scholarly journals Quantifying light absorption and its source attribution of insoluble light-absorbing particles in Tibet an Plateau glaciers from 2013–2015

2018 ◽  
Author(s):  
Xin Wang ◽  
Hailun Wei ◽  
Jun Liu ◽  
Baiqing Xu ◽  
Mo Wang

Abstract. Amounts of insoluble light-absorbing particles (ILAPs) deposited on the surface of snow and ice can significantly reduce the snow albedo and accelerate the snow melting process. In this study, ~ 67 snow/ice samples were collected in 7 high mountain glaciers over the Tibetan Plateau (TP) regions from May 2013 to October 2015. The mixing ratio of black carbon (BC), organic carbon (OC), and mineral dust (MD) was measured using an integrating sphere/integrating sandwich spectrophotometer (ISSW) system associated with the chemical analysis by assuming the light absorption of mineral dust due to iron oxide. The results indicate that mass mixing ratios of BC, ISOC, and MD show a large variation of 10–3100 ng g-1, 10–17000 ng g-1, 10–3500 ng g-1, with a mean value of 218 ± 397 ng g-1, 1357 ± 2417 ng g-1, 241 ± 452 ng g-1 on TP glaciers during the entire snow field campaign, respectively. The chemical elements and the selected carbonaceous particles were also analyzed of the attributions of the particulate light absorption based on a positive matrix factorization (PMF) receptor model. On average, the industrial pollution (33.1 %), biomass/biofuel burning (29.4 %), and soil dust (37.5 %) were the major sources of the ILAPs in TP glaciers. Although the soil dust assumed to be the highest contributor to the mass loading of ILAPs, we noted that the averaged light absorption of BC (50.7 %) and ISOC (33.2 %) was largely responsible for the measured light absorption in the high mountain glaciers at the wavelengths of 450–600 nm.

2019 ◽  
Vol 13 (1) ◽  
pp. 309-324 ◽  
Author(s):  
Xin Wang ◽  
Hailun Wei ◽  
Jun Liu ◽  
Baiqing Xu ◽  
Mo Wang ◽  
...  

Abstract. The deposition of insoluble light-absorbing particles (ILAPs) on snow and ice surfaces can significantly reduce albedo, thereby accelerating the melting process. In this study, 67 ice samples were collected from seven glaciers located on the Tibetan Plateau (TP) between May 2013 and October 2015. The mixing ratios of black carbon (BC), organic carbon (OC), and mineral dust (MD) were measured with an integrating sphere/integrating sandwich spectrophotometer (ISSW) system, which assumes that the light absorption of MD is due to iron oxide (Fe). Our results indicate that the mass-mixing ratios of BC, OC, and Fe exhibit considerable variability (BC: 10–3100 ng g−1; OC: 10–17 000 ng g−1; Fe: 10–3500 ng g−1) with respective mean values of 220±400 ng g−1, 1360±2420 ng g−1, and 240±450 ng g−1 over the course of the field campaign. We observed that for wavelengths of 450–600 nm, the measured light absorption can be largely attributed to the average light absorption of BC (50.7 %) and OC (33.2 %). Chemical elements and selected carbonaceous particles were also analyzed for source attributions of particulate light absorption based on a positive matrix factorization (PMF) receptor model. Our findings indicate that on average, industrial pollution (33.1 %), biomass or biofuel burning (29.4 %), and MD (37.5 %) constitute the principal sources of ILAPs deposited on TP glaciers.


2017 ◽  
Author(s):  
Jianzhong Sun ◽  
Guorui Zhi ◽  
Regina Hitzenberger ◽  
Yingjun Chen ◽  
Chongguo Tian ◽  
...  

Abstract. Brown carbon (BrC) draws increasing attention due to its effects on climate and other fields. In China, household coal burned for heating/cooking purposes releases huge amounts of carbonaceous particles every year; however, BrC emissions have rarely been estimated in a persuasive manner due to the unavailable emission characteristics. Here 7 coals jointly covering geological maturity from low to high were burned in 4 typical stoves at both chunk and briquette styles. The optical integrating sphere (IS) method was applied to measure the emission factors (EFs) of BrC and BC via an iterative process using the different spectral dependence of light absorption for BrC and BC. It is found that (i) the average EFs of BrC for anthracite coal chunks and briquettes are (1.08 ± 0.80) g kg−1 and (1.52 ± 0.16) g kg−1, respectively, and those for bituminous coal chunks and briquettes are (8.59 ± 2.70) g kg−1 and (4.01 ± 2.19) g kg−1, respectively, reflecting a more significant decline of BrC EFs for bituminous coals than for anthracites due to briquetting, (ii) the BrC EF peaks at the middle of coal's geological maturity, displaying a bell shaped curve between EF and volatile matter (Vdaf), (iii) the calculated BrC emissions from China's residential coal burning amounted to 592 Gg (1 Gg = 109 g) in 2013, which is nearly half of China's total BC emissions, (iv) absorption Ångström exponent (AAEs) of all coal briquettes are higher than those of coal chunks, indicating that the measure of coal briquetting increases the BrC / BC emission ratio and thus offsets some of the climate cooling effect of briquetting, and (v) in the scenario of current household coal burning in China, solar light absorption by BrC (350–850 nm in this study) accounts for more than a quarter (0.265) of the total absorption. This implies the significance of BrC to climate modeling.


2017 ◽  
Vol 17 (7) ◽  
pp. 4769-4780 ◽  
Author(s):  
Jianzhong Sun ◽  
Guorui Zhi ◽  
Regina Hitzenberger ◽  
Yingjun Chen ◽  
Chongguo Tian ◽  
...  

Abstract. Brown carbon (BrC) draws increasing attention due to its effects on climate and other environmental factors. In China, household coal burned for heating and cooking purposes releases huge amounts of carbonaceous particles every year; however, BrC emissions have rarely been estimated in a persuasive manner due to the unavailable emission characteristics. Here, seven coals jointly covering geological maturity from low to high were burned in four typical stoves as both chunk and briquette styles. The optical integrating sphere (IS) method was applied to measure the emission factors (EFs) of BrC and black carbon (BC) via an iterative process using the different spectral dependence of light absorption for BrC and BC and using humic acid sodium salt (HASS) and carbon black (CarB) as reference materials. The following results have been found: (i) the average EFs of BrC for anthracite coal chunks and briquettes are 1.08 ± 0.80 and 1.52 ± 0.16 g kg−1, respectively, and those for bituminous coal chunks and briquettes are 8.59 ± 2.70 and 4.01 ± 2.19 g kg−1, respectively, reflecting a more significant decline in BrC EFs for bituminous coals than for anthracites due to briquetting. (ii) The BrC EF peaks at the middle of coal's geological maturity, displaying a bell-shaped curve between EF and volatile matter (Vdaf). (iii) The calculated BrC emissions from China's residential coal burning amounted to 592 Gg (1 Gg  =  109 g) in 2013, which is nearly half of China's total BC emissions. (iv) The absorption Ångström exponents (AAEs) of all coal briquettes are higher than those of coal chunks, indicating that the measure of coal briquetting increases the BrC ∕ BC emission ratio and thus offsets some of the climate cooling effect of briquetting. (v) In the scenario of current household coal burning in China, solar light absorption by BrC (350–850 nm in this study) accounts for more than a quarter (0.265) of the total absorption. This implies the significance of BrC to climate modeling.


2018 ◽  
Vol 12 (10) ◽  
pp. 3177-3186 ◽  
Author(s):  
Zhiyuan Cong ◽  
Shaopeng Gao ◽  
Wancang Zhao ◽  
Xin Wang ◽  
Guangming Wu ◽  
...  

Abstract. Cryoconite is a mixture of impurities and ice visually represented by dark colors present in the ablation zone of glaciers. As an important constituent of light-absorbing impurities on the glacier surface, iron oxides influence the radiative properties of mineral dust and thus its impact on ice melting processes. In particular, the distinct optical properties between hematite and goethite (the major iron oxide species) highlight the necessity to obtain accurate knowledge about their abundance and geochemical behavior. Cryoconite samples from five glaciers in different regions of the Tibetan Plateau (TP) and surroundings were studied. The iron abundance in the cryoconite from TP glaciers ranged from 3.40 % to 4.90 % by mass, in accordance with typical natural background levels. Because the light absorption capacity of mineral dust essentially depends on the presence of iron oxides (i.e., free iron), iron oxides were extracted and determined using diffuse reflectance spectroscopy. The ratios of free to total iron for the five glaciers ranged from 0.31 to 0.70, emphasizing that iron in the form of oxides should be considered rather than total iron in the albedo and radiative modeling. Furthermore, the goethite content in iron oxides (in mass fraction) ranged from 81 % to 98 %, showing that goethite was the predominant form among the glaciers. Using the abundance and speciation of iron oxides as well as their optical properties, the total light absorption was quantitatively attributed to goethite, hematite, black carbon (BC) and organic matters at 450 and 600 nm wavelengths. We found that the goethite played a stronger role than BC at shorter wavelengths for most glaciers. Such findings were essential to understand the relative significance of anthropogenic and natural effects, and then taking the proper mitigation measures.


2021 ◽  
Author(s):  
Chao Zhang ◽  
Meilian Chen ◽  
Shichang Kang ◽  
Fangping Yan ◽  
Chaoliu Li

<p>Carbonaceous particles play an important role in climate change, and the increase in their emission and deposition causes glacier melting in the Himalayas and the Tibetan Plateau (HTP). This implies that studying their basic characteristics is crucial for a better understanding of the climate forcing observed in this area. Thus, we investigated characteristics of carbonaceous particles at Yaze village, a typical remote site of southeastern HTP.  The results showed that the organic carbon and elemental carbon concentrations at this study site were 1.86 ± 0.84 and 0.18 ± 0.09 μg m<sup>-3</sup>, respectively, which were much lower than those reported for other frequently monitored stations in the same region. Thus, these values reflect the background characteristics of the study site. Additionally, the absorption coefficient per mass (α/ρ) of water-soluble organic carbon (WSOC) at 365 nm was 0.60 ± 0.19 m<sup>2</sup> g<sup>-1</sup>, which was lower than those reported for other remote stations in the HTP. This value could be attributed to a lower and higher contribution of mineral dust and secondary organic carbon, respectively. Multi-dimensional fluorescence analysis showed that the WSOC consisted of approximately 37% and 63% protein and humic-like components, respectively, and the latter was identified as the determining component of light absorption ability of the WSOC. Combined the significant relationships between WSOC and sulfate ion, potassium ion, and nitrate ion with the air masses at the study site originated primarily from South Asia, it is suggested that the levels of carbonaceous particles in Yaze village were predominantly influenced by emissions from South Asia.</p>


2021 ◽  
Vol 4 (2) ◽  
Author(s):  
Jacqueline Eng ◽  
Mark Aldenderfer

Anthropological research in the high-elevation regions of northwestern Nepal offers insights into the populationhistory of the Himalayan arc through a multi- and interdisciplinary approach that includes not only archaeologicaldata and historic and ethnographic accounts but also genomic, isotopic, and bioarchaeologicaldata, as well as innovative use of thermal niche modeling for paleoclimate reconstruction. Together these linesof evidence have allowed us to address project questions about human settlement into the region, including(1) sources of population movements into high-elevation environments of the Himalayan arc and (2) bioculturaladaptations to high-mountain environments. In this paper we compare research at several communalmortuary sites, each with a rich assemblage of material culture and human burials: Mebrak (400 B.C.–A.D. 50),Kyang (400–175 B.C.), and Samdzong (A.D. 450–650), as well as intriguing insights from finds in the earlier (ca.1250–450 B.C.) sites of Lubrak, Chokhopani, and Rhirhi. Our genomic findings demonstrate population originsfrom the Tibetan plateau, despite South Asian material culture recovered in early sites. Bioarchaeological findingsof low frequencies of non-specific stress and trauma indicate successful biocultural adaptation to highaltitudeconditions of hypoxia, cold, and low resource availability, potentially through buffering from exchangenetworks and local cultural practices, alongside high-altitude selected alleles. An integrative, multidisciplinaryapproach thus offers significantly greater opportunities for developing a more nuanced understanding of thepast processes of migration, settlement, and biocultural adaptation in the region. La investigación antropológica de las alturas del noroeste de Nepal nos proporciona conocimientos de la historiade la población del arco Himalaya a través de un enfoque multidisciplinario e interdisciplinario que incluyeno solamente datos arqueológicos y relatos históricos y etnográficos, sino también datos genómicos, isotópicos,y bioarqueológicos, tanto como uso innovador del modelado del nicho térmico para la reconstrucción paleoclimática.En conjunto, estas líneas de evidencia nos han permitido abordar temas sobre el asentamiento humanade la región, como: (1) los orígenes del movimiento hacia ambientes en las alturas del arco del Himalaya;y (2) las adaptaciones bioculturales necesarias para vivir en las alturas. En este artículo comparamos las investigacionesde varios mortuorios comunales que ofrecen conjuntos abundantes de entierros humanos y artefactosrelacionados: Mebrak (400 a.C.–d.C. 50), Kyang (400–175 a.C.), and Samdzong (d.C. 450–650), así como loshallazgos intrigantes de sitios anteriores (ca. 1250–450 a.C.) de Lubrak, Chokhopani, y Rhirhi. Nuestros datosgenómicos sugieren orígenes de le población del altiplano tibetano, a pesar del material que deriva del sur de Asia que se ha recuperado de los sitios mas tempranos. Los hallazgos bioarqueológicos demuestran niveles bajosde estrés y trauma inespecífico, y sugieren éxito en adaptación biocultural, a pesar de las condiciones de hipoxia,frio, y los recursos escasos en este ambiente. Es posible que alelos seleccionados a las alturas, junto con sistemasde intercambio y las costumbres locales contribuyeron al éxito de la adaptación. Por lo tanto, un enfoque multidisciplinarioque integra todas las evidencias ofrece una comprensión mas detallada de los procesos de migración,asentamiento, y adaptación biocultural de la región.


2021 ◽  
Author(s):  
Mickaël Lalande ◽  
Martin Ménégoz ◽  
Gerhard Krinner

<p>The High Mountains of Asia (HMA) region and the Tibetan Plateau (TP), with an average altitude of 4000 m, are hosting the third largest reservoir of glaciers and snow after the two polar ice caps, and are at the origin of strong orographic precipitation. Climate studies over HMA are related to serious challenges concerning the exposure of human infrastructures to natural hazards and the water resources for agriculture, drinking water, and hydroelectricity to whom several hundred million inhabitants of the Indian subcontinent are depending. However, climate variables such as temperature, precipitation, and snow cover are poorly described by global climate models because their coarse resolution is not adapted to the rugged topography of this region. Since the first CMIP exercises, a cold model bias has been identified in this region, however, its attribution is not obvious and may be different from one model to another. Our study focuses on a multi-model comparison of the CMIP6 simulations used to investigate the climate variability in this area to answer the next questions: (1) are the biases in HMA reduced in the new generation of climate models? (2) Do the model biases impact the simulated climate trends? (3) What are the links between the model biases in temperature, precipitation, and snow cover extent? (4) Which climate trajectories can be projected in this area until 2100? An analysis of 27 models over 1979-2014 still show a cold bias in near-surface air temperature over the HMA and TP reaching an annual value of -2.0 °C (± 3.2 °C), associated with an over-extended relative snow cover extent of 53 % (± 62 %), and a relative excess of precipitation of 139 % (± 38 %), knowing that the precipitation biases are uncertain because of the undercatch of solid precipitation in observations. Model biases and trends do not show any clear links, suggesting that biased models should not be excluded in trend and projections analysis, although non-linear effects related to lagged snow cover feedbacks could be expected. On average over 2081-2100 with respect to 1995-2014, for the scenarios SSP126, SSP245, SSP370, and SSP585, the 9 available models shows respectively an increase in annual temperature of 1.9 °C (± 0.5 °C), 3.4 °C (± 0.7 °C), 5.2 °C (± 1.2 °C), and 6.6 °C (± 1.5 °C); a relative decrease in the snow cover extent of 10 % (± 4.1 %), 19 % (± 5 %), 29 % (± 8 %), and 35 % (± 9 %); and an increase in total precipitation of 9 % (± 5 %), 13 % (± 7 %), 19 % (± 11 %), and 27 % (± 13 %). Further analyses will be considered to investigate potential links between the biases at the surface and those at higher tropospheric levels as well as with the topography. The models based on high resolution do not perform better than the coarse-gridded ones, suggesting that the race to high resolution should be considered as a second priority after the developments of more realistic physical parameterizations.</p>


2017 ◽  
Vol 11 (5) ◽  
pp. 2329-2343 ◽  
Author(s):  
Taylor Smith ◽  
Bodo Bookhagen ◽  
Aljoscha Rheinwalt

Abstract. High Mountain Asia (HMA) – encompassing the Tibetan Plateau and surrounding mountain ranges – is the primary water source for much of Asia, serving more than a billion downstream users. Many catchments receive the majority of their yearly water budget in the form of snow, which is poorly monitored by sparse in situ weather networks. Both the timing and volume of snowmelt play critical roles in downstream water provision, as many applications – such as agriculture, drinking-water generation, and hydropower – rely on consistent and predictable snowmelt runoff. Here, we examine passive microwave data across HMA with five sensors (SSMI, SSMIS, AMSR-E, AMSR2, and GPM) from 1987 to 2016 to track the timing of the snowmelt season – defined here as the time between maximum passive microwave signal separation and snow clearance. We validated our method against climate model surface temperatures, optical remote-sensing snow-cover data, and a manual control dataset (n = 2100, 3 variables at 25 locations over 28 years); our algorithm is generally accurate within 3–5 days. Using the algorithm-generated snowmelt dates, we examine the spatiotemporal patterns of the snowmelt season across HMA. The climatically short (29-year) time series, along with complex interannual snowfall variations, makes determining trends in snowmelt dates at a single point difficult. We instead identify trends in snowmelt timing by using hierarchical clustering of the passive microwave data to determine trends in self-similar regions. We make the following four key observations. (1) The end of the snowmelt season is trending almost universally earlier in HMA (negative trends). Changes in the end of the snowmelt season are generally between 2 and 8 days decade−1 over the 29-year study period (5–25 days total). The length of the snowmelt season is thus shrinking in many, though not all, regions of HMA. Some areas exhibit later peak signal separation (positive trends), but with generally smaller magnitudes than trends in snowmelt end. (2) Areas with long snowmelt periods, such as the Tibetan Plateau, show the strongest compression of the snowmelt season (negative trends). These trends are apparent regardless of the time period over which the regression is performed. (3) While trends averaged over 3 decades indicate generally earlier snowmelt seasons, data from the last 14 years (2002–2016) exhibit positive trends in many regions, such as parts of the Pamir and Kunlun Shan. Due to the short nature of the time series, it is not clear whether this change is a reversal of a long-term trend or simply interannual variability. (4) Some regions with stable or growing glaciers – such as the Karakoram and Kunlun Shan – see slightly later snowmelt seasons and longer snowmelt periods. It is likely that changes in the snowmelt regime of HMA account for some of the observed heterogeneity in glacier response to climate change. While the decadal increases in regional temperature have in general led to earlier and shortened melt seasons, changes in HMA's cryosphere have been spatially and temporally heterogeneous.


2012 ◽  
Vol 93 (11) ◽  
pp. 1713-1724 ◽  
Author(s):  
Kristen L. Rasmussen ◽  
Robert A. Houze

Flash floods on the edge of high terrain, such as the Himalayas or Rocky Mountains, are especially dangerous and hard to predict. The Leh flood of 2010 at the edge of the Himalayan Plateau in India is an example of the tragic consequences of such storms. The flood occurred over a high mountain river valley when, on three successive days, diurnally generated convective cells over the Tibetan Plateau gathered into mesoscale convective systems and moved off the edge of the Plateau over Leh. An easterly midlevel jet associated with a midlevel monsoon vortex over northern India and a high over Asia helped the convection organize into propagating mesoscale systems that moved over the edge of the Plateau. On the third day the mesoscale system moving off the plateau was greatly invigorated when it suddenly drew on moisture flowing upslope over the terrain. It gained maximum strength from this intake of moisture near Leh, and the heavy rains washed over the surrounding mountains and down and over the town.


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