A5064340746- Cryospheric studies and observations
- Hydrology and Watershed Management Studies
- Meteorological Phenomena and Simulations
- Climate change and permafrost
- Climate variability and models
- Precipitation Measurement and Analysis
- Arctic and Antarctic ice dynamics
- Soil Moisture and Remote Sensing
- Landslides and related hazards
- Flood Risk Assessment and Management
- Winter Sports Injuries and Performance
- Plant Water Relations and Carbon Dynamics
- Wind and Air Flow Studies
- Geophysics and Gravity Measurements
- Urban Heat Island Mitigation
- Soil and Unsaturated Flow
- Atmospheric aerosols and clouds
- Atmospheric and Environmental Gas Dynamics
- Hydrological Forecasting Using AI
- Hydrology and Sediment Transport Processes
- Remote Sensing in Agriculture
- Fluid Dynamics and Turbulent Flows
- Smart Materials for Construction
- Remote Sensing and LiDAR Applications
- Water resources management and optimization
University of California, Los Angeles
2015-2024
Jet Propulsion Laboratory
2023
University of Michigan
2023
Scripps Institution of Oceanography
2021
University of California, San Diego
2021
United States Geological Survey
2021
University of Massachusetts Amherst
2019
Irvine University
2017
University of California, Irvine
2017
Samueli Institute
2014
Abstract A newly developed state-of-the-art snow water equivalent (SWE) reanalysis dataset over the Sierra Nevada (United States) based on assimilation of remotely sensed fractional snow-covered area data Landsat 5–8 record (1985–2015) is presented. The method (fully Bayesian), resolution (daily and 90 m), temporal extent (31 years), accuracy provide a unique for investigating processes. verified (based comparison with 9000 station years in situ data) exhibited mean root-mean-square errors...
Based on a process-level modeling of the rain-on-snow (ROS) events in period 1950 to 2013 and warmer climate, we quantify historical future runoff contribution from ROS extreme floods source snowmelt large within conterminous United States (CONUS). We find that regions impacted most heavily by include West Coast, major mountain ranges western interior, Upper Midwest, Northeast, lower Appalachians. While 70% (upper 0.1%) these have some ROS, generated during accounts for less than 10% total...
Abstract The Surface Water and Ocean Topography (SWOT) mission will vastly expand measurements of global rivers, providing critical new data sets for both gaged ungaged basins. SWOT discharge products (available approximately 1 year after launch) provide all river that reaches wider than 100 m. In this paper, we describe how produced archived by the US French space agencies be computed from water surface elevation, width, slope ancillary data, along with expected accuracy. We present first...
Remotely sensed microwave measurements provide useful but indirect observations of surface soil moisture. Ground‐based are more direct very localized and limited in coverage. Model predictions a regional perspective rely on many simplifications approximations depend inputs that difficult to obtain over extensive areas. The only effective way achieve moisture estimates with the accuracy coverage required for hydrologic meteorological applications is merge information from satellites,...
Abstract This paper presents a newly proposed data assimilation method for historical snow water equivalent SWE estimation using remotely sensed fractional snow-covered area fSCA. The approach consists of particle batch smoother (PBS), which is compared to previously applied Kalman-based ensemble (EnBS) approach. methods were over the 27-yr Landsat 5 record at pillow and course in situ verification sites American River basin Sierra Nevada (United States). more densely vegetated thus...
Abstract The Sierra Nevada and Southern Cascades—California’s snowy mountains—are primary freshwater sources natural reservoirs for the states of California Nevada. These mountains receive precipitation overwhelmingly from wintertime storms including atmospheric rivers (ARs), much it falling as snow at higher elevations. Using a seven-decade record daily observed temperature well reanalysis downscaled climate projections, we documented historical future changes in accumulation snowlines. In...
Abstract Direct measurements of winter water loss due to sublimation were made in a sub‐alpine forest the Rocky Mountains Colorado. Above‐and below‐canopy eddy covariance systems indicated substantial losses winter‐season snow accumulation form snowpack (0·41 mm d −1 ) and intercepted (0·71 sublimation. The partitioning between these over under story components was highly dependent on atmospheric conditions near‐surface at below snow/atmosphere interface. High above‐canopy sensible heat...
Merging microwave radiances and modeled estimates of snowpack states in a data assimilation scheme is potential method for characterization. A radiance snow requires land surface model (LSM) coupled to radiative transfer (RTM). In this paper, we explore the degree fidelity required order yield benefits Specifically, characterize uncertainty Microwave Emission Model Layered Snowpacks (MEMLS) predictions by quantifying accuracy sensitivity following: (1) LSM layering (2) properties layers,...
Abstract A season-long, point-scale radiometric data assimilation experiment is performed in order to test the feasibility of snow water equivalent (SWE) estimation. Synthetic passive microwave observations at Special Sensor Microwave Imager (SSM/I) and Advanced Scanning Radiometer-Earth Observing System (AMSR-E) frequencies synthetic broadband albedo are assimilated simultaneously update snowpack states a land surface model using ensemble Kalman filter (EnKF). The effects vegetation...
A season‐long, multiscale, multifrequency radiometric data assimilation experiment is performed to test the feasibility of snow water equivalent (SWE) estimation. Synthetic passive microwave (PM) observations at Advanced Microwave Scanning Radiometer‐Earth Observing System frequencies and 25 km resolution synthetic near infrared (NIR) narrowband albedo corresponding Moderate Resolution Imaging Spectroradiometer band 5 (1230–1250 μ m) 1 are assimilated into a land surface model scheme using...
Abstract Snow accumulation and melt is highly variable in space time complex mountainous environments. Therefore, it necessary to provide high‐resolution spatially temporally distributed estimates of sub‐basin snow water equivalent (SWE) accurately predict the timing magnitude snowmelt runoff. In this study, we compare two reconstruction techniques (a commonly used deterministic vs a probabilistic data assimilation framework). The methods retrospectively estimate SWE from series remotely...
Abstract Despite the importance of snow in global water and energy budgets, estimates mountain equivalent (SWE) are not well constrained. Two approaches for estimating total range-wide SWE over Sierra Nevada, California, assessed: 1) global/hemispherical models remote sensing available continental United States (CONUS) plus southern Canada (CONUS+) to scientific community 2) regional climate model simulations via Weather Research Forecasting (WRF) Model run at 3, 9, 27 km. As no truth...
Abstract Snow water equivalent (SWE), particularly in mountains regions, has been an elusive hydrologic measurement. We examine the utility of a data assimilation approach to generate space‐time continuous estimates SWE from more readily available snow depth (SD) measurements. A multitemporal lidar set provides unique opportunity assimilate single SD images and verify posterior against at nonassimilation times. Application over three years shows significant improvement with average...
A new snow reanalysis method is presented that designed to jointly assimilate Landsat- and MODIS-derived (MODSCAG) fractional covered area (fSCA) characterize seasonal in remote regions like High Mountain Asia (HMA) where situ data severely lacking. The leverages existing readily available global datasets for forcing a model uses the fSCA retrievals along with ensemble prior estimates derive posterior using Bayesian framework. addresses MODIS viewing-geometry effects on by accounting viewing...
Abstract We present new insights on extratropical Andean snow climatology (27°S to 37°S) based the results from a 31 year high‐resolution reanalysis. The water equivalent (SWE) estimates were generated by integrating observed depletion data Landsat together with model forced Modern‐era Retrospective Analysis for Research and Applications. spatial resolution (180 m), geographic extent (175,000 km 2 ), temporal span (1984–2015) constitute an unprecedented set region. SWE reaches annual peak...
In response to the outbreak of COVID-19 pandemic, many governments instituted "stay-at-home" orders prevent spread coronavirus. The resulting changes in work and life routines had potential substantially perturb typical patterns urban water use. We present here an analysis how these pandemic responses affected California's consumption. Using demand modeling that fuses integrated use database, we first simulated a business-as-usual (non-pandemic) scenario for essentially all areas California....
Abstract. Seasonal snowpack is an essential component in the hydrological cycle and plays a significant role supplying water resources to downstream users. Yet snow equivalent (SWE) seasonal snowpacks, its space–time variation, remains highly uncertain, especially over mountainous areas with complex terrain sparse observations, such as High Mountain Asia (HMA). In this work, we assessed spatiotemporal distribution of SWE, obtained from new 18-year HMA Snow Reanalysis (HMASR) dataset, part...
Abstract Accurate characterization of peak snow water storage in High Mountain Asia (HMA) is essential for assessing the supply to over 1 billion downstream residents. Currently, such still relies on modeling due measurement scarcity. Here, eight global products were examined HMA using a newly developed Snow Reanalysis (HMASR) data set as reference. The focus intercomparison was annual storage, first‐order determinant warm‐season availability snow‐dominated basins. Across climatological...
Water stored in mountain snowpacks (i.e., snow water equivalent, SWE) represents an important but poorly characterized component of the terrestrial cycle. The Western United States reanalysis (WUS-SR) dataset is novel its combination spatial resolution (~500 m), extent (31°-49° N; 102°-125° W), and temporal continuity (daily over 1985-2021). WUS-SR generated using a Bayesian framework with model-based estimates updated through assimilation cloud-free Landsat fractional snow-covered area...
We demonstrate an ensemble‐based radiance assimilation methodology for estimating snow depth and grain size using ground‐based passive microwave (PM) observations at 18.7 36.5 GHz. A land surface model (LSM) was used to develop a prior estimate of the snowpack states, radiative transfer relate modeled states within data scheme. Snow bias −53.3 cm assimilation, −7.3 after assimilation. estimated by non‐assimilation‐based retrieval algorithm same PM had −18.3 cm. Our results suggest that into...