Remote Sensing of Tropical Cyclones: Applications from Microwave Radiometry and Global Navigation Satellite System Reflectometry

Tropical cyclones (TCs) are important to observe, especially over the course of their lifetimes, most of which is spent over the ocean. Very few in situ observations are available. Remote sensing has afforded researchers and forecasters the ability to observe and understand TCs better. Every remote sensing platform used to observe TCs has benefits and disadvantages. Some remote sensing instruments are more sensitive to clouds, precipitation, and other atmospheric constituents. Some remote sensing instruments are insensitive to the atmosphere, which allows for unobstructed observations of the ocean surface. Observations of the ocean surface, either of surface roughness or emission can be used to estimate ocean surface wind speed. Estimates of surface wind speed can help determine the intensity, structure, and destructive potential of TCs. While there are many methods by which TCs are observed, this thesis focuses on two main types of remote sensing techniques: passive microwave radiometry and Global Navigation Satellite System reflectometry (GNSS-R). First, we develop and apply a rain rate and ocean surface wind speed retrieval algorithm for the Hurricane Imaging Radiometer (HIRAD). HIRAD, an airborne passive microwave radiometer, operates at C-band frequencies, and is sensitive to rain absorption and emission, as well as ocean surface emission. Motivated by the unique observing geometry and high gradient rain scenes that HIRAD typically observes, a more robust rain rate and wind speed retrieval algorithm is developed. HIRAD’s observing geometry must be accounted for in the forward model and retrieval algorithm, if high rain gradients are to be estimated from HIRAD’s observations, with the ultimate goal of improving surface wind speed estimation. Lastly, TC science data products are developed for the Cyclone Global Navigation Satellite System (CYGNSS). The CYGNSS constellation employs GNSS-R techniques to estimate ocean surface wind speed in all precipitating conditions. From inputs of CYGNSS level-2 wind speed observations and the storm center location, a variety of products are created: integrated kinetic energy, wind radii, radius of maximum wind speed, and maximum wind speed. These products provide wind structure and intensity information—valuable for situational awareness and science applications.PHDAtmospheric, Oceanic & Space ScienceUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/137109/1/marygm_1.pd

Control of unsteady separated flow associated with the dynamic stall of airfoils

An effort to understand and control the unsteady separated flow associated with the dynamic stall of airfoils was funded for three years through the NASA cooperative agreement program. As part of this effort a substantial data base was compiled detailing the effects various parameters have on the development of the dynamic stall flow field. Parameters studied include Mach number, pitch rate, and pitch history, as well as Reynolds number (through two different model chord lengths) and the condition of the boundary layer at the leading edge of the airfoil (through application of surface roughness). It was found for free stream Mach numbers as low as 0.4 that a region of supersonic flow forms on the leading edge of the suction surface of the airfoil at moderate angles of attack. The shocks which form in this supersonic region induce boundary-layer separation and advance the dynamic stall process. Under such conditions a supercritical airfoil profile is called for to produce a flow field having a weaker leading-edge pressure gradient and no leading-edge shocks. An airfoil having an adaptive-geometry, or dynamically deformable leading edge (DDLE), is under development as a unique active flow-control device. The DDLE, formed of carbon-fiber composite and fiberglass, can be flexed between a NACA 0012 profile and a supercritical profile in a controllable fashion while the airfoil is executing an angle-of-attack pitch-up maneuver. The dynamic stall data were recorded using point diffraction interferometry (PDI), a noninvasive measurement technique. A new high-speed cinematography system was developed for recording interferometric images. The system is capable of phase-locking with the pitching airfoil motion for real-time documentation of the development of the dynamic stall flow field. Computer-aided image analysis algorithms were developed for fast and accurate reduction of the images, improving interpretation of the results

Lab-on-a-tissue : optimization of on-tissue chemistry for improved mass spectrometry imaging

The work presented in this thesis describes the improvement and application of on-tissue chemistry for in-situ biomolecular analysis using matrix assisted-laser desorption/ionization mass spectrometry imaging (MALDI-MSI). We have proposed new methodologies, applying on-tissue (enzymatic) chemistry, to increase the molecular information obtained in a MALDI-MSI analysis. We have also developed an automated histology-guided MSI platform, based on state-of-the-art image processing tools, to facilitate high mass and spatial resolution MALDI-MSI while maintaining reasonable data loads and acquisition times. We have shown the importance of these methods in a clinical biomarker discovery study on myxoid liposarcoma tissues. ZonMWLUMC / Geneeskund

Quantifying various thunderstorm characteristics during high impact events using radar and satellite observations

Climate change is expected to change the intensity and frequency of heavy storms. Thus, understanding different characteristics of this phenomena (i.e., intensity, size, speed, direction, etc.) is vital for the effective climate adaptation. Many extreme storms have small areas and short lifetimes (sub-daily/hourly) and can have destructive impacts, especially over urban areas. Therefore, it is vital to understand the nature of changes in these extremes to reduce the risk of their destructive impacts on cities. The overarching goal of this thesis is to quantify various storm characteristics, including their changes, using radar and satellite observations. Using an object-based technique, I compare the Integrated Multi-Satellite Retrievals for Global Precipitation Measurement (IMERG) and ground radar based Multi-Radar Multi-Sensor Quantitative Precipitation Estimates (MRMS) over the United States and show that the object-based storm properties are not sensitive to the observational platforms. However, there are differences that are statistically significant. Secondly, I investigate the error sources associated with different types of contributing data in the IMERG during the hurricane days occurred in 2016-2018 with MRMS as the reference. The results show that IMERG have better agreement with MRMS during the passive microwave (PMW) observations compared to rainfall estimates come from the combination of the interpolation techniques and infrared observations (morph/IR). Also, the quality of morph/IR estimates deteriorates with the longer absence of PMW observations. Thirdly, I establish an object-based climatology of rain systems using radar data near Sydney, Australia. The results show that rain systems in different seasons have distinct object-based characteristics, and these differences are dependent on their source of origins and also their positions over land and ocean. Using a two-step clustering algorithm, I have found five system types over Sydney peaking in different seasons. While overall rainfall statistics don't show any link to climate modes, links do appear for some system types using a multivariate approach. Finally, I show that there is a robust increasing trend of 20% per decade in sub-hourly extreme rainfall in the Sydney region over 20 years, despite no evidence of trends on hourly or daily scales. I am able to obtain this new result via a novel analysis of long-term radar data, including cross-checking between neighboring radars

Climate Change and Air Pollution Relationships. Lessons from a Subtropical Desert Region

The Atacama Desert is the dryest desert on Earth. Atmospheric, ocean, and topographic forcings preserve an exceptional hyper-arid environment. As a product of anthropogenic and natural emissions, PM10 and PM2.5 atmospheric concentrations have been observed to exceed international standards in urban areas where about 1.5 million people live. This research starts by describing the climate dynamics in northern Chile along with the primary anthropogenic emission sources of PM10, PM2.5, and gaseous precursor pollutants. Then, air quality levels across urban areas are evidenced. As a major source of natural PM, the unexplored mineral dust cycle of the Atacama desert is studied from satellite retrievals of aerosols properties. Two areas in the Antofagasta region are identified as predominant sources of dust, where links with reanalysed wind patterns are reported. This study is followed by the analysis of the relationship between PM10-PM2.5 levels and atmospheric ventilation from observational and modelled datasets. Because of the significant link found between both, especially in coastal areas, a wheater-driven model for PM events, with atmospheric ventilation as the most significant input variable, is pro- posed for the coastal city of Antofagasta. Finally, the future of the Atacama Desert, comprising atmospheric and oceanic regional forcings and future PM10-PM2.5 levels, is explored from the UKESM1 model. The South Pacific Anticyclone is already extending and intensifying during the austral summertime. The above leads to increasing upwelling-favourable winds and coastal upwelling intensity of the Humboldt system at the surface ocean, enhancing atmospheric stability. However, a decline is simulated at deeper ocean layers. PM10-PM2.5 are both projected to increase under the SSP370 and SSP585 climate change experiments during the 21st Century. This increasing trend is more abrupt under the SSP370 than the SSP585 experiment due to increased SO2 and dust emissions and the absence of mitigation measurements. Policy implications are dis- cussed, and future academic research is proposed, including implications beyond academia

CIRA annual report FY 2016/2017

Reporting period April 1, 2016-March 31, 2017

Broadband Long-wave Infrared Few-cycle Pulse Generation via Optical Parametric Chirped-pulse Amplification

Intense ultrashort laser sources in the Long-Wave Infrared (LWIR) spectral range are needed to gain a deeper understanding of many laser-matter interaction processes in laser pulse filamentation, strong-field physics, and laser-driven particle acceleration. Ultrashort LWIR pulses are also valuable in supporting applications in molecular spectroscopy, such as the investigations of molecular dynamics. However, the lack of suitable broadband laser gain media prevents the generation of the intense ultrashort LWIR pulses directly from laser oscillators and amplifiers, with the gaseous CO2 laser being the only exception. The high cost and footprint of the advanced terawatt power level CO2 systems with relatively long picosecond pulse duration hinders their wide application. Optical Parametric Chirped-Pulse Amplification (OPCPA) is the most promising method for intense few-cycle pulse generation in the LWIR range. OPCPA uses an instantaneous nonlinear optical process–Optical Parametric Amplification (OPA) in a Chirped-Pulse Amplification (CPA) system to boost the energy of broadband ultrashort pulses. Mid-Infrared (MIR) OPCPA has reached peak powers on the order of several gigawatts, but when extended to the LWIR regime using near-infrared pumping, less than gigawatt powers have been produced. Generating radiation in the LWIR range reduces the conversion efficiency due to unfavorably higher quantum defect and thus requires higher-energy, nanosecond MIR pump lasers. To address the needs of intense ultrashort LWIR pulses, it is proposed to develop a LWIR OPCPA source driven by MIR Er:ZBLAN fiber lasers. This dissertation presents a numerical evaluation of GaSe and orientation-patterned GaAs performances in a nanosecond OPCPA, following a theoretical description of three-wave parametric interactions. The construction and performance of a nanosecond surrogate pump, based on optical parametric oscillation and amplification in KTiOAsO4 crystals, is then reported. It operates at a central wavelength of 2.73 μm and produces >10 mJ pulses of ∼1 ns pulse duration at a repetition rate of 10 Hz. The surrogate pump source not only enables the experimental evaluation of the OPCPA architecture but also supports the initial assessment of large-core Er:ZBLAN fiber amplifiers. The LWIR seed pulses generated via direct difference-frequency generation in an AgGaS2 crystal are centered at 10.3 μm with 1.1-μm bandwidth. The nanosecond GaSe OPCPA is further analyzed numerically in a noncollinear geometry, followed by the design and construction of a small-scale noncollinear GaSe OPCPA using the custom-built surrogate pump and seed sources for proof-of-concept studies. A design of nanosecond-long stretcher and compressor is also included, and the construction of a prototype that accommodates the current LWIR seed source with limited bandwidth is discussed. Although the broadband gain is still under testing, a preliminary study of small-signal gain in GaSe has been completed by using a narrow-band CO2 laser as the seed. Single-shot spectrometers and an autocorrelator have also been developed for characterization in the LWIR range. The development of the prototype paves the way to the first demonstration of a MIR pumped LWIR OPCPA. The prototype is aimed to reach the peak power comparable to what has been demonstrated in the MIR range to date and could be scaled to a high peak and average power in the future by pump technologies such as high-energy, coherently-combined MIR fiber laser.PHDNuclear Engineering & Radiological SciencesUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/169714/1/xuanxiao_1.pd

Nature and origin of secondary mineral coatings on volcanic rocks of the Black Mountain, Stonewall Mountain, and Kane Springs Wash volcanic centers, southern, Nevada

The following subject areas are covered: (1) genetic, spectral, and LANDSAT Thematic Mapper imagery relationship between desert varnish and tertiary volcanic host rocks, southern Nevada; (2) reconnaissance geologic mapping of the Kane Springs Wash Volcanic Center, Lincoln County, Nevada, using multispectral thermal infrared imagery; (3) interregional comparisons of desert varnish; and (4) airborne scanner (GERIS) imagery of the Kane Springs Wash Volcanic Center, Lincoln County, Nevada

A numerical framework for multiple phase cloud microphysics in regional and global atmospheric models

2012/2013The Regional Climate Model RegCM4 (Giorgi et al., 2012) treats nonconvective clouds and precipitation following the Subgrid Explicit SUBEX param- eterization (Pal et al., 2000). This scheme includes a simple representation for the formation of raindrops and solves diagnostically the precipitation: rain forms when the cloud water content exceeds the autoconversion threshold, that is an increasing function of the temperature and assumes different values over the land and over the ocean to account for the difference in number of the cloud condensation nuclei over continental and oceanic regions. The SUBEX scheme does not account for the presence of clouds ice, and the fraction of ice is diagnosed as a function of temperature in the radiation scheme. Due to the increasing emphasis on cloud representations in the climate community and the forthcoming increasing resolution due to the inclusion, in the close future, of a non-hydrostatic compressible core, the treatment of the ice microphysics and a prognostic representation of the precipitation is required in RegCM4. This thesis presents the new parameterization for stratiform cloud microphysics and precipitation implemented in RegCM4. The approach of the new parameterization is based on an implicit numerical framework recently developed and implemented into the ECMWF operational forecasting model (Tiedtke, 1993). The new parameterization solves 5 prognostic equations for the water vapour, the liquid water, the rain, the ice and the snow mixing ratios. It allows a proper treatment of mixed-phase clouds and a more physically realistic representation of the precipitation as it is no more an instantaneous response to the microphysical processes occurring in clouds and is subjected to the horizontal advection. A first discussion of the results contains an evaluation of the vertical distributions of the main microphysical quantities, such as the liquid and ice water mixing ratios and the relative fractions. It also presents a series of sensitivity tests to understand how the moisture and radiation quantities respond to the variation of the microphysical parameters used in the scheme, such as the fall speeds of the falling categories, the autoconversion scheme and the evaporation coefficient. Cloud properties are afterwards evaluated through the implementation for RegCM4 of the new cloud evaluation COSP tool (Bodas-Salcedo et al., 2011), developed by the Cloud Feedback Model In- tercomparison Project (CFMIP), that facilitates the comparison of simulated clouds with observations from passive and active remote sensing by diagnosing from model outputs the quantities that would be observed from satellites if they were flying above an atmosphere similar to that predicted by the model. Different hypothesis are presented to explain the reasons for RegCM4 biases in representing different types of clouds over the tropical band and new prospectives for the future investigations designed to answer to the open questions are outlined.XXVI Ciclo198