Modeling the contributions of Northern Hemisphere dust sources to dust outflow from East Asia

2019 ◽  
Vol 202 ◽  
pp. 234-243 ◽  
Author(s):  
Zhiyuan Hu ◽  
Jianping Huang ◽  
Chun Zhao ◽  
Jiangrong Bi ◽  
Qinjian Jin ◽  
...  
Keyword(s):  
East Asia ◽  
Northern Hemisphere ◽  
Dust Sources

scholarly journals Lengthening of summer season over the Northern Hemisphere under 1.5°C and 2.0°C global warming

2021 ◽  
Author(s):  
Bo-Joung Park ◽  
Seung-Ki Min ◽  
Evan Weller
Keyword(s):  
Global Warming ◽  
East Asia ◽  
Northern Hemisphere ◽  
Climate Model ◽  
Global Climate ◽  
Global Climate Model ◽  
Late Summer ◽  
Industrial Condition ◽  
Summer Season ◽  
Hot Days

Abstract Summer season has lengthened substantially across Northern Hemisphere (NH) land over the past decades, which has been attributed to anthropogenic greenhouse gas increases. This study examines additional future changes in summer season onset and withdrawal under 1.5℃ and 2.0℃ global warming conditions using multiple atmospheric global climate model (AGCM) large-ensemble simulations from the Half a degree Additional warming, Prognosis and Projected Impacts (HAPPI) project. Five AGCMs provide more than 100 runs of 10-year length for three experiments: All-Hist (current decade: 2006-2015), Plus15, and Plus20 (1.5℃ and 2.0℃ above pre-industrial condition, respectively). Results show that with 1.5℃ and 2.0℃ warmer conditions summer season will become longer by a few days to weeks over entire NH lands, with slightly larger contributions by delay in withdrawal due to stronger warming in late summer. Stronger changes are observed more in middle latitudes than high latitudes and largest expansion (up to three weeks) is found over East Asia and the Mediterranean. Associated changes in summer-like day frequency is further analyzed focusing on the extended summer edges. The hot days occur more frequently in lower latitudes including East Asia, USA and Mediterranean, in accord with largest summer season lengthening. Further, difference between Plus15 and Plus20 indicates that summer season lengthening and associated increases in hot days can be reduced significantly if warming is limited to 1.5℃. Overall, similar results are obtained from CMIP5 coupled GCM simulations (based on RCP8.5 scenario experiments), suggesting a weak influence of air-sea coupling on summer season timing changes.

Typification of the Mediterranean endemic conifer Juniperus turbinata (Cupressaceae)

Phytotaxa ◽  
2017 ◽  
Vol 302 (2) ◽  
pp. 165 ◽  
Author(s):  
PEDRO PABLO FERRER-GALLEGO ◽  
ROBERTO NAZZARO ◽  
INMACULADA FERRANDO ◽  
EMILIO LAGUNA
Keyword(s):  
North America ◽  
East Asia ◽  
Northern Hemisphere ◽  
Canary Islands ◽  
Mediterranean Region ◽  
The Mediterranean ◽  
Semi Arid

The genus Juniperus Linnaeus (1753: 1038) (Cupressaceae Gray, nom. cons.) is a major component of arid and semi-arid tree/shrub ecosystems throughout the Northern Hemisphere (Thorne 1972, Adams 2004, 2008, 2014, Farjon 2005). The genus is monophyletic (Adams 2004, 2008, 2014, Little 2006, Mao et al. 2010), and three monophyletic sections are currently recognized: J. sect. Caryocedrus Endlicher (1847: 2), with one species in the Mediterranean; J. sect. Juniperus, with nine species in East Asia and the Mediterranean plus the circumboreal J. communis Linnaeus (1753: 1040); and J. sect. Sabina Spach (1841: 291), with 56 species distributed in southwestern North America, Asia and the Mediterranean region, with outliers in Africa and the Canary Islands.

scholarly journals Competing effects of nitrogen deposition and ozone exposure on Northern hemispheric terrestrial carbon uptake and storage, 1850–2099

2020 ◽  
Author(s):  
Martina Franz ◽  
Sönke Zaehle
Keyword(s):  
Air Pollution ◽  
East Asia ◽  
Nitrogen Deposition ◽  
Carbon Storage ◽  
Northern Hemisphere ◽  
21St Century ◽  
Ozone Exposure ◽  
Carbon Uptake ◽  
Northern Hemispheric ◽  
And Storage

Abstract. Tropospheric ozone and nitrogen deposition affect vegetation growth and thus the ability of the land biosphere to store carbon. However, the magnitude of this effect on the contemporary and future terrestrial carbon balance is insufficiently understood. Here, we apply an extended version of the O-CN terrestrial biosphere model that simulates the atmosphere to canopy transport of O3, its surface and stomatal uptake, as well as the ozone-induced leaf injury. We use this model to simulate past and future impacts of air pollution (ozone and nitrogen deposition) against a background of concurrent changes in climate and carbon dioxide concentrations (CO2) for two contrasting representative concentration pathways (RCP) scenarios (RCP2.6 and RCP8.5). The simulations show that O3-related damage considerably reduced Northern hemispheric gross primary production (GPP) and long-term carbon storage between 1850 and the 2010s. The ozone effect on GPP in the Northern hemisphere peaks at the end of the 20th century with reductions of 4 %, causing a reduction in the Northern hemispheric carbon sink of 0.4 Pg C yr−1. During the 21st century, ozone-induced reductions in GPP and carbon storage is projected to decline through a combination of air pollution control methods that reduce tropospheric O3 and the indirect effects of rising atmospheric CO2, which reduces stomatal uptake of ozone concurrent with increases of leaf-level water-use efficiency. However, in hotspot regions such as East Asia, the model simulations suggest a sustained decrease of GPP by more than 8 % during the 21st century. Regionally, ozone exposure reduces carbon storage at the end of the 21st century by up to 15 % in parts of Europe, the US and East Asia. These estimates are lower compared to previous studies, which partially results from the explicit representation of non-stomatal ozone destruction, which considerably reduces simulated ozone uptake by leaves and incurred injury. Our simulations suggest that ozone damage largely offsets the growth stimulating effect induced by nitrogen deposition in the Northern hemisphere until the 2050s. Thus, accounting for the stimulating effects of nitrogen deposition but omitting the detrimental effect of O3 might lead to an over estimation of carbon uptake and storage.

scholarly journals Impact of Arctic amplification on declining spring dust events in East Asia

2019 ◽  
Vol 54 (3-4) ◽  
pp. 1913-1935 ◽  
Author(s):  
Jun Liu ◽  
Dongyou Wu ◽  
Guangjing Liu ◽  
Rui Mao ◽  
Siyu Chen ◽  
...  
Keyword(s):  
East Asia ◽  
Northern Hemisphere ◽  
Surface Wind ◽  
Northern China ◽  
Temperature Gradients ◽  
Arctic Amplification ◽  
Dust Event ◽  
Snow Cover Extent ◽  
Spring Dust ◽  
Dust Events

AbstractDust aerosols play key roles in affecting regional and global climate through their direct, indirect, and semi-direct effects. Dust events have decreased rapidly since the 1980s in East Asia, particularly over northern China, primarily because of changes in meteorological parameters (e.g. surface wind speed and precipitation). In this study, we found that winter (December–January–February) Arctic amplification associated with weakened temperature gradients along with decreased zonal winds is primarily responsible for the large decline in following spring (March–April–May) dust event occurrences over northern China since the mid-1980s. A dust index was developed for northern China by combining the daily frequency of three types of dust event (dust storm, blowing dust, and floating dust). Using the empirical orthogonal function (EOF) analysis, the first pattern of dust events was obtained for spring dust index anomalies, which accounts for 56.2% of the variability during 1961–2014. Moreover, the enhanced Arctic amplification and stronger Northern Hemisphere annular mode (NAM) in winter can result in the anticyclonic anomalies over Siberia and Mongolia, while cyclonic anomalies over East Europe in spring. These results are significantly correlated with the weakened temperature gradients, increased precipitation and soil moisture, and decreased snow cover extent in the mid-latitude over Northern Hemisphere. Based on the future predictions obtained from the Fifth Climate Models Intercomparison Project (CMIP5), we found that the dust event occurrences may continually decrease over northern China due to the enhanced Arctic amplification in future climate.

scholarly journals Monsoons Climate Change Assessment

2021 ◽  
Vol 102 (1) ◽  
pp. E1-E19 ◽  
Author(s):  
Bin Wang ◽  
Michela Biasutti ◽  
Michael P. Byrne ◽  
Christopher Castro ◽  
Chih-Pei Chang ◽  
...  
Keyword(s):  
East Asia ◽  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Monsoon Rainfall ◽  
Extreme Rainfall ◽  
Cmip5 Models ◽  
High Confidence ◽  
Extreme Rainfall Events ◽  
Global Monsoon ◽  
Rainfall Events

AbstractMonsoon rainfall has profound economic and societal impacts for more than two-thirds of the global population. Here we provide a review on past monsoon changes and their primary drivers, the projected future changes, and key physical processes, and discuss challenges of the present and future modeling and outlooks. Continued global warming and urbanization over the past century has already caused a significant rise in the intensity and frequency of extreme rainfall events in all monsoon regions (high confidence). Observed changes in the mean monsoon rainfall vary by region with significant decadal variations. Northern Hemisphere land monsoon rainfall as a whole declined from 1950 to 1980 and rebounded after the 1980s, due to the competing influences of internal climate variability and radiative forcing from greenhouse gases and aerosol forcing (high confidence); however, it remains a challenge to quantify their relative contributions. The CMIP6 models simulate better global monsoon intensity and precipitation over CMIP5 models, but common biases and large intermodal spreads persist. Nevertheless, there is high confidence that the frequency and intensity of monsoon extreme rainfall events will increase, alongside an increasing risk of drought over some regions. Also, land monsoon rainfall will increase in South Asia and East Asia (high confidence) and northern Africa (medium confidence), decrease in North America, and be unchanged in the Southern Hemisphere. Over the Asian–Australian monsoon region, the rainfall variability is projected to increase on daily to decadal scales. The rainy season will likely be lengthened in the Northern Hemisphere due to late retreat (especially over East Asia), but shortened in the Southern Hemisphere due to delayed onset.

Reconstructing the intensity and location of Northern Hemisphere westerlies during the Plio-Pleistocene using marine sediments

2020 ◽  
Author(s):  
Jordan T. Abell ◽  
Gisela Winckler ◽  
Robert F. Anderson ◽  
Timothy Herbert
Keyword(s):  
East Asia ◽  
Northern Hemisphere ◽  
Marine Sediments ◽  
North Pacific ◽  
Land Surface ◽  
Western North Pacific ◽  
Time Interval ◽  
The North ◽  
Subarctic North Pacific ◽  
Dust Flux

<p>The warm Pliocene serves as an analogue for predicted warming over the next century. However, large uncertainties exist for atmospheric circulation and land surface conditions during the Pliocene. Dust transported by wind to locations of accumulation (terrestrial or marine) can provide a record of wind intensity and/or direction. Few dust flux records spanning the Plio-Pleistocene exist. As such, there is ample opportunity to use marine sediments to reconstruct changes in atmospheric conditions during a warmer-than-present world, as well as across the onset/intensification of Northern Hemisphere Glaciation (NHG). During this time, East Asia’s interior, the second largest source of mineral dust today, experienced aridification, occurring alongside a major reorganization of the subarctic North Pacific circulation which led to stratification of the surface ocean. Here, we present two North Pacific marine sediment records of extraterrestrial (ET) <sup>3</sup>He-derived terrigenous dust flux proxies (<sup>4</sup>He<sub>Terr</sub> and Th), along with a record of multiple paleoproductivity proxies (Ba<sub>xs</sub>, Opal, and C<sup>37</sup><sub>Total</sub>) for the period spanning ~2.5-4.5 Ma. Our results show that dust flux to the western North Pacific was relatively low and constant through the Pliocene up until ~2.7 Ma, with minor peaks during cooler phases from ~2.9-3.1 Ma. At ~2.7 Ma, concurrent with the intensification of NHG and formation of a permanent halocline cap in the subarctic North Pacific, dust fluxes increase dramatically. The central North Pacific record shows a less drastic shift in dust, but generally displays higher fluxes after ~3 Ma. Dust fluxes in East Asia and the North Pacific are consistent during this time interval, as are global dust fluxes from the North Atlantic, South Atlantic and North Pacific. Western North Pacific dust, SST, and paleoproductivity records point to northward-shifted and weakened Northern Hemisphere westerlies during the warm Pliocene, with evidence for strengthening and southward movement of the westerlies during glacials after ~2.7 Ma. Changes in both winds and dust production mechanisms are likely working in tandem to produce the coherent global dust signals.</p>

Different Climatic Effects of the Arctic and Antarctic ice Covers on Land Surface Temperature in the Northern Hemisphere: Application of Liang-Kleeman Information Flow Method and CAM4.0

2021 ◽  
Author(s):  
Shunyu Jiang ◽  
Haibo HU ◽  
William Perrie ◽  
Ning Zhang ◽  
Haokun Bai ◽  
...  
Keyword(s):  
North America ◽  
East Asia ◽  
Atmospheric Circulation ◽  
Northern Hemisphere ◽  
Information Flow ◽  
Air Temperature ◽  
The Arctic ◽  
High Latitudes ◽  
Flow Method ◽  
The Antarctic

Abstract Ice covers in high latitudes play important role in the global atmospheric circulation and abnormal temperature distribution. The observations have revealed the differences in the interannual variability of the Arctic and Antarctic ice covers, but their respective climate effect is not clear. The Liang-Kleeman information flow method is used to reveal the causal relationships from the sea ices of the Arctic and Antarctic to the global air temperature. The results point out that changes of the Arctic or Antarctic sea ices both have significant impacts on the global air temperature. Especially for the air temperature in East Asia and North America, the interannual variation of the Antarctic sea ice has an even stronger impact than the Arctic ice covers. This causality is further proved by the General Atmospheric Circulation Model (CAM4.0). In the numerical experiments, the ice covers in Arctic and Antarctic are changed individually or simultaneously as the forcing fields, and then the respective climate effects are analyzed. The results show that both the Arctic and Antarctic ice cover variations can change the intensity of atmospheric baroclinic disturbance in mid-high latitudes of individual hemisphere, generating wave energy transmission across the equator in the meridional direction, and eventually causing air temperature anomalies in both hemispheres. Furthermore, the Antarctic ice covers are closer to the mid-high latitude atmospheric jets in the southern hemisphere. Therefore, the changes of Antarctic ice covers lead to a larger atmospheric wave-activity flux response, and quickly spread to the northern hemisphere, causing more significant temperature anomalies over the East Asia and North America.

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