Bisley Ozone 4-2008 to 4- 2012 Additional QA

Data File Identifier: 
Bisley Ozone 4-2008 to 4- 2012 Additional QA
Quality Control Level: 
Additional Quality Control-Values corrected for calibration/other
Number of header rows in file(s): 

The Luquillo Critical Zone Observatory has a series of sites collecting information about the landscape and climate of the Luquillo Mountains in Puerto Rico. The Bisley Lower Tower (pictured in Figure 5), which is a 25 m high walk-up tower in the Bisley watershed, is one of the eight stations monitoring weather and rainfall. Bisley is at tree canopy level and at an elevation of 352 m above sea level. It is precisely located at Bisley Lower Tower 18° 18' 51.8616" N, 65° 44' 41.676" W in a Tabanuco forest. Bisley Lower Tower includes many instruments for measuring climate conditions. The ozone instrument is a 2B technologies Model 202 Ozone Monitor (see Figure 4) and has collected ozone level information every fifteen minutes since April 24, 2008.
The data from the 2B technologies Model 202 Ozone Monitor covered a period from April 24, 2008 at 6:00 pm to April 24, 2012 at 8:30 am. The data includes the average, maximum, minimum and standard deviation of ozone in parts per billion (ppb) for each 15 minute time interval. The data set also recorded the temperature in degrees Celsius for each time interval. At certain points, the ozone instrument stopped working for anywhere between a couple hours to a couple months, so the data has some holes. Data from 2011 is completely missing due to equipment failure. Since, however, the data encompasses almost three years, it will be suitable to analyze for this study.
In cleaning up the field data, rows (i.e. 15 minute intervals) were deleted where the machine was clearly not working properly. These instances included when the value for any measurement of ozone was blank, written words or letters, negative numbers, or a meaningless value such as “-6999” or “-999” that the instrument produced to indicate failure. Additionally, unusually low points less than 10 ppb that did not vary with temperature were eliminated. Most of these points were from 2010 when the sensitivity of the instrument to low levels of ozone was questionable. The machine stopped working at various points for a few minutes (maybe related to maintenance) to over a year in 2011. The data set includes at least 500 hours for each month of the year. While some of the 15 minute maximums and minimums above 10 ppb from 2010 were outside the range of the other years, the daily means and medians were similar to other years. There was no systematic pattern in the highs and lows, so 2010 values were ultimately left in. Furthermore, removing these values does not change the results.
For most of the data analysis, the average ozone value in parts per billion (ppb) for each 15-minute interval was used. While the range of values from the largest maximum and lowest minimum for the entire data set is large, the average values for each 15 minute intervals only range from 10 ppb to 148.2 ppb. The average for the overall data set is 24.16 ppb, as seen in Table 1, which is well below the US 8-hour standard of 75 ppb. Only 438 specific 15-minute intervals out of 57,917 reach above the standard of 75 ppb, and only on 6 days does it reach an 8-hour average above the limit.

From Date: 
Thu, 04/24/2008 - Tue, 04/24/2012
Research Location: 
Core Area(s) and/or Keywords: 

Bisley, ozone, temperature, relative humidity, precipitation, solar radiation, wind, volatile organic compounds, nitrogen oxides, sunlight, pollution

Date and time
Record ID
Average O3
O3 Maximum
O3 Minimum
Average temperature
Stat Fan
Stat 2B
Stat Zero
Publish to National CZO: