Over half a century, Professor Roger A. Pielke Sr. has played different roles, as a researcher, educator, and leader in atmospheric science and related fields. As one of the most accomplished atmospheric scientists in the world with an H-index of 100, he is the authority on the understanding and modeling of land surface impact (e.g., land cover and land use change, surface heterogeneities) on weather and climate, the co-developer of the Regional Atmospheric Modeling System (RAMS), the author of the most popular textbook on mesoscale meteorological modeling, and a pioneer in interdisciplinary science. He has also provided exceptional service to our field, including three Chief Editor positions that require substantial time commitments (including AMS Monthly Weather Review and Journal of the Atmospheric Sciences). The Pielke research group focuses on land-atmosphere interactions on the local, mesoscale, regional, and global scales. These interactions include biophysical, biogeochemical, and biogeographic effects. The RAMS model is a major tool used in this research. RAMS has been coupled to two different ecosystem-dynamics models (CENTURY and GEMTM) as part of these studies. Also applied is the CCM3 atmospheric global model from the National Center for Atmospheric Research (NCAR) in Boulder, Colorado. His studies range from the tropics into the high Arctic regions. His group has also applied RAMS to atmospheric-ocean interactions, including Arctic sea-ice feedbacks. He and his group members have investigated these nonlinear interactions within the Earth's climate system using the coupled RAMS model, as well as simplified nonlinear mathematical models.