Atmospheric Radiation Measurement Program Facilities Newsletter, December 1999 PDF Download
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Author: Publisher: ISBN: Category : Languages : en Pages : 4
Book Description
This issue continues the discussion on lightning begun with the last issue. It reviews briefly what lightning is, then discusses protecting buildings and structures, personal protection, and protecting ARM structures. Five sources for more information are listed.
Author: Publisher: ISBN: Category : Languages : en Pages : 4
Book Description
This issue continues the discussion on lightning begun with the last issue. It reviews briefly what lightning is, then discusses protecting buildings and structures, personal protection, and protecting ARM structures. Five sources for more information are listed.
Author: Publisher: ISBN: Category : Languages : en Pages : 4
Book Description
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 general 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.
Author: Publisher: ISBN: Category : Languages : en Pages : 3
Book Description
This newletter begins a discussion on Lightning--Natures's light show. This issue explains what lightning is. Fortunately, lightning strikes on ARM's instruments occurs infrequently. Next month's issue will explain lightning safety and how ARM has dealt with lightning safety.
Author: Publisher: ISBN: Category : Languages : en Pages : 5
Book Description
The Atmospheric Radiation Measurement Program September 1999 Facilities Newsletter discusses the several Intensive Observation Periods (IOPs) that the ARM SGP CART site will host in the near future. Two projects of note are the International Pyrgeometer Intercomparison and the Fall Single Column Model (SCM)/Nocturnal Boundary Layer (NBL) IOP. Both projects will bring many US and international scientists to the SGP CART site to participate in atmospheric research.
Author: Publisher: ISBN: Category : Languages : en Pages : 5
Book Description
With the end of summer drawing near, the fall songbird migration season will soon begin. Scientists with the ARM Program will be able to observe the onset of the migration season as interference in the radar wind profiler (RWP) data. An RWP measures vertical profiles of wind and temperature directly above the radar from approximately 300 feet to 3 miles above the ground. The RWP accomplishes this by sending a pulse of electromagnetic energy skyward. Under normal conditions, the energy is scattered by targets in the atmosphere. Targets generally consist of atmospheric irregularities such as variations in temperature, humidity, and pressure over relatively short distances. During the spring and fall bird migration seasons, RWP beam signals are susceptible to overflying birds. The radar beams do not harm the birds, but the birds' presence hampers data collection by providing false targets to reflect the RWP beam, introducing errors into the data. Because of the wavelength of the molar beam, the number of individuals, and the small size of songbirds' bodies (compared to the larger geese or hawks), songbirds are quite likely to be sampled by the radar. Migrating birds usually fly with the prevailing wind, making their travel easier. As a result, winds from the south are ''enhanced'' or overestimated in the spring as the migrating birds travel northward, and winds from the north are overestimated in the fall as birds make their way south. This fact is easily confirmed by comparison of RWP wind data to wind data gathered by weather balloons, which are not affected by birds.
Author: Publisher: ISBN: Category : Languages : en Pages : 5
Book 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.
Author: Publisher: ISBN: Category : Languages : en Pages : 5
Book Description
This issue of the Atmospheric Radiation Measurement Program (ARM Program) monthly newsletter is about the ARM Program goal to improve scientific understanding of the interactions of sunlight (solar radiation) with the atmosphere, then incorporate this understanding into computer models of climate change. To model climate accurately all around the globe, a variety of data must be collected from many locations on Earth. For its Cloud and Radiation Testbed (CART) sites, ARM chose locations in the US Southern Great Plains, the North Slope of Alaska, and the Tropical Western Pacific Ocean to represent different climate types around the world. In this newsletter they consider the North Slope of Alaska site, with locations at Barrow and Atqasuk, Alaska.
Author: Publisher: ISBN: Category : Languages : en Pages : 2
Book Description
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 intensive 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.
Author: Publisher: ISBN: Category : Languages : en Pages : 5
Book 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 weather and atmospheric parameters that will, in turn, improve the accuracy and quality of weather forecasts. A satellite-based instrument is cost-effective because it can provide continuous global measurements, eliminating isolated yet costly weather balloon releases. Aqua, launched from Vandenberg Air Force Base in California (Figure 2), carries six state-of-the-art instruments that measure various water vapor parameters: (1) AIRS, which measures atmospheric temperature and humidity, land and sea surface temperatures, cloud properties, and radiative energy flux; (2) Advanced Microwave Sounding Unit, which measures atmospheric temperature and humidity during both cloudy and cloud-free periods; (3) Advanced Microwave Scanning Radiometer, which measures cloud properties, radiative energy flux, precipitation rates, land surface wetness, sea ice, snow cover, sea surface temperature, and wind fields; (4) Clouds and the Earth's Radiant Energy System, which measures radiative energy flux; (5) Humidity Sounder for Brazil, which measures atmospheric humidity by using a passive scanning microwave radiometer; and (6) Moderate Resolution Imaging Spectroradiometer, which measures cloud properties, radiative energy flux, aerosol properties, land cover and land use change, vegetation dynamics, land surface temperature, fire occurrence, volcanic effects, sea surface temperature, ocean color, snow cover, atmospheric temperature and humidity, and sea ice. The data-gathering capabilities of the Aqua instruments will provide an unprecedented view of atmosphere-land interactions (Figure 3). The availability of more frequent, more accurate global measurements of important atmospheric parameters will both improve our capabilities for short-term weather forecasting and lead to a better understanding of climate variability and climate change. Simultaneous measurements of many parameters will allow scientists to study complicated forcings and feedbacks of the atmosphere, which can be integrated into climate models.
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