17:15 〜 19:15
[AAS06-P01] Improvement and Issues in Representation of Stratospheric Field in JRA-3Q Reanalysis
キーワード：再解析、成層圏、気象庁第3次長期再解析、気象庁55年長期再解析、気温、水蒸気
The Japan Meteorological Agency (JMA) has conducted the third Japanese global atmospheric reanalysis named Japanese Reanalysis for Three Quarters of a Century (JRA-3Q, Kosaka et al. 2024) using the JMA operational data assimilation system that has been upgraded and improved since the Japanese 55-year Reanalysis (JRA-55, Kobayashi et al. 2015) was conducted. In JRA-3Q data assimilation system, vertical levels are increased up to 100 layers, top level of the system is 0.01 hPa, and non-orographic gravity wave parameterization based on Scinocca (2003) are implemented. In addition, GNSS radio occultation, bending angle is assimilated up to 60 km.
JRA-55 has a large warm bias in the lower mesosphere and cold bias in the upper stratosphere, although it reduced biases in lower stratosphere (Harada et al. 2016). In addition, he recently conducted SPARC Reanalysis Intercomparison Project (Fujiwara et al. 2017) critically assessed the stratospheric water vapor in JRA-55, and concluded that it was excessive and not recommended for use in scientific studies (Davis et al. 2017).
Therefore, we have conducted quality assessment of stratospheric field in JRA-3Q using a dataset based on satellite observation, including the lower mesosphere. The Earth Observing System Microwave Limb Sounder (MLS), onboard the National Aeronautics and Space Administration Aura satellite launched in July 2004 (Aura MLS), has been measuring temperatures, several atmospheric species, cloud ice, and geopotential heights to provide information about the earth’s upper troposphere, stratosphere, and mesosphere (Waters et al. 2006).
With regarding to water vapor, we found that JRA-3Q greatly reduced wet bias observed mainly in mid and high latitudes in JRA-55 as mentioned above. In addition, a comparison of temperature with Aura MLS reveals that JRA-3Q reduces cold bias in the upper stratosphere and warm bias from equatorial regions to mid-latitudes. In particular, the root mean square error has generally been reduced by half in the region. In the high latitudes of the lower mesosphere, JRA-55 showed a cold bias in the winter hemisphere, while JRA-3Q shows an opposite warm bias in the region. In the upper 0.5 hPa layer at high latitudes of the winter hemisphere, the longwave radiative process of JRA-3Q has a rather stronger cooling than that of JRA-55. However, the adiabatic heating due to dynamical processes surpasses the effect of longwave radiation.
Reference:
Davis, S. M., M. I. Hegglin, M. Fujiwara, R. Dragani, Y. Harada, C. Kobayashi, C. Long, G. L. Manney, E. R. Nash, G. L. Potter, S. Tegtmeier, T. Wang, K. Wargan, and J. S. Wright, 2017: Assessment of upper tropospheric and stratospheric water vapor and ozone in reanalyses as part of S-RIP. Atmos. Chem. Phys., 17, 12743–12778.
Fujiwara, M., and Coauthors, 2017: Introduction to the SPARC Reanalysis Intercomparison Project (S-RIP) and overview of the reanalysis systems. Atmos. Chem. Phys., 17, 1417–1452.
Harada, Y., and Coauthors, 2016: The JRA-55 reanalysis: Representation of atmospheric circulation and climate variability. J. Meteor. Soc. Japan, 94, 269–302.
Kobayashi, S., and Coauthors, 2015: The JRA-55 reanalysis: General specifications and basic characteristics. J. Meteor. Soc. Japan, 93, 5-48.
Kosaka, Y., and Coauthors, 2024: The JRA-3Q reanalysis. J. Meteor. Soc. Japan, 102, 49-109.
Scinocca, J. F., 2003: An accurate spectral nonorographic gravity wave drag parameterization for general circulation models. J. Atmos. Sci., 60, 667–682.
Waters, J. W., and Coauthors 2006: The Earth Observing System Microwave Limb Sounder (EOS MLS) on the Aura satellite. IEEE Trans. Geosci. Remote Sens., 44, 1075–1092.
JRA-55 has a large warm bias in the lower mesosphere and cold bias in the upper stratosphere, although it reduced biases in lower stratosphere (Harada et al. 2016). In addition, he recently conducted SPARC Reanalysis Intercomparison Project (Fujiwara et al. 2017) critically assessed the stratospheric water vapor in JRA-55, and concluded that it was excessive and not recommended for use in scientific studies (Davis et al. 2017).
Therefore, we have conducted quality assessment of stratospheric field in JRA-3Q using a dataset based on satellite observation, including the lower mesosphere. The Earth Observing System Microwave Limb Sounder (MLS), onboard the National Aeronautics and Space Administration Aura satellite launched in July 2004 (Aura MLS), has been measuring temperatures, several atmospheric species, cloud ice, and geopotential heights to provide information about the earth’s upper troposphere, stratosphere, and mesosphere (Waters et al. 2006).
With regarding to water vapor, we found that JRA-3Q greatly reduced wet bias observed mainly in mid and high latitudes in JRA-55 as mentioned above. In addition, a comparison of temperature with Aura MLS reveals that JRA-3Q reduces cold bias in the upper stratosphere and warm bias from equatorial regions to mid-latitudes. In particular, the root mean square error has generally been reduced by half in the region. In the high latitudes of the lower mesosphere, JRA-55 showed a cold bias in the winter hemisphere, while JRA-3Q shows an opposite warm bias in the region. In the upper 0.5 hPa layer at high latitudes of the winter hemisphere, the longwave radiative process of JRA-3Q has a rather stronger cooling than that of JRA-55. However, the adiabatic heating due to dynamical processes surpasses the effect of longwave radiation.
Reference:
Davis, S. M., M. I. Hegglin, M. Fujiwara, R. Dragani, Y. Harada, C. Kobayashi, C. Long, G. L. Manney, E. R. Nash, G. L. Potter, S. Tegtmeier, T. Wang, K. Wargan, and J. S. Wright, 2017: Assessment of upper tropospheric and stratospheric water vapor and ozone in reanalyses as part of S-RIP. Atmos. Chem. Phys., 17, 12743–12778.
Fujiwara, M., and Coauthors, 2017: Introduction to the SPARC Reanalysis Intercomparison Project (S-RIP) and overview of the reanalysis systems. Atmos. Chem. Phys., 17, 1417–1452.
Harada, Y., and Coauthors, 2016: The JRA-55 reanalysis: Representation of atmospheric circulation and climate variability. J. Meteor. Soc. Japan, 94, 269–302.
Kobayashi, S., and Coauthors, 2015: The JRA-55 reanalysis: General specifications and basic characteristics. J. Meteor. Soc. Japan, 93, 5-48.
Kosaka, Y., and Coauthors, 2024: The JRA-3Q reanalysis. J. Meteor. Soc. Japan, 102, 49-109.
Scinocca, J. F., 2003: An accurate spectral nonorographic gravity wave drag parameterization for general circulation models. J. Atmos. Sci., 60, 667–682.
Waters, J. W., and Coauthors 2006: The Earth Observing System Microwave Limb Sounder (EOS MLS) on the Aura satellite. IEEE Trans. Geosci. Remote Sens., 44, 1075–1092.