Hydrometeorological Observations

Background

Scientists in RAL’s Hydrometeorological Applications Program (HAP) are actively engaged in numerous observational studies aimed at improving understanding of critical processes that control various linkages in the water cycle.  In FY2017 staff have engaged in several field observation efforts focused on winter precipitation, snowpack, snowmelt and runoff.  In addition to requiring a comprehensive scientific research strategy, these projects demand significant integration of instrument engineering and field work skills to collect research-quality data in Colorado’s extreme mountain environments. 

High-elevation monitoring for snowpack and water supply predictions

FY2017 Accomplishments

Figure 1:  HydroInspector web mapping service display of observation stations (white circles) and observation and model time series (right hand side time series plots) from the Upper Rio Grande observation and modeling project.
Figure 1:  HydroInspector web mapping service display of observation stations (white circles) and observation and model time series (right hand side time series plots) from the Upper Rio Grande observation and modeling project.

A network of snowpack, soil moisture, near surface meteorological and stream water level measurement stations was maintained in the Conejos River basin in southern Colorado (see Fig 1 below). White circles indicate location of NCAR measurement stations, blue squares are NRCS SNOTEL stations, green triangles are Colorado Division of Water Resources streamflow stations).   These stations were deployed in 2014 as part of the inter-agency Rio-SNO-FLO project which is performing observational and modeling based research aimed at improving the characterization and prediction of snowpack and seasonal water supplies in the headwaters of the Upper Rio Grande.  This work is being done in collaboration with the Conejos Water Conservancy District, the State of Colorado, the NOAA Severe Storms Laboratory and NASA’s Jet Propulsion Laboratory.  Research conducted during 2017 documented the performance of observed vs. modeled snowpack depth and near surface temperature, humidity and incoming solar radiation.  These results are summarized in a report to the State of Colorado (Gochis et al., 2016; Karsten et al. 2017).  The principal outcomes of this work were that research radars possessed significant skill in estimating mountain snowfall as validated by surface precipitation gauges in the southern Colorado region and that when used to drive a physics-based hydrologic model, resulting snowpack and streamflow simulations were significantly improved over simulations using background national analyses of precipitation. Additionally, it was also found that direct insertion of airborne lidar derived estimates of snowpack across the basin into a high resolution hydrologic model had a direct and positive impact on snowmelt driven seasonal water supply forecasts.  As a result, the State of Colorado is currently exploring financial alternatives to purchasing and deploying a gap-filling radar in the Upper Rio Grande basin.

Gochis, D.J, K. Howard, J. Busto, J. Deems, N. Coombs, L. Tang, I. Maycumber, K. Bormann, L. Karsten, A. Dugger, N. Langley, J. Mickey, T. Painter, M. Rchardson, and S.M. Skiles, 2016: Upper Rio Grande Basin Snowfall Measurement and Streamflow (RIO-SNO-FLOW) Forecasting Improvement Project. Project report submitted to the Colorado Water Conservation Board. Available online at: http://cwcb.state.co.us/public-information/publications/Pages/StudiesRep....

Karsten, L., D.J. Gochis, A. Dugger, K. Howard, L. Tang, J. Deems, T. Painter, G. Fall, C. Olheiser, 2017: Assessing the impact of operational meteorological forcings and experimental radar snowfall estimates on simulated snowpack conditions in the headwaters of the Upper Rio Grande River basin, In preparation.

Plans for FY2018

Figure 2: GoogleEarth map plot of the proposed installation sites (yellow balloons) of 4 new SNOTEL lite stations to be deployed in the Upper Taylor River Basin near Crested Butte, Colorado.  Inset photo shows the system hardware.
Figure 2: GoogleEarth map plot of the proposed installation sites (yellow balloons) of 4 new SNOTEL lite stations to be deployed in the Upper Taylor River Basin near Crested Butte, Colorado.  Inset photo shows the system hardware.

1.     Based on the findings of the RIO-SNO-FLO project in the Upper Rio Grande basin NCAR will install 4 new SNOTEL-Lite stations in the Upper Taylor River basin in southern Colorado. (see Figure 2 near Crested Butte, Colorado; station locations are shown with yellow bubbles. Inset shows photo of the station hardware.)  These stations are being built and installed in collaboration with the Upper Gunnison River Water Conservancy District (UGRWCD) and the Natural Resources Conservation Service (NRCS). Real-time measurements from these stations are being fed into the GOES satellite communication system and are being downloaded and integrated into the operational NRCS station data stream.  NCAR will also prepare and display this information for the UGRWCD using the NCAR/RAL HydroInspector tool along with other model-based snowpack and streamflow prediction products.

2.     Install and operate 5 additional new SNOLITE stations in the headwaters of the Conejos River basin in Upper Rio Grande basin in southern Colorado. This work is being done in collaboration with the Conejos Water Conservancy District, the State of Colorado, the NOAA Severe Storms Laboratory and NASA’s Jet Propulsion Laboratory. These stations will be used to validate model-estimated and remotely-sensed observations of snowpack, soil moisture, precipitation and other near surface meteorological conditions. Once installed, these data will also be telemetered via GOES satellite back to NCAR for quality control, archival, analysis and model evaluation.

Measurements and modeling of land surface hydrologic conditions in the North American Monsoon region

FY2017 Accomplishments

Over the past several years NCAR/RAL has collaborated with Arizona State University (ASU), the University of Sonora and other groups within Mexico to make observations of land surface hydrologic states and fluxes in the region of Northwest Mexico, within the climatic regime of the North American Monsoon region.  NCAR is a partner to this project, which is led by Prof. Enrique Vivoni of ASU and Prof. Enrico Yepez of U. of Sonora. Over the past year observational data collected from an intensively studied watershed in northern Sonora, the Rio San Miguel was processed and used in the calibration and validation of the community WRF-Hydro model in the simulation of semi-arid hydrologic responses to monsoon rainfall and in its ability to represent observed land surface flux conditions.  The results of this joint observation-modeling analysis documented the role surface topography and dynamic vegetation phenology has in controlling the spatial and temporal distribution of soil moisture and surface energy fluxes across a steep mountain terrain gradient. The integrated network of rainfall, soil moisture/temperature, radiation and eddy covariance energy flux instrumentation developed under this project has provided some of the first available measurements of these important hydrometeorological variables in complex terrain within the N. American Monsoon region. The results of this study have been summarized in Xiang et al., , 2017a and 2017b.  A significant outcome of this work has been encapsulated in a follow-on model-based study using a fully-coupled implementation of the WRF/WRF-Hydro system in the simulation and analyses of land-atmosphere coupling behavior within complex terrain regions of the N. American Monsoon. The findings from the fully coupled WRF/WRF-Hydro model experiments documented the differing ways vegetation structure and greenness and soil moisture impact land-atmosphere coupling pathways.  While positive anomalies of both soil moisture and vegetation density can increase simulated precipitation, the boundary layer structure between soil moisture and vegetation structure anomalies is quite different suggesting there are different energetics that drive the precipitation response, namely, deeper, more vigorous convective circulations versus lower condensation levels.  The results of this study are encapsulated in Xiang et al., 2017b.

Xiang, T., E.R. Vivoni, D.J. Gochis, and G. Mascaro, 2017a: On the diurnal cycle of surface energy fluxes in the North American monsoon region using the WRF-Hydro modeling system, In press, J. Geophys. Res. .

Xiang, T., E. Vivoni and D. Gochis, 2017b, Influence of Initial Soil Moisture and Vegetation Conditions on Monsoon Precipitation Events in Northwest México. In press submission to Atmosfera.

Plans for FY2017

This project is now complete, and no further observational plans exist at this time.

Bighorn Mountains Wintertime Cloud Seeding Feasibility Study

FY2017 Accomplishments

RAL participated in the deployment of a microwave radiometer and two high-resolution snow gauge sites in the northern region of the Big Horn Mountains in Wyoming for the winter of 2015–2016.  These measurements were collected to monitor liquid water path and snowfall in the region. For additional details on this project please see the Winter Weather section of this report.