Karmakar, N., & Misra, V. (2019). The Relation of Intraseasonal Variations With Local Onset and Demise of the Indian Summer Monsoon. J. Geophys. Res. Atmos. , 124 (5), 2483–2506.
Abstract: Two of the most important hydroclimatic features of the Indian Summer Monsoon (ISM) rainfall are its onset/demise and Intraseasonal Oscillations (ISOs) manifested by the active‐break cycles. In this study, we aim to understand the quantitative association between these two phenomena. An objective definition of local onset/demise of the ISM based on more than a century‐long India Meteorological Department (IMD) rain‐gauge observation is taken into consideration. Using multichannel singular spectrum analysis (MSSA) we isolate northward propagating low‐ (20–60 days; LF‐ISO) and northwestward propagating high‐ (10–20 days; HF‐ISO) frequency ISOs from the daily ISM rainfall. Our results suggest that a large number of local onset (59%) and demise (62%) events occur during positive developing phases and positive decaying phases of two ISOs, respectively, with phase‐locking between LF‐ISO and HF‐ISO being particularly important. Local onset is largely associated with favorable phases of ISOs across India except for LF‐ISO over eastern India and HF‐ISO over western Ghats and central India (CI). We find that local demise is more coherent with the ISO phases, especially with HF‐ISO across the domain. We performed a case study to understand large‐scale association with the onset of the ISM over CI. In 44 of total 58 cases (1948–2005), when CI onset occurred during favorable LF‐ISO or HF‐ISO phase, they are either linked with a northward propagation of convection from the equator in LF‐ISO timescale (28 cases) or westward propagating structures from the western Pacific in HF‐ISO timescale (27 cases).
Katsaros, K. B., Bentamy, A., Bourassa, M., Ebuchi, N., Gower, J., Liu, W. T., et al. (2011). Climate Data Issues from an Oceanographic Remote Sensing Perspective. In D. Tang (Ed.), Remote Sensing of the Changing Oceans (pp. 7–32). Berlin: Springer.
Keeling, T. B. (2009). Modified JMA ENSO Index and Its Improvements to ENSO Classification . Master's thesis, Florida State University, Tallahassee, FL.
Abstract: El Nino-Southern Oscillation (ENSO) is a widely known phenomenon that affects many areas including the southeast United States. Over the southeast U.S. the Japan Meteorological Agency (JMA) ENSO index was modified to establish better classifications. In order to properly understand the effects of ENSO on this location a new approach was needed. Spatial resolution was improved by utilization of the PRISM dataset. PRISM provided monthly precipitation and temperature data over the contiguous US at 4 km resolution. Temporal resolution was improved by disregarding the traditional JMA definition of an ENSO year. The new definition requires six consecutive months of 0.5°C anomalies or larger to be listed as an ENSO event. By utilization of this definition, the ENSO index was modified to a monthly index from a yearly index. Many ENSO events begin in the summer months and end before the preceding September, therefore, an adoption of a monthly index is justified. Although several of the effects vary widely over the domain, there are a few prevalent patterns of ENSO effects. During warm phase, from November-April, wet conditions are seen in the coastal areas. July and August are both dry. From fall to spring, Florida and the Atlantic Coast are basically dry, however; the Mississippi River Valley doesn't appear wet as previous studies have indicted. Patterns of temperatures across the southeast are less variable than the precipitation. Differences between the ModJMA and JMA can be seen in several months, especially during late spring and early autumn. This result is not surprising based on the rigid definition of the JMA index. An interesting result presented itself throughout the study. Individual tropical storms can be identified with the increased resolution PRISM data provides. A state by state breakdown of the ModJMA conclusions provides regional summaries. The ModJMA better classifies ENSO periods and leads to a more precise impact of ENSO over the southeast United States.
Kelly, D. L., Letson, D., Nelson, F., Nolan, D. S., & Solís, D. (2012). Evolution of subjective hurricane risk perceptions: A Bayesian approach. Journal of Economic Behavior & Organization , 81 (2), 644–663.
Kelly, T. B. (2018). Spatial and interannual variability in export efficiency and the biological pump in an eastern boundary current upwelling system with substantial lateral advection . Master's thesis, Florida State University, Tallahassee, FL.
Kelly, T. B., Davison, P. C., Goericke, R., Landry, M. R., Ohman, M. D., & Stukel, M., R. (2019). The Importance of Mesozooplankton Diel Vertical Migration for Sustaining a Mesopelagic Food Web. FRONTIERS IN MARINE SCIENCE , 6 .
Abstract: We used extensive ecological and biogeochemical measurements obtained from quasi-Lagrangian experiments during two California Current Ecosystem Long-Term Ecosystem Research cruises to analyze carbon fluxes between the epipelagic and mesopelagic zones using a linear inverse ecosystem model (LIEM). Measurement constraints on the model include C-14 primary productivity, dilution-based microzooplankton grazing rates, gut pigment-based mesozooplankton grazing rates (on multiple zooplankton size classes), Th-234:U-238 disequilibrium and sediment trap measured carbon export, and metabolic requirements of micronekton, zooplankton, and bacteria. A likelihood approach (Markov Chain Monte Carlo) was used to estimate the resulting flow uncertainties from a sample of potential flux networks. Results highlight the importance of mesozooplankton active transport (i.e., diel vertical migration) in supplying the carbon demand of mesopelagic organisms and sequestering carbon dioxide from the atmosphere. In nine water parcels ranging from a coastal bloom to offshore oligotrophic conditions, mesozooplankton active transport accounted for 18-84% (median: 42%) of the total carbon transfer to the mesopelagic, with gravitational settling of POC (12-55%; median: 37%), and subduction (2-32%; median: 14%) providing the majority of the remainder. Vertically migrating zooplankton contributed to downward carbon flux through respiration and excretion at depth and via mortality losses to predatory zooplankton and mesopelagic fish (e.g., myctophids and gonostomatids). Sensitivity analyses showed that the results of the LIEM were robust to changes in nekton metabolic demand, rates of bacterial production, and mesozooplankton gross growth efficiency. This analysis suggests that prior estimates of zooplankton active transport based on conservative estimates of standard (rather than active) metabolism are likely too low.
Kelly, T. B., Goericke, R., Kahru, M., Song, H., & Stukel, M. R. (2018). CCE II: Spatial and interannual variability in export efficiency and the biological pump in an eastern boundary current upwelling system with substantial lateral advection. Deep Sea Research Part I: Oceanographic Research Papers , 140 , 14–25.
Abstract: Estimating interannual variability in carbon export is a key goal of many marine biogeochemical studies. However, due to variations in export mechanisms between regions, generalized models used to estimate global patterns in export often fail when used for intra-regional analysis. We present here a region-specific model of export production for the California Current Ecosystem (CCE) parameterized using intensive Lagrangian process studies conducted during El Niño-Southern Oscillation (ENSO) warm and neutral phases by the CCE Long-Term Ecological Research (LTER) program. We find that, contrary to expectations from prominent global algorithms, export efficiency (e-ratio = export / primary productivity) is positively correlated with temperature and negatively correlated with net primary productivity (NPP). We attribute these results to the substantial horizontal advection found within the region, and verify this assumption by using a Lagrangian particle tracking model to estimate water mass age. We further suggest that sinking particles in the CCE are comprised of a recently-produced, rapidly-sinking component (likely mesozooplankton fecal pellets) and a longer-lived, slowly-sinking component that is likely advected long distances prior to export. We determine a new algorithm for estimating particle export in the CCE from NPP (Export = 0.08 · NPP + 72 mg C m-2 d-1). We apply this algorithm to a two-decade long time series of NPP in the CCE to estimate spatial and interannual variability across multiple ENSO phases. Reduced export during the warm anomaly of 2014-2015 and El Niño 2015-2016 resulted primarily from decreased export in the coastal upwelling region of the CCE; the oligotrophic offshore region exhibited comparatively low seasonal and interannual variability in flux. The model resolves intra-regional patterns of in situ export measurements, and provides a valuable contrast to global export models.
Kelly, T. B., Goericke, R., Kahru, M., Song, H., & Stukel, M. R. (2018). CCE II: Spatial and interannual variability in export efficiency and the biological pump in an eastern boundary current upwelling system with substantial lateral advection. Deep Sea Research Part I: Oceanographic Research Papers , 140 , 14–25.
Kennedy, A. J., Griffin, M. L., Morey, S. L., Smith, S. R., & O'Brien, J. J. (2007). Effects of El Niño-Southern Oscillation on sea level anomalies along the Gulf of Mexico coast. J. Geophys. Res. , 112 (C5).
Kent, E. C., Rayner, N. A., Berry, D. I., Eastman, R., Grigorieva, V. G., Huang, B., et al. (2019). Observing Requirements for Long-Term Climate Records at the Ocean Surface. Front. Mar. Sci. , 6 , 441.
Abstract: Observations of conditions at the ocean surface have been made for centuries, contributing to some of the longest instrumental records of climate change. Most prominent is the climate data record (CDR) of sea surface temperature (SST), which is itself essential to the majority of activities in climate science and climate service provision. A much wider range of surface marine observations is available however, providing a rich source of data on past climate. We present a general error model describing the characteristics of observations used for the construction of climate records, illustrating the importance of multi-variate records with rich metadata for reducing uncertainty in CDRs. We describe the data and metadata requirements for the construction of stable, multi-century marine CDRs for variables important for describing the changing climate: SST, mean sea level pressure, air temperature, humidity, winds, clouds, and waves. Available sources of surface marine data are reviewed in the context of the error model. We outline the need for a range of complementary observations, including very high quality observations at a limited number of locations and also observations that sample more broadly but with greater uncertainty. We describe how high-resolution modern records, particularly those of high-quality, can help to improve the quality of observations throughout the historical record. We recommend the extension of internationally-coordinated data management and curation to observation types that do not have a primary focus of the construction of climate records. Also recommended is reprocessing the existing surface marine climate archive to improve and quantify data and metadata quality and homogeneity. We also recommend the expansion of observations from research vessels and high quality moorings, routine observations from ships and from data and metadata rescue. Other priorities include: field evaluation of sensors; resources for the process of establishing user requirements and determining whether requirements are being met; and research to estimate uncertainty, quantify biases and to improve methods of construction of CDRs. The requirements developed in this paper encompass specific actions involving a variety of stakeholders, including funding agencies, scientists, data managers, observing network operators, satellite agencies, and international co-ordination bodies.
