Factors contributing to the onset of the Australian summer monsoon

Hung, Chih Wen; Yanai, Michio

doi:10.1256/qj.02.191

Cited by 107 publications

(107 citation statements)

References 39 publications

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“…These negative trends in water clarity coincided with the five years during which the GBR experienced strong La Niña conditions in 2007/08, 2008/09, 2010/11 and 2011/12 (Australian Bureau of Meteorology). In northeastern Australia, La Niña events are typically associated with an earlier onset of and a more vigorous summer monsoon, characterized by enhanced tropical cyclone activity and wetter summers [30][31][32][33]. The associated increased river discharge and vertical mixing is likely to be the main reason for the measured decrease in water clarity, especially of the shallow inner shelf waters.…”

Section: Resultsmentioning

confidence: 99%

Satellite-Derived Photic Depth on the Great Barrier Reef: Spatio-Temporal Patterns of Water Clarity

et al. 2012

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Detecting changes to the transparency of the water column is critical for understanding the responses of marine organisms, such as corals, to light availability. Long-term patterns in water transparency determine geographical and depth distributions, while acute reductions cause short-term stress, potentially mortality and may increase the organisms' vulnerability to other environmental stressors. Here, we investigated the optimal, operational algorithm for light attenuation through the water column across the scale of the Great Barrier Reef (GBR), Australia. We implemented and tested a quasi-analytical algorithm to determine the photic depth in GBR waters and matched regional Secchi depth (Z SD ) data to MODIS-Aqua (2002 and SeaWiFS (1997SeaWiFS ( -2010 satellite data. The results of the in situ Z SD /satellite data matchup showed a simple bias offset between the in situ and satellite retrievals. Using a Type II linear regression of log-transformed satellite and in situ data, we estimated Z SD and implemented the validated Z SD algorithm to generate a decadal satellite time series (2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012) values during the austral summer, most likely due to river runoff and increased vertical mixing, and a decline in water clarity between 2008-2012, reflecting a prevailing La Niña weather pattern. The decline in water clarity was most pronounced in the inshore area, where a significant decrease in mean inner shelf Z SD of 2.1 m (from 8.3 m to 6.2 m) occurred over the decade. Empirical Orthogonal Function Analysis determined the dominance of Mode 1 (51.3%), with the greatest variation in water clarity along the mid-shelf, reflecting the strong influence of oceanic intrusions on the spatio-temporal patterns of water clarity. The newly developed photic depth product has many potential applications for the GBR from water quality monitoring to analyses of ecosystem responses to changes in water clarity.

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Section: Resultsmentioning

confidence: 99%

Satellite-Derived Photic Depth on the Great Barrier Reef: Spatio-Temporal Patterns of Water Clarity

et al. 2012

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“…Independent of this study, Wang et al (2004) defined an Australian summer monsoon index based on 850 hPa zonal wind anomalies averaged over the region (0°-10°S, 120°-150°E), following the traditional notion employed by Australian meteorologists. Hung and Yanai (2004) used the zonal wind at 850 hPa within the region (2°-15°S, 115°-150°E) to describe the characteristics of TASM. Their TASM indices are strongly correlated with that of the present study, yielding correlation coefficients of 0.85 and 0.94 (Figure 10(a), (b)), respectively.…”

Section: Discussionmentioning

confidence: 99%

“…Previous studies have reported that the East Asian winter monsoon (EAWM) shows strong interdecadal variability (Wu and Zhang 2006;Zhou et al, 2007aZhou et al, , 2007bFigure 10. As in Figure 2, but for the normalized time series of (a) the TASM index defined by Wang et al (2004) and (b) the TASM index defined by Hung and Yanai (2004). This figure is available in colour online at wileyonlinelibrary.com/journal/joc Wu et al, 2009).…”

Section: Discussionmentioning

confidence: 99%

A possible cause of decreasing summer rainfall in northeast Australia

Li¹,

Feng²,

Li³

2011

Intl Journal of Climatology

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ABSTRACT:The NCEP/NCAR reanalysis and precipitation data from the Australian Bureau of Meteorology are used to analyse variability in rainfall during the austral summer (December-March, DJFM) in northeast Australia (NEA). NEA rainfall shows a marked decrease over the past 50 years, mainly in the austral summer. Our analysis reveals that the summer rainfall decrease in NEA is generally an interdecadal phenomenon. The declining trend has an imprint in the tropical Australian summer monsoon (TASM). Not only does TASM have a phase-to-phase influence on NEA summer rainfall at the interannual scale, it is also closely linked with interdecadal variation in NEA summer rainfall. Thus, the decrease in NEA at the interdecadal scale could be attributed to corresponding variation in TASM. Moreover, the coupled linkage between TASM and NEA summer rainfall appears to be largely independent of El Niño-Southern Oscillation. One possible reason for the interdecadal weakening trend in TASM is a sustained interdecadal warming trend in sea surface temperature (SST) over the Wharton Basin (100°-130°E, 20°-5°S). When the Wharton Basin is in a cold state, anomalous westerlies occur in the lower troposphere in the TASM region, and cyclonic circulation anomalies and rising flows occur in the low and middle troposphere over NEA, which are associated with a strong TASM situation, consequently favouring enhanced rainfall over NEA; the opposite occurs in the case of a warm Wharton Basin. SST over the Wharton Basin has shown a continuous warming trend over the past 60 years, contributing to the weakening of TASM and, consequently, a decrease in NEA summer rainfall.

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“…Q 1 and Q 2 have been widely used to reveal the role of diabatic heating in atmospheric processes such as the Madden-Julian Oscillation [e.g., Yanai et al, 2000;Lin et al, 2004], monsoons [e.g., Hung and Yanai, 2004;Garcia and Kayano, 2011], and energy and moisture budgets [e.g., Lin and Johnson, 1996b;Yang and Smith, 1999;Katsumata et al, 2011]. Neglecting ice processes, the equations of Q 1 and Q 2 can be written as…”

Section: Introductionmentioning

confidence: 99%

Three‐dimensional constrained variational analysis: Approach and application to analysis of atmospheric diabatic heating and derivative fields during an ARM SGP intensive observational period

Tang

Zhang

2015

JGR Atmospheres

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Atmospheric vertical velocities and advective tendencies are essential large-scale forcing data to drive single-column models (SCMs), cloud-resolving models (CRMs), and large-eddy simulations (LESs). However, they cannot be directly measured from field measurements or easily calculated with great accuracy. In the Atmospheric Radiation Measurement Program (ARM), a constrained variational algorithm (1-D constrained variational analysis (1DCVA)) has been used to derive large-scale forcing data over a sounding network domain with the aid of flux measurements at the surface and top of the atmosphere (TOA). The 1DCVA algorithm is now extended into three dimensions (3DCVA) along with other improvements to calculate gridded large-scale forcing data, diabatic heating sources (Q 1 ), and moisture sinks (Q 2 ). Results are presented for a midlatitude cyclone case study on 3 March 2000 at the ARM Southern Great Plains site. These results are used to evaluate the diabatic heating fields in the available products such as Rapid Update Cycle, ERA-Interim, National Centers for Environmental Prediction Climate Forecast System Reanalysis, Modern-Era Retrospective Analysis for Research and Applications, Japanese 55-year Reanalysis, and North American Regional Reanalysis. We show that although the analysis/reanalysis generally captures the atmospheric state of the cyclone, their biases in the derivative terms (Q 1 and Q 2 ) at regional scale of a few hundred kilometers are large and all analyses/reanalyses tend to underestimate the subgrid-scale upward transport of moist static energy in the lower troposphere. The 3DCVA-gridded large-scale forcing data are physically consistent with the spatial distribution of surface and TOA measurements of radiation, precipitation, latent and sensible heat fluxes, and clouds that are better suited to force SCMs, CRMs, and LESs. Possible applications of the 3DCVA are discussed.

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Factors contributing to the onset of the Australian summer monsoon

Cited by 107 publications

References 39 publications

Satellite-Derived Photic Depth on the Great Barrier Reef: Spatio-Temporal Patterns of Water Clarity

Satellite-Derived Photic Depth on the Great Barrier Reef: Spatio-Temporal Patterns of Water Clarity

A possible cause of decreasing summer rainfall in northeast Australia

Three‐dimensional constrained variational analysis: Approach and application to analysis of atmospheric diabatic heating and derivative fields during an ARM SGP intensive observational period

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