BOREAS AFM-04 Twin Otter Aircraft Sounding Data

Summary

The BOREAS AFM-04 team used the NRC Twin Otter aircraft to make sounding 
measurements through the boundary layer.  These measurements included 
concentrations of carbon dioxide and ozone, atmospheric pressure, dry bulb 
temperature, potential temperature, dewpoint temperature, calculated mixing 
ratio, and wind speed and direction.  Aircraft position, heading, and altitude 
were also recorded.  Data were collected at both the NSA and the SSA in 1994 and 
1996.  These data are stored in tabular ASCII files.

Table of Contents

   *  1 Data Set Overview
   *  2 Investigator(s)
   *  3 Theory of Measurements
   *  4 Equipment
   *  5 Data Acquisition Methods
   *  6 Observations
   *  7 Data Description
   *  8 Data Organization
   *  9 Data Manipulations
   *  10 Errors
   *  11 Notes
   *  12 Application of the Data Set
   *  13 Future Modifications and Plans
   *  14 Software
   *  15 Data Access
   *  16 Output Products and Availability
   *  17 References
   *  18 Glossary of Terms
   *  19 List of Acronyms
   *  20 Document Information

1. Data Set Overview

1.1 Data Set Identification

BOREAS AFM-04 Twin Otter Aircraft Sounding Data

1.2 Data Set Introduction

The BOReal Ecosystem-Atmosphere Study (BOREAS) Airborne Fluxes and Meteorology 
(AFM)-04 team used the National Research Council (NRC) Twin Otter aircraft to 
make sounding measurements through the boundary layer.  These measurements 
included concentrations of carbon dioxide and ozone, atmospheric pressure, dry 
bulb temperature, potential temperature, dewpoint temperature, calculated mixing 
ratio, and wind speed and direction.  Aircraft position, heading, and altitude 
were also recorded.  Data were collected at both the Northern Study Area (NSA) 
and Southern Study Area (SSA) in 1994 and 1996.  These data are stored in 
tabular American Standard Code for Information Interchange (ASCII) files.

1.3 Objective/Purpose

The Twin Otter was one of four flux aircraft operated in BOREAS.  The purpose of 
its sounding flights was to make measurements through the boundary layer to 
document the vertical structure of the atmosphere over the test area 
(MacPherson, 1996; MacPherson and Bastian, 1997).  The mixed layer was of 
particular interest in this research.

1.4 Summary of Parameters

Atmospheric Pressure, Orthogonal Components of the Wind Velocity, Wind Speed and 
Direction, Dry Bulb Temperature, Potential Temperature, Dewpoint Temperature, 
Calculated Mixing Ratio, Carbon Dioxide Concentration, Ozone Concentration, 
Aircraft Position, Heading, Altitude (Radar and Pressure).

1.5 Discussion

The Twin Otter operated in all three Intensive Field Campaigns (IFCs) in 1994 
and in July and August 1996. The archived data were collected on sounding runs 
over the BOREAS site from near the surface to between 6,000 and 8,000 ft (2 and 
2.5 km).  The Twin Otter flew 51 sounding flights in 1994 and 26 flights in 
1996.

1.6 Related Data Sets

BOREAS AFM-01 NOAA/ATDD Long-EZ 1994 Aircraft Flux Data over the SSA
BOREAS AFM-02 Wyoming King Air 1994 Aircraft Flux and Moving Window Data
BOREAS AFM-02 Wyoming King Air 1994 Aircraft Sounding Data
BOREAS AFM-03 NCAR Electra 1994 Aircraft Flux Data
BOREAS AFM-03 NCAR Electra 1994 Aircraft Moving Window Data
BOREAS AFM-03 NCAR Electra 1994 Aircraft Sounding Data
BOREAS AFM-04 NRC Twin Otter Aircraft Flux Data
BOREAS AFM-04 NRC Twin Otter Aircraft Sounding Data
BOREAS AFM-05 Level-1 Upper Air Network Data
BOREAS AFM-05 Level-2 Upper Air Network Standard Pressure Level Data

2. Investigator(s)

2.1 Investigator(s) Name and Title

J. Ian MacPherson
Flight Research Laboratory
Institute for Aerospace Research
National Research Council of Canada
Ottawa, Ontario Canada 

Raymond L. Desjardins
Centre for Land and Biological Resources Research
Agriculture Canada
Central Experimental Farm
Ottawa, Ontario, Canada 

2.2 Title of Investigation

Atmospheric Boundary Layer Analyses from Canadian Twin Otter Aircraft 

2.3 Contact Information

Contact 1
----------
J. Ian MacPherson 
National Research Council
Ottawa, Ontario 
Canada 
(613) 998-3014 
(613) 952-1704 (fax) 
jim@u614ji.iar.nrc.ca 

Contact 2
----------
David Knapp
Raytheon ITSS
NASA GSFC
Greenbelt, MD
(301) 286-1424
(301) 286-0239 (fax)
David.Knapp@gsfc.nasa.gov

3. Theory of Measurements

A series of reports addressing the theory and practice of measuring atmospheric 
variables from a moving, aircraft platform may be found in MacPherson (1988, 
1990a, 1990b, 1992, 1996), MacPherson and Morgan (1981), and MacPherson and 
Bastian (1997).

A basic requirement for measuring gas fluxes from a moving aircraft is to 
account for the motion of the air relative to the motion of the aircraft.  The 
true air motion is derived from the vector difference between the air velocity 
relative to the aircraft velocity relative to the ground.

Air motion relative to the aircraft is measured by a nose-mounted gust boom 
incorporating a Rosemount 858AJ28 5-hole probe.  This device and the associated 
pressure transducers measure static pressure (altitude), dynamic pressure 
(airspeed), and the angles of attack and sideslip.  These instruments in 
combination with a global positioning system (GPS) and an inertial reference 
system (IRS) are used to derive the flux measurements. 

4. Equipment

4.1 Sensor/Instrument Description

The Twin Otter atmospheric research aircraft is a highly instrumented platform 
for research on the atmospheric boundary layer, air pollution, etc.  
Descriptions of the aircraft and its instrumentation and software are given in 
detail in MacPherson (1988, 1990a, 1990b, 1996), MacPherson and Morgan (1981), 
and MacPherson and Bastian (1997).

The instruments used to make these measurements included:

Parameter              Instrument
Sensible Heat         Rosemount fast response 102DJ1CG
Incident Solar Rad.   Kipp and Zonen CM-11 pyranometer (305-2800 nm range)
Reflected Solar Rad.  Eppley pyranometer
Greenness Index       Skye Industries Vegetation Greenness Indicator
Surface Temperature   Barnes PRT-5 infrared radiometer
Satellite Simulation  Exotech 100BX Satellite Simulator
CO2, H2O               LI-COR LI-6262 CO2/H2O analyzer (these CO2 data reported to
                      BORIS)
                      ESRI (developed by Agriculture Canada)
Dewpoint              E, G, and G Model 137-S10 Cambridge dewpoint sensor
Ozone                 TECO Ozone Analyzer Model 49 (these O3 data reported to
                      the BOREAS Information System (BORIS))
                      GFAS (unit borrowed from German Aerospace Research
                      Establishment)
                      Scintrex LOZ-3 ozone detector
Momentum              Wind Components
Inertial Velocity     Litton LTN-90-100 IRS
Position              Trimble Model TNL-7880SR GPS/VLF/Omega
Altitude (AGL)        Sperry AA-200 Radio Altimeter (1994 and 1996)
                      Riegl LD-90-3 Laser Altimeter (1996 only)

4.1.1 Collection Environment

The data were collected from the aircraft, flying from near the surface to 
between 6,000 and 8,000 ft (2 and 2.5 km).

4.1.2 Source/Platform

Twin Otter DHC-6-200 twin turboprop utility transport. 

The maximum gross takeoff weight is 11,579 lb. The service ceiling is 20,000 ft. 
The endurance is 3 to 4 hours, depending on instrumentation and weather. 

4.1.3 Source/Platform Mission Objectives

The primary objective was to make measurements through the boundary layer to 
document the vertical structure of the atmosphere over the test area 
(MacPherson, 1996; MacPherson and Bastian, 1997).  The mixed layer was of 
particular interest in this research.

4.1.4 Key Variables

Atmospheric Pressure, Orthogonal Components of the Wind Velocity, Wind Speed and 
Direction, Dry Bulb Temperature, Potential Temperature, Dewpoint Temperature, 
Calculated Mixing Ratio, Carbon Dioxide Concentration, Ozone Concentration, 
Aircraft Position, Heading, Altitude (Radar and Pressure).

4.1.5 Principles of Operation

The principles of operation of the aircraft and its instrumentation and software 
are given in detail in MacPherson (1988, 1990a, 1990b, 1996), MacPherson and 
Morgan (1981), and MacPherson and Bastian (1997).

4.1.6 Sensor/Instrument Measurement Geometry

See MacPherson (1988, 1990a, 1990b, 1996) and MacPherson and Bastian (1997).

4.1.7 Manufacturer of Sensor/Instrument

See Sections 4.1 and 6, MacPherson (1996), and MacPherson and Bastian (1997).

4.2 Calibration

Instruments on the aircraft were calibrated prior to each IFC.  Key instruments 
(such as temperature probes) were calibrated two or three times during each IFC. 

4.2.1 Specifications

Not available at this revision.

4.2.1.1 Tolerance

Not available at this revision.

4.2.2 Frequency of Calibration

All instruments were calibrated at least once per IFC.

4.2.3 Other Calibration Information

See MacPherson (1988, 1990a, 1990b, 1996) and MacPherson and Bastian (1997).

5. Data Acquisition Methods

The data were collected from the aircraft, flying from near the surface to 
between 6,000 and 8,000 ft (2 and 2.5 km) in a spiral pattern.  

6. Observations

6.1 Data Notes

The following is a table that describes how the data were recorded.

Note: 128 channels of data are recorded digitally in 16-bit words at 16 
samples per second (1994) or 32 samples per second (1996) on a digital archive 
tape (DAT) drive.  Signals are low-pass filtered with a breakpoint of 5 Hz to 
prevent aliasing. 

The following table lists the 128 recorded signals.  Not all of these are 
archived to BORIS (see Section 8), but many contribute to calculated quantities 
such as true airspeed (TAS), wind velocity, and fluxes. 

**Note:***  This is basically the recorder buffer to be used in the BOREAS site 
visit in May 1993.  Additional parameters were recorded in BOREAS (e.g., 
satellite simulator).  A Trimble GPS replaced or augmented the Loran-C in 1994.

Channel Number Variable Name Units  Recorded   Instrument   Description 
Resolution (per bit)
__________________________________________________________________________ 
  1 FILEHR HRS 1 NAE CLOCK COMBINED WORD, TAPE FILE AND GMT HOURS. 
  2 MINSEC  MIN/SEC      1      NAE CLOCK             COMBINED WORD, 
    GMT MINUTES/ SECONDS. 
  3 EVENT       -        1      EVENT MARKER         MULTI LEVEL 
    EVENT MARKER 
  4 LTD DEG 1 ARNAV LORAN-C | LATITUDE DEGREES 
  5 LTM MIN 0.01 MODEL 40-AVA-100 | LATITUDE MINUTES 
  6 LGD DEG 1 "" | LONGITUDE DEGREES 
  7 LGM MIN 0.01 "" | LONGITUDE MINUTES 
  8 LTML MIN 0.01 LITTON INERTIAL REF | LATITUDE MINUTES 
  9 LGML MIN 0.01 SYSTEM, LTN-90-100 | LONGITUDE MINUTES 
 10 HDGT DEG 0.1 SPERRY C-12 GYRO TRUE HEADING 
    (MAGNETIC HEADING CORRECTED TO TRUE HEADING USING MAG VARIATION OUTPUT   
    FROM LORAN-C) 
 11 HDGTL        DEC      0.1     LITTON 90 IRS      TRUE HEADING, LITTON  
 12 WDTI           DEG      0.1      * DERIVED*        WIND DIRECTION     FROM
    DOPPLER/ INERTIAL SYSTEM, DEGREES TRUE ( NOTE 1) 
 13 WDTL      DEG      0.1      * DERIVED*          FROM LITTON SYSTEM 
    (SEE NOTE 2) 
 14 WSMI M/S 0.01 * DERIVED* WIND SPEED FROM DOPPLER INERTIAL SYSTEM ( NOTE 1) 
 15 WSML      M/S     0.01      * DERIVED*          FROM LITTON SYSTEM 
    (SEE NOTE 2) 
 16 UGE M/S 0.01 * DERIVED* NORTH/SOUTH WIND COMPONENT FROM DOPPLER/INERTIAL 
     SYSTEM, + FROM N 
 17 VGE     M/S       0.0             * DERIVED*     EAST/WEST, + FROM EAST 
 18 WGE     M/S       0.0             * DERIVED*     VERTICAL WIND, + UP  19 LWN 
     M/S       0.0             * DERIVED*
     NORTH/SOUTH WIND COMPONENT FROM LITTON SYSTEM, (NOTE 2), + FROM N 
 20 LWE     M/S       0.01            * DERIVED*          EAST/WEST WIND 
    COMPONENT, + FROM E 
 21 WEP     M/S       0.01            * DERIVED* VERTICAL WIND COMPONENT 
 22 TSNBC DEG C 0.01 * DERIVED* STATIC TEMPERATURE, DERIVED FROM TAS &
    TOTAL TEMP (SEE CH 48) NOSE STARBOARD TEMPERATURE PROBE 
 23 DEWPTC     DEG C   0.01     EGG MODEL 137          DEW POINT 
 24 SDCTC      DEG C   0.01      * DERIVED*       STATIC TEMPERATURE 
    IN C02 ANALYZER DUCT, DERIVED FROM DUCT TAS & DUCT TOTAL TEMP; ROSEMOUNT
    102 PROBE 
 25 PRT5C         DEG C   0.01      BARNES PRT-5         SURFACE TEMPERATURE 
 26 RADUP        W/M2     0.1       KIPP & ZONEN CM-11   UPWARD FACING 
    RADIOMETER, MEASURES INCIDENT RADIATION (SEE ALSO NOTE 3) 
 27 RADOWN    W/M2     0.1     EPPLEY PYRANOMETER-2 DOWNWARD FACING 
    RADIOMETER, MEASURES REFLECTED RADIATION. 
 28 C02N02    MG/M3    0.1     AGRICULTURE CANADA    CARBON DIOXIDE CONC 
    ESRI C02/H20 ANALYZER 20 HZ RESPONSE, LOW PASS FILTERED AT 5.5 HZ FOR 
    ANTI-ALIASING 
 29 H20       G/M3            0.01      C02/H20 ANALYZER     WATER VAPOR 
    CONC, ESRI 
 30 RALT       M  0.1         SPERRY AA-200 RADIO  HEIGHT ABOVE GROUND 
    ALTIMETER 
 31 TASFK KTS 0.1 * DERIVED* TRUE AIRSPEED, FUSELAGE PROBES. 
 32 TASNBK KTS 0.1 * DERIVED* TRUE AIRSPEED, NOSEBOOM PROBES. 
 33 TASDCT KTS 0.1 * DERIVED* TRUE AIRSPEED IN C02/H20 ANALYZER DUCT. 
 34 PSDUCT     MB      0.1     A.I.R. AIR-DB-2C    STATIC PRESSURE IN DUCT. 
 35 PSNBC MB 0.1 PAROSCIENTIFIC STATIC PRESSURE 215L-AW-012     NOSEBOOM, 
    CORRECTED FOR POSITION ERROR 
 36 TSFC    DEG C     0.01      * DERIVED*         STATIC TEMPERATURE, 
    DERIVED FROM TAS AND TOTAL TEMP MEASURED BY FUSELAGE PORT ROSEMOUNT PROBE 
    (SEE CHANNEL 47) 
 37 GRNRAT      -    0.001     SKYE INDUSTRIES    GREENNESS RATIO, 730 
    SKR-100            NM SIGNAL/660 NM SIGNAL. 
 38 VDTM      M/S      0.1     DECCA DOPPLER      GROUND SPEED, TOTAL 
    RADAR-72         VECTOR FROM DOPPLER RADAR. 
 39 GSL       KTS      0.1     LITTON 90 IRS      GROUND SPEED, TOTAL 
    VECTOR FROM LITTON 
 40 LCC02 MV 1.0 LICOR 6262 C02 CONCENTRATION, RECORDED AS MILLIVOLTS,
    CONVERTED TO PPM 
 41 LCTSC    DEG C    0.01     LICOR 6262         TEMPERATURE IN LICOR 
    ANALYZER TEST CELL 
 42 UGEIL M/S 0.01 * DERIVED* NORTH/SOUTH WIND COMPONENT FROM DOPPLER/LITTON
    SYSTEM, + FROM N. 
 43 VGEIL          M/S      0.01        * DERIVED*     EAST/WEST, + FROM E. 
 44 WGEIL         M/S      0.01        * DERIVED*     VERTICAL WIND, + UP 
 45 LCH20     MV       1.0      LICOR 6262          H20 CONCENTRATION 
    RECORED AS MILLIVOLTS, CONVERTED TO PPT 
 46 WFIL      M/S     0.01      *DERIVED*         HIGH-PASS FILTERED 
    VERTICAL WIND FOR EDDY ACCUMULATION SYSTEM 
 47 TTF      DEG K    0.01     ROSEMOUNT 102DJ1CG   TOTAL TEMPERATURE, 
    FAST RESPONSE, PORT FUSELAGE PROBE 
 48 TTNB     DEG K    0.01     ROSEMOUNT 102DJ1CG   TOTAL TEMPERATURE, 
    FAST RESPONSE, STAR'B FUSELAGE PROBE 
 49 PSFC      MB       0.1     ROSEMOUNT 1201F1B4A1B  STATIC PRESSURE, 
    FUSELAGE PORTS, CORRECTED FOR POSITION ERROR. 
 50 METHAN    PPB      1.0     UNISEARCH TDL         METHANE CONCENTRATION 
    METHANE ANALYZER 
 51 -- --- NOT USED 
 52 TECO PPB 0.1 TECO-49 OZONE CONCENTRATION ANALYZER SLOW RESPONSE FOR 
    MEAN CONCENTRATIONS 
 53 OZD       PPB      0.1     GERMAN OZONE ANALYZER  OZONE CONCENTRATION 
    GFAS OS-G-2 FAST RESPONSE (>10 HZ) 
 54 DOZD PPB 0.01 "" HI-SENSITIVITY OZONE FLUCTUATIONS FROM START OF FLUX RUN 
 55 UCO2N2   MG/M3    0.1     AGRICULTURE CANADA     RAW C02 UNFILTERED
    SIGNAL C02/H20 ANALYZER 
 56 UH20N2 G/M3 0.01 AGRICULTURE CANADA RAW H20 UNFILTERED SIGNAL C02/H20
    ANALYZER 
 57 THETAL DEG 0.01 LITTON-90 IRS PITCH ATTITUDE + NOSE UP 
 58 PHIL DEG 0.01 LITTON-90 IRS ROLL ATTITUDE + RIGHT WING DOWN 
 59 VXMLTN M/S 1/128 DECCA DOPPLER RADAR-72 ALONG-HEADING COMPONENT OF GROUND
    SPEED, POSITIVE FORWARD. 
 60 VYMLTN    M/S    1/256    DECCA DOPPLER RADAR-72   ACROSS-HEADING 
    COMPONENT OF GROUND SPEED, POSITIVE STARBOARD 
 61 VZMLTN    M/S    1/512    DECCA DOPPLER RADAR-72  VERTICAL COMPONENT 
    OF AIRCRAFT VELOCITY REL TO GROUND, + DOWN. (ABOVE 3 CORRECTED TO POSITION
    OF LITTON-90 IRS). 
 62 ULN       M/S     0.01    LITTON-90 IRS         NORTH/SOUTH INERTIAL 
    VELOCITY, + TO NORTH. 
 63 VLE      M/S     0.0         LITTON-90 IRS EAST/WEST, + TO EAST 
 64 WZL      M/S     0.0         LITTON-90 IRS  VERTICAL, + DOWN 
 65 PDF      MB      0.01        ROSEMOUNT TRANSDUCER    DYNAMIC PRESSURE 
    1221F-2VL7A1A  FUSELAGE PITOT UNCORRECTED FOR P.E. 
 66 PDNB      MB      0.01    ROSEMOUNT TRANSDUCER  DYNAMIC PRESSURE 
    1221F-1V7A1B   NOSEBOOM PITOT UNCORRECTED FOR P.E. 
 67 PSF       MB      0.10    ROSEMOUNT TRANSDUCER  STATIC PRESSURE, 
    1201F-1B4A1B    FUSELAGE PORTS, UNCORRECTED FOR P.E. 
 68 PSNBLR    MB      0.10    PAROSCIENTIFIC         STATIC PRESSURE 
    215L-AW-012     NOSEBOOM, CORRECTED TO LAB STANDARD, UNCORRECTED FOR P.E. 
 69 PD        MB      0.01    *DERIVED*             DYNAMIC PRESSURE USED 
    (PDNB OR PDF) IN REAL TIME SOFTWARE SELECTED BY FUNCTION SWITCH 
 70 PDFNB     MB      0.01    *DERIVED*             DYNAMIC PRESSURE FROM 
    FUSELAGE PORT CORRECTED TO NOSEBOOM POSITION, USED AS PDNB BACKUP 
 71 EACONT    BITS     1.0    *DERIVED*             SIGNAL THAT CONTROLS 
    EDDY ACCUMULATION SYSTEM,1000 WHEN WFIL IS UP -1000 WHEN WFIL IS DOWN ZERO
    IN DEAD ZONE 
 72 TS        DEGC    0.01	*DERIVED*             STATIC TEMP USED IN REAL
    (TSFC OR TSNBC)         TIME SOFTWARE, SELECTED BY FUNCTION SWITCH 
 73 GRN660 - 0.01 SKYE INDUSTRIES 660 NM SIGNAL FROM SKR-100 GREENNESS DEVICE 
 74 GRN730 - 0.01 SKYE INDUSTRIES 730 NM SIGNAL FROM SKR-100 GREENNESS DEVICE 
 75 TSPARO DEGF 0.01 PAROSCIENTIFIC TRANSDUCER TEMPERATURE 215L-AW-012
    USED TO CORRECT STATIC PRESSURE SIGNAL
 76 WGAI       M/S     0.01     *DERIVED*             VERTICAL WIND, DOPPLER 
    SYSTEM, A/C AXES 
 77 LALT FT 1.0 LITTON 90/100 IRS ABSOLUTE HEIGHT 
 78 PALT FT 1.0 *DERIVED* PRESSURE HEIGHT, USES PSNBC
 79 LTDL DEG 1.0 LITTON 90/100 IRS LITTON LATITUDE, DEG ONLY 
 80 LTDL DEG 1.0 "" LITTON LONGITUDE, DEG ONLY
 81 PDFC MB 0.01 ROSEMOUNT TRANSDUCER DYNAMIC PRESSURE 1221F-2VL7A1A
    FUSELAGE PITOT CORRECTED FOR P.E. 
 82 PDNBC       MB     0.01   ROSEMOUNT TRANSDUCER  DYNAMIC PRESSURE 
    1221F-1V7A1B   NOSEBOOM PITOT CORRECTED FOR P.E. 
 83 VX       KNOTS   0.10  DECCA DOPPLER RADAR-72  GROUND SPEED, X COMPONENT 
    A/C AXES, + FORWARD 
 84 VY KNOTS 0.10 "" GROUND SPEED, Y COMPONENT A/C AXES, + TO STARBOARD
 85 VX KNOTS 0.10 "" GROUND SPEED, Z COMPONENT A/C AXES, + DOWN 
 86 THETA DEG 0.01 KEARFOTT ATTITUDE PITCH ATTITUDE GYRO, T2109 + NOSE UP 
 87 PHI DEG 0.01 KEARFOTT ATTITUDE ROLL ATTITUDE GYRO, T2109 + RIGHT WIND DOWN 
 88 AZL M/S2 0.01 LITTON 90/100 IRS VERTICAL ACCELERATION, A/C AXES,+ A/C DOWN
 89 EAZL M/S2 0.01 "" VERTICAL ACCELERATION EARTH AXES, +A/C DOWN 
 90 UAIRN     M/S    1/128      *DERIVED*            NORTH COMPONENT OF TRUE 
    AIRSPEED (TAS) VECTOR 
 91 VAIRE M/S 1/128 *DERIVED* EAST COMPONENT OF TRUE AIRSPEED VECTOR 
 92 WAIRZ M/S 1/128 *DERIVED* VERTICAL COMPONENT OF TRUE AIRSPEED VECTOR,+ A/C
    DOWN 
 93 UAIR     M/S       1/128     *DERIVED*    X-AXIS TAS      COMPONENT 
 94 VAIR     M/S       1/128     *DERIVED*    Y-AXIS TAS      COMPONENT 
 95 WAIR     M/S       1/128     *DERIVED*    Z-AXIS TAS      COMPONENT 
 96 UANAE    M/S       1/128     *DERIVED*    X-AXIS TAS      COMPONENT,     
CORRECTED TO NAE ACCELEROMETER LOCATION
 97 VANAE     M/S    1/128      *DERIVED*            Y-AXIS TAS COMPONENT, 
    CORRECTED TO NAE ACCELEROMETER LOCATION
 98 WANAE     M/S    1/128      *DERIVED*            Z-AXIS TAS COMPONENT, 
    CORRECTED TO NAE ACCELEROMETER LOCATION
 99 UALTN     M/S    1/128      *DERIVED*            X-AXIS TAS COMPONENT, 
    CORRECTED TO LITTON IRS LOCATION 
100 VALTN     M/S    1/128      *DERIVED*            Y-AXIS TAS COMPONENT, 
    CORRECTED TO LITTON IRS LOCATION 
101 WALTN     M/S    1/128      *DERIVED*            Z-AXIS TAS COMPONENT, 
    CORRECTED TO LITTON IRS LOCATION 
102 UMIX7     M/S    1/128      *DERIVED*       X INERTIAL VELOCITY COMPONENT 
    FROM NAE/DOP SYSTEM 
103 VMIX7 M/S 1/128 *DERIVED* Y INERTIAL VELOCITY COMPONENT FROM NAE/DOP
    SYSTEM 
104 WMIX7 M/S 1/128 *DERIVED* Z INERTIAL VELOCITY COMPONENT FROM NAE/DOP
    SYSTEM 
105 PDDUCT MB 0.01 ROSEMOUNT TRANSDUCER DYNAMIC PRESSURE IN C02 1221F-2VL7A1A
    MEASUREMENT DUCT
 106 ALPHA    DEG      0.01     ROSEMOUNT 858AJ28      ANGLE OF ATTACK PROBE &
    12211F1VL5A1  MEASURED BY 5 TRANSDUCER   HOLE PROBE ON NOSEBOOM
 107 BETA     DEG      0.01     ROSEMOUNT 858AJ28        ANGLE OF SIDE-PROBE &
    12211F1VL5A1  SLIP MEASURED TRANSDUCER   BY 5 HOLE PROBE  ON NOSEBOOM.
 108 UDOTN    M/S2    1/128      *DERIVED*            DERIVATIVE OF X INERTIAL 
    VELOCITY FROM NAE/DOP SYSTEM 
109 VDOTN    M/S2    1/128      *DERIVED*            DERIVATIVE OF Y INERTIAL 
    VELOCITY FROM NAE/DOP SYSTEM 
110 WDOTN    M/S2    1/128      *DERIVED*            DERIVATIVE OF Z INERTIAL 
    VELOCITY FROM NAE/DOP SYSTEM 
111 UGAI      M/S     0.01       *DERIVED*         LONGITUDINAL WIND, DOPPLER 
    SYSTEM, A/C AXES 
112 VGAI M/S 0.01 *DERIVED* LATERAL WIND, DOPPLER SYSTEM, A/C AXES 
113 PALFNB MB 0.01 ROSEMOUNT TRANSDUCER DIFFERENTIAL PRESSURE 1221-1F1VL5A1
    R-858 ANGLE OF ATTACK PORTS
 114 UGAIL      M/S    0.01       *DERIVED*         LONGITUDINAL WIND, LIT/DOP
    SYSTEM, A/C AXES 
115 VGAIL M/S 0.01 *DERIVED* LATERAL WIND, LIT/DOP SYSTEM, A/C AXES 
116 WGAIL M/S 0.01 *DERIVED* VERTICAL WIND, LIT/DOP SYSTEM, A/C AXES 
117 AXL M/S2 0.01 LITTON 90/100 IRS LONGITUDINAL ACCELERATION, A/C AXES,
    + A/C FWD 
118 AYL M/S2 0.01 LITTON 90/100 IRS LATERAL ACCELERATION, A/C AXES, + A/C
    STARB
119 PBETNB MB 0.01 ROSEMOUNT TRANSDUCER DIFFERENTIAL PRESSURE 1221-1F1VL5A1
    R-858 ANGLE OF SIDESLIP PORTS 
120  AX       M/S2    0.01     SYSTRON DONNER 4211  LONGITUDINAL ACCELERATION,
    A/C AXES, BACKUP SYSTEM
121 AY M/S2 0.01 SYSTRON DONNER 4211 LATERAL ACCELERATION, A/C AXES 
122 AX M/S2 0.01 SYSTRON DONNER 4211 VERTICAL ACCELERATION, A/C AXES 
123 PRATEL DEG/S 0.01 LITTON 90/100 IRS ROLL RATE, + RIGHT WING D 
124 QRATEL DEG/S 0.01 "" PITCH RATE, + NOSE UP 
125 RRATEL DEG/S 0.01 "" YAW RATE, + NOSE RIGHT 
126 PRATE DEG/S 0.01 SMITHS GYROS 402-RGA ROLL RATE, + RIGHT WING D
127 QRATE DEG/S 0.01 "" PITCH RATE, + NOSE UP 
128 RRATE DEG/S 0.01 "" YAW RATE, + NOSE RIGHT
 --------------------------------------------------------------------------- 

NOTE 1:  This is the backup, or alternative, wind measuring system in case 
Litton 90/100 IRS should fail: calculation of wind components is described in 
reports referenced in Section 17.1.  The air velocity relative to the aircraft 
is measured by the TAS and noseboom angles of attack and sideslip.  The aircraft 
inertial velocity relative to Earth is measured in aircraft axes by a system 
incorporating complementary filtering in real time on the aircraft 
microprocessor.  A system of accelerometers and rate gyros provides the high-
frequency components to this filter; the decca 3-axis Doppler radar provides the 
low-frequency components.  The resulting calculated velocity components in A/C 
axes are subtracted from the TAS components to get the three components of winds 
in A/C axes.  These are then resolved into Earth axes using the pitch, roll, 
attitude, and aircraft heading to get uge, vge, and wge (channels 16-18). 

NOTE 2: The primary wind system uses a Litton 90/100 IRS to measure the aircraft 
inertial velocity components in three Earth axes.  The IRS is similar to an 
Inertial Navigation System (INS), but measures the velocities, accelerations, 
and rates in aircraft axes as well as Earth axes.  This is also used to derive 
wind given in channels 11, 13, 15, 19, 20, 21, 42, 43, and 44 above.  Numerous 
tests have been done to compare flux data derived with these two different wind 
measuring systems on the Twin Otter.  Some of this appears in Dobosy et al., 
1997.  These studies reveal that fluxes derived with the older Doppler-based 
system appear to be underestimated by 10-15 percent.  The Litton-based wind 
should be used whenever possible (channels 19, 20, 21, 13, and 15).

6.2 Field Notes

None.

7. Data Description

7.1 Spatial Characteristics

7.1.1 Spatial Coverage

The sounding flights were made centered over a specific point, flying in a 
spiral pattern, ascending in altitude.

The start and end points for each sounding flight were as follows:

                                START                    END
                        Latitude    Longitude    Latitude    Longitude
IFC-1:  25-May-1994     53.51883N   105.48317W   53.59817N   105.25850W
                        53.58183N   106.27834W   53.49650N   106.10700W    
        26-May-1994     53.51467N   105.48350W   53.62700N   105.10416W
                        53.78517N   104.82267W   53.67783N   105.06850W
        29-May-1994     53.51900N   105.48317W   53.65617N   105.38084W
        01-Jun-1994     53.60417N   106.29400W   53.51883N   106.13850W
        04-Jun-1994     53.62283N   105.20500W   53.76150N   104.87217W
                        53.63650N   106.20467W   53.52950N   106.06033W
        07-Jun-1994     55.80250N    98.38917W   55.84517N   98.47000W
        08-Jun-1994     55.79000N    98.41100W   55.88383N   98.82283W
                        55.94933N    98.39883W   55.89467N   98.14183W
        09-Jun-1994     55.84883N    98.41950W   55.80550N   98.03200W
        10-Jun-1994     55.79583N    98.41783W   55.77517N   98.56100W
        11-Jun-1994     55.79817N    97.87016W   55.83650N   98.09634W
                        55.87500N    98.37517W   55.84083N   98.32350W
        13-Jun-1994     55.95250N    98.39600W   55.93683N   98.24050W
                        55.82833N    98.32750W   55.83117N   98.45900W
IFC-2:  20-Jul-1994     53.52433N   105.48083W   53.59583N  105.28967W
        21-Jul-1994     53.53117N   105.47667W   53.62850N  105.22800W
                        53.52850N   105.47933W   53.71933N  105.32267W
        22-Jul-1994     53.63283N   106.18916W   53.54867N  105.91483W
        24-Jul-1994     53.52850N   105.47816W   53.62033N  105.23367W
                        53.52417N   105.48217W   53.69150N  105.42416W
        25-Jul-1994     53.52567N   105.48100W   53.61467N  105.17733W
                        53.39400N   105.99416W   53.53667N  106.30717W
        26-Jul-1994     53.52800N   105.48083W   53.63300N  105.19083W
        27-Jul-1994     53.52400N   105.48383W   53.54600N  105.75816W
        28-Jul-1994     55.93433N    98.43684W   55.86283N   98.08283W
        29-Jul-1994     55.80000N    97.86333W   55.85450N   98.20634W
        01-Aug-1994     55.78867N    98.41367W   55.94533N   98.94550W
        02-Aug-1994     55.91933N    98.67316W   55.79033N   98.27766W
        04-Aug-1994     55.79433N    98.39983W   55.81483N   98.34267W
        08-Aug-1994     55.90267N    98.31233W   55.92767N   98.24866W     
IFC-3:  31-Aug-1994     55.81317N    98.37100W   55.77517N   98.50450W
        02-Sep-1994     55.79716N    97.87117W   55.86967N   98.35633W
        08-Sep-1994     55.92333N    98.66634W   55.92883N   98.41517W
                        53.64500N   106.15800W   53.64333N  105.81067W
        11-Sep-1994     53.51900N   105.48233W   53.70433N  105.34650W
                        53.49117N   106.00517W   53.53767N  106.28000W
        13-Sep-1994     53.51733N   105.48183W   53.66017N  105.24450W
        14-Sep-1994     53.52167N   105.48050W   53.74967N  105.38450W
                        53.93367N   105.35000W   53.90200N  105.37634W
        15-Sep-1994     53.33067N   105.81433W   53.44700N  105.97350W
                        53.49133N   105.45050W   53.71200N  105.31883W
        16-Sep-1994     53.52000N   105.48067W   53.65750N  105.01950W
        17-Sep-1994     53.36100N   105.93784W   53.59817N  106.34866W
        18-Sep-1994     53.41450N   106.07133W   53.56283N  106.41734W
                        54.95267N   101.96133W   55.88883N   97.99500W
                        55.88883N    97.99500W   55.92300N   97.92367W
        19-Sep-1994     55.79833N    98.08283W   55.80353N   98.32050W
                        55.89717N    98.27634W   55.87133N   98.02666W

1996:   

        09-Jul-1996     53.68847N   105.48505W   53.77241N  105.10998W
                        53.78666N   104.81798W   53.75954N  105.10448W
                        53.42411N   105.93343W   53.62444N  106.19762W
        10-Jul-1996     53.68332N   105.48402W   53.94030N  105.21469W
        11-Jul-1996     53.96244N   104.92509W   53.83380N  105.21297W
        12-Jul-1996     53.68967N   105.48196W   53.83541N  105.29588W
        14-Jul-1996     53.68813N   105.47733W   53.77911N  105.26052W
                        53.78923N   105.28061W   53.84983N  105.32730W
        19-Jul-1996     53.45467N   105.96296W   53.54633N  106.19831W
        20-Jul-1996     53.93017N   105.14603W   53.99265N  105.14139W
                        53.89687N   105.28954W   53.85172N  105.36043W
                        53.85841N   105.40403W   53.77928N  105.37331W
                        53.64933N   105.16645W   53.76005N  104.90450W
        26-Jul-1996     53.58015N   106.29976W   53.54736N  106.18561W
        27-Jul-1996     53.91438N   104.97076W   53.89841N  104.92166W
        29-Jul-1996     53.52213N   105.48334W   53.62976N  105.22104W
                        53.78666N   104.82622W   53.72709N  104.98947W
                        53.48213N   105.91318W   53.65328N  106.13737W
        30-Jul-1996     53.46806N   106.13874W   53.56144N  106.39194W
                        54.95413N   101.96686W   54.87190N  101.89870W
                        55.87458N    98.37261W   55.88642N   98.19408W
        31-Jul-1996     55.80608N    98.11426W   55.78463N   98.33227W
                        55.87921N    98.62667W   55.87870N   98.26447W
                        55.77793N    98.41999W   55.80059N   98.19494W
        02-Aug-1996     55.79424N    97.88835W   55.80025N   98.15804W
                        55.90101N    98.30532W   55.88951N   98.23975W
        03-Aug-1996     55.87440N    98.24009W   55.79716N   98.45861W
        05-Aug-1996     55.79630N    97.87411W   55.89071N   98.19528W
                        55.99354N    98.50307W   55.94582N   98.59818W
                        55.91887N    98.63697W   55.85175N   98.41106W
        07-Aug-1996     55.79613N    97.87239W   55.81535N   98.11391W
                        55.82874N    98.32780W   55.85604N   98.20215W
        08-Aug-1996     55.87492N    98.37106W   55.92693N   98.20438W

7.1.2 Spatial Coverage Map

None.

7.1.3 Spatial Resolution

The spatial resolution of the original data used in the flux computations is a 
function of the aircraft speed (approximately 55 m/s), the digital recording 
rate (16 Hz in 1994, 32 Hz in 1996), and the anti-alias filtering applied to the 
data prior to recording (5.5 Hz).  This translates to a basic sampling 
resolution of approximately 12 m (1994) and 6 m (1996) for the Twin Otter. 

7.1.4 Projection

These data were collected at point locations.

7.1.5 Grid Description

None.

7.2 Temporal Characteristics

7.2.1 Temporal Coverage

Sounding data were collected from 25-May-1994 to 19-Sep-1994 and 09-Jul-1996 to 
08-Aug-1996.

7.2.2 Temporal Coverage Map

IFC-1:  25-May-1994 to 26-May-1994
        29-May-1994
        01-Jun-1994
        04-Jun-1994
        07-Jun-1994 to 11-Jun-1994
        13-Jun-1994

IFC-2:  20-Jul-1994 to 22-Jul-1994
        24-Jul-1994 to 29-Jul-1994
        01-Aug-1994 to 02-Aug-1994
        04-Aug-1994
        08-Aug-1994

IFC-3:  31-Aug-1994
        02-Sep-1994
        08-Sep-1994
        11-Sep-1994 to 19-Sep-1994

1996:   09-Jul-1996 to 12-Jul-1996
        14-Jul-1996
        19-Jul-1996 to 20-Jul-1996
        26-Jul-1996 to 27-Jul-1996
        29-Jul-1996 to 31-Jul-1996
        02-Aug-1996 to 03-Aug-1996
        05-Aug-1996
        07-Aug-1996 to 08-Aug-1996
       

7.2.3 Temporal Resolution

The aircraft data were recorded at a basic rate of 16 Hz in 1994 and 32 Hz in 
1996.  Flight durations were typically 3 to 3.5 hours.  On several occasions 
there were two flights per day. 

7.3 Data Characteristics

Data characteristics are defined in the companion data definition file 
(afm4toas.def).

7.4 Sample Data Record

Sample data format shown in the companion data definition file (afm4toas.def).

8. Data Organization

8.1 Data Granularity

All of the AFM-04 Twin Otter Aircraft Sounding Data are contained in one data 
set.

8.2 Data Format(s)

The data files contain numerical and character fields of varying length 
separated by commas.  The character fields are enclosed with single apostrophe 
marks.  There are no spaces between the fields. Sample data records are shown in 
the companion data definition file (afm4toas.def).

9. Data Manipulations

9.1 Formulae

See MacPherson (1990b).

9.1.1 Derivation Techniques and Algorithms

See MacPherson (1990b).

9.2 Data Processing Sequence

9.2.1 Processing Steps

1.  AFM-04 processed the data and sent them to BORIS.
2.  BORIS staff received the data, made necessary conversions to standard units, 
and loaded the data into the database.
3.  BORIS staff documented the data set and compiled basic statistics about the 
data.

See MacPherson (1988, 1990a, 1990b, 1996) and MacPherson and Bastian (1997) for 
more detailed information about the processing that AFM-04 did to the data 
before submitting them to BORIS.

9.2.2 Processing Changes

There are quite a number of selectable options in the playback program for the 
Twin Otter data.  These include the option to use the alternative (backup) wind 
computations if there should be a problem with the Litton 90/100 IRS. 

9.3 Calculations

9.3.1 Special Corrections/Adjustments

Calculation of wind components is described in MacPherson (1990b) and MacPherson 
and Morgan (1981).  The air velocity relative to the aircraft is measured by the 
true airspeed (TAS) and noseboom angles of attack and sideslip.  The TAS vector 
is then resolved into Earth axes (north, east, and vertical components).  From 
these are subtracted the aircraft inertial velocity components measured by a 
Litton 90/100 IRS, to get the three components of the wind velocity in Earth-
fixed axes. 

An alternative, or backup, wind system is employed on the Twin Otter in case the 
Litton 90 is unserviceable (rare).  For this system, known as the NAE/DOP winds, 
the aircraft inertial velocity relative to the Earth is measured in aircraft 
axes by a system incorporating complementary filtering in real time on the 
aircraft microprocessor.  A system of accelerometers and rate gyros provides the 
high-frequency components to this filter; the Decca 3-Axis Doppler radar 
provides the low-frequency components.  The resulting calculated velocity 
components in A/C axes are subtracted from the TAS components to get the three 
components of wind in A/C axes.  These are then resolved into Earth axes using 
the pitch, roll, attitude, and heading. 

9.3.2 Calculated Variables

None given.

9.4 Graphs and Plots

None.

10. Errors

10.1 Sources of Error

Errors can result from a number of different sources.  The flux measurements are 
subject to possible errors relating to the measurements from the IRS.

A problem was detected with the ESRI CO2 analyzer.  Possible reasons for this 
problem are listed in MacPherson (1996).  As a result of this problem with the 
ESRI, data from the LI-COR were reported for the CO2 and H2O fluxes.

10.2 Quality Assessment

10.2.1 Data Validation by Source

Great care has been taken in the collection and analysis of the Twin Otter data.  
The wind measuring system is continually monitored for accuracy using techniques 
such as wind boxes, control input cases, and intercomparisons with other 
aircraft (Dobosy et al., 1997).  Cospectral plots have been used to check the 
flux contributions at all wavelengths to ensure that they were not contaminated 
by inadequate compensation for aircraft motion. 

Aircraft data were compared at various BOREAS workshops.  This led to the 
decision to include all three sets of fluxes (i.e., from raw, detrended, and 
high-pass filtered time histories) in the database. 

10.2.2 Confidence Level/Accuracy Judgment

See Section 10.2.1.

10.2.3 Measurement Error for Parameters

Not available at this revision.

10.2.4 Additional Quality Assessments

See Dobosy et al. (1997).

10.2.5 Data Verification by Data Center

Data were examined for general consistency and clarity.

11. Notes

11.1 Limitations of the Data

None given.

11.2 Known Problems with the Data

None given.

11.3 Usage Guidance

None.

11.4 Other Relevant Information

None.

12. Application of the Data Set

These data can be used to obtain study area and regional scale estimates of the 
various fluxes.

13. Future Modifications and Plans

None given.

14. Software

14.1 Software Description

None given.

14.2 Software Access

None given.

15.   Data Access

15.1  Contact for Data Center/Data Access Information

These BOREAS data are available from the Earth Observing System Data and 
Information System (EOS-DIS) Oak Ridge National Laboratory (ORNL) Distributed 
Active Archive Center (DAAC). The BOREAS contact at ORNL is:

ORNL DAAC User Services
Oak Ridge National Laboratory
(865) 241-3952
ornldaac@ornl.gov
ornl@eos.nasa.gov

15.2  Procedures for Obtaining Data

BOREAS data may be obtained through the ORNL DAAC World Wide Web site at 
http://www-eosdis.ornl.gov/ or users may place requests for data by 
telephone, electronic mail, or fax.

15.3  Output Products and Availability

Requested data can be provided electronically on the ORNL DAAC's anonymous FTP 
site or on various media including, CD-ROMs, 8-MM tapes, or diskettes.

The complete set of BOREAS data CD-ROMs, entitled "Collected Data of the Boreal 
Ecosystem-Atmosphere Study", edited by Newcomer, J., et al., NASA, 1999, are 
also available.

16. Output Products and Availability

16.1 Tape Products

Not applicable.

16.2 Film Products

Not applicable.

16.3 Other Products

These data are available on the BOREAS CD-ROM series.

17. References

17.1 Platform/Sensor/Instrument/Data Processing Documentation

The Twin Otter Atmospheric Research Aircraft and its instrumentation have been 
described in the following reports available from the NRC:

MacPherson, J.I. 1988. NAE Twin Otter Operations in FIFE. National Research 
Council Canada Report LTR-FR-104. 

MacPherson, J.I. 1989. NAE Twin Otter Operations in the 1988 Eulerian Model 
Evaluation Field Study. National Research Council Canada Report LTR-FR-107. 

MacPherson, J.I. 1990a. NAE Twin Otter Operations in FIFE 1989. National 
Research Council Report LTR-FR-113. 

MacPherson, J.I. 1990b. Wind and Flux Calculations on the NAE Twin Otter. NAE 
Laboratory Technical Report LTR-FR-109. National Research Council. January 1990. 

MacPherson, J.I. 1992. NRC Twin Otter Operations in the 1991 California Ozone 
Deposition Experiment.  National Research Council of Canada Report LTR-FR-118. 
May 1992.

MacPherson, J.I. 1996. NRC Twin Otter Operations in BOREAS 1994. Laboratory 
Technical Report LTR-FR-129. National Research Council Canada. April 1996.

MacPherson, J.I. and M. Bastian. 1997. NRC Twin Otter Operations in BOREAS 1996. 
Laboratory Technical Report LTR-FR-134.  National Research Council of Canada. 
November 1997.

MacPherson, J.I. and J.M. Morgan. 1981. The N.A.E. Twin Otter Atmospheric 
Research Aircraft. National Research Council Report LTR-FR-80. 

MacPherson, J.I. and S.W. Baillie. 1986. The N.A.E. Atmospheric Research 
Aircraft. National Research Council Report, NAE Misc 62.
MacPherson, J.I., R.J. Grossman, and R.D. Kelly. 1992. Intercomparison Results 
for FIFE Flux Aircraft. Journal of Geophysical Research 97(D17):18,499-18,514.

17.2 Journal Articles and Study Reports

Barr, A.G., A.K. Betts, R.L. Desjardins, and J.I. MacPherson. 1997. Comparison 
of regional surface fluxes from boundary-layer budgets and aircraft measurements 
above boreal forest. Journal of Geophysical Research 102(D24): 29,213-29,218.
 
Desjardins, R.L., J.I. MacPherson, L. Mahrt, P. Schuepp, E. Pattey, H. Neumann, 
D. Baldocchi, S. Wofsy, D. Fitzjarrald, H. McCaughey, and D.W. Joiner. 1997. 
Scaling up flux measurements for the boreal forest using aircraft-tower 
combinations. Journal of Geophysical Research 102(D24): 29,125-29,133.

Dobosy, R.J., T.L. Crawford, J.I. MacPherson, R.L. Desjardins, R.D. Kelly, S.P. 
Oncley, and D.H. Lenschow. 1997. Intercomparison among four flux aircraft at 
BOREAS in 1994.  Journal of Geophysical Research 102(D24):29,101-29,111.

MacPherson, J.I. and A.K. Betts. 1997. Aircraft encounters with strong coherent 
vortices over the boreal forest. Journal of Geophysical Research 102(D24): 
29,231-29,234.

MacPherson, J.I. and R.L. Desjardins. 1991. Airborne Tests of Flux Measurement 
by the Relaxed Eddy Accumulation Technique. Proceedings of the Seventh Symposium 
on Meteorological Observations and Instrumentation.  American Meteorological 
Society. New Orleans. January, 1991.

Ogunjemiyo, S., P.H. Schuepp, J.I. MacPherson, and R.L. Desjardins. 1997. 
Analysis of flux maps versus surface characteristics from Twin Otter grid 
flights in BOREAS 1994.  Journal of Geophysical Research 102(D24): 29,135-
29,145.

Sellers, P. and F. Hall. 1994. Boreal Ecosystem-Atmosphere Study: Experiment 
Plan. Version 1994-3.0, NASA BOREAS Report (EXPLAN 94). 

Sellers, P. and F. Hall. 1996. Boreal Ecosystem-Atmosphere Study: Experiment 
Plan. Version 1996-2.0, NASA BOREAS Report (EXPLAN 96). 

Sellers, P., F. Hall, and K.F. Huemmrich. 1996. Boreal Ecosystem-Atmosphere 
Study: 1994 Operations. NASA BOREAS Report (OPS DOC 94). 

Sellers, P., F. Hall, and K.F. Huemmrich. 1997. Boreal Ecosystem-Atmosphere 
Study: 1996 Operations. NASA BOREAS Report (OPS DOC 96). 

Sellers, P., F. Hall, H. Margolis, B. Kelly, D. Baldocchi, G. den Hartog, J. 
Cihlar, M.G. Ryan, B. Goodison, P. Crill, K.J. Ranson, D. Lettenmaier, and D.E. 
Wickland. 1995. The boreal ecosystem-atmosphere study (BOREAS): an overview and 
early results from the 1994 field year. Bulletin of the American Meteorological 
Society. 76(9):1549-1577. 

Sellers, P.J., F.G. Hall, R.D. Kelly, A. Black, D. Baldocchi, J. Berry, M. Ryan, 
K.J. Ranson, P.M. Crill, D.P. Lettenmaier, H. Margolis, J. Cihlar, J.
Newcomer, D. Fitzjarrald, P.G. Jarvis, S.T. Gower, D. Halliwell, D. Williams, B. 
Goodison, D.E. Wickland, and F.E. Guertin. 1997. BOREAS in 1997:
Experiment Overview, Scientific Results and Future Directions. Journal of 
Geophysical Research 102(D24): 28,731-28,770.

17.3 Archive/DBMS Usage Documentation

None.

18. Glossary of Terms

None.

19. List of Acronyms

    AFM     - Airborne Fluxes and Meteorology
    AGL     - Above Ground Level
    ASCII   - American Standard Code for Information Interchange
    BOREAS  - BOReal Ecosystem-Atmosphere Study
    BORIS   - BOREAS Information System
    CD-ROM  - Compact Disk-Read-Only Memory
    DAAC    - Distributed Active Archive Center
    DAT     - Digital Archive Tape
    EOS     - Earth Observing System
    EOSDIS  - EOS Data and Information System
    FIFE    - First ISLSCP Field Experiment
    FIS     - FIFE Information System
    GMT     - Greenwich Mean Time
    GPS     - Global Positioning System
    GSFC    - Goddard Space Flight Center
    HP      - high pass
    HTML    - HyperText Markup Language
    IAR     - Institute for Aerospace Research  
    IFC     - Intensive Field Campaign
    INS     - Inertial Navigation System
    IRS     - Inertial Reference System
    ISLSCP  - International Satellite Land Surface Climatology Project
    MSL     - Mean Sea Level
    NAD83   - North American Datum of 1983
    NAE     - National Aeronautical Establishment
    NASA    - National Aeronautics and Space Administration
    NCAR    - National Center for Atmospheric Research
    NRC     - National Research Council, Canada    
    NSA     - Northern Study Area
    ORNL    - Oak Ridge National Laboratory
    PANP    - Prince Albert National Park
    RMS     - Root Mean Square
    SSA     - Southern Study Area
    TAS     - True Air Speed
    URL     - Uniform Resource Locator

20. Document Information

20.1 Document Revision Date

Written: 01-Jan-1993
Revision Date: 10-Aug-1999

20.2 Document Review Date(s)

     BORIS Review: 06-Aug-1999    
     Science Review:
 
20.3 Document ID

20.4 Citation

These data were measured by the Twin Otter Atmospheric Research Aircraft 
operated by the National Research Council of Canada.  J.I. MacPherson of NRC was 
the Principal Investigator responsible for the operation of the aircraft in 
BOREAS and the processing of the data. Other scientists on the Twin Otter 
project team were Ray Desjardins of Agriculture Canada and Peter Schuepp of 
McGill University. Funding for the Twin Otter participation in BOREAS was 
provided by Agriculture Canada, NSERC and the National Research Council of 
Canada. 

20.5 Document Curator

20.6 Document URL

KEYWORDS
---------
CARBON DIOXIDE CONCENTRATION
OZONE CONCENTRATION
TEMPERATURE
BOUNDARY LAYER
AFM04_Soundings.doc
08/21/99