Characteristic of Atmospheric Fine Structure of Ozone, Carbon Monoxide, and Humidity During PEACE in Winter and Spring 2002

Ozone, carbon monoxide, reactive nitrogen species, nonmethane hydrocarbons, aerosols, water vapor, and carbon dioxide were measured on board Gulfstream II aircraft during the Pacific Exploration of Asian Continental Emission (PEACE) phase A (January 2002) and phase B (April and May 2002) over the western Pacific. Water vapor distribution in the upper troposphere and the lower stratosphere is interesting because the measurements in such regions are limited even though water vapor is recognized as an important greenhouse gas. Latitudinal and vertical distributions of water vapor were discussed in terms of atmospheric fine structure, and the in situ water vapor measurements and the model data from ECMWF analyses were compared. Qualitatively the latitudinal and vertical distributions agreed well, but many fine structures were not reproduced in the model due to its coarse resolution in the model. The model tends to underestimate the water vapor mixing ratios, especially when especially when relative humilities over ice are close to 100% or higher. Atmospheric layers were examined using in situ measurements of ozone, carbon monoxide, humidity. Layers were defined as an enhancement relative to local backgrounds, which were determined using a mode-based method [Stoller et al., 1999]. Using ozone, carbon monoxide, and relative humidity, we found 59 layers (0.14 layers/km) in PEACE-A. Stratospheric air and polluted air were the dominant layer sources in PEACE-A.