Aircraft Observation of CO2, CO, O3 and H2 over the North Pacific during the PACE-7 Campaign

Abstract

A B S T R A C TAircraft observation under the Pacific Atmospheric Chemistry Experiment (PACE) program was performed from February 13 to 21, 2000 to examine in detail the distributions of CO 2 in the free troposphere between 5 and 11 km. Continuous measurements of CO 2 mixing ratios were made using an on-board measuring system over the northern North Pacific between Nagoya, Japan and Anchorage, Alaska, and the western North Pacific between Nagoya and Saipan. Other trace gases, such as CO and O 3 , were also observed using continuous measuring systems at the same time. CO 2 over the northern Pacific (35 • N and higher) showed highly variable mixing ratios, ranging from 374 ppm in the upper troposphere to 366 ppm in the lowermost stratosphere. This highly variable distribution of CO 2 was quite similar to that of CO, but the relationship between CO 2 and O 3 showed a strong negative correlation. These results indicated that the exchange process between the stratosphere and the troposphere significantly influences the large CO 2 variation. On the other hand, the CO 2 over the western North Pacific to the south of Japan showed no significant variation in the upper troposphere at 11 km but a relatively larger variability at 5 km. The CO 2 enhancement at lower altitudes coincided with the CO elevation due to the intrusion of a polluted air mass. Trajectory analysis indicated that the Asian continental outflow perturbed the CO 2 distributions over the western Pacific. Very low mixing ratios of O 3 of less than 20 ppb were distributed in the latitude band of 15-30 • N at 11 km, reflecting the effects of transport from the equatorial region.

Airborne in-situ measurements of vertical, seasonal and latitudinal distributions of carbon dioxide over Europe

“…The near-continual decrease of CO 2 with altitude in fall and winter, as well as the steady increase during summer could also be caused by the influence of stratospheretroposphere transport (STT) on the vertical profiles (Sawa et al, 2004;Shia et al, 2006). In the fall and winter seasons the enhanced downward transport (compared to the summer season) of aged CO 2 -poor air from the stratosphere yields lower values of CO 2 in the upper troposphere relative to the MBL reference ( CO 2 <0).…”

“…Chedin et al, 2003;Buchwitz et al, 2005;Engelen and McNally, 2005;Barclay et al, 2006;Tiwari et al, 2006), measurements of CO 2 in the free troposphere and the lower stratosphere are restricted to a small number of balloon-and airborne measurement campaigns (e.g. Pearman and Beardsmore, 1984;Nakazawa et al, 1991;Matsueda and Inoue, 1996;Anderson et al, 1996;Boering et al, 1996;Vay et al, 1999;Zahn et al, 1999;Matsueda et al, 2002;Machida et al, 2003;Aoki et al, 2003;Sawa et al, 2004;Lin et al, 2006).…”

Error correlation between CO&lt;sub&gt;2&lt;/sub&gt; and CO as constraint for CO&lt;sub&gt;2&lt;/sub&gt; flux inversions using satellite data

“…If model transport errors for CO 2 and CO are correlated, then CO has the potential to provide additional information to improve inverse CO 2 flux estimates (Palmer et al, 2006). Strong correlations between CO 2 and CO concentrations are consistently seen in atmospheric observations at the surface (Potosnak et al, 1999;Gamnitzer et al, 2006) and from aircraft (Conway et al, 1993;Sawa et al, 2004;Schmitgen et al, 2004;Suntharalingam et al, 2004;Takegawa et al, 2004;Palmer et al, 2006). These correlations result from common source/sink regions, common large-scale latitudinal gradients, and common transport.…”

Number-size Distributions of Aerosol Particles in the Free Troposphere over the Northwestern Pacific Ocean-Influence of Asian Outflow and Tropical Air Transport

“…Air temperature and dew point temperature were measured using Rosemount temperature sensor and EGG dew point sensor, respectively. Mixing ratios of CO, O 3 and other trace gases observed in this campaign were summarized in Sawa et al (2004). Figure 3 shows the vertical profiles of aerosol concentrations (3a), air and dew point temperature (3b), and mixing ratio of SO 2 (3c) observed over Naha (flight No.…”