Meridional Heat Transfer Research Articles

Comments on J. J. Smulsky’s Paper “A New Theory of the Earth Insolation Change over Millions of Years against Marine Isotope Stages”

Insolation calculations for solving the two-body problem have been analyzed. The errors associated with the simplification of the calculation algorithm of insolation and disregard (simultaneously) of the attraction of planets of the solar system and their satellites in calculations of the Earth’s irradiation have been indicated. The use of the method of equivalent latitudes in paleoclimatology has been shown to be inconsistent. The need to take into account changes in the meridional insolation gradient, which regulates the meridional heat transfer from the equator to polar regions, in paleoclimatology and paleogeography has been substantiated.

МАЛЫЙ (СРЕДНЕВЕКОВЫЙ) КЛИМАТИЧЕСКИЙ ОПТИМУМ ГОЛОЦЕНА И ЕГО ВОЗМОЖНЫЕ ПРИЧИНЫ

A brief overview of reliably established global climate events in the Holocene is provided. On the basis of high-precision astronomical ephemeris with high spatial and temporal resolution, the annual and seasonal insolation of the Earth and hemispheres was calculated for the period 3000 BC-AD 2999. According to the results of calculations, the values of insolation contrast were obtained in a generalized manner (for the regions of the heat source and sink), reflecting the changes in the meridional insolation gradient that controls the meridional heat transfer in the hemispheres. The character of long-term variations of both the annual and seasonal arrival, and the annual and seasonal meridional transport of radiation heat in the hemispheres was obtained. The long-term distribution of insolation characteristics of the Earth and hemispheres (annual and seasonal insolation and insolation contrast in the hemispheres) is analyzed. The synchronicity of the extrema of the irradiation characteristics with the global climatic event in the history of the Earth (the Medieval Warm Period of the Holocene) was revealed. On the basis of the revealed synchronicity, the maximum insolation contrast in the winter half of the year in the Northern Hemisphere (the maximum of meridional heat transfer in the winter half of the year), as well as the maximum of interhemispheric heat transfer may be determined to be the reasons for the Medieval Warm Period.

Analysis of satellite data on dynamics of the extent of sea ice due to insolation contrast

On the basis of theoretical calculations of insolation and Earth remote sensing data on the dynamics of the sea ice area in the Arctic Ocean, a close relationship between long-term changes in the sea ice area and annual insolation contrast in the Northern hemisphere was determined. The change in insolation contrast was generalized (in terms of the source and sink of heat) reflects the change in the meridional insolation gradient that regulates the meridional heat transfer in the ocean - atmosphere system. The regression model was used to make an estimated forecast of changes in the area of sea ice in the Arctic Ocean. According to our estimates, the reduction of the average annual sea ice extent in the Arctic Ocean in 2050 will be 18.3% relative to 2018. The Maximum area (March) will be reduced by 10.1%, and the Minimum area (September) by 60.3%. The decrease in the area of sea ice is associated with an increase in the meridional gradient of insolation and meridional heat transfer resulting from a decrease in the inclination of the Earth's rotation axis in the present epoch.

The Problem of Meridional Heat Transport in the Astronomical Climate Theory

The reduction of solar radiation arriving in the summer half of the years by 65° N has been found to be a consequence of decreased inclination of the rotation axis and increased meridional contrast in insolation, rather than a result of climate cooling. Thus, the astronomical climate theory involves a paradox related to the fact that the change in the meridional heat transfer due to a change in the inclination of the rotation axis is disregarded. In this context, the mechanism of the astronomical chronology of climatic events in the Pleistocene needs to be revised.

Ocean-atmosphere climate shift during the mid-to-late Holocene transition

Climate records of the mid-to-late Holocene transition, between 3–4 thousand years before present (ka), often exhibit a rapid change in response to the gradual change in orbital insolation. Here we investigate North Atlantic Central Water circulation as a possible mechanism regulating the latitudinal temperature gradient (LTG), which, in turn, amplifies climate sensitivity to small changes in solar irradiance. Through this mechanism, sharp climate events and transitions are the result of a positive feedback process that propagates and amplifies climate events in the North Atlantic region. We explore these linkages using an intermediate water temperature record reconstructed from Mg/Ca measurements of benthic foraminifera (Hyalinea balthica) from a sediment core off NW Africa (889 m depth) between 0 to 5.5 ka. Our results show that Eastern North Atlantic Central Waters (ENACW) cooled by ∼1°±0.7 °C and densities decreased by σθ=0.4±0.2 between 3.3 and 2.6 ka. This shift in ENACW hydrography illustrates a transition towards enhanced mid-latitude atmospheric circulation after 2.7 ka in particular during cold events of the late-Holocene. The presented records demonstrate the important role of ENACW circulation in propagating the climate signatures of the LTG by reducing the meridional heat transfer from high to low latitudes during the transition from the Holocene Thermal Maximum to the late-Holocene. In addition, the dynamic response of ENACW circulation to the gradual climate forcing of LTGs provides a prime example of an amplifying climate feedback mechanism.

Formation of “Southern Component Water” in the Late Cretaceous: Evidence from Nd-isotopes

Research Article| October 01, 2010 Formation of “Southern Component Water” in the Late Cretaceous: Evidence from Nd-isotopes Stuart A. Robinson; Stuart A. Robinson * 1Department of Earth Sciences, University College London, Gower Street, London WC1E 6BT, UK *E-mail: stuart.robinson@ucl.ac.uk. Search for other works by this author on: GSW Google Scholar Daniel P. Murphy; Daniel P. Murphy 2Department of Oceanography, Texas A&M University, College Station, Texas 77843, USA Search for other works by this author on: GSW Google Scholar Derek Vance; Derek Vance 3Bristol Isotope Group, Department of Earth Sciences, University of Bristol, Wills Memorial Building, Bristol BS8 1RJ, UK Search for other works by this author on: GSW Google Scholar Deborah J. Thomas Deborah J. Thomas 2Department of Oceanography, Texas A&M University, College Station, Texas 77843, USA Search for other works by this author on: GSW Google Scholar Geology (2010) 38 (10): 871–874. https://doi.org/10.1130/G31165.1 Article history received: 01 Mar 2010 rev-recd: 05 May 2010 accepted: 06 May 2010 first online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Stuart A. Robinson, Daniel P. Murphy, Derek Vance, Deborah J. Thomas; Formation of “Southern Component Water” in the Late Cretaceous: Evidence from Nd-isotopes. Geology 2010;; 38 (10): 871–874. doi: https://doi.org/10.1130/G31165.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Constraining deep-ocean circulation during past greenhouse climatic periods, such as the Cretaceous, is important for understanding meridional heat transfer processes, controls on ocean anoxia, and the relative roles of climate and tectonics in determining paleocirculation patterns. Ocean circulation models for the Late Cretaceous and early Paleogene suggest that significant deep-water production occurred in the Southern Ocean, but cannot constrain when this process commenced or what the temporal relationship was between opening tectonic gateways and Late Cretaceous climatic cooling. Nd-isotope data obtained from biogenic apatite (fish teeth and bones) are presented from lower bathyal and abyssal sites in the South Atlantic and Indian Oceans. During the mid-Cretaceous, relatively radiogenic Nd-isotope values suggest that deep-water circulation in these basins was sluggish with inputs likely dominated by seawater-particle exchange processes and, possibly, easily weathered volcanic terranes. In the Campanian–Maastrichtian the Nd-isotopic composition of proto-Indian and South Atlantic deep waters became less radiogenic, suggesting the onset of deep-water formation in the Southern Ocean (Southern Component Water, SCW), consistent with Paleogene reconstructions and ocean circulation models. A combination of Southern Hemisphere cooling and the opening of tectonic gateways during the Campanian likely drove the onset of SCW. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Estimates of Geostrophic Surface Currents in the South Atlantic Bight

The determination of long-term trends in the behavior of the Gulf Stream is critical to understanding the meridional heat transfer cycle and associated global climate change. In this study, in situ current measurements from cross-stream transects of an Acoustic Doppler Current Profiler (ADCP) were used in conjunction with satellite altimetry data to obtain accurate estimates of Gulf Stream surface geostrophic current within the South Atlantic Bight (SAB) between 1992 and 2004. Analysis of time series data reveals that the magnitude of the geostrophic flow varies seasonally and that the seasonally averaged velocity was greatest following the intense 1997–1998 El Niño. Because of the relatively small fluctuations in the Gulf Stream's path, our analysis provides a method for accurate, long-term measurements of Gulf Stream currents for this region of the SAB.

Fronts, water masses and heat content variability in the Western Indian sector of the Southern Ocean during austral summer 2004

High density CTD and XBT sections were covered from 35° to 56°S along 45°E and 57°30′E to investigate the morphology of the main fronts in the southwest Indian Ocean, as a part of the Indian pilot expedition to the Southern Ocean on board ORV Sagar Kanya. Northern branch of the Subtropical Front (NSTF) was observed at ∼ 35°30′S along 45°E. Along 57°30′E, the signature of the Agulhas Return Front (ARF) + Subtropical Front (STF) was identified with a rapid decrease in surface temperature between 43°30′ and 45°S and it is located with a southward shift compared to that at 45°E. The Subantarctic Front (SAF) was distinguished as two fronts as northern SAF (SAF1) and southern SAF (SAF2) along both the meridional sections. Polar Front1 (PF1) was identified between 49° and 50°S whereas Polar Front2 (PF2) was identified between 52° and 54°S along 45°E. This study reveals a southward shift of the oceanic fronts (ARF + STF) from west to east, with a maximum southward displacement of > 2° latitude at 57°30′E. A novel finding of this study is that along 45°E, SAF1 merged with ARF and SSTF and SAF2 ∼ 4° latitude southwards from the merged fronts whereas along 57°30′E, SAF1 was not identified as a merged front with ARF and STF as opposed to earlier studies [Belkin, I.M., Gordon, A.L., 1996. Southern Ocean fronts from the Greenwich Meridian to Tasmania. Journal of Geophysical Research 101, 3675–3696]. The thermocline region was absent south of PF. An enhancement in the mixed layer thickness from 42° to 52°S occurred in association with the strengthening of the wind forcing. Major water masses like Subtropical Surface Water, Subantarctic Surface Water, Mode Water, Antarctic Intermediate Water, Circumpolar Deep Water and Antarctic Bottom Water were identified along 45°E. Upper-ocean heat-content computation revealed a remarkable drop of 989 × 10 7 J m −2 at ∼ 42°S and 1405 × 10 7 J m −2 at ∼ 44°S along 45° and 57°30′E, respectively. We believe that this sudden drop in heat content affects the meridional heat transfer which is crucial to the regional climatic variability.

A coastal upwelling seesaw in the Atlantic Ocean as a result of the closure of the Central American Seaway

Based on coupled climate model experiments, we suggest an antiphase relationship between the two major coastal upwelling zones in the Atlantic Ocean off northwestern and southwestern Africa. We describe this as an ‘upwelling seesaw’. The state of the coastal upwelling seesaw is controlled by variations in the oceanic meridional heat transfer between South and North Atlantic. In particular, we suggest that the Pliocene closure of the Central American Seaway induced a large‐scale redistribution of heat in the Atlantic Ocean, leading to an intensification (weakening) of upwelling off southwest (northwest) Africa.

Analysis of model calibration results: Atlantic Ocean climatic calculations

Calibration of models for calculation of ocean's climatic characteristics, based on the complete system of equations of thermohydrodynamics (3DPEM), was performed. The grid step is 1 °, the number of levels is 18, the testing area is 15,5 S to 79,5 N of the Atlantic Ocean. Wind fields and noisy initial fields of temperature and salinity were specified. Diagnostic calculations and initialization were carried out. From 4 models, which “reached the finish”, 2 were admitted to be the best. The analysis has showed that good characteristics for evaluation of the models are the meridional heat transfer and the field of vertical currents. We think that the inaccuracy determinating the Gulf Stream separation location should be explained by the difficulty of modeling interconnected large-scale processes of the baroclinic ocean with variable bottom relief, but not by the problems of the boundary layer physics.

Numerical modelling of the seasonal variability of the North and Tropical Atlantic currents using an adaptation approach

The paper reports computed data on the seasonal variability of the Atlantic Ocean currents which were obtained through numerical integration (using conservative difference schemes) of non-linear equations of hydrothermodynamics taking into account an upper quasi-homogeneous layer and the bottom topography. The seasonal variability of the meridional heat transfer is discussed. The results were obtained using an adaptation approach.

Determination of the Heat-Transport Coefficient in Energy-Balance Climate Models by Extremization of Entropy Production

Abstract Entropy production has been calculated as a function of the coefficient of meridional heat transfer for two seasonal energy-balance climate models. Both models display extrema in entropy production at values of the coefficient appropriate to the present climate. Inclusion of time dependence in the models is found to be the essential feature for successful application of entropy extremization.

Ice concentrations in the southwest part of the Kara Sea and meridional heat transfer in the atmosphere : Shishkov Yu.A. 1961. (In Russian). Translation: Problemy Severa, (4): 131–137. Problems of the North, (1962) (4): 133–139

Ice concentrations in the southwest part of the Kara Sea and meridional heat transfer in the atmosphere : Shishkov Yu.A. 1961. (In Russian). Translation: Problemy Severa, (4): 131–137. Problems of the North, (1962) (4): 133–139