UCAR Communications

 

staff notes monthly

October 2003

An overview of projects throughout the organization

United Parcel Service (UPS) aircraft will soon carry something very special for UCAR—and it’s not packages. Instead, it’s an instrument to measure atmospheric water vapor. Rex Fleming (JOSS) has been working on the second-generation Water Vapor Sensing System (WVSS-II), an air sampler and laser measurement system that provides highly accurate data and is currently used on NOAA research aircraft. In August, UPS agreed to carry the instrument on 30 of its B-757 aircraft as part of a demonstration study and final certification test funded by the FAA and the National Weather Service.

The second-generation Water Vapor Sensing System accurately measured atmosphericwater vapor during this year’s BAMEX experiment.

The air sampler is mounted on the skin of commercial jet aircraft. It brings air into a small measurement cell inside the plane, where a laser then determines water vapor measurements.
Because commercial planes take off and land many times a day, they have the potential to provide detailed profiles of wind, temperature, and water vapor across space and time. These measurements are more accurate than conventional balloon-borne radiosondes that are launched twice a day around the world.

The WVSS-II was tested this year, both during the Bow Echo and MCV (Mesoscale Convective Vortex) Experiment (better known as BAMEX) and on scientific flights that collected data on Hurricane Isabel. After final certification, it will become part of a national commercial aircraft system.

The Digital Library for Earth System Education (DLESE) has released version 2.0 of its online library. The updated version has three important new features. In addition to searching for information appropriate to different grade levels, users (including teachers and other faculty members) can now search for information and lesson plans that support national science and geography education standards. They can also search within discreet collections from institutions like NASA and UCAR’s COMET program. And a new peer review system on the site lets users post comments about particular resources.

The DLESE team, headed by Mary Marlino, will continue to screen the abundance of Earth System resources on the Web to bring users only high-quality, useful information, along with teaching and learning tools. In a few years, staffers expect to release a third version that allows for geospatial searching.

Users can access DLESE at www.dlese.org.

CGD researchers are beginning to incorporate a dynamic vegetation model into the Community Climate System Model. This will enable them to peer back thousands of years, exploring how climate affected land cover and, in turn, how land cover influenced climate.

In a trial run, CGD’s Sam Levis simulated conditions in north Africa 6,000 years ago, when the now-arid region was comparatively fertile because of intense monsoons. He found that a greener north Africa, which had darker and more loamy soils than the sands of today’s Sahara Desert, helped fuel the monsoons for two reasons. The vegetation and darker soil absorbed sunlight (increasing ambient heat and providing more energy for the storms), and the soil collected a considerable amount of moisture (leading to local evaporation and providing potential storms with water vapor). These results suggest the importance of simulatingsoil characteristics, in addition to simulating vegetation.

Researchers next may look farther into the past, studying such issues as the extent of tundra during glaciated periods and the amount of sunlight it reflected back into the atmosphere. Although the dynamic vegetation model can also operate under present or future scenarios, its main use for the time being may be to research eras before humans affectedland cover.

Qian Wu (HAO) traveled to Resolute Bay in the Canadian high Arctic this summer, where he deployed a new Fabry-Perot interferometer at a polar cap observatory. His trip was part of a project that will address questions in mesospheric and thermospheric physics in support of the Coupling, Energetics and Dynamics of Atmospheric Regions (CEDAR) program.

Kim Streander, Greg Card, Ron Lull, Alice Lecinski, David Elmore, and Clarke Chambellan in the HAO Instrument Group developed the interferometer, with contributions from colleagues Stan Solomon and Dan Gablehouse and collaborators at Scientific Solutions, Inc. Specifically designed for routine observations of thermospheric and mesospheric winds and temperatures, Fabry-Perot interferometers consist of two parallel glass plates. The inner surfaces of the plates have a reflective coating and form a cavity in which light is reflected back and forth. The interference between these multiple reflections creates a pattern that scientists can ultimately use to measure windsand temperatures.

Along with other instruments already in placeat the polar observatory, the interferometer will contribute to our knowledge of the upper atmosphere. Data from the project will be available to the atmospheric science community through theCEDAR database.

A team of HAO scientists is building a prototype of a new instrument, called a coronal multichannel polarimeter, to learn more about the Sun’s coronal loops. The loops, a product of the Sun’s magnetic fields, are arch-shaped structures in the corona that constrain solar plasma. Motions of the underlying turbulent plasma can affect magnetic fields in the corona, causing the loops to come under stress and ultimately break apart. That causes a coronal mass ejection—a dramatic emission of charged solar particles that can buffet Earth’s upper atmosphere and affect orbiting satellites and communication systems.

Scientists previously have observed the underlying plasma, but the multichannel polarimeter would enable them for the first time to examine magnetic fields in the actual corona. This would provide insights into the forces that cause the loops to break down. The instrument includes a tunable filter (to filter out nonessential wavelengths) and an infrared camera.The instrument will focus on light emitted by atoms of Fe XIII (iron that has been ionized 12 times), which is a common and easily visible solar element.

The team, which includes Steve Tomczyk, Joan Burkepile, Greg Card, Roberto Casini, Tony Darnell, David Elmore, and Phil Judge, hopes to set up the prototype at a coronagraph at the National Solar Observatory in New Mexico as early as this month to gather preliminary data about coronal loops. If the research is successful, the scientists may pursue a grant to build a permanent instrument that can be mounted at HAO’s Mauna Loa Solar Observatory in Hawaii.

A coronal mass ejection in 1986. This composite view uses images from ground-based telescopes at HAO’s Mauna Loa Solar Observatory in Hawaii and from a coronagraph aboard NASA’s orbiting Solar Maximum Mission satellite.


Also in this issue...

WRF tags Isabel

Up close with Isabel

An online overhaul

A new hat for Bob Gall

Shuttle service provides transportation—and conversation

A look back

Short takes

Unidata wins funding for new forecasting tools

Delphi Questions

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