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Atmospheric Research Instrumentation The most comprehensive range for monitoring radiative forcing components

N2O

H2O Vapour

CH4 Aerosols

03

CO2


Atmospheric Aerosols

Anthropogenic aerosols have the largest uncertainty factor, and are the least understood, amongst all radiative forcing components. Aerosols in the atmosphere influence the radiative balance through direct scattering of solar radiation, and indirect effects in the formation of clouds and precipitation. The measurement of back and angular scattering from aerosols provide indepth analysis of their optical properties and their effect on the global energy balance.

Ecotech, through its collaboration with globally renowned atmospheric research institutions, now provide the scientific community with the most advanced commercially available nephelometers ever seen. Our Aurora nephelometers range from the standard 3 wavelength with backscatter, through to our polar nephelometer and now our total humidity control system.


Atmospheric Aerosols Aurora Nephelometer The catalyst for creating the next generation of nephelometers started with the release of a paper by Müller et al (2009). This paper highlighted the limitations of our original light source. The new design incorporates both an opal glass diffuser and high intensity LED’s, providing a significantly improved lambertian distribution (Müller et al 2010), as demonstrated in figure 1. Müller, T., Nowak, A., Wiedensohler, A., Sheridan, P., Laborde, M., Covert, David S., Marinoni, Angela, Imre, Kornelia, Henzing, Bas, Roger, JeanClaude, dos Santos, Sebastiao Martins, Wilhelm, Reinhard, Wang, Ya-Qiang and de Leeuw, Gerrit (2009) ‘Angular Illumination and Truncation of Three Different Integrating Nephelometers: Implications for Empirical, Size-Based Corrections’, Aerosol Science and Technology, 43:6, 581-586 Müller, T., Laborde, M., Kassell, G., and Wiedensohler, A. (2010): Design and performance of a three wavelength LED-based total scatter and backscatter integrating nephelometer, Atmos. Meas. Tech. Discuss., 3, 4835–4864, doi:10.5194/amtd-3-4835-2010, 2010.

Aurora benefits

LED vs Flash Lamp

3  year warranty on light source, guaranteed not to fail

Ecotech’s patented LED light source (U.S. Patent Office 7, 671, 988) has a number of advantages over the traditional flash lamp light source.

M  ost affordable research grade nephelometer on the market

• An LED light source is guaranteed not to fail within 3 years and often exceeds 5 years compared to a flash lamp that is recommended to be changed every 4-6 months

C  an be deployed in high altitude within an aircraft U  nique in its simplicity and practicality F  ully integrated package including; internal sample pump, RH control, internal calibration valves and data logging O  ptional 12 VDC operation (60 max/15 watts)

• Heat generated by the LED light source is a fraction of that generated by a flash lamp, minimizing changes in sample RH • LED’s emit light at a specific wavelength (525nm, 450nm, 635nm) eliminating the need for band pass filters • An LED light source uses the same light path for each wavelength which

o Ensures consistency between the different light paths

o Requires only one PMT instead of three

o Maximises light intensity with no splitting of the light into 3 separate paths


Figure 1: Lambertian distribution with backscatter

Figure 2: Light source with backscatter shutter

Opal Glass Light Source

Backscatter

Ecotech combine high powered LED’s with an opal glass diffuser to produce a lambertian distribution at 3 specific wavelengths (525nm, 450nm and 635nm). The truncation angle of this light source ranges from 9° to 170°.

The backscatter feature of the Aurora nephelometers is achieved through the use of a shutter mounted on the light source inside the cell. This shutter moves periodically (every 1.5 seconds) between two locations in and out of the optical path of the light source. During backscatter measurements the Lambertian distribution of the light source is limited to 90° to 170°.

Figure 3: Lambertian distribution of polar light source

Figure 4: Changes in light scattering with humidity

Polar Nephelometry

Total Humidity Control

Traditional backscatter measurements only provide data on total scatter and backscatter.

Changes in humidity are known to drastically affect the light scattering properties of hygroscopic aerosols. Controlling humidity within a sample allows measurement of the impact humidity has on the light scattering properties of aerosols from 40% to 95% humidity.

Ecotech’s polar nephelometer provides more specific light scattering measurements from any angle between 10° and 90° up to 170°, with up to 18 different angles per measurement. This extra measurement provides comprehensive data allowing a greater characterization of aerosol scattering than the basic backscatter.

Two nephelometers in parallel, simultaneously measure the same sample in real time, with humidity controlled independently within each sample. The humidity of one sample can be fixed whilst the other sample’s humidity is changed to determine the scattering enhancement factor.


Greenhouse Gases Greenhouse gas emissions are the major anthropogenic agents inducing changes in the global radiation balance. Policy decisions made on climate change research demand precise, highly accurate and repeatable data for all greenhouse gases, not just CO2. Additional greenhouse gases such as CH4 and N2O, along with water vapour, have a major influence on radiative forcings. Measurement of CO, due to its impact on greenhouse gases, is also an important factor for any comprehensive global radiation balance study. Partnering with the University of Wollongong, Ecotech has developed the most comprehensive greenhouse gas analyser on the market. Named the Spectronus, for its detailed analysis of the IR spectrum, it offers continuous and simultaneous measurements of all principle greenhouse gases combined within a single instrument.


Greenhouse Gases Spectronus Gas Analyser The multi-species capability of the Spectronus allows holistic greenhouse gas studies which probe the whole picture. Simultaneous measurement of all gases in the same air sample allow correlations and relationships to be identified between greenhouse gases in a way impossible with multiple analysers. The Spectronus measures CO2, CH4, N2O and CO simultaneously with precision exceeding GAW requirements as well as δ13C in CO2 with precision below 0.1‰

Spectronus Benefits

Powerful Software

M  easures major greenhouse gases and selected isotopologues

The Spectronus operating software is a flexible, fully automated system allowing:

M  easured spectra are saved allowing for optional re-analyses for improving measurement if desired

• Full spectrum measurement and analysis

L  ong term stability without frequent calibration R  apid real time measurement at mid IR wavelengths

• Sequencing of measurements from multiple inlets or tank gases • Continuous logging of data in real-time • Remote access and operation of instrument Detailed analysis of trace gas concentrations are determined by quantitative spectrum analysis using a powerful, non-linear, least squares fitting algorithm based on the MALT5 program (Griffith 1996) (Griffith, D. W. T. (1996), Synthetic calibration and quantitative analysis of gas phase infrared spectra, Appl. Spectrosc., 50(1), 59-70.)


Figure 5: Allan-Variance plot of N2O

Figure 6: Allan-Variance plot of CO2

N20

CO2

Greenhouse gas research has focused around CO2 and CH4. The Spectronus combines analysis of these gases with high repeatability and excellent reproducibility of N2O.   With a radiative forcing 310 times more than CO2 and a long atmospheric lifetime (approx 120 years) (Solomon et al 2007), it is an important field of greenhouse gas research.

The importance of CO2 on the global radiation balance lies in the understanding of the comparison of 12C to 13C. Burning of coal, petroleum and oil releases 12C in the ambient air, thus the source of the CO2 can be identified. Concentrations in fires change rapidly, and so the ability of the Spetronus to collect 1 second data, which can be reanalysed at a later time, is of great benefit.

Solomon, S., et al. (2007), Climate Change 2007: The physical science basis. Contribution of Working Group 1 of the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Cambridge University Press, Cambridge.

Figure 7: Allan-Variance plot of CH4

Figure 8: Allan-Variance plot of CO

CH4

CO

Methane, along with CO2 , is one of the most influential greenhouse gases. Produced from a variety of sources such as livestock, natural gas and anaerobic bacteria, it is an essential gas to be monitored.  The above Allan Variance plot shows the precision and stability of the Spectronus CH4 measurement.

Carbon monoxide has a strong IR absorption but is short lived in the atmosphere. Its reaction with tropospheric ozone, makes it a major contributor to the radiation balance.  Spectronus FTIR technology provides high accuracy CO data simultaneously with N2O, CO2 and CH4 data from the same air sample allowing for a complete multi-parameter analysis.


Spectronus Specifications Species

1-σ precision - (5 min avg)

GAW required accuracy

0.05

0.1 (0.05 SH)

CH4 nmol mol-1

0.2

2.0

N2O nmol mol

<0.06

0.1

CO nmol mol

0.2

2.0

δ13C-CO2 / ‰

<0.08

0.01

δD in H2O vapour / ‰

1

NA

δ O in H2O vapour / ‰

0.2

NA

CO2 µmol mol

-1

-1

-1

18

Applications • Continuous monitoring of air and other gas mixtures from one or more sample inlets • Vertical profiles of trace gases (including water and CO2 isotopes) collected from inlets at various heights on a mast or tower (micrometeorological flux gradient measurements) • Soil trace gas flux measurements using automated soil-cover chambers • Automated batch analysis of flask or bag air samples • Propagation of reference tank gas standards (when used as comparator)

Aurora Nephelometer Specifications Specifications Ranges

0.0 to > 20 000Mm-1

LDL

<0.3 Mm-1 Full Scatter (60 sec average) <0.1 Mm-1 Total Scatter (60 sec average)

Sample Flow Range

5 l/min approx

Weight

11.2 kg

Wavelength

525nm, 450nm and 635nm

Intensity function

9-170°

Polar Sectors

User customisable up to 17 sectors

Applications • Aerosol scattering and backscatter • Scattering enhancement factor • Ångström exponent • Determination of single scattering albedo

For more information on Ecotech please visit:

www.ecotech.com Email info@ecotech.com

Ecotech Atmospheric Research Instrumentation  

The most comprehensive range formonitoring radiative forcing components

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