Tropospheric ozone variability over the Iberian Peninsula

To study tropospheric ozone variability over the Iberian Peninsula (IP), NASA Langley TOR data have been analyzed for the 1979–2005 period. The maximum tropospheric ozone concentration over the entire IP was found in June (∼41 DU) and a minimum in December (∼29 DU). However the maximum tropospheric ozone concentration was found over West Atlantic Coast (WAC) (∼44 DU), followed by Mediterranean Coast (MC) (∼42 DU), North Atlantic Coast (NAC) (∼41 DU), Central Iberian Peninsula (CIP) (∼40 DU) and Pyrenees Mountain Range (PMR) (∼39 DU) during June-July. The high concentration of tropospheric ozone in July over the Atlantic Ocean near IP is due to the presence of Azores anticyclone and related photochemistry and dynamics, and affects the observed higher tropospheric ozone concentration over WAC zone. Strong seasonal cycle in tropospheric ozone concentration has been observed with large variation over NAC (∼49%), followed by WAC (∼48%) and MC (∼41%) compared to CIP and PMR (∼38%) zones. When the data are compared over the IP for the two periods (1979–1993 and 1997–2005), a systematic increase in the number of months with higher tropospheric ozone concentration has been observed during the second period with respect to the first. These increases are almost 8% to 24% over NAC, 6% to 17% over WAC, 5% to 24% over CIP, 6% to 23% over MC and 13% to 18% over PMR, zones. It has been observed that topography, climatology and population density distribution plays a crucial role in the variability of tropospheric ozone concentration over the IP.