PAM I and II Project Overviews

Project PRESTORM Dr. William Cotton, and Dr. Richard Johnson Dept. of Atmospheric Science Colorado State University

Prestorm occurred during May and June, of 1985 and was centered around and to the south of Witchita, Kansas. It involved fourty-two PAMII stations, and for the first time, the full PAM field base station. The stations were deployed in the midst of other observing systems including rawindsondes, profilers, doppler radars, lightning detection systems, and aircraft. Two PAM stations were co-located with NSSL Surface Automated Mesonet stations (SAM) in the southern portion of the network. The objectives of the study were to deploy, operate and coordinate the efforts of a large collection of measurement systems over a regional area as a preliminary shakeout of techniques to be utilized in the full scale STORM experiment. The broad science effort involved forecasting, detection and intensive study of midwestern mesoscale convective storm systems (including super-cells and storm clusters), from their development through their evolution. Data collected by the PAM network was of high quality, but one noteworthy problem was discovered. Wet bulb errors were induced by brass sleeves used to protect the PRTs from moisture damage. Once discovered, extensive in-field intercomparison data were taken using Assman psychrometers. This technique permitted data correction to be employed to adjust the original PAM wet bulb data set.

 

Project NADO Mr. Skip Spensley Airport Expansion Office Bridge Building, Room 300 Stapleton International Airport

NADO involved two PAM stations from July, 1985, through August, 1986. These were setup to the northeast of the Denver-metro area; in the vicinity of Denver's new airport. The intension of the experiment was to provide long-term, seasonal wind information to the Airport Expansion Group to assist them in planning for the new airport. These data were intended to help locate runways, and formulate wind-rose information within the area to be developed.

 

Project RYBICA WHEATFIELD Dr. Tony Delany and Dr. Patrick Zimmerman NCAR/ACD

One PAM station was deployed from January, 1985 through December, 1986 in a wheat field approximately fifty miles east of Brighton, Colorado. The intention of this study was to examine trace gas transport to and from the atmosphere throughout the growth cycle of a food crop. A special analog sensing interface was added to the PAM station to permit atmospheric chemistry data (carbon monoxide, nuclei, and ozone) to be included with the standard PAM data set. These data were not directly involved in flux measurements, but rather provided background climatological data, and indications of pollution levels.

 

Project SIERRA Dr. John Marwitz Dept. of Atmospheric Science University of Wyoming Dr. Dave Renolds U.S. Bureau of Reclamation

The Sierra cooperative pilot field project was operational from February through March of 1985. One PAM station was deployed in association with a dual doppler radar to provide background and surface reference data as an adjunct to the radar measurements. The project focused on the study of convective storm activity over the Sierra Nevada mountains with the intention of investigating the feasibility of precipitation enhancement.

 

Project GALE Dr. Gerald Watson Dept. of Marine, Earth, & Atmospheric Sciences North Carolina State University

The GALE field project consisted of fifty PAMII stations in a network extending from Virginia to South Carolina, spaced approximately 50 kilometer apart. As part of the large scale project operations command and control, the full PAM field base was co-located with the main GALE headquarters in Raleigh, North Carolina. In addition, for the first time, the Compact Base station was deployed with a doppler radar near Cape Hatterass. GALE operations lasted from January through mid-March, 1986. The primary thrust of the experiment was the intensive study of the genesis of wintertime mid-atlantic low pressure systems and resultant cyclonic activity, frontal effects and moisture patterns. A major emphasis was the improvement of forecasting techniques of these circulation systems, and their associated weather patterns. A limited number of PAM stations were outfitted with experimental humicap type humidity sensors, and multiple tipping bucket rain gauges configured to determine effectiveness of wind shielding hardware.

 

Project MIST Dr. Theodore Fujita University of Chicago Dept. of Geophysical Sciences Dr. Roger Wakimoto Dept. of Atmospheric Sciences University of California

Project MIST involved fourty-one PAMII stations arranged in a dense cluster around the Huntsville, Alabama airport during June and July, 1986. The full PAM field base was deployed with one of the doppler radars, and an aircraft tracking system, and served as the operational headquarters. The experiment targeted the study of microburst and severe thunderstorm activity, particularly as it applied to airport operations, and aircraft safety. PAMII stations sampled data on one-minute intervals, and transmitted messages every three minutes: both a maximum utilization of the system's capacity over the GOES telemetry link. Special sensing included an extension of the GALE rain gauge network and humicap devices.

 

Project SPACE Dr. Jim Arnold, and Mr. Steve Williams NASA, Marshall Space Flight Center

The Space project operated as an adjuct to the Mist experiment. Nine PAMII stations were deployed in a wide circle around Huntsville, Alabama, about 75 km apart. The intention of the experiment was to intercompare ground based meteorological and radiometric data with satellite based sensors for precipitation and cloud cover studies. PAM stations were equipped with Epply pyranometers provided by NASA in addition to their normal complement of sensors. The stations were co-located with beta rawinsonde units. Data provided by these stations proved to be of high quality. Initially, however, there was a noise insertion problem within some of the radiometer readings due to the ten-second transmission of data every five minutes. This was corrected by improved shielding techniques within the sensor's cabling.

 

Project CARP Dr. Joost Businger NCAR/ATD/SSSF

Four PAMII stations were deployed near Carpenter, Wyoming in a one-mile square network during September and October, 1986. These stations provided background meteorological information and were used in particular to determine the convergence of the wind field and to provide a calibration check of the user sensors involved in the experiment. This study consisted of fine-scale surface layer measurements to determine the Von Karman constant and characterize the exchange processes in the atmospheric surface layer.

 

Project ABLE Dr. Michael Garstang Dept. of Environmental Sciences University of Virginia

Four PAMII stations were located near Manaus, Brazil during April through May, 1987, in support of NASA's ABLE-IIB experiment. The purpose of the ABLE experiment was the study of convective transport of trace gases (surface, and cloud mass transports) and the heat and water vapor budget within the Amazonian Basin during the rainy season. This experiment was one of several field projects involved in NASA's larger Tropospheric Chemistry Program. The PAM stations were adapted for mounting on top of 45 meter Rohn towers in order to locate the sensors above the dense tropical forrest canopy. They provided basic meteorological data, in one-minute averages, to augment other sensing systems such as tethered balloons, rawinsondes, GMDs, aircraft, and a host of atmospheric chemistry equipment. Data telemetered to Boulder, Colorado were accessed by scientists in Manaus using NCAR analysis software and relayed as real-time interactive displays to Manaus by a NASA communications link.

 

Project CINDE Dr. John McCarthy and Dr. Jim Wilson (?) National Center for Atmospheric Research

Forty-six PAM stations were involved in the Convective Initiation Experiment during June through mid-August, 1987.

 

Project FIFE Dr. Forrest Hall and Dr. Piers Sellers NASA/GSFC Dr. Blaine Blad Center for Agricultural Meteorology and Climatology University of Nebraska

The First ISLSCP Field Experiment performed by NASA involved 12 PAMII stations from March, 1987 through November, 1988. It continues to operate with 8 stations through the summer of 1989. These stations are arranged in a modest network around the Konza Natural Grasslands Area immediately south of Manhatten, Kansas. The PAM Compact Base Station was deployed at Kansas State University during the summer of 1987 in support of intensive field operations. The FIFE experiment involves a host of investigators studying a wide variety of phenomenon involved in argricultural and climatological research such as surface radiation biology and soil moisture, surface aerosol transport, and ground based intercomparisons for satellite sensing systems. PAM stations were highly modified in support of this study. Special analog sensing boards were installed in the remote stations to permit interfacing of radiometric sensors (long and shortwave global, diffuse, reflected, photosynthetically active and net radiation), and soil temperature sensors. For the first time, PAM stations recorded the w-wind component as well. During wintertime operations, Rotronic humicap temperature and humidity sensors were installed. In Boulder, NCAR was called upon to receive and archive data telemetered over the GOES system from U.S.Army Corps of Engineers platforms which were part of the study.

 

Project VALI Dr. Gabor Vali Dept. of Atmospheric Sciences University of Wyoming

The In Cloud Oxidation Experiment has made use of a single PAM station throughout 1988 to support field measurements for the study of in-cloud sulphur dioxide oxidation. The station, located on Elk Mountain approximately 80 miles north-west of Laramie, has been used to thermodynamically estimate the cloud base height and evaluate the investigator's plume release experiments. Researchers have also utilized the PAM wind and temperature readings to determine the optimal conditions in which to release tracer gases for dispersion. These studies are significant in their contribution toward quantifying the yields of acid sulfate in orographic clouds and understanding acidic deposition. The PAM station was adapted with a Rotronic humidity sensor to provide data in sub-freezing conditions, as well as an Epply pyranometer. Investigators have routinely accessed the NCAR computer base to recover PAM data via modem from Laramie.

 

Project POPE Dr. Brian Ridley NCAR/ACD

The Pacific Ocean Photochemistry Experiment required ground based meterological observations in conjunction with air sampling equipment for the study of the Pacific air mass near Hawaii's Mauna Loa Observatory from April through May, 1988. To fulfill this requirement, a standard PAM station was modified to permit direct downloading of data into the NCAR/ACD computers located on site, thereby providing more representative readings than could be obtained from the observatory. These PAM data were important in the determination of the boundary layer position to differentiate between air masses which were contaminated by the island versus the cleaner free troposphere. The experiment's goal was to expand the data base of information involving the photochemical relationship between the major odd nitrogen, odd hydrogen and odd oxygen species, remote tropospheric production and the loss of ozone. PAM Data were simultaneously transmitted to Boulder, Colorado which permitted SSSF personnel to examine the data integrity and better support the project.

 

Project SMILE Surface Mixed Layer Experiment (SMILE) Dr. Clive Dorman

Carl Friehe (University of California) and Clive Dorman (San Diego State University) utilized five PAM remote stations, one CLASS sounding system, and the PAM Compact Base station along the coast of northern California to investigate the effects of the lower atmosphere on the upper ocean layer over the continental shelf. The PAM stations were operated between November 1988 and July 1989, and the CLASS and Compact Base systems were on-site during intensive field operations between mid-February and mid-March 1989. Several hardware and electronic modifications were made to the PAM remote stations in anticipation of, and response to difficulties associated with the harsh marine environment. PAM data were used to estimate the marine boundary layer thickness, and to correlate mesoscale changes in the boundary layer with upper ocean changes, and to monitor the stability of the boundary layer between winter storms. The data were also needed to observe the near surface wind structure, particularly the variations within coastal storms. The stations were configured to record standard meteorological parameters in one-minute sampling intervals. CLASS was used to measure the marine atmospheric boundary layer thickness and the general structure of storm systems. The flights also assisted in the observation of cross coast circulation patterns and in the determination of wind stability. Between two and four soundings were flown each day by the investigator's personnel. The PAM Compact Base was also operated by project personnel. It was located at the Santa Rosa airport and was used for on-site weather observations and to assist aircraft operations.

 

Project SMOG Dr. Russell Dickerson

Dr. Russell Dickerson (University of Maryland) obtained the use of one PAM station for the study of trace gas constituents in the Shenanhoah National Park beginning in September, 1988. The study, denoted SMOG, is sponsored by the Environmental Protection Agency. Its objective is the observation of photochemical ozone production and reactive nitrogen compounds for modeling the origin and disposition of important gases which influence global climate and air quality. The PAMII station was extensively modified in order to meet scientific objectives. Analog digitization was added to acquire data from user sensors monitoring ozone, carbon-monoxide, nitric oxide and hydroxyl radical concentrations. Thirty-second data averages were obtained on a PAMII station for the first time. The data, telemetered every three minutes to NCAR's GOES receiving system, were observed by project personnel in near-real-time using NCAR analysis software over a high speed network connection with Maryland. NCAR support for Dr. Dickerson extends beyond the use of PAM. The ROBOT software package is being made available for data analysis on University of Maryland computers. Because SMOG field measurements will be needed for several years, NCAR is providing Dr. Dickerson with technical assistance in acquiring suitable hardware for an independent data monitoring system. [from a write-up by Dr. Dickerson...]

"SMOG" DICKERSON 1987-1990 EPA PROJECT SUMMARY Photochemical ozone production, or "smog", plays an important role in air quality and global climate. Reactive nitrogen compounds are key catalysts in ozone production, but the critical concentrations are well below the detection limit of commercial instruments, and measurements are sparse; very little is known of background concentrations over the Central Atlantic region of the United States. Without accurate data on nitrogen species, models cannot produce accurate simulations of ozone (O3) or hydroxyl radical (OH) concentrations. We propose to measure nitric oxide (NO), total reactive nitrogen (NOy), carbon monoxide (CO), ozone, and meteorological parameters from a mobile laboratory at an appropriate site in rural Virginia, (Shenandoah National Park) over month long periods in summer and in winter. Results will be analyzed in terms of atmospheric photochemistry and dynamics. We will also develop and test a system to monitor the instruments so that these measurements can be made at this and other remote locations without an expert continuously on site. To determine the origins and fates of the trace gases measured, back trajectories and a novel statistical technique will be used. These analyses will complement several related but independent research projects currently underway in the area.

1990-1993 EPA PROJECT SUMMARY Ozone (O3) in the troposphere is both a noxious pollutant and a greenhouse gas. Photochemical reactions involving odd nitrogen compounds and carbon monoxide (CO) or hydrocarbons produce ozone-containing "smog." The critical concentrations of these O3 precursors are well below the detection limit of commercial instruments. The resulting paucity of data for air over rural areas of the Eastern United States and the Western Atlantic Ocean limits our understanding of tropospheric O3 and other oxidants such as the hydroxyl radical OH. With previous EPA support we developed a mobile laboratory and fast communications link (based on an Portable Automated Mesonet, PAMII, station) for unattended monitoring of trace gases at a remote site. We measured nitric oxide (NO), total reactive nitrogen (NOy), CO, O3, and meteorological parameters at the Big Meadows site in Shenandoah National Park, Virginia for a full year, and purchased a clone of a PAMII station. Nitric acid, alkyl nitrates, and nonmethane hydrocarbons were also measured for short periods. This proposal requests support for continued analysis of the data and further development of the remote monitoring system. We will then take the system to the AEROCE (Atmosphere Ocean Chemistry Experiment) site in Bermuda for the spring/summer season of 1991 and 1992 to study the fate of pollutants after they have left the North American continent. This ground station will support the TIBEX aircraft project.

 

Project BAQ

Boulder Air Quality (BAQ) experiment was located near Boulder, Colorado.  The goal was a study of winter air quality along the Front Range of Colorado.

 

Project WISP Winter Icing Studies Program NCAR/RAP, FAA, Dr. Jim Wilson

The Winter Icing and Storms Project (WISP) utilized nineteen PAM stations and four CLASS systems during February and March, 1990. It was the first in a series of deployments sponsored principally by NCAR's Research Applications Program, NOAA, and the FAA, with a variety of university support. It's primary goals are to investigate the production and depletion of supercooled liquid water in winter storms and thereby enhance aircraft safety through improved forecasts of icing conditions. PAM stations were deployed in a variety of configurations during WISP. Fifteen had Rotronic humicaps to permit humidity measurements below freezing when wet bulb data are lost; six had a combined rain and snow gauge instead of standard tipping buckets. Rotronic performance was good for humidity measurements but their temperature accuracy was insufficient despite several efforts to improve the readings with enhanced aspiration and various air-filters and radiation shields. The PAM dry bulb remained the primary measurement of air temperature. Other attempts were made to improve psychrometer performance below freezing by using a 10% alcohol solution instead of straight distilled water. This proved ineffective because temperatures quickly dropped below the solution's freezing level and an even higher alcohol content would have disrupted sensor accuracy. Overall PAM data recovery was good however, averaging 95%, although freezing and icing became a problem on several occasions effecting sensors, radios and batteries. Seven sites were operated with commercial A/C power which was required for the heated snow gauges. Snow gauge performance was mixed. During WISP a computerized data-base was utilized by PAM technicians for the first time to help document station visits and intercomparison readings. Approximately 300 soundings were taken from the 4 CLASS sites during WISP. Overall data quality and recovery was quite good. Freezing rain and icing of the ground-based equipment did cause some degradation of the data as well as missing flights. In severe cases of icing the hatches on the CLASS trailers would freeze closed, making balloon launches impossible. Ice on the ground antennas had a tendency to short the received signal to ground, causing periods of poor reception. It was noted during the project that winds would often be lost when the radiosonde entered storm clouds. Atmospheric noise increased dramatically when this happened, causing poor LORAN reception, subsequently poor wind data. This phenonema is well documented when releasing sondes in or near thunderstorms but has not been as noticeable when operating in the winter in stratiform clouds.