Open Access. Powered by Scholars. Published by Universities.®

Digital Commons Network™

Open Access. Powered by Scholars. Published by Universities.®

Earth Sciences

Institution
Keyword
Publication Year
Publication
Publication Type
File Type

Articles 51061 - 51090 of 59413

Full-Text Articles in Entire DC Network

Characteristics Of The Weathering Zones Developed Within The Tuffs Of The Midas Monument, Tamer Topal, Burak Sözmen Jan 2001

Characteristics Of The Weathering Zones Developed Within The Tuffs Of The Midas Monument, Tamer Topal, Burak Sözmen

Turkish Journal of Earth Sciences

The Midas monument, an impressive cult facade located in the southern part of the Eskişehir province in central Anatolia, Turkey, was made within tuffs (white and pink), which now have deterioration problems. In this study, the depth and characteristics of the weathering zones that have developed in the white and pink tuffs have been investigated through thin-section studies, X-ray powder diffractometry, methylene blue adsorption tests, major-element analyses, and some index parameters. It has been determined that the feldspar minerals are mechanically fractured due to weathering. The tuffs contain small amounts of clay minerals. An approximately 1-cm-thick silica-rich zone has developed …


Development Of A Basic Gis Database For The Yeşilırmak Watershed Provinces Using Satellite Images And Other Data, Hülya Yildirim, Erhan Alparslan, Mehmet Emi̇n Özel, Ci̇hangi̇r Aydöner, Samuray Eli̇taş, Nalan Jale Di̇van, Mehmet Dağci, Asli Süha Dönertaş Jan 2001

Development Of A Basic Gis Database For The Yeşilırmak Watershed Provinces Using Satellite Images And Other Data, Hülya Yildirim, Erhan Alparslan, Mehmet Emi̇n Özel, Ci̇hangi̇r Aydöner, Samuray Eli̇taş, Nalan Jale Di̇van, Mehmet Dağci, Asli Süha Dönertaş

Turkish Journal of Earth Sciences

Remote-sensing and geographic-information-systems (GIS) techniques were jointly used in this study to establish a GIS database system for the Yeşilırmak watershed provinces, which include Amasya, Tokat, Çorum, Yozgat and Samsun. Composite multicolour images (down to 6 m resolution) from the LANDSAT TM and Indian IRS C/D satellites, land-use/land-cover maps derived from these images, road networks, soil information, digital terrain model, slope and aspect information derived from digital elevation data and meteorological data at province level are the major constituents of this database. A 'project office' has been established with trained personnel at each province centre to effectively use the resultant …


Normal Faults And Extensional Folds Of Southwest Montana And Eastern Idaho, Susanne U. Janecke, J. J. Blankenau, C. J. Vandenburg, B. S. Van Gosen Jan 2001

Normal Faults And Extensional Folds Of Southwest Montana And Eastern Idaho, Susanne U. Janecke, J. J. Blankenau, C. J. Vandenburg, B. S. Van Gosen

Geosciences Faculty Publications

No abstract provided.


Before And After Riparian Management: Sediment And Nutrient Exports From A Small Agricultural Catchment, Western Australia, Lucy Mckergow, David Weaver, I Prosser, R Grayson, A. E.G. Reed Jan 2001

Before And After Riparian Management: Sediment And Nutrient Exports From A Small Agricultural Catchment, Western Australia, Lucy Mckergow, David Weaver, I Prosser, R Grayson, A. E.G. Reed

Conference papers and presentations

Riparian vegetation can trap sediment and nutrients coming from hillslopes and reduce stream bank erosion. This study presents results from a 10 year stream monitoring program in a small agricultural catchment near Albany, Western Australia. In 1996, a 1.6 km stream reach was fenced, planted with eucalyptus species and managed separately from the adjacent paddocks. Stream flow, nutrient and sediment concentration data were collected at the downstream end of the fenced riparian area between 1991 and 2000, so there are data for the “before” and “after” riparian management periods. Suspended sediment concentrations fell dramatically following riparian management; the average event …


Relationships Between Stream Order And Management Priority: A Water Quality Case Study, David Weaver, Adrian Reed, John Grant Jan 2001

Relationships Between Stream Order And Management Priority: A Water Quality Case Study, David Weaver, Adrian Reed, John Grant

Conference papers and presentations

Seagrass, which once dominated the habitat of Oyster Harbour on the south coast of Western Australia has been replaced by macroalgae because of increased nutrient and sediment discharge from the rural dominated catchment. Total Phosphorus (TP), Total Nitrogen (TN), Suspended Sediment (SS) and Electrical Conductivity (EC) concentrations from a catchment – wide (168 sites), event-driven snapshot, water quality monitoring program conducted from 1994 to 1996, were analysed in relation to stream order and published survey data on riparian zone condition. This analysis was performed to examine relationships between stream order, riparian zone condition and water quality, and implications for the …


Evidence Of Different Magnetotail Responses To Small Solar Wind Pressure Pulses Depending On Imf Bz Polarity, Mark B. Moldwin, S. S. Mayerberger, Hamid K. Rassoul, Michael R. Collier, Ronald P. Lepping, James A. Slavin, Adam Szabo Jan 2001

Evidence Of Different Magnetotail Responses To Small Solar Wind Pressure Pulses Depending On Imf Bz Polarity, Mark B. Moldwin, S. S. Mayerberger, Hamid K. Rassoul, Michael R. Collier, Ronald P. Lepping, James A. Slavin, Adam Szabo

Aerospace, Physics, and Space Science Faculty Publications

The response of the magnetotail to small flux rope associated pressure pulses depends on the IMF Bz polarity. Clear and large amplitude magnetotail reverse polarity South-then-North traveling compression regions (SN TCRs) are observed when the pressure pulse is associated with the northward IMF interval of the flux rope. These tail signatures correspond to small-scale (<10 minute duration) pulses of the solar wind dynamic pressure located in front of and within the small-scale flux ropes. Pressure pulses associated with IMF Bz southward are either absent or give rise to smaller amplitude compressions and less systematic lobe Bz rotations. These results suggest that the orientation of the IMF Bz plays a critical role in modulating the magnetotail response to solar wind dynamic pressure pulses.


On The Origin Of Reverse Polarity Tcrs, Mark B. Moldwin, Michael R. Collier, James A. Slavin, Adam Szabo Jan 2001

On The Origin Of Reverse Polarity Tcrs, Mark B. Moldwin, Michael R. Collier, James A. Slavin, Adam Szabo

Aerospace, Physics, and Space Science Faculty Publications

Reverse polarity, or South-then-North (SN) bipolar, traveling compression regions (SN TCRs) are often observed in the Earth's magnetotail lobes. These events have been interpreted as either slowly earthward propagating "proto-plasmoids" during extremely quiet geomagnetic conditions, or due to pressure pulses in the solar wind or magnetosheath compressing the magnetotail. This study presents a survey of 21 IMP 8 observations of SN TCRs and the corresponding solar wind pressure conditions as measured by WIND. We found that solar wind or magnetosheath pressure pulses nicely explain most (17), though not all, of the SN TCR observations. Therefore, it appears that both explanations …


A Sea-Level Lowstand (Devil's Point Event) Recorded In Bahamian Reefs: Comparison With Other Last Interglacial Climate Proxies, Brian White, H. Allen Curran, Mark A. Wilson Jan 2001

A Sea-Level Lowstand (Devil's Point Event) Recorded In Bahamian Reefs: Comparison With Other Last Interglacial Climate Proxies, Brian White, H. Allen Curran, Mark A. Wilson

Geosciences: Faculty Publications

Reprinted from: Benjamin J. Greenstein and Cindy K. Carney (eds.) Proceedings of the 10th Symposium on the Geology of the Bahamas and Other Carbonate Regions: San Salvador, Gerace Research Center


Coastal Effects Of Hurricane Floyd On San Salvador Island, Bahamas, H. Allen Curran, Priscilla Delano, Brian White, Meredith Barrett Jan 2001

Coastal Effects Of Hurricane Floyd On San Salvador Island, Bahamas, H. Allen Curran, Priscilla Delano, Brian White, Meredith Barrett

Geosciences: Faculty Publications

Hurricane Floyd, a Category 4 storm with winds up to I 55 mph, made a close encounter with San Salvador Island on September 13-14, 1999. In addition to inflicting severe damage to homes, tourist facilities, businesses, and infrastructure on the island, the storm also caused considerable beach erosion and coastal modification, mostly on the western and northern coasts. This paper reports and documents with photos the findings of a survey of coastal erosion effects on four areas of the San Salvador coastline: Coast Guard Beach, Rocky Point south to Cockburn Town and Fernandez Bay, South of Sugarloaf toward Grotto Bay, …


Geologic Hazards Associated With Shale Strata And Swelling Clays Within Fayetteville Quadrangle, Washington County, Arkansas, Maria E. King, Jack T. King, Stephen K. Boss Jan 2001

Geologic Hazards Associated With Shale Strata And Swelling Clays Within Fayetteville Quadrangle, Washington County, Arkansas, Maria E. King, Jack T. King, Stephen K. Boss

Journal of the Arkansas Academy of Science

No abstract provided.


Thermodynamic Properties Of Neutron-Rich Matter, Matt Tilley, Bao-An Li Jan 2001

Thermodynamic Properties Of Neutron-Rich Matter, Matt Tilley, Bao-An Li

Journal of the Arkansas Academy of Science

The mechanism of supernova explosion and properties of neutron stars are uniquely determined by the equation of state of neutron-rich matter. Using a phenomenological equation of state within a thermal model, we study thermodynamic properties of neutron-rich matter. In particular, we investigate chemical (diffusive) and mechanical (isothermal) instabilities of neutron-rich matter and their dependence on the nuclear equation of state. Both instabilities are found to be heavily dependent upon the isospin asymmetry, temperature, and density of neutron-rich matter. We show that the boundary of the chemical instability extends farther out into the density-isospin symmetry plane than that of the mechanical …


A Small Look At The Big Picture: Linking Geopotential Height Anomalies To Paleofloods On The Snake River, Idaho And Oregon, Gwendolyn Bernitha Rhodes Jan 2001

A Small Look At The Big Picture: Linking Geopotential Height Anomalies To Paleofloods On The Snake River, Idaho And Oregon, Gwendolyn Bernitha Rhodes

All Master's Theses

A combined paleoflood and flood hydroclimatology study on the Snake River in Idaho and Oregon suggests a link between floods and patters of geopotential height anomalies over the North Pacific Ocean. Examination of the paleoflood record in two 4-m (12 ft) tall terraces along the Hells Canyon reach of the Snake River in Idaho and Oregon shows evidence of at least twenty-two late-Holocene extreme floods that occurred approximately 5,000 years. The ages of paleoflood deposits at these sites fall into two time periods, from 5130 ± 40 to 1960 ± 40 yr BP and from 320 ± 40 yr BP …


Burakin Focus Catchment Report, Mike Clarke Jan 2001

Burakin Focus Catchment Report, Mike Clarke

Natural resources published reports

The Burakin Focus Catchment Project was developed between farmers and Agriculture _ Western Australia. The project was designed to give farmers an understanding of the salinity processes occurring within the Catchment and suggestions on appropriate management.

Work began in the Catchment early in 1999 and was complete at the end of 2000. Intensive hydrological investigations formed the basis of the study, which was complemented by surface water control and revegetation strategies. Agronomic issues associated with sandplain soils were raised by the farmers at the initial meeting and this led to a soil survey to determine the pH status of the …


Farming Systems To Manage Salinity. Farmer Directed Research, Development And Extension. Research Results 2001, Richard Olive Jan 2001

Farming Systems To Manage Salinity. Farmer Directed Research, Development And Extension. Research Results 2001, Richard Olive

Natural resources published reports

More and more of Western Australia's agnicultural lands are becoming saline. Currently it is estimated that about 18 milliion ha of land are affected to a greater or lesser degree by salinity causing production losses estimated at about $70 million a year.

Unless ways are found to halt and reverse the salinisation of land it is estimated that another 4.4 million ha could become saline over the next 50 years.

Grain growers and the Federal Government, through the Grains Research and Development Corporation (GRDC). are investing $12 4 million in R&D across Australia to develop productive solutions to the salinity …


Soilguide (Soil Guide) : A Handbook For Understanding And Managing Agricultural Soils, Geoff Allan Moore Jan 2001

Soilguide (Soil Guide) : A Handbook For Understanding And Managing Agricultural Soils, Geoff Allan Moore

Bulletins 4000 -

This handbook integrates the current knowledge of soils in south-western Australia in a user-friendly form. It describes how to assess which soil properties influence production and land degradation in the agricultural area and summarises management options to remedy or minimise soil limitations. The potential for growing a large range of crops and pastures can be assessed. In particular, the links between soil morphology, soil properties, management and agronomy are emphasised. The manual is designed for use at the paddock scale or for site assessment, but it can also be used at a catchment or regional scale. It is specifically designed …


The Assessment Of Satellite Remote Sensing As A Tool For Determining Sea Surface Temperatures In Nearshore Environments, Fabienne Faskel Jan 2001

The Assessment Of Satellite Remote Sensing As A Tool For Determining Sea Surface Temperatures In Nearshore Environments, Fabienne Faskel

Theses : Honours

The use of satellite remote sensing for environmental management applications has seen a marked increase over the past decade. Remotely sensed data are obtainable for a variety of parameters, such as mineral exploration, species migration, and for determining sea surface temperatures (SSTs). This study examined whether satellite remote sensing is a viable option for determining SSTs in coastal waters, as traditionally this application has only been applied to open-ocean, offshore waters. SSTs in the nearshore waters of Rottnest Island, Western Australia, were determined using in situ temperature loggers and remotely sensed satellite data. Initially the accuracy of the satellite sea …


Hydrogeological Study Of The Dongolocking Reserves, Dumbleyung, Western Australia, Ben Whitfield Jan 2001

Hydrogeological Study Of The Dongolocking Reserves, Dumbleyung, Western Australia, Ben Whitfield

Resource management technical reports

The aims of the hydrogeological study were to assess the characteristics of aquifers within the weathered zone, throughout the Dongolocking Reserves and in the surrounding farmland; provide baseline data on root zone salt store (EM38) and vertical distribution of stored salts (EM38) through the use of ground-based geophysical techniques; identify remnant bush at risk of salinisation; suggest management options to address any observed salinity problems; provide a groundwater monitoring network.


Chronostratigraphy Of The Crp-3 Drillhole, Victoria Land Basin, Antarctica, M. J. Hannah, F. Florindo, David M. Harwood, Christopher R. Fielding, Cape Roberts Science Team Jan 2001

Chronostratigraphy Of The Crp-3 Drillhole, Victoria Land Basin, Antarctica, M. J. Hannah, F. Florindo, David M. Harwood, Christopher R. Fielding, Cape Roberts Science Team

Department of Earth and Atmospheric Sciences: Faculty Publications

An 823 m thick glaciomarine Cenozoic section sitting unconformably on the Lower Devonian Beacon Supergroup was recovered in CRP –3. This paper reviews the chronostratigraphical constraints for the Cenozoic section. Between 3 and 480.27 mbsf 23 unconformity bounded cycles of sediment were recorded. Each unconformity is thought to represent a hiatus of uncertain duration. Four magnetozones have been recognised from the Cenozoic section. The record is complex with several “tiny wiggles” recorded throughout. Biostratigraphical or Sr ages, which could be used to link these magnetozones to the magnetic polarity time scale are restricted to the upper 190 m of sediment. …


Glacial Deposits, Vol. 29, 2000-2001, Department Of Geography-Geology Jan 2001

Glacial Deposits, Vol. 29, 2000-2001, Department Of Geography-Geology

Glacial Deposits

Newsletter of the Department of Geography-Geology


Post-Stagnation Behavior In The Upstream Regions Of Ice Stream C, West Antarctica, Stephen F. Price, R. A. Bindschadler, Christina L. Hulbe, Ian R. Joughin Jan 2001

Post-Stagnation Behavior In The Upstream Regions Of Ice Stream C, West Antarctica, Stephen F. Price, R. A. Bindschadler, Christina L. Hulbe, Ian R. Joughin

Geology Faculty Publications and Presentations

The region where two active tributaries feed into the now stagnant Ice Stream C (ISC), West Antarctica, is thickening. In this region, we observe a correlation between faster ice flow (the tributaries) and elevated topography. We conclude that stagnation of ISC resulted in compression and thickening along the tributaries, eventually forming a "bulge" on the ice-sheet surface. Modern hydraulic potential gradients would divert basal meltwater from ISC to Ice Stream B (ISB). These gradients are primarily controlled by the bulge topography, and so likely formed subsequent to trunk stagnation. As such, we argue against "water piracy" as being the cause …


Sedimentary Cyclicity In Crp Drillcore, Victoria Land Basin, Antarctica, T. R. Naish, P. J. Barrett, G. B. Dunbar, K. J. Woolfe, A. G. Dunn, S. A. Henrys, M. Claps, R. D. Powell, Christopher R. Fielding Jan 2001

Sedimentary Cyclicity In Crp Drillcore, Victoria Land Basin, Antarctica, T. R. Naish, P. J. Barrett, G. B. Dunbar, K. J. Woolfe, A. G. Dunn, S. A. Henrys, M. Claps, R. D. Powell, Christopher R. Fielding

Department of Earth and Atmospheric Sciences: Faculty Publications

The upper 1200 m of pre-Pliocene sediment recovered by Cape Roberts Project (CRP) drilling off the Victoria Land coast of Antarctica between 1997-1999 has been subdivided into 54 unconformity-bound stratigraphic sequences, spanning the period c. 32 to 17 Ma. The sequences are recognised on the basis of the cyclical vertical stacking of their constituent lithofacies, which are enclosed by erosion surfaces produced during the grounding of the advancing ice margin onto the sea floor. Each sequence represents deposition in a range of offshore shelf to coastal glacimarine sedimentary environments during oscillations in the ice margin across the Western Ross Sea …


South West Hydrological Information Package : Understanding And Managing Hydrological Issues On Agricultural Land In The South West Of Western Australia, Peter J. Tille, T W. Mathwin, Richard J. George Dr Jan 2001

South West Hydrological Information Package : Understanding And Managing Hydrological Issues On Agricultural Land In The South West Of Western Australia, Peter J. Tille, T W. Mathwin, Richard J. George Dr

Bulletins 4000 -

This manual reviews current knowledge of the hydrological issues that affect, or are affected by, agriculture in the catchments of the south west of Western Australia.


Wa Soil Erosion Under Investigation, George Richard Dr Jan 2001

Wa Soil Erosion Under Investigation, George Richard Dr

Journal of the Department of Agriculture, Western Australia, Series 4

A survey of soil erosion at 70 sites throughout Western Australia, recently completed as a part of a National Reconnaissance Survey, has shown that erosion is occurring at an unsustainable rate. While still to be compiled into a national publication, Dr Richard George reports on the Western Australian results, and discusses options for management and further investigation.


The Great Plains Natural Resources And Environmental Change Survey Report, D. C. Gosselin, R. Levy, D. Geise Jan 2001

The Great Plains Natural Resources And Environmental Change Survey Report, D. C. Gosselin, R. Levy, D. Geise

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.


Results Of Whole-Rock Organic Geochemical Analyses Of The Crp-3 Drillcore, Victoria Land Basin, Antarctica, Richard M. Kettler Jan 2001

Results Of Whole-Rock Organic Geochemical Analyses Of The Crp-3 Drillcore, Victoria Land Basin, Antarctica, Richard M. Kettler

Department of Earth and Atmospheric Sciences: Faculty Publications

Sediments and rocks recovered in CRP-3 coring operations contain minute amounts of organic matter (average 0.3% TOC). TOC contents and C:N ratios are zoned systematically: those rocks encountered at depths greater than 330 meters below sea floor (mbsf) contain less organic matter and have higher TOC:N ratios (after correcting for inorganic N) than do shallower rocks. The only two samples that have TOC values greater than 1% also contain abundant granule to silt-sized particles of coal. The total sulphur contents of these rocks is very low and indicates either that only small amounts of deposited organic matter were labile, or …


Facies Architecture Of The Crp-3 Drillhole, Victoria Land Basin, Antarctica, Christopher R. Fielding, T. R. Naish, K. J. Woolfe Jan 2001

Facies Architecture Of The Crp-3 Drillhole, Victoria Land Basin, Antarctica, Christopher R. Fielding, T. R. Naish, K. J. Woolfe

Department of Earth and Atmospheric Sciences: Faculty Publications

The Cenozoic Victoria Land Basin (VLB) stratigraphic section penetrated by CRP-3 is mostly of Early Oligocene age. It contains an array of lithofacies comprising fine-grained mudrocks, interlaminated and interbedded mudrocks/sandstones, mud-rich and mud-poor sandstones, conglomerates and diamctites that are together interpreted as the products of shallow marine to possibly non-marine environments of deposition, affected by the periodic advance and retreat of tidewater glaciers. This lithofacies assemblage can be readily rationalised using the facies scheme designed originally for CRP-2/2A, and published previously. The uppermost 330 metres below sea floor (mbsf) shows a cyclical arrangement of lithofacies also similar to that recognised …


Depositional Environments For Strata Cored In Crp-3 (Cape Roberts Project), Victoria Land Basin, Antarctica: Palaeoglaciological And Palaeoclimatological Inferences, R. D. Powell, M. G. Laird, T. R. Naish, Christopher R. Fielding, L. A. Krissek, J.J. M. Van Der Meer Jan 2001

Depositional Environments For Strata Cored In Crp-3 (Cape Roberts Project), Victoria Land Basin, Antarctica: Palaeoglaciological And Palaeoclimatological Inferences, R. D. Powell, M. G. Laird, T. R. Naish, Christopher R. Fielding, L. A. Krissek, J.J. M. Van Der Meer

Department of Earth and Atmospheric Sciences: Faculty Publications

Cape Roberts Project drill core 3 (CRP-3) was obtained from Roberts ridge, a sea-floor high located at 77oS, 12 km offshore from Cape Roberts in western McMurdo Sound, Antarctica. The recovered core is about 939 m long and comprises strata dated as being early Oligocene (possibly latest Eocene) in age, resting unconformably on ~116 m of basement rocks consisting of Palaeozoic Beacon Supergroup sediments. The core includes ten facies commonly occurring in five major associations that are repeated in particular sequences throughout the core and which are interpreted as representing different depositional environments through time. Depositional systems inferred …


Comparison Of Interannual Snowmelt-Onset Dates With Atmospheric Conditions, Sheldon D. Drobot, Mark R. Anderson Jan 2001

Comparison Of Interannual Snowmelt-Onset Dates With Atmospheric Conditions, Sheldon D. Drobot, Mark R. Anderson

Department of Earth and Atmospheric Sciences: Faculty Publications

The snowmelt-onset date represents an important transitional point in the Arctic surface energy balance, when albedo decreases and energy absorption increases rapidly in response to the appearance of liquid water. Interannual variations in snowmelt onset are likely related to large-scale variations in atmospheric circulation, such as described by the Arctic Oscillation (AO). This research therefore examines the relationship between monthly-averaged AO values and mean annual snowmelt-onset dates over Arctic sea ice in 13 regions, from 1979 to 1998. The objective is to statistically relate variations in mean annual regional snowmelt-onset dates to variations in the AO. Additionally, monthly-averaged 500 hPa …


The Onset Of Arctic Sea-Ice Snowmelt As Detected With Passive- And Active-Microwave Remote Sensing, Richard R. Forster, David G. Long, Kenneth C. Jezek, Sheldon D. Drobot, Mark R. Anderson Jan 2001

The Onset Of Arctic Sea-Ice Snowmelt As Detected With Passive- And Active-Microwave Remote Sensing, Richard R. Forster, David G. Long, Kenneth C. Jezek, Sheldon D. Drobot, Mark R. Anderson

Department of Earth and Atmospheric Sciences: Faculty Publications

Daily acquisitions from satellite microwave sensors can be used to observe the spatial and temporal characteristics of the Arctic sea-ice snowmelt onset because the initial presence of liquid water in a dry snowpack causes a dramatic change in the active and passive-microwave response. A daily sequence of backscatter coefficient images from the NASA scatterometer (NSCAT) clearly shows the spatially continuous progression of decreasing backscatter associated with snowmelt onset across the Arctic Ocean during spring 1997. A time series of the active NSCAT backscatter and a scattering index from the passive Special Sensor Microwave/Imager (SSM/I) show similar trends during the time …


Spatial And Temporal Variability In Snowmelt Onset Over Arctic Sea Ice, Mark R. Anderson, Sheldon D. Drobot Jan 2001

Spatial And Temporal Variability In Snowmelt Onset Over Arctic Sea Ice, Mark R. Anderson, Sheldon D. Drobot

Department of Earth and Atmospheric Sciences: Faculty Publications

Climate models suggest surface warming in the Arctic will be rapid and pronounced, implying substantial changes in snowmelt onset are likely. This research therefore examines spatial and temporal variability in passive-microwave derived snowmelt-onset dates over Arctic sea ice. The objectives are to understand better the regional characteristics of snowmelt and to document whether the snowmelt-onset record shows signs of climate change. Snowmelt-onset dates are derived with Scanning Multichannel Microwave Radiometer and Special Sensor Microwave/Imager brightness-temperature data, and they are subsequently stratified into 13 regions to analyze spatial and temporal variability. Results illustrate significant spatial variability in snowmelt onset, with the …