FY 2008 Accomplishments
The CU fiscal year '08 spans from July 1, 2007 to June 20, 2008.
Remote Sensing with Unmanned Aircraft Systems (UAS)
At the end of the 2007 Greenland summer field season, researchers demonstrated the use of UAS to gather multi-mode scientific data over the ice sheets and surrounding glacially-carved valleys. Two UAS (at right) and their sensors flew eight flights during the week of August 21, 2007, in the vicinity of Kangerlussuaq International Airport. This project was successful in many respects: it demonstrated that scientific UAS missions could be flown from the main International Airport in Greenland, proved the viability of UAS as a platfom for synthetic aperture radar or other imaging sensors, showed that hyperspectral imaging of supraglacial lakes can be used for depth characterizations, and demonstrated how small UAS can be launched and recovered in the Arctic environment. This project further illustrated that international cooperation can allow autonomous unmanned datacollection platforms to be used in the pursuit of new scientific knowledge. The combination of these attributes could be extremely useful in future satellite calibration and validation efforts, such as CryoSat 2.
Cryospheric Change
The annual melt signal in Greenland since 1979 is highly variable with a standard deviation that is 28 percent of the mean (figure at right). Error bars on the annual total melt area are computed for the first time based on the GC-Net air temperature record. The total melt area in Greenland has increased at 1.4 percent per year since 1979 (91 percent significance.) The record melt year in 2007 lies 10 percent above the previous high in 2005. The 1992 melt year, following Mt. Pinatubo's eruption, is the minimum melt year on record at two standard deviations below the mean, followed closely by 1996. Peak melt occurs, on average, on August 1. Increasing trends during July and August are largely responsible for the overall annual trend. The onset and duration of the melt season have not changed significantly.
Hydrology
In 2008, we completed the last phase of our Hydro-Kansas (HK) pilot project, which is a multiinvestigator, multi-disciplinary, multi-institutional project to understand and predict floods in mesoscale watersheds. We installed 12 stream flow gauges at the end of complete Horton-Strahler streams and 14 rainfall-gauging sites in the Whitewater Basin. Rain gauges are being used in tandem with NEXRAD at Wichita for estimating space-time variable rainfall intensity fields. We extended the scope of HK by adding a riparian evapotranspiration component that overcomes the limitations of conventional approaches. A team of new researchers submitted a proposal to NSF in 2007, which was funded for three years in 2008.
Ecology
Rapid sequencing of severe, large-scale disturbances in subalpine forest (photo at right)—such as wind throw, logging, and fire within a 10-year time span—appears to create extreme microenvironmental conditions that lead to spatially heterogeneous forest regrowth. Our work suggests that, while high severity fires appear to reset or equalize some landscape variables such as woody debris, legacies of pre-fire disturbance persist or are amplified in other properties, such as surface soil environment. Landscapes that experience multiple disturbances show extreme ranges in diurnal soil temperatures and little-to-no seedling establishment five years following the fire. This suggests a significantly delayed return to typically uniform subalpine forest, or a future landscape structure that is outside the normal variability expected with single disturbance events. Both conditions will influence carbon stocks and, potentially, regional biodiversity.
Climate Modeling
We had several publications in the last year examining the climatic effects of recent massive irrigation projects in India. This is a particularly interesting case of land surface changes due to human activity, because the changes occurred recently, and good observational records are available. Among our major conclusions, we found that irrigating India has reduced early-season monsoon precipitation, because the land surface cannot heat as quickly in spring. Early-season monsoon precipitation is vital for Indian agriculture. We also found that these changes in the land surface dominate other human effects such as atmospheric CO2 or atmospheric aerosols.
