B33B-1202
Joint Statistical and Dynamical Assessment of Simulated Vegetation Feedbacks on Climate Over the Boreal Forests
Vegetation feedbacks over Asiatic Russia are assessed through a combined statistical and dynamical approach in a fully coupled atmosphere-ocean-land model, FOAM-LPJ. The dynamical assessment is comprised of initial value ensemble experiments in which the forest cover fraction is initially reduced over Asiatic Russia, replaced by grass cover, and then the climatic response is determined. The statistical feedback approach, adopted from previous studies of ocean-atmosphere interactions, is applied to compute the feedback of forest cover on subsequent temperature and precipitation in the control simulation. Both methodologies indicate a year-round positive feedback on temperature and precipitation, strongest in spring and moderately substantial in summer. Reduced boreal forest cover enhances the surface albedo, leading to an extended snow season, lower air temperatures, increased atmospheric stability, and enhanced low cloud cover. Changes in the hydrological cycle include diminished transpiration and moisture recycling, supporting a reduction in precipitation. The close agreement in sign and magnitude between the statistical and dynamical feedback assessments testifies to the reliability of the statistical approach. This study supports the previous finding of a strong positive vegetation feedback on air temperature over Asiatic Russia in the observational record.
B33B-1203
Instability analysis on drainage flow over a complex terrain
The turbulent transport processes that occur within canopies are extremely complex and have not been accurately represented in past models, especially for ecosystems with hilly or mountainous terrain. The stability analysis on the terrain-induced canopy flows is the key to understanding the introduction of pollutants into the atmosphere and the transfer of water from soil and vegetation to the atmosphere. We applied the Computational Fluid Dynamics (CFD) approach to forest environments to simulate airflows within and above canopy. The results of the CFD experiments show three different dynamic regimes of topographic drainage flow that were simulated under different thermal-dynamic conditions: (1) Cold inflow induces drainage flow in the lower part of canopy and strong stratification of airflows within entire canopy; additionally, the model predicts that there is a super stable layer around the maximum LAD level, which is consistent with our canopy flow theory. This super stable layer minimizes vertical land-atmosphere exchange around the middle level of canopy. (2) Warm inflow causes the rapid flushing of land-atmosphere exchange at the location where two opposite air motions meet, this is called the ‘chimney phenomenon'. (3) The oscillation of canopy flow occurs as the inflow temperature is close to the environmental temperature. These CFD simulations are based on fully derived thermal and fluid dynamic equations. In order to clearly understand the physical mechanisms for the transfer between the different dynamic regimes, I utilized the nonlinear dynamics approach to derive the analytical instability conditions of terrain-induced flows from the simplified thermal-hydro-mechanical equations. The analytical derivations are tested against the CFD simulations. These analytical conditions provide a better understanding of transport problem in ecosystem- atmosphere exchanges of water, carbon dioxide, and energy over complex terrain.
B33B-1205
Are The Large-Scale Biosphere-Atmosphere Experiment In Amazonia (LBA) Representative Of Long-Term Climatology? A Study Using Climate Weather Stations In Brazil.
The Large-Scale Biosphere-Atmosphere Experiment in Amazonia has already contributed understanding of the flux exchange between the Amazonian rainforest and atmosphere and other significant components of the ecohydrometeorological system, and it will continue to do so. However, when considering LBA-derived information on whether the Amazon is a source or sink of carbon, or whether land use changes in the Amazon are affecting the local and perhaps global climate, it is important to characterize the period during which the LBA project has been carried out in terms of its climatological context. In other words, to address the question "How does the climate during the LBA data collection period compare with the long-term climatology in Amazon." Such information is not only useful for future project planning but is crucial information for modeling purposes: the calibration or validation of models using LBA data may be influenced by the climate conditions prevalent when these data were collected. This investigates the extent to which the actual period of data collection at LBA sites is representative of the long-term climatology for the sites. The research uses long-term weather station data taken from the databases of Brazilian National Water Agency (Agencia Nacional de Aguas - ANA) and National Oceanic and Atmospheric Administration - National Climatic Data Center division (NOAA-NCDC) for stations located near the Sao Gabriel da Cachoeira, Manaus, Santarem, Caxiuana, Jaru, Sinop, and Bananal LBA sites, and compares these weather station data during the LBA data collection period with the entire dataset available for each weather station. Analysis of the precipitation records demonstrates that the precipitation climate during the LBA study period was not significant different from the long- term climatology at all the LBA sites but that at a few sites the temperature climate during LBA was statistically different.
B33B-1206
High-resolution evapotranspiration estimates for California using satellite imagery and weather station measurements and the Weather Research Forecasting (WRF) model
Spatially distributed potential Evapotranspiration, ET0, has been calculated to produce daily and hourly ET0 maps for the State of California at 2 km2 resolution. Hourly NOAA GOES imager satellite visible data are used to predict daily radiation. These are combined with interpolated California Irrigation Management Information System (CIMIS) weather station meteorological data for temperature, wind speed and humidity to satisfy the Penman-Monteith ET0 equation. In the next step, we investigate the use of the Weather Research Forecasting (WRF) model to improve the spatial estimates of daily evapotranspiration for the state of California. CIMIS real-time weather station and real-time satellite data are integrated into a prognostic version of the WRF model using its data nudging scheme. This paper we compares spatially interpolated climate parameters and evapotranspiration to the output of WRF with and without data assimilation of CIMIS data. The research assists California's Department of Water Resources to better monitor water use and water management. In addition to the scientific advances in understanding short- term weather systems and their impacts on plant resources, there is considerable societal importance, given impacts of current droughts and predictions for significantly reduced winter snow packs in California under some climate change scenarios.
B33B-1207
Spatial Analysis of Chinook Spawning Habitat: GIS Analysis of Warm Water Intrusion Below Iron Gate Dam; Klamath, California
The Klamath River supports several species of salmon including Steelhead, Coho and Chinook. Historically, Klamath has been the third largest producer of salmon on the West coast and an integral part of the California fishery, supporting commercial, recreational and tribal communities. Within the past decade, however, water quality conditions on the Klamath have declined due to increased temperatures and nutrients, depressed dissolved oxygen and elevated turbidity; prompting the EPA to list the Klamath as an impaired river. The effects and spatial extent of elevated temperature below Iron Gate Dam on Chinook salmon spawning were evaluated using ArcMap 9.2 in conjunction with nine USGS gauging stations. Potential habitat layers were derived from DEM and relative bed stability indices. Through the process of Dynamic Segmentation, habitat and water quality were combined and available spawning habitat were quantified. Dynamic Segmentation converts linearly referenced data stored in a table into features that can be displayed and analyzed on a map. By overlaying and intersecting potential salmon spawning habitat layers with water quality the amount of available habitat can be quantified along a linear feature. Analysis indicates reduction of spawning habitat by 24% due to warm water intrusion. This approach also allows for an assessment of the potential impacts on habitat suitability under different climate change scenarios.
B33B-1208
Do Species-specific Hydraulic Traits Predict Ecosystem Response and Community Structure? Evidence From Co-occurring Bryophytes of a Sloping Wetland
Ecosystems comprise a complex assortment species, and each species has a unique set of physiological and anatomical characteristics or traits. Landscape-level forecasts of ecosystem response to climate change can benefit by accounting for species-specific traits. Here, we demonstrate how a hydraulic trait can be quantified and aggregrated to community and ecosystem levels using a model life form and system, bryophytes in a sloping wetland. Growth and reproduction of bryophytes depend on the quantity of external water held, which varies by species. Wetlands provide a soil substrate that supplies either an unlimited amount of water, or at minimum, a shallow water table for part of the year. We hypothesized and confirmed that external water holding capacity of bryophyte species (measured in the laboratory) corresponded to bryophyte community structure along a hydrology gradient in the wetland. In addition, we demonstrated that water holding capacity by species can be aggregated to the level of the wetland ecosystem to reveal an emergent community property, water holding capacity of the bryophyte mat. Our results support ecological theory presented by Paul Keddy (1999) that co-occurring organisms show similarity in resource acquisition along gradients of resource limitation. We promote a conceptual framework that incorporates species-specific traits as modeling currency that can bridge scales.
B33B-1209
Evapotranspiration and River Discharge Interactions With Fire, Partial Success Restoration, and Climate Change
Climate change is likely to have profound effects on water supplies in the southwestern United States. The largest rivers in this region are fed by snowmelt, which is predicted by the IPCC to decrease over the coming years. In the Middle Rio Grande of New Mexico, transpiration from phreatophytic vegetation can represent up to one-third of annual depletions. A flux tower network has been established in New Mexico, termed NM-EPSCoR Fluxnet, is providing valuable information on the eco-hydrological response of riparian and upland ecosystems to climate events (like drought), topographically-driven mesoscale forcing from katabatic and anabatic winds, ecosystem restoration, and post-fire recovery ecology. Following removal of non-native from below a cottonwood canopy causes greater insolation of the soil surface, doubling ground heat flux rates and inverting a portion diel energy balance from a heat sink (i.e., H < 0) to a heat source. The strongest cross-correlation (r = 0.5) between river flow and ET was observed when discharge was lagged 14 days behind ET. Neither drought nor fire modified this lag relationship. However, correlation between discharge and ET disappeared entirely following a canopy fire in 2006. Stomatal resistance cottonwood and co-occurring native and non-native vegetation was most strongly limited by vapor pressure deficit, although stomatal resistance was typically measured below this limit because of these plants' access to groundwater. It is also because of abundant groundwater along the Middle Rio Grande that drought has little effect on water and energy fluxes. As climate changes in this region and groundwater becomes more scarce, changes in community composition to non-native species is expected as native species become isolated from groundwater. With a strong understanding of the factors controlling the riparian water cycle, management of the riparian corridor can be achieved such that depletions are minimized while value of the ecosystem services can be maintained.
B33B-1210
Influence of Solar Exposure on Stream Water Temperature: Implications for Conservation
Stream water temperature is determined by a complex interplay of prevailing meteorology, local riparian canopy structure as it affects solar exposure, streambed morphology, and surface and subsurface flow patterns. We examined spatio-temporal variation in temperature regimes with respect to conservation of aquatic organisms of San Francisquito Creek (San Francisco Peninsula, California). Analyses synthesized measurements of meteorology from nearby weather stations, water temperature from a network of sensors, riparian canopy structure and solar exposure from hemispherical (fisheye) photography, stream morphology from field characterization and geographic information system (GIS) analysis, and stream flow and water temperature from gauging stations. We modeled stream temperature dynamics based on energy balance, with a focus on energy input from solar radiation. Water temperature co-varied with air temperature, with diurnal and seasonal lags. Stream reaches with high solar exposure displayed relatively high temperature variability (up to 5° C differential from baseline), whereas shaded reaches displayed only modest temperature variability (0.5-1.0° C differential). Subsurface flow through gravel beds decreased temperature (2-3° C decrease). Management of stream habitat to include a diversity of suitable temperature regimes is essential for conservation of species such as steelhead trout ( Oncorhynchus mykiss), which requires relatively cool conditions, and California red-legged frog ( Rana aurora draytonii) and western pond turtle ( Clemmys marmorata), which require warmer conditions. This approach can be applied to a broad spectrum of streams for habitat assessment, for stream conservation and restoration to accommodate diverse habitat needs, and for examination of potential impacts of climate change. http://www.creeksidescience.com
B33B-1211
Climate Variability in Coastal Ecosystems - Use of MODIS Land Surface and Sea Surface Temperature Observations
The intertidal zone, with its complex blend of marine and terrestrial environments, is one of the intensively studied ecosystems, in understanding the effects of climate change on species abundance and distribution. As climatic conditions change, the geographic limits of the intertidal species will likely move towards more tolerable coastal conditions. Traditionally, understanding climate change effects through species physiologic response have involved use of in situ measurements and thermal engineering models. But these approaches are constrained by their data intensive requirements and may not be suitable for predicting change patterns relevant to large scale species distributions. Satellite remote sensing provides an alternate approach, given the regular global coverage at moderate spatial resolutions. The present study uses six years of land surface temperature (LST) and sea surface temperature (SST) data from MODIS/Terra instrument along various coastlines around the globe - East and West Coast US, Southern Africa, Northern Japan and New Zealand. Apart from the dominant annual cycle in LST and SST, the other seasonal cycles vary from dominant semi-annual cycles in lower latitudes to 1.5 and 2 year cycles at higher latitudes. The monthly anomalies show strong spatial structure at lower latitudes when compared to higher latitudes, with the exception of US east coast, where the spatial structure extended almost along the whole coastline, indicating strong regulation from the Gulf Stream. The patterns along different coast lines are consistent with the atmospheric and ocean circulation patterns existing at those regions. These results suggest that the climatology at the coastal regions can be adequately represented using satellite-based temperature data, thus enabling further research in understanding the effects of climate change on species abundance and distribution at larger scales.
B33B-1212
TERENO ("Terrestrial Environmental Observatories"): Establishment and Upgrading of a Terrestrial Observatory "Alpine upland" for Long Term Observations of the Impact of Global Change Factors on Biosphere-Hydrosphere-Atmosphere Interactions
Long term observations are an indispensable pre-requisite to improve our knowledge of the complex biosphere- hydrosphere-atmosphere (BHA)-interactions and to detect and analyze the impact of Global Change parameters on these interactions as well as to develop, improve and validate BHA model systems. As an integral part of the Helmholtz initiative TERENO to establish/upgrade and equip terrestrial observatories for long term observations (> 10 years) on the effects of Global Change on complex terrestrial ecosystems, an observatory "Alpine Upland", operated jointly by the research centers FZK (Forschungszentrum Karlsruhe) and GSF (National Research Center for Environment and Health) is established. The central objectives of the scientific work performed by Forschungszentrum Karlsruhe within this observatory are: Characterization and quantification of changes of the (a) coupled C-/N-cycles and C-/N-storage (b)biosphere-atmosphere exchange (trace gases/energy flux/albedo) (c)vegetation and microbial biodiversity and of the temporal dynamics of matter- turnover and –exchange coupled to this change in biodiversity (d)terrestrial hydrology (alpine water budget, precipitation variability, extreme hydrometeorological events, seapage water quality/quantity, water retention capacity) in important climate- and use-sensitive ecosystem types within the pre-alpine region (e.g. alpine meadows, forests) under changing conditions of climate, management and nutrient deposition (atmospheric N-input). Besides upgrading of the already existing long term observation stations in the pre-alpine region ("The Höglwald Forest" (FZK) and the agricultural long term observation station "Scheyern" (for details see separate contribution of GSF) FZK will establish a "Climate-Feedback Observatory" at which the effects of predicted future changes in temperature and precipitation amount/distribution within the pre-alpine region on the complex BHA interactions will be studied applying a long term in-situ simulation experiment. For this a lysimeter network will be realized in which soil monoliths are transplanted along the existing natural gradient in temperature and precipitation within the alpine region. Details of this experimental approach will be presented.
B33B-1213
Independent Wetland Vegetation Response to Climate Variability and Anthropogenic Hydrologic Control, Everglades, FL, USA
The response of a wetland landscape composed of multiple, distinct, plant communities to a single stimulus, whether it results from natural climate variability or human alterations, should not be assumed to be uniform across the entire landscape. The Florida Everglades is such a landscape where elevated sawgrass ridges are immediately next to water lily dominated sloughs, known collectively as the sawgrass ridge and slough landscape (SRS). The distribution of the Everglades individual sawgrass ridge and slough plant communities within the SRS was altered by 20th century construction of water control structures (canals, levees, and dikes) and alteration of the natural hydrologic regime. Although restoration planning to stabilize the remaining ridge and slough habitats is underway, little is known about the landscape's origin and response to past hydrologic changes. Analysis of pollen assemblages from transects of piston cores collected across SRS indicate that sawgrass ridges and sloughs have been vegetationally distinct from one another since the mid Holocene. Modern sawgrass ridges formed from a marsh-like environment, whereas slough communities occupied their present sites throughout the history of the sites. Ridge formation was triggered by intervals of drier climate (i.e., the Medieval Warm Period and Little Ice Age) and changes in the mean position of the Intertropical Convergence Zone. The sloughs are temporarily composed of more marsh plants during drier conditions, but quickly return to their original state when precipitation increases. During the 20th century, sloughs appear to be strongly influenced by North Atlantic Oscillation (NAO) variability in spite of water management practices, while the sawgrass ridges respond primarily to [water management] anthropogenic changes in hydrology. Our evidence that, the sawgrass ridge and slough landscape communities can act independent of one another to changes in hydrology, indicates that restoring the pre-20th century hydrology may not restore all aspects of the pre-20th century landscape structure.