space Station (ISS), which is in a 51.6° inclination low-Earth orbit (LEO). These observations are simulated realistically, accounting for cloud and aerosol distributions inferred from the OSSE nature runs (NRs), and measurement and sampling error sources. The impact of the simulated observations is determined in both global and regional OSSE frameworks. The global OSSE uses the ECMWF T511 NR and the NCEP operational Global Data Assimilation System at T382 resolution. The regional OSSE uses an embedded hurricane NR and the NCEP operational HWRF data assimilation system with outer and inner domains of 9- and 3-km resolution, respectively.The global OSSE results show improved analyses and fore...

Platform-Motion Correction of Velocity Measured by Doppler Lidar

Abstract The NOAA/Earth System Research Laboratory (ESRL) has two coherent Doppler lidar systems that have been deployed on board research vessels to obtain data during several experiments. The instruments measure the wind velocity relative to the motion of the lidar; therefore, correction for the motion of the platform is required. This article gives a thorough analysis of the correction for lidar velocity measurements. The analysis is general enough to be applied to Doppler velocity measurements from all monostatic ship- and aircraftborne lidars and radars, and generalization to bistatic systems is achievable. The correction is demonstrated using miniature master-oscillator power-amplifier (mini-MOPA) Doppler velocity data obtained during the Rain in Cumulus over the Ocean (RICO) experiment.

The Optical Autocovariance Wind Lidar. Part I: OAWL Instrument Development and Demonstration

AbstractWe present the motivation, instrument concept, hardware descriptions, and initial validation testing for a Doppler wind lidar (DWL) system that uses optical autocovariance (OA) in a field-w...

Benefits of a quadrature Mach Zehnder interferometer as demonstrated in the Optical Autocovariance Wind and Lidar (OAWL) wind and aerosol measurements

With internal research and development (IRAD) and NASA Earth Science Technology Office (ESTO) funding, Ball Aerospace has developed the HSRL (high spectral resolution lidar) for Aerosols Winds and Clouds using the Optical Autocovariance Wind Lidar (HAWC-OAWL) – a Doppler wind lidar system to measure winds and aerosol levels from aerosol backscatter. The Doppler receiver uses a Quadrature Mach Zehnder Interferometer (QMZI) receiver that measures changes in fringe phase (e.g. Doppler induced changes in laser frequency) and fringe amplitude (illumination coherence length). Airborne flight tests in 2016 demonstrated the performance of a two-look version of the system in making line-of-sight (LOS) wind measurements and in retrieving horizontal vector wind estimates from aircraft. Subsequently, ground-tests alongside NCAR’s HSRL system providing known aerosol profiles demonstrated that the instrument performance model accurately predicts the measurement uncertainty. The system has since been reconfigured for the DC-8 aircraft to include two-looks, two-wavelengths and depolarization measurements. Current ground-based studies at Ball Aerospace are focused on demonstrating HSRL measurements with HAWC-OAWL using the QMZI ability to measure fringe amplitude as well as phase. The combined HSRL and winds measurement enables studies of aerosol transport as well as impacts of winds on cloud formations. We will review the QMZI theory and present preliminary results of HSRL data products from ground-based measurements.