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Atmospheric Radiation Measurement Program Facilities Newsletter - June 1999.

Description: The Mesoscale Convective Systems (MCSs) Campaign is underway at the SGL CART site and will continue through September 1999. This field study is investigating the small-scale physics of precipitation and the convective dynamics of MCSs in the middle latitudes. An MCS is defined as a precipitation system that is 10--300 miles wide and contains deep convection at some time in its life span. MCSs occur in the midlatitudes of the US and can include large, isolated thunderstorms, squall lines, and mesoscale convective complexes.
Date: July 15, 1999
Creator: Holdridge, D. J., ed. & Sisterson, D. L.

Atmospheric Radiation Measurement Program facilities newsletter, June 2001.

Description: The ARM Program studies clouds, sunlight, and their interactions to understand how they affect Earth's climate. One of the many instruments used to look at clouds at the SGP CART site is the micropulse lidar (MPL; ''lidar'' was coined from ''light distance and ranging''). The ARM Program operates five MPLs. One is at the SGP central facility; one is at the North Slope of Alaska CART site in Barrow, Alaska; and three are for use at the Tropical Western Pacific site on Nauru and Manus islands. The MPL is a remote sensing instrument used to measure the height of overhead clouds and particles. An eye-safe laser in the system directs a beam vertically. As short pulses of laser light travel through the sky, they may encounter water droplets or aerosol particles in the atmosphere. These particles intercept the laser light and scatter it in different directions. Some of the scattered light returns to Earth's surface. A receiver on the ground collects backscattered light that bounces off atmospheric particles and uses the information to determine the distance between the ground and the particles. The signals detected are collected and plotted. The greater the signal strength, the more scatterers are present in the atmosphere. A plot based on this relationship provides a ''snapshot'' of the cloud overhead and shows the structure inside the cloud. In addition, the information gathered from the MPL can be used to determine the height of the planetary boundary layer, the well-mixed layer of the atmosphere that develops during daytime hours as the sun heats Earth's surface and sets up vertical mixing. Small airborne particles that can also be detected include smoke or dust carried into the atmosphere. This information is valuable to climate researchers. Because the MPL uses an eye-safe laser, it is not a danger to ...
Date: July 10, 2001
Creator: Holdridge, D.J.

Atmospheric radiation measurement program facilities newsletter, June 2002.

Description: ARM Intensive Operational Period Scheduled to Validate New NASA Satellite--Beginning in July, all three ARM sites (Southern Great Plains [SGP], North Slope of Alaska, and Tropical Western Pacific; Figure 1) will participate in the AIRS Validation IOP. This three-month intensive operational period (IOP) will validate data collected by the satellite-based Atmospheric Infrared Sounder (AIRS) recently launched into space. On May 4, the National Aeronautics and Space Administration (NASA) launched Aqua, the second spacecraft in the Earth Observing System (EOS) series. The EOS satellites monitor Earth systems including land surfaces, oceans, the atmosphere, and ice cover. The first EOS satellite, named Terra, was launched in December 1999. The second EOS satellite is named Aqua because its primary focus is understanding Earth's water cycle through observation of atmospheric moisture, clouds, temperature, ocean surface, precipitation, and soil moisture. One of the instruments aboard Aqua is the AIRS, built by the Jet Propulsion Laboratory, a NASA agency. The AIRS Validation IOP complements the ARM mission to improve understanding of the interactions of clouds and atmospheric moisture with solar radiation and their influence on weather and climate. In support of satellite validation IOP, ARM will launch dedicated radiosondes at all three ARM sites while the Aqua satellite with the AIRS instrument is orbiting overhead. These radiosonde launches will occur 45 minutes and 5 minutes before selected satellite overpasses. In addition, visiting scientists from the Jet Propulsion Laboratory will launch special radiosondes to measure ozone and humidity over the SGP site. All launches will generate ground-truth data to validate satellite data collected simultaneously. Data gathered daily by ARM meteorological and solar radiation instruments will complete the validation data sets. Data from Aqua-based instruments, including AIRS, will aid in weather forecasting, climate modeling, and greenhouse gas studies. These instruments will provide more accurate, detailed global observations of ...
Date: July 3, 2002
Creator: Holdridge, D. J.

Atmospheric radiation measurement program facilities newsletter, June 2003.

Description: The two article in this publication are (1) ARM Instrument Team Meets at SGP--Instrument team representatives from all three ARM CART sites (SGP, North Slope Alaska [NSA], and Tropical Western Pacific [TWP]) met at the SGP central facility during the week of June 9, 2003. The meeting agenda included an instrument-by instrument review of the operation and maintenance procedures used by instrument mentors and technicians, as well as refresher training for the technicians who maintain the instruments year-round. The group discussed new functions for ARM instrument mentors and the engineering and operations procedures for replacing instruments in the field or deploying new instruments. Attendees also viewed demonstrations of a new reporting system for data quality problems. (2) AERI Cross-Calibration Study Concludes--A brief study at the SGP central facility on June 6-11, 2003, compared two types of interferometers, instruments that measure the absolute spectral radiance of the sky and sky brightness temperature directly overhead. The measured data can be used to calculate vertical profiles of atmospheric temperature and relative humidity. The present ARM instrument, the atmospheric emitted radiance interferometer (AERI), was built by the University of Wisconsin. For comparison, researchers at the Department of Energy's Remote Sensing Laboratory in Las Vegas, Nevada, brought a Bomem model 304 interferometer to the SGP site. This new-generation interferometer could replace the AERI in the future. Analysis of performance data for the two systems is in progress.
Date: July 11, 2003
Creator: Holdridge, D. J.

Atmospheric Radiation Measurement Program facilities newsletter, March 2000

Description: The Atmospheric Radiation Measurement Program (ARM Program) is sending a copy of the ARM Video, an education overview of their program. In the video you will see and hear ARM scientists describe the importance of studying climate and climate change. It also contains a tour of some ARM sites and a look at state-of-the-art meteorological instrumentation, along with background information about the radiation budget and the complexity of climate modeling. The video was produced by the US Department of Energy.
Date: April 3, 2000
Creator: Sisterson, D. L.

Atmospheric Radiation Measurement Program Facilities newsletter, March 2001.

Description: The February 1998 issue of this newsletter discussed the Measurement of Pollution in the Troposphere (MOPITT) instrument that was to be tested at the SGP CART site before being launched aboard a NASA satellite to make precise, detailed measurements of tropospheric carbon monoxide and methane from space. The instrument was successfully launched on NASA's Terra satellite on December 18, 1999, by an Atlas IIAS rocket from Vandenberg Air Force Base in California and began collecting data at the end of February 2000. The instrument was designed by Dr. Jim Drummond, a physicist at the University of Toronto. The MOPITT Validation Exercise (MOVE) Campaign is schedule to take place at the SGP site from April 30 to May 18, 2001. Researchers will measure carbon monoxide by using instruments onboard the DOE Cessna Citation aircraft and other instruments located at the SGP CART. The data gathered will be compared with those collected by the MOPITT instrument to validate its performance thus far. MOPITT, which is scheduled for a five-year mission, will provide the first long-term global measurements of carbon monoxide and methane gas levels in roughly the lowest 10 miles of the atmosphere. Carbon monoxide and methane and their roles as greenhouse gases in global warming are of great interest. Greenhouse gases can trap escaping heat from Earth's surface, potentially increasing atmospheric temperatures. Carbon monoxide is a by-product of combustion, resulting primarily from industrial processing or biomass burning. Carbon monoxide levels in the atmosphere have been rising, indicating a problem. Normally, carbon monoxide is removed from the atmosphere by the hydroxyl radical, which can react with and remove many pollutants from the air.
Date: March 23, 2001
Creator: Holdridge, D.J.

Atmospheric radiation measurement program facilities newsletter, March 2002.

Description: International H2O Project (IHOP-2002)--The International H2O Project (IHOP-2002) will take place in west-central Oklahoma over 44 days, May 13-June 25, 2002. The main focus will be water vapor and its role in storm development and rainfall production, information needed to improve rainfall forecasting. Forecasting the amount and location of rainfall is difficult, particularly in the warm months, and improvements are urgently needed. Accurate prediction of floods would be very beneficial to society, because flooding is costly in terms of loss of life and property damage. Deaths resulting from flash flooding outnumber those from hurricanes, tornadoes, windstorms, or lightning, and damage due to flooding exceeds $5 billion annually. One measure of weather forecasting success is the accuracy of the Quantitative Precipitation Forecast (QPF), which predicts the amount of precipitation to be received at a certain location. One of the research goals of IHOP-2002 is to determine whether more accurate, detailed measurement of humidity will improve a computer model's ability to forecast rainfall amounts accurately. Current water vapor measurements are inadequate. The weather balloons (radiosondes) that gather most of the water vapor data used in today's weather and global climate models have three problems. First, the radiosonde stations are located too far apart, generating a grid of data that is too coarse to show the needed details in water vapor variability. Second, the radiosonde launches occur only every 12 hours, again providing too few data points for a highly variable parameter. Third, the radiosonde instrument has biases and inaccuracies in its measurements. Questionable data quality and data sets too coarse in both time and space make accurate forecasting difficult. The key to better, more accurate, higher-resolution water vapor measurements is dependable, ground-based sensors that operate continually and accurately. Such sensors will decrease dependence on sparsely spaced, costly weather balloon releases. IHOP-2002 will ...
Date: April 18, 2002
Creator: Holdridge, D. J.

Atmospheric Radiation Measurement Program facilities newsletter, May 2000.

Description: This month the authors will visit an ARM CART site with a pleasant climate: the Tropical Western Pacific (TWP) CART site, along the equator in the western Pacific Ocean. The TWP locale lies between 10 degrees North latitude and 10 degrees South latitude and extends from Indonesia east-ward beyond the international date line. This area was selected because it is in and around the Pacific warm pool, the area of warm sea-surface temperatures that determine El Nino/La Nina episodes. The warm pool also adds heat and moisture to the atmosphere and thus fuels cloud formation. Understanding the way tropical clouds and water vapor affect the solar radiation budget is a focus of the ARM Program. The two current island-based CART sites in the TWP are in Manus Province in Papua New Guinea and on Nauru Island.
Date: June 1, 2000
Creator: Sisterson, D.L.

Atmospheric Radiation Measurement Program facilities newsletter, May 2001.

Description: To help communities guard against the devastation that can result from severe weather, the National Weather Service (NWS) has developed a new program called StormReady. The aim is to build, at the community level, the communication and safety skills necessary to prevent loss of life and property in the event of severe weather. Each year weather-related disasters lead to 500 deaths and $14 billion in damage. The NWS hopes that prepared communities implementing StormReady can reduce these numbers when local emergency managers have clear-cut guidelines for improving their hazardous weather operations.
Date: June 1, 2001
Creator: Holdridge, D. J.

Atmospheric Radiation Measurement program facilities newsletter, May 2002.

Description: Eight eddy correlation (ECOR) flux measurement systems are now deployed throughout the ARM SGP CART site. These systems are used to determine the flux (flow) of sensible heat, the flux of latent heat, and air momentum just above cropland a few hundred feet upwind of the ECOR locations. Sensible heat is energy we feel as warmth. Latent heat is the energy that evaporated water vapor measured in the atmosphere. The ECOR systems actually measure wind velocity and temperature fluctuations, water vapor, and barometric pressure. The surface flux values for sensible heat, latent heat, and momentum are calculated from these measurements.
Date: June 3, 2002
Creator: Holdridge, D. J.

Atmospheric Radiation Measurement Program facilities newsletter, November 2000.

Description: Winter Weather Outlook--With the chill of colder temperatures in the air, we can rest assured that the icy grips of winter are just around the corner. The Climate Prediction Center (CPC), a specialized part of the National Weather Service (NWS), has issued its annual winter outlook for the 2000-2001 winter season. The CPC, located in Camp Springs, Maryland, is a government agency that focuses its predictions on Earth's climate. In comparison to the NWS forecasts of short-term weather events, the CPC goes farther into the future (from a week to seasons). The CPC conducts real-time monitoring of Earth's climate and makes predictions of climate variability over land and ocean and in the atmosphere. The CPC also evaluates the sources of major climate anomalies. The operations branch of the CPC prepares long-range forecasts by applying dynamical, empirical, and statistical techniques. The analysis branch performs applied research to identify physical factors responsible for climate fluctuations. The two branches work jointly to test new forecast methods and models, with the goal of improving model output. The CPC also evaluates the outlook for floods, droughts, hurricanes, ozone depletion, and El Nino and La Nina environments. So, what is the CPC outlook for winter 2000-2001? For the most part, winter weather will return to ''normal'' this season, because the El Nino and La Nina anomalies that shaped our past three winters have dissipated. Normal winter weather statistics are based on data for 1961-1990. The strong influence of the sea surface temperature in the tropical Pacific Ocean during an El Nino or La Nina episode, which makes it easier for forecasters to predict the trend for weather events, has given way to more neutral conditions. This winter, we should be prepared for swings in temperature and precipitation. The CPC is forecasting a more normal winter in ...
Date: December 1, 2000
Creator: Sisterson, D. L.

Atmospheric Radiation Measurement Program facilities newsletter, November 2002.

Description: Fall 2002 Intensive Operation Periods: Single Column Model and Unmanned Aerospace Vehicle--In an Intensive Operation Period (IOP) on November 3-23, 2002, researchers at the SGP CART site are collecting a detailed data set for use in improving the Single Column Model (SCM), a scaled-down climate model. The SCM represents one vertical column of air above Earth's surface and requires less computation time than a full-scale global climate model. Researchers first use the SCM to efficiently improve submodels of clouds, solar radiation transfer, and atmosphere-surface interactions, then implement the results in large-scale global models. With measured values for a starting point, the SCM predicts atmospheric variables during prescribed time periods. A computer calculates values for such quantities as the amount of solar radiation reaching the surface and predicts how clouds will evolve and interact with incoming light from the sun. Researchers compare the SCM's predictions with actual measurements made during the IOP, then adjust the submodels to make predictions more reliable. A second IOP conducted concurrently with the SCM IOP involves high-altitude, long-duration aircraft flights. The original plan was to use an unmanned aerospace vehicle (UAV), but the National Aeronautics and Space Administration (NASA) aircraft Proteus will be substituted because all UAVs have been deployed elsewhere. The UAV is a small, instrument-equipped, remote-control plane that is operated from the ground by a computer. The Proteus is a manned aircraft, originally designed to carry telecommunications relay equipment, that can be reconfigured for uses such as reconnaissance and surveillance, commercial imaging, launching of small space satellites, and atmospheric research. The plane is designed for two on-board pilots in a pressurized cabin, flying to altitudes up to 65,000 feet for as long as 18 hours. The Proteus has a variable wingspan of 77-92 feet and is 56 feet long. The plane can carry up ...
Date: December 3, 2002
Creator: Holdridge, D. J.

Atmospheric Radiation Measurement Program facilities newsletter, October 2000.

Description: Energy Balance Bowen Ratio System--Estimates of surface energy fluxes are a primary product of the data collection systems at the ARM SGP CART site. Surface fluxes tell researchers a great deal about the effects of interactions between the sun's energy and Earth. Surface fluxes of latent and sensible heat can be estimated by measuring temperature and relative humidity gradients across a vertical distance. Sensible heat is what we feel coming from a warm sidewalk or a metal car door; it can be measured with a thermometer. Latent heat, on the other hand, is released or absorbed during transformations such as the freezing of water into ice or the evaporation of morning dew from a lawn. Such a transformation is referred to as a ''phase change,'' the conversion of a substance among its solid, liquid, and vapor phases. Phase change is an important aspect of our climate. Earth's water cycle abounds with phase changes: rain falls and evaporates, changing from liquid to vapor; the water vapor in the air condenses to form clouds, changing from a gas into a liquid cloud droplet, and eventually falls to Earth's surface as rain or snow; snow falls and melts to liquid or sublimes directly to water vapor. This cyclic process has no end. Surface vegetation and land use play extremely important roles in surface energy fluxes. Plants absorb and reflect solar radiation and also take up water and expel water vapor. The type of plant material, its stage of growth, and its color determine whether and to what extent the surface and air can couple and exchange energy.
Date: November 9, 2000
Creator: Sisterson, D. L.

Atmospheric Radiation Measurement Program facilities newsletter, October 2001.

Description: Diffuse Shortwave Intensive Observation Period--The Diffuse Shortwave IOP ran from September 23 to October 12, 2001. During this IOP, Joe Michalsky (The State University of New York-Albany) and Tom Stoffel (National Renewable Energy Laboratory) deployed approximately 15 radiometers of various designs and manufacturers on the SGP Radiometer Calibration Facility. The purpose was to compare the accuracy of the radiometers for diffuse shortwave measurements. The Scripps Institution of Oceanography and Yankee Environmental Systems also participated in the IOP. SuomiNet Installations Completed--The installation of all SuomiNet equipment has been completed at 15 extended facility locations. Six of these stations are currently online and providing data to the SuomiNet project. SuomiNet is a university-based, real-time national global positioning system (GPS) network for atmospheric research and education. (See June 2000 issue of the ARM SGP Newsletter.) The network uses GPS to measure atmospheric moisture. To view real-time data from ARM sites, please visit this web site: http://www.gst.ucar.edu/gpsrg/realtime.html.
Date: October 29, 2001
Creator: Holdridge, D. J.

Atmospheric Radiation Measurement Program facilities newsletter, September 2000

Description: This is the third water vapor IOP and it will focus on the lower portions of the atmosphere. Again, scientists will work to achieve absolute calibrations of water vapor instrumentation. For this purpose, several instruments will be deployed, and measurements will be compared. Instruments to be used include radiosondes, Raman lidar, chilled-mirror hygrometers, surface meteorological observation station (SMOS) towers, a variety of microwave radiometers, and global positioning systems (GPS). The current experiment has two goals. The first is to characterize the accuracy of the water vapor measurements, especially the daily operational observations being made around the clock in the lower levels of the atmosphere at the CART site. The second goal is to develop techniques for improving the accuracy of these observations in order to obtain the best possible water vapor measurements under a wide range of atmospheric conditions.
Date: September 19, 2000
Creator: Sisterson, D. L. & Holdridge, D. J., ed.