Yunnan Institute of Meteorological science

Kunming, China

Yunnan Institute of Meteorological science

Kunming, China
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Zhao Q.-H.,Key Laboratory of Meteorological Disaster of Ministry of Education | Zhao Q.-H.,Nanjing University of Information Science and Technology | Sun J.-H.,Yunnan Institute of Meteorological Science
Wuli Xuebao/Acta Physica Sinica | Year: 2013

The variation of the surface mixed layer depth may affect not only the evolution of aquatic ecosystem, but also the temporal-spatial distribution of precipitation and climate in the basin. Based on the meteorological data and water temperature profiles observed in Erhai Lake (located in the Tibetan Plateau) and Taihu Lake (located in the Taihu Plain), the variation features and the mechanisms of the surface mixed layer depths are investigated. The stratification in Erhai Lake can be established and sustained in summer; the diurnal stratification in Erhai Lake can also be established, However, in both summer and autumn, stratification may exist in Taihu Lake. The time length of stratification is longer in Erhai Lake than that in Lake Taihu in the autumn. And the surface mixed layer depths in Erhai Lake are shallower than those in Taihu Lake in summer and autumn. The transformation frequency between establishment and destruction of stratification in Taihu Lake is faster than that in Erhai Lake, which illustrated that the response of water body in Taihu Lake to atmospheric variation is quicker than that in Erhai Lake. The water depth is a key factor which prevents such shallow lakes as Taihu Lake from establishing and maintainaning stratifications and in a suitable radiation condition the stratification will exist. The net radiation is a key factor that determines the stratification and the length of the time when the stratification can be sustained in lakes whose depths are the same as that of Erhai Lake. The research result in this paper is helpful for exploring the coupling mechanism of the turbulence of water and air and the evolution law of aquatic ecosystem. © 2013 Chinese Physical Society.


Wang L.,CAS Institute of Atmospheric Physics | Liu H.,CAS Institute of Atmospheric Physics | Sun J.,Yunnan Institute of Meteorological science | Feng J.,CAS Institute of Atmospheric Physics
International Journal of Biometeorology | Year: 2015

Based on the eddy covariance measurements from June 2011 to December 2013, the seasonal variations and the controls of water and CO2 fluxes were investigated over an alpine meadow in Lijiang, southwest China. The year 2012 had the largest total precipitation among years from 2011 to 2013 (1037.9, 1190.4, and 1066.1 mm, respectively). A spring drought event occurred from March to May 2012, and the peak normalized difference vegetation index (NDVI) in 2012 was the lowest. Throughout the whole year, net radiation (Rn), vapor pressure deficit, and air temperature (Ta) were the primary controls on evapotranspiration (ET), and Rn is the most important factor. The influence of Rn on ET was much more in the wet season (R2 = 0.93) than in the dry season (R2 = 0.28). In the wet season, the ratio of ET to equilibrium ET (ETeq) (0.92 ± 0.14; mean ± S.D.) did not show a clear seasonal pattern with NDVI when the soil water content (SWC) was usually more than 0.25 m3 m−3, indicating that ET could be predicted well by ETeq (or radiation and temperature). On half-hourly and daily scales, photosynthetic active radiation (PAR) and air temperature were the main meteorological factors in determining the net ecosystem production (NEP). The seasonal trends of NEP were closely related with the change of NDVI. The integrated NEP in the 2012 wet season (157.8 g C m−2 year−1) was 19.5 and 23.8 % lower than in the 2011 and 2013 wet season (207.0 and 196.1 g C m−2 year−1). The mean ET/ETeq for each of the wet seasons from 2011 to 2013 was 0.88. The 2012 spring drought and its reduction in NDVI decreased the total NEP significantly but had little effect on the total ET in the wet season. The different response of NEP and ET to the spring drought was attributed to the high SWC and small vapor pressure deficit during the wet season. © 2015 ISB


Yang R.,Yunnan University | Tao Y.,Yunnan University | Tao Y.,Yunnan Institute of Meteorological science | Cao J.,Yunnan University
Acta Meteorologica Sinica | Year: 2010

Based on the 500-hPa geopotential height, surface air temperature, and China summer rain-belt type data from 1978 to 2002, the spatial spectrum function sets which well represent the variation of large scale atmospheric circulations were obtained using the least square method. A mechanism for the interannual variation of the East Asia-Pacific teleconnection (EAP) wave train in early summer was identified with the low-order spectral method and the hypothesis-test method. The results indicate that, when nonlinear wavewave and wave-flow interactions on large scale are stronger in the inner dynamic process of the atmosphere, there are obvious nonlinear features in the evolution of the atmospheric circulation, and the EAP exhibits a negative-positive-negative ("- + -") spatial distribution in low to high latitudes in early summer. The corresponding EAP index is positive, which leads to a northward shift of the western Pacific subtropical high (WPSH) and the China rain-belt is located in the Huaihe River valley and its north in summer. On the contrary, when nonlinear wave-wave and wave-flow interactions on large scale are weaker, there appears a linear feature in the evolution of the atmospheric circulation, and the EAP shows a positive-negative-positive ("+ - +") spatial distribution in low to high latitudes. The corresponding EAP index is negative, which inhibits the WPSH against moving northward, and the China rain-belt is located in the Huaihe and Yangtze River valleys and their south.


PubMed | Yunnan Institute of Meteorological science and CAS Institute of Atmospheric Physics
Type: Journal Article | Journal: International journal of biometeorology | Year: 2016

Based on the eddy covariance measurements from June 2011 to December 2013, the seasonal variations and the controls of water and CO2 fluxes were investigated over an alpine meadow in Lijiang, southwest China. The year 2012 had the largest total precipitation among years from 2011 to 2013 (1037.9, 1190.4, and 1066.1 mm, respectively). A spring drought event occurred from March to May 2012, and the peak normalized difference vegetation index (NDVI) in 2012 was the lowest. Throughout the whole year, net radiation (Rn), vapor pressure deficit, and air temperature (Ta) were the primary controls on evapotranspiration (ET), and R n is the most important factor. The influence of R n on ET was much more in the wet season (R(2)= 0.93) than in the dry season (R(2)= 0.28). In the wet season, the ratio of ET to equilibrium ET (ETeq) (0.92 0.14; mean S.D.) did not show a clear seasonal pattern with NDVI when the soil water content (SWC) was usually more than 0.25 m(3) m(-3), indicating that ET could be predicted well by ETeq (or radiation and temperature). On half-hourly and daily scales, photosynthetic active radiation (PAR) and air temperature were the main meteorological factors in determining the net ecosystem production (NEP). The seasonal trends of NEP were closely related with the change of NDVI. The integrated NEP in the 2012 wet season (157.8 g C m(-2) year(-1)) was 19.5 and 23.8 % lower than in the 2011 and 2013 wet season (207.0 and 196.1 g C m(-2) year(-1)). The mean ET/ETeq for each of the wet seasons from 2011 to 2013 was 0.88. The 2012 spring drought and its reduction in NDVI decreased the total NEP significantly but had little effect on the total ET in the wet season. The different response of NEP and ET to the spring drought was attributed to the high SWC and small vapor pressure deficit during the wet season.

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