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Revised Final Report of:

THE SUBSURFACE GEOTHERMAL CLIMATE SIGNAL IN THE CONTEXT OF LSP/RADIOBRIGHTNESS MODEL-BASED ESTIMATES OF LAND-ATMOSPHERE

ENERGY AND MOISTURE FLUXES FOR REGIONS OF THE CIRCUMPOLAR ARCTIC (NASA Grant NAG5-11580)

A. W. England* and Henry Pollack** *Department of Atmospheric, Oceanic, and Space Sciences

*Department of Electrical Engineering and Computer Science **Department of Geological Sciences

The University of Michigan Ann Arbor, Michigan 48109-2122

I PROJECT SUMMARY Our objective is to relate the subsurface geothermal climate signal to energy and moisture

fluxes at the land-atmosphere interface of tussock tundra, and take the essential first steps toward enabling effective assimilation of AMSR and, eventually, SMOS satellite data in Soil-Vegetation-Atmosphere Transfer (SVAT) models of these fluxes. Our goal is to establish mutually consistent relationships among the subsurface geothermal climate signal, the continuing generation of that signal, and the satellite observations that will eventually enable near-continuous monitoring of these fluxes in tundra across the circumpolar Arctic.

Subsurface temperature fields in permafrost have been utilized extensively by the geothermal community to reconstruct the long-term trends of the temperature history experienced in the Arctic. The working hypothesis of the geothermal methodology is that temperature changes in the atmosphere and the solid Earth track each other. In geothermal analyses, the nature of this coupling is formulated simply as a time-dependent temperature boundary condition at the upper surface of a thermally conducting half-space. But the actual physical processes that achieve the coupling in the real world involve complex energy and moisture fluxes at the land-atmosphere interface over a large range of temporal and spatial scales. These processes are the focus of SVAT models like the Michigan Land Surface Process/Radiobrightness (LSP/R) model for prairie grassland which, when forced by weather and downwelling irradiance, has proven to reliably predict soil temperature and moisture profiles and consequent 19 GHz brightness. Reliable linkages among forcings, soil temperature and moisture profiles, and radiobrightness are essential if estimates of temperature and moisture state in arctic tundra are to be improved through assimilation of satellite radiobrightness data.

We are modifying and calibrating an LSP/R model for tussock tundra. Our objectives for this model are to investigate (1) the adequacy of such models to generate the downward propagating temperature signal utilized by geothermal scientists for climate reconstruction, (2) the constraints placed upon an acceptable range of energy and moisture fluxes by the geothermal climate signal, and (3) the model-imposed limitations upon surface flux estimates from anticipated assimilation of AMSR or SMOS radiobrightness data.

The Michigan prairie LSP/R model is a high physical fidelity, 1-dimensional, coupled heat and moisture transport model that predicts land-atmosphere fluxes of moisture and energy given

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boundary forcing by downwelling short- and long-wavelength radiation, air temperature and humidity, wind speed, and precipitation. Its predictions are based upon surface albedo and roughness, vegetation and snow cover, soil moisture and thermophysical properties, subsurface heat and mass transport mechanisms, and freezing and thawing processes. The model will be enhanced to include an embedded 3-dimensional tussock and an enhanced snow cover model. It will be calibrated with data from our year-long Radiobrightness Energy Balance Experiment, REBEX-3, conducted on the North Slope of Alaska during 1994-1995, and with data from an REBEX-10 that took place in the summer of 2004. This was a companion investigation of the NSF Project, Active Layer Thickness and Moisture Content of Arctic Tundra From SVAT/Radiobrightness Models and Assimilated 1.4 or 6.9 GHz Brightness. They shared the cost of the two-month field project near Toolik Lake, Alaska. Both required developing a land-surface model for arctic tundra but, otherwise, the projects were quite different. While much was accomplished in both of these projects, ultimately the land-surface model for the arctic tundra has not been completed. Field data are now available for validation of the model, an optimal technique has been developed to synthesize a circular AMSR footprint at a desired location having a slightly improved spatial resolution, and a snow model that we refer to as the Snow-Soil-Vegetation-Atmosphere Transfer (SSVAT) Model based upon a combination of an improved SNTHERM snow model and our prairie LSP Model has been developed. These advances are described in this report.

II GOALS, OBJECTIVES, AND TASKS Our goal was to establish mutually consistent relationships among the subsurface geothermal

climate signal, the continuing generation of that signal, and the satellite observations that will eventually enable near-continuous monitoring of land-atmosphere energy and moisture fluxes in tundra across the circumpolar Arctic. Our objectives are: (1) To examine the adequacy of our tundra LSP/R model for generation of the downward

propagating temperature signal utilized by geothermal scientists for climate reconstruction, (2) To quantify constraints placed upon land-atmosphere energy and moisture fluxes by the

geothermal climate signal, and (3) To identify the expected errors in estimated land-atmosphere energy and moisture fluxes

obtained from the tundra LSP/R model with assimilation of AMSR or simulated SMOS radiobrightness data.

III ACCOMPLISHMENTS Accomplishments during years -1 and -2 1) We completed an abbreviated inter-comparison between our Soil Vegetation Atmosphere

Transport (SVAT) model, the prairie Land Surface Process (LSP) model, and the Common Land Model (CLM). Overall, the comparison was favorable, but a few anomalies have warranted an extensive review of the LSP model involving Jasmeet Judge at the University of Florida and us. We anticipate that this review will result in a version v3.1 of the LSP model to be available in mid-spring 2004. This revised LSP model will become the basis for the new tundra model.

2) We have acquired two versions of SNTHERM. The first, from the Army Cold Regions Research and Engineering Laboratory (CRREL) (Jordan, 1991) is being examined to

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understand its physics and architecture. The second, a modified version of SNTHERM (Tribbeck, 2002), has been acquired and will be examined for potential advantages of its inclusion of vegetation. Neither of the models permits moisture exchange – either vapor or liquid water – between soil and snowpack. This is unrealistic and certainly does not take advantage of the coupled heat and moisture flux architecture of our soil SVAT model. We are currently developing an architecture that will permit us to place a version of SNTHERM on our tundra model.

We delayed integration of the snow model on tundra until the tundra model is complete. Unlike current snow models, we expect considerable interaction between the soil and snow models and this could not be designed without a nearly complete tundra model. The implication of this is that detailed land surface studies will be limited to the snow-free season for the duration of this grant. Annual averages may be obtained through a simple snow insulation model.

3) We have built a fully polarimetric 6.7 GHz radiometer for our new Truck-Mounted Radiometer System (TMRS3). TMRS3 now includes dual-polarized 1.4, 19, and 37 GHz radiometers, a polarimetric 6.7 GHz radiometer, a thermal infrared radiometer, and a video scene-grabber camera on the 35 ft boom of an aerial lift truck. TMRS3 with a dual-polarized version of our 6.7 GHz radiometer was deployed to Colorado as part of the NASA/Army Cold Lands Processes Experiment (CLPX) during winter and spring of 2003 near Fraser, Colorado. Our involvement with CLPX is referred to as the Radiobrightness Energy Balance Experiment 9, or REBEX-9. The 19 and 37 GHz radiometers produced excellent data. The h-pol channel of the 6.7 GHz radiometer produced excellent data but the v-pol data, while usable, were noisy. The problem was found to be a faulty cable/connector. The 1.4 GHz data were unusable because of a failed power supply. The TMRS3 radiometers have been repaired and are being tested in preparation for this grant’s field work, referred to as REBEX-10, near Toolik Lake, Alaska, during the late spring and early summer of 2004.

4) Henry Pollack has been in communication with researchers who have borehole data in permafrost. He has been assured that at least some of these data will be available to us.

5) Henry Pollack, Haley Gu, and Tony England spent a week at Toolik Lake, Alaska, selecting sites for REBEX-10 during the 2004 field season. We had pre-selected sites on the Imnaviat watershed but found these to be inaccessible to our truck. Through collaboration with Marc Stieglitz of Georgia Tech, we selected three new sites near the Toolik Lake Long-Term Ecological Research (LTER) site. The new sites are in tussock tundra, dry shrub, and wet sedge. Temperature, moisture, and heat flow sensors were buried at the tussock tundra and dry shrub sites. Temperature probes were buried in the wet sedge site. These sensors are now frozen into the permafrost and will provide the temperature and moisture record of the melting of the active layer during REBEX-10 this spring and summer.

6) The Truck Mounted Radiometer System (TMRS3) is being readied for the work near Toolik Lake, Alaska. Preparatory work on the truck is complete. The 19 and 37 GHz radiometers are ready, the 1.4 and 6.7 GHz radiometers are nearing final test. The Micro-Meteorology Station (MMS) has been reconfigured and is nearing final test. TMRS3 and MMS will begin their trip to the North Slope of Alaska on 15 April 2004.

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Accomplishments during year-3 • Completed the Radiobrightness Energy Balance Experiment (REBEX-10) at Toolik Lake

during spring and early summer 2004. • Completed the optimal footprint synthesis technique for AMSR data. • Completed development of a Snow-Soil-Vegetation-Atmosphere Transfer (SSVAT)

Model that is a combination of SNTHERM and our prairie Land Surface Process (LSP) Model. Soil Vegetation Atmospheric Transfer (SVAT) models have emerged as powerful tools for

prairie and agricultural hydrology because experimental data from a series of field campaigns in southern and mid-latitude prairie have enabled tests of schemes for modeling energy and moisture transport in prairie soils, and calibration of models of prairie terrains. Notable among the field campaigns have been the First ISLSCP Field Experiment (FIFE) in 1987 (e.g., Betts et al, 1996), Washita’92 (Jackson et al, 1995), and the Southern Great Plains Hydrology Experiments – SGP’97 – where our participation as our 5th Radiobrightness Energy Balance Experiment, REBEX-5, was reported by Judge et al (1999).

Our investigations have extended to terrains beyond those of southern and mid-latitude prairie. REBEX-1 was a 7 month experiment in northern prairie grassland near Sioux Falls, South Dakota, during fall and winter of 1992-1993 (Galantowicz, 1995; Galantowicz and England, 1997). REBEX-3 was a 12 month experiment in tussock tundra near Toolik Lake, Alaska, during 1994-1995 (Kim and England, 1998; Kim, 1999, Kim and England, 2002). REBEX-4 was a summer study in northern prairie near Sioux Falls in 1996 (Judge et al, 1999; Judge et al, 2001). REBEX-7 and –8 were summer investigations in agricultural terrain (corn) near Ann Arbor, Michigan (Hornbuckle and England, 2002 a & b). REBEX-9, during late winter and early spring of 2003 near Fraser, CO, was our contribution to the Cold Lands Processes Experiment, CLPX.

REBEX-3 was a first step toward developing a high physical fidelity SVAT model for arctic terrains. Referred to as the Land Surface Process/Radiobrightness (LSP/R) Model, our objective was to adapt a successful prairie LSP/R model to tussock tundra for the SSM/I frequencies of 19, 37, and 85 GHz. Key findings from that experiment were (Kim, 1999):

• Data from the 19, 37, and 85 GHz REBEX radiometers, or from equivalent SSM/I channels, clearly delineate the onset of spring thawing and fall freezing of the permafrost active layer.

• Tundra in the vicinity of the REBEX-3 site was sufficiently homogeneous over scales of meters to tens of kilometers that our 19 GHz and 37 GHz observations with footprints of 3 m closely matched the 19 GHz and 37 GHz SSM/I observations with footprints of 50 km and 25 km, respectively (Figure 6) (Kim and England, 2002).

• Vegetation canopies on tussocks at the REBEX-3 site were sufficiently absorbing at 19 GHz, the most penetrating of the SSM/I channels, to cause 19 GHz brightness to become a non-linear average of the spatial distribution of emission from soil moisture within the footprint (Liou et al, 1998). This and the limited sensitivity of 19 GHz brightness to soil moisture render SSM/I data relatively useless as a quantitative measure of soil moisture in the Arctic.

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• LSP/R models that worked so well for prairie could not be adapted effectively to tussock tundra. While we could force tantalizing fits between the observations and the model, the underlying biophysics, as expressed in the spatial structure and constitutive properties of soil and vegetation, were not realistic. Because the biophysics were inappropriate, it is unlikely that extrapolations either from the 19 GHz calibration frequency to 1.4 GHz, or from the REBEX-3 site to other arctic terrains would be reliable.

Field radiometers for calibrating these models Field systems needed for SVAT/Radiobrightness calibration experiments include microwave

radiometers at the appropriate frequencies, polarizations, and incidence angles; instruments to record the radiance and meteorological forcings; and instruments to record the temperature and moisture response of soil and vegetation. We have grouped the radiometers and meteorological sensors into what has now become a Truck Mounted Radiometer System (TMRS3) (Figure 1) and Micrometeorological System (MMS) (Figure 2). TMRS3 consists of dual-polarized 1.4, 6.7, 19, and 37 GHz radiometers, a Thermal Infrared Radiometer (TIR), and a video scene grabber mounted on the 12 m hydraulic arm of a NorSTAR aerial lift diesel truck. The 6.7 GHz radiometer was developed under this investigation. The truck has a 7.5 kW diesel generator for autonomous operation and an electronic repair facility with diesel heating and electric air conditioning. The MMS includes a 10 m tower with an adjustable height trolley; 2 m and 10 wind speed, air temperature, and humidity probes; a Bowen ratio instrument; a 4-component radiometer; multiple soil moisture and temperature probes; multiple canopy or snow temperature probes; and a data logger (Hornbuckle et al, 2000). TMRS3 and MMS were deployed to the Toolik Lake area from late April through the end of June, 2004, in support of this experiment. We refer to the field experiment as REBEX-10.

Figure 1. TMRS3 deployed at the shrub site near Toolik Lake, Alaska, in 2004 during REBEX-10.

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Figure 2. MMS in a cornfield south of Ann Arbor, MI. The picture was taken during REBEX-7.

Research grade microwave radiometers are unique to their purpose and prohibitively expensive to obtain commercially. We build our own and provide radiometers for other research groups at the recurring cost of their fabrication. The TMRS3 19 and 37 GHz radiometers were repackaged from TMRS2 to incorporate cool-bias temperature control and FPGA-based internal intelligence. The 1.4 and 6.7 GHz radiometers were new instruments for REBEX-9 and REBEX-10, respectively. They were based upon the innovative design of the NSF-funded STAR-Light receivers. We chose 6.7 GHz rather than AMSR’s 6.9 GHz because there were cost advantages to using 6.7 GHz components. The difference of 200 MHz does not affect sensitivity to soil moisture.

Validation of the Concept in the Arctic Validation of the SVAT/Radiobrightness model/assimilation–based approach to estimating

active layer thickness and water content serves four purposes. It (1) tests our 1st hypothesis that the tundra model and assimilated 1.4 or 6.9 GHz brightness observations will yield reliable estimates of plot-scale active layer thickness and water content, (2) enables generation of a synthesized data set for a limited test of our 2nd hypothesis that the approach works at the scale of a satellite footprint, (3) provides some data on the temporal and spatial variability of 1.4 and 6.7 GHz brightness in the Arctic, and (4), because these will be the first plot-scale 1.4 and 6.7 GHz brightness observations in arctic tundra, generates an experience base for future investigations.

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The REBEX-10 Field Experiment

Figure 3. Location of REBEX-10, plot-scale sites.

An enabling achievement of this investigation was successful completion of the REBEX-10 experiment. The experiment was conducted near Toolik Lake, as shown in Figure 3, and focused upon what we believe are 3 canonical terrain types from the perspective of microwave radiometry: Tussock tundra (Figure 4a), dry heath or shrub (Figure 4b), and wet sedge (Figure 4c). We had chosen the specific plot-scale study areas and buried TDR soil moisture probes, and temperature and heat flux sensors in the active layer during a visit to the area in August, 2003. Our observations began before snowmelt in April and extended through June.

Plot-scale sites

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Figure 4a. Plot-scale tussock tundra site. MMS instruments here included: Air temperature, relative humidity, wind speed and direction, net radiation, Bowen ratio, soil temperature, soil moisture, soil heat flux, vegetation leaf temperature, water temperature, and downwelling and upwelling shortwave radiation. Figure 4b. Plot-scale shrub site. MMS instruments here included: Soil temperature, soil moisture, and heat flux. This site was within 100 m of the tussock tundra site so that weather and radiant energy observations at the tussock tundra site applied here as well. Figure 4c. Plot-scale wet sedge. MMS instruments here included: Soil temperature and water temperature. This site was within 0.5 km of the tussock tundra site so that weather and radiant energy observations at the tussock tundra site applied here as well.

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V- and H-polarized brightness data at 1.4, 6.7, 19, and 37 GHz were collected at the tussock tundra and shrub sites. The wet sedge site lay beyond a damaged area of the access road that could have easily damaged our field truck. Because the wet sedge site looked very much like standing water from the perspective of H-polarized microwave radiometry at the frequencies of interest, H-polarized satellite data are expected to be of greatest value, we knew water temperature, and the surface of the standing water was typically smooth relative to the microwave wavelengths of interest, we will be able to predict the microwave brightness of the wet sedge using simple Fresnel theory. The combination of risk to the equipment and an anticipate low value of the data justified removing the wet sedge site from the observing rotation. Radio Frequency Interference (RFI) from defense radars on the North Slope of Alaska played havoc with our 1.4 GHz data records. The radar introduced intermittent pulse signals with a repetition rate of about once per second that were orders of magnitude greater than the thermal signal we were observing. In theory, we could observe between the pulses, but we had no way of timing the observations to avoid the pulses. There are RFI mitigation techniques that will allow meaningful 1.4 GHz brightness observations, but the chosen technique must be built into the control logic of the radiometer. This will be a condition of future 1.4 GHz observations. Figure 5 is an example of radiobrightness data collected at the tussock tundra site. Diurnal V- and H-polarized, 6.7, 19, and 37 GHz brightness temperatures and Thermal Infrared Radiant (TIR) temperatures exhibit decreasing brightness with decreasing frequency, a result of liquid water in and around the tussocks. We also observe diminished amplitude with decreasing frequency, a result of emission at depth within the tussock where the diurnal pulse is beginning to be subdued.

Figure 5. Diurnal temperatures at a 350 incidence angle for 6.7, 19. and 37 GHz brightness and for TIR. These are REBEX-10 data for tussock tundra

A comparison between REBEX-10 and AMSR Observations

The combination of REBEX-10 and AMSR data allow us to extend our plot-scale findings to satellite resolution-scale. Time-series comparisons of these data require synthesizing AMSR footprints centered on the REBEX-10 site. AMSR-E is in a Sun- synchronous low Earth orbit and scans along arcs of nadir-centered cones whose half angle is 550. The Instantaneous Field of

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View (IFOV), or footprint on the ground, along one of these scans is nearly elliptical with an aspect ratio of 1.66 and an orientation that varies by ~700 along a single scan. AMSR data at the lower frequencies are over-sampled permitting a Backus-Gilbert Equal Area Scaling–Grid (EASE-Grid) synthesis from elliptical swath footprints (Figure 6a), which move and rotate spatially from pass-to-pass, to circular synthetic footprints (Figure 6b), which are spatially stable and centered on the REBEX-10 site from pass-to-pass (Gu and England, 2004). These synthesized footprints are 45 km in diameter, representing a 15% improvement in spatial resolution relative to the swath data.

Figures 6a (left) and 6b (right) show the 6.9 GHz, H-pol footprint and the EASE-Grid synthetic footprint, respectively. Red rings delineate the 3 dB patterns in both figures. The 3 dB swath pattern in 9a is elliptical, and moves spatially and changes orientation from pass-to-pass. The 3 dB synthesized pattern in 9b is circular and stationary from pass-to-pass. Side-lobes generated in the synthesis pattern are ≥20 dB below the beam maximum and contribute negligibly to synthetic scene brightness.

Figure 7. 6.9 GHz AMSR data synthesized to be centered on the REBEX-10 field site. The plot also shows rain events during the period.

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Figure 7 shows that REBEX-10 V-pol 37 and 19 GHz plot-scale data for tussock tundra compare well with the corresponding AMSR satellite resolution-scale data. The V-pol 6.7 GHz plot-scale data are ~4 Kelvin warmer than the V-pol 6.9 GHz AMSR data (the difference between 6.7 and 6.9 GHz cannot explain this brightness difference). H-polarized 37, 19, and 6.7 GHz plot-scale data are ~3, ~4, and ~11 Kelvin warmer than their corresponding AMSR data. The conclusions from REBEX-3 that 19 and 37 GHz scene brightness temperatures are the same at plot- and satellite resolution-scales are not valid for the H-pol data at this site. The REBEX-10 differences at 6.9 GHz suggest significant sub-pixel variability. The synthetic AMSR footprint at the REBEX-10 site includes tussock tundra, dry heath, and wet sedge. Wet sedge looks sufficiently like standing water to a microwave radiometer that we chose to observe only tussock tundra and dry heath at the plot-scale. We believe that area-weighted combinations of tussock tundra, dry heath, and standing water will explain the AMSR observations. We are currently testing this hypothesis. If it proves true, there is an optimal 3-part disaggregation of AMSR observations that corresponds to the 3 terrain types.

Figure 8. A comparison of AMSR data with plot-scale data for tussock tundra.

Figure 8, a plot of 6.9 GHz AMSR data synthesized to be centered on the REBEX-10 field site, is included to show sensitivity to recent rainfall events. For example, note the ~10 Kelvins decrease in brightness after the event on day 168. We observed an even greater sensitivity of rainfall events in the site radiobrightness data.

Finding 1 – 6.9 GHz AMSR data is sensitive to moisture in the active layer. This suggests that current satellite data could be providing useful hydrologic monitoring of the pan-Arctic if the necessary models and techniques were in place.

Finding 2 – 6.9 GHz plot-scale data for tussock tundra and shrub are sensitive to moisture in the active layer. These observations are consistent with the satellite observation being composed of an aggregate of emission from tussock tundra, shrub, and standing water terrains.

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Finding 3 – The V-pol 19 and V- and H-pol 37 GHz data appear the same at plot- and satellite-scales. This is consistent with REBEX-3 observations that these frequencies and polarizations are primarily sensitive to the vegetation.

Finding 4 – The H-pol 19 and V- and H-pol 6.7 GHz data differ between plot- and satellite-scales. The 19 GHz conclusion differs from a conclusion of REBEX-3. These observations are consistent with the lower frequencies being sensitive to sub-pixel variations in water storage in the active layer.

Finding 5 – The satellite observations of the Alaskan North Slope are likely to be explained by a area-weighted aggregate of tussock tundra, shrub, and standing water. The hypothesis is being tested. If tests prove it to be true, the combination of SVAT models for tussock tundra and shrub will permit an optimum 2-part disaggregation of the satellite data.

Finding 6 – To be useful, 1.4 GHz observations must employ a mitigation technique that excludes pulse RFI from defense radars in the Arctic. In addition to the Findings, this investigation provides a dataset that will allow validation of

SVAT models for tussock tundra and shrub. These data will be archived as part of Ms. Haley Gu’s dissertation under a new digital dissertation opportunity. We had planned to complete these SVAT models as part of this investigation. The need to develop a new model for the thermal conductivity and moisture retention of organic soils (Gu et al, 2006), and the opportunity to develop a scheme for synthesizing a circular footprints at improved spatial resolution forced us to delay development of the SVAT models until the next project. A proposal has been submitted to NASA to use data from this investigation to complete the two SVAT models.

A novel fully polarimetric 6.7 GHz radiometer has been developed as the University’s cost sharing contribution to this project. A version of this same radiometer has also been built, tested, and delivered to the University of Florida (UF). The cost to UF was only the recurring cost of duplicating our instrument. The UF radiometer is planned for use in NASA-related investigations of agricultural land-surface hydrology. These radiometers allow ground calibration of models that will assimilate low frequency brightness data from the new AMSR instruments. They are a novel design in using the Direct Sampling Digital Radiometer (DSDR) receiver architecture that we developed for STAR-Light, a 1.4 GHz aperture synthesis radiometer we developing for the NSF. In the case of the 6.7 GHz radiometers, 6.7 GHz brightness is down-converted to 1.4 GHz for the DSDR receivers. The result is a compact receiver that takes maximum advantage of the $1.38M NSF investment in STAR-Light.

IV BROADER IMPACTS The proposed project spanned two departments of the College of Engineering at the

University of Michigan, the Departments of Atmospheric, Oceanic, and Space Sciences and the Department of Electrical Engineering and Computer Science. It provided several undergraduate environmental scientists and electrical engineers opportunities to work in a team environment on an exciting environmental project that would have significant impact.

We participated in the NSF OPP TREC Program where a middle-school science teacher joined us for two months at the Toolik Lake LTER. She was able to broadcast live video of our work near Toolik Lake to her class in Wisconsin and to other classes participating in the TREC Project.

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Two female graduate students participated in the Project. Ms. Haley Gu was lead on the REBEX-10 field experiment, developed the optimal footprint synthesis technique for AMSR data, and will complete test of the canonical terrain type hypothesis as part of her Ph.D. dissertation. Ms. Hanh Pham developed and calibrated the fully-polarimetric, 6.7 GHz radiometer for REBEX-9 and REBEX-10, and participated in the REBEX-10 field experiment. One female undergraduate participated in the Project. Ms. Nupur Srivastava helped us develop the new TIR and video sensors on TMRS3.

The PI also gave frequent talks at the pre-college level about his experiences in science and as an astronaut. The objective was to motivate student interest in the STEM fields.

V PUBLICATIONS TO WHICH THIS INVESTIGATION CONTRIBUTED (ADDITIONAL JOURNAL ARTICLES ARE IN PREPARATION)

Journal articles Gu, H., T-Y Lin, J. Judge, A.W. England, and J.J. Casanova, Estimating soil thermal

conductivity and water retention from readily available soil properties, submitted to Water Resources Res, February 2006.

Judge, J., L.M. Abriola, and A.W. England, Development and numerical validation of a summertime Land Surface Process and Radiobrightness model, Advances in Water Resources, 26/7, pp 733-746, 2003.

Judge, J., A.W. England, J.R. Metcalfe, D. McNichol, and B.E. Goodison, Calibration of a summertime Land Surface Process and Radiobrightness (LSP/R) model for bare and vegetated soils, submitted to J. Water Resources Res., July, 2002.

Kim, E.J., and A.W. England, A Year-Long Comparison of Plot-Scale and Satellite Footprint-Scale 19 and 37 GHz Brightness of the Alaskan North Slope, J. Geophys. Res. Vol. 108, No. D13, 4388, 10.1029/2002JD002393, 10 July 2003.

Lin, X., Smerdon, J., England, A. W., Pollack, H. N., 2003. A model study of the effects of climatic changes on ground temperatures, Journal of Geophysical Research, 10.1029/2002JD002878, 12 pp.

Pham, H., E.J. Kim, and A.W. England, An analytical calibration approach for polarimetric radiometers, IEEE Trans Geosci. Remote Sensing, 43, pp.2443-2451, 2005.

Pollack, H.N., Demezhko, D.Yu., Duchkov, A.D., Golovanova, I.V., Huang, S., Shchapov, V.A., Smerdon, J., 2003. Surface temperature trends in Russia over the past five centuries reconstructed from borehole temperatures, Journal of Geophysical Research doi:10.1029/2002JB002154, 12 pp.

Pollack, H.N. and Smerdon, J., 2004. Borehole climate reconstructions: spatial structure and hemispheric averages, Journal of Geophysical Research 109, D11106, doi:10.1029/2003JD004163, 9 pp.

Pollack, H.N., Smerdon, J. van Keken, P., 2005. Variable seasonal coupling between air and ground temperatures: A simple representation in terms of subsurface thermal diffusivity, Geophysical Research Letters, 32, L15405, doi:10.1029/2005GL023869, 4 pp.

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Smerdon, J.E., Pollack, H.N., Cermak, V., Enz, J., Kresl, M., Safanda, J., Wehmiller, J., 2006. Daily, seasonal and annual relationships between air and subsurface temperatures, Journal of Geophysical Research (doi:10.1029/2004JD005578).

Smerdon, J., Pollack, H. N., Cermak, V., Enz, J. W., Kresl, M., Safanda, J., Wehmiller, J. F., 2004. Air-ground temperature coupling and subsurface propagation of annual temperature signals, Journal of Geophysical Research 109, D21107, doi:10.1029/2004JD005056, 10 pp.

Smerdon, J., Pollack, H. N., Enz, J., Lewis, M., 2003. Conduction-dominated heat transport of the annual temperature signal in soil, Journal of Geophysical Research doi:10.1029/2002JB002351, 6 pp.

Symposia – Refereed Proceedings Chung, Y-C, and A.W. England, A coupled Soil-Snow-Atmosphere Transfer Model, Proc.

IGARSS’05, Seoul, Korea, 25-29 July, 2005. Chung, Y.-C., A.W. England, R.D. De Roo, and E. Weininger, Effects of Vegetation and of Heat

and Vapor Fluxes from Soil on Snowpack Evolution and Radiobrightness Observed during the Cold Lands Processes Experiment in Colorado, Proc. IGARSS’06, Denver, CO, July 31 – August 4, 2006.

De Roo, R.D., A. Chang, and A.W. England, Radiobrightness at 6.7GHz, 19GHz and 37GHz from Mature Evergreen Trees, Proc. IGARSS’06, Denver, CO, July 31 – August 4, 2006.

De Roo, R.D, A.W. England, Haoyu Gu, Hanh Pham, and H. Elsaadi, Ground-based Radiobrightness Observations of the Active Layer Growth on the North Slope near Toolik Lake, Alaska, Proc. IGARSS’06, Denver, CO, July 31 – August 4, 2006.

England, A.W., X. Lin, J. Smerdon, and H.N. Pollack, The influence of soil moisture upon the geothermal climate signal, Proc. IGARSS’03, Toulouse, France, July 21-25, 2003 [invited].

England, A.W., and R.D. DeRoo, STAR-Light: An enabling technology for modeling arctic land surface hydrology, Proc. IGARSS’02, Toronto, Canada, June 24-28, 2002. [invited]

Gu, H., and A.W. England. Backus-Gilbert resampling of AMSR data to synthesize circular footprints with potentially improved spatial resolution, Proc. IGARSS’04, Anchorage, Alaska, September 20-24, 2004.

Kim, E.J., and A.W. England, Passive microwave remote sensing of land surface conditions in arctic tundra regions, Proc. of 6th Circumpolar Symposium on Remote Sensing of Polar Environments, Yellowknife, NWT, Canada, June 12-14, 2000.

Kim, E.J., and A.W. England, Diurnal and Seasonal Cold Lands Signatures in SSM/I-scale Microwave Radiometry of the North Slope of Alaska, Proc. IGARSS’01, Sidney Australia, July 9-13, 2001.

Kim, E.J., M. Tedesco, A.W. England, R.D. DeRoo, and H. Gu, Local scale radiobrightness modeling during Intensive Observing Period-4 of the Cold Land Processes Experiment-1, Proc. IGARSS’04, Anchorage, Alaska, September 20-24, 2004.

O’Neill, P., A. Hsu, E. Kim, C. Peters-Lidard, X. Lin, and A.W. England, Performance comparison of a point-scale LSP model and the NOAH Distributed SVAT model for soil moisture estimation using microwave remote sensing, Proc. IGARSS’01, Sidney, Australia, July 9-13, 2001.

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Pham, H., A.W. England, V. Solo, E.J. Kim, Experimental and modeling investigation of microwave radiometer noise statistics for Earth remote sensing, Proc. IGARSS’05, Seoul, Korea, 25-29 July, 2005.

Pham, H., R. DeRoo, A.W. England, L. van Nieuwstadt, and J. Glettler, A C-Band radiometer based on STAR-Light receivers: design approach, implementation, and performance evaluation, Proc. IGARSS’03, Toulouse, France, July 21-25, 2003.

SYMPOSIA - Abstracts Only Chung, Y-C, and A.W. England, The Influence of Snow-Soil Moisture Flux and Snow Pack

Metamorphism in Late Winter and Early Spring, Eastern Snow Conference, Newark, Delaware, June 7-9, 2006 (best paper award).

England, A.W., STAR-Light, an enabling technology for arctic land surface hydrology, Earth System Science Institute Colloquium, University of Reading, England, July 5, 2001, [invited].

England, A.W., Progress with the Land Surface Process/Radiobrightness Model, Specialist Meeting on Microwave Remote Sensing, Boulder, Colorado, November 5-9, 2001, [invited].

England, A.W., and R. DeRoo, STAR-Light: Enabling a new vision for land surface hydrology in the Arctic, AGU Fall Meeting, San Francisco, CA, December 10-14, 2001.

De Roo, R., A.W. England, C. Ruf, L. Van Nieuwstadt, P. Hansen, T. Rashid, J. Harvey, R. Miller, and D. Boprie, STAR-Light: An airborne L-band synthetic thinned aperture direct sampling digital radiometer for soil moisture monitoring in the Arctic, 3rd SMOS Cal-Val Workshop, Oberfaffenhofen, Germany, December 10-12, 2001.

England, A.W., STAR-Light, a enabling approach to land surface hydrology in the Arctic, Space Science Seminar, University of Michigan, January 18, 2002.

England, A.W., Remote Sensing Hydrology: a merging of science and engineering, Saturday Seminars, University of Michigan, May 11, 2002.

England, A.W., STAR-Light: An enabling technology for arctic land surface hydrology, seminar at NSF, Washington, DC, May 20, 2002 [invited].

England, A.W., Experiment plan for TMRS3 during CLPX, CLPX Workshop, Army Cold Regions Research and Engineering Laboratory, Dartmouth, NH, June 3-4, 2002 [invited].

England, A.W., and R.D. DeRoo, STAR-Light: An enabling technology for modeling arctic land surface hydrology, (invited) IGARSS’02, Toronto, Canada, June 24-28, 2002.

England, A.W., The impact of remote sensing upon global hydrology, U. of Michigan Society of Fellows Lecture, November 11, 2002 [invited].

England, A.W., and R. DeRoo, STAR-Light: An enabling technology for arctic land surface hydrology, NSF Arctic Systems Science All Hands Workshop, Seattle, WA, February 20-22, 2002.

England, A.W., R. DeRoo, H. Pham, and H. Gu, Truck-Mounted Radiometers at CLPX, AGU Fall Meeting, San Francisco, CA, Dec 8-12, 2003 [Invited].

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England, A.W., and Xiaohua Lin, The contribution of land atmosphere moisture flux to the geothermal climate signal, Atmospheric Science Seminar, University of Michigan, March 12, 2002.

Gu, H., and A.W. England, A Backus-Gilbert resampling scheme for AMSR-E Data that offers improved footprint shape and spatial resolution, Proc. IGARSS’04, Anchorage, Alaska, September 20-24, 2004.

Gu, H., H. Pham, Y.C. Chung, and A.W. England, Model-Based Monitoring of Pan-Arctic Tundra, The Arctic Forum 2003, ARCUS, Arlington, VA, April 28-29, 2003.

Gu, H., H. Pham, Y-C Chung, R.D. DeRoo, and A.W. England, Model-Based Monitoring of Pan-Arctic Tundra, ARCSS All Hands Meeting, Seattle, WA, June 1-3, 2005.

Gu, Haley, Tzu-yun Lin, Jasmeet Judge, and A.W. England, A Soil Thermal Conductivity Model Based upon Component Conductivities and Fractions for use in Soil-Vegetation-Atmosphere Transfer Models, AGU Fall Meeting, San Francisco, CA, Dec 5-9, 2005.

Kim, E., A.W. England, and J. Judge, Scaling Issues between plot and satellite radiobrightness observations of arctic tundra, AGU Fall Meeting, San Francisco, CA, December 15-19, 2000.

Lin, X., A.W. England, J. Smerdon, and H.N. Pollack, A modified SVAT model that links the geothermal climate signal to land-surface processes, AGU Fall Meeting, San Francisco, CA, December 10-14, 2001.

Lin, X., A.W. England, J.E. Smerdon, and H.N. Pollack, Connecting land-surface processes with the geothermal climate signal using a modified SVAT model: the precipitation example, AGU Spring Meeting, Washington, D.C., May 28-31, 2002.

Pham, H., R. D. De Roo, and A.W. England, Simple calibration scheme for a fully polarimetric correlating radiometer, MicroRad’06, San Juan, Puerto Rico, Feb 28-Mar 3, 2006.

VI REFERENCES Betts, A., S. Hong, and H. Pan, 1996. Comparison of NCEP/NCAR reanalysis with 1987 FIFE

data, Monthly Weather Review, 124(3): 362-383. Bonan, G., 1996. A Land Surface Model (LSM Version 1.0) for ecological, hydrological, and

atmospheric studies: Technical description and user’s guide, Tech. Rep. NCAR/TN-417+STR, Climate and Global Dynamics Division, NCAR.

Dickinson, R., A. Henderson-Sellers, and P. Kennedy, 1993. Biosphere-atmosphere transfer scheme (BATS) version 1e as coupled to the NCAR Community Climate Model, Tech. Rep. NCAR/TN-387+STR, Climate and Global Dynamics Division, NCAR.

Dickinson, R., A. Henderson-Sellers, P. Kennedy, and M. Wilson, 1986. Biosphere-atmosphere transfer scheme (BATS) for the NCAR Community Climate Model, Tech. Rep. NCAR/TN-275+STP, Atmospheric Analysis and Prediction Division, NCAR.

England, A.W., 1990. Radiobrightness of diurnally heated, freezing soil, IEEE Trans.Geosci. Remote Sensing, 28, pp.464-476.

England, A.W., and Galantowicz, J.F. (1994). A volume emission model for the radiobrightness of prairie grass, Proc. of IGARSS'94, Pasadena, CA, August 8-12.

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England, A. and J.F. Galantowicz, 1995. Observed and modeled radiobrightness of prairie grass in early fall,” Proc. of IGARSS’95, IEEE GRSS, Florence, Italy, July 10-12.

Gu, H., and A.W. England, 2004. Backus-Gilbert resampling of AMSR data to synthesize circular footprints with potentially improved spatial resolution, Proc. IGARSS’04, Anchorage, Alaska, September 20-24.

Gu, H., T-Y Lin, J. Judge, A.W. England, and J.J. Casanova, Estimating soil thermal conductivity and water retention from readily available soil properties, submitted to Water Resources Res, February 2006.

Jordan, R., 1991. A one-dimensional temperature model for a snow cover: Technical documentation for SNTHERM, CRREL Special Report 91-16, Cold Regions Research and Engineering Laboratory, Hanover, NH.

Judge, J., 1999. Land Surface Process and Radiobrightness Modeling of the Great Plains. Ph.D. Dissertation, University of Michigan, 213 pages.

Judge, J., L.M. Abriola, and A.W. England, 2003. Development and numerical validation of a summertime Land Surface Process and Radiobrightness model, Advances in Water Resources, 26/7, pp 733-746.

Judge, J., A. England, C.L.W. Crosson, B. Hornbuckle, D. Boprie, E. Kim, and Y. Liou, 1999. A growing season Land-Surface Process/Radiobrightness model for wheat-stubble in the Southern Great Plains. IEEE Trans. Geosci. Remote Sensing, 37, 2152-2158.

Judge, J., J.F. Galantowicz, and A.W. England, 2001, A comparison of ground-based and satellite-borne microwave radiometric observations in the Great Plains, IEEE Trans. Geosci. Remote Sensing, 39, pp. 1686-1696.

Kim, E.J., 1999. Remote Sensing of Land Surface Conditions in Arctic Tundra Regions for Climatological Applications Using Microwave Radiometry, Ph.D. Dissertation, University of Michigan, 172 pages.

Kim, E.J., and A.W. England, 1998. Land surface process modeling and passive microwave remote sensing of arctic tundra regions, Proc of IGARSS’98, Seattle, WA, July 6-10.

Kim, E.J., and A.W. England, 2003. A Year-Long Comparison of Plot-Scale and Satellite Footprint-Scale 19 and 37 GHz Brightness of the Alaskan North Slope, J. Geophys. Res. Vol. 108, No. D13, 4388, 10.1029/2002JD002393.

Liang, X., D. Lettenmaier, E. Wood, and S. Burges, 1994. A simple hydrologically based model of land surface water and energy fluxes for general circulation models, J. Geophys. Res., 99, pp. 14415-14428.

Liang, X., D. Lettenmaier, E. Wood, and S. Burges, 1996. One-dimensional statistical dynamical representation subgrid spatial variability of precipitation in the 2-layer variable infiltration capacity model, J. Geophys. Res., 101, pp. 21403-21422.

Liou, Y.A., and England, A.W. (1996), Annual temperature and radiobrightness signatures for bare soils, IEEE Trans. Geosci. and Remote Sensing, 34, 981-990.

Liou, Y.A., and A.W. England, 1998a. A land surface process/radiobrightness model with coupled heat and moisture transport in soil, IEEE Trans. Geosci. Remote Sensing, 36, pp. 273-286.

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Liou, Y.A., E.J. Kim, and A.W. England, 1998b. Radiobrightness of prairie soil and grassland during dry-down simulations, Radio Science, 33, pp. 259-265.

Liou, Y.-A., J. F. Galantowicz, and A. W. England, 1999. A Land Surface Process/ Radiobrightness Model with Coupled Heat and Moisture Transport for Prairie Grassland, IEEE Trans. Geosci. Remote Sensing, 37, pp. 1848-1859.

Sellers, P., Y. Mintz, Y. Sud, and A. Dalcher, 1986. A simple biosphere model SiB for use within general circulation models, J. Atmos. Sc., 43, pp. 505-531.

Trenberth, K.E., 1995. Climate System Modeling, Cambridge Press, 788 pages. Tribbeck, M.J., 2002. Modelling the effect of vegetation on the seasonal snow cover, Ph.D.

dissertation, Environmental Systems Science Centre, University of Reading, U.K.