# Presentation: 263322

## A connection between tropical storms and pollution events? 

- A connection between tropical storms and pollution events?

- Three intriguing incidences of increased ground-level ozone and particulate matter concentrations in Atlanta, GA

**Carlos A. Cardelino**
**Michael E. Chang**
**Bill B. Murphey**

## Climatological View

## Three interesting events

**Tropical storm Allison**
**June, 2001**

**Hurricane Gabrielle**
**September, 2001**

**Hurricane Dennis**
**July, 2005**

## Single day increase: O3 and PM2.5

- Gabrielle

- Allison

- Dennis

- Gabrielle
- Dennis

- Allison

## Three events: Precipitation

**Allison**

**Gabrielle**

**Dennis**

## Three events: Wind speed

**Allison**

**Gabrielle**

**Dennis**

## Three events: Temperature

**Allison**

**Gabrielle**

**Dennis**

## Atlanta Ozone Forecast Performance 1999-2005

**Atlanta Ozone Forecast Performance 1999-2005**

- 2002

- 2000

- 1999

- 2001

- 8-hr Average Ozone (ppbv)

- 2003

- 2004

- 2005

- Date

## Atlanta Ozone Forecast Performance 1999-2005

- 2002

- 2001

- 2000

- 1999

- False
- Positive

- False
- Negative

- Observed Peak 8-hr Average Ozone (ppbv)

- Predicted Peak 8-hr Average Ozone (ppbv)

**Atlanta Ozone Forecast Performance 1999-2005**

- 2003

- 2004

- 2005

## Forecasting exceedances of the NAAQS is very important. 

From 1999-2005, the Atlanta area experienced 211 days between May 1 and September 30 when ozone pollutant concentrations were “Code Orange” or higher.

160 of the 211 exceedances were forecasted (76%). 

- From 1999-2005, the Atlanta area experienced 211 days between May 1 and September 30 when ozone pollutant concentrations were “Code Orange” or higher.
- 160 of the 211 exceedances were forecasted (76%).

**Atlanta Ozone Forecast Performance 1999-2005**

## Missing forecasting an exceedance is very bad.)

51 of the 211 exceedances were missed (24%).

Most misses could be reconciled in retrospect (e.g. bad forecast meteorology, poor recognition by forecasters, timing uncertainties, etc...) 

A few misses remained unexplained...           until now...maybe...

- 51 of the 211 exceedances were missed (24%).
- Most misses could be reconciled in retrospect (e.g. bad forecast meteorology, poor recognition by forecasters, timing uncertainties, etc...)
- A few misses remained unexplained...           until now...maybe...

**Atlanta Ozone Forecast Performance 1999-2005**

## Unexplained Missed Ozone Exceedances in Metro Atlanta

|  | Peak 8-hour Avg Ozone (ppbv) |  |
| --- | --- | --- |
| Date | Predicted | Observed |
| June 13, 2001 | 44 | 89 |
| September 13, 2001 | 60 | 85 |
| July 8, 2005 | 54 | 88 |

## Atlanta Ozone Forecast Performance 2001

- 2001

- June 13
-    predicted 44 ppb
-    observed 89 ppb

- Observed Ozone (ppb)

- Predicted Ozone (ppb)

**Atlanta Ozone Forecast Performance 2001**

- ...and the worst forecast of the year award goes to...

## Surface data plot for 12Z 12 June 2001

**Surface data plot for 12Z 12 June 2001**

## Surface data plot for 12Z 13 June 2001

**Surface data plot for 12Z 13 June 2001**

## Surface data plot for 12Z 14 June 2001

**Surface data plot for 12Z 14 June 2001**

## Best track positions for Tropical Storm Allison, 5-17 June 2001 (National Hurricane Center)

## Single Day Increase in Peak Daily 8-hour average Ozone Concentration, Atlanta Metro, 1987-2005

- O3 = O3tpeak –  O3t-1peak

- -60	    -40	        -20	             0	 20	     40	        60

- 100
- 80
- 60
- 40
- 20
- 0

- Number of Events

- O3 (ppb)

- June 13, 2001

## The State of Our Understanding about Tropical Storms and their Impact on Air Quality in Atlanta (c. June 2001)

**Ozone (ppb)**

- “I'm stumped for today. Tomorrow is a total guess too.”

- “Some clearing tomorrow as remains of Allison moves into Carolinas late today. Partly cloudy skies with some instability will give chance for thunderstorms. This should hold down formation and accumulation of ozone and keep us ‘green.’”

- “Remnants of Allison keep us green today and tomorrow.”

- Individual
- Forecasters

- Observed

- Team

## Before and After

## 850 mb Streamlines and 500 mb Height (dm)

- 21 UTC 13 JUN 2001

## 850 mb Streamlines and Temperature (degC)

- 21 UTC 13 JUN 2001

## 850 mb Streamlines and Relative Humidity (%)

- 21 UTC 13 JUN 2001

## Slide 24

## How TS Allison might have affected air quality in Atlanta

- Outflow from storm created area of strong subsidence and compression which increased local photochemical production and accumulation; or
- 180° wind direction change with passing of TS Allison led to recirculation and accumulation of multiple days’ pollutants; or
- TS Allison enabled long range transport of pollutants and  pollutant precursors; or
- All of the above.

- A few hypotheses to consider:

## Conclusions

- Ozone and PM2.5 pollutant concentrations in Atlanta were elevated on June 13, 2001 not in spite of TS Allison, but because of TS Allison.
- Hurricanes Gabrielle (2001), Dennis (2005), and Rita (2005) also appear to have led to increased ozone and PM2.5 concentrations in the Atlanta area (not shown).
- Tropical Storms and Hurricanes do warrant special concern by air quality forecasters, and may warrant special consideration by regulators during NAAQS attainment deliberations.

## Stratospheric intrusions?