scholarly journals The Evaluation of the North Atlantic Climate System in UKESM1 Historical Simulations for CMIP6

2020 ◽  
Vol 12 (9) ◽  
Author(s):  
Jon Robson ◽  
Yevgeny Aksenov ◽  
Thomas J. Bracegirdle ◽  
Oscar Dimdore‐Miles ◽  
Paul T. Griffiths ◽  
...  
Keyword(s):  
North Atlantic ◽  
Climate System ◽  
The North ◽  
North Atlantic Climate ◽  
The North Atlantic

Atmospheric composition changes in CMIP6 experiments over the North Atlantic region

2020 ◽  
Author(s):  
Paul Griffiths ◽  
James Keeble ◽  
Fiona O'Connor ◽  
Alexander Archibald ◽  
John Pyle ◽  
...  
Keyword(s):  
North Atlantic ◽  
Radiative Forcing ◽  
Climate Model ◽  
Climate System ◽  
Atmospheric Composition ◽  
North Atlantic Region ◽  
Atlantic Region ◽  
The North ◽  
North Atlantic Climate ◽  
The North Atlantic

<div> <div> <div> <p>A grand challenge in the field of chemistry-climate modelling is understanding the connection between anthropogenic emissions, atmospheric composition and the radiative forcing of trace gases and aerosols.</p> <p>The 6th phase of the Coupled Model Intercomparison Project (CMIP6) includes a number of climate model experiments that can be used for this purpose.  AerChemMIP [Collins et al.2017] focuses on calculating the radiative forcing of gases and aerosol particles over the period 1850 to 2100, and comprises several tiers of experiments designed to attribute the effect of changes in emissions. </p> <p>The UK Earth System Model, UKESM-1, is a novel climate model developed for CMIP6  [Sellar et al., 2019] and is a community research tool for studying past and future climate.  It includes a detailed treatment of tropospheric chemistry, interactive BVOC emissions and extensive stratospheric chemistry.</p> <p>The North Atlantic Climate System is an area of current interest [Robson et al., 2020] and is the focus of the UKRI 'ACSIS' project.  ACSIS brings together scientists from a range of different specialisms to understand complex changes in the North Atlantic climate system.    By understanding how these changes relate to external drivers of climate, such as human activity, or natural variability, ACSIS aims to improve our capability to detect, explain and predict changes in the North Atlantic climate system.</p> <p>We present an analysis of the evolution of atmospheric composition over the period 1950-2015. The work is based on a recent global multi-model evaluation of tropospheric ozone for CMIP6 [Griffiths et al., 2020] , but focuses on changes over the North Atlantic region in UKESM-1.  We draw on CMIP and AerChemMIP simulations to provide an initial survey of the response of this region to changing emissions , focusing on atmospheric composition and attempting attribution from a series of targeted experiments involving perturbed emissions .</p> </div> </div> </div>

scholarly journals Recent multivariate changes in the North Atlantic climate system, with a focus on 2005-2016

2018 ◽  
Vol 38 (14) ◽  
pp. 5050-5076 ◽  
Author(s):  
Jon Robson ◽  
Rowan T. Sutton ◽  
Alex Archibald ◽  
Fenwick Cooper ◽  
Matthew Christensen ◽  
...  
Keyword(s):  
North Atlantic ◽  
Climate System ◽  
The North ◽  
North Atlantic Climate ◽  
The North Atlantic

Aircraft campaigns in support of the North Atlantic Climate System Integrated Studies (ACSIS)

2020 ◽  
Author(s):  
Alexander Archibald ◽  
Keyword(s):  
North Atlantic ◽  
Repeated Measurements ◽  
Climate System ◽  
Atmospheric Composition ◽  
Sea Ice Thickness ◽  
The North ◽  
Climate Interactions ◽  
North Atlantic Climate ◽  
The North Atlantic

<p>The North Atlantic is witnessing major changes during the Anthropocene. These include changes in the physical climate system: in ocean and atmosphere temperatures and circulation; in sea ice thickness and extent; and in atmospheric composition, where ozone, ozone precursors and aerosols have undergone significant changes over the last few decades. Changes in aerosols over the North Atlantic have been linked to changes in sea surface temperatures (SST) and North Atlantic climate variability. A long-term research project, The North Atlantic Climate System Integrated Study (ACSIS), involving data collection and interpretation, has begun to better understand the processes and composition-climate interactions associated with these changes. Here we report on one of the major observational components of the ACSIS programme which involves repeated measurements of the composition of the North Atlantic using the NERC FAAM BAe146. To date six campaigns have taken place including three which coincided with the NASA ATom campaigns (2-4). </p><p><br>In this presentation we will discuss the rationale for the aircraft project and recent results including the observation of transport of biomass burning plumes into the North Atlantic that are estimated to have originated from fires sampled as part of the NASA FIREX campaigns during the summer of 2019. We will highlight results from an intercomparison with the NASA DC-8 during our second campaign and ATom 3, which reveal good agreement in measurements of O3, CO and NOx between the two aircraft but large differences in measurements of non-methane VOCs, and we will summarise our results to-date including the comparison against chemical transport models. </p><p> </p>

scholarly journals Glacial fluctuations of the Indian monsoon and their relationship with North Atlantic climate: new data and modelling experiments

2013 ◽  
Vol 9 (5) ◽  
pp. 2135-2151 ◽  
Author(s):  
C. Marzin ◽  
N. Kallel ◽  
M. Kageyama ◽  
J.-C. Duplessy ◽  
P. Braconnot
Keyword(s):  
North Atlantic ◽  
Bay Of Bengal ◽  
Indian Monsoon ◽  
Hydrological Cycle ◽  
Atlantic Meridional Overturning Circulation ◽  
Meridional Overturning Circulation ◽  
The North ◽  
North Atlantic Climate ◽  
Meridional Overturning ◽  
The North Atlantic

Abstract. Several paleoclimate records such as from Chinese loess, speleothems or upwelling indicators in marine sediments present large variations of the Asian monsoon system during the last glaciation. Here, we present a new record from the northern Andaman Sea (core MD77-176) which shows the variations of the hydrological cycle of the Bay of Bengal. The high-resolution record of surface water δ18O dominantly reflects salinity changes and displays large millennial-scale oscillations over the period 40 000 to 11 000 yr BP. Their timing and sequence suggests that events of high (resp. low) salinity in the Bay of Bengal, i.e. weak (resp. strong) Indian monsoon, correspond to cold (resp. warm) events in the North Atlantic and Arctic, as documented by the Greenland ice core record. We use the IPSL_CM4 Atmosphere-Ocean coupled General Circulation Model to study the processes that could explain the teleconnection between the Indian monsoon and the North Atlantic climate. We first analyse a numerical experiment in which such a rapid event in the North Atlantic is obtained under glacial conditions by increasing the freshwater flux in the North Atlantic, which results in a reduction of the intensity of the Atlantic meridional overturning circulation. This freshwater hosing results in a weakening of the Indian monsoon rainfall and circulation. The changes in the continental runoff and local hydrological cycle are responsible for an increase in salinity in the Bay of Bengal. This therefore compares favourably with the new sea water δ18O record presented here and the hypothesis of synchronous cold North Atlantic and weak Indian monsoon events. Additional sensitivity experiments are produced with the LMDZ atmospheric model to analyse the teleconnection mechanisms between the North Atlantic and the Indian monsoon. The changes over the tropical Atlantic are shown to be essential in triggering perturbations of the subtropical jet over Africa and Eurasia, that in turn affect the intensity of the Indian monsoon. These relationships are also found to be valid in additional coupled model simulations in which the Atlantic meridional overturning circulation (AMOC) is forced to resume.

scholarly journals The North Atlantic Warming Hole as Part of a Century-Long Fluctuating Phenomenon

2021 ◽  
Author(s):  
Arnold Taylor
Keyword(s):  
Global Warming ◽  
Heat Transport ◽  
Temperature Change ◽  
North Atlantic ◽  
Meridional Circulation ◽  
Ocean Heat Transport ◽  
The North ◽  
Published Evidence ◽  
North Atlantic Climate ◽  
The North Atlantic

Despite global warming, a region of the North Atlantic has been observed to cool, a phenomenon known as theáNorth Atlantic Warming Holeá(NAWH). The causes of the NAWH remain under debate but its emergence has been linked to a slowdown of the meridional circulation leading to a reduced ocean heat transport into the warming hole region. This note uses previously published evidence to suggest that the pattern of temperature change is not unique but may have been a recurring feature during the last century and a half, fluctuating between a positive and negative phase. It appears global warming has amplified one of these phases in the North Atlantic climate.

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