scholarly journals High-resolution data on the impact of warming on soil CO2 efflux from an Asian monsoon forest

2017 ◽  
Vol 4 (1) ◽  
Author(s):  
Naishen Liang ◽  
Munemasa Teramoto ◽  
Masahiro Takagi ◽  
Jiye Zeng
Keyword(s):  
High Resolution ◽  
Asian Monsoon ◽  
Soil Co2 Efflux ◽  
Co2 Efflux ◽  
Soil Co2 ◽  
High Resolution Data ◽  
Monsoon Forest ◽  
The Impact ◽  
Resolution Data

scholarly journals Paired refinement under the control of PAIREF

IUCrJ ◽  
2020 ◽  
Vol 7 (4) ◽  
pp. 681-692
Author(s):  
Martin Malý ◽  
Kay Diederichs ◽  
Jan Dohnálek ◽  
Petr Kolenko
Keyword(s):  
High Resolution ◽  
Diffraction Data ◽  
Structure Refinement ◽  
Data Sets ◽  
High Resolution Data ◽  
Density Maps ◽  
New Feature ◽  
And Control ◽  
The Impact ◽  
Resolution Data

Crystallographic resolution is a key characteristic of diffraction data and represents one of the first decisions an experimenter has to make in data evaluation. Conservative approaches to the high-resolution cutoff determination are based on a number of criteria applied to the processed X-ray diffraction data only. However, high-resolution data that are weaker than arbitrary cutoffs can still result in the improvement of electron-density maps and refined structure models. Therefore, the impact of reflections from resolution shells higher than those previously used in conservative structure refinement should be analysed by the paired refinement protocol. For this purpose, a tool called PAIREF was developed to provide automation of this protocol. As a new feature, a complete cross-validation procedure has also been implemented. Here, the design, usage and control of the program are described, and its application is demonstrated on six data sets. The results prove that the inclusion of high-resolution data beyond the conventional criteria can lead to more accurate structure models.

scholarly journals Improving Short-Term Storm Predictions by Assimilating both Radar Radial-Wind and Reflectivity Observations

2008 ◽  
Vol 23 (3) ◽  
pp. 373-391 ◽  
Author(s):  
Qingyun Zhao ◽  
John Cook ◽  
Qin Xu ◽  
Paul R. Harasti
Keyword(s):  
High Resolution ◽  
Data Assimilation ◽  
Radar Data ◽  
Naval Research ◽  
Short Term ◽  
High Resolution Data ◽  
Reflectivity Data ◽  
The Impact ◽  
Data Assimilation System ◽  
Resolution Data

Abstract A high-resolution data assimilation system is under development at the Naval Research Laboratory (NRL). The objective of this development is to assimilate high-resolution data, especially those from Doppler radars, into the U.S. Navy’s Coupled Ocean–Atmosphere Mesoscale Prediction System to improve the model’s capability and accuracy in short-term (0–6 h) prediction of hazardous weather for nowcasting. A variational approach is used in this system to assimilate the radar observations into the model. The system is upgraded in this study with new capabilities to assimilate not only the radar radial-wind data but also reflectivity data. Two storm cases are selected to test the upgraded system and to study the impact of radar data assimilation on model forecasts. Results from the data assimilation experiments show significant improvements in storm prediction especially when both radar radial-wind and reflectivity observations are assimilated and the analysis incremental fields are adequately constrained by the model’s dynamics and properly adjusted to satisfy the model’s thermodynamical balance.

scholarly journals Summer drought reduces total and litter-derived soil CO<sub>2</sub> effluxes in temperate grassland – clues from a <sup>13</sup>C litter addition experiment

2010 ◽  
Vol 7 (3) ◽  
pp. 1031-1041 ◽  
Author(s):  
O. Joos ◽  
F. Hagedorn ◽  
A. Heim ◽  
A. K. Gilgen ◽  
M. W. I. Schmidt ◽  
...  
Keyword(s):  
Climate Change ◽  
Soil Co2 Efflux ◽  
Temperate Grassland ◽  
Summer Drought ◽  
Co2 Efflux ◽  
Soil Co2 ◽  
Drought Period ◽  
Litter Addition ◽  
C Balance ◽  
The Impact

Abstract. Current climate change models predict significant changes in rainfall patterns across Europe. To explore the effect of drought on soil CO2 efflux (FSoil) and on the contribution of litter to FSoil we used rain shelters to simulate a summer drought (May to July 2007) in an intensively managed grassland in Switzerland by reducing annual precipitation by around 30% similar to the hot and dry year 2003 in Central Europe. We added 13C-depleted as well as unlabelled grass/clover litter to quantify the litter-derived CO2 efflux (FLitter). Soil CO2 efflux and the 13C/12C isotope ratio (δ13C) of the respired CO2 after litter addition were measured during the growing season 2007. Drought significantly decreased FSoil in our litter addition experiment by 59% and FLitter by 81% during the drought period itself (May to July), indicating that drought had a stronger effect on the CO2 release from litter than on the belowground-derived CO2 efflux (FBG, i.e. soil organic matter (SOM) and root respiration). Despite large bursts in respired CO2 induced by the rewetting after prolonged drought, drought also reduced FSoil and FLitter during the entire 13C measurement period (April to October) by 26% and 37%, respectively. Overall, our findings show that drought decreased FSoil and altered its seasonality and its sources. Thus, the C balance of temperate grassland soils respond sensitively to changes in precipitation, a factor that needs to be considered in regional models predicting the impact of climate change on ecosystems C balance.

scholarly journals Summer drought reduces total and litter-derived soil CO<sub>2</sub> effluxes in temperate grassland – clues from a <sup>13</sup>C litter addition experiment

2009 ◽  
Vol 6 (6) ◽  
pp. 11005-11034 ◽  
Author(s):  
O. Joos ◽  
F. Hagedorn ◽  
A. Heim ◽  
A. K. Gilgen ◽  
M. W. I. Schmidt ◽  
...  
Keyword(s):  
Climate Change ◽  
Soil Co2 Efflux ◽  
Temperate Grassland ◽  
Summer Drought ◽  
Co2 Efflux ◽  
Soil Co2 ◽  
Drought Period ◽  
Litter Addition ◽  
Change Models ◽  
The Impact

Abstract. Current climate change models predict significant changes in rainfall patterns across Europe. To explore the effect of drought on soil CO2 efflux (FSoil) and on the contribution of litter to FSoil we used rainout shelters to simulate a summer drought (May to July 2007) in an intensively managed grassland in Switzerland, and to reduce annual precipitation by around 30% similar to the hot and dry year 2003 in Central Europe. We added 13C-depleted as well as unlabelled grass/clover litter to quantify the litter-derived CO2 efflux (FLitter). Soil CO2 efflux and the 13C/12C isotope ratio (δ13C) of the respired CO2 after litter addition were measured during the growing season 2007. Drought significantly decreased FSoil in our litter addition experiment by 52% and FLitter by 74% during the drought period itself (May to July), indicating that drought had a stronger effect on the CO2 release from litter than on the belowground-derived CO2 efflux (FBG, i.e. soil organic matter (SOM) and root respiration). Despite large bursts in respired CO2 induced by the rewetting after prolonged drought, drought also reduced FSoil and FLitter during the entire 13C measurement period (April to October) by 32% and 33%, respectively. Overall our findings highlight i) the sensitivity of temperate grassland soils to changes in precipitation, a factor that needs to be considered in regional models predicting the impact of climate change, and ii) the need to quantify the response of the different components of soil CO2 efflux to fully understand climate change impacts on ecosystem carbon balance.

scholarly journals The impact of extreme summer drought on the short-term carbon coupling of photosynthesis to soil CO<sub>2</sub> efflux in a temperate grassland

2013 ◽  
Vol 10 (7) ◽  
pp. 11671-11704 ◽  
Author(s):  
S. Burri ◽  
P. Sturm ◽  
U. E. Prechsl ◽  
A. Knohl ◽  
N. Buchmann
Keyword(s):  
Climate Change ◽  
Tracer Uptake ◽  
Soil Co2 Efflux ◽  
Future Climate Change ◽  
Summer Drought ◽  
Co2 Efflux ◽  
Soil Co2 ◽  
Short Term ◽  
Grass Sward ◽  
The Impact

Abstract. Along with predicted climate change, increased risks for summer drought are projected for Central Europe. However, large knowledge gaps exist in terms of how drought events influence the short-term ecosystem carbon cycle. Here, we present results from 13CO2 pulse labeling experiments at an intensively managed lowland grassland in Switzerland. We investigated the effect of extreme summer drought on the short-term coupling of freshly assimilated photosynthates in shoots to roots as well as to soil CO2 efflux. Summer drought was simulated using rainout shelters during two field seasons (2010 and 2011). Soil CO2 efflux and its isotopic composition were measured with custom-built chambers coupled to a quantum cascade laser spectrometer (QCLAS-ISO, Aerodyne Research Inc., MA, USA). During the 90 min pulse labeling experiments, we added 99.9 atom % 13CO2 to the grass sward. In addition to the isotopic analysis of soil CO2 efflux, this label was traced over 31 days into bulk shoots, roots and soil. Drought reduced the incorporation of recently fixed carbon into shoots and increased carbon allocation below-ground relative to total tracer uptake. Contrary to our hypothesis, we did not find a change in allocation speed in response to drought, although drought clearly reduced soil CO2 efflux rates. 19 days after pulse labeling, only about 60% of total tracer uptake was lost via soil CO2 efflux under drought compared to about 75% under control conditions. Predisposition of grassland by spring drought lead to different responses to summer drought in 2011 compared to 2010, suggesting increased sensitivity of grassland to consecutive drought events as predicted under future climate change.

scholarly journals The impact of extreme summer drought on the short-term carbon coupling of photosynthesis to soil CO<sub>2</sub> efflux in a temperate grassland

2014 ◽  
Vol 11 (4) ◽  
pp. 961-975 ◽  
Author(s):  
S. Burri ◽  
P. Sturm ◽  
U. E. Prechsl ◽  
A. Knohl ◽  
N. Buchmann
Keyword(s):  
Soil Co2 Efflux ◽  
Soil Drought ◽  
Summer Drought ◽  
Co2 Efflux ◽  
Soil Co2 ◽  
Short Term ◽  
Below Ground ◽  
Intensively Managed ◽  
Grass Sward ◽  
The Impact

Abstract. Along with predicted climate change, increased risks for summer drought are projected for Central Europe. However, large knowledge gaps exist in terms of how drought events influence the short-term ecosystem carbon cycle. Here, we present results from 13CO2 pulse labeling experiments at an intensively managed lowland grassland in Switzerland. We investigated the effect of extreme summer drought on the short-term coupling of freshly assimilated photosynthates in shoots to roots as well as to soil CO2 efflux. Summer drought was simulated using rainout shelters during two field seasons (2010 and 2011). Soil CO2 efflux and its isotopic composition were measured with custom-built chambers coupled to a quantum cascade laser spectrometer (QCLAS-ISO, Aerodyne Research Inc., MA, USA). During the 90 min pulse labeling experiments, we added 99.9 atom % 13CO2 to the grass sward. In addition to the isotopic analysis of soil CO2 efflux, this label was traced over 31 days into bulk shoots, roots and soil. Drought reduced the incorporation of recently fixed carbon into the shoots, but increased the relative allocation of fresh assimilates below ground compared to the control grasslands. Contrary to our hypothesis, we did not find a change of allocation speed in response to drought. Although drought clearly reduced soil CO2 efflux rates, about 75% of total tracer uptake in control plots was lost via soil CO2 efflux during 19 days after pulse labeling, compared to only about 60% under drought conditions. Thus, the short-term coupling of above- and below-ground processes was reduced in response to summer drought. The occurrence of a natural spring drought in 2011 lead to comparable albeit weaker drought responses increasing the confidence in the generalizability of our findings.

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