BER launches Environmental System Science Program. Visit our new website under construction!

U.S. Department of Energy Office of Biological and Environmental Research

BER Research Highlights


Model Parameter Choices and Their Impact on Precipitation Characteristics
Published: December 17, 2014
Posted: May 19, 2016

Simulating precipitation is very diffcult for global atmospheric models because precipitation requires accurate handling of many different processes to achieve success. Problems occur with errors in rain location, rates, and timing. A team of U.S. Department of Energy scientists from Pacific Northwest National Laboratory used a regional weather model to explore how global models will behave when used with higher resolutions more typical of regional atmospheric models. An important parameter in simulating clouds is the “convective timescale,” which represents how quickly convective clouds act on the surrounding atmosphere and whose resolution dependency is uncertain. Combining physics packages from the global Community Atmosphere Model version 5 (CAM5) with the regional Weather Research and Forecasting model for realistic weather conditions, they found that a shorter timescale results in a more accurate precipitation amount over the central United States during the simulated period. However, this short timescale worsens the precipitation diurnal cycle, with the convection too tightly linked to the daytime surface heating, and thus occurring too close to noon. Longer timescales greatly improve the diurnal cycle but result in less precipitation and thus produce a low bias. To investigate the simulated precipitation occurrence, strength, and diurnal cycle, the team compared the model results with observations using a grid with approximately ¼° grid spacing for a period in late April and May 2011 during the Midlatitude Continental Convective Clouds Experiment (MC3E). The analysis of rain rates shows that with longer timescales, the frequency distribution of rain can be improved, particularly for the extreme rain rates. Ultimately, without changing other aspects of the physics, a decision between accurate diurnal timing and rain amount must be made when choosing an appropriate convective timescale due to structural deficiencies in the cloud portion of the model. This information is important for designing climate models to operate at ¼° resolution during the next few years.

Reference: Gustafson, W. I., P.-L. Ma, and B. Singh. 2014. “Precipitation Characteristics of CAM5 Physics at Mesoscale Resolution During MC3E and the Impact of Convective Timescale Choice,” Journal of Advances in Modeling Earth Systems 6(4): 1271-87. DOI: 10.1002/2014MS000334. (Reference link)

Contact: Dorothy Koch, SC-23.1, (301) 903-0105, Shaima Nasiri, SC-23.1, 301-903-0207, Ashley Williamson, SC-23.1, (301) 903-3120
Topic Areas:

  • Research Area: Earth and Environmental Systems Modeling
  • Research Area: Atmospheric System Research

Division: SC-33.1 Earth and Environmental Sciences Division, BER

 

BER supports basic research and scientific user facilities to advance DOE missions in energy and environment. More about BER

Recent Highlights

Jan 11, 2022
No Honor Among Copper Thieves
Findings provide a novel means to manipulate methanotrophs for a variety of environmental and in [more...]

Dec 06, 2021
New Genome Editing Tools Can Edit Within Microbial Communities
Two new technologies allow scientists to edit specific species and genes within complex laborato [more...]

Oct 27, 2021
Fungal Recyclers: Fungi Reuse Fire-Altered Organic Matter
Degrading pyrogenic (fire-affected) organic matter is an important ecosystem function of fungi i [more...]

Oct 19, 2021
Microbes Offer a Glimpse into the Future of Climate Change
Scientists identify key features in microbes that predict how warming affects carbon dioxide emi [more...]

Aug 25, 2021
Assessing the Production Cost and Carbon Footprint of a Promising Aviation Biofuel
Biomass-derived DMCO has the potential to serve as a low-carbon, high-performance jet fuel blend [more...]

List all highlights (possible long download time)