Doppler Radar Observation of the Structure and Characteristics of Tropical Clouds during the TOGA-COARE IOP in Manus, Papua New Guinea

Multi-scale convective organization in a Madden-Julian Oscillation (MJO) event that occurred during December 2006 and January 2007 was studied by global numerical experiments using explicit moist physics. The simulations successfully reproduced the eastward-propagating (@5 m s À1 ) convective envelope of the MJO with a zonal scale of 5000-10,000 km, which included eastward-propagating (10-15 m s À1 ) disturbances (EPDs) and westward-propagating cloud clusters (CCs) with zonal scales of 1000-2000 km and O (100 km), respectively.The simulated EPDs were composed of CCs, with new clusters growing to the east of older ones. When the large-scale circulation associated with the MJO intensified, the EPDs formed well-organized squall-type clusters (rainbands). The dynamical structure of the simulated EPDs was reminiscent of moist Kelvin waves. Relevance of westward-propagating wave disturbances including cross-equatorial flow to convective organization in the EPDs was also suggested.

Section: Summary and Discussionsupporting

confidence: 78%

Multi-scale Organization of Convection in a Global Numerical Simulation of the December 2006 MJO Event Using Explicit Moist Processes

Nasuno

Miura

Satoh

et al. 2009

“…Rainfalls at Bowat were prominent in the early afternoon when it was fair in the morning. An example of an isolated cloud over Manus Island is shown by Takahashi and Uyeda (1995). In order to compare the different features of the analyzed radar echoes with each other and to characterize the radar echoes during the observation period, the relation between the duration time to reach to the maximum echo area (> 19 dBZ) from the first echo (>19dBZ) and the maximum echo area is plotted in Fig.…”

Section: Resultsmentioning

confidence: 99%

Doppler Radar Observations on the Structure and Characteristics of Tropical Clouds during the TOGA-COARE IOP in Manus, Papua New Guinea

Uyeda

Asuma

Takahashi

et al. 1995

Self Cite

Observations of tropical convection and cloud clusters with two X-band Doppler radars were carried out on Manus Island, Papua New Guinea for two and a half months from 12 November 1992 during the Intensive Observation Period (TOP) of the TOGA-COARE. Several different types of clouds were observed by Doppler radars during the period, such as squall lines, convective clouds and stratiform clouds associated with cloud clusters, isolated convective clouds over the island in the day time, etc. Outlines of the observations on Manus Island and brief reviews of the results of these observations are described. Preliminary summaries of the analyses on the observations are: 1) A warm rain process dominates at the beginning stage of radar echo development and the maximum radar reflectivity is recognized at this stage, 2) The maximum echo top height is observed within 3 hours from the first echo, 3) The maximum echo area within the radar range was analyzed a few to several hours later than the time of maximum echo top height corresponding to the size of cloud cluster, 4) In the long-lasting stratiform echo, updrafts independent from those below the melting layer were identified above the melting layer. It is concluded that further studies utilizing these observational data may reveal the structure and the evolution mechanism of tropical cloud clusters.

“…Solar radiation is strongly affected by clouds locating just over the observation point. We used only one grid data (about 10x10km area) over Momote, since typical topographic convections often observed on Manus Island were small in horizontal scale (about 10km) and showed slow movement (Takahashi and Uyeda, 1995; in this issue). Latent and sensible heat flux measurements by the eddy correlation method using an ultrasonic anemometer and an infrared gas analyzer were carried out a few times through the observation period when the surface wind was calm.…”

Section: Observations and Data Sourcesmentioning

confidence: 99%

“…One of the purposes of this study is to describe equatorial synoptic situations around Manus Island, Papua New Guinea, through the two month observation period by dual-Doppler radar. The radar observations found several kinds of convection around Manus Island such as squall-line type or topographic convection and stratiform rainfall from cloud clusters (e.g., Takahashi and Uyeda, 1995;Satoh et al, 1995;in this issue). The convective activity and the cycle for the development of clouds throughout the observation period were changeable.…”

Section: Introductionmentioning

confidence: 95%

Solar Radiation and Energy Flux Change on Manus Island, Papua New Guinea

Shirooka

Uyeda

1995

Self Cite

We observed global solar radiation changes through two months during the IOP of TOGA-COARE from 19 November 1992 to 19 January 1993 on Manus Island, Papua New Guinea, in the western tropical Pacific. The whole observation period was divided into four stages through consideration of the daily variations of solar radiation. Significant features of each period were also presented in terms of the activity of cloud convection derived from TBB data of GMS and zonal wind changes observed by a wind profiler.Surface winds were changeable throughout the observation period; however, an episodic strong westerly wind was observed from the end of December to early January. The most active stage of cloud convection, which was characterized by a decrease of solar radiation in the afternoon, was observed before the westerly wind episode. Morning convection was, however, prominent during the period of the strong westerly wind.A diurnal change of solar radiation was also compared with the change of latent and sensible heat fluxes obtained using the eddy correlation method. Energy fluxes on a ground surface indicated a quick response within about 30 minutes to solar radiation change. Latent and sensible heat fluxes were almost zero at nighttime, but the maximum value of latent and sensible heat fluxes in the daytime were about 270 and 200Wm-2, respectively.