MISMO Workshop

- Abstract -

Yokohama Institute for Earth Sciences / JAMSTEC, Yokohama, JAPAN

November 25 - 26, 2008

Oral Session

Brief Review on MISMO

Kunio YONEYAMA (IORGC/JAMSTEC)

The field experiment MISMO (Mirai Indian Ocean cruise for the Study of the MJO-convection Onset) took place in the central - eastern equatorial Indian Ocean during October - December 2006. The aim of MISMO was to capture the atmospheric and oceanic features of the equatorial Indian Ocean when convection in the Madden-Julian Oscillation (MJO) was initiated. We constructed the atmospheric sounding array with the Mirai at 0, 80.5E and Maldives Islands (Gan at 0.7S, 73.2E and Hulhule at 4.2N, 73.5E), while oceanic observational array was constructed with m-TRITON and ATLAS buoys and sub-surface ADCP moorings around the Mirai.

While the intensive observations were carried out under the relatively strong positive Indian Ocean Dipole (IOD) event, large-scale cloud system developed over the observation area in mid-November, and then they moved eastward from late November. From the analysis of wavenumber-frequency filtered outgoing long-wave radiation data, it was confirmed that this eastward propagation was associated with the MJO, although they dissipated before arriving at Indonesian maritime continent. Therefore, we could obtain invaluable data for the study of the MJO-convection onset as well as oceanic variation in the positive IOD event. These data have been released from the MISMO web site at http://www.jamstec.go.jp/iorgc/mismo/ since January 2008. In this talk, a summary on observation and general atmospheric and oceanic conditions will be presented.

3 Kelvin-Type disturbances observed from September to December in 2006

Kazuaki YASUNAGA (IORGC/JAMSTEC)

The large scale convergence associated with the Kelvin-type disturbance propagated into the Indian Ocean 3 times from October to December 2006, and promoted the development of cloud cluster there. The eastward-propagating convergence was becoming obscure from October to December. On the other hand, the later developed cloud cluster was better organized, and the last one was diagnosed as MJO. The westward-propagating Rossby wave was observed in the all cases, and the cloud cluster developed at the intersection of Kelvin-type disturbance and Rossby wave. Sea surface temperature over the western and eastern Indian Ocean was critical to the development of MJO.

Small-scale structure of eastward-propagating precipitation systems within a supercloud cluster during the MISMO IOP

Hiroyuki YAMADA¹, Ryuichi SHIROOKA¹, Masaki KATSUMATA¹, and Kunio YONEYAMA¹ (1:IORGC/JAMSTEC)

The small-scale structure of a supercloud cluster (hereafter, SCC), observed during the later period of the MISMO field experiment, was examined using data of Doppler radars, upper-air soundings, and satellite microwave sensors. This SCC was characterized by the eastward propagation of shallow convective rainbands (ER) while the westward propagation of upper-level cloud shield (WS) was dominant in the infrared images. The purpose of this study was to clarify the horizontal and vertical structure of ERs for understanding the mechanisms governing the different propagation in the lower and upper levels within the SCC. Analyses were performed using composite data on the orthogonal coordinates (X’-Y-Z) in which the zonal axis is relative to the longitude of the center of each ER. The same analyses were also conducted for WSs to clarify the differences from ERs.

Results show that the ERs have the horizontal extension of rainfall area ~500 km in zonal direction and ~1000 km in meridional one. Shallow convective echoes are predominant in the forward portion (eastern side) where the convergence of zonal wind component in the lower troposphere and the divergence near 300-hPa level are significant. This evidence indicates that the ERs have the vertical structure similar to a Kelvin wave with shallow depth (~ 8 km). In contrast, the WSs mainly consist of stratiform echoes, and a link with vertical motion was not significant. The results also show that convection is deepened where both an ER and a WS are intersected each other.

These results lead to the conclusion that the SCC in the MISMO period consisted of shallow mesoscale disturbances propagating eastward, which were hardly identified from IR and OLR data because they were masked by westward-propagating upper-level cloud shields.

Convective developments in the Madden-Julian Oscillation with equatorial Rossby wave in the equatorial Indian Ocean

Chiharu TAKAHASHI (IORGC/JAMSTEC)

An observational study of differences in the convective onset and development of the Madden- Julian oscillation (MJO) in association with the westward propagation of an equatorial Rossby wave (ER) is conducted by the composite analysis using 22yr data of the NOAA outgoing longwave radiation, sea surface temperature (SST), and JRA/JCDAS reanalysis over the equatorial Indian Ocean (IO).

About 45% cases of the MJO initiated with the coming of ER event over IO. The anomalies of the low-level moisture and high SST precede the eastward propagating active convective anomalies in all events. The ER event shows convective developments in smaller positive moisture anomaly and colder SST anomaly than those of no ER event. The MJO convection with ER event also can develop in smaller low-level convergence than no ER event over the west IO (west of 70E). After that, high moisture and convergence anomalies more rapidly increased from the low to middle atmosphere over the middle IO (70-90E) by the coming ER event than those of no ER event. The ER event show that the enhancement of the friction-induced meridional convergence over the east IO (east of 90E) 10 days and then zonal convergence 5 days ahead of convection peak, respectively. These increases result in the larger moisture convergence at the low-level than no ER event. On the other hand, the zonal moisture convergence largely contributes to the total low-level convergence in the no ER event, which is thought of the formation by Kelvin wave.

In ER event, suppressed convective anomalies with the low-level anticyclonic circulations appear north and south of the equator during convective developing phase. These suppressed convective regions are accompanied by the cold temperature anomaly in the mid-troposphere. Result indicates that the westward propagating anticyclonic circulations with ER produce the condition of convective instability and intensify the low-level convergence over the high SST of IO, resulting in fast-development of convection. It is considered that most of ER events correspond to the previously presented "primary" MJO events.

Observed atmospheric heating profile and its relationship to the process toward the convectively active phase

Masaki KATSUMATA (IORGC/JAMSTEC)

The budget analysis was carried out using the three sounding points deployed in MISMO IOP for 26 days period toward the convectively active phase. In the period, the moist layer grew vertically and stepwise when the eastward-propagating cloud signals (EPCSs) passed over the sounding array.

The EPCSs have similar structure to the moist Kelvin wave, but with the slow propagation speed (8 m/s). The temporal change of Q1 and Q2 shows relatively bottom-heavy heating / drying profile when the EPCS passed over the sounding array. The shallow precipitating clouds are also evident from the radar data. These suggest that the shallow heating within the EPCSs could promote the slow propagation of the EPCSs. The favorable condition for the convection (high CAPE and low CIN) was built-up before EPCS arrived. Some possible reasons to make these conditions (frictional convergence, clear condition with northerly phase of mixed Rossby-gravity wave, rising SST with large diurnal cycle, etc.) are observed.

The validity of the budget analyses was also examined, by comparing with the various rainfall data. The temporal variations agree, at least before the convectively active phase after November 16. The simulation of the budget analysis using theoretical MJO circulation indicate that the Rossby-wave component cause the error for the budget analysis with MISMO sounding array. The additional fourth point could reduce the error.

Air-sea energy fluxes with on-board eddy-covariance system during MISMO

Osamu TSUKAMOTO¹, Yoshihito SUWA¹, Fumiyoshi KONDO¹, Kunio YONEYAMA² (1: Okayama University, 2:IORGC/JAMSTEC)

During the MISMO cruise, present authors experienced the on-board eddy-covariance measurement of surface energy fluxes on R/V MIRAI, JAMSTEC. A month long stationary observation continued at the equator, 80E using R/V MIRAI in Nov 2006. During a month, 3-hourly flux runs were carried out steaming up against the wind to minimize the flow distortion and thermal effects of the ship body on the flux system installed at the top of the foremast.

Surface radiation fluxes are available with the SOAR system on R/V MIRAI and downwelling shortwave and longwave radiations. Upward radiations were calculated with the albedo(0.055) and blackbody radiation with sea surface temperature. Surafce net radiation were synthesized with the eddy fluxes of sensible and latent heat and lead to net sea surface flux as ocean warming. The latent heat flux can also lead to surface water vapor supply to the atmosphere.

The COARE bulk flux algorithm were applied based on the meteorological/ oceanographic parameters from SOAR system and compared with the eddy-covariance results. Finally, surface heat budget analysis is applied with these flux datasets to estimate ocean warming.

Equatorial upwelling in the central Indian Ocean estimated from moored ADCP array during the MISMO

Takanori HORII¹, Yukio MASUMOTO^{1, 2}, Iwao UEKI¹, Hideaki HASE¹, and Keisuke MIZUNO¹ (1: IORGC/JAMSTEC, 2: Graduate School of Science, University of Tokyo)

As a part of the field experiment MISMO, ocean intensive observations, using an array of surface and subsurface moored buoys, were conducted around 80.5°E in the equatorial Indian Ocean during October--November 2006. This presentation reviews ocean condition during the MISMO, with an emphasis on the equatorial upwelling estimated by the ocean current data.

The moored buoy data shows relatively shallow thermocline, which intensifies with time during the one-month period, and surface low-salinity water over the high-salinity water in the thermocline depth during the MISMO observation period. Data from four acoustic Doppler current profilers (ADCP) shows eastward subsurface zonal flow under westward flowing surface current, suggesting unusually strong vertical shear above the thermocline. Intraseasonal meridional current variability having a period of 15--20 days is also observed. These unique conditions relative to climatology were associated with a peak phase of the positive Indian Ocean Dipole.

Using an array of the ADCPs, vertical velocity (w) is estimated by the continuity equation. Results indicate strong upwelling event below 90 m with a maximum velocity larger than 10m/day, which lasted about a week in the middle of the MISMO period. The upwelling was produced by the horizontal divergence, in which both zonal and meridional current showed divergent component. The variations of zonal current were consistent with local wind, while the meridional currents and local winds were uncorrelated, suggesting an effect of remotely forced equatorial wave. Possible influences of the upwelling on the ocean temperature variation will be also presented.

Physical and biogeochemical coupling in the equatorial Indian Ocean over short time scale from MISMO time-series

S. Prasanna KUMAR¹, P. BYJU¹, Divya DAVID¹, Kunio YONEYAMA², Akio ISHIDA²,Takanori HORII², and Keisuke MIZUNO²(1: National Institute of Oceanography, India, 2: IORGC/JAMSTEC)

Equatorial oceans are special regions of World Ocean which has direct coupling to the atmosphere and are important in regulating the earth’s climate. However, our understanding of the bio-physical coupling in the equatorial Indian Ocean (EIO) is almost non-existent due to non-availability of co-located physical and biogeochemical measurements. In 2006 when Indian Ocean Dipole (IOD) was active, R.V. Mirai occupied a time-series position at equator and 80.5oE during 27 October to 21 November and collected a high-resolution time-series data on physical, chemical and biological parameters. The thermohaline structure showed high frequency oscillations with a deepening of upper isothermal layer shoaling of lower thermocline. Towards the end of the time-series the upper ocean warmed by 1oC followed by a cooling of SST and subsequent development of inversion layer. The warming was driven by advection of warm waters into the time-series location combined with a net heat gain by the ocean while cooling was due to advection of colder SST and increased evaporation. The deepening of subsurface chlorophyll maxima (SCM) and the enhancement of chlorophyll within the SCM was tightly coupled to the physical processes. We attribute this to the deepening of nitracline associated with the anticyclonic wind-stress curl and the reduction in the attenuation coefficient (kd490).

Vertically fine structure of the stationary circulation in the upper troposphere over the Indian Ocean

NISHI Noriyuki¹, NISHIMOTO Eriko², SIOTANI Masato², HAYASHI Hiroo³, TAKASHIMA Hisahiro⁴, and TSUDA Toshitaka² (1: Graduate School of Science/Kyoto University, 2: Research Institute for Sustainable Humanosphere/Kyoto University, 3: Japan Aerospace Exploration Agency, 4: FRCGC)

Vertical fine structure of the tropical circulation in the upper troposphere was analyzed with using the dry temperature data obtained by COSMIC radio occultation. The data have very high vertical resolution and global coverage. Two-year record observed by COSMIC (July 2006 - August 2007) was utilized to detect stable layers (with large dT/dz value) in the upper troposphere. Quasi stationary stable layers with relatively small vertical extent are detected, separated from the deep stratospheric stable layer, in the western Indian Ocean in the boreal summer. The stable layer has tilted structure with height; the most stable region shifts eastward and northward with height.

We also made statistical analysis with objective reanalysis data made by ECMWF (ERA-40, 1979-2001). Negative height anomaly at 150 hPa, which is associated with the stably layer, is located at the western edge of the strong easterly jet. The magnitude/position of low height anomaly in each year has high correlation with that of the easterly jet around 20N. We discussed possible mechanisms to produce these vertical fine structures from the viewpoints of monsoon circulation and stationary equatorial trapped waves.

Ship-based aerosol optical properties measurements over the Ocean

Kazuma AOKI (University of Toyama)

Aerosol optical properties are studied using data from ship-borne sky radiometer measurements. We started the monitoring of aerosols by using a sky radiometer since 1994. We are seeking in this data information on the aerosol optical characteristics (ex. aerosol optical thickness, single scattering albedo, and size distribution of volume) over the ocean. The Sky radiometer is a portable instrument that takes measurements of aerosols only during daytime under clear sky condition. The sky radiometer (PREDE Co., Ltd., Tokyo, Japan) has a two type. One is the most popular used version of ground-based sky radiometer (POM-01 and POM-02). The other one is the ship-borne sky radiometer (POM-01 MKII). POM-01 and 01 MK-II is the most basic instruments, have a seven wavelength (0.315, 0.4, 0.5, 0.67 or 0.675, 0.87, 0.94, and 1.02 μm). POM-02 is the extend instrument, have an eleven wavelength (POM-01 + 0.34, 0.38, 1.6, and 2.2 μm). It observes both direct solar irradiance and diffuse sky radiation at every 5 minutes (ground measurements is 10 or 15 minutes). We present the temporal and spatial variation of the aerosol optical properties in each cruse (ex. R/V Mirai) using sky radiometer. The aerosol optical properties have a clearly spatial variability. Especially, it is high at Indian Ocean region.

Results on daily simulation using a cloud resolving model over the tropical Indian Ocean during the MISMO

Taro SHINODA¹, Mitsuharu NOMURA¹, Masaya KATO¹, Masahiro WATANABE², and Kazuhisa TSUBOKI1¹ (1: Hydrospheric Atmospheric Research Center/Nagoya University, 2: Center for Climate System Research/The University of Tokyo)

To confirm the predictability using a cloud-resolving model over the tropical ocean, we examined daily simulations using the Cloud Resolving Storm Simulator (CReSS) over the tropical Indian Ocean during the MISMO in 2006. Data of the Global Spectral Model (GSM: Horizontal grid resolution was 1.25 degree) provided by Japan Meteorological Agency (JMA) were used as the initial and boundary conditions of the MM5 simulations whose horizontal grid resolution was 20 km. The MM5 simulations were carried out for 36 hours from 12 UTC every day and the results were utilized as the initial and boundary conditions of the CReSS simulations whose horizontal grid resolution was 5 km. The 5-km CReSS simulations were conducted for 27 hours from 9 hours after the start of the MM5 simulations. In the 5-km CReSS simulation, we applied the 1.5 Turbulent Kinetic Energy (TKE) scheme and the double-moment cold rain parameterization.

In these daily simulations, two problems arose. One was the development of the stratiform clouds atop of the boundary layer by the lack of the transport process of water vapor from the boundary layer to free atmosphere by cumulus clouds. We have to need to apply the shallow cumulus parameterization for the 5-km simulations. The other was the lack of reproducing the structure of precipitation systems. The precipitation areas appeared as the cell and were not separated convective and stratiform regions. This showed that finer horizontal grid resolution should be needed for reproducing precipitation systems.

Using the 1-km horizontal grid resolution, we can solve these problems. In the presentation, we also show some statistical parameters to verify the large-scale condensation scheme in the GCM from the CReSS simulations.

The impact of the assimilation of additional sondes during MISMO in ALERA

Qoosaku MOTEKI (IORGC/JAMSTEC)

The impact of the assimilation of the additional sondes during MISMO in an objective analysis was investigated. The objective analysis is called "ALERA" using the assimilation technique with the ensemble Kalman filter. ALERA provides analysis values (ensemble mean) and their error values (ensemble spread) at each grid point. Using the error information, a test of significance is possible to be performed for the impact signal of the assimilation and we can discuss the true assimilation impact without the errors depending on the model. The strong impact of the assimilation of the MISMO data appeared over the Indian Ocean at the MJO onset. In addition, the impact signal propagated eastward and typhoons over the tropical western Pacific was found to be affected by the MISMO data. This result shows that the MISMO data have a great impact on the predictability of the generation of typhoons.

Global cloud-resolving simulations of MJO events in November 2006 - January 2007
~ A brief Introduction ~

Hiroaki MIURA (Colorado State University/FRCGC)

A global cloud-resolving model named Nonhydrostatic Icosahedral Atmosphere Model (NICAM) was used to simulate Madden-Julian Oscillation (MJO) events started in mid-November and mid-December 2006. The slow eastward movement of the organized cloud systems in the MJO was reproduced in the December case. The onset of the MJO convection observed in MISMO was simulated in the November case. A sensitivity test suggested that relatively colder sea surface temperature in the western Indian Ocean seemed to play an important role in maintaining the strong convection, resulting in the onset of the MJO.

Global cloud-resolving simulations of MJO events in November 2006 - January 2007
~ multi-scale structure ~

Tomoe NASUNO (FRCGC/JAMSTEC)

Global cloud-resolving simulations are useful to investigate wide range of mechanisms in the MJO events; spatially mesoscale to global scale and temporally diurnal variation to the MJO cycles (Satoh, session-5 in this workshop). Simulations of the MJO events that occurred in November 2006-January 2007 have been conducted using a global cloud resolving model, NICAM (Miura, session 4). Quantitative evaluations of the simulations in cloud statistics, diurnal cycle of precipitation, formation of tropical cyclones, and EOF analysis have been conducted. They assessed good reproducibility of the simulations in the primary aspects of the MJO, and also revealed several deficiencies of the current model. Clarification of the multiple interactions among the various convective disturbances embedded in the active phase of the MJO events is a key to understand the behavior of the whole system. With this perspective, multiscale organization of convection was examined for the MJO event that started in mid December 2006. The simulations reproduced the observed hierarchical convective structure including planetary-scale convective envelope, eastward-propagating (10--15 m s-1) disturbances (EPDs) with zonal scales of 1000--2000 km and westward-propagating cloud clusters (CCs) of O(100 km). It was found that squall-type clusters can easily develop when the circulation associated with the MJO intensified. Relevance of synoptic-scale wave disturbances to the organization of convection in the EPDs was also suggested.

Eastward propagation mechanism and asymmetric horizontal structure of super cloud clusters in the equatorial region -- an instability view of positive - only wave CISK --

Masanori YOSHIZAKI (IORGC/JAMSTEC)

Super cloud clusters (SCCs) embedded in the MJO are large - scale cloud systems with a horizontal scale of O (1000 km), propagating eastward in tropics (Nakazawa, 1988; Nasuno et al., 2007). This propagation of the SSCs might determine that of MJO. In order to understand the propagation mechanism and asymmetric horizontal structure of SCCs as simple as possible, linear and nonlinear models are developed on the equatorial beta plane with positive - only wave CISK and large horizontal viscosity / diffusivity, using nonhydrostatic icosahedral atmospheric model (NICAM) outputs which exhibit good performances of eastward propagation of SCCs in an aquaplanet simulation.

First, a linear model is applied by using a vertical - mode expansion in the idealistic troposphere. The propagation property of growing disturbances is classified into two groups; (i) a single slowly westward - propagating disturbance and (ii) a pair of oppositely - propagating ones. From (ii)-type disturbances, asymmetric structures in an east - west direction become large with time due to the equatorial beta effect, resulting in the selection of eastward propagating disturbance.

Second, the nonlinearity relaxes threshold values for propagation property compared with the linear model. A finite - amplitude eastward propagating disturbance is simulated with quasi - uniform propagation speed. Its horizontal structure shows an asymmetric horizontal structure similar to Gill (1980) response pattern; the Kelvin wave pattern on the eastern side of heating and the Rossby wave pattern on the western side.

The comparison of positive - only and ordinary wave CISK cases shows similar results for the propagation property, indicating that neutral equatorial waves do not play any role for the propagation mechanism of SCCs.

The MJO, equatorial waves, and TCs over the South Indian Ocean: Their associations and use for prediction

Matthew WHEELER¹, Miloud BESSAFI², and Anne LEROY³(1: Centre for Australian Weather and Climate Research, 2: Universite de La Reunion, 3: Meteo France, Noumea)

MISMO was partly motivated by the importance of the Madden-Julian oscillation (MJO) and other tropical intraseasonal variability for modulating tropical cyclones (TCs), and during MISMO an influence on regional convection was seen from both an MJO event and a convectively-coupled equatorial Rossby wave (Yoneyama et al. 2008; Bull. Amer. Met. Soc.). In this talk I will summarize the observed long-term relationships of the MJO and convectively-coupled equatorial waves (CCEWs) with TCs over the South Indian Ocean as described by Bessafi and Wheeler (2006; Mon. Wea. Rev.), and attempts to use these relationships for operational intraseasonal prediction described by Leroy and Wheeler (2008; Mon. Wea. Rev.). Both the MJO and Rossby waves have a strong relationship with TC genesis over the South Indian Ocean, and the relationship with the MJO has proven to be quite useful for real-time predictions out to at least week 3. Such predictions are available for the hole of the southern hemisphere from http://www.meteo.nc/espro/previcycl/cyclA.php. New work is also being conducted on the mechanism of the modulation (with S. Camargo and A. Sobel).

Use of a global cloud-resolving model NICAM for MJO studies

Masaki SATOH (JAMSTEC/Univ. of Tokyo)

Global cloud-resolving simulations with NICAM show realistic behaviors of MJO, including multi-scale cloud structure, propagation, and the onset, as presented by T. Nasuno and H. Miura in this workshop. Simulations with NICAM now extends to several months and show periodicity of MJOs and the intra-seasonal variability. NICAM reproduces many aspects of cloud-precipitation systems in the tropics, and reveals mechanisms behind them. This talk introduce the progress of NICAM and MJO studies and how NICAM can be used to collaborate with the future field experiments of MJO.

Variability of the oceanic upper layers associated with the MJO

Naoki SATO (IORGC/JAMSTEC)

We used satellite and in-situ observation data to examine the intraseasonal variability of the oceanic surface and subsurface layers associated with the Madden-Julian oscillation (MJO). The sea-surface temperature (SST) was higher (lower) to the east (west) of a convection maximum of the MJO in the tropical Indian Ocean, the maritime continent, and the western Pacific in southern summer. The SST difference (maximum minus minimum) was large (1.5 deg.) where the mean sea-surface wind was westerly. Examination of sea-surface wind data revealed that the anomalous easterly wind prevailed to the east of the large-scale convection center, resulting in a negative anomaly of scalar wind speed. By analyzing Argo data, we demonstrated that vertical mixing was suppressed due to weak surface wind when SST increases. Conversely, the SST decreases to the west of the MJO, in association with higher wind speed and enhanced vertical mixing. These results suggested that vertical mixing plays an important role in the SST variability associated with the MJO. They also implied that the westerly wind in the basic field is essential to the air-sea coupling through the changes in the scalar wind speed.

The proposed field experiment CINDY2011: Basic Strategy

Kunio YONEYAMA (IORGC/JAMSTEC)

In order to investigate the initiation process of the MJO-convection and relevant atmospheric and oceanic variability in the Indian Ocean, the field experiment CINDY2011 (Cooperative Indian Ocean experiment on isv in the Year 2011) has been proposed. Its main target area is the "equatorial" Indian Ocean and we are planning to conduct the intensive observation in late 2011 (October - December). While MISMO captured the onset of a weak MJO-convection and its analyses indicated that recharge-discharge process might play a key role for the development of the intraseasonal convection, it also suggested that equatorial Kelvin and Rossby waves played a crucial role for the timing of the development of large-scale convection. It is, however, difficult to deduce the relationship to such large-scale phenomena from MISMO’s limited coverage data. In addition, one month observation period did not observe the entire life cycle of the intraseasonal variability. Furthermore, MISMO did not capture the features of the western side of convective center nor clear oceanic responses to the MJO. Thus, further field experiment is strongly desired to answer to them and it leads to plan CINDY.

Basic strategies of CINDY can be summarized as follows.

First, we will try to construct a long-time and wider areal observation network with ships and land-based sites as well as RAMA buoy array and satellites. Thus, while we will try to get enough ship-time and deploy land-based sites, collaboration with other field projects are also discussed.

Second is the tight relationship with numerical research. Currently, we are discussing the collaborative work with numerical research groups who developed the global cloud (cluster)-resolving model "NICAM" . Input from It is requested that such numerical research groups will be involved in the campaign from the initial stage of planning.

Finally, we will have the open data policy. Therefore, at present, it is planned that quality controlled data would be opened from the web site of CINDY within one year from the end of campaign.

Repeat Hydrography/Carbon observations in the Indian Ocean by JAMSTEC

Akihiko MURATA and others (IORGC/JAMSTEC)

The ocean regulates regional and global climate by exchanging heat and materials with the atmosphere, and by circulating them in the interior of the ocean. Thus it is an urgent task to estimate accurately how much heat and anthropogenic CO₂ are absorbed in the ocean. This is because these properties are crucial in determining the magnitude of global warming in future. For the accurate estimation, high-accurate data have to be collected repeatedly at an interval of a decade at least. Now we have a plan to conduct hydrographic observation along observation lines in the Indian Ocean, where high-accurate data were obtained in 1994-1996 by a World Ocean Circulation Experiment (WOCE) Hydrographic Programme (WHP) cruise. We will conduct the re-occupation observation under the framework of Climate Variability and Predictability (CLIVAR)/CO₂ program.

We have repeated the re-occupation observations in the world oceans over the past 7 years. From the obtained data, we detected decadal changes of heat storage and increases of anthropogenic CO₂, which are closely related to water masses characteristic in individual oceans. We conduct the observation to examine these decadal changes in relation to water masses in the Indian Ocean.

Developing a plan for Australian participation in CINDY-2011

Matthew WHEELER¹, Eric SCHULZ¹, Harry HENDON¹, and Gary MEYERS² ( 1: Centre for Australian Weather and Climate Research, 2: Integrated Marin Observing System/University of Tasmania )

Intraseasonal variability (ISV) of tropical convection, and in particular that associated with the Madden-Julian oscillation (MJO), provides an important link between weather and climate. Recognising the importance of the MJO for the climate system and the primary role of the Indian Ocean as a source region for tropical ISV, scientists from several countries have recently begun planning a field experiment in the equatorial Indian Ocean -- the Cooperative Indian Ocean Experiment on ISV in the Year 2011 (CINDY-2011). The expected outcomes of this experiment are improved understanding, simulation and prediction of the MJO and its interaction with the ocean and global climate. This presentation will describe the interest from Australian scientists in participating in CINDY-2011 in the form of a research ship and cruise to the equatorial Indian Ocean. The capability of the Australian research ship for conducting atmospheric and oceanographic observations will be described, as will its participation in previous similar field campaigns (e.g. JASMINE and TWP-ICE). How an Australian ship and scientists may best be able to participate in conjunction with those from other countries requires further discussion.

Scientific objectives of TRIO and SWICE experiments

Jean-Philippe DUVEL (Laboratoire de Météorologie Dynamique/ENS)

The TRIO (Thermocline Ridge of the Indian Ocean) project and cruise is in continuity of the Vasco-Cirene project. It will explore air-sea interactions at synoptic (cyclones and tropical storms), intraseasonal (Madden-Julian Oscillation) and interannual timescales in the 5°S-15°S band of the Indian Ocean. In 2009-2010, TRIO will focus on modelling studies and analysis of existing data. The TRIO cruise, in early 2011, will contribute to the development of the RAMA array (Indian Ocean counterpart of TAO and PIRATA) and interact with several satellite programs (Megha-Tropiques, SMOS, Altika). TRIO will also have strong interactions with the synchronous SWICE (South West Indian Ocean Cyclone Experiment) project.

The 5°S-10°S band in the Indian Ocean is a region where several phenomena of significant climatic influence build up. It is a cyclogenesis region for tropical cyclones striking inhabited islands of the Indian Ocean and the African coast. It was recently shown that it is one of the regions of the globe where atmospheric intraseasonal variability (e.g. Madden Julian Oscillation, MJO) is associated with the strongest oceanic response. Finally, there is an important interannual variability over this region (e.g. Indian Ocean Dipole, IOD), which has significant implications on the rainfall over India during the following monsoon. There are interactions between these phenomena at different time scales. For example, the IOD modulates the heat content in the southwestern tropical Indian Ocean and influences the cyclone distribution near La Réunion and Madagascar. Phenomena developing over this region have some impacts over remote regions, in particular the Pacific Ocean. The strong prevalence of ocean atmosphere interactions at a variety of timescales in this region is due to average wind structure that lifts the thermocline. The elevated thermocline leads to different oceanic processes increasing the SST response to atmospheric perturbations. In addition, while upwellings are generally associated with lower sea surface temperature, the ocean surface remains warm here, enabling the development of deep atmospheric convection. This gives strong air-sea interaction associated with the convective perturbations at different time scales.

The TRIO project aims at analysing the coupled processes associated with these phenomena (i.e. cyclones, MJO, IOD), their scale interactions and their predictability. TRIO is an integrated project that continues and expands the Vasco-Cirene programme. TRIO will combine modelling, analysis of past observations and a new field experiment. The field experiment is mostly based on a cruise in the 5°S-10°S band and will be coordinated with SWICE (South West Indian Ocean cyclone experiment), with three satellite programs (Altika, SMOS and Megha-tropiques) and with the development of a mooring array in the Indian Ocean (the RAMA array). The TRIO cruise and SWICE are scheduled for late 2010 / early 2011. This takes opportunity of the Atalante presence in the western Pacific in late 2010 and of two other cruises planned in the Indonesian region in late 2010. The TRIO cruise will cover the 5°S-10°S band in the Indian Ocean and the northwestern Australian basin. These two regions have recently been identified as the two regions with the strongest surface temperature signals associated with the MJO.

HARIMAU radar-profiler network over the maritime continent : Collaborations with MISMO until now and CINDY in future

Manabu D. YAMANAKA¹ and Shuichi MORI¹ (1: IORGC/JAMSTEC)

The Hydrometeorological ARray for Isv-Monsoon AUtomonitoring (HARIMAU), a 5-year project under the Japan EOS Promotion Program (JEPP) contributing to the Global Earth Observation System of Systems (GEOSS), has begun in 2005 to set up a radar-profiler network for observing the world's most active convective activities over the Indonesian Maritime Continent (IMC). Rainfall and wind distributions are displayed in nearly real time on the internet. Both scientific understanding and practical concepts on intraseasonal variations (ISVs) interacting with larger (seasonal and interannual) and smaller (diurnal or local) scale phenomena will be established.

Two times of intensive observations using mainly two XDRs (one installed by HARIMAU and the other transported from Hokkaido University) at the western coast of Sumatera Island were carried out during MISMO period in October-December 2006 and also in April-May 2007. Fast migration from land to sea of nocturnal convective systems and their re-development associated with local hazardous windstorm were frequently observed, which would clearly demonstrate both scientific capability and social usefulness of the HARIMAU network.

In September 2008 the whole network with five stations have been completed. In addition the Indonesian government has also constructed seven radar stations. In the CINDY period all of the radars/profilers will be operated, and they will provide vivid evidence on modification of the ISVs over the IMC on the way of their eastward propagation from the Indian Ocean to the Pacific.