Xinzhao Chu - US grants

The investigators will study middle atmosphere composition, structure and dynamics using sodium lidar measurements. There are two parts to the proposed effort: 1) analysis and interpretation of the wind, temperature, and sodium density data obtained at the Starfire Optical Range in New Mexico between 1998 and 2000, and 2) the study of thermal tides and gravity wave momentum, heat, and constituent transport using observations made by a sodium lidar at the Maui Space Surveillance Site (MSSS) beginning in January 2000. The Starfire data will be used to characterize the seasonal variations in wave activity and momentum, heat, and constituent fluxes in the mesopause region at a mid-latitude continental site. A similar set of observations will also be collected at the Maui facility, a low-latitude, mid-ocean site. These observations are made feasible by using the 3.7-meter steerable telescope at Maui as the lidar receiver. Both nighttime and daytime observations will be conducted to study tidal perturbation of winds and temperature and to study gravity wave transport processes and their seasonal variations. The low-latitude tide and flux observations will be compared to similar mid latitude data from previous measurements made at Starfire and Urbana, Illinois. The study will contribute to knowledge about gravity wave dynamics in the middle atmosphere with application to studies of global change.

Two data streams, Fe-Boltzmann lidar temperature data and balloon sounding data are used to characterize the Antarctic atmosphere from 0 - 110 km. The research goals are to develop thermal climatology in the Antarctic during the next three years, to investigate Polar Mesospheric Cloud climatology relative to known Arctic conditions, and to investigate gravity wave behavior in the Antarctic mesosphere. Inter-comparisons of data from Rothera Antarctica (67.5o S) are compared with and integrated with other Antarctic stations and with the TIMED satellite to develop a global description of the polar mesosphere for model constraint. The lidar and balloon programs are logistically and financially supported through an international collaboration with the British Antarctic Survey.

Observational research with a Na wind and temperature lidar, currently located at the Maui Space Surveillance Complex (a USAF facility) on Mt. Haleakala, HI, is continued. The 3.7 m aperture lidar is the centerpiece of a suite of optical and radar instrumentation located nearby for the purpose of collaborative studies of dynamics in the mesosphere and lower thermosphere (MALT). The research focus is three-fold. The first task quantifies the gravity wave induced vertical flux of horizontal momentum including directional information relevant to ducting. The directional aspect of gravity waves is used to help determine the location of generating sources. The second task is quantification of gravity wave phase and velocity using both optical and radar measurement techniques, to detect and compare both high frequency and low frequency wave phase and wave speed. The third task is to study and quantify gravity wave induced heat and constituent fluxes in the MALT region.

Measurements of daytime temperature near the mesopause are accomplished using an upgraded Potassium (K) lidar at the Arecibo Observatory. The diurnal mean temperature structure at and just below the mesopause is determined by full twenty-four measurements, and the dominant tidal modes present at Arecibo are also determined. Gravity wave spectra in mesospheric metal layers are determined in the three variables of temperature, wind, and density. These parameters are extracted from simultaneous ISR measurements of winds and ISR spectral shape, while the K-lidar provides measurements of temperature and the resonant K emission strength. The chemistry of metallic layers in the mesosphere is investigated in the context of the full diurnal layering morphology.

Four middle and upper atmosphere lidar groups collaborate to unify the scientific and technological applications of resonant lidar systems now at the University of Illinois, the Alomar Observatory in Norway, and at Colorado State University. The consortium structure coordinates simultaneous performance of the lidar systems and the sharing of existing data, coordinates data taking strategic planning within the upper atmospheric lidar community, facilitates more rapid dissemination of technical lidar advances, and coordinates education, training, and outreach activities. The consortium establishes a Technology Center that focuses on unified establishment of robust and stable lidar operation, the exploration of advanced laser and optical technologies, and the expedition of technology transfer within traditionally isolated and competing lidar groups. The initial goal of the consortium is to make regular nighttime and daytime measurements of temperatures and winds in the upper mesosphere and lower thermosphere commonplace and consistent at the three primary lidar sites.

The investigators will develop an advanced, mobile, iron-resonance/Rayleigh/Mie Doppler lidar system to vertically profile temperatures, winds, meteoric iron densities, clouds and aerosols throughout the stratosphere, mesosphere and lower thermosphere. The proposed lidar integrates the state-of-the-art technologies of lasers, laser spectroscopy, electro-optics, and sensors into a single system to produce a powerful and robust tool with unmatched measurement capabilities. The revolutionary lidar design and the readiness of alexandrite laser technology make the Fe Doppler lidar superb in the following ways: it will be able to obtain simultaneous measurements of temperature (30-110 km), wind (80-110 km), Fe density (75-115 km), and aerosol (10-100 km) in both day and night with high accuracy, high precision, and high spatial and temporal resolutions. The lidar is robust and compact for groundbased mobile deployment. It is containerized to move via a truck or ship to field locations of interest with extensive geographic coverage. Chirp-free and dither-free frequency locking and saturation-free Fe layer resonance results in a bias-free estimate of winds and temperatures, which is revolutionary for Doppler lidar. High energy and the UV wavelength employed by the lidar leads to a much more sensitive estimate of temperature and aerosol backscatter in stratosphere and mesosphere than determined through Na and K lidars. The 80-cm multi-telescope receiver, double-etalon filter for high rejection of solar background, and a state-of-the-art diagnostic system ensures accurate measurements in both day and night. The resulting breakthrough in lidar technology will push the atmospheric observations to a completely new level and the mobility of the system will enable new scientific endeavors. The lidar will become a community tool, available to all scientific users. Partnerships with private sector companies will result in new products with wide scientific use and commercial impact. Innovative technologies developed in this project will lead to new applications of advanced laser and remote sensing technology in the detection of biological and chemical agents, in nano-scale tube engineering, and in semi-conductor inspection. Exceptional opportunities for graduate and undergraduate education and training will arise from this project. A large number of scientists have strong interests in the instrument development, spin-off applications, and the data collected by this lidar. Many of these scientists will educate and train graduate and undergraduate students for whom this instrument and its data will be essential. Minority and under-represented students will be recruited through the Woman in Engineering Office (WIE) and Research Experience for Undergraduates (REU). This project will support the research of a female scientist (PI).

This is a CAREER award that will set a solid foundation for a young scientist in developing a successful academic career through creative and exciting research, education, and integrated activities. The focus of the work plan is to advance research and education in lidar remote sensing and the applications of global lidar data to middle and upper atmospheric science. The research represents the first time that worldwide lidar data will be combined to create a global picture of the thermal structure of the mesosphere and lower thermosphere (MLT) via the use of satellite data and computer simulations. These efforts will significantly advance our understanding of the global MLT thermal structure and will further our knowledge of middle atmosphere dynamics that govern these variations. This research will also test and improve sophisticated global circulation models through use of these observational data. Because this project will identify altitudes in the MLT region where the temperatures undergo minimum seasonal variations, it will be important for establishing a temperature baseline that can be used to monitor climate change. This project will significantly advance our knowledge of the least understood region of the atmosphere, which is the equatorial and transition region of the middle atmosphere. This project will also significantly increase the usage of the lidar data collected at Arecibo Observatory, a national facility for scientific research, and at other sites around the world. Through analyzing past and present data, the large data backlog will be reduced, and scientific results will be obtained to help guide future data collection and instrumentation upgrades. The study will act as a bridge to encourage collaborations between modelers and experimentalists to dramatically increase the use of lidar data in testing and improving GCM models. This project provides excellent opportunities to educate and train graduate and undergraduate students, and to advance the integration of atmospheric science with lidar engineering. Students will gain extensive knowledge and experience through classroom learning of lidar remote sensing and then applying them to active lidar research. This project will help the principal investigator to successfully develop her academic career. The activities align well with the PI's career goals of establishing a strong lidar and atmospheric research and education group at the University of Colorado, and developing a center of excellence for lidar technologies and applications for the middle and upper atmosphere community.

This one-year project aims to complete construction of a daytime potassium Doppler lidar and to test its operation at Arecibo Observatory. The Arecibo lidar, based on a narrowband injection-seeded alexandrite ring laser, has been able to make nighttime temperature and potassium density measurements in the mesosphere and lower thermosphere region since February 2001. Through seven years of operation, the nighttime technology has matured and sufficient data were collected to characterize the nocturnal thermal structure and nocturnal potassium seasonal variations. To enhance its measurement capability and to better serve the aeronomy community, in 2005 a project was proposed and received funding for three years to upgrade the Arecibo lidar to a daytime observing capability and to conduct extensive observations to study the tropical mesosphere and lower thermosphere region over the full-diurnal cycle at the Arecibo Observatory. The lidar modifications have been underway for the past three years but the Faraday filter originally intended to be used did not perform as expected. Many of the other technical goals of the previous project were achieved, such as narrowing of the field-of-view, construction of the Faraday filter test station, implementation of the new receiver optical chopper, initial observational tests, and implementation of new data processing techniques. In addition, the optical elements and hardware necessary to construct a new Faraday filter were acquired. The project will therefore complete the remaining steps to yield a daylight-optimized lidar capable of making full diurnal observations at Arecibo, where its collocation with the incoherent scatter radar will enable a wide variety of scientific studies, such as measurements of tides, gravity waves, absolute atmospheric density, metal layer chemistry, and the evolution of sporadic atom and ion layers.

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5). The project is to deploy a field-proven Fe Boltzmann temperature lidar to the U.S. Antarctic station McMurdo, and to conduct there multi-year observations pursuing the following scientific objectives: (a) To establish a temperature record throughout the polar atmosphere at 78°S to monitor climate change, (b) To validate sophisticated atmospheric models that are used to project the future state of our climate system, and (c) To characterize the thermal structure, polar mesospheric clouds, heterogeneous chemistry, large-scale dynamics, and gravity waves in the polar middle atmosphere. The project's long-term goal is to operate the lidar at McMurdo through complete 11-yrs solar activity cycle characterizing middle atmosphere responses to the solar activity and its annual and inter-annual variations, and extracting long-term secular trends to assess potential climate changes in the middle atmosphere. These observations will provide crucial information on the polar middle atmosphere in the critical latitudinal gap region mid-way between the South Pole and Antarctic Circle, completing observations in combination with previous measurements made at the South Pole and Rothera stations. Analysis of the atmospheric gravity wave fields at McMurdo will be particularly useful in advancing understanding of wave coupling and providing better constraints to wave parameterizations by utilizing simultaneous lidar, MF radar, and satellite measurements.

This project is to develop and deploy new lidar technology that would enable simultaneous observation of wind and temperature in the troposphere, stratosphere, and mesosphere. Specifically, a sodium double-edge magneto-optical filter will be designed and integrated into the receiver of an existing sodium Doppler lidar. This effort will extend current narrow-band resonance wind-temperature lidar capabilities, which are based on scattering by atomic constituents in the mesosphere, by accommodating scattering by aerosols and molecules at lower altitudes. The new measurements of wind and temperature, extending from the ground to 50 km and from 80-105 km, will facilitate improved understanding of the structure and dynamical coupling between the lower and middle atmosphere.

This is a 5-year scientific collaboration to investigate vertical transport mechanisms in the upper mesosphere and lower thermosphere (MLT) using a combination of theory, observations, and atmospheric chemical models. The study focuses on the mesopause region, 80-105 km altitude, and employs Na and Fe wind/temperature lidar, meteor radar, and airglow data from two observation sites at Cerro Pachon, Chile, and Table Mountain, CO. The objectives are to quantify wave-induced vertical transport in the mesopause region above these sites, to characterize its effects on the fluxes and vertical distribution of heat, Na, Fe, O, and other key constituents, and to compare the measurements to the eddy diffusion parameterization schemes that are traditionally used to account for vertical transport in atmospheric chemistry models. Specific scientific goals include:
1) To characterize the vertical fluxes of heat, Na (at Cerro Pachon) and Fe (at Table Mountain) throughout the mesopause region and throughout the year,
2) To determine the effective vertical constituent transport velocities associated with advection, turbulent mixing, dynamical transport and Na/Fe chemistry and to characterize their seasonal variations,
3) To quantify the influence of wave-induced transport on the structure and seasonal variations of the mesospheric Na and Fe layers by comparing model predictions with observations,
4) To characterize the effective vertical transport associated with OH Meinel Band, O(1S) green line and O2 Atmospheric Band airglow emissions throughout the year at Cerro Pachon, and
5) Through model calculations to assess the influence of wave-induced transport on the structure and variations of other important mesospheric constituents such as atomic O.

Intellectual Merit: Knowledge of the magnitude and variability of wave-induced vertical transport is important to a wide range of research problems, including general circulation modeling, atmospheric chemistry modeling, thermal balance calculations, and the study of the mesospheric airglow and metal layers. This work will contribute to a much deeper understanding of the key gravity wave transport processes and their relationships to atmospheric chemistry. In addition, this work will significantly enhance our ability to model the constituent structure of the MLT, particularly the meteoric metal and airglow layers.

Broader Impacts: The research has broader implications for atmospheric science because the results can be used to characterize the impact of wave-induced transport on other important constituents in other atmospheric regions, such as stratospheric ozone, which in turn affects the thermal balance of the Earth's atmosphere. Hence, the results of this project may have important applications in global climate modeling. Furthermore, the direct measurements of the vertical fluxes of mesospheric Fe and Na, in combination with modeling, will substantially improve current estimates of the absolute value of the global meteoric input flux, which are highly uncertain. This is important because the meteoric debris that enters the MLT is eventually transported into the lower atmosphere, where it affects the formation of stratospheric aerosols and is ultimately deposited in the oceans, where it contributes to the concentration of key chemical species, such as Fe. Both stratospheric aerosols and oceanic Fe play important roles in Earth's climate. Stratospheric aerosols reflect sunlight, which alters the Earth's radiation budget, while oceanic Fe promotes the growth of phytoplankton, which affects the global carbon cycles, in particular atmospheric CO2.

The new observations of iron layers, neutral temperatures, and gravity waves up to 155-km altitudes with the Fe-Boltzmann lidar (deployed at McMurdo in 2010) have opened a new door to explore the Antarctic neutral thermosphere. These measurements of neutral-ion coupling and Joule heating, in the critical region above 100 km, are an objective of highest priority for the upper atmosphere science community. Development of the neutral atmosphere temperature climatology is crucial for calibrating satellite observations of the polar mesosphere-lower thermosphere (MLT) region and validating global climate models; in decades from now this climatology records will serve as the baseline against which long-term temperature trends in the changing Antarctic climate are assessed. The studies of extreme summertime Fe events and solar effects on Fe-layer's bottom side are improving the understanding of iron chemistry at polar latitudes. The vertical heat and constituent flux observations with the lidars are enhancing the knowledge of wave-induced transport in the polar mesopause region and remove the greatest source of uncertainty in current chemical-dynamical models of the mesospheric metal layers. This also led to improvements in quantitative estimates of the cosmic dust input that has implications for a variety of geophysical processes throughout the Antarctic atmosphere and Southern Ocean. The characterization and analysis of the gravity wave field in the neutral atmosphere above McMurdo are advancing the understanding of wave coupling in the MLT region and provide better constraints on wave parameterization schemes in climate models. Thus, the McMurdo lidar campaigns provide a new look into the composition, chemistry, temperature, and dynamics of the polar upper atmosphere in a critical latitudinal gap region mid-way between the South Pole and Antarctic Circle. The Fe-Boltzmann lidar has already produced a rich dataset stored in the CEDAR/Madrigal database, which is readily available to other scientists to help supporting their own research on polar aeronomy and climate. This project provides exceptional opportunities to train students and young researchers by giving them fieldwork experience in Antarctica. The project also enhances classroom teaching and graduate programs at several prominent universities around the world.

The goal of this project is to investigate wave forcings originating from the lower atmosphere including their sources, wave interactions and coupling, and their impacts on ionospheric/thermospheric variability. Meteorological sources of wave energy from the lower atmosphere are responsible for producing significant variability in the upper atmosphere, which impacts space weather. Vertical wave coupling is a fundamental atmospheric process that has profound effects on the variability of the ionosphere and thermosphere.
This project will utilize existing and ongoing lidar and Incoherent Scatter Radar (ISR) observations to collectively study atmospheric waves in both the neutral atmosphere and ionosphere, and the Whole Atmosphere Model (WAM) to understand and interpret these rich datasets. In particular, the project will focus on characterizing 1-9 h period gravity waves by comparing observations with simulations in terms of magnitude, vertical and horizontal wavelengths, propagation direction, and latitudinal distribution. The tidal modulation of fast gravity waves will also be studied, and the source regions identified.

Two Doppler lidars, a newly developed iron (Fe) Doppler lidar and an existing sodium (Na) Doppler lidar will be operated simultaneously at Table Mountain near Boulder, CO, to acquire vertical profiles of neutral atmospheric horizontal and vertical winds, temperatures, and Fe and Na densities in the mesosphere and thermosphere to study coupling and transport processes between 80 and 150 km. The thermospheric metal layers themselves involve the coupling between ion and neutral metal layers, and the neutral winds and temperatures derived from these layers are two critical parameters needed for advancing our understanding of the space-atmosphere interaction region. The neutral wind and temperature data in the mesosphere and thermosphere will help validate global models that cover the lower and upper atmosphere (e.g., WACCM and WAM). The simultaneous measurements of Fe and Na layers and their fluxes will provide crucial information on the thermospheric metal layer formation, differential meteoric ablation, and cosmic dust velocity distribution. This work will lead to improvements in quantitative estimates of the cosmic dust input that has implications for a variety of geophysical processes throughout the polar atmosphere and Southern Ocean.
Specifically, the dual lidar observations, along with correlative studies and model simulations, will be used to: (1) Characterize the recently discovered thermosphere Fe and Na layers above Table Mountain to determine how frequently they occur, how high they extend, how long they persist, and what mechanisms cause them to form; (2) Characterize neutral winds and temperatures in the 100-150 km region of the thermosphere by using the thermosphere Fe and Na layers as tracers. Explore coupling and transport processes via comparison with the Whole Atmosphere Model (WAM) simulations; and (3) Make simultaneous measurements of wave-induced vertical heat fluxes and the dynamical and chemical fluxes of Fe and Na in the mesopause region (80-105 km) to quantify the differential meteoric ablation of Fe and Na, constrain the various cosmic dust velocity distribution models, help validate the University of Leeds chemical ablation model (CABMOD) and significantly improve estimates of the global influx of cosmic dust. This project will provide research opportunities for a postdoc and a graduate student.

This proposal is to deploy a sodium lidar at McMurdo, Antarctica, in addition to the previously installed Fe-Boltzmann lidar also funded by NSF. Like radars, the LIDARs (LIght Detection And Ranging) are the devices that can examine various properties of the upper atmosphere from a large distance and at various altitudes. From a single location, these devices can scan the environments and observe polar atmosphere and ionosphere at the 80-200 km altitude within a wide sector covering thousands of square miles. They monitor an atmospheric chemical composition, temperature and other features, analyze atmospheric gravity waves, and measure vertical winds and interaction between plasma and neutral winds. The lidars also can study features and irregularities of various layers of the atmosphere, and monitor their dynamics.

Many scientists are already using the data of the previously installed instrument, and the new lidar will bring another kind of measurements of airglow with high temporal and spatial resolution. Simultaneous monitoring of many atmospheric parameters enriches our understanding of atmospheric dynamics in general and gravity waves, mixing, and vertical transport in the studied region. By fully characterizing vertical constituent transport in the mesopause region caused by gravity waves and turbulence, as well as determining the differential ablation of Na and Fe, will substantially reduce the large uncertainties in current estimates of cosmic dust influx into the Earth's atmosphere. Accurate observation of these essential parameters will provide important data sets of polar atmosphere conditions and dynamics and allow obtaining new crucial information for many scientists and many areas, including weather studies, atmospheric and ionospheric studies, and others. This research effort will continue to develop the NSF-funded instrumentation network to help addressing fundamental questions of the Geospace research that have not yet thoroughly examined.

This is a project that is jointly funded by the National Science Foundation?s Directorate of Geosciences (NSF/GEO) and the National Environment Research Council (NERC) of the United Kingdom (UK) via the NSF/GEO-NERC Lead Agency Agreement. This Agreement allows a single joint US/UK proposal to be submitted and peer-reviewed by the Agency whose investigator has the largest proportion of the budget. Upon successful joint determination of an award, each Agency funds the proportion of the budget and the investigators associated with its own investigators and component of the work. The WAVECHASM project seeks to improve models of the atmosphere by including small scale processes from the upper atmosphere into a large scale model housed at the NSF's National Center for Atmospheric Research. This cross disciplinary project brings together the physics of the near Earth space environment and atmospheric chemistry.

Wave-induced transport in the atmosphere is important to a wide range of research problems, including general circulation modelling, atmospheric chemistry modelling and thermal balance calculations. However, computational cost constraints mean that it has not so far been practical to include small-scale wave transport effects directly in global models. WAVECHASM will enhance understanding of wave transport processes and their relationships to chemistry by improving our ability to model the constituent structure of the mesosphere and lower thermosphere (MLT, 70-120 km). The objectives are to quantify constituent transport theoretically, to develop a wave-transport parameterization scheme suitable for incorporating into existing global atmospheric chemistry models, and to use the upgraded models to characterize wave-transport effects on the morphologies of key MLT constituents. The US participants are responsible for developing the wave parameterization scheme and testing its efficacy using extensive observational data collected by numerous (unfunded) project partners from around the globe. The UK participants are responsible for incorporating the parameterization scheme in the NCAR Whole Atmosphere Community Climate Model and for assessing its performance against a high-resolution regionally refined version of WACCM. Both the US and UK participants with then use the upgraded models to quantify the wave- and turbulence-induced vertical fluxes of key MLT species (Na, Fe, OX, HOX, COX and NOX) and determine their relationships to wave sources in the troposphere and stratosphere.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

This award is funded in whole or part under the American Rescue Plan Act of 2021 (Public Law 117-2).

The Geospace coupling system consists of multiple domains transferring solar wind energy and momentum through the Earth's magnetosphere down to the polar ionosphere and thermosphere (neutral upper atmosphere). The 100-200 km altitude region is one of the most important domains where the magnetospheric energy dissipates by precipitating charged particles and respective Joule heating of the upper atmosphere. However, this plasma-neutral coupling in this domain is the lees understood one because it is located well below satellite-observing altitudes, so only remote sensing techniques from the Earth's surface are available here - and observations of neutral winds and temperatures in this range of altitudes are rare. The observations that have been acquired by the LIDAR instrumentation at the McMurdo Station in Antarctica over the last decade have already enabled compelling new science. Studies of plasma-neutral coupling significantly advanced understanding of these complex space-atmosphere interactions.

This award will advance a new concept of multistep vertical wave coupling from ground to the thermosphere that was develop from discoveries made by McMurdo lidars. This concept helps advancing the space weather modeling by better assessing the impact of the lower atmosphere forcing on the ionosphere and thermosphere dynamics. Gravity wave forcing on the polar upper atmosphere via wave drag and mixing is important to a wide range of research problems, including general circulation modeling, atmospheric chemistry modeling, thermal balance calculations, studies of airglow and metal layers, and the estimates of the cosmic dust influx. The development of the absolute temperature climatology is crucial for calibrating satellite observations of the polar thermosphere and its connections with the mesosphere and lower atmosphere – they are needed to validate global climate models, and decades from now will serve as the baseline against which long-term temperature trends in the changing Antarctic climate are assessed. The sodium and Fe-Boltzmann lidars that have been operated at McMurdo acquire vertical profiles of neutral atmospheric parameters, including temperature from 30 to ~200 km, vertical winds, and iron & sodium densities in the mesosphere and lower thermosphere region. This will provide answers on new science questions related to the complex physics, chemistry, and dynamics of the polar atmosphere and Geospace that are inspired by McMurdo lidar discoveries. These studies provided unique opportunities to train a new generation of scientists and engineers.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.