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Title: Atmospheric Radiation Measurement Program facilities newsletter, July 2003.


This Monthly newsletter discusses the following three topics: (1) Representative Lucas and Senator Myers Support SGP Site; (2) Broadband Outdoor Radiometer Calibration (BORCAL) Takes Place at SGP; and (3) ARM Program Research Featured in ''Science'' Magazine.

Publication Date:
Research Org.:
Argonne National Lab., IL (US)
Sponsoring Org.:
US Department of Energy (US)
OSTI Identifier:
Report Number(s):
TRN: US200319%%365
DOE Contract Number:
Resource Type:
Technical Report
Resource Relation:
Other Information: PBD: 7 Aug 2003
Country of Publication:
United States

Citation Formats

Holdridge, D.J.. Atmospheric Radiation Measurement Program facilities newsletter, July 2003.. United States: N. p., 2003. Web. doi:10.2172/815666.
Holdridge, D.J.. Atmospheric Radiation Measurement Program facilities newsletter, July 2003.. United States. doi:10.2172/815666.
Holdridge, D.J.. Thu . "Atmospheric Radiation Measurement Program facilities newsletter, July 2003.". United States. doi:10.2172/815666.
title = {Atmospheric Radiation Measurement Program facilities newsletter, July 2003.},
author = {Holdridge, D.J.},
abstractNote = {This Monthly newsletter discusses the following three topics: (1) Representative Lucas and Senator Myers Support SGP Site; (2) Broadband Outdoor Radiometer Calibration (BORCAL) Takes Place at SGP; and (3) ARM Program Research Featured in ''Science'' Magazine.},
doi = {10.2172/815666},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Thu Aug 07 00:00:00 EDT 2003},
month = {Thu Aug 07 00:00:00 EDT 2003}

Technical Report:

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  • Cloudiness Inter-comparison IOP--Clouds are an important part of Earth's energy system. We take clouds for granted, but their role in weather and climate is considerable. Without clouds, life on Earth would be impossible. By helping to regulate surface temperatures, clouds establish livable conditions on the planet. Clouds produced by water vapor condensation play a complicated role in our climate system. Clouds decrease the amount of sunlight received by Earth's surface. Decreased sunlight reduces evaporation driven by sunlight and thus reduces cloud formation. With fewer clouds, Earth receives more sunlight, which eventually increases evaporation and cloud production. On the other hand,more » clouds also trap longwave (infrared) radiation emitted by Earth, as does water vapor. This heating effect increases evaporation. In summary, cloud formation is a complex, self-regulating, cyclic process. The SGP CART site is conducting a Cloudiness Inter-comparison IOP (intensive operational period) from mid-February through mid-April. The central facility near Lamont, Oklahoma, currently is home to several cloud-measuring instruments. The process of measuring cloudiness has always been somewhat subjective. Cloud measurements were once made by solely human observation, but new technology enables instruments to view the sky and make the more objective cloud measurements needed by both operational and research meteorologists. The SGP site currently operates eight different instruments that make cloud-related measurements. Data are collected on cloud cover, cloud top and base location, cloud water vapor and liquid water, sunshine duration and amount, and cloud number and area. During the Cloudiness Inter-comparison IOP, three additional cloud-measuring instruments are being brought to the CART site to be tested and assessed against the current instruments. Researchers are interested in testing whether the additional instruments can collect better data during nighttime hours, when visible light is not available for measurements. One of the three additional instruments is a commercially produced analyzer called the Nephelo. The Nephelo uses a series of infrared detectors to yield estimates of fractional sky cover. A second instrument to be tested is an infrared cloud imager. This instrument was previously deployed for testing at ARM's North Slope CART site in Barrow, Alaska. The third system to be tested will be a narrow-field-of-view infrared thermometer, operated in scanning mode rather than in the fixed vertical orientation. Scanning with the instrument and analyzing high-frequency samples of its data will increase the sky area covered. Collection of cloud data is not straightforward, because determination of actual cloud cover is subject to the definition of what is and is not a cloud. An instrument's determinations and calculations depend on its ability to detect a cloud either via collection of backscatter from a directed signal or by computer analysis of digital photographs. Verification of the data is restricted by the difficulty of the establishing a ''ground truth'' value. Thus, the emphasis in this IOP has to be on comparing measurements from the different instruments. Earth's climate is directly affected by the presence and absence of clouds. However, the accuracy of computer depictions and prognostications of future climate is limited by inadequacies in the parameterization of clouds in global climate models. A high-priority ARM Program goal is to increase our understanding of the interactions between clouds and solar radiation in the atmosphere, so that this complicated duo can be incorporated accurately into computer climate models.« less
  • 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 ormore » 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.« less
  • This Monthly newsletter discusses the following topic: New Atmospheric Profiling Instrument Added to SGP CART Suite--A new atmospheric profiling instrument at the SGP CART site is giving researchers an additional useful data stream. The new instrument is a microwave radiometer profiler (MWRP) developed by Radiometrics Corporation.
  • Summer research efforts continue in July with the SGP99 Hydrology Campaign headed by the US Department of Agriculture, Agricultural Research Service. Other participants are the National Aeronautics and Space Administration (NASA), the National Oceanic and Atmospheric Administration, and the ARM Program. This campaign focuses on measuring soil moisture by using satellite-based instruments and takes place July 7--22, 1999. Soil moisture is an important component of Earth's hydrologic cycle and climate, but the understanding of it and the ability to measure it accurately are limited. Scientists need to understand soil moisture better so that it can be incorporated correctly into generalmore » circulation models. As an important factor in growing crops, soil moisture dictates a farmer's success or failure. Too much soil moisture can drown out croplands and cause flooding, whereas too little can lead to drought conditions, robbing crops of their life-supporting water. Decisions about which crops to plant and other land use issues depend on the understanding of soil moisture patterns. Soil moisture can be measured in various ways. ARM employs several direct methods using soil moisture probes buried from 1 inch to 6.5 feet below the surface. One type of probe has two stainless steel screens separated by a piece of fiberglass. Electrical resistance, which is a function of soil moisture content, is measured between the screens. Another type of probe measures soil temperature and the increase in temperature after the soil is heated by small heating element. From this measurement, the volume of water in the soil can be calculated.« less
  • For improved safety in and around the ARM SGP CART site, the ARM Program recently purchased and installed an aircraft detection radar system at the central facility near Lamont, Oklahoma. The new system will enhance safety measures already in place at the central facility. The SGP CART site, especially the central facility, houses several instruments employing laser technology. These instruments are designed to be eye-safe and are not a hazard to personnel at the site or pilots of low-flying aircraft over the site. However, some of the specialized equipment brought to the central facility by visiting scientists during scheduled intensivemore » observation periods (IOPs) might use higher-power laser beams that point skyward to make measurements of clouds or aerosols in the atmosphere. If these beams were to strike the eye of a person in an aircraft flying above the instrument, damage to the person's eyesight could result. During IOPs, CART site personnel have obtained Federal Aviation Administration (FAA) approval to temporarily close the airspace directly over the central facility and keep aircraft from flying into the path of the instrument's laser beam. Information about the blocked airspace is easily transmitted to commercial aircraft, but that does not guarantee that the airspace remains completely plane-free. For this reason, during IOPs in which non-eye-safe lasers were in use in the past, ARM technicians watched for low-flying aircraft in and around the airspace over the central facility. If the technicians spotted such an aircraft, they would manually trigger a safety shutter to block the laser beam's path skyward until the plane had cleared the area.« less