Dr. Gina Henderson, Assistant Professor, Oceanography Department, United States Naval Academy
Research interests: Henderson’s research seeks to develop a better understanding of the role of snow cover in the hydrologic and global climate system. In particular, she studies the influences of snow on atmospheric circulation and climate change through surface-atmosphere interactions using both climate data records and global climate models.
Current research focus: Henderson’s current research focuses on the connections between tropical and extratropical weather patterns by examining variability within the Arctic system and how this variability is linked to tropical deep convection (known as the Madden-Julian Oscillation [MJO]) on intraseasonal (30-60 day) time scales. The MJO is an eastward moving disturbance of clouds, rainfall, wind, and pressure that is observed mainly over the Indian and Pacific Oceans. It consists of two parts, or phases: an enhanced rainfall (or convective) phase and a suppressed rainfall phase. The MJO traverses the planet in the tropics and returns to its initial starting point generally within 30 to 60 days. The movement of the MJO in the tropics influences both precipitation and temperature in the Northern Hemisphere, and MJO-influenced changes in the jet stream can lead to heavy precipitation along the U.S. West Coast along with colder than normal surface temperatures in Alaska and the Arctic. Few studies have related the intraseasonal variability of the MJO and its effect on Arctic sea ice concentrations or the extent of Northern Hemisphere snow. Understanding the connections among the tropics, the Arctic, and the mid-latitudes is crucial to understanding and predicting global climate.
Data products used:
- Northern Hemisphere Terrestrial Snow Cover Extent Daily 25km EASE-Grid 2.0 doi:10.5067/MEASURES/CRYOSPHERE/nsidc-0530.001 - this data set is available through the National Snow and Ice Data Center Distributed Active Archive Center (NSIDC DAAC) and was created as part of a NASA Making Earth System Data Records for Use in Research Environments (MEaSUREs) Program.
- MODIS/Terra Snow Cover Monthly L3 Global 0.05 Deg Climate Modeling Grid (CMG), Version 5, doi:10.5067/IPPLURB6RPCN - which is available through NSIDC DAAC
- Modern Era Retrospective-analysis for Research and Applications (MERRA) snow depth data set doi:10.5067/XOHTIIK0W9RK - these data are available through the Goddard Earth Sciences Data and Information Services Center (GES DISC).
Research findings: Henderson and her colleagues explored variability in the Arctic atmosphere and sea ice concentrations, and connections of this variability with phases of the MJO. Principal findings include evidence that the MJO affects the Arctic atmosphere in both the Arctic winter and summer seasons. In addition, variability in sea ice concentrations by phase of the MJO is found in both the Arctic summer and winter seasons. This variability is supported by corresponding changes in the state of the atmosphere.
Henderson and her colleagues also examined the variability of snow depth in the Northern Hemisphere meteorological spring season (March, April, and May) by phase of the MJO. The team found statistically significant regions of daily snow depth change differences in both North America and Eurasia. The magnitude of the observed anomalies in daily snow depth in some regions was found to exceed 100% of the monthly mean change, indicating that intraseasonal variability of spring-season daily snow depth change is physically significant.
Read about the research:
Barrett, B.S., Henderson, G.R. & Werling, J.S. (2015). The influence of the MJO on the intraseasonal variability of Northern Hemisphere spring snow depth. Journal of Climate, 28: 7250-7262. doi:10.1175/JCLI-D-15-0092.1
Henderson, G.R., Barrett, B.S. & Lafleur, D.M. (2013). Arctic sea ice and the Madden-Julian Oscillation (MJO). Climate Dynamics, 43(7): 2185-2196. doi:10.1007/s00382-013-2043-y
Henderson, G.R., Leathers, D.J. & Hanson, B. (2013). Circulation response to Eurasian versus North American anomalous snow scenarios in the Northern Hemisphere with an AGCM coupled to a slab ocean model. Journal of Climate, 26: 1502-1515. doi:10.1175/JCLI-D-11-00465.1
For more information