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Articles 1 - 11 of 11
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Geostatistical Analysis Of An Experimental Stratigraphy, Y Zhang, M Person, C Paola, C W. Gable, X H. Wen, J M. Davis
Geostatistical Analysis Of An Experimental Stratigraphy, Y Zhang, M Person, C Paola, C W. Gable, X H. Wen, J M. Davis
Earth Sciences
[1] A high-resolution stratigraphic image of a flume-generated deposit was scaled up to sedimentary basin dimensions where a natural log hydraulic conductivity (ln( K)) was assigned to each pixel on the basis of gray scale and conductivity end-members. The synthetic ln( K) map has mean, variance, and frequency distributions that are comparable to a natural alluvial fan deposit. A geostatistical analysis was conducted on selected regions of this map containing fluvial, fluvial/ floodplain, shoreline, turbidite, and deepwater sedimentary facies. Experimental ln(K) variograms were computed along the major and minor statistical axes and horizontal and vertical coordinate axes. Exponential and power …
Effects Of Uncertainty In Climate Inputs On Simulated Evapotranspiration And Runoff In The Western Arctic, Michael A. Rawlins, Steve Frolking, Richard B. Lammers, Charles Vorosmarty
Effects Of Uncertainty In Climate Inputs On Simulated Evapotranspiration And Runoff In The Western Arctic, Michael A. Rawlins, Steve Frolking, Richard B. Lammers, Charles Vorosmarty
Earth Sciences
Hydrological models require accurate precipitation and air temperature inputs in order to adequately depict water fluxes and storages across Arctic regions. Biases such as gauge undercatch, as well as uncertainties in numerical weather prediction reanalysis data that propagate through water budget models, limit the ability to accurately model the terrestrial arctic water cycle. A hydrological model forced with three climate datasets and three methods of estimating potential evapotranspiration (PET) was used to better understand the impact of these processes on simulated water fluxes across the Western Arctic Linkage Experiment (WALE) domain. Climate data were drawn from the NCEP–NCAR reanalysis (NNR) …
Evaluation Of The Seawinds Scatterometer For Regional Monitoring Of Vegetation Phenology, Steve Frolking, Tom Milliman, Kyle Mcdonald, John Kimball, Maosheng Zhao, Mark Fahnestock
Evaluation Of The Seawinds Scatterometer For Regional Monitoring Of Vegetation Phenology, Steve Frolking, Tom Milliman, Kyle Mcdonald, John Kimball, Maosheng Zhao, Mark Fahnestock
Earth Sciences
Phenology, or the seasonality of recurring biological events such as vegetation canopy development and senescence, is a primary constraint on global carbon, water and energy cycles. We analyzed multiseason Ku-band radar backscatter measurements from the SeaWinds-on-QuikSCAT scatterometer to determine canopy phenology and growing season vegetation dynamics from 2000 to 2002 at 27 sites representing major global land cover classes and regionally across most of North America. We compared these results with similar information derived from the MODIS leaf area index (LAI) data product (MOD-15A2). In site-level linear regression analysis, the correspondence between radar backscatter and LAI was significant (p < 0.05) at most but not all sites and was generally higher (R2 …
Comparing Co2 Retrieved From Atmospheric Infrared Sounder With Model Predictions: Implications For Constraining Surface Fluxes And Lower-To-Upper Troposphere Transport, Yogesh K. Tiwari, Manuel Gloor, Richard Engelen, Frederic Chevallier, Christian Rodenbeck, Stefan Korner, P Peylin, Rob Braswell, M Heimann
Comparing Co2 Retrieved From Atmospheric Infrared Sounder With Model Predictions: Implications For Constraining Surface Fluxes And Lower-To-Upper Troposphere Transport, Yogesh K. Tiwari, Manuel Gloor, Richard Engelen, Frederic Chevallier, Christian Rodenbeck, Stefan Korner, P Peylin, Rob Braswell, M Heimann
Earth Sciences
Large-scale carbon sources and sinks can be estimated by combining atmospheric CO2concentration data with atmospheric transport inverse modeling. This approach has been limited by sparse spatiotemporal tropospheric sampling. CO2 estimates from space using observations on recently launched satellites (Atmospheric Infrared Sounder (AIRS)), or platforms to be launched (Infrared Atmospheric Sounding Interferometer (IASI), Orbiting Carbon Observatory (OCO)) have the potential to fill some of these gaps. Here we assess the realism of initial AIRS-based mid-to-upper troposphere CO2 estimates from European Centre for Medium-Range Weather Forecasts by comparing them with simulations of two transport models (TM3 and Laboratoire …
Ice Core Evidence For A Second Volcanic Eruption Around 1809 In The Northern Hemisphere, Kaplan Yalcin, Cameron P. Wake, K Kreutz, Mark S. Germani, Sallie I. Whitlow
Ice Core Evidence For A Second Volcanic Eruption Around 1809 In The Northern Hemisphere, Kaplan Yalcin, Cameron P. Wake, K Kreutz, Mark S. Germani, Sallie I. Whitlow
Earth Sciences
A volcanic signal observed in ice cores from both polar regions six years prior to Tambora is attributed to an unknown tropical eruption in 1809. Recovery of dacitic tephra from the 1809 horizon in a Yukon ice core (Eclipse) that is chemically distinct from andesitic 1809 tephra found in Antarctic ice cores indicates a second eruption in the Northern Hemisphere at this time. Together with the similar magnitude and timing of the 1809 volcanic signal in the Arctic and Antarctic, this could suggest a large tropical eruption produced the sulfate and Antarctic tephra and a minor Northern Hemisphere eruption produced …
Changes In Moisture And Energy Fluxes Due To Agricultural Land Use And Irrigation In The Indian Monsoon Belt, Ellen M. Douglas, Dev Niyogi, Steve Frolking, Jagadeesh Babu Yeluripati, Roger A. Pielke Sr, Nivedita Niyogi, Charles Vorosmarty, U C. Mohanty
Changes In Moisture And Energy Fluxes Due To Agricultural Land Use And Irrigation In The Indian Monsoon Belt, Ellen M. Douglas, Dev Niyogi, Steve Frolking, Jagadeesh Babu Yeluripati, Roger A. Pielke Sr, Nivedita Niyogi, Charles Vorosmarty, U C. Mohanty
Earth Sciences
We present a conceptual synthesis of the impact that agricultural activity in India can have on land-atmosphere interactions through irrigation. We illustrate a “bottom up” approach to evaluate the effects of land use change on both physical processes and human vulnerability. We compared vapor fluxes (estimated evaporation and transpiration) from a pre-agricultural and a contemporary land cover and found that mean annual vapor fluxes have increased by 17% (340 km3) with a 7% increase (117 km3) in the wet season and a 55% increase (223 km3) in the dry season. Two thirds of this …
In Situ Evidence For Renitrification In The Arctic Lower Stratosphere During The Polar Aura Validation Experiment (Pave), Jack E. Dibb, Eric Scheuer, Melody A. Avery, G W. Sachse
In Situ Evidence For Renitrification In The Arctic Lower Stratosphere During The Polar Aura Validation Experiment (Pave), Jack E. Dibb, Eric Scheuer, Melody A. Avery, G W. Sachse
Earth Sciences
In-situ measurements of nitric acid (HNO3), ozone (O3), and nitrous oxide (N2O) were made from the NASA DC-8 during the Polar Aura Validation Experiment in January/February 2005. In the lower stratosphere (9–12.5 km, potential temperature 300–350 K) characteristic compact relationships were observed between all three gases. The ratio HNO3/O3 averaged 3.5 (±0.7) ppt/ppb. Samples with enhanced HNO3/O3 (>4.0) were most abundant under the edge of the Arctic Polar vortex in airmasses with enhanced mixing ratios of both gases (>400 ppb O3 and >2000 ppt HNO …
Observations Of Hono By Laser-Induced Fluorescence At The South Pole During Antci 2003, W Liao, A T. Case, J Mastromarino, D Tan, Jack E. Dibb
Observations Of Hono By Laser-Induced Fluorescence At The South Pole During Antci 2003, W Liao, A T. Case, J Mastromarino, D Tan, Jack E. Dibb
Earth Sciences
Observations of nitrous acid (HONO) by laser-induced fluorescence (LIF) at the South Pole taken during the Antarctic Troposphere Chemistry Investigation (ANTCI), which took place over the time period of Nov. 15, 2003 to Jan. 4, 2004, are presented here. The median observed mixing ratio of HONO 10 m above the snow was 5.8 pptv (mean value 6.3 pptv) with a maximum of 18.2 pptv on Nov 30th, Dec 1st, 3rd, 15th, 17th, 21st, 22nd, 25th, 27th and 28th. The measurement uncertainty is ±35%. The LIF HONO observations are compared to concurrent HONO observations performed by mist chamber/ion chromatography (MC/IC). The …
Evaluation Of Trends In Derived Snowfall And Rainfall Across Eurasia And Linkages With Discharge To The Arctic Ocean, Michael A. Rawlins, C J. Willmot, A Shiklomanov, Ernst Linder, Steve Frolking, Richard B. Lammers, Charles Vorosmarty
Evaluation Of Trends In Derived Snowfall And Rainfall Across Eurasia And Linkages With Discharge To The Arctic Ocean, Michael A. Rawlins, C J. Willmot, A Shiklomanov, Ernst Linder, Steve Frolking, Richard B. Lammers, Charles Vorosmarty
Earth Sciences
To more fully understand the role of precipitation in observed increases in freshwater discharge to the Arctic Ocean, data from a new archive of bias-adjusted precipitation records for the former USSR (TD9813), along with the CRU and Willmott-Matsuura data sets, were examined for the period 1936–1999. Across the six largest Eurasian river basins, snowfall derived from TD9813 exhibits a strongly significant increase until the late 1950s and a moderately significant decrease thereafter. A strongly significant decline in derived rainfall is also noted. Spatially, snowfall increases are found primarily across north-central Eurasia, an area where the rainfall decreases are most prominent. …
Statistical Uncertainty Of Eddy Flux–Based Estimates Of Gross Ecosystem Carbon Exchange At Howland Forest, Maine, Stephen Hagen, Rob Braswell, Ernst Linder, Steve Frolking, Andrew D. Richardson, David Y. Hollinger
Statistical Uncertainty Of Eddy Flux–Based Estimates Of Gross Ecosystem Carbon Exchange At Howland Forest, Maine, Stephen Hagen, Rob Braswell, Ernst Linder, Steve Frolking, Andrew D. Richardson, David Y. Hollinger
Earth Sciences
We present an uncertainty analysis of gross ecosystem carbon exchange (GEE) estimates derived from 7 years of continuous eddy covariance measurements of forest-atmosphere CO2fluxes at Howland Forest, Maine, USA. These data, which have high temporal resolution, can be used to validate process modeling analyses, remote sensing assessments, and field surveys. However, separation of tower-based net ecosystem exchange (NEE) into its components (respiration losses and photosynthetic uptake) requires at least one application of a model, which is usually a regression model fitted to nighttime data and extrapolated for all daytime intervals. In addition, the existence of a significant amount …
The Impact Of A Northern Peatland On The Earth’S Radiative Budget: Sustained Methane Emission Versus Sustained Carbon Sequestration, Steve Frolking, Nigel T. Roulet, Jan Fuglestvedt
The Impact Of A Northern Peatland On The Earth’S Radiative Budget: Sustained Methane Emission Versus Sustained Carbon Sequestration, Steve Frolking, Nigel T. Roulet, Jan Fuglestvedt
Earth Sciences
Northern peatlands sequester carbon and emit methane, and thus have both cooling and warming impacts on the climate system through their influence on atmospheric burdens of CO2 and CH4. These competing impacts are usually compared by the global warming potential (GWP) methodology, which determines the equivalent CO2 annual emission that would have the same integrated radiative forcing impact over a chosen time horizon as the annual CH4 emission. We use a simple model of CH4 and CO2 pools in the atmosphere to extend this analysis to quantify the dynamics, over years to millennia, of the net radiative forcing impact of …