HR: 0800h
AN: A51D-0105    [Abstracts]
TI: Hot days and warm nights: Influence of climate change on diurnal variation of O₃ and CO₂ at Barrow, Alaska
AU: Lal, S
EM: shyam@prl.ernet.in
AF: Physical Research Laboratory, Navrangpura, Ahmedabad, Guj 380009 India
AU: Jaffe, D
EM: djaffe@u.washington.edu
AF: University of Washington Bothell, 18115 Campus Way NE, Bothell, WA 98011 United States
AU: Oltmans, S J
EM: Samuel.J.Oltmans@noaa.gov
AF: NOAA Climate Monitoring and Diagnostics Laboratory, 325 Broadway, Boulder, CO 80305 United States
AU: Tans, P
EM: Pieter.Tans@noaa.gov
AF: NOAA Climate Monitoring and Diagnostics Laboratory, 325 Broadway, Boulder, CO 80305 United States
AU: Mefford, T
EM: Thomas.Mefford@noaa.gov
AF: NOAA Climate Monitoring and Diagnostics Laboratory, 325 Broadway, Boulder, CO 80305 United States
AU: * Chand, D
EM: dchand@uwb.edu
AF: University of Washington Bothell, 18115 Campus Way NE, Bothell, WA 98011 United States
AB: Measurements at Barrow, Alaska over the past 25 years (for the time periods 1978-87 and 1994-2003) show a significant warming of about 0.8 °C and a change in the diurnal temperature pattern. The mean summer Diurnal Temperature Range (DTR) has gone from 2.2 °C to 2.0 °C over this period. Additionally, the diurnal pattern of several key trace gases has also changed over the same time. For O₃ the Diurnal Range (DR) has changed from 1.3 part per billion (ppb) to 1.0 ppb and for CO₂ from 970 ppb to 760 ppb. Both O₃ and temperature have increased faster in night than day time during this period. We speculate that these changes are most likely due to change in mixing layer height due to a greater increase in nighttime temperatures, compared to day time temperatures. Warmer nighttime temperatures will likely increase the thickness of the boundary layer (BL) and are consistent with the trace gas trends we observe. For O₃ a thicker nighttime BL will reduce surface deposition and increase the observed nighttime concentrations. For CO₂, a thicker nighttime BL will result in greater dilution of nighttime surface emissions of CO₂. Alternatively, changes in cloud cover could also play a role. These observations suggest an important linkage between climate change and trace gas concentrations. They also imply an important caveat for interpretation of trace gas changes from surface observations.
DE: 0365 Troposphere: composition and chemistry
DE: 0368 Troposphere: constituent transport and chemistry
DE: 0490 Trace gases
DE: 3305 Climate change and variability (1616, 1635, 3309, 4215, 4513)
DE: 3307 Boundary layer processes
SC: Atmospheric Sciences [A]
MN: Fall Meeting 2005