Fengge Su

Evaluation of TRMM Multisatellite Precipitation Analysis (TMPA) and Its Utility in Hydrologic Prediction in the La Plata Basin

Abstract Satellite-based precipitation estimates with high spatial and temporal resolution and large areal coverage provide a potential alternative source of forcing data for hydrological models in regions where conventional in situ precipitation measurements are not readily available. The La Plata basin in South America provides a good example of a case where the use of satellite-derived precipitation could be beneficial. This study evaluates basinwide precipitation estimates from 9 yr (1998–2006) of Tropical Rainfall Measuring Mission (TRMM) Multisatellite Precipitation Analysis (TMPA; 3B42 V.6) through comparison with available gauged data and the Variable Infiltration Capacity (VIC) semidistributed hydrology model applied to the La Plata basin. In general, the TMPA estimates agreed well with the gridded gauge data at monthly time scales, most likely because of the monthly adjustment to gauges performed in TMPA. The agreement between TMPA and gauge precipitation estimates was reduced at daily time scal...

Evaluation of the Global Climate Models in the CMIP5 over the Tibetan Plateau

AbstractThe performance of 24 GCMs available in the fifth phase of the Coupled Model Intercomparison Project (CMIP5) is evaluated over the eastern Tibetan Plateau (TP) by comparing the model outputs with ground observations for the period 1961–2005. The twenty-first century trends of precipitation and temperature based on the GCMs’ projections over the TP are also analyzed. The results suggest that for temperature most GCMs reasonably capture the climatological patterns and spatial variations of the observed climate. However, the majority of the models have cold biases, with a mean underestimation of 1.1°–2.5°C for the months December–May, and less than 1°C for June–October. For precipitation, the simulations of all models overestimate the observations in climatological annual means by 62.0%–183.0%, and only half of the 24 GCMs are able to reproduce the observed seasonal pattern, which demonstrates a critical need to improve precipitation-related processes in these models. All models produce a warming tre...

Potential Utility of the Real-Time TMPA-RT Precipitation Estimates in Streamflow Prediction

AbstractThe potential utility of the real-time Tropical Rainfall Measuring Mission (TRMM) Multisatellite Precipitation Analysis real-time product 3B42RT (TMPA-RT) data for streamflow prediction, both through direct comparisons of TMPA-RT estimates with a gridded gauge product and through evaluation of streamflow simulations over four tributaries of La Plata basin (LPB) in South America using the two precipitation products, is investigated. Assessments indicate that the relative accuracy and the hydrologic performance of TMPA-RT-based streamflow simulations generally improved after February 2005. The improvements in TMPA-RT since 2005 are closely related to upgrades in the TMPA-RT algorithm in early February 2005, which include use of additional microwave sensors [Advanced Microwave Scanning Radiometer for Earth Observing System (AMSR-E) and Advanced Microwave Sounding Unit-B (AMSU-B)] and implementation of different calibration schemes. This study suggests considerable potential for hydrologic prediction ...

Climate Change on the Northern Tibetan Plateau during 1957–2009: Spatial Patterns and Possible Mechanisms

AbstractGridded daily precipitation, temperature minima and maxima, and wind speed are generated for the northern Tibetan Plateau (NTP) for 1957–2009 using observations from 81 surface stations. Evaluation reveals reasonable quality and suitability of the gridded data for climate and hydrology analysis. The Mann–Kendall trends of various climate elements of the gridded data show that NTP has in general experienced annually increasing temperature and decreasing wind speed but spatially varied precipitation changes. The northwest (northeast) NTP became dryer (wetter), while there were insignificant changes in precipitation in the south. Snowfall has decreased along high mountain ranges during the wet and warm season. Averaged over the entire NTP, snowfall, temperature minima and maxima, and wind speed experienced statistically significant linear trends at rates of −0.52 mm yr−1 (water equivalent), +0.04°C yr−1, +0.03°C yr−1, and −0.01 m s−1 yr−1, respectively. Correlation between precipitation/wind speed an...

Dynamics of Terrestrial Water Storage Change from Satellite and Surface Observations and Modeling

Abstract Terrestrial water storage (TWS) is a fundamental component of the water cycle. On a regional scale, measurements of terrestrial water storage change (TWSC) are extremely scarce at any time scale. This study investigates the feasibility of estimating monthly-to-seasonal variations of regional TWSC from modeling and a combination of satellite and in situ surface observations based on water balance computations that use ground-based precipitation observations in both cases. The study area is the Klamath and Sacramento River drainage basins in the western United States (total area of about 110 000 km2). The TWSC from the satellite/surface observation–based estimates is compared with model results and land water storage from the Gravity Recovery and Climate Experiment (GRACE) data. The results show that long-term evapotranspiration estimates and runoff measurements generally balance with observed precipitation, suggesting that the evapotranspiration estimates have relatively small bias for long averag...

A model for assessing effects of climate change on runoff in China

A model is established for assessing the effects of climate change on runoff in China based on the land surface parameterization scheme variable infiltration capacity (VIC). The entire area of China is represented by 2604 cells with a resolution of 60 km × 60 km for each cell. Forcing data, soil and vegetation parameters needed by the VIC model for the entire area of China are prepared. Daily forcing data, which are obtained from 740 stations between 1980 and 1990, are interpolated to the 60 km × 60 km grid system. The VIC model is run on every grid cell over the whole China, and a routing scheme is run offline with daily input of surface runoff and drainage from the VIC to get hydrograph at basin outlets. The spatial patterns of simulated runoff and mean annual precipitation are consistent very well. The results of monthly streamflow simulations over the Huaihe and Weihe River basins indicate that there is a good agreement between the observed and simulated values, and also initially indicate the rationality and feasibility of the evaluation model.

An application of the VIC-3L land surface model and remote sensing data in simulating streamflow for the Hanjiang River basin

The hydrologically based three-layer variable infiltration capacity (VIC-3L) land surface model with a new surface runoff model is applied to simulate streamflow for the Hanjiang River basin in China. The required soil parameters are derived from the soil classification information of global 5 min data provided by the National Atmospheric and Oceanic Administration (NOAA) Hydrology Office, the vegetation parameters are derived based on advanced very high resolution radiometer (AVHRR) and land data assimilation system (LDAS) information, and the forcing data are obtained through interpolation methods based on 740 meteorological stations. All of the data (i.e., soil, vegetation, and forcings) required by the VIC-3L model are compiled at 25 km × 25 km resolution for the Hanjiang River basin, and the daily forcing data are available for the period of 1980-1990. The VIC-3L model is applied to the Hanjiang River basin, and the VIC-3L simulated daily runoff is routed to the outlets of six streamflow stations and compared with the daily and monthly observed streamflow at the stations. The results show that the model can simulate the observations well.

Estimation of the Surface Water Budget of the La Plata Basin

Abstract The Variable Infiltration Capacity (VIC) land surface hydrology model forced by gridded observed precipitation and temperature for the period 1979–99 is used to simulate the land surface water balance of the La Plata basin (LPB). The modeled water balance is evaluated with streamflow observations from the major tributaries of the LPB. The spatiotemporal variability of the water balance terms of the LPB are then evaluated using offline VIC model simulations, the 40-yr European Centre for Medium-Range Weather Forecasts Re-Analysis (ERA-40), and inferences obtained from a combination of these two. The seasonality and interannual variability of the water balance terms vary across the basin. Over the Uruguay River basin and the entire LPB, precipitation (P) exceeds evapotranspiration (E) and the basins act as a moisture sink. However, the Paraguay River basin acts as a net source of moisture in dry seasons (strong negative P − E). The annual means and monthly time series of ERA-40 P are in good agreem...

Quantifying the contribution of glacier meltwater in the expansion of the largest lake in Tibet

Lake Siling Co is currently the largest endorheic lake in Tibet, and the lake surface area has expanded by about 40% since the 1970s, with a remarkable acceleration after 1999. In this study, a hydrologic modeling framework was established by linking the Variable Infiltration Capacity (VIC) land surface hydrologic model with the degree-day glacier-melt model over the Lake Siling Co basin, with an aim to quantify the contribution of each runoff component to changes in the lake storage. We found that glacier melt contributed to less than 10% of the total water input to the lake during 1979-2013, while precipitation-induced runoff in nonglacierized area was responsible for about 67-75%. The mean annual water input to the lake increased by 2.15x10(9)m(3)yr(-1) in 2000-2013 relative to that in 1979-1999. The amount of precipitation over the lake surface, precipitation-induced runoff, and glacier-melt runoff accounted for 13%, 82%, and 5% of this total increase, respectively, suggesting that the substantial expansion of Siling Co in the 2000s was mostly due to the increase in precipitation-induced runoff. When modeling lake level changes during 1979-2013, we found that the water level rose by 14.1m when glacier melt was included and by only 10.5m, a reduction of about one fourth, when glacier melt was removed. It is concluded that glacier melt played an important role in controlling the water level of Siling Co, although it only contributed less than 10% of water input to the lake during 1979-2013.

Progress in Hydrological Modeling over High Latitudes: Under Arctic Climate System Study (ACSYS)

We review achievements in hydrological modeling over high latitudes during ACSYS, including development and improvement of land surface schemes in representing cold processes, large-scale hydrological modeling over high-latitude river basins, and estimates of freshwater river inflow to the Arctic Ocean. ACSYS hydrological modeling efforts were closely linked to the GEWEX continental-scale experiments (CSEs) and to the Project for Intercomparison of Land-Surface Parameterization Schemes (PILPS). Results in this review are mainly from PILPS 2(e), MAGS, BALTEX, GAME-Siberia (the latter three of which are CSEs), and other studies related to ACSYS. Based on these achievements from the 10 years efforts, the ACSYS scientific strategy for hydrology, which included adaptation of macroscale hydrological modes developed in the framework of GEWEX to Arctic (high-latitude) climate conditions and development of physical (conceptual) or parametric mesoscale hydrologic models for selected river catchments within the Arctic region, was implemented more or less as envisaged in the ACSYS Implementation Plan. In spite of major advances in high-latitude hydrological modeling during the ACSYS era, there remain important problems in parameterization of snow, frost, and lake/wetlands cold processes within climate and hydrology models and in linkages between atmospheric and hydrological models.