The objective of this proposal is to improve the understanding of the scientific role that soil moisture and surface temperature play in affecting the surface energy balance, sub-surface thermal dynamics and vegetation distribution. Soil moisture storage in the active layer seems to be the key variable in understanding most ecological process interactions and atmospheric/terrestrial linkages in arctic regions. As such, we will focus our field measurement program and modeling efforts on understanding the interdependent controls on and responses to soil moisture. A basin scale water balance is the indisputable method to quantify hydrologic processes and enable valid comparisons among watersheds in different regions. Our field instrumentation at each site will include continuously recording soil moisture and temperature sensors, precipitation gauges, air temperature, relative humidity, and wind speed sensors. Portable eddy correlation towers will be established at every site for approximately one-week periods during at least two growing seasons. We will measure runoff in three small basins on the Seward Peninsula. Utilizing all of these field data, we will refine and/or adapt our coupled model of thermal and hydrologic processes to address questions related to physical differences among watersheds existing in slightly different climatic regimes of the Arctic. Techniques to estimate soil moisture have been developed under previous ARCSS sponsored research. For this study, we will utilize ERS-2, RADARSAT, and JERS SAR imagery collected or archived at the Alaska SAR Facility. We will measure surface soil moistures over relatively large areas in representative vegetation zones to characterize moisture during satellite viewing. These soil moisture data sets derived from remotely sensed data will be combined with hydrologic model simulations to permit extrapolation over large areas. During the course of this study, we hope to determine soil moisture levels with good to high accuracy over a wide range of landscape types. We believe that classification of soil moisture into a minimal number of levels may provide adequate information to calculate latent and sensible heat fluxes over broad areas with acceptable accuracy. Further, we recognize that these soil moisture classifications will provide valuable data for regional analyses on carbon flux, vegetation distributions, and soil genesis. Extensive amounts of soil moisture measurements will be collected in the field during satellite over-flights for both training a neural network and verification testing.

Three small watersheds will be studied near the runway at Kougarok approximately 80 miles north of Nome on the Seward Peninsula. The three basins that we will look at include Neva Creek, Mauze Gulch, and Niagara Creek. We will install 2 small (3 m tall) meteorological towers with instruments and one tall (10 m) meteorological tower in these basins. We will look at the surface energy balances of various vegetation types and determine the effect of the tundra fire that occurred in Niagara Creek several years ago. We will place small weirs in each of these small streams to gauge flows. These are ephemeral streams with flow only during snowmelt or heavy rains.