Surface temperature lapse rates over complex terrain: Lessons from the Cascade Mountains
Abstract
The typically sparse distribution of weather stations in mountainous terrain inadequately resolves temperature variability. Accordingly, high-resolution gridding of climate data (for applications such as hydrological modeling) often relies on assumptions such as a constant surface temperature lapse rate (i.e., decrease of surface temperature with altitude) of 6.5°C km-1. Using an example of the Cascade Mountains, we describe the temporal and spatial variability of the surface temperature lapse rate, combining data from: (1) COOP stations, (2) nearby radiosonde launches, (3) a temporary dense network of sensors, (4) forecasts from the MM5 regional model, and (5) PRISM geo-statistical analyses. On the windward side of the range, the various data sources reveal annual mean lapse rates of 3.9-5.2°C km-1, substantially smaller than the often-assumed 6.5°C km-1. The data sets show similar seasonal and diurnal variability, with lapse rates smallest (2.5-3.5°C km-1) in late-summer minimum temperatures, and largest (6.5-7.5°C km-1) in spring maximum temperatures. Geographic (windward versus lee side) differences in lapse rates are found to be substantial. Using a simple runoff model, we show the appreciable implications of these results for hydrological modeling.
- Publication:
-
Journal of Geophysical Research (Atmospheres)
- Pub Date:
- July 2010
- DOI:
- 10.1029/2009JD013493
- Bibcode:
- 2010JGRD..11514122M
- Keywords:
-
- Atmospheric Processes: Climatology (1616;
- 1620;
- 3305;
- 4215;
- 8408);
- Hydrology: Instruments and techniques: modeling;
- Hydrology: Instruments and techniques: monitoring;
- Atmospheric Processes: Regional modeling;
- Atmospheric Processes: Mesoscale meteorology;
- mountain hydrology;
- snowpack;
- mountain meteorology