Precipitation data and their uncertainty as input for rainfallinduced shallow landslide models

Physical models used toforecast the temporal occurrence of rainfall-induced shallow landslides are based on deterministic laws.Owing to the existing measuring technology and our knowledge of the physical laws controlling landslide initiation,model uncertainties are due to an inability to accurately quantify the model input parameters and rainfall forcing data.An uncertainty analysis of slope instability prediction provides a rationale for refining the geotechnical models.The Transient Rainfall Infiltration and Grid-based Regional Slope Stability-Probabilistic(TRIGRS-P)model adopts a probabilistic approach to compute the changes in the Factor of Safety(FS)due to rainfall infiltration.Slope Infiltration Distributed Equilibrium(SLIDE)is a simplified physical model for landslide prediction.The new code(SLIDE-P)is also modified by adopting the same probabilistic approach to allow values of the SLIDE model input parameters to be sampled randomly.This study examines the relative importance of rainfall variability and the uncertainty in the other variables that determine slope stability.The precipitation data from weather stations,China Meteorological Administration Land Assimilation System 2.0(CLDAS2.0),China Meteorological Forcing Data set precipitation(CMFD),and China geological hazard bulletin are used to drive TRIGRS,SLIDE,TRIGRS-P and SLIDE-P models.The TRIGRS-P and SLIDE-P models are used to generate the input samples and to calculate the values of FS.The outputs of several model runs with varied input parameters and rainfall forcings are analyzed statistically.A comparison suggests that there are significant differences in the simulations of the TRIGRS-P and SLIDE-P models.Although different precipitation data sets are used,the simulation results of TRIGRS-P are more concentrated.This study can inform the potential use of numerical models toforecast the spatial and temporal occurrence of regional rainfall-induced shallow landslides.

Simulation Study of Cloud Properties Affected by Heterogeneous Nucleation Using the GRAPES＿SCM during the TWP-ICE Campaign

This study used the Global/Regional Assimilation and PrEdiction System Single-Column Model(GRAPES_SCM)to simulate monsoon precipitation with deep convective cloud and associated cirrus during the Tropical Warm Pool International Cloud Experiment(TWP-ICE),especially during the active and suppressed monsoon periods.Four cases with different heterogeneous nucleation parameterizations were simulated by using the ensemble method.All simulations clearly separated the active and suppressed monsoon periods,and they reproduced the major characteristics of monsoonal cloud such as the total cloud hydrometeor mixing ratio distribution,and precipitation and radiation properties.The results showed that the number concentration production rate of different heterogeneous nucleation parameterizations varied substantially under the given temperature and water vapor mixing ratio.However,ice formation and precipitation during the monsoon period were affected only slightly by the different heterogeneous nucleation parameterizations.This study also captured clear competition between different ice formation processes.