Surface Soil Moisture & Groundwater Monitoring, Estimations, Variations, & Retrievals Discussions Questions
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The following discussions questions were used to facilitate the in-class discussion on Surface Soil Moisture Monitoring. The discussion was facilitated by Christina Geller and Jenkins Macedo on November 4, 2013.
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Surface Soil Moisture & Groundwater Monitoring, Estimations, Variations, & Retrievals Discussions Questions
- 1. Jenkins Macedo Christina Geller GEOG392 November 4, 2013 Discussion Questions: Monitoring of Surface and Groundwater Resources Choi et al., 2008 1. On page 2, the authors explain the problems with the three measurement systems for calculating soil moisture. What problems do you think are more concerning than others? What problems will carry over in a mixed analysis scheme? 2. On page 4, Choi et al. explain how the vegetation temperature and the surface temperature are assumed to be the same in the calculation of soil moisture by AMSRE. Do you agree with this assumption? Why or why not? 3. Given what you learned about the Common Land Model during our discussion of surface albedo from our discussion of surface albedo and the results from this study, would you push for further utilization of CLM? Why or why not? 4. The authors suggest developing a better understanding of the impact of slope and elevation on soil moisture estimations. Given what you know already, what impacts would you expect to see? 5. Table 3 on page 8 shows how the correlation coefficient (R2) declined when CLM AMSRE are used together yet the Root Mean Squared Error (RMSE) typically improved. Why do you think that is? Reichle et al., 2007 1. On page 1, the authors’ claimed that “satellite retrievals alone; however, are not sufficient for weather and climate forecast initialization because of gaps in spatial and temporal coverage and because model variables, such as deeper root zone soil moisture cannot be observed from space.” Given what we’ve have learned thus far, do you agree or disagree? What are the associated complexities of using meteorological forcing inputs from land surface model with satellitedriven soil moisture retrievals? 2. On page 2, it is stated that “via the land surface model, the system propagates the surface information the satellite into deeper soil and thereby provides improved estimates of root zone soil moisture.” What do you would be some of the setbacks with this approach? How would this approach be applicable in ecosystems with dense forest canopy and those with lesser canopy coverage?
- 2. 3. On page 2, the authors noted that rescaling satellite data prior to the assimilation process by matching the satellite data’s cumulative distribution function to the model’s climatology builds heavily on the anomaly time series, which is the basis for forecast initialization, instead of relying on the mean square error measures, which cannot be validated. Are four years of data sufficient ground to make this assertion about the validation process? Do you agree with their claim? Why or why not? 4. On page 2 in the second column in the 3rd paragraph under satellite retrievals, the authors described that the AMSRE satellite retrievals of surface soil moisture data used are from NASA Level2B AMSRE “AE_Land” product, which includes measurements of surface soil moisture, a vegetation/roughness correction, and “quality control variables.” What are the quality control variables? Do you think the authors’ could have deliberated on these variables a little more? 5. What are your critiques about the structure of the paper and the way in which results were presented? Who do you think are the targeted audience for such a paper apart from just the fact that it was published in the Journal of Geophysical Research? Swenson et al., 2008 1. Who do you think are the targeted audience of this paper and why? Was the subject matter adequately assessed? 2. Given the scope of the data used, do you think the authors did a great job explaining the data, methods, results, and purpose of the research adequately? 3. On page 2 in the second column, the authors claim that “the methods described account for deeper soil moisture is applied to the region of the Southern Great Plains of the U.S., but is applicable to other observational data sets, whether in situ or remotely sensed data.” Do you agree with this claim given the challenges in many developing countries where in situ and remotely sensed data acquisition is not only a logistical problem? 4. What are some of the complexities in monitoring and assessing groundwater resources; given the potential for groundwater to extend beyond geographic boundaries of states and regions? Syed et al., 2008 1. Who do you think are the targeted audience of this paper? Why? 2. What are some of the major challenges/advantages of this approach? 3. Do you agree with the authors’ claim that with longer time series, GRACE will contribute to improved the understanding of how terrestrial water storage respond to climate change variability? 4. Are the results from their analyses compelling enough to warrant the advancement of this science? 5. If you were to make a constructive input to the methodology in the advancement of this
- 3. approach, what would your recommendation be and why? de Jeu et al., 2008 1. On page 408, the authors explain that “a data mask was developed on the AMSRE data products to eliminate those data cells where data values were either meaningless due to frozen soil conditions, snow cover or excessive vegetation”. What biases do you see arising from the use of this data mask? 2. The AMSRE developed by NSIDC had a correlation coefficient of 0.01 in the France study area and 0.00 for Spain. Because of this, the authors decided to exclude AMSRE (NSIDC) from their comparison analysis. What do you think the authors might have missed contributing to the field by excluding this soil moisture product? 3. This study pointed out a strong similarity between both products in sparse to moderate vegetated regions with an average correlation coefficient of 0.83. Given this similarity, do you see a benefit of further developing one product or using one product over the other? 4. Do you agree with the authors’ suggestion of combining the two products? 5. The authors explain the reasons why low correlations may be found in densely vegetated areas and deserts. Are there other reasons you think are missing from their explanation? General Questions 1. If remote sensing of soil moisture is primarily capable of representing variation in near surface wetness (e.g. upper 5 to 10 cm of soil) and not wetness deeper in the rooting zone, what does this mean for the processes that can be wellpresented by this product? 2. Does satellitebased microwave remote sensing of soil moisture have an adequate spatial resolution for representing the processes in which we are interested? How does its spatial representativeness compare to other products we are used to dealing with (e.g. NDVI, surface temperature, etc.)? 3. Does gravitybased remote sensing of terrestrial water storage have a spatial resolution adequate for representing the processes of interest? What processes can and cannot be characterized at this resolution? 4. What are some of the potential challenges with integrating soil moisture or terrestrial water storage products with the VI or surface temperature products that are also used for characterizing evapotranspiration and the surface water status?