The WiFE test program was conducted on the C-130 during six weeks in September and October of 1998 (spanning FY98/99). The program was intended to access the viability of various remote sensing devices in the study of wildfire behavior in complex terrain. The aircraft traveled to wildfire sites throughout the intermountain west and California. The instrumentation package included a digital thermal camera, a US Forest Service spectral radiometer, remote surface temperature sensors and the full suite of RAF state parameters to record 3-D wind fields and humidity profiles. NCAR's microwave scanning device AIMR was used to estimate the amount of biomass surrounding the fires and also directly measured brightness temperatures while passing over the fires. Additional measurements of certain key chemical species, such as the CO/CO2 ratio and NMHC's provided information on combustion efficiencies.

The principal investigators were Larry Radke (NCAR/ATD) and Terry Clark (NCAR/MMM). The resulting data set is being used to help test and refine the performance of Clark's computer simulations of wildfire behavior. The WiFE test program was supported by staff from RAF under the leadership of Project Manager Allan Schanot.

Leonid Mission '98

In anticipation of a major meteor storm, caused by comet 55p/Temple-Tuttle's return to the inner solar system on its path around the Sun, NASA scientists requested the two aircraft and equipped them with a multitude of instruments. The goal was to observe the debris and dust particles that collide with the Earth's atmosphere often producing spectacular fireballs and shooting stars, and to study the physics and chemistry of meteor accretion into the Earth's atmosphere.

The instrumentation installed on the Electra included Chester Gardner's (University of Illinois Urbana-Champaign) Fe-Boltzman lidar system, Gary Swenson's (University of Illinois Urbana-Champaign) air-glow imager, Peter Jenniskens' (NASA Ames Research Center) low light level video cameras and a low light level high resolution video camera from NHK, the Japanese Public Television company. The Fe-Boltzman lidar was used to map the vertical distribution of iron deposited by the vaporizing meteors between 80 and 100 kilometers. The video images are used to count and classify the meteors, comparing meteor brightness with iron density and temperature measured by the Fe lidar. The all-sky airglow imager, which has a fisheye lens, provided a view of the whole sky, recording the number of meteor trails during the shower. A telescope spectrograph from the University of East Anglia, UK, measured the spectra of the meteor trails to determine their relative compositions. And an infrared spectrograph from the University of California at San Francisco was used to detect the presence of carbon compounds that may have played a role in the development of primitive life on the Earth billions of years ago.

Although 1998 failed to display the expected once-in-a-lifetime meteor storm, the Leonids 98 program was a full success. The night of the mission was clear and the visible meteor rates reached a peak of approximately 300 meteors/hour between 4 and 5 am local time (in comparison, a meteor storm could display between 200,000 and 400,000 meteors per hour). The NASA Leonids web site contains a nice collection of early data and pictures and more information on the project.

The Leonids mission was supported by staff from RAF and DFS under the leadership of Project Manager Bruce Morley.

Images courtesy of various members of the Leonids 98 Science Team.

Tropical Rainfall Measuring Mission (TRMM) Brazil

In November 1998, NCAR's S-Pol radar was shipped to Ji-Parana, Rondonia in west-central Brazil. Steve Rutledge from Colorado State University and several of his colleagues had obtained funding from NSF and NASA to support the Tropical Rainfall Measuring Mission

TRMM Brazil observation focused on dynamical, microphysical, electrical and diabatic heating characteristics of tropical convection in Amazonia. The project was conducted in parallel with the wet season component of the Large Scale Biosphere-Atmosphere Experiment in Amazonia (LBA), an international research initiative to understand the climatological, ecological, biogeochemical, and hydrological role of the Amazon region in the overall Earth system and the effects of land use on regional and global weather patterns.

The project had a rough start and experienced significant logistical hurdles before all major components eventually arrived in Brazil by mid-January. To make up for some of the delay, S-Pol was flown on a USAF C-5 aircraft from San Antonio,TX to Brasilia, Brazil and from there transported on muddy roads to its site on deforested pasture land about one hour outside of Ji-Parana. Staff from RSF, DFS, and SSSF set up the radar in record time. S-Pol and the TOGA radar formed a dual-Doppler network which provided detailed views of the precipitation structure and the three-dimensional wind field of often huge mesoscale convective systems that appeared in the afternoon and often lasted until deep into the night.

S-Pol performed extremely well and ran for approximately six weeks, 24-hours per day, registering only one single 24-hour down period in mid-January. The project managers for TRMM were Bob Rilling, Jothiram Vivekanandan and Jim Wilsom. RSF, RDP and DFS staff probably won't remember the project for cloud tops and reflectivities, but for its exotic insects, the occasional snake, Brazil's heavy traffic, its friendly people, the mahagony outhouse, and for Bart's fishing story.

Images courtesy of Chris Burghart, Scott Ellis and Mike Strong, all ATD.

Indian Ocean Experiment (INDOEX)

From early February through March 1999, NCAR's C-130 was a major player in the

INDOEX was based in the Republic of the Maldives, an archipelago southwest of India's southern tip. The C-130 and the main operations center were based at Male International Airport, which consists of one runway and occupies its own island in the archipelago. An ATD GLASS was located at the Kaashidhoo Observatory, on a small, bean-shaped island, 3 km by 1 km large, about 85 km south of Male. In addition to the NCAR facilities, the project was supported by three other airplanes (the Dutch Citation, the German Falcon, and the French Mystere), two research vessels (R/V Ronald Brown and R/V Sagar Kanya), several surface and sounding stations spread across several islands, and a wide range of satellites.

The main objective of the experiment was to assess the impact of air pollution originating from Asia and the Indian subcontinent and surrounding nations on climate processes over the tropical Indian Ocean. Aerosols make up a large part of the pollution and scatter incoming solar radiation, reducing the amount of sunlight that reaches the ocean surface and thus reducing the amount of solar energy that would otherwise heat the earth-atmosphere system. The process is known as global cooling. Aerosols are also an important source of nuclei around which cloud droplets can condense. The more cloud condensation nuclei, the brighter the cloud, that is the more solar radiation is reflected back into space before it reaches the earth's surface.

Within a couple of days, preliminary measurements indicated that these air pollutants dramatically impact the northern Indian ocean region, producing a dense brownish haze and decreasing visibility over the open ocean to under 10 km. In contrast, the lower atmosphere over the southern Indian Ocean seemed remarkably clean. The InterTropical Convergence Zone (ITCZ), a narrow zone of deep and towering thunderstorms that form over the warmest part of the equatorial ocean, intercepts these polluted air masses and removes much of the pollution in rainfall. However, the ITCZ clouds can also move substantial amounts of pollutants into the upper atmosphere where they can be spread over large areas, contributing to air pollution world-wide.

The INDOEX mission was supported by staff from RAF, RSF, SSSF, and DFS under the leadership of Project Managers Dick Friesen, Krista Laursen, Allan Schanot, Bruce Morely and Craig Walther.

Coupled Forest Atmospheric Boundary Layer Experiment 1999

For a second year in a row, ATD/SSSF supported the Regional Forest-Atmospheric Boundary Layer project for Ken Davis from the University of Minnesota. The project, which will continue in FY2000, is an observational study of the coupling between terrestrial ecosystems and the atmospheric boundary layer (ABL) and focuses on the dynamics that influence CO2 profiles, the exchange of CO2 between the ABL and the free troposphere and the coupling between the ABL and forest physiology.

Direct measurements of the exchange of CO2 between terrestrial ecosystems and the atmosphere are extremely useful for understanding the mechanism which control terrestrial carbon uptake. This uptake has been underestimated because of inadequate representation of the coupling between ecosystem metabolism and turbulent mixing in the ABL. Photosynthesis, ABL turbulence and atmospheric convection over land are all forced by solar radiation at the surface and they are therefore strongly correlated in nature, with strong ventilation and deeper mixing of CO2-depleted air during the day and the growing season and systematic retention of CO2-enriched air under the nocturnal inversion and during the transition season. This produces a "rectifier effect" which results in a vertical gradient of several parts per million in the annual mean CO2 concentration over land. This effect is strongest over the temperate and boreal latitudes of the northern hemisphere, where vegetation and ABL turbulence are most strongly correlated on seasonal time scales and where the land area is greatest, and therefore produces a north-south gradient in annual mean CO2 concentration.

The first phase of the Forest Atmospheric Boundary Layer (ABL) experiment took place during the 1998 growing season (March through October) at the WLEF TV tower in Park Falls, Wisconsin. The TV tower has been instrumented to make continuous eddy-covariance measurements of CO2, H2O and heat fluxes at three levels (30, 122, & 396 m). During the 1998 experiment ATD/SSSF provided an Integrated Sounding System (ISS) to measure the boundary layer height to aid in determining CO2 mixing ratios in the ABL. This year (1999) SSSF provided two ISS. While one ISS was again installed at the WLEF TV tower site, the other ISS was installed at the Walker Branch flux tower site in Oak Ridge Tennessee. The goal, again this year, was the study of the net ecosystem exchange of CO2 ; specifically to test this rectifier effect, to clarify the role ABL dynamics play in modulating atmospheric indicators of ecosystem metabolism, and to measure atmospheric CO2 profiles in a contrasting ecosystem to northern Wisconsin (Oak Ridge Tennessee). A second goal was to try and adapt the methods developed at the WLEF tall tower, where flux divergence observations and high altitude CO2 data are available, to a lower surface-layer flux tower or series of towers. There are approximately 80 long-term CO2 flux towers running or are being constructed around the world, so the transfer of the methods developed at Park Falls would have global applications.

The NCAR facilities provided continuous and highly resolved views of winds, turbulence, temperature and cloud content of the BL and intermittent measurements of humidity profiles spanning both diurnal and season time scales.

The project was carried out by SSSF staff and overseen by project engineer Mike Susedik.

Numerical Simulation of Weather Modification by Cloud Seeding

This project was part of a larger NASA-funded program called the Upper Missouri River Basin (UMRB) project that emphasizes coupled hydrologic modeling of Intermediate Scale Areas (ISA) in orographic terrain, the use of observations of differing temporal and spatial resolutions to assess ambient variability as well as model and budget uncertainties and sensitivities, intercomparison of sensors and the transferability of models from the Black Hills ISA to other ISAs.

The project involved staff from SSSF and DFS and was overseen by project engineer Ned Chamberlain.

Soil Moisture / Sea Salinity Project - TAS Test

NAURU 99

The campaign was conducted on and in the vicinity of Nauru, a small island in the western tropical Pacific ocean northeast of Australia and Papua New Guinea (see map).

Data were obtained from instruments installed at the Atmospheric Radiation Cloud (ARC) site on Nauru, the Japanese research vessel Mirai, the NOAA research vessel Ron Brown, and the TAO buoy array. Additional data were obtained from the Flinders University Cessna aircraft and satellite.

SSSF deployed a range of instruments for a month on board the Mirai. These included MAPR, a DBS wind profiler with RASS, surface meteorological instruments, a sea snake temperature probe, and a microwave water vapor radiometer (belonging to Radiometrics Inc), as well as operating an S-Band radar for NOAA. RSF staff operated the High Resolution Doppler Lidar (HRDL) on board the Ron Brown. All instruments performed well and analysis of the observations is continuing. Aspects being studied include the diurnal cycle of the tropical boundary layer, convection, island heating, and bulk fluxes. The deployment of MAPR was noteworthy, being the first time a spaced antenna profiler has been operated at sea. It made unique high resolution observations of tropical squalls and observed not only rain but also strong up-drafts and circulations suggestive of gravity waves around the squalls.

Nauru99 was sponsored by the US Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) program, NOAA, and the Japanese Marine Science and Technology Center (JAMSTEC). In addition to SSSF, RSF and DFS personnel, staff from the Brookhaven National Laboratory, various NOAA laboratories, Penn State University, the Australian Bureau of Meteorology, the German Max Planck Institute, Hamburg and the Samoan Le Vai Moana Marine Center participated in Nauru99.

Study of Electrical Evolution in Thunderstorms (SEET)

Thomas Marshall from the University of Mississippi requested GPS dropsonde support for the SEET project from 20 July to 10 August 1999. The main goal was to measure the evolution of principal charge regions inside small thunderstorms that occurred over central New Mexico.

In order to meet his needs, SSSF modified their GPS dropsondes to be used in a balloon-borne, "up-sonde" mode of operation, tracking four sondes simultaneously to permit multiple, simultaneous, electric field soundings. Three to six sondes were launched into each thunderstorm with individual launches separated by 5 to 10 minutes. Each balloon carried an electric field meter to provide electric field data and the dropsonde to provide position data and thermodynamic sounding throughout the cloud. To meet positioning requirement, an OEM code-correlating GPS receiver was replaced by the standard codeless GPS receivers, i.e., full GPS position calculations happened with in the sonde itself rather than in the ground- or air-based receiver system. An air flow scoop was also added to the sonde for ventilation of the temperature and relative humidity sensors.

A total of 30 soundings were made and the "upsonde GPS dropsondes" performance was excellence not just meeting but exceeding data and accuracy requirements as well as quality control aspects of data compilation. For the first time precise locations of charge regions inside thunderstorms were measured and the scientific data exceeded all other thunderstorm electric field measurements collected so far.

The lead engineers for the development of the GPS dropsondes are Terry Hock and Dean Lauritsen.

Transitions

From 20 June to 17 July 1999, ATD/SSSF supported Amanda Lynch from the Cooperative Institute for Research in Environmental Sciences and her colleagues to study the spatial and temporal transition of climate and ecosystems in the circumpolar Arctic.

The Arctic plays a crucial role in global change because it is a sensitive indicator of change and stores short and longterm climatic records. The Arctic also affects the global climate directly through interactions between its atmosphere, ice cover, land surface and ocean, and through strong feedback processes. Practically all climate models predict an amplification of the global greenhouse effect at high northern latitudes, but models as well as observations have produced results that are not easily interpreted.

The driving hypothesis in Transitions was that the surface energy and moisture exchange between the atmosphere, ecosystem, snow, permafrost, and soil is the principal mechanism for coupling the land surface to the climate on seasonal to decadel time scales. A better understanding of the characteristics, mechanisms and feedback processes of this exchange is necessary to incorporate their effects into pan-Arctic climate models. Particular regions of interest are the transition regions of Arctic climate and ecosystems e.g., the polar front and boreal forest treeline, which have surface energy budget and atmospheric boundary layer characteristics that are not well understood. These transition regions are likely to have a profound affect on the alteration of ecosystems, permafrost, snow and atmospheric circulation distributions under a changing climate.

One of the critical parameters for permafrost-land-atmosphere coupling was the characterization of the the boundary layer growth and dynamics. ATD/SSSF therefore installed the ISS in the ATLAS study area near Council, Alaska on the Seward Peninsula. Upper-air soundings were made during several Intensive Observing Periods to verify the ISS radar wind profiler measurement of boundary layer height and for measuring moisture profiles. The soundings made at Council will be compared to the nearest National Weather Service sounding site at Nome, which is about 75 miles away.

Transitions was part of the ATLAS (Arctic Transitions in the Land-Atmosphere System) project, which is housed within the Land Atmosphere Ice Interaction (LAII) program of the overall Arctic System Science (ARCSS) program.

The project involved staff from SSSF and DFS and was overseen by project engineer Mike Susedik.

Arctic Mesoscale Temperature Study (AMTS)

In June and July 1999, NCAR once again supported Chet Gardner and George Papen from the University of Illinois during the Arctic Mesoscale Temperature Study (AMTS). Their Fe Boltzman lidar, which was jointly developed with ATD/RAF and Aerospace Corporation, was installed on the NCAR Electra and flown to the Arctic. The goal was to make the first measurements ever of the temperature structure in the coldest region of the Earth's atmosphere.

Atmospheric models predict mesospheric temperatures below 130 K near the North pole at 90 km altitude around the summer solstice. By comparison, measured winter temperatures at mid-latitudes at similar altitudes are more than 100 K warmer. Since the temperature structure at the highest latitudes is neither well documented nor fully understood, global circulation models of the middle atmosphere in the polar regions are unreliable. Furthermore, there are no instruments situated in the Arctic that are capable of routine temperature observations during summer.

The Electra deployed to Resolute Bay, Nunavut, Canada in mid-June 1999 and made four flights from there to the North Pole during late June and early July. In addition to measuring these high latitude temperatures and their perturbations, engineering data on the lidar, Fe densities, and daytime background noise levels were acquired, which are crucial to planning future airborne and ground-based deployment scenarios for this new lidar.

The project was supported by staff from RAF and DFS under the leadership of Project Manager Bruce Morley.

Pictures courtesy of Chet Gardner, University of Illinois.

Mesoscale Alpine Project (MAP)

Every year in fall, the

MAP pulled together a large array of observational platforms: The S-Pol radar was temporarily sited on a landfill at Vergiate in the Lago Maggiore region. The radar was used to study the intense weather events over Northern Italy caused by Mediterranean moisture being pushed against the Alps. Precipitation products were sent from the radar site to the MAP Operations Center in Innsbruck and the Project Operations Center at the Milano-Linate airport. Additional radars from France, Switzerland and Italy as well as the Doppler on Wheels from the University of Oklahoma joined forces with S-Pol and complemented the radar data set.

The NCAR Electra was equipped with the ELDORA radar, GPS dropsondes and SABL, which was used to find gravity waves over the Alps. The Electra joined a fleet of seven other aircraft and operated out of Innsbruck, Austria.

Additional measurements were made by a network of wind profilers, lidars, sounding systems, automated weather stations and rain gauges located all over the Alpine regions.

There were two major foci for the U.S. component of the MAP Program: (1) Wet MAP - Orographically generated heavy precipitation events, with special emphasis on dynamics, microphysics and hydrological consequences; and (2) Dry MAP - terrain-induced airflow phenomena, with emphasis on upper-level gravity wave breaking, potential wave breaking, potential vorticity generation, generation and gap flow through the mountain passes.

Coordinated Electra and P-3 missions were flown on numerous Wet and Dry MAP cases providing excellent geophysical coverage on specific events and opportunities for validating ground radar measurements with aircraft in-situ cloud physics measurements. Scientific directors for MAP were Philippe Bougeault (Météo-France) and Ron Smith (Yale University) for the first and second halves of MAP, respectively. Bob Houze (University of Washington) was overseeing the Wet-MAP component from Linate. The MAP project was supported by staff from RAF, RSF, SSSF, RDP and DFS under the leadership of project managers Allan Schanot, Krista Laursen, Dick Friesen, Wen-Chau Lee, Tammy Weckwerth, Jothiram Vivekanandan and Jim Wilson.