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New Hampshire Monitoring Values and Trajectories October 27, 2011

 

New Hampshire’s 8-Hour Ozone Monitoring Values and 

Airmass Trajectories 

Updated New Hampshire ozone data and design values for the period of 2009 through 2011 are detailed 

in the table below. All 8-hour ozone design values in New Hampshire continue to measure well below 

the ozone National Ambient Air Quality Standard (NAAQS) of 75 parts per billion (ppb). 

2009 – 2011 8-Hour Ozone Design Values by Monitor, parts-per-billion (ppb) 

Location Monitor 

ID 

2009-11 

Design Value 

2009 

4th Max 

2010 

4th Max 

2011 

4th Max 

 Camp Dodge 330074002 59 58 59 59 

 Concord 330131007 66 64 68 65 

 Keene 330050007 63 62 64 62 

 Laconia 330012004 62 62 64 60 

 Lebanon 330090010 60 59 61 59 

 Londonderry 330150018 -- -- -- 69 

 Manchester 330110020 -- 60 63 -- 

 Miller State Park 330115001 70 72 77 62 

 Mt. Washington Summit 330074001 69 68 73 67 

 Nashua 330111011 66 66 67 65 

 Portsmouth 330150014 67 70 66 64 

 Rye - Odiorne 330150016 67 68 66 66 

Areas of Influence to Regional Monitors with Design Values 

Greater than 75 ppb in Massachusetts and Rhode Island 

NHDES performed airflow back-trajectory analyses for all monitors that exceeded the ozone NAAQS 

during either of the most recent two design value periods (2008-2010 and 2009-2011). There are no 

monitors in New Hampshire, Maine, or Vermont with design values that fall into this category, but there 

are two in Massachusetts (Martha’s Vineyard and Worcester) and one in Rhode Island (Narragansett) that 

qualify. For this analysis, back-trajectories were modeled for any day that one of the three identified 

monitors exceeded 75 ppb during 2009, 2010, or 2011. 

NHDES used the National Oceanic and Atmospheric Administration (NOAA)’s Air Resources 

Laboratory HYSPLIT (HYbrid Single-Particle Lagrangian Integrated Trajectory) model. This is a 

computer model designed to create and map trajectories using gridded historical meteorological data. All 

trajectories produced by NHDES begin 72 hours before a measured value exceeds 75ppb. 

Each set of figures show that none of the airflow back trajectories pass over New Hampshire prior to 

arriving at Martha’s Vineyard, Worcester, or Narragansett during high ozone days. Instead the 

trajectories show a strong influence from the southern portion of the Northeast Urban Corridor. Since 

none of these trajectories pass over New Hampshire and because New Hampshire’s ozone levels are 

safely below the 75 ppb NAAQS, it can be concluded that New Hampshire does not contribute to any of 

these exceedances in southeastern Massachusetts and Rhode Island and further supports the concept that 

these areas are in a different airshed from New Hampshire. 
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New Hampshire Monitoring Values and Trajectories October 27, 2011

 

Back Trajectories for Days Greater than 75 ppb at Worcester, MA 
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New Hampshire Monitoring Values and Trajectories October 27, 2011

 
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New Hampshire Monitoring Values and Trajectories October 27, 2011

 
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New Hampshire Monitoring Values and Trajectories October 27, 2011

 

Back Trajectories for Days Greater than 75 ppb at Martha’s Vineyard, MA
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New Hampshire Monitoring Values and Trajectories October 27, 2011

 
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New Hampshire Monitoring Values and Trajectories October 27, 2011

 
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New Hampshire Monitoring Values and Trajectories October 27, 2011

 
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New Hampshire Monitoring Values and Trajectories October 27, 2011

 
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New Hampshire Monitoring Values and Trajectories October 27, 2011

 

Back Trajectories for Days Greater than 75 ppb at Narragansett, RI
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New Hampshire Monitoring Values and Trajectories October 27, 2011

 
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New Hampshire Monitoring Values and Trajectories October 27, 2011