M. HEIMANN results 27
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Bottlenose dolphins (Tursiops truncatus) rely on frequency- and amplitude-modulated whistles to communicate, and noise exposure can inhibit the success of acoustic communication through masking or causing behavioral changes in the animal. At the US Navy Marine Mammal Program (MMP) in San Diego, CA, dolphins are housed in netted enclosures in the San Diego Bay and exposed to noise from vessels, unmanned underwater vehicles, and...
Pan‐Arctic soil moisture control on tundra carbon sequestration and plant productivityNARA Subscribed
Long‐term atmospheric CO 2 concentration records have suggested a reduction in the positive effect of warming on high‐latitude carbon uptake since the 1990s. A variety of mechanisms have been proposed to explain the reduced net carbon sink of northern ecosystems with increased air temperature, including water stress on vegetation and increased respiration over recent decades. However, the lack of consistent long‐term carbon fl...
The CO 2 record at the Amazon Tall Tower Observatory: A new opportunity to study processes on seasonal and inter‐annual scalesNARA Subscribed
High‐quality atmospheric CO 2 measurements are sparse in Amazonia, but can provide critical insights into the spatial and temporal variability of sources and sinks of CO 2 . In this study, we present the first 6 years (2014–2019) of continuous, high‐precision measurements of atmospheric CO 2 at the Amazon Tall Tower Observatory (ATTO, 2.1°S, 58.9°W). After subtracting the simulated background concentrations from our observatio...
Causes of slowing‐down seasonal CO 2 amplitude at Mauna LoaNARA Subscribed
Changing amplitude of the seasonal cycle of atmospheric CO 2 (SCA) in the northern hemisphere is an emerging carbon cycle property. Mauna Loa (MLO) station (20°N, 156°W), which has the longest continuous northern hemisphere CO 2 record, shows an increasing SCA before the 1980s ( p 2 fertilization. This challenges the view that CO 2 fertilization is the dominant cause of emergent SCA trends at northern sites south of 40°N. The...
Warming temperatures are likely to accelerate permafrost thaw in the Arctic, potentially leading to the release of old carbon previously stored in deep frozen soil layers. Deeper thaw depths in combination with geomorphological changes due to the loss of ice structures in permafrost, may modify soil water distribution, creating wetter or drier soil conditions. Previous studies revealed higher ecosystem respiration rates under...
A temporally and spatially resolved estimate of the global surface-ocean CO2 partial pressure field and the sea–air CO2 flux is presented, obtained by fitting a simple data-driven diagnostic model of ocean mixed-layer biogeochemistry to surface-ocean CO2 partial pressure data from the SOCAT v1.5 database. Results include seasonal, interannual, and short-term (daily) variations. In most regions, estimated seasonality is well co...
Characterization of ecosystem responses to climatic controls using artificial neural networksNARA Subscribed
Understanding and modeling ecosystem responses to their climatic controls is one of the major challenges for predicting the effects of global change. Usually, the responses are implemented in models as parameterized functional relationships of a fixed type. In contrast, the inductive approach presented here based on artificial neural networks (ANNs) allows the relationships to be extracted directly from the data . It has been...
Seven years of recent European net terrestrial carbon dioxide exchange constrained by atmospheric observationsNARA Subscribed
We present an estimate of net ecosystem exchange (NEE) of CO 2 in Europe for the years 2001–2007. It is derived with a data assimilation that uses a large set of atmospheric CO 2 mole fraction observations (∼70 000) to guide relatively simple descriptions of terrestrial and oceanic net exchange, while fossil fuel and fire emissions are prescribed. Weekly terrestrial sources and sinks are optimized (i.e., a flux inversion) for...
Outbreak of betanodavirus infection in tilapia, Oreochromis niloticus (L.), in fresh waterNARA Subscribed
A betanodavirus associated with a massive mortality was isolated from larvae of tilapia, Oreochromis niloticus , maintained in fresh water at 30 °C . Histopathology revealed vacuolation of the nervous system, suggesting an infection by a betanodavirus. The virus was identified by indirect fluorescent antibody test in the SSN1 cell line and further characterized by sequencing of a PCR product. Sequencing of the T4 region of the...
The European CARBOEUROPE/FLUXNET monitoring sites, spatial remote sensing observations via the EOS‐MODIS sensor and ecosystem modelling provide independent and complementary views on the effect of the 2003 heatwave on the European biosphere's productivity and carbon balance. In our analysis, these data streams consistently demonstrate a strong negative anomaly of the primary productivity during the summer of 2003. FLUXNET eddy...
Reconciling Carbon-cycle Concepts, Terminology, and MethodsNARA Subscribed
Model–data synthesis in terrestrial carbon observation: methods, data requirements and data uncertainty specificationsNARA Subscribed
Systematic, operational, long‐term observations of the terrestrial carbon cycle (including its interactions with water, energy and nutrient cycles and ecosystem dynamics) are important for the prediction and management of climate, water resources, food resources, biodiversity and desertification. To contribute to these goals, a terrestrial carbon observing system requires the synthesis of several kinds of observation into terr...