Eriko Nishimoto

Current status of level 2 product of Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES)

New level 2 products v2.0 of JEM/SMILES are scheduled to be released in Sep., 2011. This will be the first publicreleased version. In pre-released product v1.3, positive bias of retrieved temperature in the stratosphere was the largest issue since temperature is basic parameter which characterizes the atmospheric structure. The new product use latest L1B 007 which includes gain nonlinearity effect of receivers, bias of temperature in upper stratosphere is suppressed. In addition, we stopped temperature retrieval above 40km and refer MLS temperature product with applying migrating tidal model. HCl profiles in mesosphere become constant, which supports this temperature processing.

Influence of the Stratospheric Quasi-Biennial Oscillation on the Madden–Julian Oscillation during Austral Summer

AbstractInfluence of the stratospheric quasi-biennial oscillation (QBO) on the Madden–Julian oscillation (MJO) and its statistical significance are examined for austral summer (DJF) in neutral ENSO events during 1979–2013. The amplitude of the OLR-based MJO index (OMI) is typically larger in the easterly phase of the QBO at 50 hPa (E-QBO phase) than in the westerly (W-QBO) phase. Daily composite analyses are performed by focusing on phase 4 of the OMI, when the active convective system is located over the eastern Indian Ocean through the Maritime Continent. The composite OLR anomaly shows a larger negative value and slower eastward propagation with a prolonged period of active convection in the E-QBO phase than in the W-QBO phase. Statistically significant differences of the MJO activities between the QBO phases also exist with dynamical consistency in the divergence of horizontal wind, the vertical wind, the moisture, the precipitation, and the 100-hPa temperature. A conditional sampling analysis is also...

Vertical Momentum Transports Associated with Moist Convection and Gravity Waves in a Minimal Model of QBO-like Oscillation

AbstractA self-sustained oscillation dynamically analogous to the equatorial quasi-biennial oscillation (QBO) was obtained as a radiative–moist-convective quasi-equilibrium state in a minimal model of the stratosphere–troposphere coupled system, which is a two-dimensional cloud-system-resolving nonhydrostatic model with a periodic lateral boundary condition. The QBO-like oscillation shows downward propagation of the zonal mean signals in the stratosphere. In addition, in the troposphere there are periodic variations associated with the QBO-like oscillation, including organized features of moist-convective systems characterized as squall-line- or back-building-type precipitation patterns. Details of the momentum budget variation are examined to study the stratosphere–troposphere dynamical coupling associated with the QBO-like oscillation. The vertical flux of horizontal momentum is separated into three contributions of convective momentum transport (CMT) and momentum transports by upward- and downward-prop...

Downward Influence of QBO-Like Oscillation on Moist Convection in a Two-Dimensional Minimal Model Framework

AbstractThe influence of the quasi-biennial oscillation (QBO)-like oscillation on moist convection is examined using the two-dimensional minimal model framework of Yoden et al. with two series of parameter sweep experiments: model-top experiments with varying model height and low-level nudging experiments with reduced zonal-mean zonal wind toward zero from the surface to a certain level. The QBO-like oscillation in the mean zonal wind is a robust feature obtained in all the experiments, including low-top cases in which only the tropospheric portion is retained. The zonal-mean precipitation is modulated with a half period of the mean zonal wind oscillation in the model-top experiments, and a positive correlation exists between the precipitation intensity and the vertical shear of the mean zonal wind near the surface. The precipitation modulation is weakened with a nudging of the low-level mean zonal wind but appears again in the cases with the low-level nudging in the middle and lower troposphere. There is...