| 1. |
- Dunn, R. J. H., et al.
(författare)
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GLOBAL CLIMATE : State of the Climate in 2020
- 2021
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Ingår i: Bulletin of the American Meteorological Society. - : American Meteorological Society. - 0003-0007 .- 1520-0477. ; 102:8
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Tidskriftsartikel (refereegranskat)
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| 2. |
- Kaiqiang, Deng, et al.
(författare)
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Global Near-Surface Wind Speed Changes over the Last Decades Revealed by Reanalyses and CMIP6 Model Simulations
- 2021
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Ingår i: Journal of Climate. - 0894-8755 .- 1520-0442. ; 34:6, s. 2219-2234
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Tidskriftsartikel (refereegranskat)abstract
- Near-surface (10 m) wind speed (NWS) plays a crucial role in many areas, including hydrological cycles, wind energy production, and air pollution, but what drives its multidecadal changes is still unclear. Using reanalysis datasets and model simulations from phase 6 of the Coupled Model Intercomparison Projection (CMIP6), this study investigates recent trends in the annual mean NWS. The results show that the Northern Hemisphere (NH) terrestrial NWS experienced significant (p < 0.1) decreasing trends during 1980–2010, when the Southern Hemisphere (SH) ocean NWS was characterized by significant (p < 0.1) upward trends. However, during 2010–19, global NWS trends shifted in their sign: NWS trends over the NH land became positive, and trends over the SH tended to be negative. We propose that the strengthening of SH NWS during 1980–2010 was associated with an intensified Hadley cell over the SH, while the declining of NH land NWS could have been caused by changes in atmospheric circulation, alteration of vegetation and/or land use, and the accelerating Arctic warming. The CMIP6 model simulations further demonstrate that the greenhouse gas (GHG) warming plays an important role in triggering the NWS trends over the two hemispheres during 1980–2010 through modulating meridional atmospheric circulation. This study also points at the importance of anthropogenic GHG forcing and the natural Pacific decadal oscillation to the long-term trends and multidecadal variability in global NWS, respectively.
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| 3. |
- Zha, J. L., et al.
(författare)
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Projected changes in global terrestrial near-surface wind speed in 1.5 degrees C-4.0 degrees C global warming levels
- 2021
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Ingår i: Environmental Research Letters. - : IOP Publishing. - 1748-9326. ; 16:11
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Tidskriftsartikel (refereegranskat)abstract
- Understanding future changes in global terrestrial near-surface wind speed (NSWS) in specific global warming level (GWL) is crucial for climate change adaption. Previous studies have projected the NSWS changes; however, the changes of NSWS with different GWLs have yet to be studied. In this paper, we employ the Max Planck Institute Earth System Model large ensembles to evaluate the contributions of different GWLs to the NSWS changes. The results show that the NSWS decreases over the Northern Hemisphere (NH) mid-to-high latitudes and increases over the Southern Hemisphere (SH) as the GWL increases by 1.5 degrees C-4.0 degrees C relative to the preindustrial period, and that these characteristics are more significant with the stronger GWL. The probability density of the NSWS shifts toward weak winds over NH and strong winds over SH between the current climate and the 4.0 degrees C GWL. Compared to 1.5 degrees C GWL, the NSWS decreases -0.066 m s(-1) over NH and increases +0.065 m s(-1) over SH with 4.0 degrees C GWL, especially for East Asia and South America, the decrease and increase are most significant, which reach -0.21 and +0.093 m s(-1), respectively. Changes in the temperature gradient induced by global warming could be the primary factor causing the interhemispheric asymmetry of future NSWS changes. Intensified global warming induces the reduction in Hadley, Ferrell, and Polar cells over NH and the strengthening of the Hadley cell over SH could be another determinant of asymmetry changes in NSWS between two hemispheres.
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| 4. |
- Zhang, Gangfeng, et al.
(författare)
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Uneven Warming Likely Contributed to Declining Near-Surface Wind Speeds in Northern China Between 1961 and 2016
- 2021
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Ingår i: Journal of Geophysical Research-Atmospheres. - : American Geophysical Union (AGU). - 2169-897X .- 2169-8996. ; 126:11
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Tidskriftsartikel (refereegranskat)abstract
- A decline in mean near-surface (10 m) wind speed has been widely reported for many land regions over recent decades, yet the underlying cause(s) remains uncertain. This study investigates changes in near-surface wind speed over northern China from 1961 to 2016, and analyzes the associated physical mechanisms using station observations, reanalysis products and model simulations from the Community Atmosphere Model version 5.1 (CAM5). The homogenized near-surface wind speed shows a significantly (p < 0.05) decline trend of -0.103 m s(-1 )decade(-1), which stabilized from the 1990s onwards. Similar negative trends are observed for all seasons, with the strongest trends occurring in the central and eastern parts of northern China. Fast warming has occurred at high-latitudes (i.e., >50 degrees N) in recent decades, which has weakened the annual and seasonal meridional air temperature gradient (-0.33 degrees C to -0.12 degrees C dec(-1), p < 0.05, except autumn) between these regions (50 degrees-60 degrees N, 75 degrees-135 degrees E) and the northern China zone (35 degrees-45 degrees N, 75 degrees-135 degrees E). This caused a significant (p < 0.05) decrease in annual and seasonal pressure gradient (-0.43 to -0.20 hPa dec(-1)) between the two zones, which contributed to the slowdown of winds. CAM5 simulations demonstrate that spatially uneven air temperature increases and near-surface wind speed decreases over northern China can be realistically reproduced using the so-called "all forcing" simulation, while the "natural only forcing" simulation fails to realistically simulate the uneven warming patterns and declines in near-surface wind speed over most of northern China, except for summer.
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