Event Title
Ozone variations over the Northern subtropical region revealed by ozonesonde observations in Hanoi
Location
East-West Center, University of Hawai'i at Manoa (Honolulu, Hawai'i)
Start Date
18-10-2012 11:50 AM
End Date
18-10-2012 12:10 PM
Document Type
Event
Description
Seasonal and subseasonal variations in the ozone mixing ratio (OMR) are investigated by using continuous seven-year ozonesonde data from Hanoi (21 0 N, 106 0 E), Vietnam. The mean seasonal variations for the seven years show large amplitude at the upper troposphere and lower stratosphere (UTLS) region (10–18 km) and at the lower troposphere (around 3 km) with standard deviations relative to the mean value of about 30% for both regions. In the UTLS region, the seasonal variation in the OMR shows a minimum in winter and a maximum in spring to summer. The variation seems to be caused by the seasonal change in horizontal transport. Low OMR air masses are transported from the equatorial troposphere in winter by the anti-cyclonic flow associated with the equatorial convections, and high OMR air masses are transported from the mid-latitude stratosphere in summer possibly due to tropopause foldings in the UT region and anti-cyclonic circulation associated with the Tibetan High in the LT region. In the lower troposphere, a spring maximum is found at 3 km height. Biomass burning and tropopause foldings are suggested as possible causes of this maximum. Subseasonal variations in the OMR show large amplitude in the UTLS region (at around 15 km) and in the boundary layer (below 1 km) with the relative standard deviations larger than 40%. The OMR variations in the winter UTLS region have a negative correlation with the meridional wind. This relation indicates that the low OMRs observed at Hanoi have been transported from the equatorial region.
Ozone variations over the Northern subtropical region revealed by ozonesonde observations in Hanoi (Powerpoint Slides)
Ozone variations over the Northern subtropical region revealed by ozonesonde observations in Hanoi
East-West Center, University of Hawai'i at Manoa (Honolulu, Hawai'i)
Seasonal and subseasonal variations in the ozone mixing ratio (OMR) are investigated by using continuous seven-year ozonesonde data from Hanoi (21 0 N, 106 0 E), Vietnam. The mean seasonal variations for the seven years show large amplitude at the upper troposphere and lower stratosphere (UTLS) region (10–18 km) and at the lower troposphere (around 3 km) with standard deviations relative to the mean value of about 30% for both regions. In the UTLS region, the seasonal variation in the OMR shows a minimum in winter and a maximum in spring to summer. The variation seems to be caused by the seasonal change in horizontal transport. Low OMR air masses are transported from the equatorial troposphere in winter by the anti-cyclonic flow associated with the equatorial convections, and high OMR air masses are transported from the mid-latitude stratosphere in summer possibly due to tropopause foldings in the UT region and anti-cyclonic circulation associated with the Tibetan High in the LT region. In the lower troposphere, a spring maximum is found at 3 km height. Biomass burning and tropopause foldings are suggested as possible causes of this maximum. Subseasonal variations in the OMR show large amplitude in the UTLS region (at around 15 km) and in the boundary layer (below 1 km) with the relative standard deviations larger than 40%. The OMR variations in the winter UTLS region have a negative correlation with the meridional wind. This relation indicates that the low OMRs observed at Hanoi have been transported from the equatorial region.
