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Kunio Yoneyama, Chidong Zhang, and Charles N. Long

An international field campaign aiming at atmospheric and oceanic processes associated with the Madden–Julian oscillation (MJO) was conducted in and around the tropical Indian Ocean during October 2011–March 2012. The objective of the field campaign was to collect observations urgently needed to expedite the progress of understanding the key processes of the MJO, focusing on its convective initiation but also including propagation and maturation, and ultimately to improve skills of numerical simulation and prediction of the MJO. Primary targets of the field campaign included interaction of atmospheric deep convection with its environmental moisture, evolution of cloud populations, and air– sea interaction. Several MJO events were captured by ground-based, airborne, and oceanic instruments with advanced observing technology. Numerical simulations and real-time forecasts were integrated components of the field campaign in its design and operation. Observations collected during the campaign provide unprecedented opportunities to reveal detailed processes of the MJO and to assist evaluation, improvement, and development of weather and climate models. The data policy of the campaign encourages the broad research community to use the field observations to advance the MJO study.

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Kunio Yoneyama, Yukio Masumoto, Yoshifumi Kuroda, Masaki Katsumata, Keisuke Mizuno, Yukari N. Takayabu, Masanori Yoshizaki, Ali Shareef, Yasushi Fujiyoshi, Michael J. McPhaden, V. S. N. Murty, Ryuichi Shirooka, Kazuaki Yasunaga, Hiroyuki Yamada, Naoki Sato, Tomoki Ushiyama, Qoosaku Moteki, Ayako Seiki, Mikiko Fujita, Kentaro Ando, Hideaki Hase, Iwao Ueki, Takanori Horii, Chie Yokoyama, and Tomoki Miyakawa

The Mirai Indian Ocean cruise for the Study of the Madden-Julian oscillation (MJO)-convection Onset (MISMO) was a field experiment that took place in the central equatorial Indian Ocean during October–December 2006, using the research vessel Mirai, a moored buoy array, and landbased sites at the Maldive Islands. The aim of MISMO was to capture atmospheric and oceanic features in the equatorial Indian Ocean when convection in the MJO was initiated. This article describes details of the experiment as well as some selected early results.

Intensive observations using Doppler radar, radiosonde, surface meteorological measurements, and other instruments were conducted at 0°, 80.5°E, after deploying an array of surface and subsurface moorings around this site. The Mirai stayed within this buoy array area from 24 October through 25 November. After a period of stationary observations, underway meteorological measurements were continued from the Maldives to the eastern Indian Ocean in early December.

All observations were collected during an El Nino and a positive Indian Ocean Dipole (IOD) event, which tended to suppress convection in the western Pacific and eastern Indian Ocean in throughout much of November 2006. However, as the IOD began to wane in mid-November, an abrupt change from westerly to easterly took place in upper tropospheric winds in the MISMO study region. By late November and early December, deep convection developed over the central Indian Ocean and eastward movement of large-scale cloud systems were observed. This article describes these variations in detail and how they advance our understanding of the onset of tropical deep convection on intraseasonal time scales.

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