High Resolution Regional Climate Modeling of Summer Extremes for the United States Northeast

Understanding the effects of forcings, such as Land-cover and topography, on climate is an integral part of predicting future conditions in the Northeast Corridor (NEC), an important economic region in the US. As such, there is great value in high resolution modeling to understand how these forcings affect temperature and precipitation trends at the regional scale. This study focuses on the simulation of summer climate for mid-century (2040-2060), focused on key atmospheric variables that drive energy consumption and water resources in highly urbanized areas as those found in the region of study.

Simulations were undertaken using the Weather Research and Forecast (WRF) model at a finer resolution of 4 km for the NEC. The model parameterization incorporates a high resolution land use classification representative of the urban-rural gradients of the NEC. For model validation, WRF initial and lateral boundary conditions (ILBCs) are provided by NCEP/NCAR Reanalysis data. A sensitivity study to the different cumulus and microphysics parameterization schemes was performed to optimize the model's skill in predicting summer conditions in the NEC, using precipitation as a metric to evaluate model performance. A validation run of summer periods for the years of 2000-2010 was performed to assess biases in the model for the atmospheric variables of interest (i.e., air temperature, precipitation). Model output was compared to both daily local stations observations and seasonal gridded observation-based data sets showing good agreements.

Simulations for future climate conditions were performed using the Community Climate System Model (CCSM 3.0) output at 1.4 degree resolution for several scenarios as ILBCs corrected by biases estimated from present times. Selected summer periods are chosen considering extreme warm summer events as seen in the forcing model.

The overarching goal of these simulations is to provide insights on how trends in atmospheric variables can impact peak electric loads agriculture, biodiversity, water resources, as well as other ecosystem services under climate change projections for the NEC. The presentation will provide details of computational resources and climate physics challenges.