Milankovitch forcing and meridional moisture flux in the atmosphere : insight from a zonally averaged ocean–atmosphere model

Author Posting. © American Meteorological Society, 2010. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Climate 23 (2010): 4841–4855, doi:10.1175/2010JCLI3273.1.A 1-Myr-long time-dependent solution of a zonally averaged ocean–atmosphere model subject to Milankovitch forcing is examined to gain insight into long-term changes in the planetary-scale meridional moisture flux in the atmosphere. The model components are a one-dimensional (latitudinal) atmospheric energy balance model with an active hydrological cycle and an ocean circulation model representing four basins (Atlantic, Indian, Pacific, and Southern Oceans). This study finds that the inclusion of an active hydrological cycle does not significantly modify the responses of annual-mean air and ocean temperatures to Milankovitch forcing found in previous integrations with a fixed hydrological cycle. Likewise, the meridional overturning circulation of the North Atlantic Ocean is not significantly affected by hydrological changes. Rather, it mainly responds to precessionally driven variations of ocean temperature in subsurface layers (between 70- and 500-m depth) of this basin. On the other hand, annual and zonal means of evaporation rate and meridional flux of moisture in the atmosphere respond notably to obliquity-driven changes in the meridional gradient of annual-mean insolation. Thus, when obliquity is decreased (increased), the meridional moisture flux in the atmosphere is intensified (weakened). This hydrological response is consistent with deuterium excess records from polar ice cores, which are characterized by dominant obliquity cycles.A. A. thanks the Global Environmental and Climate Change Centre of McGill University for a Network Grant that made possible an enriching twoweek stay at WHOI during June 2007. O. M. acknowledges support from theU.S.National Science Foundation. Support from a Canadian NSERC Discovery Grant awarded to L.A.M. is gratefully acknowledged

Time-dependent response of a zonally averaged ocean–atmosphere–sea ice model to Milankovitch forcing

Author Posting. © The Author(s), 2010. This is the author's version of the work. It is posted here by permission of Springer-Verlag for personal use, not for redistribution. The definitive version was published in Climate Dynamics 6 (2010): 763-779, doi:10.1007/s00382-010-0790-6.An ocean-atmosphere-sea ice model is developed to explore the time-dependent response of climate to Milankovitch forcing for the time interval 5-3 Myr BP. The ocean component is a zonally averaged model of the circulation in five basins (Arctic, Atlantic, Indian, Pacific, and Southern Oceans). The atmospheric component is a one-dimensional (latitudinal) energy balance model, and the sea-ice component is a thermodynamic model. Two numerical experiments are conducted. The first experiment does not include sea ice and the Arctic Ocean; the second experiment does. Results from the two experiments are used to investigate (i) the response of annual mean surface air and ocean temperatures to Milankovitch forcing, and (ii) the role of sea ice in this response. In both experiments, the response of air temperature is dominated by obliquity cycles at most latitudes. On the other hand, the response of ocean temperature varies with latitude and depth. Deep water formed between 45°N-65°N in the Atlantic Ocean mainly responds to precession. In contrast, deep water formed south of 60°S responds to obliquity when sea ice is not included. Sea ice acts as a time-integrator of summer insolation changes such that annual mean sea-ice conditions mainly respond to obliquity. Thus, in the presence of sea ice, air temperature changes over the sea ice are amplified, and temperature changes in deep water of southern origin are suppressed since water below sea ice is kept near the freezing point.This work was supported by an NSERC Discovery Grant awarded to L.A.M. We also thank GEC3 for a Network Grant

Paraná River monthly hydrometric data from Rosario City, Argentina: 1875 to 2017

Here we provide the data set obtained as described in detail in Antico et al. (2018, doi:10.1002/2017WR020897); a brief description is presented below. We imaged and digitized paper format official national data of daily Paraná water level observations taken at Rosario City, Argentina, from January 1875 to July 2017. Quality checks were applied to the digitized official daily levels in order to flag suspicious values. A corrected version of the official level data was obtained by eliminating the errors caused by gauge sinkings that may have occurred from 1875 to 1908. A rating curve was obtained for Rosario and it was used to convert official and corrected levels into official and corrected discharges, respectively. The water level and discharge data provided here constitute the longest (last 143 years) continuous hydrometric records of the Paraná River, one of the ten largest rivers in the world

Paraná River daily hydrometric data from Rosario City, Argentina: 1875 to 2017

Here we provide the data set obtained as described in detail in Antico et al. (2018, doi:10.1002/2017WR020897); a brief description is presented below. We imaged and digitized paper format official national data of daily Paraná water level observations taken at Rosario City, Argentina, from January 1875 to July 2017. Quality checks were applied to the digitized official daily levels in order to flag suspicious values. A corrected version of the official level data was obtained by eliminating the errors caused by gauge sinkings that may have occurred from 1875 to 1908. A rating curve was obtained for Rosario and it was used to convert official and corrected levels into official and corrected discharges, respectively. The water level and discharge data provided here constitute the longest (last 143 years) continuous hydrometric records of the Paraná River, one of the ten largest rivers in the world

Improved Paraná River hydrometric data from 1875 to 1883

Paraná River hydrometric data from 1875 to 1883 were previously published in the Pangaea database (https://doi.org/10.1594/PANGAEA.882613). Recently, we obtained similar but more accurate data, which are briefly described below (see details in Antico et al. 2020). We imaged and digitized typewritten data of daily Paraná water levels observed at Rosario City, Argentina, from January 1875 to December 1883. Since these data were published by the Argentinian government, they are referred here as “official” data. Quality checks were applied to the official water levels in order to flag suspicious values. A corrected version of the official level data was obtained by correcting errors caused by a gauge sinking. A rating curve was used to convert official and corrected levels into official and corrected discharges, respectively. Water level and discharge data are available here as daily values and monthly means. To obtain monthly means, we used only the daily values that passed all the quality checks