scholarly journals A Simple Nonlinear and End-Member-Free Approach for Obtaining Ocean Remineralization Patterns

2017 ◽  
Vol 34 (11) ◽  
pp. 2443-2455
Author(s):  
Patricia De La Fuente ◽  
Josep L. Pelegrí ◽  
Antonio Canepa ◽  
Marc Gasser ◽  
Francisco Domínguez ◽  
...  
Keyword(s):  
Polynomial Regression ◽  
Water Masses ◽  
Stoichiometric Ratio ◽  
Equatorial Atlantic ◽  
Oxygen Utilization ◽  
Fluorescent Dissolved Organic Matter ◽  
Equatorial Atlantic Ocean ◽  
Nonlinear Mixing ◽  
Local Variability

AbstractThe variability of a biogeochemical property in the ocean is the outcome of both nonconservative (such as respiration and photosynthesis) and conservative (mixing of water masses with distinct concentrations at origin) processes. One method to separate both contributions is based on a multiple regression of the biogeochemical property in terms of temperature θ and salinity S as conservative proxies of water masses. This regression delivers the variability related to the conservative fraction and hence allows for identifying the residual as the biogeochemical anomaly. Here, the standard multiple linear regression (MLR) method, which assumes that water masses mix locally and linearly, is compared with a nonlinear polynomial regression (PR) over the entire (θ, S) space. The PR method has two important advantages over MLR: allows for simultaneous nonlinear mixing of all water masses and does not require knowing the end-member water types. Both approaches are applied to data along 7.5°N in the equatorial Atlantic Ocean, and the biogeochemical anomalies are calculated for humic-like fluorescent dissolved organic matter, apparent oxygen utilization, and nitrate—all of them related through in situ remineralization processes. The goodness of both approaches is assessed by analyzing the linear dependence and the coefficient of correlation between the anomalies. The results show that the PR method can be applied over the entire water column and yet retains the local variability associated with nonconservative processes. The potential of the PR approach is also illustrated by calculating the oxygen–nitrate stoichiometric ratio for the entire 7.5°N transatlantic section.

scholarly journals Sedimentary supply of humic-like fluorescent dissolved organic matter and its implication for chemoautotrophic microbial activity in the Izu-Ogasawara Trench

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
M. Shigemitsu ◽  
T. Yokokawa ◽  
H. Uchida ◽  
S. Kawagucci ◽  
A. Murata
Keyword(s):  
Organic Matter ◽  
Community Structure ◽  
Dissolved Organic Matter ◽  
Oxygen Utilization ◽  
Fluorescent Dissolved Organic Matter ◽  
Vertical Distributions ◽  
The Difference ◽  
The Relationship ◽  
Apparent Oxygen Utilization

AbstractMicrobial community structure in the hadal water is reported to be different from that in the upper abyssal water. However, the mechanism governing the difference has not been fully understood. In this study, we investigate the vertical distributions of humic-like fluorescent dissolved organic matter (FDOMH), chemoautotrophic production, apparent oxygen utilization (AOU), and N* in the Izu-Ogasawara Trench. In the upper abyssal waters (< 6000 m), FDOMH has a significantly positive correlation with AOU; FDOMH deviates from the relationship and increases with depth without involving the increment of AOU in the hadal waters. This suggests that FDOMH is transferred from the sediments to the hadal waters through pore water, while the FDOMH is produced in situ in the upper abyssal waters. Chemoautotrophic production and N* increases and decreases with depth in the hadal waters, respectively. This corroborates the effluxes of dissolved substances, including dissolved organic matter and electron donors from sediments, which fuels the heterotrophic/chemoautotrophic microbial communities in the hadal waters. A simple box model analysis reveals that the funnel-like trench topography facilitates the increase in dissolved substances with depth in the hadal waters, which might contribute to the unique microbiological community structure in these waters.

scholarly journals Estudo de Frequência da Ocorrência de Rajada de Vento e seu Papel na Segurança das Operações Aéreas no Aeródromo Internacional de Belém-PA (Wind Occurrence Frequency Study and Its Importance in Air Operations Security on Belém's International Aerodrome)

2015 ◽  
Vol 7 (6) ◽  
pp. 1110
Author(s):  
Ingrid Monteiro Peixoto de Souza ◽  
Thiago Melo Souza ◽  
José Danilo Costa Souza Filho ◽  
Maria do Carmo Felipe de Oliveira ◽  
Dimitrie Nechet
Keyword(s):  
Air Temperature ◽  
Atmospheric Pressure ◽  
Occurrence Frequency ◽  
Equatorial Atlantic ◽  
Flight Operations ◽  
Equatorial Atlantic Ocean ◽  
Meteorological Observations ◽  
Maximum Temperatures ◽  
Meteorological Elements ◽  
Wind Intensity

Este trabalho teve como objetivo estudar a freqüência de ocorrência de rajada de vento e sua importância na segurança das operações aéreas, uma vez que estas apresentam significativas variações de intensidade do vento, podendo ocasionar, inúmeros riscos para a aviação, desde desconforto durante o voo, até perdas de vidas humanas. Os dados foram obtidos no Aeródromo Internacional de Belém do Pará, no período de 2009 a 2012, onde foram realizadas análises estatísticas, bem como, estudos das correlações dos percentuais de ocorrências com os elementos meteorológicas de superfície (temperatura do ar e pressão atmosférica), extraídas de observações meteorológicas horárias da localidade em estudo. Os resultados mostram, que nos últimos anos, a ocorrência de rajada de vento no aeródromo de Belém-Pa, vem aumentando, onde o maior registro dessa ocorrência dentro do período foi no ano de 2012. A maior frequência de eventos de rajada por intervalos de velocidade foi de 21 a 30 KT. A maior distribuição sazonal do registro de rajadas de vento ocorreu no período mais chuvoso da região, dezembro a maio, influenciadas pela nebulosidade, formada no Oceano Atlântico Equatorial, devido a atuação da ZCIT. As maiores quantidades de registros de rajadas de ventos correspondem ao período de máximas temperaturas, sugerindo uma correlação entre o aquecimento e a ocorrência de rajadas próximas a superfície terrestre. A distribuição de rajada de vento, de acordo com a orientação do vento indica predominância dos ventos de leste, de 60º a 120º.  ABSTRACT This paper aimed to study the wind occurrence frequency and its importance on the safety of flight operations, since these are significant variations in wind intensity, causing many risks to aviation, from discomfort during flight to even loss of lifes. The data were obtained from the International Aerodrome of Belém do Pará, in the period from 2009 to 2012, where statistical analyzes were performed, as well as studies of correlations of the percentage of occurrences with surface meteorological elements (air temperature and atmospheric pressure), extracted from hourly meteorological observations from the study site. The results show that in recent years, the occurrence of gust of wind at the airfield of Belém-Pa, is increasing, where the highest record of this occurrence within the period was in 2012. The higher frequency of events per burst speed intervals was 21-30 KT. The largest seasonal distribution record wind gusts occurred in the rainy season in the region, from December to May, influenced by clouds formed in the Equatorial Atlantic Ocean, due to tripping of the ITCZ​. The largest amounts of records gusty winds correspond to the period of maximum temperatures, suggesting a correlation between warming and the occurrence of near Earth's surface bursts. The distribution of wind, according to the orientation of the wind indicates predominance of winds east 60 º to 120 º.   Keywords: Wind direction, air temperature, atmospheric pressure.  

scholarly journals Leading Modes of the Upper-Ocean Temperature Interannual Variability along the Equatorial Atlantic Ocean in NCEP GODAS

2013 ◽  
Vol 26 (13) ◽  
pp. 4649-4663 ◽  
Author(s):  
Zeng-Zhen Hu ◽  
Arun Kumar ◽  
Bohua Huang ◽  
Jieshun Zhu
Keyword(s):  
Interannual Variability ◽  
Zonal Wind ◽  
Thermocline Depth ◽  
Ocean Temperature ◽  
Equatorial Atlantic ◽  
Equatorial Atlantic Ocean ◽  
Leading Mode ◽  
Equatorial Ocean ◽  
Meridional Mode ◽  
Atlantic Meridional Mode

Abstract In this work, the authors analyze the physical mechanisms of interannual variability of the upper-ocean temperature anomaly (OTA) in the equatorial Atlantic Ocean, using ocean reanalysis from the National Centers for Environmental Prediction (NCEP) Global Ocean Data Assimilation System. The variability of equatorial Atlantic OTA is dominated by two leading modes. The first mode is characterized by same-sign variation along the thermocline with pronounced amplitude in the central and eastern equatorial Atlantic. This mode represents the modulation of the overall thermocline depth at the equator generated by net heat convergence in the equatorial ocean, with heat content first accumulated mainly in the off-equatorial northwestern Atlantic in response to anomalous wind curl associated with Atlantic meridional mode. The second leading mode shows an opposite variation between the western and eastern Atlantic. This mode is mainly driven by the zonal wind stress fluctuation confined in the southwestern tropical and equatorial Atlantic and reflects the equatorial balanced response between the zonal slope of the equatorial thermocline depth and the atmospheric zonal wind variations with pronounced surface wind and ocean anomalies in the southwestern and equatorial ocean. The different characteristics of these two modes suggest that they may occur independently. In fact, evolution of the two leading modes is approximately in quadrature, and they may also occur in sequence on interannual time scales. The two leading mode-associated air–sea interaction processes suggest that the Atlantic meridional mode and zonal mode are statistically and physically connected in their evolution.

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