scholarly journals Remote climate forcing of decadal-scale regime shifts in Northwest Atlantic shelf ecosystems

2013 ◽  
Vol 58 (3) ◽  
pp. 803-816 ◽  
Author(s):  
Charles H. Greene ◽  
Erin Meyer-Gutbrod ◽  
Bruce C. Monger ◽  
Louise P. McGarry ◽  
Andrew J. Pershing ◽  
...  
Keyword(s):  
Regime Shifts ◽  
Climate Forcing ◽  
Northwest Atlantic ◽  
Decadal Scale

Annual to decadal-scale variations in northwest Atlantic sector temperatures inferred from Labrador tree rings

1996 ◽  
Vol 26 (1) ◽  
pp. 143-148 ◽  
Author(s):  
Rosanne D. D'arrigo ◽  
Edward R. Cook ◽  
Gordon C. Jacoby
Keyword(s):  
Warm Season ◽  
Temperature Sensitive ◽  
Northwest Atlantic ◽  
Atlantic Sector ◽  
Grand Banks ◽  
Maximum Latewood Density ◽  
Latewood Density ◽  
Scale Temperature ◽  
Decadal Scale ◽  
North Atlantic Climate

Temperature-sensitive maximum latewood density chronologies from sites near tree line in Labrador are used to infer past changes in warm-season surface air and sea surface temperatures for the northwest Atlantic. Temperatures are reconstructed for the Grand Banks region based on density records from southern Labrador, while a density series from near Okak Fiord, northern Labrador, is used to infer past temperature variations for north-coastal Labrador and the adjacent Labrador Sea. The Labrador chronologies show good agreement with annual and decadal-scale temperature fluctuations over the recent period of instrumental record, and extend this temperature information into the past by several centuries. The lowest density value at the Okak site occurs in 1816, known as the "year without a summer" in eastern North America. Spectral analyses reveal statistically significant variations with periods of around 8.7, 18–22, and 45–66 years. These fluctuations are in general agreement with those identified in several instrumental and modeling analyses of North Atlantic climate.

scholarly journals The recruitment of Atlantic salmon in Europe

2009 ◽  
Vol 66 (2) ◽  
pp. 289-304 ◽  
Author(s):  
Kevin D. Friedland ◽  
Julian C. MacLean ◽  
Lars P. Hansen ◽  
Arnaud J. Peyronnet ◽  
Lars Karlsson ◽  
...  
Keyword(s):  
Atlantic Salmon ◽  
North Atlantic ◽  
Atlantic Multidecadal Oscillation ◽  
Climate Forcing ◽  
Biological Interactions ◽  
Physical Forcing ◽  
The North ◽  
Decadal Scale ◽  
The North Atlantic Oscillation ◽  
Growth Analyses

Abstract Friedland, K. D., MacLean, J. C., Hansen, L. P., Peyronnet, A. J., Karlsson, L., Reddin, D. G., Ó Maoiléidigh, N., and McCarthy, J. L. 2009. The recruitment of Atlantic salmon in Europe. – ICES Journal of Marine Science, 66: 289–304. The stock complex of Atlantic salmon, Salmo salar, in Europe has experienced a multidecadal decline in recruitment, resulting in the lowest stock abundances observed since 1970. Here, physical forcing, biological interactions, and the resultant growth response of post-smolt salmon are examined with a view to understanding the mechanism controlling recruitment. Sea surface temperature (SST) has increased in the Northeast Atlantic, with the pattern and seasonal change in SST negatively correlated with post-smolt survival during summer and in a region that spatially matches the post-smolt nursery. Constituents of the pelagic foodweb, including potential post-smolt food and plankton that may affect post-smolt forage, have changed on a decadal scale and correlate with salmon survival. Retrospective growth analyses of eight stock/sea age components show that post-smolt growth during summer is positively correlated with salmon survival and recruitment. The Atlantic Multidecadal Oscillation appears to be a more closely aligned climate forcing index than the North Atlantic Oscillation with respect to salmon recruitment. European Atlantic salmon recruitment appears to be governed by factors that affect the growth of post-smolts during their first summer at sea, including SST and forage abundances; growth appears to mediate survival by the functional relationship between post-smolts and their predators.

scholarly journals Simulated high-latitude soil thermal dynamics during the past four decades

2015 ◽  
Vol 9 (2) ◽  
pp. 2301-2337 ◽  
Author(s):  
S. Peng ◽  
P. Ciais ◽  
G. Krinner ◽  
T. Wang ◽  
I. Gouttevin ◽  
...  
Keyword(s):  
Active Layer ◽  
Loss Rate ◽  
Rate Of Change ◽  
Climate Forcing ◽  
Active Layer Thickness ◽  
Thermal Dynamics ◽  
Near Surface ◽  
Key Indicator ◽  
Decadal Scale ◽  
Downward Radiation

Abstract. Soil temperature (Ts) change is a key indicator of the dynamics of permafrost. On seasonal and inter-annual time scales, the variability of Ts determines the active layer depth, which regulates hydrological soil properties and biogeochemical processes. On the multi-decadal scale, increasing Ts not only drives permafrost thaw/retreat, but can also trigger and accelerate the decomposition of soil organic carbon. The magnitude of permafrost carbon feedbacks is thus closely linked to the rate of change of soil thermal regimes. In this study, we used nine process-based ecosystem models with permafrost processes, all forced by different observation-based climate forcing during the period 1960–2000, to characterize the warming rate of Ts in permafrost regions. There is a large spread of Ts trends at 20 cm depth across the models, with trend values ranging from 0.010 ± 0.003 to 0.031 ± 0.005 °C yr−1. Most models show smaller increase in Ts with increasing depth. Air temperature (Ta) and longwave downward radiation (LWDR) are the main drivers of Ts trends, but their relative contributions differ amongst the models. Different trends of LWDR used in the forcing of models can explain 61% of their differences in Ts trends, while trends of Ta only explain 5% of the differences in Ts trends. Uncertain climate forcing contributes a larger uncertainty in Ts trends (0.021 ± 0.008 °C yr−1, mean ± SD) than the uncertainty of model structure (0.012 ± 0.001 °C yr−1), diagnosed from the range of response between different models, normalized to the same forcing. In addition, the loss rate of near-surface permafrost area, defined as total area where the maximum seasonal active layer thickness (ALT) is less than 3 m loss rate is found to be significantly correlated with the magnitude of the trends of Ts at 1 m depth across the models (R = −0.85, P = 0.003), but not with the initial total near-surface permafrost area (R = −0.30, P = 0.438). The sensitivity of the total boreal near-surface permafrost area to Ts at 1 m, is estimated to be of −2.80 ± 0.67 million km2 °C−1. Finally, by using two long-term LWDR datasets and relationships between trends of LWDR and Ts across models, we infer an observation-constrained total boreal near-surface permafrost area decrease comprised between 39 ± 14 × 103 and 75 ± 14 × 103 km2 yr−1 from 1960 to 2000. This corresponds to 9–18% degradation of the current permafrost area.

scholarly journals Simulated high-latitude soil thermal dynamics during the past 4 decades

2016 ◽  
Vol 10 (1) ◽  
pp. 179-192 ◽  
Author(s):  
S. Peng ◽  
P. Ciais ◽  
G. Krinner ◽  
T. Wang ◽  
I. Gouttevin ◽  
...  
Keyword(s):  
Active Layer ◽  
Loss Rate ◽  
Rate Of Change ◽  
Climate Forcing ◽  
Active Layer Thickness ◽  
Data Sets ◽  
Thermal Dynamics ◽  
Near Surface ◽  
Decadal Scale ◽  
Downward Radiation

Abstract. Soil temperature (Ts) change is a key indicator of the dynamics of permafrost. On seasonal and interannual timescales, the variability of Ts determines the active-layer depth, which regulates hydrological soil properties and biogeochemical processes. On the multi-decadal scale, increasing Ts not only drives permafrost thaw/retreat but can also trigger and accelerate the decomposition of soil organic carbon. The magnitude of permafrost carbon feedbacks is thus closely linked to the rate of change of soil thermal regimes. In this study, we used nine process-based ecosystem models with permafrost processes, all forced by different observation-based climate forcing during the period 1960–2000, to characterize the warming rate of Ts in permafrost regions. There is a large spread of Ts trends at 20 cm depth across the models, with trend values ranging from 0.010 ± 0.003 to 0.031 ± 0.005 °C yr−1. Most models show smaller increase in Ts with increasing depth. Air temperature (Tsub>a) and longwave downward radiation (LWDR) are the main drivers of Ts trends, but their relative contributions differ amongst the models. Different trends of LWDR used in the forcing of models can explain 61 % of their differences in Ts trends, while trends of Ta only explain 5 % of the differences in Ts trends. Uncertain climate forcing contributes a larger uncertainty in Ts trends (0.021 ± 0.008 °C yr−1, mean ± standard deviation) than the uncertainty of model structure (0.012 ± 0.001 °C yr−1), diagnosed from the range of response between different models, normalized to the same forcing. In addition, the loss rate of near-surface permafrost area, defined as total area where the maximum seasonal active-layer thickness (ALT) is less than 3 m loss rate, is found to be significantly correlated with the magnitude of the trends of Ts at 1 m depth across the models (R = −0.85, P = 0.003), but not with the initial total near-surface permafrost area (R = −0.30, P = 0.438). The sensitivity of the total boreal near-surface permafrost area to Ts at 1 m is estimated to be of −2.80 ± 0.67 million km2 °C−1. Finally, by using two long-term LWDR data sets and relationships between trends of LWDR and Ts across models, we infer an observation-constrained total boreal near-surface permafrost area decrease comprising between 39 ± 14  ×  103 and 75 ± 14  ×  103 km2 yr−1 from 1960 to 2000. This corresponds to 9–18 % degradation of the current permafrost area.

scholarly journals Aerosol direct radiative effects over the northwest Atlantic, northwest Pacific, and North Indian Oceans: estimates based on in-situ chemical and optical measurements and chemical transport modeling

2006 ◽  
Vol 6 (6) ◽  
pp. 1657-1732 ◽  
Author(s):  
T. S. Bates ◽  
T. L. Anderson ◽  
T. Baynard ◽  
T. Bond ◽  
O. Boucher ◽  
...  
Keyword(s):  
Climate Change ◽  
Radiative Transfer ◽  
Chemical Transport ◽  
Climate Forcing ◽  
Northwest Pacific ◽  
Anthropogenic Aerosols ◽  
Northwest Atlantic ◽  
Clear Sky ◽  
Aerosol Properties

Abstract. The largest uncertainty in the radiative forcing of climate change over the industrial era is that due to aerosols, a substantial fraction of which is the uncertainty associated with scattering and absorption of shortwave (solar) radiation by anthropogenic aerosols in cloud-free conditions (IPCC, 2001). Quantifying and reducing the uncertainty in aerosol influences on climate is critical to understanding climate change over the industrial period and to improving predictions of future climate change for assumed emission scenarios. Measurements of aerosol properties during major field campaigns in several regions of the globe during the past decade are contributing to an enhanced understanding of atmospheric aerosols and their effects on light scattering and climate. The present study, which focuses on three regions downwind of major urban/population centers (North Indian Ocean (NIO) during INDOEX, the Northwest Pacific Ocean (NWP) during ACE-Asia, and the Northwest Atlantic Ocean (NWA) during ICARTT), incorporates understanding gained from field observations of aerosol distributions and properties into calculations of perturbations in radiative fluxes due to these aerosols. This study evaluates the current state of observations and of two chemical transport models (STEM and MOZART). Measurements of burdens, extinction optical depth (AOD), and direct radiative effect of aerosols (DRE – change in radiative flux due to total aerosols) are used as measurement-model check points to assess uncertainties. In-situ measured and remotely sensed aerosol properties for each region (mixing state, mass scattering efficiency, single scattering albedo, and angular scattering properties and their dependences on relative humidity) are used as input parameters to two radiative transfer models (GFDL and University of Michigan) to constrain estimates of aerosol radiative effects, with uncertainties in each step propagated through the analysis. Constraining the radiative transfer calculations by observational inputs increases the clear-sky, 24-h averaged AOD (34±8%), top of atmosphere (TOA) DRE (32±12%), and TOA direct climate forcing of aerosols (DCF – change in radiative flux due to anthropogenic aerosols) (37±7%) relative to values obtained with "a priori" parameterizations of aerosol loadings and properties (GFDL RTM). The resulting constrained clear-sky TOA DCF is −3.3±0.47, −14±2.6, −6.4±2.1 Wm−2 for the NIO, NWP, and NWA, respectively. With the use of constrained quantities (extensive and intensive parameters) the calculated uncertainty in DCF was 25% less than the "structural uncertainties" used in the IPCC-2001 global estimates of direct aerosol climate forcing. Such comparisons with observations and resultant reductions in uncertainties are essential for improving and developing confidence in climate model calculations incorporating aerosol forcing.

scholarly journals Historical versus Contemporary Climate Forcing on the Annual Nesting Variability of Loggerhead Sea Turtles in the Northwest Atlantic Ocean

PLoS ONE ◽  
2013 ◽  
Vol 8 (12) ◽  
pp. e81097 ◽  
Author(s):  
Michael D. Arendt ◽  
Jeffrey A. Schwenter ◽  
Blair E. Witherington ◽  
Anne B. Meylan ◽  
Vincent S. Saba
Keyword(s):  
Atlantic Ocean ◽  
Sea Turtles ◽  
Climate Forcing ◽  
Loggerhead Sea Turtles ◽  
Northwest Atlantic ◽  
Contemporary Climate

scholarly journals Tropical–North Pacific Climate Linkages over the Past Four Centuries*

2005 ◽  
Vol 18 (24) ◽  
pp. 5253-5265 ◽  
Author(s):  
Rosanne D’Arrigo ◽  
Rob Wilson ◽  
Clara Deser ◽  
Gregory Wiles ◽  
Edward Cook ◽  
...  
Keyword(s):  
Twentieth Century ◽  
Tree Ring ◽  
North Pacific ◽  
Climatic Variability ◽  
Regime Shifts ◽  
Climate Index ◽  
Climate Indices ◽  
Supporting Evidence ◽  
The Past ◽  
Decadal Scale

Abstract Analyses of instrumental data demonstrate robust linkages between decadal-scale North Pacific and tropical Indo-Pacific climatic variability. These linkages encompass common regime shifts, including the noteworthy 1976 transition in Pacific climate. However, information on Pacific decadal variability and the tropical high-latitude climate connection is limited prior to the twentieth century. Herein tree-ring analysis is employed to extend the understanding of North Pacific climatic variability and related tropical linkages over the past four centuries. To this end, a tree-ring reconstruction of the December–May North Pacific index (NPI)—an index of the atmospheric circulation related to the Aleutian low pressure cell—is presented (1600–1983). The NPI reconstruction shows evidence for the three regime shifts seen in the instrumental NPI data, and for seven events in prior centuries. It correlates significantly with both instrumental tropical climate indices and a coral-based reconstruction of an optimal tropical Indo-Pacific climate index, supporting evidence for a tropical–North Pacific link extending as far west as the western Indian Ocean. The coral-based reconstruction (1781–1993) shows the twentieth-century regime shifts evident in the instrumental NPI and instrumental tropical Indo-Pacific climate index, and three previous shifts. Changes in the strength of correlation between the reconstructions over time, and the different identified shifts in both series prior to the twentieth century, suggest a varying tropical influence on North Pacific climate, with greater influence in the twentieth century. One likely mechanism is the low-frequency variability of the El Niño–Southern Oscillation (ENSO) and its varying impact on Indo-Pacific climate.

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