|
|
Hokkaido University Collection of Scholarly and Academic Papers >
Graduate School of Environmental Science / Faculty of Environmental Earth Science >
Peer-reviewed Journal Articles, etc >
Wave activity in the tropical tropopause layer in seven reanalysis and four chemistry climate model data sets
| Title: | Wave activity in the tropical tropopause layer in seven reanalysis and four chemistry climate model data sets |
| Authors: | Fujiwara, M. Browse this author →KAKEN DB | | Suzuki, J. Browse this author | | Gettelman, A. Browse this author | | Hegglin, M. I. Browse this author | | Akiyoshi, H. Browse this author | | Shibata, K. Browse this author |
| Issue Date: | 26-Jun-2012 |
| Publisher: | American Geophysical Union |
| Journal Title: | Journal of Geophysical Research, Atmospheres |
| Volume: | 117 |
| Start Page: | D12105 |
| Publisher DOI: | 10.1029/2011JD016808 |
| Abstract: | Sub-seasonal variability including equatorial waves significantly influence the dehydration and transport processes in the tropical tropopause layer (TTL). This study investigates the wave activity in the TTL in 7 reanalysis data sets (RAs; NCEP1, NCEP2, ERA40, ERA-Interim, JRA25, MERRA, and CFSR) and 4 chemistry climate models (CCMs; CCSRNIES, CMAM, MRI, and WACCM) using the zonal wave number-frequency spectral analysis method with equatorially symmetric-antisymmetric decomposition. Analyses are made for temperature and horizontal winds at 100 hPa in the RAs and CCMs and for outgoing longwave radiation (OLR), which is a proxy for convective activity that generates tropopause-level disturbances, in satellite data and the CCMs. Particular focus is placed on equatorial Kelvin waves, mixed Rossby-gravity (MRG) waves, and the Madden-Julian Oscillation (MJO). The wave activity is defined as the variance, i.e., the power spectral density integrated in a particular zonal wave number-frequency region. It is found that the TTL wave activities show significant difference among the RAs, ranging from ∼0.7 (for NCEP1 and NCEP2) to ∼1.4 (for ERA-Interim, MERRA, and CFSR) with respect to the averages from the RAs. The TTL activities in the CCMs lie generally within the range of those in the RAs, with a few exceptions. However, the spectral features in OLR for all the CCMs are very different from those in the observations, and the OLR wave activities are too low for CCSRNIES, CMAM, and MRI. It is concluded that the broad range of wave activity found in the different RAs decreases our confidence in their validity and in particular their value for validation of CCM performance in the TTL, thereby limiting our quantitative understanding of the dehydration and transport processes in the TTL. |
| Rights: | ©2012 American Geophysical Union |
| Type: | article |
| URI: | http://hdl.handle.net/2115/50989 |
| Appears in Collections: | 環境科学院・地球環境科学研究院 (Graduate School of Environmental Science / Faculty of Environmental Earth Science) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)
|
Submitter: 藤原 正智
|
