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Anderson, B. T., & Perez, R. C. (2015). ENSO and non-ENSO induced charging and discharging of the equatorial Pacific. Clim Dyn, 45(9-10), 2309–2327.
Abstract: It is well established that variations in extratropical North Pacific wind stress fields can influence the state of the tropical Pacific 12-15 months prior to the maturation of boreal winter El Nio/Southern Oscillation (ENSO) events. While most research has focused on accompanying variations in the North Pacific trade winds and underlying sea surface temperatures that subsequently shift equatorward via anomalous air-sea interactions-e.g. meridional mode dynamics-observational and numerical model analyses indicate empirical and dynamical links exist between these same trade-wind variations and concurrent changes in subsurface temperatures across the equatorial Pacific, which can also serve as a key initiator of ENSO events. This paper shows that within an observationally-constrained ocean reanalysis dataset this initiation mechanism-termed the trade-wind charging (TWC) mechanism-is induced by the second leading mode of boreal winter zonal wind stress variability over the tropical Pacific and operates separately from ENSO-induced recharge/discharge of the equatorial Pacific heat content. The paper then examines the characteristics and evolution of the ENSO and TWC modes. Results indicate that the oceanic evolution for both modes is consistent with wind stress induced vertically-integrated, meridional mass transport into and out of the equatorial Pacific-i.e. a charging and discharging of the equatorial Pacific-despite having distinctly different wind stress anomaly patterns. The process-based similarity between these two modes of tropical Pacific wind stress variability suggests that both can produce a charging/discharging of the equatorial Pacific, however one (the ENSO mode) represents part of the ENSO cycle itself and the other (the TWC mode) represents a separate forcing mechanism of that cycle.
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Arcodia, M. C., Kirtman, B. P., & Siqueira, L. S. P. (2020). How MJO Teleconnections and ENSO Interference Impacts U.S. Precipitation. J. Climate, 33(11), 4621–4640.
Abstract: A composite analysis reveals how the Madden-Julian oscillation (MJO) impacts North American rainfall through perturbations in both the upper-tropospheric flow and regional low-level moisture availability. Upper-level divergence associated with the MJO tropical convection drives a quasi-stationary Rossby wave response to the midlatitudes. This forces a midlatitude upper-level dipolar geopotential height anomaly that is accompanied by a westward retraction of the jet stream and reduced rainfall over the central-eastern North Pacific. A reverse effect is found as the MJO propagates eastward across the Maritime Continent. These large differences in the extratropical upper-level flow, combined with anomalies in the regional supply of water vapor, have a profound impact on southeastern U.S. rainfall. The low-frequency variability, including that associated with ENSO, can modify the seasonal background flow (e.g., El Nino and La Nina basic states) affecting the distribution, strength, and propagation of the intraseasonal oscillation and the extratropical teleconnection patterns. The combined effects of the ENSO and the MJO signals result in both spatial and temporal patterns of interference and modulation of North American rainfall. The results from this study show that during a particular phase of an active MJO, the extratropical response can considerably enhance or mask the interannual ENSO signal in the United States, potentially resulting in anomalies of the opposite sign than that expected during a specific ENSO phase. Analyses of specific MJO events during an El Nino or La Nina episode reveal significant contributions to extreme events via constructive and destructive interference of the MJO and ENSO signals.
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Bjorndal, K. A., Bolten, A. B., Chaloupka, M., Saba, V. S., Bellini, C., Marcovaldi, M. A. G., et al. (2017). Ecological regime shift drives declining growth rates of sea turtles throughout the West Atlantic. Glob Change Biol, 23(11), 4556–4568. |
Bjorndal, K. A., Chaloupka, M., Saba, V. S., Diez, C. E., van Dam, R. P., Krueger, B. H., et al. (2016). Somatic growth dynamics of West Atlantic hawksbill sea turtles: a spatio-temporal perspective. Ecosphere, 7(5), e01279.
Abstract: Somatic growth dynamics are an integrated response to environmental conditions. Hawksbill sea turtles (Eretmochelys imbricata) are long-lived, major consumers in coral reef habitats that move over broad geographic areas (hundreds to thousands of kilometers). We evaluated spatio-temporal effects on hawksbill growth dynamics over a 33-yr period and 24 study sites throughout the West Atlantic and explored relationships between growth dynamics and climate indices. We compiled the largest ever data set on somatic growth rates for hawksbills -3541 growth increments from 1980 to 2013. Using generalized additive mixed model analyses, we evaluated 10 covariates, including spatial and temporal variation, that could affect growth rates. Growth rates throughout the region responded similarly over space and time. The lack of a spatial effect or spatio-temporal interaction and the very strong temporal effect reveal that growth rates in West Atlantic hawksbills are likely driven by region-wide forces. Between 1997 and 2013, mean growth rates declined significantly and steadily by 18%. Regional climate indices have significant relationships with annual growth rates with 0- or 1-yr lags: positive with the Multivariate El Nino Southern Oscillation Index (correlation = 0.99) and negative with Caribbean sea surface temperature (correlation = -0.85). Declines in growth rates between 1997 and 2013 throughout the West Atlantic most likely resulted from warming waters through indirect negative effects on foraging resources of hawksbills. These climatic influences are complex. With increasing temperatures, trajectories of decline of coral cover and availability in reef habitats of major prey species of hawksbills are not parallel. Knowledge of how choice of foraging habitats, prey selection, and prey abundance are affected by warming water temperatures is needed to understand how climate change will affect productivity of consumers that live in association with coral reefs.
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Bunge, L., & Clarke, A. J. (2014). On the Warm Water Volume and Its Changing Relationship with ENSO. J. Phys. Oceanogr., 44(5), 1372–1385.
Abstract: The interannual, equatorial Pacific, 20 degrees C isotherm depth variability since 1980 is dominated by two empirical orthogonal function (EOF) modes: the "tilt" mode, having opposite signs in the eastern and western equatorial Pacific and in phase with zonal wind forcing and El Nino-Southern Oscillation (ENSO) indices, and a second EOF mode of one sign across the Pacific. Because the tilt mode is of opposite sign in the eastern and western equatorial Pacific while the second EOF mode is of one sign, the second mode has been associated with the warm water volume (WWV), defined as the volume of water above the 20 degrees C isotherm from 5 degrees S to 5 degrees N, 120 degrees E to 80 degrees W. Past work suggested that the WWV led the tilt mode by about 2-3 seasons, making it an ENSO predictor. But after 1998 the lead has decreased and WWV-based predictions of ENSO have failed. The authors constructed a sea level-based WWV proxy back to 1955, and before 1973 it also exhibited a smaller lead. Analysis of data since 1980 showed that the decreased WWV lead is related to a marked increase in the tilt mode contribution to the WWV and a marked decrease in second-mode EOF amplitude and its contribution. Both pre-1973 and post-1998 periods of reduced lead were characterized by "mean" La Nina-like conditions, including a westward displacement of the anomalous wind forcing. According to recent theory, and consistent with observations, such westward displacement increases the tilt mode contribution to the WWV and decreases the second-mode amplitude and its WWV contribution.
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Burris, G., Elsner, J., & Doel, R. E. (2018). Plantation Records as a Source of Historical Weather and Agricultural Data. Southeastern Geographer, 58(4), 348–364.
Abstract: Plantation records from the southeastern United States have long been an important source for historical, social, and cultural narratives. However, they also represent an underutilized source for meteorological, environmental, and agricultural data from the antebellum period. This study has two goals. Firstly, we advocate for a more systematic application of these records for quantitative analysis. Secondly, we present some early results from such a study using the records of Shirley Plantation in Virginia. We show how these records can be mined for data on weather and agricultural activity and how their broader usefulness is extended with the inclusion of appropriate meta-data. Observations of weather conditions and crop responses to seasonal changes lend themselves to quantitative analysis that can improve our understanding of the local weather and climate of that period. We present a case study comparing last spring freeze date in this region from the late 1820s to 2010s and suggest that last spring freeze now occurs approximately 23 days earlier compared to approximately 200 years ago. We also include summaries of the response of specific crops and cultivars since this knowledge may help the farmers' of today adapt to changing weather conditions. While individual plantation records may have idiosyncratic limitations, plantation records, along with other types of detailed historical records, can still provide rich detail for specific locations or events. Plantation records are not limited to the southeastern US and include diverse geographic locations in less developed areas which were often the same areas were enslaved labor was exploited under the plantation system.
Keywords: CLIMATE-CHANGE; ENSO; VARIABILITY; PHENOLOGY; IMPACTS; SUGAR
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Cheng, C. - H., Nnadi, F., & Liou, Y. - A. (2015). A Regional Land Use Drought Index for Florida. Remote Sensing, 7(12), 17149–17167.
Abstract: Drought index is a useful tool to assess and respond to drought. However, current drought indices could not fully reveal land use effects and they have limitations in applications. Besides, El Niño Southern Oscillation (ENSO), strongly influences the climate of Florida. Hence, understanding ENSO patterns on a regional scale and developing a new land use drought index suitable for Florida are critical in agriculture and water resources planning and management. This paper presents a 32 km high resolution land use adapted drought index, which relies on five types of land uses (lake, urban, forest, wetland, and agriculture) in Florida. The land uses were obtained from National Centers for Environmental Prediction (NCEP) North American Regional Reanalysis (NARR) data from 1979 to 2002. The results showed that Bowen ratio responded to land use and could be used as an indicator to monitor drought events. Then, an innovative regional land use drought index was developed from the normalized Bowen ratio, which could reflect not only the level of severity during drought events resulting from land use effects, but also La Niña driven drought impacts. The proposed new index may help scientists answer the critical questions about drought effect on various land uses and potential feedbacks of changes in land use and land cover to climate.
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Cid-Serrano, L., Ramirez, S. M., Alfaro, E. J., & Enfield, D. B. (2015). Analysis of the Latin American west coast rainfall predictability using an ENSO index. Atmosfera, 28(3), 191–203.
Abstract: The objective of this study was to determine the probability of occurrence of wet or dry season events, by means of estimating latitudinal profiles for the association between El Nino Southern-Oscillation and the rainfall along the west coast of Central and South America. The analysis was performed using multinomial linear regression and multinomial logit regression models. We used monthly time series of the Pacific equatorial sea surface temperature (SST), the Nino 3.4 index, a sea level pressure index (SOI) and rainfall anomalies over a 2.5 x 2.5 degrees grid along the west coast of Central and South America, for latitudes starting at 25 degrees N through 45 degrees S, from 1951 to 2011. We defined an ENSO index (NSO) as predictor and rainfall as response. Data was grouped into seasons and then categorized into terciles to construct 3 x 3 non-symmetrical three way contingency tables. As results, we generated latitudinal profiles of the predictability (association) of rainfall for the west coast of Central and South America, using the ENSO phases as predictor.
Keywords: El Nino; logit regression; rainfall; ENSO
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Clarke, A. J. (2014). El Nino Physics and El Nino Predictability. Annu. Rev. Marine. Sci., 6(1), 79–99.
Abstract: Much of the year-to-year climate variability on the Earth is associated with
El Nino and the Southern Oscillation (ENSO). This variability is generated ˜
primarily by a coupled ocean-atmosphere instability near the eastern edge of
the western equatorial Pacific warm pool. Here, I discuss the physics of this
variability, including its phase locking to the seasonal cycle. ENSO growth
typically occurs from April/May to November, and by July the perturbation
is usually strong enough that it persists to the beginning of the following
year, when ENSO events usually end. Consequently, predicting ENSO is
easy from July to February but is more challenging across the April/May
transition to the next event. I discuss precursors of this transition and recent
results from dynamical and statistical models used for ENSO forecasting.
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DiNezio, P. N., Kirtman, B. P., Clement, A. C., Lee, S. - K., Vecchi, G. A., & Wittenberg, A. (2012). Mean Climate Controls on the Simulated Response of ENSO to Increasing Greenhouse Gases. J. Climate, 25(21), 7399–7420.
Abstract: Climate model experiments are analyzed to elucidate if and how the changes in mean climate in response to doubling of atmospheric CO2 (2xCO2) influence ENSO. The processes involved the development, transition, and decay of simulated ENSO events are quantified through a multimodel heat budget analysis. The simulated changes in ENSO amplitude in response to 2xCO2 are directly related to changes in the anomalous ocean heat flux convergence during the development, transition, and decay of ENSO events. The weakening of the Walker circulation and the increased thermal stratification, both robust features of the mean climate response to 2xCO2, play opposing roles in ENSO–mean climate interactions. Weaker upwelling in response to a weaker Walker circulation drives a reduction in thermocline-driven ocean heat flux convergence (i.e., thermocline feedback) and, thus, reduces the ENSO amplitude. Conversely, a stronger zonal subsurface temperature gradient, associated with the increased thermal stratification, drives an increase in zonal-current-induced ocean heat flux convergence (i.e., zonal advection feedback) and, thus, increases the ENSO amplitude. These opposing processes explain the lack of model agreement in whether ENSO is going to weaken or strengthen in response to increasing greenhouse gases, but also why ENSO appears to be relatively insensitive to 2xCO2 in most models.
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Elipot, S., & Beal, L. M. (2018). Observed Agulhas Current sensitivity to interannual and long-term trend atmospheric forcings. J. Climate, . |
Feng, J., Wu, Z., & Zou, X. (2014). Sea Surface Temperature Anomalies off Baja California: A Possible Precursor of ENSO. J. Atmos. Sci., 71(5), 1529–1537.
Abstract: Many recent studies have shown that observed El Nino-Southern Oscillation (ENSO) events are spatially and temporally diverse and that they have undergone changes in characteristics. To quantitatively capture these features, multidimensional ensemble empirical mode decomposition (MEEMD) is employed to isolate the temporal-spatial evolution of the sea surface temperature anomalies (SSTAs) on naturally separated time scales. An alternative Nino-3.4 index is also defined to reflect more on the interannual variability of equatorial Pacific SSTAs. Using this alternative index, 27 ENSO warm events are identified and the spatial-temporal evolution of each event is examined. It is found that a patch of SSTAs off Baja California appears to extend southwestward and reach the equatorial region near the international date line in about 1 year. This warm signal then amplifies and extends eastward, developing into an ENSO warm event. This type of development has been dominant in recent decades. For this type of ENSO warm event, it appears that SSTAs off Baja California are instrumental to ENSO development, possibly serving as a precursor of an ENSO event.
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Gelcer, E., Fraisse, C., Dzotsi, K., Hu, Z., Mendes, R., & Zotarelli, L. (2013). Effects of El Nino Southern Oscillation on the space-time variability of Agricultural Reference Index for Drought in midlatitudes. Agricultural and Forest Meteorology, 174-175, 110–128.
Abstract: Agriculture is an economic activity directly affected by drought. With the constant increase of food demand and the need for high efficiency in food production, drought effects gain attention. The Agricultural Reference Index for Drought (ARID) was developed to quantify drought and better understand its effect on agriculture. ARID values range from 0 to 1 where zero is transpiration occurring at potential rate and one is full water deficit. El Niño Southern Oscillation (ENSO) is the main factor of climate variability around the world and affects the climate of two states located in midlatitudes, Florida, USA and Rio Grande do Sul, Brazil. An historical assessment of the relationship between ARID and ENSO will assist with establishing the role played by ENSO in the seasonal variation of soil moisture, which is critical to drought forecasting based on ENSO. The main objectives of this study were to investigate ARID's temporal and spatial variability in Florida and Rio Grande do Sul, and provide an assessment of ENSO-induced potential anomalies in ARID. Daily ARID values in Florida were calculated using data obtained from the National Weather Service COOP (Cooperative Observer Program) weather stations. In Rio Grande do Sul, ARID was calculated using daily weather data from the Instituto Nacional de Meteorologia (INMET) weather stations, Brazil. Daily ARID values were compiled into monthly averages and categorized according to ENSO phase based on the Multivariate ENSO Index (MEI). Results showed that typical ARID values for both regions vary throughout the year. The highest values were observed in the warm season due to increased evapotranspiration. During this period, ARID values varied from 0.3 to 0.8 in Florida and 0.2 to 0.7 in Rio Grande do Sul. In the cold period, South Florida had the highest ARID values, varying from 0.3 to 0.7, while for the rest of state and Rio Grande do Sul the values varied from 0 to 0.5. ENSO showed stronger influence from November to March in Florida, and November and May in Rio Grande do Sul. For both regions, El Niño caused ARID values below normal, indicating higher soil moisture while during La Niña the values were above normal. This study contributes to establish historical ARID records across the southeastern United States and southern Brazil, and can assist farmers to adjust management practices according to expected water stress conditions.
Keywords: ENSO; El Nino; ARID; Drought index; Florida; Rio Grande do Sul
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Gilford, D. M., Smith, S. R., Griffin, M. L., & Arguez, A. (2013). Southeastern U.S. Daily Temperature Ranges Associated with the El Nino-Southern Oscillation. J. Appl. Meteor. Climatol., 52(11), 2434–2449.
Abstract: The daily temperature range (DTR; daily maximum temperature minus daily minimum temperature) at 290 southeastern U.S. stations is examined with respect to the warm and cold phases of the El Niño�Southern Oscillation (ENSO) for the period of 1948�2009. A comparison of El Niño and La Niña DTR distributions during 3-month seasons is conducted using various metrics. Histograms show each station�s particular distribution. To compare directly the normalized distributions of El Niño and La Niña, a new metric (herein called conditional ratio) is produced and results are evaluated for significance at 95% confidence with a bootstrapping technique. Results show that during 3-month winter, spring, and autumn seasons DTRs above 29°F (16.1°C) are significantly more frequent during La Niña events and that DTRs below 15°F (8.3°C) are significantly more frequent during El Niño events. It is hypothesized that these results are associated spatially with cloud cover and storm tracks during each season and ENSO phase. Relationships between DTRs and ENSO-related relative humidity are examined. These results are pertinent to the cattle industry in the Southeast, allowing ranchers to plan for and mitigate threats posed by periods of low DTRs associated with the predicted phase of ENSO.
Keywords: Climate variability; Climatology; ENSO; Surface temperature; Climate records
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Infanti, J. M., & Kirtman, B. P. (2016). North American rainfall and temperature prediction response to the diversity of ENSO. Clim Dyn, 46(9-10), 3007–3023.
Abstract: Research has shown that there is significant diversity in the location of the maximum sea surface temperature anomaly (SSTA) associated with the El Nio Southern Oscillation (ENSO). In one extreme, warm SSTA peak near the South American coast (often referred to as Eastern Pacific of EP El Nio), and at the other extreme, warm SSTA peak in the central Pacific (Central Pacific or CP El Nio). Due to the differing tropical Pacific SSTA and precipitation structure, there are differing extratropical responses, particularly over North America. Recent work involving the North American Multi-Model Ensemble (NMME) system for intra-seasonal to inter-annual prediction on prediction of the differences between El Nio events found excess warming in the eastern Pacific during CP El Nio events. This manuscript investigates the ensemble and observational agreement of the NMME system when forecasting the North American response to the diversity of ENSO, focusing on regional land-based 2-meter temperature and precipitation. NMME forecasts of North American precipitation and T2m agree with observations more often during EP events. Ensemble agreement of NMME forecasts is regional. For instance, ensemble agreement in Southeast North America demonstrates a strong connection to NINO3 precipitation and SSTA amplitude during warm ENSO events. Ensemble agreement in Northwest North America demonstrates a weak connection to NINO4 precipitation and SSTA amplitude during warm ENSO events. Still other regions do not show a strong connection between ensemble agreement and strength of warm ENSO events.
Keywords: ENSO diversity; El Nino; Teleconnections; North America; Climate prediction
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Infanti, J. M., Kirtman, B. P., Aumen, N. G., Stamm, J., & Polsky, C. (2020). Aligning Climate Models With Stakeholder Needs: Advances in Communicating Future Rainfall Uncertainties for South Florida Decision Makers. Earth and Space Science, 7(7).
Abstract: Changes in future precipitation are of great importance to climate data users in South Florida. A recent U.S. Geological Survey workshop, "Increasing Confidence in Precipitation Projections for Everglades Restoration," highlighted a gap between standard climate model outputs and the climate information needs of some key Florida natural resource managers. These natural resource managers (hereafter broadly defined as "climate data users") need more tailored output than is commonly provided by the climate modeling community. This study responds to these user needs by outlining and testing an adaptable methodology to select output from ensemble climate-model simulations based on user-defined precipitation drivers, using statistical methods common across scientific disciplines. This methodology is developed to provide a "decision matrix" that guides climate data users to specify the subset of models most important to their work based on each user's season (winter, summer, and annual) and the condition (dry, wet, neutral, and no threshold events) of interest. The decision matrix is intended to better communicate the subset of models best representing precipitation drivers. This information could increase users' confidence in climate models as a resource for natural resource planning and can be used to direct future dynamical downscaling efforts. This methodology is based in dynamical processes controlling precipitation via remote and local teleconnections. We also suggest that future climate studies in South Florida include high-resolution climate model runs (i.e., ocean eddy resolving) in conjunction with dynamical downscaling to adequately capture precipitation variability.
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Johnson, N. T., Martinez, C. J., Kiker, G. A., & Leitman, S. (2013). Pacific and Atlantic sea surface temperature influences on streamflow in the Apalachicola-Chattahoochee-Flint river basin. Journal of Hydrology, 489, 160–179.
Abstract: Large scale climate phenomena can provide valuable information for regional climate and streamflow in many parts of the world. Several climate phenomena may impact a given area and their value for providing information on streamflow is dependent on first establishing the local relationship. This study was conducted to establish the individual and coupled impacts of the El Nino-Southern Oscillation (ENSO), Pacific Decadal Oscillation (PDO), and Atlantic Multidecadal Oscillation (AMO) on streamflow in the Apalachicola-Chattahoochee-Flint (ACF) river basin. Differences in annual and seasonal streamflow using two unimpaired streamflow datasets based on the phase(s) of ENSO, the PDO, and the AMO were evaluated using the nonparametric rank-sum test. Few statistical differences were found for the individual impacts of ENSO and the PDO on annual and seasonal streamflow; differences based on ENSO were largely confined to the southern portion of the basin. Significant differences in annual streamflow based on the AMO were largely confined to the northern half of the basin. Differences in seasonal streamflow based on the AMO were found for much of the year in the northern portion of the basin but were confined to the winter season in the southern portion. Significant differences in annual and seasonal streamflow were found between the La Nina/positive AMO phase and the El Nino/negative AMO phase, between the positive AMO/negative PDO phase and the negative AMO/negative PDO phase, and there appears to be a modulation of the impacts of La Nina by the phase of the AMO. A greater number of stations and a greater magnitude of significant differences were found for the coupled impacts than for the individual impacts of ENSO, the PDO, and the AMO; indicating the importance of the coupled impacts on regional streamflow when establishing the role of annual, decadal, and multidecadal climate variability.
Keywords: Streamflow; Climate variability; ENSO; AMO; PDO
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Katsaros, K. B., A. Bentamy, M. Bourassa, N. Ebuchi, J. Gower, W. T. Liu, and S. Vignudelli. (2011). Climate Data Issues from an Oceanographic Remote Sensing Perspective. In Remote Sensing of the Changing Oceans (pp. 7–32). Berlin, Germany: Springer-Verlag.
Abstract: In this chapter we review several climatologically important variables
with a history of observation from spaceborne platforms. These include sea surface
temperature and wind vectors, altimetric estimates of sea surface height, energy and
water vapor fluxes at the sea surface, precipitation over the ocean, and ocean color.
We then discuss possible improvements in sampling for climate and climate change
definition. Issues of consistency of different data sources, archiving and distribution
of these types of data are discussed. The practical prospect of immediate international
coordination through the concept of virtual constellations is discussed and
applauded.
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Keener, V. W., Ingram, K. T., Jacobson, B., & Jones, J. W. (2007). Effects of El Nino/Southern Oscillation on simulated phosphorus loading in south Florida. Transactions of the Asabe, , 2081–2089.
Abstract: The El Nino/Southern Oscillation (ENSO) is a global climate phenomenon with strong effects on Florida's weather patterns. ENSO has been shown to have predictable effects on streamflow, rainfall, and crop yield; however, the relationship between N and P loading and ENSO has not been previously explored. Nutrient loads for a Lake Okeechobee sub-basin for 1965-2001 were simulated with the Watershed Assessment Model (WAM) and compared to measured P loads. The NS coefficients for simulated and measured monthly P loads were 0.73 for the calibration period and 0.63 for the validation period, which indicates "satisfactory" to "good" model performance. With a probable error range (PER) of +/-27.8% for measured P loads, the modified NS coefficients increased to 0.94 for the calibration period and 0.93 for the validation period. Results showed that ENSO strongly affected simulated seasonal and monthly phosphorus runoff. El Nino years produced seasonal peak loads of P runoff into Lake Okeechobee significant at the 99% level during the spring (February April), which indicates dominance of positive load anomalies. La Nina years produced significant seasonal peak loads in the summer (May-July) but with much greater variability in loads. Neutral years exhibited less predictable seasonal loading, although simulated P loads were generally similar to measured long-term means. Nutrient loading patterns during specific ENSO phases were comparable to previously explored precipitation and streamflow patterns in south Florida. This research has potential for use by land and water managers who can add short-term ENSO-based climate forecasts to their toolbox for reducing nutrient runoff.
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Krishnamurthy, V., & Misra, V. (2011). Daily atmospheric variability in the South American monsoon system. Clim. Dyn., 37(3-4), 803–819.
Abstract: The space-time structure of the daily atmospheric variability in the South American monsoon system has been studied using multichannel singular spectrum analysis of daily outgoing longwave radiation. The three leading eigenmodes are found to have low-frequency variability while four other modes form higher frequency oscillations. The first mode has the same time variability as that of El Nino-Southern Oscillation (ENSO) and exhibits strong correlation with the Pacific sea surface temperature (SST). The second mode varies on a decadal time scale with significant correlation with the Atlantic SST suggesting an association with the Atlantic multidecadal oscillation (AMO). The third mode also has decadal variability but shows an association with the SST of the Pacific decadal oscillation (PDO). The fourth and fifth modes describe an oscillation that has a period of about 165 days and is associated with the North Atlantic oscillation (NAO). The sixth and seventh modes describe an intraseasonal oscillation with a period of 52 days which shows strong relation with the Madden-Julian oscillation. There exists an important difference in the variability of convection between Amazon River Basin (ARB) and central-east South America (CESA). Both regions have similar variations due to ENSO though with higher magnitude in ARB. The AMO-related mode has almost identical variations in the two regions, whereas the PDO-related mode has opposite variations. The interseasonal NAO-related mode also has variations of opposite sign with comparable magnitudes in the two regions. The intraseasonal variability over the CESA is robust while it is very weak over the ARB region. The relative contributions from the low-frequency modes mainly determine the interannual variability of the seasonal mean monsoon although the interseasonal oscillation may contribute in a subtle way during certain years. The intraseasonal variability does not seem to influence the interannual variability in either region.
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