المؤلفون: Wang, Lu, Li, Tim, Maloney, Eric, Wang, Bin

المصدر: Journal of Climate. May2017, Vol. 30 Issue 10, p3743-3769. 27p. 1 Diagram, 1 Chart, 12 Graphs, 7 Maps.

مصطلحات موضوعية: *MADDEN-Julian oscillation, *ELASTIC wave propagation, *GENERAL circulation model, *CONVECTION (Meteorology), *VELOCITY

مستخلص: This study investigates the fundamental causes of differences in the Madden-Julian oscillation (MJO) eastward propagation among models that participated in a recent model intercomparison project. These models are categorized into good and poor groups characterized by prominent eastward propagation and nonpropagation, respectively. Column-integrated moist static energy (MSE) budgets are diagnosed for the good and the poor models. It is found that a zonal asymmetry in the MSE tendency, characteristic of eastward MJO propagation, occurs in the good group, whereas such an asymmetry does not exist in the poor group. The difference arises mainly from anomalous vertical and horizontal MSE advection. The former is attributed to the zonal asymmetry of upper-midtropospheric vertical velocity anomalies acting on background MSE vertical gradient; the latter is mainly attributed to the asymmetric zonal distribution of low-tropospheric meridional wind anomalies advecting background MSE and moisture fields. Based on the diagnosis above, a new mechanism for MJO eastward propagation that emphasizes the second-baroclinic-mode vertical velocity is proposed. A set of atmospheric general circulation model experiments with prescribed diabatic heating profiles was conducted to investigate the causes of different anomalous circulations between the good and the poor models. The numerical experiments reveal that the presence of a stratiform heating at the rear of MJO convection is responsible for the zonal asymmetry of vertical velocity anomaly and is important to strengthening lower-tropospheric poleward flows to the east of MJO convection. Thus, a key to improving the poor models is to correctly reproduce the stratiform heating. The roles of Rossby and Kelvin wave components in MJO propagation are particularly discussed. [ABSTRACT FROM AUTHOR]

المؤلفون: PREVIDI, MICHAEL¹ mprevidi@ldeo.columbia.edu, SMITH, KAREN L.^1,2,3, POLVANI, LORENZO M.^1,2,3

المصدر: Journal of Climate. Sep2013, Vol. 26 Issue 17, p6406-6418. 13p. 2 Charts, 6 Graphs, 2 Maps.

مصطلحات موضوعية: *IONOSPHERIC electromagnetic wave propagation, *ANTARCTIC research stations, *ENERGY budget (Geophysics), *SOUTHERN oscillation, *ANTARCTIC oscillation, *SURFACE temperature

مستخلص: The authors present a new, observationally based estimate of the atmospheric energy budget for the Antarctic polar cap (the region poleward of 70°S). This energy budget is constructed using state-of-the-art reanalysis products from ECMWF [the ECMWF Interim Re-Analysis (ERA-Interim)] and Clouds and the Earth's Radiant Energy System (CERES) top-of-atmosphere (TOA) radiative fluxes for the period 2001-10. The climatological mean Antarctic energy budget is characterized by an approximate balance between the TOA net outgoing radiation and the horizontal convergence of atmospheric energy transport, with the net surface energy flux and atmospheric energy storage generally being small in comparison. Variability in the energy budget on intraseasonal-to-interannual time scales bears a strong signature of the southern annular mode (SAM), with El Nino-Southern Oscillation (ENSO) having a smaller impact. The energy budget framework is shown to be a useful alternative to the SAM for interpreting surface climate variability in the Antarctic region. [ABSTRACT FROM AUTHOR]

المؤلفون: DeMott, Charlotte A., Stan, Cristiana, Randall, David A.

المصدر: Journal of Climate. Mar2013, Vol. 26 Issue 6, p1973-1992. 20p. 13 Graphs.

مصطلحات موضوعية: *RADIO wave propagation, *OSCILLATIONS, *MONSOONS, *TROPOSPHERE, *BAROTROPIC equation, *VORTEX motion

مصطلحات جغرافية: ARABIAN Sea

مستخلص: Mechanisms for the northward propagation (NP) of the boreal summer intraseasonal oscillation (BSISO) and associated Asian summer monsoon (ASM) are investigated using data from the interim ECMWF Re-Analysis (ERA-Interim, herein called ERAI) and the superparameterized Community Climate System Model (SP-CCSM). Analyzed mechanisms are 1) destabilization of the lower troposphere by sea surface temperature anomalies, 2) boundary layer moisture advection, and boundary layer convergence associated with 3) SST gradients and 4) barotropic vorticity anomalies. Mechanism indices are regressed onto filtered OLR anomaly time series to study their relationships to the intraseasonal oscillation (ISO) and to equatorial Rossby (ER) waves. Northward propagation in ERAI and SP-CCSM is promoted by several mechanisms, but is dominated by boundary layer moisture advection and the barotropic vorticity effect. SST-linked mechanisms are of secondary importance but are nonnegligible. The magnitudes of NP mechanisms vary from the Indian Ocean to the west Pacific Ocean, implying that NP is accomplished by different mechanisms across the study area. SP-CCSM correctly simulates observed NP mechanisms over most of the ASM domain except in the Arabian Sea during the early stages of the monsoon life cycle. Reduced NP in the Arabian Sea arises from weaker-than-observed easterly shear, reducing the effectiveness of the barotropic vorticity mechanism. The ability of SP-CCSM to correctly simulate NP mechanisms in other regions results from the model's ability to simulate reasonable mean wind and moisture fields, a realistic spectrum of variability, and the capability of convection to respond to boundary layer changes induced by large-scale NP mechanisms. [ABSTRACT FROM AUTHOR]

المؤلفون: Park, Hyo-Seok, Lintner, Benjamin R., Boos, William R., Seo, Kyong-Hwan

المصدر: Journal of Climate, 2015 Nov 01. 28(21), 8450-8465.

الوصول الحر: https://www.jstor.org/stable/26195702Test

المؤلفون: Li, Xichen, Holland, David M., Gerber, Edwin P., Yoo, Changhyun

المصدر: Journal of Climate, 2015 Oct . 28(20), 8151-8164.

الوصول الحر: https://www.jstor.org/stable/26196050Test

المؤلفون: Zhao, Sen, Li, Jianping, Li, Yanjie

المصدر: Journal of Climate, 2015 Oct 01. 28(19), 7437-7456.

الوصول الحر: https://www.jstor.org/stable/26196007Test

المؤلفون: Sun, Lantao, Deser, Clara, Tomas, Robert A.

المصدر: Journal of Climate, 2015 Oct 01. 28(19), 7824-7845.

الوصول الحر: https://www.jstor.org/stable/26196028Test

المؤلفون: Martineau, Patrick, Son, Seok-Woo

المصدر: Journal of Climate, 2015 Sep . 28(18), 7347-7370.

الوصول الحر: https://www.jstor.org/stable/26196001Test

المؤلفون: Wu, Liang, Wen, Zhiping, Wu, Renguang

المصدر: Journal of Climate, 2015 Sep . 28(18), 7108-7127.

الوصول الحر: https://www.jstor.org/stable/26195987Test

المؤلفون: Ren, Xuejuan, Yang, Dejian, Yang, Xiu-Qun

المصدر: Journal of Climate, 2015 Sep 01. 28(17), 6799-6822.

الوصول الحر: https://www.jstor.org/stable/26196072Test