Numerical simulations of the impacts of mountain on oasis effects in arid Central Asia

The oases in the mountain-basin systems of Central Asia are extremely fragile. Investigating oasis effects and oasis-desert interactions is important for understanding the ecological stability of oases. However, previous studies have been performed only in oasis-desert environments and have not considered the impacts of mountains. In this study, oasis effects were explored in the context of mountain effects in the northern Tianshan Mountains (NTM) using the Weather Research and Forecasting (WRF) model. Four numerical simulations are performed. The def simulation uses the default terrestrial datasets provided by the WRF model. The mod simulation uses actual terrestrial datasets from satellite products. The non-oasis simulation is a scenario simulation in which oasis areas are replaced by desert conditions, while all other conditions are the same as the mod simulation. Finally, the non-mountain simulation is a scenario simulation in which the elevation values of all grids are set to a constant value of 300 m, while all other conditions are the same as in the mod simulation. The mod simulation agrees well with near-surface measurements of temperature, relative humidity and latent heat flux. The Tianshan Mountains exert a cooling and wetting effects in the NTM region. The oasis breeze circulation (OBC) between oases and the deserts is counteracted by the stronger background circulation. Thus, the self-supporting mechanism of oases originating from the OBC plays a limited role in maintaining the ecological stability of oases in this mountain-basin system. However, the mountain wind causes the cold-wet'' island effects of the oases to extend into the oasis-desert transition zone at night, which is beneficial for plants in the transition region

Variability of the precipitation and moisture sources of the Tianshan Mountains, Central Asia

Das Tianshan-Gebirge, als „Wasserturm“ Zentralasiens, hat entscheidenden Einfluss auf die Wasserressourcen der Region. Untersuchungen von 1950 bis 2016 zeigen, dass der Jahresniederschlag in den meisten Teilen des Gebirges zunahm, außer im westlichen Tianshan, wo er abnahm. Es gibt hoch- und niedrigfrequente Schwankungen im Niederschlag mit 3-, 6-, 12- und 27-jährigen Quasiperioden. Auf Dekadenskala gab es zwei Trockenperioden (1950–1962, 1973–1984) und zwei Feuchtperioden (1962–1972, 1985–2016). Seit 2004 ist eine kontinuierliche Feuchtezunahme zu verzeichnen. Zusammenhänge wurden zwischen Zirkulationsmustern und dem Niederschlag identifiziert. Das East Atlantic-West Russia (EATL/WRUS)-Muster korreliert positiv mit dem Winter-Niederschlag. Das Scandinavia (SCAND)-Muster beeinflusst den Sommerniederschlag. Das Silk Road-Muster (SRP) war im Zeitraum 1964-1984 relevant. Die Feuchtigkeitsquellen für den Tianshan-Niederschlag stammen zu 93,2% von kontinentalen Quellen und nur begrenzt aus dem Ozean. Zentralasien ist die Hauptfeuchtequelle für das Gebirge. Im westlichen Tianshan kommt die Feuchtigkeit hauptsächlich von Zentralasien von April bis Oktober und von Westasien von November bis März. Im östlichen Tianshan tragen Ost- und Südasien sowie Sibirien konstant zur Feuchtigkeit im Sommer bei. Der Beitrag der Feuchtigkeit aus dem Nordatlantik zum Sommerniederschlag im nördlichen, zentralen und östlichen Tianshan zeigt einen abnehmenden Trend, obwohl dieser Beitrag ohnehin begrenzt ist. In Monaten mit extremem Winterniederschlag stammt die größte Zunahme der Feuchtigkeit im westlichen Tianshan aus Westasien, während Europa einen wichtigen Beitrag zu den extremen Winterniederschlägen im nördlichen Tianshan leistet. Im östlichen Tianshan ist die Feuchtigkeitszufuhr aus Ost- und Südasien sowie aus Sibirien während der extremen Niederschlagsmonate sowohl im Winter als auch im Sommer erhöht.The Tianshan Mountains, the "water tower" of Central Asia, are crucial water sources. Precipitation variability and water vapor transport impact water distribution. The study assessed 1950-2016 precipitation using Mann-Kendall tests and EEMD on GPCC data. Multi-timescale precipitation variations were analyzed with NCEP/NCAR reanalysis, and moisture sources during 1979–2017 with ERA–Interim data. Most of Tianshan had increasing annual precipitation, except Western Tianshan, which experienced a downtrend. Precipitation exhibited 3- and 6-year cycles and 12- and 27-year cycles. On the decadal scale, two dry and two wet periods occurred, with continuous humidification since 2004. A significant positive correlation was found between East Atlantic-West Russia EATL/WRUS circulation pattern and winter precipitation. SCAND influenced Tianshan's summer precipitation, with a wet period after 1988 due to enhanced water vapor flux. SCAND and EAP strengthened water vapor fluxes to Tianshan. SRP impacted Tianshan's summer precipitation during 1964–1984. About 93.2% of Tianshan's moisture comes from continental sources. Central Asia dominates moisture supply. Western Tianshan receives moisture mainly from Central Asia (April to October) and Western Asia (November to March). Almost 13.0% of Eastern Tianshan's summer moisture originates from East and South Asia and Siberia, with steady contributions. Moisture from the North Atlantic Ocean to summer precipitation in Northern, Central, and Eastern Tianshan shows a decreasing trend, but limited overall contribution. Extreme winter precipitation in Western Tianshan is linked to moisture from West Asia. Europe significantly contributes to extreme winter precipitation in Northern Tianshan. Eastern Tianshan sees enhanced moisture from East and South Asia and Siberia during extreme precipitation months in winter and summer

Climate–growth relationships of Schrenk spruce (Picea schrenkiana) along an altitudinal gradient in the western Tianshan mountains, northwest China

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Lagrangian Analysis of Moisture Sources of Precipitation in the Tianshan Mountains, Central Asia

The moisture sources of precipitation in the Tianshan Mountains, one of the regions with the highest precipitation in Central Asia during 1979–2017 are comprehensively and quantitatively summarized by using a Lagrangian moisture source detection technique. Continental sources provide about 93.2% of the moisture for precipitation in the Tianshan Mountain, while moisture directly from the ocean is very limited, averaging only 6.8%. Central Asia plays a dominant role in providing moisture for all sub‐regions of the Tianshan Mountains. For the Western Tianshan, moisture from April to October comes mainly from Central Asia (41.4%), while moisture from November to March is derived primarily from Western Asia (45.7%). Nearly 13.0% of moisture to precipitation for Eastern Tianshan in summer originates from East and South Asia, and the Siberia region. There is a significant decreasing trend in the moisture contribution of local evaporation and Central Asia in the Eastern Tianshan during winter. The contribution of moisture from Europe to summer precipitation in the Central and Eastern Tianshan and the contribution of the North Atlantic Ocean to summer precipitation in the Northern, Central, and Eastern Tianshan also exhibit a decreasing trend. The largest increase in moisture in Western Tianshan stems from West Asia during extreme winter precipitation months. Europe is also an important contributor to extreme precipitation in the Northern Tianshan. The moisture from East and South Asia and Siberia during extreme precipitation months in both winter and summer is significantly enhanced in the Eastern Tianshan.China Scholarship CouncilHumboldt‐Universität zu BerlinPeer Reviewe

Baseflow simulation using SWAT model in an inland river basin in Tianshan Mountains, Northwest China

Baseflow is an important component in hydrological modeling. The complex streamflow recession process complicates the baseflow simulation. In order to simulate the snow and/or glacier melt dominated streamflow receding quickly during the high-flow period but very slowly during the low-flow period in rivers in arid and cold northwest China, the current one-reservoir baseflow approach in SWAT (Soil Water Assessment Tool) model was extended by adding a slow- reacting reservoir and applying it to the Manas River basin in the Tianshan Mountains. Meanwhile, a digital filter program was employed to separate baseflow from streamflow records for comparisons. Results indicated that the two-reservoir method yielded much better results than the one-reservoir one in reproducing streamflow processes, and the low-flow estimation was improved markedly. Nash-Sutcliff efficiency values at the calibration and validation stages are 0.68 and 0.62 for the one-reservoir case, and 0.76 and 0.69 for the two-reservoir case. The filter-based method estimated the baseflow index as 0.60, while the model-based as 0.45. The filter-based baseflow responded almost immediately to surface runoff occurrence at onset of rising limb, while the model-based responded with a delay. In consideration of watershed surface storage retention and soil freezing/thawing effects on infiltration and recharge during initial snowmelt season, a delay response is considered to be more reasonable. However, a more detailed description of freezing/thawing processes should be included in soil modules so as to determine recharge to aquifer during these processes, and thus an accurate onset point of rising limb of the simulated baseflow

Study on Population Distribution, Morphological Structure and Physiological-Biochemical Characteristics of \u3cem\u3eDactylis glomerata\u3c/em\u3e in Different Geographical Areas of Tianshan Mountains of Xinjiang in China

As one important cool-season grass with high resource value, Dactylis glomerata has many characteristics such as good adaptability, high nutritional value and so on. It is one of the major cultivated species planted in high quality artificial grassland in the world. Xinjiang is one of the major areas have rich germplasm resource of wild Dactylis glomerata, and it is a natural gene pool. In order to protect and make good use of wild plant resources, this study focused on the distribution patterns, distribution regulation, morphological structure and physiological-biochemical characteristics of wild Dactylis glomerata grown in different geographical areas of Tianshan mountain of Xinjiang. It is aims to reveal the effects of geographical space and habitat on the population distribution in, morphological structure and physiological-biochemical characteristics of Dactylis glomerata

Comment on “Magnetostratigraphic study of the Kuche Depression, Tarim Basin, and Cenozoic uplift of the Tian Shan Range, Western China” Baochun Huang, John D.A. Piper, Shoutao Peng, Tao Liu, Zhong Li, Qingchen Wang, Rixiang Zhu

International audienceThe recent publication of “Magnetostratigraphic study of the Kuche Depression, Tarim Basin, and Cenozoic uplift of the Tian Shan Range,Western China” by B.C. Huang, J.D.A. Piper, S.T. Peng, T. Liu, Z. Li, Q.C. Wang, R.X. Zhu [Earth Planet. Sci. Lett., 2006, doi:10.1016/j.epsl.2006.09.020] discusses the Cenozoic uplift history of the Tianshan Mountains by studying the magnetostratigraphy of Paleogene to Neogene continental sediments from two sections located in the Kuche basin at the northern edge of the Tarim basin. To support their conclusion they reinterpreted a magnetostratigraphic study of the Yaha section, which lies ~ 10 km south of their sections, we previously published [J. Charreau, S. Gilder, Y. Chen, S. Dominguez, J.-P. Avouac, S. Sen, M. Jolivet, Y. Li and W. Wang, Magnetostratigraphy of the Yaha section, Tarim Basin (China): 11 Ma acceleration in erosion and uplift of the Tianshan Mountains, Geology 34(3), 2006, 181­184.]. Here, (1) we argue that the interpretations of the sedimentation rate changes they proposed for the Kuche sections are partially invalid, (2) we disagree with their reinterpretation of the age of the Yaha section, and (3) we think that the way they interpret their AMS data is incorrect

Macro- and microphysical characteristics of snowfall and non-snowfall clouds in the West Tianshan Mountains of China based on cloud radar

A Correction to this article was published on 10 February 2023. https://doi.org/10.1007/s00703-023-00953-6The macro- and microphysical characteristics of wintertime precipitating clouds and non-precipitating clouds over the West Tianshan Mountains, China, were analyzed with the use of Ka-band radar and weighing rain gauge observations. The data were collected from January to February 2019, December 2019, and from December 2020 to February 2021. Snowfall clouds mainly ranged from 0.15 similar to 2.50 km and had a reflectivity (Z) of mostly 10 33 dBZ. Non-snowfall clouds were primarily distributed within the height range of 2 similar to 8 km, and the Z values were within the range of - 22 similar to 15 dBZ. Compared with non-snowfall clouds, snowfall clouds have a higher particle water content (M) but a similar radial velocity (V). Light and moderate snowfall clouds were mainly located at heights of 0.15 similar to 3.50 km and had Z values concentrated from 5 similar to 24 dBZ. Heavy snowfall clouds were characterized by a Z of 5 similar to 30 dBZ below 3.5 km. The proportion of clouds with an M value> 0.1 g.m(-3) below 2 km was noticeably higher for heavy snow events than for light and moderate snow events. The differences in the distributions and values of snowfall cloud V values were small among the different snow types, and descending motions occurred below 6 km, with V ranging - 1.4 similar to - 0.3 m.s(-1). The heights of the non-snowfall cloud top and base during the day were lower than those at night. The snowfall cloud top did not show noticeable diurnal variations. The cloud top and base heights of the non-snowfall clouds both showed a single-peak distribution. The cloud top values of snowfall clouds exhibited bimodal distributions.Peer reviewe