Ben Balsley - US grants

The objective of this research is the deployment and operation of three stratospheric.tropospheric (ST) radars in the tropical Pacific to make new measurements of convection, atmospheric waves, and turbulence. The radars will be constructed using components of the larger MST radar originally constructed at Poker Flat, Alaska. Additionally, three boundary layer profilers, recently developed by the Aeronomy Laboratory, will be deployed to measure the field of motion from the surface to near 10,000 feet.

This proposal concerns an initial attempt to establish a relationship between climatic variations due to El Nino and growth patterns of one or more long-lived trees found in the desert along the north Peruvian coast. Preliminary results, already in hand, indicate that some trees in this region-specifically the Sapote (Capparis Angulata R. & P.)-live for at least a few hundred years, and perhaps much longer. Although the task of determining a chronology of tree growth in the tropical desert is formidable, it appears that at least a crude chronology is possible by comparing the average growth pattern obtained from a series of transverse sections and cores from separate Sapotes with radiocarbon dating of selected Sapote samples. A concomitant study to establish ongoing growth patterns and their relationship to local climate variations will augment our current understanding of Sapote, and will add considerable insight into our research efforts. The establishment of a proxy chronology of El Nino variability over the past few centuries, particularly in the El Nino sensitive region along the north Peruvian coast, is of considerable value in our search to understand this enigmatic but economically critical phenomenon.

The objective of this research is the demonstration of the practical validity of measuring electric potential in the atmosphere using several kites attached to a common tether. If this technique is successful, a simple and relatively inexpensive method will be available to monitor continuously electric potential and, by inference, that of the earth.ionosphere system. The measurements will be conducted on Christmas Island, Republic of Kiribati.

This project is an effort to construct, install and operate a monostotic Very High Frequency (VHF) wind profiling radar at the Peruvian Antarctic Base on King George Island in the Antarctic Peninsula. Similar wind profilers have operated successfully in other remote areas in the western equatorial Pacific, and in equivalent polar latitudes in Alaska. The system will provide nearly continuous measurement of the total wind vector through the troposphere and lower stratosphere, and is capable of expansion to make observations of the horizontal wind in the region from 70 km to 100 km altitude. The project will be carried out cooperatively with the Peruvian Antarctic program.

The objective of this research is the investigation of the field of motion in the tropical Pacific using four existing VHF (50 MHz) radars located in Peru, Christmas Island, Phonpei, and Biak, Indonesia. Topics for investigation include measured vertical motion, the vertical flux of horizontal momentum between the boundary layer and roughly 20 km. These measurements will be used in cognate studies of gravity waves, thermal convection and tidal oscillations. This research is a joint activity between the University of Colorado and NOAA's Aeronomy Laboratory.

9411761 Balsley In this project the researchers plan to extend the capabilities of state-of-the-art kite technology for atmospheric sampling and related research. The workplan will accomplish this feasibility experiment by (1) increasing the current maximum attainable height from around 3 km to over 13-14 km, and by (2) using the tethered kite as a "sky hook" to enable a small device (a "WindTRAM") to travel up and down the kite tether to obtain high- resolution profiles of ozone, temperature, pressure, and humidity. If successful, the project results will be a unique and inexpensive technique to study vertical profiles of critical atmospheric species throughout the entire troposphere and possibly the lower stratosphere.

Abstract 9319068 Fritts This project will measure the dynamics of the mesosphere and lower thermosphere (MLT) at high time and spatial resolution (2 minutes and 2 kilometers) using two medium frequency (MF) radars. The first radar will be built near McMurdo and the second either at Palmer Station or, if it is logistically more convenient, at the nearby Peruvian station on King George Island. These instruments will allow detailed studies of large and small scale motion fields and their latitudinal and temporal variability. When the data are compared to similar products from Northern Hemisphere radars it will be possible to study inter-hemispheric differences in the behavior of the MLT, which preliminary studies indicate are quite substantial. ***

9401750 Balsley The objective of this proposal is to provide Jicamarca Observatory users with the capability for making extended, long- term measurements of the lower atmosphere, the equatorial electrojet, spread F, and the 150 km echo at 13 dB reduced sensitivity. The PIs propose to add two new receivers, a pair of low-power (no-cost) transmitters, and an independent low-cost analysis system. ***

Balsley/Abstract The purpose of this activity is to obtain vertical distributions of both temperature and moisture near the coast of Peru (at 4 degrees South) using radiosondes equipped with Vaisala sensors. The larger meteorological purpose is to caputrue the thermodynamic structure of the atmosphere during the initial stages of an El Nino especially in a region where such measurements have never been made.

As part of the CASES-99 program (Cooperative Atmosphere-Surface Exchange Study-1999), the PI will measure the temperature, pressure, humidity, and wind velocity with high resolution in time and altitude using instruments suspended from a tethered kite or, in calm conditions, a tethered blimp. The purpose of CASES is to study the physics and dynamics of the very stable nocturnal boundary using an array of surface-based instruments, remote sensing observations, a 60-m instrumented tower, and two instrumented airplanes. Observations by the kite/blimp system will provide vertical profiles up to about 2 km, supplementing the aircraft measurements and filling the important altitude gap between the top of the tower and the minimum aircraft altitude. It will also provide time series of temperature and wind velocity at selected altitudes to permit the observation of transient events such as intermittent bursts of turbulence, strong gusts, and wave motions. Phenomena of special interest are low-level jets, wave instabilities, and the turbulent mixing of air across the nocturnal inversion. These measurements, in combination with simultaneous observations by the instrumented tower, the aircraft, and the remote sensing equipment (radars, lidars, wind profilers) will constitute an excellent set of data for studying the dynamics of the stable boundary layer throughout its entire vertical extent.

A continuing series of grants since 1988 has made it possible for CIRES of the University of Colorado, in collaboration with the NOAA Aeronomy Laboratory, to construct, operate, and maintain VHF wind-profiling radars at four sites stretching across the equatorial Pacific: Biak, Indonesia; Pohnpei, Micronesia; Christmas Island, Kiribati; and Piura, Peru. Observations from the profiler at Christmas Island are now assimilated into operational forecast models on a routine basis. Ongoing research activities based on data from the network include: (1) documentation of seasonal and interannual variability of winds over the Tropical Pacific; (2) investigation of the structure of atmospheric Kelvin waves, Rossby waves, and gravity waves; (3) measurement of the vertical structure and amount of rainfall at the profiler sites; (4) obtaining data for the validation of atmospheric models. The network fills both research and operational needs for data on winds and precipitation in the Tropical Pacific - a region important for the global climate, but where other sources of data are scarce.

As part of the CASES-99 program (Cooperative Atmosphere-Surface Exchange Study-1999), the PI measured the temperature, pressure, humidity, and wind velocity with high resolution in time and altitude using instruments suspended from a tethered kite or, in calm conditions, a tethered blimp. Preliminary analysis of the data has revealed sharp temperature inversions, intermittent bursts of turbulence, and apparent wave phenomena, all with unprecedented resolution. This grant supports the continuing analysis of CASES-99 data. The analysis is focused on the following objectives:
(1) statistical characterization of the turbulence in selected homogeneous layers;
(2) investigation of turbulence in the vicinity of horizontal interfaces separating layers with different turbulence characteristics;
(3) study of turbulence intermittence, including calculation of spectra of the energy dissipation rate e and the temperature structure parameter Ct2;
(4) examination of the structure of Kelvin-Helmholtz instabilities and other wave phenomena in collaboration with large-eddy simulation modelers;
(5) entering other collaborations with CASES-99 researchers in the analysis of different data sets.

This research advances the fundamental understanding of atmospheric turbulence and enables improved parameterization of the diffusion and vertical transport of heat, momentum, and material in the nocturnal atmospheric boundary layer.

This research consists of three separate, but closely coupled objectives: The first objective is to analyze high-resolution vertical profiles of temperature, wind, and turbulence dissipation rate using the tethered lifting system (TLS) in conjunction with concurrent 55-m tower data and related data sets during CASES-99, a large cooperative experiment to observe boundary layer processes. The work will establish the capability of the TLS to extend some of the tower observations through the stable boundary layer (SBL) and well into the so-called residual layer (RL). To provide one important example, TLS profiles of the turbulence dissipation rate will be compared with tower-obtained vertical velocity variance profiles. If this comparison is successful under most nighttime conditions, it will enable a determination of the mixing height (MH) of the SBL, even though the MH lies well above tower heights. Comparable studies using other tower/TLS measurements will be conducted.

The second objective is to examine fine-scale wind speed, wind direction, temperature, and turbulence structure in the residual layer during over forty hours of observations obtained over five separate CASES-99 nights. The SBL structure during these periods ranged from traditional, through thin-traditional, and contained to at least one night when the SBL could be classified as upside down. It will be demonstrated that the RL does not fit the current view that it is a region of statically stable temperature profiles and minimal turbulence activity, and that it is merely a passive remnant of the previous day's convective boundary layer. Rather, it will be demonstrated that the RL is a very dynamic, complex region with significant wind shears, temperature gradients, turbulence structure, and, on occasion, pronounced gravity wave activity. More significantly, it will be shown that the vertical profiles of small-scale turbulence often exhibit extreme intensity variations (more than two orders of magnitude) over very small altitude ranges, and on time scales of a few tens of minutes. These enhanced turbulence regions, even after local midnight, can, on occasion, be comparable to nighttime levels at the surface, and could have a significant impact on vertical transport between the RL and SBL.

The third and ultimate objective is to incorporate the above concepts into current models of both the SBL and the RL in order to improve understanding of both upper level SBL dynamics and SBL/RL interactions. In this work, the focus will be on modeling the morning transition and how it is impacted by processes in the RL during the preceding night. Although it would be difficult to directly include some aspects of this research into single column models, the results should prove invaluable as a means of comparing model-derived quantities with measured quantities to be able to understand the importance of and sensitivity to the studied processes.

Intellectually, the above activities will provide critical new information for the theoretical/modeling communities on complex, dynamical processes throughout the SBL and well into the RL. On a broader scale, the anticipated results will provide valuable new insight into long-distant pollution transport in the RL and illuminate the as-yet unexplained, sporadic coupling between the two regions. Results from these efforts will provide a useful framework for designing future field campaigns. Finally, the post-doctoral candidate will learn to work in both modeling and observational research arenas, which is very important for future success in this field.

The Principal Investigator (PI) will study the evolution of the first few km of the lower atmosphere during the Terrain-Induced Rotor Experiment (T-REX). The T-REX is a multi-investigator focused on the study of mountain rotors and other lee wave phenomena. In his research, the PI will use state-of-the-art high-resolution Doppler lidar and high-resolution profiles of velocity, temperature, turbulence, ozone, and aerosol particle concentration. The PI also will deploy a Tethered Lifting System (TLS). The focus of this effort is the evolution of small-scale turbulence, wave-turbulence interactions, and variations of the boundary layer height and dynamics during the rotor events. In addition, new lidar algorithms will be modified to provide real-time profiles of turbulence and wind information to guide the deployment of field instruments, particularly aircraft and tethered systems, when conditions of high turbulence are present and pose a possible hazard.

The Doppler lidar analyses will focus on extracting reliable small-scale turbulence information by correcting the effects of the spatial averaging by the lidar pulse volume. This development will permit more accurate comparisons between the lidar results and the in situ turbulence measurements provided by the TLS profiles. Comparable developments in the TLS technique will enable concurrent, high-resolution profiling of winds, temperatures, and turbulent properties from the surface to heights of a few km. A newly developed temperature sensor chain flown from the TLS will also be deployed to provide more accurate temperature gradients for measurements of thermal stability in the boundary layer. The primary focus of the in situ measurements will be the stable boundary layer (SBL) and the nighttime remnants of the daytime convective processes that define the residual layer (RL). Daytime conditions will also be considered depending on the logistical constraints of the field program and the importance of the daytime measurements for the various stages of the rotor evolution.

The intellectual merit of the research includes an improved understanding of boundary layer processes from the unprecedented high-resolution in situ data and the three dimensional measurements of wind fields and turbulence with Doppler lidar. The simultaneous measurements will also provide the first validation of accurate turbulence estimates with an operational Doppler lidar as well as verification of new model derived estimates of small scale turbulence which are critical for next generation optimal data assimilation and numerical weather prediction models.

The broader impacts include improved methods for model parameterization especially correct calculations of the boundary layer height, improved forecasts of terrain induced turbulence for aviation safety, and new input to optimal data assimilation for the challenging conditions of complex terrain and stable boundary layers. The value of real-time wind speed and turbulence profiles will be demonstrated to guide future field campaigns.

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).

The Investigator will develop a simple, effective, and inexpensive method of obtaining very high-vertical-resolution atmospheric measurements made in close proximity to the SOUSY radar beam in Jicamarca Peru (a NSF Upper Atmospheric Facilities funded center). To make these measurements, the Principal Investigator (PI) will use a GPS-controlled mini-glider (Databird) that will be lifted to altitude using a meteorological balloon.

Following its release at altitude, the Databird will be programmed to glide to the radar beam coordinates and then descend in a tight spiral around the radar antenna to provide a high-resolution potential temperature profile virtually in line with the radar beam. These potential temperature profiles will be used in conjunction with radar obtained profiles of wind speed to produce profiles of the local gradient Richardson number (Ri). The resulting Ri profile will then be compared with concurrently-measured radar echo profiles to determine the relationship between the turbulence-related echo strengths and local dynamic instability criteria (Ri < 0.25). Results from this initial study have the potential to provide new insights into the important relationship between local dynamic instability profiles and turbulence echoes.

An additional important feature provided by the Databird measurements will be to obtain information on recently-discovered atmospheric "overturning" events. These events are visible in the potential temperature profiles and occur on vertical scales of tens to hundreds of meters. Overturnings appear to be a ubiquitous feature in both the troposphere and stratosphere, and probably extend to much higher altitudes. Using the glider system, the investigator will examine the (possibly) causal relationship between overturnings, critical Ri values, and turbulence generation.

The success of this effort will provide first-time high-resolution /vertical/ measurements of the entire lower atmosphere between 0 km and 10 km. Vertical resolution is important in this type of measurement, since most balloon borne data does not provide sufficient information for modelers and theoreticians because (1) the resolution is too poor and since (2) the balloon profiles are typically smeared along-track (wind-driven balloons can be tens of km downwind be the time they reach useful operating heights). Therefore, one can anticipate that the data will be used extensively to improve models and theory as the observing technique matures, and as observations are made at a variety of locations and under a variety of different atmospheric conditions.

The investigator is involving young foreign scientists in Peru in this project. Assuming that the initial tests are as successful, it is possible that larger-scale program involving U.S. graduate students could be initiated. Student participation could include all aspects of the glider design, including higher-height capabilities, field work, analysis techniques, comparisons of results with other types of data and models. Note that implementation of these ideas must await the success of the tests to be conducted with the Databird system.

This is a 3-year project to undertake experimental and theoretical studies of Kelvin-Helmholtz Instability (KHI) dynamics and their implications for turbulence and mixing in the Earth atmosphere. KHI is known to occur throughout the lower atmosphere as well as the mesosphere and lower thermosphere (MLT) and to contribute significantly to the dynamics. In addition, KHI evolution affects VHF Doppler radar wind measurement errors by producing strong, persistent layering and a systematic tilting of refractive index surfaces on scales comparable to VHF radar Bragg scales. This project addresses both of these aspects. Observations will be performed at the Jicamarca Radio Observatory (JRO) in Peru, which provides an exceptional combination of sensitivity and resolution throughout the lower atmosphere and the MLT. High range resolution and sensitivity at mid-tropospheric heights provided by the SOUSY Radar (at JRO), coupled with concurrent, quantitative, high-resolution, in situ measurements made using a newly developed unmanned aerial system, named the micro-autonomous vehicle (MAV), will provide an unsurpassed assessment of both high resolution KHI dynamics and radar measurement errors. The relatively high-resolution and higher-power capability provided by the powerful JRO transmitter and large antenna array will then extend the SOUSY results into the MLT. Finally, these observations will be used to initialize a series of numerical assessments of KHI radar backscatter and associated dynamical parameters using a new capability to perform direct numerical simulations (DNS) to characterize, and guide corrections of, measurement errors accompanying these dynamics for general flow conditions.

The inaccuracies in radar wind measurements from KHI is a limiting factor in understanding atmospheric dynamics on essentially all scales of motion, including: mean motions, wind shears, large-scale tidal and planetary wave activity, smaller-scale gravity wave dynamics, and small-scale instabilities and turbulence-generating processes. The results from this project, therefore, will improve practically all applications of VHF radar observations to great benefit of the scientific community as well as weather and climate modeling applications. The project also will result in improved quantitative understanding of interactions between waves and instability dynamics that drive motions throughout the atmosphere and at all scales. This will lead to better parameterization of small-scale dynamics in weather and climate models.