JMSJ, 2015, Vol. 93A (December)
Special Issue on the Coordinated International Field Campaign on the Madden-Julian Oscillation
Riley Dellaripa et al. (2015)
Riley Dellaripa, E. M., and E. D. Maloney, 2015: Analysis of MJO wind-flux feedbacks in the Indian Ocean using RAMA buoy observations. J. Meteor. Soc. Japan, 93A, 1-20.
https://doi.org/10.2151/jmsj.2015-021 Graphical Abstract
- This study examined the relative importance of wind-induced surface flux feedbacks to MJO convective destabilization using two RAMA buoys along the equator at 80.5°E and 90°E.
- Fig. 2 shows that intraseasonal latent heat flux (LHFLX) anomalies are roughly 5-7% of TRMM precipitation anomalies at the buoys. Since moist static energy is exported by vertical motions at roughly 10-20% of precipitation (Yu et al. 1998, Sobel et al. 2014), we conclude that LHFLX are an important, though not sufficient, source of moisture for MJO destabilization.
- Fig. 6 shows that wind variability is the dominant contributor to LHFLX anomalies across MJO events, which highlights the importance of wind-induced fluxes to MJO convection.
Masunaga, H., 2015: Assessment of a satellite-based atmospheric budget analysis method using CINDY2011/DYNAMO/AMIE and TOGA COARE sounding array data.J. Meteor. Soc. Japan, 93A, 21-40.
https://doi.org/10.2151/jmsj.2015-032 Graphical Abstract
- A satellite-based method of moisture and thermal budget analysis is examined in comparison with sounding array observations from CINDY2011/DYNAMO/ AMIE and TOGA COARE.
- The satellite analysis is found to quantitatively reproduce the statistical behaviors of large-scale mean vertical motion, moisture convergence, and moist static energy (MSE) convergence as observed from the sounding arrays (Fig. 1), although individual convective events are heavily spread around the ensemble mean of moisture and MSE convergences in composite space.
- The convective events are broken down into “developing”, “off-centered”, and “passing-by” classes using geostationary infrared measurements in attempt to sort out irrelevant samples that are not representative of convective dynamics. All the three composite classes show qualitatively similar evolutions except for the amplitude of variability, with genuine developing events being greatest in amplitude and passing-by disturbances being weakest.
Takemi, T., 2015: Relationship between cumulus activity and environmental moisture during the CINDY2011/DYNAMO field experiment as revealed from convection-resolving simulations.J. Meteor. Soc. Japan, 93A, 41-58.
https://doi.org/10.2151/jmsj.2015-035 Graphical Abstract
- This study investigates the relationship between cumulus convection and environmental moisture in the tropical Indian Ocean by conducting convection-resolving simulations through the nesting capability with which the innermost domain has the 100-m grid resolution for the cases during the CINDY2011/DYNAMO period.
- The cloud cover whose tops exceed a middle level is shown to sharply increase with the increase in precipitable water vapor over about 55 mm. The increase in relative humidity in a lower layer results in the increase in cloud cover at a level above the humid layer.
- The existence of updraft cores that are less diluted with the environment is demonstrated, and contributes to the moistening of the environmental atmosphere. The updraft cores play a key role in the inter-relationship between cumulus convection and its environment, and are regarded as having a preconditioning influence for the convective initiation of MJO.
Moteki, Q., 2015: Equatorially anti-symmetric features in the initiation processes of the Madden-Julian Oscillation observed in the late October during CINDY2011. J. Meteor. Soc. Japan, 93A, 59-79.
https://doi.org/10.2151/jmsj.2015-040 Graphical Abstract
- The initiation processes of the October-MJO during CINDY2011 that consisted of four distinct convective components are schematically illustrated in Figure 11.
- The equatorially anti-symmetric features of the MJO (Fig. 11b) were due to distinct dynamical features of the four convective components: s-ITCZ (the southern intertropical convergence zone) between 10°S and 0° along the meridional sea surface temperature gradients, n-ITCZ at the southern edge of the high SST above 29°C over the Bay of Bengal, VDAS (vortex disturbance over the Arabian Sea) in association with the zonal SST gradients, and WPDS (westward-propagating diurnal convection originating from Sumatra WPDS).
- A single larger-scale upward motion of the MJO was barotropically formed over the equator as a result of the merging of the four convective components in association with the weakening of the Mascarene High (Fig. 11c) and the propagating of the extratropical cyclone in the Southern Hemisphere (Fig. 11d).
Yokoi et al. (2015)
Yokoi, S., and A. H. Sobel, 2015: Intraseasonal variability and seasonal march of the moist static energy budget over the eastern Maritime Continent during CINDY2011/DYNAMO.J. Meteor. Soc. Japan, 93A, 81-100.
https://doi.org/10.2151/jmsj.2015-041 Graphical Abstract
- Column-integrated moist static energy (MSE) budget analyses reveal that surface heat fluxes and atmospheric radiative heating contribute to the maintenance of the amplitude of the MSE anomaly associated with five Madden-Julian Oscillation (MJO) events passing over the eastern Maritime Continent, the study area.
- The MSE vertical advection, along with the horizontal advection, contributes to the phase progression of the MSE anomaly, which is mainly due to the lower-tropospheric descent after the precipitation and MSE maxima, presumably associated with rain re-evaporation
- Assumption of constant normalized gross moist stability (NGMS) implies an underestimate of the contributing effect of the MSE vertical advection on the phase progression.
Kubota et al. (2015)
Kubota, H., K. Yoneyama, J.-I. Hamada, P. Wu, A. Sudaryanto, and I. B. Wahyono, 2015: Role of maritime continent convection during the preconditioning stage of the Madden-Julian Oscillation observed in CINDY 2011/DYNAMO. J. Meteor. Soc. Japan, 93A, 101-114.
https://doi.org/10.2151/jmsj.2015-050 Graphical Abstract
- The role of Sumatra Island convection over the maritime continent during the preconditioning stage of the Madden-Julian Oscillation (MJO) was investigated using intensive observation data of CINDY2011/DYNAMO and HARIMAU2011.
- Convection was activated over Sumatra Island with diurnal cycle associated with the moist air mass which was originated from a tropical depression generated in South China Sea during the preconditioning stage of the MJO in December 2011 (Fig. 3). Then, two-day period disturbances that propagated westward to the central Indian Ocean were coupled with diurnal cycle of convection over Sumatra Island (Fig. 7).
- When the westward propagating disturbances arrived over the central Indian Ocean, low-level moisture advection was excited associated with westward propagating inertio-gravity waves and moistening was promoted in Gan Island over the central Indian Ocean with a two-day period. After the favorable condition of large-scale convection was established, the MJO was activated in the central Indian Ocean.
Miura et al. (2015)
Miura, H., T. Suematsu, and T. Nasuno, 2015: An ensemble hindcast of the Madden-Julian Oscillation during the CINDY2011/DYNAMO field campaign and influence of seasonal variation of
sea surface temperature. J. Meteor. Soc. Japan, 93A, 115-137.
https://doi.org/10.2151/jmsj.2015-055 Graphical Abstract
- The ensemble hindcast initialized during 12–16 October 2011 is performed using a global cloud-system-resolving model with a horizontal mesh size of 14 km.
- Not only the first but also the second MJO event observed during the CINDY2011/DYNAMO period emerges in the ensemble mean, although the signal of the second MJO is unsatisfactory in each member.
- Data analyses indicate that an MJO favorable environment, in which SST of the southeastern Maritime Continent is higher enough than that of the Indian Ocean, is established in late November to early December.
- We provide a perspective that a certain type of the MJO can be regarded as a transition process, responding to the eastward shift of the region of large-scale positive buoyancy production following the warmer SST.
Seiki et al. (2015)
Seiki, A., M. Nagura, T. Hasegawa, and K. Yoneyama, 2015: Seasonal onset of the Madden-Julian Oscillation and its relation to the southeastern Indian Ocean cooling. J. Meteor. Soc. Japan, 93A, 139-156.
Special Edition on Contributions to Asia Oceania Atmospheric Sciences
https://doi.org/10.2151/jmsj.2015-047 Graphical Abstract
- The relation among sea surface temperature (SST) cooling in the southeastern Indian Ocean (SEIO), oceanic Rossby waves, and the seasonal onset of the Madden–Julian Oscillation (MJO) is examined for the period 1993–2012.
- Positive SST anomalies migrate concurrently with the downwelling Rossby waves but are followed by a wide-spread cold SST area in the SEIO from boreal summer to fall (Fig. 1). Whereas the SEIO cooling tends to persist for a longer period until November during positive Indian Ocean Dipole (IOD) and/or El Niño years, it occurs irrespective of the IOD.
- Convection related to the MJO events during boreal winter propagates from the Indian Ocean to the Pacific only after the SEIO cooling is terminated (Fig. 2). The SEIO cooling tends to prevent intraseasonal convection from propagating eastward to the Pacific via excitation of the local circulations over the eastern Indian Ocean and the tropical western Pacific.
Jensen et al. (2015)
Jensen, T. G., T. Shinoda, S. Chen, and M. Flatau, 2015 : Ocean response to CINDY/DYNAMO MJOs in air-sea coupled COAMPS. J. Meteor. Soc. Japan, 93A, 157-178.
https://doi.org/10.2151/jmsj.2015-049 Graphical Abstract
- When an intense MJO event started on Nov 22, 2011, a rapidly intensifying Yoshida jet was generated in the central equatorial Indian Ocean with zonal currents exceeding 1 m/s in the mixed layer. The jet was observed by RAMA buoys and modeled in COAMPS (Fig. 1). By the end of Dec 2011, the jet spanned the width of the Indian Ocean (Fig. 1, bottom). The MJO generated jet is different from the seasonal Wyrtki Jet which has its maximum velocity in the thermocline at about 100 m.
- The sea surface height (SSH) response to each MJO event is an eastward propagating equatorial Kelvin wave (positive SSH anomaly, Fig. 2 center) and off-equatorial negative anomalies propagating westward as Rossby waves (Fig. 2, left and right). Upon reaching the Indonesian coast, a fraction of the Kelvin wave reflects and propagate westward as equatorial Rossby waves with positive anomalies off the equator (Fig. 2, left and right).
- During the inactive phase of the MJO, wind speeds are low and a large diurnal cycle with an amplitude of about 1.5°C is seen in the COAMPS simulations as well as the observations. During the active phase, the diurnal cycle is absent. COAMPS is able to simulate the diurnal warming during the inactive MJO due to its 0.5 m resolution of the upper 10 m of the ocean.