The diurnal cycle of rainfall over New Guinea in convection-permitting WRF simulations

Hassim, Muhammad E. E.; Lane, Todd P.; Grabowski, Wojciech W.

doi:10.5194/acp-16-161-2016

Cited by 92 publications

(125 citation statements)

References 28 publications

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“…Neither the pattern nor the magnitude is altered meaningfully between the two simulations. These results suggest that the diurnal cycle characteristics are not sensitive to the orography over Hainan Island, although many previous studies demonstrated that the orography can play an important role in the precipitation over other islands (Sobel et al, 2011;Hassim et al, 2016;Barthlott and Kirshbaum, 2013).…”

Section: The Simulated Diurnal Cycle and The Influence Of The Orographymentioning

confidence: 57%

“…With CMORPH data and regional climate model simulations, Qian (2008) found that sea-breeze convergence, mountain-valley winds and cumulus merger process are the predominant reasons for the diurnal precipitation cycles, while the underrepresentation of islands and terrain results in an underestimation of precipitation. Hassim et al (2016) examined the diurnal cycle of rainfall over New Guinea with a 4 km convection-permitting WRF model. They found the importance of sea breeze in the initiation of rainfall but focused on large-scale atmospheric properties preferred by the propagation of systems offshore at night.…”

Section: Introductionmentioning

confidence: 99%

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The influence of sea- and land-breeze circulations on the diurnal variability in precipitation over a tropical island

et al. 2017

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Abstract. This study examines the diurnal variation in precipitation over Hainan Island in the South China Sea using gauge observations from 1951 to 2012 and Climate Prediction Center MORPHing technique (CMORPH) satellite estimates from 2006 to 2015, as well as numerical simulations. The simulations are the first to use climatological mean initial and lateral boundary conditions to study the dynamic and thermodynamic processes (and the impacts of land-sea breeze circulations) that control the rainfall distribution and climatology. Precipitation is most significant from April to October and exhibits a strong diurnal cycle resulting from land-sea breeze circulations. More than 60 % of the total annual precipitation over the island is attributable to the diurnal cycle with a significant monthly variability. The CMORPH and gauge datasets agree well, except that the CMORPH data underestimate precipitation and have a 1 h peak delay. The diurnal cycle of the rainfall and the related landsea breeze circulations during May and June were well captured by convection-permitting numerical simulations with the Weather Research and Forecasting (WRF) model, which were initiated from a 10-year average ERA-Interim reanalysis. The simulations have a slight overestimation of rainfall amounts and a 1 h delay in peak rainfall time. The diurnal cycle of precipitation is driven by the occurrence of moist convection around noontime owing to low-level convergence associated with the sea-breeze circulations. The precipitation intensifies rapidly thereafter and peaks in the afternoon with the collisions of sea-breeze fronts from different sides of the island. Cold pools of the convective storms contribute to the inland propagation of the sea breeze. Generally, precipitation dissipates quickly in the evening due to the cooling and stabilization of the lower troposphere and decrease of boundary layer moisture. Interestingly, the rather high island orography is not a dominant factor in the diurnal variation in precipitation over the island.

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Section: The Simulated Diurnal Cycle and The Influence Of The Orographymentioning

confidence: 57%

Section: Introductionmentioning

confidence: 99%

The influence of sea- and land-breeze circulations on the diurnal variability in precipitation over a tropical island

et al. 2017

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“…It is one of the wettest places on Earth, and the high latent heat release from organized convective activity in the region influences global circulation and climate via downstream Rossby wave responses (Jin and Hoskins 1995;Neale and Slingo 2003). On a diurnal time scale, precipitation forms over the islands in the afternoon as a result of a seabreeze convergence mechanism and propagates offshore overnight through the reversal of the sea breeze and coupling to gravity waves (Saito et al 2001;Mori et al 2004;Qian 2008;Love et al 2011;Hassim et al 2016).…”

Section: Introductionmentioning

confidence: 99%

“…While there are known issues with TRMM in the MC region, it is unlikely that the model-observation differences are solely due to TRMM uncertainties. Wet biases from high rainfall rates in CP configurations of the MetUM, especially over high orography, are a known issue in a number of regions of the world (Birch et al 2014a;Kendon et al 2012) and also in other CP models (e.g., Hassim et al 2016), and this bias is the subject of ongoing research at the Met Office.…”

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confidence: 99%

Scale Interactions between the MJO and the Western Maritime Continent

et al. 2016

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State-of-the-art regional climate model simulations that are able to resolve key mesoscale circulations are used, for the first time, to understand the interaction between the large-scale convective environment of the MJO and processes governing the strong diurnal cycle over the islands of the Maritime Continent (MC). Convection is sustained in the late afternoon just inland of the coasts because of sea breeze convergence. Previous work has shown that the variability in MC rainfall associated with the MJO is manifested in changes to this diurnal cycle; land-based rainfall peaks before the active convective envelope of the MJO reaches the MC, whereas oceanic rainfall rates peak while the active envelope resides over the region. The model simulations show that the main controls on oceanic MC rainfall in the early active MJO phases are the large-scale environment and atmospheric stability, followed by high oceanic latent heat flux forced by high near-surface winds in the later active MJO phases. Over land, rainfall peaks before the main convective envelope arrives (in agreement with observations), even though the large-scale convective environment is only moderately favorable for convection. The causes of this early rainfall peak are strong convective triggers from land-sea breeze circulations that result from high surface insolation and surface heating. During the peak MJO phases cloud cover increases and surface insolation decreases, which weakens the strength of the mesoscale circulations and reduces land-based rainfall, even though the large-scale environment remains favorable for convection at this time. Hence, scale interactions are an essential part of the MJO transition across the MC.

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“…According to investigations of moist convection off mountainous coasts in different geographical regions, combinations of topographic effects, diurnally induced circulations and waves, and discontinuities in surface roughness between the land and ocean probably determine the nature of coastal convection (Garrett 1980;Houze et al 1981;Grossman and Durran 1984;Liberti et al 2001;Mapes et al 2003;Colle and Yuter 2007;Hassim et al 2016;Vincent and Lane 2016). According to investigations of moist convection off mountainous coasts in different geographical regions, combinations of topographic effects, diurnally induced circulations and waves, and discontinuities in surface roughness between the land and ocean probably determine the nature of coastal convection (Garrett 1980;Houze et al 1981;Grossman and Durran 1984;Liberti et al 2001;Mapes et al 2003;Colle and Yuter 2007;Hassim et al 2016;Vincent and Lane 2016).…”

Section: Introductionmentioning

confidence: 99%

Formation and Maintenance of a Long-Lived Taiwan Rainband during 1–3 March 2003

Lin

2017

Journal of the Atmospheric Sciences

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Taiwan rainbands (TRs), defined here as convective lines, which form off the mountainous eastern coast of Taiwan under weakly synoptically forced weather conditions, are a well-known mesoscale phenomenon, but their formative processes remain the subject of debate. This study uses surface and radar observations within the coastal zone of eastern Taiwan and NCEP reanalysis data to document a long-lived TR with a lifetime of ;36 h during 1-3 March 2003 to advance the current general understanding of mechanisms responsible for the TR's formation and maintenance. Detailed analyses indicate that the rainband was initiated by convergence that was produced as low-level environmental northeasterly/easterly onshore flow encountered topographically blocked northerlies that developed nearshore. The northerly blocked flow was observed to weaken and subsequently dissipate because of changing synoptic pressure patterns that caused prevailing southeasterlies/southerlies at low levels. However, colder nearshore air that resulted from the combined effects of orographic blocking, the evaporation of the TR's precipitation, and radiative cooling over coastal land continued to persist and acted to provide a continuing source of lifting for the subsequent maintenance of moist convection. Temporal variations in the precipitation intensity of the studied TR were also shown to be consistent with the theoretical prediction of the interaction between the cold pool and ambient vertical shear. This study suggests that multiple precipitation mechanisms, which involve interactions of diurnally, topographically, and convectively generated circulations along the mountainous coast, may operate and contribute to the longevity of a TR event under suitable circumstances, such as the rapidly evolving synoptic flow observed in the present case.

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The diurnal cycle of rainfall over New Guinea in convection-permitting WRF simulations

Cited by 92 publications

References 28 publications

The influence of sea- and land-breeze circulations on the diurnal variability in precipitation over a tropical island

The influence of sea- and land-breeze circulations on the diurnal variability in precipitation over a tropical island

Scale Interactions between the MJO and the Western Maritime Continent

Formation and Maintenance of a Long-Lived Taiwan Rainband during 1–3 March 2003

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