Problems of a Monsoon Ocean*

Ramage, C. S.

doi:10.1002/j.1477-8696.1968.tb03002.x

Cited by 10 publications

(5 citation statements)

References 8 publications

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“…Over the ocean, Yang and Smith () have shown that precipitation has a maximum between late evening and early morning. Nesbitt and Zipser () showed that the development of isolated convection occurs in the late morning and early afternoon over the islands (0800–1600 hr LT) and that during the evening and night many convective mesoscale systems grow (2000–0400 hr LT) over the Maritime Continent (region between the Indian and Pacific Oceans including the archipelagos of Indonesia, the Philippine Islands, New Guinea, Borneo, Malaysia, and the surrounding shallow seas) (Ramage, ). In winter, the Indian Ocean exhibits only one maximum which occurs in late evening–early morning (Yang and Smith, ).…”

Section: Methodsmentioning

confidence: 99%

“…The convergence of air masses at the ITCZ resolves into strong ascents, these wet masses expand under the effect of the heat, which can lead to the formation of large convective systems. The NET is a thalweg that exists near the Equator (Ramage, ; Hobbs, ). It is characterized by westerlies and a low‐pressure region near the Equator, and is located around 3°N and 3°S during austral winter and summer, respectively (Beucher, ).…”

Section: Seasonal Cloud Distribution Over the Southwest Indian Oceanmentioning

confidence: 99%

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Spatial and seasonal variability of clouds over the southwest Indian Ocean based on the DARDAR mask product

Vérèmes

Listowski

Delanoë

et al. 2019

Quart J Royal Meteoro Soc

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We present a characterization of the variability of clouds over the southwest Indian Ocean between 2007 and 2010. Cloud occurrence is derived from the DARDAR (raDAR/liDAR) mask, a synergistic product based on Cloud–Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) and CloudSat measurements. It provides a target classification for hydrometeors. We demonstrate that this product is suitable for studying the vertical, spatial and seasonal cloud distribution in the southwest Indian Ocean. The variability of cloud occurrence increases approaching the tropics: the average maximum amplitude of monthly occurrence is ∼7% between 30°S and 60°S and ∼14% between 10°S and 30°S. The 10–30°S latitudinal band exhibits the largest contrasts: summer (winter) total cloud occurrence is mainly driven by high‐ (low‐) level clouds. The vertical distribution of clouds differs on either side of 55°E and this is related to a land–ocean contrast and to large‐scale influence. In winter, east of 55°E, the maximum of cloud occurrence corresponds to warm and mixed‐phased precipitating clouds associated with the Mascarene High. In summer, west of 55°E, the vertical distribution of cloud occurrence is driven by deep convection associated with the InterTropical Convergence Zone and the Near Equatorial Trough. The vertical distribution of cloud occurrence shows an interannual variability that is related to El Niño events. The influence of other oscillation modes should be further investigated.

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Section: Methodsmentioning

confidence: 99%

Section: Seasonal Cloud Distribution Over the Southwest Indian Oceanmentioning

confidence: 99%

Spatial and seasonal variability of clouds over the southwest Indian Ocean based on the DARDAR mask product

Vérèmes

Listowski

Delanoë

et al. 2019

Quart J Royal Meteoro Soc

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“…Compared to other oceans, the central and the northern parts of the Indian Ocean exhibit the most pronounced seasonal change of surface conditions (see, for example, Ramage 1968) ; thus it seems valuable to look at the time variation in this region in closer detail. Monthly data on a 2' square basis represent a fairly high resolution both in time and space.…”

Section: (3)mentioning

confidence: 99%

Monthly Charts of Surface Wind Stress Curl Over the Indian Ocean

Hantel

1970

Mon. Wea. Rev.

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The surface wind stress curl is the forcing function in the equations of vertically integrated water transport of wind-driven ocean currents. Hence, i t has become a basic quantity in theoretical oceanography. As the time dependence of all important surface quantities in the Indian Ocean is stronger than in other oceans, it is valuable to look particularly a t the time variation in this region. This study presents monthly charts of the wind stress curl a t the surface of the Indian Ocean from its land boundaries up to 50" S. and from 20' E. to 116' E. Basic data were the monthly surface maps of the Koninklijk Nederlands Meteorologisch Instituut, derived from ship observations and given as 2" square means of the surface wind. The processing of the data is described in detail. I n particular, small-scale fluctuations arc objectively filtered out. While earlier compilations are usually on a coarser grid (seasonal and 5" square averages), the present data have a refined time and space resolution. Therefore, they allow onc to study more detailed structures. In particular, the charts show that the curl pattern in the Indian Ocean is not independent of longitude.

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“…The equatorward surge of cold air is predominantly a lower tropospheric phenomenon, and the acceleration of northeasterly winds is generally confined below 700 hPa and is associated with the southward intrusions of the Siberian–Mongolian high. It often causes sustained convection over the MC (Ramage, 1971; Wu and Chan, 1995; Chang et al ., 2006). As this cold air surges equatorward to the vicinity of the South China Sea (SCS), it is commonly known as the “cold surge” (CS) by most of the operational forecasters in the surrounding region.…”

Section: Introductionmentioning

confidence: 99%

Equatorial Rossby waves on cold surge days and their impact on rainfall

Diong¹,

Xavier

Woolnough

et al. 2023

Quart J Royal Meteoro Soc

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This study aims to understand the process that determines the regional rainfall distribution in the equatorial South China Sea (SCS) and its surrounding during the cold surge (CS) days by looking at the different vorticity phases of active equatorial Rossby (R1) waves and the dynamics of the CSs related to the R1 wave. The CS can be thought of as an anticyclonic outflow from midlatitude and behaves like a dispersive group of R1 meridional modes. From the study, it shows the vorticity of the R1 wave arranges itself in such a way that the anticyclonic phase is located to the west and the cyclonic phase is located to the east of the cold CS axis. The CS winds in the equatorial SCS occur early, remain longer, and possess a larger zonal component in the active cyclonic phase compared with the active anticyclonic phase. During the active cyclonic vorticity phase, the rainfall anomalies pattern in the equatorial SCS changes from a “tick‐mark‐like” pattern to a “V‐shape” pattern as a consequence of the westward propagation of the wave. The probability of rainfall increases near the centre of cyclonic vorticity, but for anticyclonic vorticity the probability increases in the southern part of the vorticity centre. There is both increased (decreased) intensity and probability of extreme rainfall events during the active cyclonic (anticyclonic) vorticity phase on CS days. Overall, the rainfall anomalies are largely dominated by changes in the intensity on wet days rather than the number of wet days. These changes indicate the roles of the R1 wave vorticity phase in the rainfall distribution during CS days. The timing of enhancement and suppression of rain will provide additional valuable information to help improve forecast extreme weather events.

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Problems of a Monsoon Ocean*

Cited by 10 publications

References 8 publications

Spatial and seasonal variability of clouds over the southwest Indian Ocean based on the DARDAR mask product

Spatial and seasonal variability of clouds over the southwest Indian Ocean based on the DARDAR mask product

Monthly Charts of Surface Wind Stress Curl Over the Indian Ocean

Equatorial Rossby waves on cold surge days and their impact on rainfall

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