Pantina, P. (2010). Characterizing the Variability of the Indian Monsoon: Changes in Evaporative Sources for Summertime Rainfall Events. Master's thesis, Florida State University, Tallahassee, FL.
Abstract: This study focuses on the interannual and intraseasonal variability of evaporative sources for rainfall events during the Indian monsoon. The monsoon is an important part of the economy and lifestyle in India, thus, any improvements in our understanding of its mechanisms would be directly beneficial to society. We first discuss the use of evaporative sources for rainfall events as an important tool to help increase our knowledge of the variations of the monsoon. We then outline the variability of the monsoon on an interannual (wet and dry years) and intraseasonal (active and break periods) time scale. We use three reanalyses (NCEP-R2, CFSR, and MERRA) and an IMD gridded rainfall dataset to trace the location and strength of evaporative sources via a quasi-isentropic back trajectory program. The program uses reanalysis winds and evaporation, among other parameters, to estimate these sources back in time. We discuss the differences in parameters between the datasets on a seasonal, interannual, and intraseasonal time scale. We then thoroughly investigate the strength and location of evaporative sources between datasets on interannual and intraseasonal time scales, and we attempt to explain the variations by analyzing the differences in the input parameters and circulation mechanisms themselves. The study finds that the evaporative sources for given interannual or intraseasonal rainfall events do vary in strength and location. Interannually, the strongest change in evaporative source occurs over central India and the Arabian Sea, suggesting that the overall monsoon flow contributes moisture for Indian rainfall on this time scale. Intraseasonally, the strongest change in evaporative source occurs over the Bay of Bengal, suggesting that low pressure systems contribute moisture for Indian rainfall on this time scale. All three reanalyses yield similar fields of evaporative source. We conclude that accurate prediction of the Indian monsoon requires improved understanding of both interannual and intraseasonal oscillations since the sources of moisture for these events are unique.
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Parfitt, R., Ummenhofer, C. C., Buckley, B. M., Hansen, K. G., & D'Arrigo, R. D. (2020). Distinct seasonal climate drivers revealed in a network of tree-ring records from Labrador, Canada. Clim Dyn, 54(3-4), 1897–1911.
Abstract: Traditionally, high-latitude dendroclimatic studies have focused on measurements of total ring width (RW), with the maximum density of the latewood (MXD) serving as a complementary variable. Whilst MXD has typically improved the strength of the growing season climate connection over that of RW, its measurements are costly and time-consuming. Recently, a less costly and more time-efficient technique to extract density measurements has emerged, based on lignin's propensity to absorb blue light. This Blue Intensity (BI) methodology is based on image analyses of finely-sanded core samples, and the relative ease with which density measurements can be extracted allows for significant increases in spatio-temporal sample depth. While some studies have attempted to combine RW and MXD as predictors for summer temperature reconstructions, here we evaluate a systematic comparison of the climate signal for RW and latewood BI (LWBI) separately, using a recently updated and expanded tree ring database for Labrador, Canada. We demonstrate that while RW responds primarily to climatic drivers earlier in the growing season (January-April), LWBI is more responsive to climate conditions during late spring and summer (May-August). Furthermore, RW appears to be driven primarily by large-scale atmospheric dynamics associated with the Pacific North American pattern, whilst LWBI is more closely associated with local climate conditions, themselves linked to the behaviour of the Atlantic Multidecadal Oscillation. Lastly, we demonstrate that anomalously wide or narrow growth rings consistently respond to the same climate drivers as average growth years, whereas the sensitivity of LWBI to extreme climate conditions appears to be enhanced.
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Patten, J. M., Smith, S. R., & O'Brien, J. J. (2003). Impacts of ENSO on Snowfall Frequencies in the United States. Wea. Forecasting, 18(5), 965–980.
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Pegion, P. J. (1999). Objectively-derived daily Winds from satellite scatterometer. Master's thesis, Florida State University, Tallahassee, FL.
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Pegion, P. J., Bourassa, M. A., Legler, D. M., & O'Brien, J. J. (2000). Objectively Derived Daily “Winds” from Satellite Scatterometer Data. Mon. Wea. Rev., 128(9), 3150–3168.
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Penduff, T., Barnier, B., Béranger, K., & Verron, J. (2001). Comparison of near-surface mean and eddy flows from two numerical models of the South Atlantic Ocean. J. Geophys. Res., 106(C8), 16857–16867.
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Penduff, T., Barnier, B., Dewar, W. K., & O'Brien, J. J. (2004). Dynamical Response of the Oceanic Eddy Field to the North Atlantic Oscillation: A Model-Data Comparison. J. Phys. Oceanogr., 34(12), 2615–2629.
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Penduff, T., Barnier, B., Kerbiriou, M. - A., & Verron, J. (2002). How Topographic Smoothing Contributes to Differences between the Eddy Flows Simulated by Sigma- and Geopotential-Coordinate Models. J. Phys. Oceanogr., 32(1), 122–137.
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Penduff, T., Brasseur, P., Testut, C. - E., Barnier, B., & Verron, J. (2001). A four-year eddy-permitting assimilation of sea-surface temperature and altimetric data in the South Atlantic Ocean. Journal of Marine Research, 60(6), 805–833.
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Penduff, T., de Verdière, A. C., & Barnier, B. (2001). General circulation and intergyre dynamics in the eastern North Atlantic from a regional primitive equation model. J. Geophys. Res., 106(C10), 22313–22329.
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