TECHNICAL MEMORANDUM REVIEW PROCESS FOR 2016, 2017, 2018 FIRST QUARTER, AND 2018 SECOND QUARTER METEOROLOGICAL AND AIR QUALITY DATASETS PREPARED FOR: Imperial Irrigation District PREPARED BY: Formation Environmental DATE: August 15, 2018 1 INTRODUCTION AND BACKGROUND Hourly meteorological and air quality data are collected by six permanent stations located around the Salton Sea at Bombay Beach, Naval Test Base, Salton City, Salton Sea Park, Sonny Bono, and Torrez Martinez. Maintenance and operation of these stations is currently conducted by Air Sciences Inc. (Air Sciences). After data collection, Air Sciences also completes a quality assurance and quality control (QAQC) review and conducts data validation. To assure high-quality work products, Formation Environmental (Formation) completes an additional review of the data prior to its release to the public. This memorandum describes: Formation’s supplementary data review process; comments and questions prepared by Formation on the 2016, 2017, 2018 first quarter, and 2018 second quarter datasets; and responses to comments on the aforementioned datsets provided by Air Sciences. 2 DATA REVIEW PROCESS The following section describes the primary and supplementary meteorological and air quality data review processes. 2.1 PRIMARY DATA REVIEW PROCESS Air Sciences’ data review and validation processes are described in the technical memorandum, Salton Sea – Ambient Air Quality Monitoring Network 2016-2017 Data Review, dated August 15, 2018. This document is provided as Attachment 1. Hereafter, it is referred to as the SSAQMN Tech Memo. 2.2 SUPPLEMENTARY DATA REVIEW PROCESS Prior to public release of the meteorological and air quality datasets, Formation conducts an internal supplementary review process, which consists of two phases: • Screening of data relative to a series of criteria developed in consultation with the SSAQMN Tech Memo 1 REVIEW PROCESS FOR 2016, 2017, 2018 FIRST QUARTER, AND 2018 SECOND QUARTER METEOROLOGICAL AND AIR QUALITY DATASETS • Development and review of data through diagnostic plots The data screening process and the development of the diagnostic plots were completed in R: A Language and Environment for Statistical Computing (hereafter referred to as R). The two phases of the supplementary review process are discussed in the following subsections. 2.2.1 DATA SCREENING PROCESS Each of the meteorological and air quality datasets are independently screened after the initial development and data QAQC process. The following table summarizes the supplementary data screens on a parameter basis. Values meeting the criteria specified below are flagged for further review. TABLE 1. SSAQMN SUPPLEMENTARY DATA REVIEW Parameter Independent Data Screens Barometric Pressure - Values less than 0.9 atm - Values greater than 1.1 atm PM Concentrations - Values (PMC, PM2.5, PM10 local, and PM10 STP) less than -15 ug/cubic meter - Values for which the sum of PM2.5 and PM10 is not equal to PMC (within + 0.1 ug/cubic meter) Precipitation - Values less than 0 mm - Values greater than 10 mm Relative Humidity - Values less than 0% - Values greater than 100% Temperature - Values screened against monthly minimum temperatures - Values screened against monthly maximum temperatures Wind Direction - Values less than 0 degrees - Values greater than 360 degrees - Values that are constant for 4 or more hours Wind Direction Standard Deviation - Values less than 0 degrees - Values greater than 100 degrees Wind Gust (maximum measured at - Values less than 0 m/s 10 m) - Values greater than 20 m/s - Values that are constant for 4 or more consecutive hours Wind Speed (horizontal) - Values less than 0 m/s - Values greater than 20 m/s - Values that are constant for 4 or more consecutive hours Secondarily, the following situations are identified: • Days for which the maximum temperature occurs prior to 9 a.m. • Times for which the temperature measured at 10 m minus the temperature measured at 2 m are positive during the day (indicating that the 10 m temperature exceeds the surface [2 m] temperature) or negative at night (indicating that the surface [2 m] temperature exceeds the 10 m temperature) 2 REVIEW PROCESS FOR 2016, 2017, 2018 FIRST QUARTER, AND 2018 SECOND QUARTER METEOROLOGICAL AND AIR QUALITY DATASETS • Days for which the maximum solar radiation does not occur mid-day (from 11 a.m. to 2 p.m.) • Times when the PM10 concentrations are less than the PM2.5 concentrations These situations may occur due to meteorological conditions and are of lesser importance than the screening criteria outlined in Table 1. Unless other considerations indicate the need for further review, these situations are documented but not flagged for further review. An additional data screen determines whether the Row Has Invalid field is properly completed. The Invalid Reasons field is also reviewed to confirm that the comments apply only to fields provided in the datasets. 2.2.2 REVIEW OF DIAGNOSTIC PLOTS For the second phase of the supplementary review process, the following diagnostic plots are developed and reviewed: • Time series plots by parameter for all stations • Time series plots by parameter for each individual station Additionally, wind roses are created from the 10 m wind speed data. Concurrent review of the by-parameter time series plots for all stations and by individual station allows for inconsistencies between stations and potential issues at individual stations to be readily identified. Wind roses are reviewed for consistency with known prevailing wind speed and directionality patterns at each station. 3 SUMMARY OF COMMENTS AND RESPONSES The following subsections provide a listing of the raw comments and questions provided to Air Sciences by Formation on each of the three datasets: 2016 and 2017 all quarters, 2018 first quarter, and 2018 second quarter. 3.1 2016 AND 2017 DATASETS The following comments and questions were prepared by Formation on the 2016 and 2017 datasets. Responses provided by Air Sciences follow each comment. 1. There are relative humidity measurements at 2m during 2016 Q1 and Q3 at Bombay Beach, 2016 Q1 and Q2 at Salton Sea Park, and 2016 Q1, Q2, and Q3 at Torres Martinez which are greater than 100%. According to the QAPP, "the humidity range of the humidity sensor is from 0-100 percent with an accuracy of ±0.8 percent when the temperature is at 23°C." Please clarify why these measurements are included in the final dataset. 3 REVIEW PROCESS FOR 2016, 2017, 2018 FIRST QUARTER, AND 2018 SECOND QUARTER METEOROLOGICAL AND AIR QUALITY DATASETS Response: “The stated accuracy for the RH probe is correct. However, the instruments do drift as they age (up to 1% per year). In addition, the EPA audit tolerance is 8%, so a drift below that will not be flagged for recalibration. The current logger program forces the maximum to 100% so this won't come up again, but the decision was made to leave values >100% for older data based on the above.” 2. There are ambient relative humidity measurements during 2016 Q3 at Naval Test Base which are below 0%. Please clarify why these measurements are included in the final dataset. Response: “From our review it appears this only affects the RH sensor on the TEOM, not the 2m Temp/RH probe. Since the TEOM RH is not reported with the ‘public’ TEOM dataset, this was not prioritized for review/flagging of older data.” 3. The sonic 2D vector average wind direction measurements during 2016 Q1 at Sonny Bono do not span full range of 0-360 degrees. Wind direction measurements from other time frames at this station show wind directions from the full range. Please review and clarify. Response: “You are correct and this should have been invalidated. We had a miscommunication with invalidating sonic data at SB. This has been corrected.” 4. Similarly, the wind direction measurements at 10m during 2016 Q1 at Sonny Bono do not span full range of 0-360 degrees. Please review and clarify. Additionally, please comment on the gap in collection (i.e. 2016 Q2 and 2016 Q3 data is missing). Response: “From Tim: Given the full sonic invalidation at SB for this time period, and given no other information available to us to invalidate the WD_10m (vane) data – we opted to keep the SB data for the first part of 2016. There isn’t a full compass span for WD_10m for those limited ~45 days, but we have nothing as a basis to flunk the data…the CARB audit on 2/24/2016 included WD and indicated passing for all WD checks so we assumed that the 1/1 to 2/24 was good. Wind direction failed the close-out audit at SB on 10/3/2016 and so we had to invalidate back to the last ‘known good’ point, which was the CARB audit on 2/24.” 5. When comparing the wind speed measurements at 1m and 2m, it seems that some instruments have a different lower cutoff value to reflect calm or still conditions. Is this correct? Response: “Yes, the minimum threshold was set inconsistently in the Ecotech system. We did not attempt to standardize the minimums for older data, but the current logger program is consistent for 10m WS at all sites.” 6. The PM2.5 filter load during 2017 Q3 at Torres Martinez appears anomalous (i.e. inconsistent with other data). Please review and clarify. Response: “Yes, this should have been flagged and is now fixed.” 4 REVIEW PROCESS FOR 2016, 2017, 2018 FIRST QUARTER, AND 2018 SECOND QUARTER METEOROLOGICAL AND AIR QUALITY DATASETS 7. The PM2.5 mass accumulations are negative during 2017 Q3 at Salton City and 2017 Q1, Q2 and Q3 at Salton Sea Park. Please review and clarify. Response: “This correlates with brief (1-hour) periods where the TEOM calculates a negative concentration due to an instability in the instrument. We don't think it is an issue in regards to the concentration data being invalid (other than the brief period of extreme negative conc.), but we are getting clarification from Thermo on why this happens and if it's a problem.