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This study aimed to analyze the spectral features of alpine wetland grasses and evaluate three types of spectral feature computational methods. In situ spectra of alpine wetland grasses were collected in the northeastern Qinghai–Tibetan Plateau (Niaodao Wetland of International Importance and Ruoergai Wetland of International Importance), and spectral features were extracted using the revised vegetation spectral feature extraction (VSFE) model, wavelet transform, and the characteristic band selection method based on trivariate mutual information. These methods were then compared for their ability to amplify spectral separability and reflect grass properties, using the Jeffries–Matusita distance and relative vegetation parameters, respectively. The results show distinct spectral features of alpine wetland grasses within the band from 717.80 nm to 1050 nm. These differences are chiefly caused by leaf area index and chlorophyll content, but not plant taxonomy. Among the three spectral feature analysis methods, the revised VSFE model provides the most information for separating different alpine wetland grasses, as well as indices reflecting chlorophyll, leaf area index, and nitrogen. However, only 70 alpine wetland grass species pairs among 138 can be clearly classified within the band from 350 nm to 1050 nm. Further study on wetland grass species classification over wider band ranges should be implemented. This study also provides suggestions for selecting a spectral feature computational method in hyperspectral data processing. [ABSTRACT FROM PUBLISHER]

The 2021 M w 7.4 Maduo earthquake occurred on the left-lateral Kunlun Pass-Jiangcuo fault (KPJF) located within the Bayan Har block, Tibetan Plateau, caused an ∼165-km-long surface rupture and widespread ground deformation. This earthquake was well recorded by SAR images and our near-field GPS network during the coseismic and postseismic periods, providing a rare opportunity to shed light on the seismic and aseismic slip behaviors on the slow-slipping causative fault. Here, we constrain the coseismic slip distribution of the 2021 Maduo earthquake by the joint use of InSAR and near-field GPS observations. Then, time-dependent afterslip evolution is inverted from cGPS and InSAR time series in the first ∼160 days after the mainshock. The results show that the mainshock involves five asperities with a maximum slip of 4.79 m, including an E -W trending main fault and a secondary fault locates on the eastern end of the main fault. The significant energy released near Changmahe Township could be partialy explained by the fact that the seismogenic fault here cut through the pre-existing NW-SE trending faults. Afterslip played a dominant role in the early postseismic deformation, which has released seismic moment equivalent to an M w 6.78 earthquake, 10.3% of the coseismic moment. The seismic and aseismic slip distributions have complementary patterns in spatial, except for the overlaps on the Changmahe segment, suggesting the heterogeneity of frictional property on the fault plane. The rupture of the Maduo earthquake is located in the stress shadow induced by historical earthquakes, indicating the high accumulated stress on the KPJF. The stress level, as well as the potential seismic hazard on the ∼300-km-long seismic gap between the 2001 Kokoxili earthquake and the 2021 Maduo earthquake, is further raised by the historical events. • The Co- and postseismic deformations of the 2021 Maduo earthquake are recorded by SAR images and our near-field GPS network. • The mainshock involves five asperities with a maximum slip of 4.79 m. • Afterslip has released seismic moment equivalent to an M w 6.78 earthquake. • Overlaps between the seismic and aseismic slips are found on the Changmahe segment. • The Maduo earthquake is located in the stress shadow induced by historical events. [ABSTRACT FROM AUTHOR]

Koucha Lake, located in Qinghai Province, north-eastern Tibetan Plateau (NETP) at an elevation of 4530 m a.s.l. Occupies an ideal position to investigate the seasonal hydroclimatic variations and related surface processes during the Holocene. We re-investigated the lake and analysed a new sediment core from the deepest part of the lake. Grain size measurements and related endmember modelling analyses (EMMA) in combination with ostracod associations together with geochemical parameters and mineral compositions from core sediments were used as relevant proxies for hydro-climatic reconstruction.A comparison of δ18O/δD from various waters on the NETP indicates a clear depleted isotopic signature of non-monsoon moisture supply in comparison to summer rainfalls, highlighting the summer evaporation for δ18O enrichment, as a reference for interpreting δ18O values from lake sediments for various situations of hydrological balance. Based on the individual core chronology the multi-proxy data indicate a very low sedimentation rate over the entire period in accordance with the catchment topography and the absence of well-developed and constant river systems, limiting the flux of sediment supply to the lake. Thus, Koucha Lake remains almost a closed system since the Lateglacial, except for the early mid-Holocene part of the sequence. The coarser particle components and their representative endmembers for spring flood and permafrost thaw between 11.9 and 10.1 cal Ka BP and from 4.5 to ca. 1.0 cal Ka BP point to lower lake levels, influenced by long winter duration with dry summer interruptions, and lighter oxygen isotopes were preserved at low evaporations. Fine-grained sediments supplied by permafrost thaw associated with activating summer surface erosion led to lake level rise between 10.1 and 4.5 cal Ka BP and during the last 1000 years, with a maximum during 7.6–7.1 cal Ka BP. Their enriched δ18O values indicate extended summer duration and concomitant evaporation enhancement, albeit a positive hydrological balance. We suggest that the interannual latitudinal shifts of the intertropical convergence zone (ITCZ) and westerly Jet and attendant varying monsoon rain belt locations are responsible tracers for the variation of the hydrological budget of the lake and the variable spatio-temporal precipitation patterns in humid and (semi) arid regions in China. • Surface processes varied interannually and between cold and warm seasons during the Holocene. • Co-existence of long cold winter and dry summer extremes at high altitudes. • Synchronous/asynchronous patterns of heat and precipitation distribution between high/low altitudes in China. • These patterns correspond to the interannual latitudinal shifts of the ITCZ and the westerly jet. [ABSTRACT FROM AUTHOR]