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ATD Achievements - Field Programs Select From: HVAMS AIRSII TELEX WISP-04 Ocean Waves Sierra Rotors NAME ACME OHATS

ATD exemplifies NCAR’s community service function. ATD’s activities advance the community’s observational capabilities through the deployment of existing facilities and the development, sometimes over many years, of new instrumentation and platforms. Two thirds of all ATD support activities serve university users and most involve users from several universities. Many university and NCAR scientists regard ATD’s capabilities and services as the primary justification for a national center. In FY04, ATD participated in 12 Field Projects throughout North America utilizing 12 of our facilities as well as the C-130.

FY 04 Field Programs

Hudson Valley Ambient Meteorology Experiment (HVAMS) (top)

Nine ISFF stations and TAOS were deployed in New York’s Hudson Valley from 15 September through 31October 2004 between Albany and Kingston, NY. David Fitzjarrald from SUNY, Albany, designed this study to examine how local topography and land use patterns affect boundary layer dynamics under predominantly fair weather conditions. During the intensive observation period of HVAMS, a fine-scale network of turbulence observations, enhanced remote sensing capability and aircraft measurements was used to study the physical mechanisms responsible for surface-atmosphere exchanges in this 500 km valley that stretches from New York City to the Canadian border. The nine ISFF were located at sites featuring different land use types and local exposure conditions to capture heterogeneities in radiative and surface fluxes, and to describe the evolution and structure of the nocturnal boundary layer and effects of land-surface heterogeneity on transport and dispersion. TAOS was used to assess environmental stability, moisture, temperature and winds in the lowest 300 m of the atmosphere and to analyze the development, decay and horizontal extent of the NLLJ. The Wyoming King Air provided flux measurements.

Alliance Icing Research Study II (AIRS II) and the Atlantic-THORPEX Regional Campaign (ATReC) (top)

Dr John Hallett of the Desert Research Institute and several co-investigators requested the use of the NSF C-130 with SABL in support of the Alliance Icing Research Study II (AIRS-II) field program. This was the second phase of a multi-agency, multi-platform project designed to investigate the current capabilities for remote sensing of aircraft icing. C-130 flight operations were conducted out of Cleveland Ohio and closely coordinated with other research assets. Its primary function was to characterize the cloud-active aerosol content of the upwind source region of a target area located near Montreal, Canada. AIRS-II was endorsed by the Aircraft Icing Research Alliance (AIRA), which consists of government organizations within North America interested in aircraft icing. It was also supported by the WMO World Weather Research Program project on Aircraft In-Flight Icing. ATD flew 81 research flight hours during the project.

ATReC was a joint effort of Atlantic THORPEX regional study and the Aircraft Icing Research Study II (AIRS II). The University of North Dakota Citation supported the project with coordinated flight tracks in conjunction with the NASA ER-2. The Citation’s primary mission was to provide Dropsonde data in real time to support project goals. These dropsonde data were placed on the Global Telecommunications System for inclusion into model runs, from the aircraft immediately after completion of a drop.

Thunderstorm Electrification and Lightning Experiment (TELEX) (top)

For a second year in a row, instrumented balloons were launched into storms during the Thunderstorm Electrification and Lightning Experiment (TELEX), which took place from May to June 2004 in Oklahoma. The broad objective of this two-year program is to understand how lightning and other electrical storm properties are dependent on storm structure, updrafts, and precipitation. The 2004 study aimed at testing and revising hypotheses concerning the inter-relationship among the wind field, microphysical characteristics, electrical structure, and lightning of isolated severe storms and of large storm systems. Balloon soundings launched from a NSSL mobile van were used to measure the electric field profile of storms. Dropsondes used as upsondes were flown along with an electric field meter on the same balloon to acquire vertical soundings of electric fields, winds and thermodynamic parameters.

WISP-04 (top)

The objective of this project, which took place at the Marshall Radar Site, was to develop techniques for detecting super cooled liquid droplets in single and mixed phase clouds. The project was funded by FAA and a number of NSF, NOAA and NASA observational facilities were used in the project. S-Pol radar with a new Ka-band radar system, GPS on mobile GLASS, NOAA Ka-band radar systems, a number of ground-based radiometers, video disdrometer, and Citation research aircraft from University of North Dakota were all used for observing clouds and precipitation along the front range.

Ocean Waves (top)

Dr Ken Melville of Scripps and Dr Carl Friehe of U.C. Irvine received funding from NSF for use of NSF C-130 in support of the Ocean Waves I program. Data were collected to study the coupling between the marine atmospheric boundary layer and the marine oceanic boundary layer through the surface wave field. Special attention was paid to the effects of wave breaking on air-sea fluxes and boundary layer development. Flight operations were conducted from Huatulco, Mexico with flight legs targeting air-sea interactions over the eastern Pacific Ocean where the wintertime flow regime immediately off the coast was characterized by strong gap flow winds that originate in the Gulf of Mexico and transit through the mountain passes.

A variety of optical sensors including SABL was be used to measure the surface wave field. In situ measurements of various surface fluxes, meteorological and chemical, and profiles of the thermal structure in the upper mixed layer of the ocean were used to study the coupled development of the surface wave field and the air-sea boundary layer in off-shore wind conditions. The GPS Dropsonde system documented the environment of the marine atmospheric BL to within a few meters of the surface.

Sierra Rotors (top)

The Sierra Rotors Project was an NSF-funded project to study mountain-wave induced rotors in the lee of the Sierra Nevada in Owens Valley. Rotors are intense horizontal vortices with strong turbulence that can pose severe aeronautical hazards. The eastern slopes of the southern Sierra Nevada make up the tallest, steepest, quasi-linear topographic barrier in the contiguous United States, and are well-known for generating large-amplitude mountain waves and strong rotors over the Owens Valley. The main objective of this project was to establish quantitative characteristics of the rotor behavior as well as to evaluate the extent to which current operational mesoscale models can reliably forecast the occurrence of rotors. NCAR/ATD deployed a mobile Integrated Sounding Systems (MISS) and a fixed ISS with MAPR near Independence as well as a mobile GLASS system near Fresno, CA. Sierra Rotors served as the pilot study for the Terrain-induced Rotor Experiment (T-REX), scheduled for spring 2006.

For more information, see the section on Community Research: Remote Sensing of Terrain-Induced Waves and Rotors on our Research Achievements page.

NAME (top)

The North American Monsoon Experiment (NAME) was an internationally coordinated, multi-agency project that investigated the sources of warm season precipitation over North America. The project focused on observing and understanding the key components of the North American monsoon system and variability within the context of the evolving land surface-atmosphere-ocean annual cycle. Richard Johnson from CSU was funded to deploy three Integrated Sounding Systems (ISS) and one GPS/Loran Atmospheric Sounding System (GLASS) on the east and west side of the Gulf of California. Steve Rutledge was the main PI for NCAR’s S-Pol radar, which was temporarily located about one hour north of Mazatlan to observe and describe the daily cycle of convective rainfall, the structure and location of precipitation systems, and to characterize the microphysics. To support the high frequency soundings component of NAME, ATD temporarily hired 15 US and 2 Mexican students for the duration of the project, providing a substantial educational component to the project.

Airborne Carbon in the Mountains Experiment (ACME) (top)

The C-130 and three ISFF were deployed by NCAR/ATD in support of the Airborne Carbon in the Mountains Experiment (ACME) in summer 2004. Dr David Schimel (NCAR - MMM) was funded by NSF (Biocomplexity) and collaborated with CU, CSU, U. Miami, and NCAR ATD, and CGD to combine airborne data with ground-based measurements to obtain a more accurate picture of carbon exchange over complex terrain on regional scales. Results from the field program will also be used in testing computer models of forest ecosystem function. These models could potentially help in accurately assessing to what extent carbon dioxide storage in Western mountain forests--a potentially important "sink" for the greenhouse gas--may be slowing down as the ongoing drought and wild fires affects tree growth.

The C-130 operated from its home base at Jefferson County Airport in Colorado and airborne measurements focused on carbon dioxide, moisture fluxes, carbon monoxide and fast ozone. ATD flew a total of 54 hours on the NCAR C-130 aircraft over large regions of the Colorado Rocky Mountains, making continuous measurements of CO2, CO, O3, and water vapor concentrations, and collecting discrete flask samples for 13C and 18O isotope ratios in CO2 (University of Utah). In addition to these primary measurements, ATD also flew the MCR scanning radiometer with thermal and vegetation channels (Tschudi), collected flask samples for radiocarbon measurements and for verification of our in situ CO2 and CO measurements (Scripps Institution of Oceanography), and collected high rate CO2, CO, O3, and water vapor data for direct eddy-correlation flux estimates (Campos).

The flights were conducted according to a combination of experimental designs, including morning to afternoon Lagrangian flux measurements, regional survey measurements for assimilation into a high-resolution ecosystem-atmosphere model, morning sampling of nocturnally respired CO2 and its concentration by topography and dispersion by turbulence, flask sampling to resolve elevation gradients in isotope signatures, and direct flux measurements. Our analyses of these data are just beginning, but preliminary results are encouraging. During the Lagrangian experiments and regional surveys, ATD observed CO2 drawdowns of several ppm in boundary-layer CO2, representing significant CO2 uptake by the forests and strong signals for use in our analyses. Also, in large mountain valleys ATD observed on the order of 30 ppm of respired CO2 pooling as deep as 1000 ft. and persisting until 10 AM, which may suggest techniques for making respiration estimates on relatively large scales. Our results are already helping the community adapt plans for the North American Carbon Program to improve constraints on mountain carbon fluxes. Our airborne measurements will be compared to and integrated with the extensive ongoing carbon and ecosystem measurements at Niwot Ridge and an enhanced network of ground-based measurements deployed as part of the broader Carbon in the Mountains Experiment (CME).

To enhance the existing carbon-cycle measurements at this site, ATD deployed three ISFF towers which continuously monitored temperature, humidity, 3-dimensional winds, CO2 fluxes, and high-accuracy CO2 concentrations at multiple levels up to 30 m in the Como Creek watershed on Niwot Ridge near Nederland, CO. Twelve prototype low-level Adaptive Sensor Array (ASA) sites were deployed to characterize soil respiration. The figure above left shows the installation of the ground sensors. In response to results from a pilot experiment in 2002, ATD's Hydra instrument was deployed to sample CO2 concentrations at 12 locations along a 260m transect that crossed the local drainage between the University of Colorado's Ameriflux tower and one of the ISFF towers.The CO2 concentration instruments included the HYDRA system with 18 inlets and three new AIRCOA units with six inlets each. These observations will be used to fully resolve the atmospheric transport of CO2 in order to accurately measure the net ecosystem carbon exchange, and as input to a regional-scale data-assimilation model to improve our understanding of the processes controlling carbon cycling by mountain forests.

Ocean Horizontal Array Turbulence Study (OHATS) (top)

Dr Peter Sullivan (NCAR/MMM) and colleagues from Woods Hole Oceanographic Institute (WHOI) and Penn State University requested the use of ISFF sonic anemometers in summer 2004 for the Ocean Horizontal Array Turbulence Study (OHATS). OHATS is part of an ongoing effort to investigate wind-wave interactions and their impacts on weather forecasts and climate variability.

An array of 18 sonic anemometers was deployed on the Air-Sea Interaction Tower (ASIT), a 12-meter platform that is located off the coast of Martha's Vineyard. The sonic anemometers were suspended below the tower in two arrays of 9 sonics each at about 5 and 5.5 meters above mean sea level. Other measurements, provided by WHOI and ingested by the ISFF data system, include an independent CSAT3 sonic at a height of 9 m, collocated with a Licor 7500 fast water vapor and CO_2 sensor and a Vaisala hygrothermometer; three laser wave height sensors; and an inertial motion package attached to the crosswind array. The PIs studied the physical processes that generate and/or modulate the turbulent transfer of momentum, heat, and mass through the atmospheric surface layer to the underlying surface, especially how wind-generated waves and swell influence the marine surface layer and air-sea fluxes. The ultimate goal of the research is to improve how these wave-induced processes are simulated in numerical models. Data collection from these arrays began in early August 2004 and ended in early October 2004, which allowed collection of data that captured a wide range of conditions.

INTEX-NA Field Study (NASA Deployment) (top)

The modified TDLAS system was deployed this past summer during the NASA-funded 2004 INTEX-NA field campaign to study North American pollution outflow and chemical transformations. The system improvements worked extremely well in all respects, and this allowed us to successfully acquire ambient CH2O measurements on 19 out of the 20 mission flights. Preliminary field data have been submitted and ATD is in the process of preparing finalized data to NASA.

Table of Contents | Director's Message | Executive Summary | ATD Achievements
Education and Outreach | Community Service | Awards | Publications | People | ASR 2004 Home