A NEW HAMPSHIRE GROUND-LEVEL OZONE

POLLUTION FORECASTING TOOL USING

METEOROLOGICAL CRITERIANortheast Regional Operational WorkshopPresenter: Laura Landry, Plymouth State University

2008 November 5

Courtesy: Zach Allen

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 were selected base on:

1. Locations where most exceedance days occurMore problematic to forecastLarger sample size on which to base

the analysis

2. Locations not adjacent to each other

Methodology

Southern sites report most of exceedance days

Site elevations range from 0 to 150m Miller State Park is an

exception at about 700m

New Hampshire

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 data from KGYX

Source: 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

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 surface temperature: ≥ 83˚F 12 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 knotsSurface wind direction: Westerly to

southwesterlyCloud cover: ≤ SCT

Results from Miller State Park varied most from all other sites

Site to Site Comparison

2004-2007Variable Thresho

ldN Range

Max Surface Temperature ≥ 80°F 14 73-96°F

12 UTC OBSERVATIONS

850hPa Temperature ≥ 11.4°C 18 9.4-19.6°C

Wind Speed ≤ 14 kts 13 3-14 kts

Wind Direction

200-260° 15 87-295°

Cloud Cover - - -

18 UTC OBSERVATIONS

Wind Speed ≤ 14 kts 13 5-19 kts

Wind Direction

200-250° 14 117-287°

Cloud Cover - - -

Miller State Park Nashua

2004-2007Variable Thresh

oldN Range

Max Surface Temperature ≥ 86 °F 17 77-95°F

12 UTC OBSERVATIONS

850hPa Temperature ≥ 12 °C 17

9.4-19.8°C

Wind Speed ≤ 5 kts 15 0-6 kts

Wind Direction

180-290° 3 180-290°

Cloud Cover ≤ SCT 14CLR-BKN

18 UTC OBSERVATIONS

Wind Speed ≤ 10 kts 16 1-10 kts

Wind Direction

200-300° 13 110-300°

Cloud Cover ≤ SCT 15CLR-BKN

Results

Comparing criteria among different time periods of data among the same air monitoring site…

Dataset Comparison

2002-2007 2004-2007Variable Thresho

ldN Range Variable Thresh

oldN 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

12.4-20.8°C

850hPa Temperature ≥ 12.4°C 10

12.4-19.8°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

Direction190-270° 8 150-270°

Cloud Cover ≤ SCT 17 CLR-BKN Cloud Cover ≤ FEW 10CLR-BKN

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

Direction180-260° 9 120-260°

Cloud Cover ≤ BKN 17 CLR-OVC Cloud Cover ≤ SCT 10FEW-OVC

Portsmouth

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.