Oasis Effect Observed at Zhangye Oasis in the Hexi Corridor, China

Kai, Kenji; Matsuda, Masaki; Sato, Ritsuko

doi:10.2151/jmsj1965.75.6_1171

Cited by 39 publications

(41 citation statements)

References 4 publications

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“…It has been widely observed that the oases in our study region have lowered temperature comparing to the surrounding desert (i.e., oasis cooling effect), mainly due to the evaporative cooling caused by plant transpiration and irrigation (Kai et al 1997;Han 1999). According to the statistics in Dukhovny et al (2009), both the intensity and total water of irrigation in the five central Asian states decreased from 1994 to 2008 (Fig.…”

Section: Effects Of Land-use Changesmentioning

confidence: 84%

Temperature Changes in Central Asia from 1979 to 2011 Based on Multiple Datasets*

et al. 2014

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The arid and semiarid region in central Asia is sensitive and vulnerable to climate variations. However, the sparse and highly unevenly distributed meteorological stations in the region provide limited data for understanding of the region's climate variations. In this study, the near-surface air temperature change in central Asia from 1979 to 2011 was examined using observations from 81 meteorological stations, three local observation validated reanalysis datasets of relatively high spatial resolutions, and the Climate Research Unit (CRU) dataset. Major results suggested that the three reanalysis datasets match well with most of the local climate records, especially in the low-lying plain areas. The consensus of the multiple datasets showed significant regional surface air temperature increases of 0.368-0.428C decade 21 in the past 33 years. No significant contributions from declining irrigation and urbanization to temperature change were found. The rate is larger in recent years than in the early years in the study period. Additionally, unlike in many regions in the world, the temperature in winter showed no increase in central Asia in the last three decades, a noticeable departure from the global trend in the twentieth century. The largest increase in surface temperature was occurring in the spring season. Analyses further showed a warming center in the middle of the central Asian states and weakened temperature variability along the northwest-southeast temperature gradient from the northern Kazakhstan to southern Xinjiang. The reanalysis datasets also showed significant negative correlations between temperature increase rate and elevation in this complex terrain region.

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Section: Effects Of Land-use Changesmentioning

confidence: 84%

Temperature Changes in Central Asia from 1979 to 2011 Based on Multiple Datasets*

et al. 2014

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“…However, due to the surface albedo difference, R O n is always larger than R D n . In summer, Kai et al (1997) found that the latent heat flux is smaller over the desert (67 W m −2 ) than over the oasis (634 W m −2 ) in the HEIFE region:…”

Section: Surface Heat Flux Heterogeneitymentioning

confidence: 98%

“…According to the analysis of the observations from the Heihe River Basin in China, it was found that the soil heat flux is almost the same in the oasis and in the desert (Kai et al, 1997), i.e., G D ≈ G O , so Eq. (2) can be written as…”

Section: Surface Heat Flux Heterogeneitymentioning

confidence: 99%

Impacts of inhomogeneous landscapes in oasis interior on the oasis self-maintenance mechanism by integrating numerical model with satellite data

Meng

Lü

Zhang

et al. 2012

Hydrol. Earth Syst. Sci.

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Abstract. The impacts of inhomogeneity of the oasis interior on the oasis self-maintenance mechanism are investigated by using the mesoscale model MM5 (the fifth-generation Pennsylvania State University National Center for Atmospheric Research (NCAR) mesoscale model) with satellite observations of land use types, vegetation fraction and surface-layer soil moisture from MODIS (Moderate Resolution Imaging Spectroradiometer) data. Four simulations were performed, among which the CTL (control simulation) and MOD (moderated simulation with parameters replaced by MODIS data) were used to validate the model results; EXP1 (experiment 1) and EXP2 (experiment 2) were designed to study the inhomogeneity of oasis interior. Results show that the changes of oasis heterogeneity influence the surface heat-flux partitioning, which leads to a larger "cold-wet" effect over the oasis. Vertical sections of humidity illustrate the existence of a moisture-inversion level, and the deeper moisture inversion of EXP1 and EXP2 further indicates that the relative homogeneity in the oasis interior helps produce stronger humidity inversion over the oasis, thus limiting evaporation. This is further verified by the analysis of the secondary circulation, which shows that the more homogeneous land surface conditions lead to stronger secondary circulation and less turbulent drafts over the oasis interior, playing a positive role in the oasis self-maintenance and development.

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“…2). Several distinct daytime features are discovered during HEIFE: (1) the oasis is a wet-cold island capped by warm, dry air in the upper layer that would be advected from the surrounding desert (Tsukamoto et al, 1992; (2) a thermal inversion layer develops over the Zhangye Oasis from the surface to 8 m height with 2 8C difference when the wind speed was strong (Kai et al, 1997); and (3) water vapor flux is downward over the Gobi desert .…”

Section: Introductionmentioning

confidence: 99%