Transcript Slide 1
Courtesy: Zach Allen A NEW HAMPSHIRE GROUND-LEVEL OZONE POLLUTION FORECASTING TOOL USING METEOROLOGICAL CRITERIA 2008 November 5 Northeast Regional Operational Workshop Presenter: Laura Landry, Plymouth State University Introduction New Hampshire Department of Environmental Services (NHDES) has forecasted ozone pollution for over 15 years Ozone exposure causes a wide range of respiratory problems (AIRNow 2008) Primarily concerned with Environmental Protection Agency’s (EPA) National Ambient Air Quality Standard (NAAQS) for ozone Based on daily maximum 8-hour average ozone concentration Introduction Since March 2008, a new NAAQS for ozone has been implemented, lowered from 84ppb to 75ppb Previously used forecasting methods have become less accurate Motivation: To develop a new forecasting guide for predicting the new standard of 75ppb Results will help answer questions of: How much variation in meteorological criteria will there be between air monitoring sites? How will criteria compare when using two different time periods of data? Introduction Meteorological conditions behind ozone development Sunny skies High surface temperatures Calm to light winds Transport of pollution New Hampshire lies downwind of major pollution sources Methodology Selection of air quality monitoring sites Sites 1. were selected base on: Locations where most exceedance days occur More problematic to forecast Larger sample size on which to base the analysis 2. Locations not adjacent to each other Methodology New Hampshire Southern sites report most of exceedance days Site elevations range from 0 to 150m Miller State Park is an exception at about 700m Methodology Previous research conducted by Jeffs (2007), a Master’s thesis at Plymouth State University Created an ozone forecasting guide for 65ppb Utilized a dataset from 2002-2005 This study followed similar methodology EPA suggests an air quality climatology as about 4 years (EPA 1999) Used two datasets of June-August 2004-2007 2002-2007 Methodology Ozone data Daily maximum 8-hour average ozone concentration Source: NHDES Meteorological data Surface observations from KCON, KEEN, KASH, KPSM, and Miller State Park Source: National Weather Service, Plymouth State University, NHDES Radiosonde Source: data from KGYX Plymouth State University Methodology Analysis was done using the Criteria Method EPA-recommended method for creating air quality forecast guides (EPA 1999) Subjective analysis that focuses on exceedance days Determines threshold values Methodology Nashua 850hPa Temperature at 12 UTC 110 100 8-hour ozone concentration (ppb) 90 80 70 60 50 40 30 20 10 0 0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 850hPa temperature (°C) 16.0 18.0 20.0 22.0 24.0 Methodology Meteorological parameters: Daily maximum surface temperature 850hPa temperature (12 UTC) Surface wind speed and direction (12 & 18 UTC) Cloud cover (12 & 18 UTC) Times were chosen based on: 12 UTC: morning conditions prior to a potential high ozone event 18 UTC: afternoon conditions when ozone typically reaches its daily maximum value RESULTS Results Comparing criteria of air monitoring site to site… Daily observations Maximum 12 surface temperature: ≥ 83˚F UTC observations 850hPa temperature: ≥ 12˚C Surface wind speed: ≤ 5 knots Surface wind direction: Southwesterly to southerly Cloud cover: ≤ FEW Results Comparing criteria of air monitoring site to site… 18 UTC observations Surface wind speed: ≤10 knots Surface wind direction: Westerly to southwesterly Cloud cover: ≤ SCT Results from Miller State Park varied most from all other sites Site to Site Comparison Miller State Park Nashua 2004-2007 2004-2007 Variable Threshold N Range Variable Threshold N Range Max Surface Temperature ≥ 80°F 14 73-96°F Max Surface Temperature ≥ 86 °F 17 77-95°F 12 UTC OBSERVATIONS 12 UTC OBSERVATIONS 850hPa Temperature ≥ 11.4°C 18 9.4-19.6°C 850hPa Temperature ≥ 12 °C 17 9.419.8°C Wind Speed ≤ 14 kts 13 3-14 kts Wind Speed ≤ 5 kts 15 0-6 kts Wind Direction 200-260° 15 87-295° Wind Direction 180-290° 3 180-290° Cloud Cover - - - Cloud Cover ≤ SCT 14 CLRBKN 18 UTC OBSERVATIONS 18 UTC OBSERVATIONS Wind Speed ≤ 14 kts 13 5-19 kts Wind Speed ≤ 10 kts 16 1-10 kts Wind Direction 200-250° 14 117-287° Wind Direction 200-300° 13 110-300° Cloud Cover - - - Cloud Cover ≤ SCT 15 CLRBKN Results Comparing criteria among different time periods of data among the same air monitoring site… Dataset Comparison Portsmouth 2002-2007 2004-2007 Variable Threshold N Range Variable Threshold N Range Max Surface Temperature ≥ 82°F 19 81-97°F Max Surface Temperature ≥ 82°F 10 81-95°F 12 UTC OBSERVATIONS 12 UTC OBSERVATIONS 850hPa Temperature ≥ 12.4°C 19 12.420.8°C 850hPa Temperature ≥ 12.4°C 10 12.419.8°C Wind Speed ≤ 7 kts 19 1-8 kts Wind Speed ≤ 5 kts 10 1-8 kts Wind Direction 190-290° 16 150-290° Wind Direction 190-270° 8 150-270° Cloud Cover ≤ SCT 17 CLR-BKN Cloud Cover ≤ FEW 10 CLRBKN 18 UTC OBSERVATIONS 18 UTC OBSERVATIONS Wind Speed ≤ 10 kts 19 3-10 kts Wind Speed ≤ 8 kts 10 3-9 kts Wind Direction 180-240° 17 120-260° Wind Direction 180-260° 9 120-260° Cloud Cover ≤ BKN 17 CLR-OVC Cloud Cover ≤ SCT 10 FEWOVC Summary This study developed an ozone forecasting guide for the NHDES The criteria method from the EPA Subjectively analyzed meteorological threshold values Threshold values indicate a high probability of an exceedance day Conclusions Air monitoring site to site comparison: Similar threshold values among sites Miller State Park appeared to be an outlier Could be due to high elevation Transport may be more of an issue Dataset to dataset comparison: No significant variation in threshold values In this study, the length of the dataset did not have a large effect on results Questions? References: AIRNow, accessed 2008: Ozone and Your Health. [http://www.airnow.gov/index.cfm?action= static.ozone2] EPA, 1999: Guideline for Developing an Ozone Forecasting Program. EPA: Office of Air Quality Planning and Standards. Jeffs, Kim, 2007: Development of Meteorological Criteria for Forecasting Air Quality in New Hampshire. Plymouth State University: Master of Science Thesis Project.