Utah Atmospheric Trace Gas & Air Quality (UATAQ) Laboratory
Teledyne T200 Chemiluminescence Nitrogen Oxides Analyzer
Courtesy of Dr. John Lin, University of Utah - Department of Atmospheric Sciences (John.Lin@utah.edu)
Prepared by Haley Humble, December 13th, 2024 (Haley.Humble@utah.edu)
 
Period of Interest: 2024-07-01 to 2024-08-31
Region of Interest: Salt Lake Valley, Utah
 
Site Configuration (including coordinates and elevation): 
https://github.com/uataq/data-pipeline/blob/main/config/site_config.csv

CALIBRATION METHOD:
During the campaign, the T200 calibration was done every 1-2 weeks during down times. Calibration standards were diluted using the Teledyne 751H Zero Air System and Dilution Calibrator T700u, using zero air, and an EPA Protocol Gas mixture with certified concentrations. A two-point calibration at 0 and 300 ppb were performed per the Teledyne T200 Manual instructions. These calibration were used to correct and identify shifts in the baseline. All maintenance done by the UATAQ Lab are maintained and stored in a GitHub repository since 2021 (see links below).
 
DATA ORGANIZATION:
REMOVED DATA:
Excluded 12 hours before and after calibrations and calibration checks. The only other data removed was due to power outages > 2 hours. The warmup period of 1 hour was removed.

Dates removed due to Calibrations or Calibration Checks:
 6/13/24 18:55 
 7/10/24 19:30	 
 7/19/24 10:00	 
 7/24/24 10:00	 
 7/31/24 16:45	
 8/08/24 17:30	      
 8/13/24 18:00	
 8/19/24 17:15
 8/29/24 14:15	 

CALIBRATION CORRECTION: 
Divided the calibration time periods into distinct segments and applied the following steps to each segment. The calibration checks were removed, but not segmented into new sections. Only segmented when zero and span values were reset. 

LOWEST 1% CALCULATION: 
Computed the mean of the lowest 1% of non-missing values for no2_ppb and no_ppb.

ABSOLUTE VALUES APPLIED: 
Added the absolute values of the lowest 1% correction to 'NO2_ppb' and 'NO_ppb' for the corresponding segment(s). The
corrected sum of NO2_corrected and NO_corrected values was then added together to determine the 'NOx_corrected'.This method was justified since the T200 does the same thing to measure NOx (NO + NO2 = NOx).

USOS ICARTT FILE: NO_NO2_NOX_UOU_20240701_R0.ict
PI_CONTACT_INFO: 135 S 1460 E Rm 819, Salt Lake City, UT 84112; John.Lin@utah.edu         
PLATFORM: On top of the William Browning building      
LOCATION: Lat 40.763, Lon -111.848, Elevation 1,430 m, Inlet Height 31.5 m                                                   
ASSOCIATED_DATA: see README_USOS_T200_UOU.txt                                                                                
INSTRUMENT_INFO: Teledyne Model T200 Nitrogen Oxides Analyzer                                 
DATA_INFO: Units are ppb                                                                                                    
UNCERTAINTY:T200 manual; Lower Detection Limit: < 0.4 ppb, Precision: 0.5% of reading above 50 ppb                          
ULOD_FLAG: -7777                                                                                                           
ULOD_VALUE: N/A                                                                                                            
LLOD_FLAG: -8888                                                                                                           
LLOD_VALUE: N/"                                                                                                           
DM_CONTACT_INFO: Haley Humble,University of Utah, Haley.Humble@utah.edu                                                     
PROJECT_INFO: https://csl.noaa.gov/groups/csl7/measurements/2024usos/                                                       
STIPULATIONS_ON_USE: N/A                                                                                                   
OTHER_COMMENTS: Futher information about the UATAQ Sites: https://github.com/uataq/data-pipeline/blob/main/config/site_config.csv

ICARTT FILE VARIABLES:
Time_UTC, 2024-07-01 00-00-00_seconds_since_midnight_UTC       
no_ppb,ppb, NO concentration prior to correction
no2_ppb,ppb, NO2 concentration prior to correction
nox_ppb,ppb, NOX concentration prior to correction
no_corrected,ppb, NO concentration corrected
no2_corrected,ppb, NO2 concentration corrected
nox_corrected,ppb, NOX concentration corrected