Remote sensing of land surface conditions in arctic tundra regions for climatological applications using microwave radiometry.

Several climate change scenarios have predicted that the greatest changes would occur at high latitudes. In the arctic, long-term changes in temperature would be reflected, for example, in the growth or retreat of permafrost regions and in the response of the vegetation. Tundra-covered areas are a major terrestrial reservoir of carbon and changes in temperature and moisture will affect the storage and release of carbon by the tundra. The primary contribution of this dissertation is the development of a land surface process/radiobrightness (LSP/R) model for arctic tundra areas underlain by continuous permafrost. LSP models provide land-atmosphere boundary conditions for atmospheric circulation models (ACMs). The accuracy of the LSP parameterizations used by various ACMs is a significant source of uncertainty. By linking the tundra LSP/R model to satellite observations, the performance of the LSP model over areas such as the North Slope of Alaska may be monitored more widely and more frequently than is currently feasible. The scope of this dissertation includes the first step of this approach: the forward problem of matching tundra LSP/R model predictions with ground-based point observations of radiobrightness. The LSP/R model is a one-dimensional, physically-based model of energy and moisture fluxes inside the tundra and between the tundra and the atmosphere. While too computationally intensive to be an operational LSP model, it can be run retrospectively for selected regions to obtain much higher fidelity estimates of temperature and moisture profiles within tundra than would be available from any operational LSP model. The choice of a physical model is intended to provide insights into the land surface processes, guidance when developing or improving parameterizations for operational LSP models, and extendibility to regions with different vegetation and conditions. Model development was supported by data from a one-year field experiment, Radiobrightness Energy Balance Experiment 3 (REBEX-3). Microwave emission data and meteorological data were collected for one full annual freeze-thaw cycle at a tundra site on the North Slope. All of the data collected during REBEX-3 were collected using the Tower Mounted Radiometer System 2 (TMRS2), developed at the University of Michigan. A comparison of REBEX-3 ground-based microwave point observations and coincident SSM/I satellite observations is made, with attention given to atmospheric and scaling-related effects.Ph.D.Applied SciencesBiogeochemistryBiological SciencesEarth SciencesEcologyElectrical engineeringHydrologic sciencesPhysics, Atmospheric SciencePure SciencesRemote sensingUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/131691/2/9929864.pd