Priority 3: Improving Prediction of Weather , Climate, and Other Atmospheric Phenomena

Understanding of the Earth system is a prerequisite to predicting its behavior, the latter being however of a more direct use to many components of society. In that context, the key activities within the laboratory deal with improving climate models, exploring new approaches to prediction across scales and global and local weather prediction.

FY 2006 Accomplishments

Improving climate models is a key activity of this strategic priority. For centuries mankind has dreamed of being able to understand how the Earth's climate system works, NCAR scientists will enhance the Four-Dimensional Variational (4DVar) capability system of WRF through the inclusion of additional physics. The 4DVar system will be released to the community sometime before 2009, and is planned for operations at AFWA in 2008. and from that understanding being able to forecast the climate in the future. With the invention of the computer, and the development of numerical equations that represent the physics and dynamics of the climate, that dream is a reality. Comparing the on going climate model simulations to real world observations shows that the models need improvements to accurately represent the real world. To this end, researchers at NCAR with considerable collaboration with university and agency counterparts continue to develop state-of-the-art climate models, in particularly the NCAR Community Climate System Model. See projects related to this priority.

Another key activity is exploring new approaches to prediction across scales. NCAR weather scientists and climate scientists are working together to investigate the interplay of these two phenomena, in particular in relation to the scale of range domain. See projects related to this priority.

Contributing to this goal is global and local weather prediction. NCAR scientists are leaders in the field of weather forecast models and continue to look to improve them as well as to investigate extending their range from local and regional to global. Link to list of projects under #12. Below, we highlight our work in the The Observing-System Research and Predictability Experiment (THORPEX) project carried out in support of this priority. See projects related to this priority.

FY 2007 Plans

The following are the FY 2007 NCAR plans for Strategic Priority #3.

Improving climate models:

Address systematic CCSM biases in the tropics on seasonal and longer time scales, including the development of a Nested Regional Climate Model (NRCM) framework to document the importance of explicitly resolving mesoscale and microscale processes that govern weather and local climate but that may also have significant impacts on the large-scale circulation. Researchers plan to extend the complexity of CCSM to include the interactions of climate with biogeochemistry, atmospheric chemistry, ecosystems, glaciers and ice sheets, and anthropogenic environmental change. The CCSM-4 will be developed in FY07, with the goal of freezing the model code by the end of 2008. In addition to several other improvements, this version will most likely have new components for the carbon cycle and interactive atmospheric chemistry.

Use the CAM-Chem model to explore the impact of climate change in the Arctic due to anticipated methane release and changes in biomass fires.

Use the CAM-Chem model in combination with assimilation of a larger suite of data available from the increasing number of near-global tropospheric measurements of chemical constituents to explore regions of the globe prone to and the processes responsible for extreme pollution events (chemical weather).

Exploring new approaches to prediction across scales:

Analyze the output of the NCAR Nested Regional Climate Model to better understand why predictions of the Madden-Julian Oscillation (MJO) were inadequate. This work is a first step toward acting on the recommendations of the workshop on tropical convection held in Trieste, Italy in November 2006.

Analyze the data from the pilot driftsonde effort to study the hurricane genesis campaign.

Global and local weather prediction:

Develop and test new WRF model capabilities, such as gravity-wave absorption at the upper boundary to improve forecasting over mountainous terrain. NCAR scientists will conduct systematic testing of a newly developed positive definite advection scheme to see if model biases in over predicting precipitation at high resolution can be significantly reduced, and new monotonic advection schemes will also be developed and tested. Researchers are developing a new digital filter for WRF that should allow the model to spin-up convective activity more quickly and with less spurious noise. The impact of this filter on very short-term (0-6 h) cloud-scale Numerical Weather Predictions (NWP) forecasts will be evaluated in the coming year.

NCAR scientists plan to enhance the Four-Dimensional Variational (4DVar) capability system of WRF through the inclusion of additional physics in WRF's linear and adjoint models. The 4DVar system will be released to the community sometime before 2009 and is planned for operations at AFWA in 2008.

Further coordinate and focus on the Short Term Explicit Prediction (STEP) program (a workshop is scheduled for 4 Oct 2006), continued planning for forecasting demonstration efforts for the Beijing Olympics for 2007/2008, and initial planning for a mesoscale forecast experiment associated with the DC3 field program in 2009 or 2010.

On the following pages, we report on some of the highlights related to this priority.