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Aircraft > Specifications  
   
Twin Otter (Baylor/TNRCC)  
   

Endurance: 3.5-4 hrs

Ceiling: 2.5 km

Payload: 3200 lbs

Research Speed: 150

   

de Havilland Twin Otter DHC-6 Instrument Platform

A de Havilland Twin Otter DHC-6 Twin Otter as depicted in Figure 1, has been fitted with inlets and instrument racks for the sampling program. The aircraft has been inspected and certified by the Federal Aviation Administration (FAA) to operate in the Restricted category during air pollution sampling missions.

 

Parameter

Time Resolution

Method

Det. Limit

Ozone (O3)

5 second poll of

10 second updates

Ultra Violet (UV) Photometry/Absorption

 

 3 ppb

Ozone (O3)

1 second poll of 2 second updates

Sample reacted in a constant concentration nitric oxide (NO) gas stream, (i.e. NO titration), and Chemiluminescence

 3 ppb

Sulfur Dioxide (SO2)

1 second poll of

2 second updates

UV Pulsed  Fluorescence

 

 1 ppb

Nitrogen Oxide (NO)

1 second poll of

2 second updates

Chemiluminescence

 

 2 ppb

Total Reactive Oxides of Nitrogen (NOy)

1 second poll of

2 second updates

Molybdenum (Mo) calalytic sample reduction at 320 oC and Chemiluminescence

 

 2 ppb

Total Nitrates

(i.e. Nitric acid plus particulate and/or aerosol nitrates)

 

1 second poll of

2 second updates

Nylasorb filter then molybdenum (Mo) catalytic sample reduction at 320 oC and Chemiluminescence. The resulting measurement, NOy*, (i.e. NOy less the nitric acid and particulate/ aerosol nitrates) is subtracted from the NOy measurement result.  The difference equals the total nitrates.

 

 2 ppb

Nitrogen Dioxide (NO2)

1 second poll of

2 second updates

UV Photolysis with Chemiluminescence

 

 2 ppb

Carbon Monoxide (CO)

1 second poll of

1 second updates

Vacuum Ultra Violet, (VUV) Fluorescence

 

2 ppb

 

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Light scattering               (red, green and blue wavelengths)                  (particle scattering (bsp) and backscatter)

 

5 seconds

 

Integrating  Nephelometer

1 * 10 x e-6 m-1

Particle Sulfate (SO4)

 

Semi-continuous

 2 minute updates

 Flash Volatilization            

5 ug/m3

Particulate matter less than 2.5 microns  in diameter (PM 2.5)

 

Mass

 

* Elements

 (38-40 see list)

 

Sulfate: SO42-  

Nitrate : NO3-

Chloride: Cl-

 

discrete filter

(47 mm Teflon and

37 mm Quartz)

URG Filter Pack

 

 

Gravimetry

 

X-Ray Fluorescence

 

 

Ion Chromatography

Ion Chromatography

Ion Chromatography

 

 

 

15 ug/filter

 

0.01B 0.86

ug/filter

 

1.5 ug/filter

1.5 ug/filter

1.5 ug/filter

Volatile Organic Compounds (VOC)

discrete grab in

SS canister

TNRCC OAL Gas Chromatography/Mass Selective Detector (MSD)   

 

0.2 ppbv

Volatile Organic Compounds (VOC)

discrete grab in

SS canister

On-Site Gas Chromatography/Mass Spectroscopy      

10 pptv

Altitude 

5 seconds

 

Barometric Pressure

Transducer

1 hPa

Latitude and Longitude

5 seconds

 

Global Positioning System (GPS) Garmin Model 150 Interfaced to the Air Data Computer

0.04 seconds of Latitude and/or Longitude

Wind Direction

5 seconds

Shadin ADC 200

5 Degrees

Wind Speed

5 seconds

Shadin ADC 200

5 Knots

(5.76 mph)

Outside (Ambient) Air Temperature

5 seconds

Type AT@ Thermocouple

0.01 Degrees Celsius

Cabin Air Temperature

5 seconds

Type AT@ Thermocouple

 

0.01 Degrees Celsius

Dew Point

5 seconds

Chilled mirror optical hygrometer

(Buck Model 1101B)

 

0.001 Degrees Celsius

Relative Humidity

5 seconds

From the inlet of the TSI 3 wave Nephelometer

0.1%

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