Can Environmental Conditions at North Atlantic Deep-Sea Habitats Be Predicted Several Years Ahead? ——Taking Sponge Habitats as an Example

Predicting the ambient environmental conditions in the coming several years to one decade is of key relevance for elucidating how deep-sea habitats, like for example sponge habitats, in the North Atlantic will evolve under near-future climate change. However, it is still not well known to what extent the deep-sea environmental properties can be predicted in advance. A regional downscaling prediction system is developed to assess the potential predictability of the North Atlantic deep-sea environmental factors. The large-scale climate variability predicted with the coupled Max Planck Institute Earth System Model with low-resolution configuration (MPI-ESM-LR) is dynamically downscaled to the North Atlantic by providing surface and lateral boundary conditions to the regional coupled physical-ecosystem model HYCOM-ECOSMO. Model results of two physical fields (temperature and salinity) and two biogeochemical fields (concentrations of silicate and oxygen) over 21 sponge habitats are taken as an example to assess the ability of the downscaling system to predict the interannual to decadal variations of the environmental properties based on ensembles of retrospective predictions over the period from 1985 to 2014. The ensemble simulations reveal skillful predictions of the environmental conditions several years in advance with distinct regional differences. In areas closely tied to large-scale climate variability and ice dynamics, both the physical and biogeochemical fields can be skillfully predicted more than 4 years ahead, while in areas under strong influence of upper oceans or open boundaries, the predictive skill for both fields is limited to a maximum of 2 years. The simulations suggest higher predictability for the biogeochemical fields than for the physical fields, which can be partly attributed to the longer persistence of the former fields. Predictability is improved by initialization in areas away from the influence of Mediterranean outflow and areas with weak coupling between the upper and deep oceans. Our study highlights the ability of the downscaling regional system to predict the environmental variations at deep-sea benthic habitats on time scales of management relevance. The downscaling system therefore will be an important part of an integrated approach towards the preservation and sustainable exploitation of the North Atlantic benthic habitats.

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Millennial-scale Holocene climate variability in the NW China drylands and links to the tropical Pacific and the North Atlantic

Palaeogeography Palaeoclimatology Palaeoecology ◽

10.1016/j.palaeo.2005.09.008 ◽

2006 ◽

Vol 233 (1-2) ◽

pp. 149-162 ◽

Cited By ~ 47

Author(s):

Yongtao Yu ◽

Taibao Yang ◽

Jijun Li ◽

Jinfeng Liu ◽

Congrong An ◽

...

Keyword(s):

Climate Variability ◽

North Atlantic ◽

Tropical Pacific ◽

Holocene Climate ◽

Nw China ◽

The North ◽

The North Atlantic ◽

The Tropical Pacific ◽

Millennial Scale

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Seasonal Predictability of Wintertime mid-latitude Cyclonic Activity over the North Atlantic and Europe

10.5194/egusphere-egu21-11134 ◽

2021 ◽

Author(s):

Alvise Aranyossy ◽

Sebastian Brune ◽

Lara Hellmich ◽

Johanna Baehr

Keyword(s):

North Atlantic ◽

Large Scale ◽

Jet Stream ◽

Cyclonic Activity ◽

Max Planck ◽

Pressure System ◽

Wind Speeds ◽

Average Lifespan ◽

The North ◽

The North Atlantic

We analyse the connections between the wintertime North Atlantic Oscillation (NAO), the eddy-driven jet stream with the mid-latitude cyclonic activity over the North Atlantic and Europe. We investigate, through the comparison against ECMWF ERA5 and hindcast simulations from the Max Planck Institute Earth System Model (MPI-ESM), the potential for enhancement of the seasonal prediction skill of the Eddy Kinetic Energy (EKE) by accounting for the connections between large-scale climate and the regional cyclonic activity. Our analysis focuses on the wintertime months (December-March) in the 1979-2019 period, with seasonal predictions initialized every November 1st. We calculate EKE from wind speeds at 250 hPa, which we use as a proxy for cyclonic activity. The zonal and meridional wind speeds are bandpass filtered with a cut-off at 3-10 days to fit with the average lifespan of mid-latitude cyclones.&#160;Preliminary results suggest that in ERA5, major positive anomalies in EKE, both in quantity and duration, are correlated with a northern position of the jet stream and a positive phase of the NAO. Apparently, a deepened Icelandic low-pressure system offers favourable conditions for mid-latitude cyclones in terms of growth and average lifespan. In contrast, negative anomalies in EKE over the North Atlantic and Central Europe are associated with a more equatorward jet stream, these are also linked to a negative phase of the NAO.&#160; Thus, in ERA5, the eddy-driven jet stream and the NAO play a significant role in the spatial and temporal distribution of wintertime mid-latitude cyclonic activity over the North Atlantic and Europe. We extend this connection to the MPI-ESM hindcast simulations and present an analysis of their predictive skill of EKE for wintertime months.

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The North Atlantic Ocean as a Modulator of Vegetation Greening/Browning in the Northern High Latitudes?

10.5194/egusphere-egu21-15595 ◽

2021 ◽

Author(s):

Leonard F. Borchert ◽

Alexander J. Winkler

Keyword(s):

Climate Variability ◽

North Atlantic ◽

North Atlantic Ocean ◽

Internal Variability ◽

Dominant Mode ◽

High Latitudes ◽

Model Simulations ◽

Internal Climate Variability ◽

The North ◽

The North Atlantic

Vegetation in the northern high latitudes shows a characteristic pattern of persistent changes as documented by multi-decadal satellite observations. The prevailing explanation that these mainly increasing trends (greening) are a consequence of external CO2 forcing, i.e., due to the ubiquitous effect of CO2-induced fertilization and/or warming of temperature-limited ecosystems, however does not explain why some areas also show decreasing trends of vegetation cover (browning). We propose here to consider the dominant mode of multi-decadal internal climate variability in the north Atlantic region, the Atlantic Multidecadal Variability (AMV), as the missing link in the explanation of greening and browning trend patterns in the northern high latitudes. Such a link would also imply potential for decadal predictions of ecosystem changes in the northern high latitudes.An analysis of observational and reanalysis data sets for the period 1979-2019 shows that locations characterized by greening trends largely coincide with warming summer temperature and increasing precipitation. Wherever either cooling or decreasing precipitation occurs, browning trends are observed over this period. These precipitation and temperature patterns are significantly correlated with a North Atlantic sea surface temperature index that represents the AMV signal, indicating its role in modulating greening/browning trend patterns in the northern high latitudes.Using two large ensembles of coupled Earth system model simulations (100 members of MPI-ESM-LR Grand Ensemble and 32 members of the IPSL-CM6A-LR Large Ensemble), we separate the greening/browning pattern caused by external CO2 forcing from that caused by internal climate variability associated with the AMV. These sets of model simulations enable a clean separation of the externally forced signal from internal variability. While the greening and browning patterns in the simulations do not agree with observations in terms of magnitude and location, we find consistent internally generated greening/browning patterns in both models caused by changes in temperature and precipitation linked to the AMV signal. These greening/browning trend patterns are of the same magnitude as those caused by the external forcing alone. Our work therefore shows that internally-generated changes of vegetation in the northern lands, driven by AMV, are potentially as large as those caused by external CO2 forcing. We thus argue that the observed pattern of greening/browning in the northern high latitudes could originate from the combined effect of rising CO2 as well as the AMV.

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Bunker Cave stalagmites: an archive for central European Holocene climate variability

Climate of the Past Discussions ◽

10.5194/cpd-8-1687-2012 ◽

2012 ◽

Vol 8 (3) ◽

pp. 1687-1720 ◽

Cited By ~ 9

Author(s):

J. Fohlmeister ◽

A. Schröder-Ritzrau ◽

D. Scholz ◽

C. Spötl ◽

D. F. C. Riechelmann ◽

...

Keyword(s):

Climate Variability ◽

North Atlantic ◽

Little Ice Age ◽

Ice Age ◽

Holocene Climate ◽

Central European ◽

The North ◽

The North Atlantic ◽

Meteoric Precipitation ◽

Precipitation And Temperature

Abstract. Holocene climate was characterised by variability on multi-centennial to multi-decadal time scales. In central Europe, these fluctuations were most pronounced during winter. Here we present a new record of past winter climate variability for the last 10.8 ka based on four speleothems from Bunker Cave, Western Germany. Due to its central European location, the cave site is particularly well suited to record changes in precipitation and temperature in response to changes in the North Atlantic realm. We present high resolution records of δ18O, δ13C values and Mg/Ca ratios. We attribute changes in the Mg/Ca ratio to variations in the meteoric precipitation. The stable C isotope composition of the speleothems most likely reflects changes in vegetation and precipitation and variations in the δ18O signal are interpreted as variations in meteoric precipitation and temperature. We found cold and dry periods between 9 and 7 ka, 6.5 and 5.5 ka, 4 and 3 ka as well as between 0.7 to 0.2 ka. The proxy signals in our stalagmites compare well with other isotope records and, thus, seem representative for central European Holocene climate variability. The prominent 8.2 ka event and the Little Ice Age cold events are both recorded in the Bunker cave record. However, these events show a contrasting relationship between climate and δ18O, which is explained by different causes underlying the two climate anomalies. Whereas the Little Ice Age is attributed to a pronounced negative phase of the North Atlantic Oscillation, the 8.2 ka event was triggered by cooler conditions in the North Atlantic due to a slowdown of the Thermohaline Circulation.

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Climate impacts on multidecadal pCO2 variability in the North Atlantic: 1948–2009

Biogeosciences Discussions ◽

10.5194/bgd-12-15223-2015 ◽

2015 ◽

Vol 12 (17) ◽

pp. 15223-15244

Author(s):

M. L. Breeden ◽

G. A. McKinley

Keyword(s):

North Atlantic ◽

Large Scale ◽

Dissolved Inorganic Carbon ◽

Atlantic Multidecadal Oscillation ◽

Climate Impacts ◽

Co2 Uptake ◽

Subpolar Gyre ◽

The North ◽

The North Atlantic

Abstract. The North Atlantic is the most intense region of ocean CO2 uptake. Here, we investigate multidecadal timescale variability of the partial pressure CO2 (pCO2) that is due to the natural carbon cycle using a regional model forced with realistic climate and pre-industrial atmospheric pCO2 for 1948–2009. Large-scale patterns of natural pCO2 variability are primarily associated with basin-averaged sea surface temperature (SST) that, in turn, is composed of two parts: the Atlantic Multidecadal Oscillation (AMO) and a long-term positive SST trend. The North Atlantic Oscillation (NAO) drives a secondary mode of variability. For the primary mode, positive AMO and the SST trend modify pCO2 with different mechanisms and spatial patterns. Warming with the positive AMO increases subpolar gyre pCO2, but there is also a significant reduction of dissolved inorganic carbon (DIC) due primarily to reduced vertical mixing. The net impact of positive AMO is to reduce pCO2 in the subpolar gyre. Through direct impacts on SST, the net impacts of positive AMO is to increase pCO2 in the subtropical gyre. From 1980 to present, long-term SST warming has amplified AMO impacts on pCO2.

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Lagrangian formation pathways of moist anomalies in the trade-wind region during the dry season: two case studies from EUREC4A

10.5194/wcd-2021-42 ◽

2021 ◽

Author(s):

Leonie Villiger ◽

Heini Wernli ◽

Maxi Boettcher ◽

Martin Hagen ◽

Franziska Aemisegger

Keyword(s):

Long Range ◽

North Atlantic ◽

Large Scale ◽

Cold Front ◽

Trade Wind ◽

Long Range Transport ◽

The North ◽

Range Transport ◽

The North Atlantic ◽

The Tropics

Abstract. Shallow clouds in the trade-wind region over the North Atlantic contribute substantially to the global radiative budget. In the vicinity of the Caribbean island Barbados, they appear in different mesoscale organisation patterns with distinct net cloud radiative effects (CRE). Cloud formation processes in this region are typically controlled by the prevailing large-scale subsidence. However, occasionally weather systems from remote origin cause significant disturbances. This study investigates the complex cloud-circulation interactions during the field campaign EUREC4A (Elucidate the Couplings Between Clouds, Convection and Circulation) from 16 January to 20 February 2020, using a combination of Eulerian and Lagrangian diagnostics. Based on observations and ERA5 reanalyses, we identify the relevant processes and characterise the formation pathways of two moist anomalies above the Barbados Cloud Observatory (BCO), one in the lower (~1000–650 hPa) and one in the middle troposphere (~650–300 hPa). These moist anomalies are associated with strongly negative CRE values and with contrasting long-range transport processes from the extratropics and the tropics, respectively. The low-level moist anomaly is characterised by an unusually thick cloud layer, high precipitation totals and a strongly negative CRE. Its formation is connected to an “extratropical dry intrusion” (EDI) that interacts with a trailing cold front. A quasi-climatological (2010–2020) analysis reveals that EDIs lead to different conditions at the BCO depending on how they interact with the associated cold front. Based on this climatology, we discuss the relevance of the strong large-scale forcing by EDIs for the low-cloud patterns near the BCO and the related CRE. The second case study about the mid-tropospheric moist anomaly is associated with an extended and persistent mixed-phase shelf cloud and the lowest daily CRE value observed during the campaign. Its formation is linked to “tropical mid-level detrainment” (TMD), which refers to detrainment from tropical deep convection near the melting layer. The quasi-climatological analysis shows that TMDs consistently lead to mid-tropospheric moist anomalies over the BCO and that the detrainment height controls the magnitude of the anomaly. However, no systematic relationship was found between the amplitude of this mid-tropospheric moist anomaly and the CRE at the BCO. Overall, this study reveals the important impact of the long-range transport, driven by dynamical processes either in the extratropics or the tropics, on the variability of the vertical structure of moisture and clouds, and on the resulting CRE in the North Atlantic winter trades.

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