Changing Diurnal Energy Cycles Impact Net Water Vapor Fluxes in Mountain Watersheds

Mountain meteorology and hydrology

hydrology

The science that deals with water, its properties, circulation, or distribution on Earth's surface, and in the atmosphere through evapotranspiration.

Source: NASA earth observatory Source

are challenging to represent well in atmospheric models, owing to the fine spatial scales involved and the strong feedbacks between land, valley flows, and cloud formation. This scientific challenge has important implications for near-term weather predictions, as well as future climate projections. In a warmer climate, nighttime temperatures are expected to increase faster than daytime temperatures. Such changes will alter the daily cycle of feedbacks to the water cycle, which we do not currently understand well. This project will use data from the Surface Atmosphere Integrated field Laboratory (SAIL) and Study of Precipitation, the Lower Atmosphere and Surface for Hydrometeorology (SPLASH) campaigns to quantify the relationships between diurnally varying processes and improve our ability to model changes in the climate system and forecast mountain weather.

To better understand these processes, we will use the cloud, wind, and surface flux

flux

The amount of some type of particle or energy crossing a unit area per unit time.

Source: NRC Library Source

observations from the SAIL/SPLASH projects combined with satellite cloud cover maps and very high-resolution atmosphere and land surface modeling. These datasets will be used to quantify the feedbacks between surface fluxes, winds, and cloud cover. SAIL and SPLASH surface stations are placed along a transect connecting the upper and lower East River basin, allowing the measurement of valley flows accumulating over a range of airshed areas and the testing of relationship sensitivities to spatial scale.

We will test the causal relationships between these fluxes using the high spatial resolution Large Eddy Simulation (LES) capabilities of the Weather Research and Forecasting (WRF) model. LES simulations will simulate the feedbacks between distributed surface fluxes, organized temperature driven slope and valley winds, and convective initiation and cloud cover. We will perform sensitivity tests, altering the surface initial conditions, large scale environment, and thermodynamic feedbacks internal to the model.  Predictions from the LES numerical experiments will be compared with the observed sensitivities to identify the relationships for which theory (LES) corroborates the emergent properties of the system observed by SAIL (e.g., valley flow organization and cloud formation).

The relationships identified in this project will provide the science necessary to build models that better represent mountain hydroclimate.

hydroclimate

The scientific field that brings together hydrology and climate, including the impacts that water and its processes have on Earth’s climate, and the impacts of climate patterns and change on the global hydrological (or water) cycle.

Source: National Weather Service Source

The direct outcomes of this project will take the form of scientific peer-reviewed publications and cloud, land-surface, and LES datasets, which will be made available to other researchers for future study. We expect the scientific results to provide a quantitative

quantitative

Data represented numerically, including anything that can be counted, measured, or given a numerical value.

Source: National Library of Medicine Source

understanding of how expected changes to the diurnal energy cycle will impact mountain hydrology, particularly in mid-latitude interior continental climates of North America.