Evaluation of the filter pack for long-duration sampling of ambient air

1999 ◽  
Vol 33 (14) ◽  
pp. 2187-2202 ◽  
Author(s):  
J.E. Sickles, II ◽  
L.L. Hodson ◽  
L.M. Vorburger
Keyword(s):  
Ambient Air ◽  
Filter Pack ◽  
Long Duration

scholarly journals Overview of and first observations from the TILDAE High-Altitude Balloon Mission

2017 ◽  
Vol 10 (4) ◽  
pp. 1595-1607 ◽  
Author(s):  
Bennett A. Maruca ◽  
Raffaele Marino ◽  
David Sundkvist ◽  
Niharika H. Godbole ◽  
Stephane Constantin ◽  
...  
Keyword(s):  
Sonic Anemometer ◽  
Ambient Air ◽  
Small Scale ◽  
New Paradigm ◽  
Intermittent Turbulence ◽  
Atmospheric Measurements ◽  
Long Duration ◽  
In Situ Observations ◽  
Robust Separation

Abstract. Though the presence of intermittent turbulence in the stratosphere has been well established, much remains unknown about it. In situ observations of this phenomenon, which have provided the greatest details of it, have mostly been achieved via sounding balloons (i.e., small balloons which burst at peak altitude) carrying constant-temperature hot-wire anemometers (CTAs). The Turbulence and Intermittency Long-Duration Atmospheric Experiment (TILDAE) was developed to test a new paradigm for stratospheric observations. Rather than flying on a sounding balloon, TILDAE was incorporated as an add-on experiment to the payload of a NASA long-duration balloon mission that launched in January 2016 from McMurdo Station, Antarctica. Furthermore, TILDAE's key instrument was a sonic anemometer, which (relative to a CTA) provides better-calibrated measurements of wind velocity and a more robust separation of velocity components. During the balloon's ascent, TILDAE's sonic anemometer provided atmospheric measurements up to an altitude of about 18 km, beyond which the ambient air pressure was too low for the instrument to function properly. Efforts are currently underway to scientifically analyze these observations of small-scale fluctuations in the troposphere, tropopause, and stratosphere and to develop strategies for increasing the maximum operating altitude of the sonic anemometer.

scholarly journals An assessment of the performance of the Monitor for AeRosols and GAses in ambient air (MARGA): a semi-continuous method for soluble compounds

2014 ◽  
Vol 14 (11) ◽  
pp. 5639-5658 ◽  
Author(s):  
I. C. Rumsey ◽  
K. A. Cowen ◽  
J. T. Walker ◽  
T. J. Kelly ◽  
E. A. Hanft ◽  
...  
Keyword(s):  
Linear Regression ◽  
Ambient Air ◽  
Water Soluble ◽  
Performance Goal ◽  
Filter Pack ◽  
Accuracy And Precision ◽  
The Us ◽  
Us Epa ◽  
Best Fit ◽  
A Performance

Abstract. Ambient air monitoring as part of the US Environmental Protection Agency's (US EPA's) Clean Air Status and Trends Network (CASTNet) currently uses filter packs to measure weekly integrated concentrations. The US EPA is interested in supplementing CASTNet with semi-continuous monitoring systems at select sites to characterize atmospheric chemistry and deposition of nitrogen and sulfur compounds at higher time resolution than the filter pack. The Monitor for AeRosols and GAses in ambient air (MARGA) measures water-soluble gases and aerosols at an hourly temporal resolution. The performance of the MARGA was assessed under the US EPA Environmental Technology Verification (ETV) program. The assessment was conducted in Research Triangle Park, North Carolina, from 8 September to 8 October 2010 and focused on gaseous SO2, HNO3, and NH3 and aerosol SO42-, NO3-, and NH4+. Precision of the MARGA was evaluated by calculating the median absolute relative percent difference (MARPD) between paired hourly results from duplicate MARGA units (MUs), with a performance goal of ≤ 25%. The accuracy of the MARGA was evaluated by calculating the MARPD for each MU relative to the average of the duplicate denuder/filter pack concentrations, with a performance goal of ≤ 40%. Accuracy was also evaluated by using linear regression, where MU concentrations were plotted against the average of the duplicate denuder/filter pack concentrations. From this, a linear least squares line of best fit was applied. The goal was for the slope of the line of best fit to be between 0.8 and 1.2. The MARGA performed well in comparison to the denuder/filter pack for SO2, SO42−, and NH4+, with all three compounds passing the accuracy and precision goals by a significant margin. The performance of the MARGA in measuring NO3- could not be evaluated due to the different sampling efficiency of coarse NO3- by the MUs and the filter pack. Estimates of "fine" NO3- were calculated for the MUs and the filter pack. Using this and results from a previous study, it is concluded that if the MUs and the filter pack were sampling the same particle size, the MUs would have good agreement in terms of precision and accuracy. The MARGA performed moderately well in measuring HNO3 and NH3, though neither met the linear regression slope goals. However, recommendations for improving the measurement of HNO3 and NH3 are discussed. It is concluded that SO42-, SO2, NO3-, HNO3, NH4+, and NH3 concentrations can be measured with acceptable accuracy and precision when the MARGA is operated in conjunction with the recommendations outlined in the manuscript.

scholarly journals An assessment of the performance of the Monitor for AeRosols and GAses in ambient air (MARGA): a semi-continuous method for soluble compounds

2013 ◽  
Vol 13 (9) ◽  
pp. 25067-25124 ◽  
Author(s):  
I. C. Rumsey ◽  
K. A. Cowen ◽  
J. T. Walker ◽  
T. J. Kelly ◽  
E. A. Hanft ◽  
...  
Keyword(s):  
Linear Regression ◽  
Ambient Air ◽  
Performance Goal ◽  
Filter Pack ◽  
Accuracy And Precision ◽  
The Us ◽  
Percent Difference ◽  
Relative Percent Difference ◽  
Us Epa ◽  
Best Fit

Abstract. Ambient air monitoring as part of the US Environmental Protection Agency's (US EPA's) Clean Air Status and Trends Network (CASTNet) currently uses filter packs to measure weekly integrated concentrations. The US EPA is interested in supplementing CASTNet with semi-continuous monitoring systems at select sites to characterize atmospheric chemistry and deposition of nitrogen and sulfur compounds at higher time resolution than the filter pack. The Monitor for AeRosols and GAses in ambient air (MARGA) measures water-soluble gases and aerosols at hourly temporal resolution. The performance of the MARGA was assessed under the US EPA Environmental Technology Verification (ETV) program. The assessment was conducted in Research Triangle Park, North Carolina from 8 September–8 October 2010 and focused on gaseous SO2, HNO3 and NH3 and aerosol SO4−, NO3− and NH4+. Precision of the MARGA was evaluated by calculating the median absolute relative percent difference (MARPD) between paired hourly results from duplicate MARGA units (MUs), with a performance goal of <25%. The accuracy of the MARGA was evaluated by calculating the median absolute relative percent difference (MARPD) for each MU relative to the average of the duplicate denuder/filter pack concentrations, with a performance goal of ≤40%. Accuracy was also evaluated by using linear regression, where MU concentrations were plotted against the average of the duplicate denuder/filter pack concentrations. From this, a linear least squares line of best fit was applied. The goal was for the slope of the line of best fit to be between 0.8 and 1.2. The MARGA performed well in comparison to the denuder/filter pack for SO2, SO42− and NH4+, with all three compounds passing the accuracy and precision goals by a significant margin. The performance of the MARGA in measuring NO3− could not be evaluated due to the different sampling efficiency of coarse NO3− by the MUs and the filter pack. Estimates of "fine" NO3− were calculated for the MUs and the filter pack. Using this and results from a previous study, it is concluded that if the MUs and the filter pack were sampling the same particle size, the MUs would have good agreement in terms of precision and accuracy. The MARGA performed moderately well in measuring HNO3 and NH3, though neither met the linear regression slope goals. However, recommendations for improving the measurement of HNO3 and NH3 are discussed. It is concluded that SO42−, SO2, NO3−, HNO3, NH4+ and NH3 concentrations can be measured with acceptable accuracy and precision when the MARGA is operated in conjunction with the recommendations outlined in the manuscript.

scholarly journals Model Inter-Comparison for PM2.5 Components over urban Areas in Japan in the J-STREAM Framework

Atmosphere ◽  
2020 ◽  
Vol 11 (3) ◽  
pp. 222 ◽  
Author(s):  
Kazuyo Yamaji ◽  
Satoru Chatani ◽  
Syuichi Itahashi ◽  
Masahiko Saito ◽  
Masayuki Takigawa ◽  
...  
Keyword(s):  
Urban Areas ◽  
Atmospheric Stability ◽  
Model Performance ◽  
Ambient Air ◽  
Atmospheric Pollutants ◽  
Pollution Monitoring ◽  
Ambient Air Pollution ◽  
Air Pollution Monitoring ◽  
Filter Pack ◽  
Good Agreement

A model inter-comparison of secondary pollutant simulations over urban areas in Japan, the first phase of Japan’s study for reference air quality modeling (J-STREAM Phase I), was conducted using 32 model settings. Simulated hourly concentrations of nitric oxide (NO) and nitrogen dioxide (NO2), which are primary pollutant precursors of particulate matter with a diameter of 2.5 µm or less (PM2.5), showed good agreement with the observed concentrations, but most of the simulated hourly sulfur oxide (SO2) concentrations were much higher than the observations. Simulated concentrations of PM2.5 and its components were compared to daily observed concentrations by using the filter pack method at selected ambient air pollution monitoring stations (AAPMSs) for each season. In general, most models showed good agreement with the observed total PM2.5 mass concentration levels in each season and provided goal or criteria levels of model ensemble statistics in warmer seasons. The good performances of these models were associated with the simulated reproducibility of some dominant components, sulfates (SO42−) and ammonium (NH4+). The other simulated PM2.5 components, i.e., nitrates (NO3−), elemental carbon (EC), and organic carbon (OC), often show clear deviations from the observations. The considerable underestimations (approximately 30 µg/m3 for total PM2.5) of all participant models found on heavily polluted days with approximately 40–50 µg/m3 for total PM2.5 indicated some problems in the simulated local meteorology such as the atmospheric stability. This model inter-comparison suggests that these deviations may be owing to a need for further improvements both in the emission inventories and additional formation pathways in chemical transport models, and meteorological conditions also require improvement to simulate elevated atmospheric pollutants. Additional accumulated observations are likely needed to further evaluate the simulated concentrations and improve the model performance.

scholarly journals Development of HVAC Diffuser Unit for Task and Ambient Air Conditioning Allowing User to Control Built-in Fan — Evaluation of Air Supply Mode by Subjective Experiment and Field Measurement in Office

2019 ◽  
Vol 111 ◽  
pp. 01025 ◽  
Author(s):  
Takashi Akimoto ◽  
Naoya Odagiri ◽  
Yoichi Nakashima ◽  
Seiji Miyazaki ◽  
Takashi Yanai ◽  
...  
Keyword(s):  
Air Conditioning ◽  
Field Measurements ◽  
Ambient Air ◽  
Air Supply ◽  
Long Duration ◽  
Subjective Experiment ◽  
Supply Mode ◽  
Strong Mode ◽  
Fluctuation Mode ◽  
Dual Functions

HVAC diffusers have been developed that have dual functions for task and ambient air conditioning. In this study, we evaluated comfort according to air supply mode, strong or fluctuation mode, through a subjective experiment. We found that the fluctuation mode maintained greater comfort for longer compared with the strong mode under continuous airflow exposure. Therefore, the fluctuation mode is considered suitable for long-duration use. Moreover, field measurements in an actual office showed that the fluctuation mode was superior in terms of both comfort and energy saving compared with conventional air conditioning.

scholarly journals Overview of and First Observations from the TILDAE High-Altitude Balloon Mission

2017 ◽  
Author(s):  
Bennett A. Maruca ◽  
Raffaele Marino ◽  
David Sundkvist ◽  
Niharika H. Godbole ◽  
Stephane Constantin ◽  
...  
Keyword(s):  
Sonic Anemometer ◽  
Ambient Air ◽  
Small Scale ◽  
New Paradigm ◽  
Intermittent Turbulence ◽  
Atmospheric Measurements ◽  
Long Duration ◽  
In Situ Observations ◽  
Robust Separation

Abstract. Though the presence of intermittent turbulence in the stratosphere has been well established, much remains unknown about it. In-situ observations of this phenomenon, which have provided the greatest detail of it, have mostly been achieved via sounding balloons (i.e., small balloons which burst at peak altitude) carrying constant-temperature hot wire anemometers (CTA's). The Turbulence and Intermittency Long-Duration Atmospheric Experiment (TILDAE) was developed to test a new paradigm for stratospheric observations. Rather than flying on a sounding balloon, TILDAE was incorporated as an add-on experiment to the payload of a NASA long-duration balloon mission that launched in January, 2016 from McMurdo Station, Antarctica. Furthermore, TILDAE's key instrument was a sonic anemometer, which (relative to a CTA) provides better-calibrated measurements of wind velocity and a more-robust separation of velocity components. During the balloon's ascent, TILDAE's sonic anemometer provided atmospheric measurements up to an altitude of about 18 km, beyond which the ambient air pressure was too low for the instrument to function properly. Efforts are currently underway to scientifically analyze these observations of small-scale fluctuations in the troposphere, tropopause, and stratosphere and to develop strategies for increasing the maximum operating altitude of the sonic anemometer.

The LDE-Type Flare Occurrence (1969-1993)

1994 ◽  
Vol 144 ◽  
pp. 279-282
Author(s):  
A. Antalová
Keyword(s):  
Time Series ◽  
Fourier Analysis ◽  
Sunspot Cycle ◽  
List Type ◽  
Type Number ◽  
Solar Cycles ◽  
Type Iv ◽  
Long Duration ◽  
Cycle Maximum ◽  
Flare Index

AbstractThe occurrence of LDE-type flares in the last three cycles has been investigated. The Fourier analysis spectrum was calculated for the time series of the LDE-type flare occurrence during the 20-th, the 21-st and the rising part of the 22-nd cycle. LDE-type flares (Long Duration Events in SXR) are associated with the interplanetary protons (SEP and STIP as well), energized coronal archs and radio type IV emission. Generally, in all the cycles considered, LDE-type flares mainly originated during a 6-year interval of the respective cycle (2 years before and 4 years after the sunspot cycle maximum). The following significant periodicities were found:• in the 20-th cycle: 1.4, 2.1, 2.9, 4.0, 10.7 and 54.2 of month,• in the 21-st cycle: 1.2, 1.6, 2.8, 4.9, 7.8 and 44.5 of month,• in the 22-nd cycle, till March 1992: 1.4, 1.8, 2.4, 7.2, 8.7, 11.8 and 29.1 of month,• in all interval (1969-1992):a)the longer periodicities: 232.1, 121.1 (the dominant at 10.1 of year), 80.7, 61.9 and 25.6 of month,b)the shorter periodicities: 4.7, 5.0, 6.8, 7.9, 9.1, 15.8 and 20.4 of month.Fourier analysis of the LDE-type flare index (FI) yields significant peaks at 2.3 - 2.9 months and 4.2 - 4.9 months. These short periodicities correspond remarkably in the all three last solar cycles. The larger periodicities are different in respective cycles.

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