Open Water Cover Research Articles

Increasing fluctuations in the Arctic summer sea ice cover are expected with future global warming

The loss of Arctic sea ice (ASI) represents a major transformation in the Arctic region, impacting regional and global climate, ecosystems, and socio-economic structures. Observational and reanalysis data have consistently shown a notable shift in polar environmental conditions over recent decades, marked by a substantial reduction in the ASI area and a rise in the variability in its coverage and distribution. Utilizing data from the latest Coupled Model Intercomparison Project phase, our study reveals a consistent pattern highlighting a fundamental shift in ASI dynamics preceding total loss. We observe increasing fluctuations in the September ASI area as the threshold for an ice-free Arctic is approached across various scenarios and models. This pattern is particularly concentrated in the Central Arctic (CA) sub-region. Spatial analyses reveal increasing variance along the CA’s northern coastlines, accompanied by a substantial increase in open water coverage, underscoring the shift from stable to highly variable ice conditions in this region. Additionally, our findings suggest a potential link between increased ASI fluctuations and variability in surface wind speeds. These specific results underscore the urgency of multidisciplinary approaches in addressing the challenges posed by ASI variability, with implications for marine ecosystems, Indigenous communities, and navigational safety.

Secretive marsh bird occupancy across a spectrum of hydroelectric reservoir management in western montane Canada

AbstractDam construction projects have created opportunities for water security, targeted flood protection, and energy production but at the cost of increasing anthropogenic pressure on affected aquatic ecosystems. Wetland ecosystems are often among the most vulnerable, as underlying hydrological regimes influence overall wetland structure and function. Marsh bird species are wetland and riparian habitat specialists, many of which are experiencing population declines across North America. We examined how the alteration of hydrological regimes for generating hydroelectric power affected the occurrence of secretive marsh bird species in the western montane region of British Columbia, Canada. We established survey stations in wetlands across 2 regions, the West Kootenay and the Columbia Wetlands, sampling across a spectrum of hydrological regimes and other potentially relevant factors. At each station, we assessed wetland occupancy during the breeding season using broadcast‐callback surveys focused on 5 secretive marsh bird species: American bittern (Botaurus lentiginosus), American coot (Fulica americana), pied‐billed grebe (Podilymbus podiceps), sora (Porzana carolina), and Virginia rail (Rallus limicola). Additionally, we measured vegetation structure and the proximity and size of nearby water bodies for each survey station. We then used occupancy models to assess important correlates behind wetland occupancy for these marsh bird species, considering water management operations, regional differences, and local‐ and landscape‐level wetland characteristics. Secretive marsh bird species were more likely to occupy wetlands in areas with less frequently altered hydrological regimes. Occupancy models highlighted local‐ and landscape‐level characteristics as important correlates for wetland occupancy by marsh birds. Wetlands with frequently altered hydrological regimes had more open water cover and less tall vegetation present, conditions that were negatively associated with occupancy. Altered wetlands in this study were farther from the next nearest wetland, which was also negatively associated with occupancy. We suggest reservoir management is altering vegetation communities within these wetlands, indirectly promoting lower occupancy of secretive marsh bird species.

Intertidal wetland vegetation dynamics under rising sea levels

Intertidal wetlands have historically been in decline and are increasingly at risk due to climate change, particularly sea level rise (SLR). Different intertidal wetland communities can adapt to SLR via lateral upslope retreat to higher ground, capture and accumulation of allochthonous sediment, and/or organic accretion. In this paper, a case study is presented to assess the impact of the overall sediment accretion rate (i.e. allochthonous and organic accumulation) versus possible SLR rates on wetland species composition. Initially, an eco-hydraulic calculation method is developed to estimate existing spatial and temporal tidal inundation statistics of saltmarsh species at a Ramsar listed wetland on the south-east coast of New South Wales, Australia. SLR and accretion scenarios were then tested using high resolution hydrodynamic models to predict future saltmarsh species composition based on the eco-hydraulic calculation method. Saltmarsh species composition and extents were found to persist if sea levels continue to rise at present-day rates, as observed rates of SLR are similar. However, if the SLR rate accelerates beyond the accretion ability of the wetland, a significant shift in species composition and an increase in open water coverage was predicted. These results indicate that the current rate of sediment capture by wetland species, and the subsequent rate of elevation change, will need to increase significantly to adapt with projected future rates of SLR.

Watershed influences on mercury in tributaries to Lake Ontario.

Mercury (Hg) concentrations and speciation were measured in nine tributaries to Lake Ontario as part of two independent field-sampling programs. Among the study tributaries, mean total Hg (THg) concentrations ranged from 0.9 to 2.6 ng/L; mean dissolved Hg (THgD) ranged from 0.5 to 1.5 ng/L; mean particulate Hg (THgP) ranged from 0.3 to 2.0 ng/L; and mean methylmercury (MeHg) ranged from 0.06 to 0.14 ng/L. Watershed land cover, total suspended solids (TSS), and dissolved organic carbon (DOC) were evaluated as potential controls of tributary Hg. Significant relationships between THgD and DOC were limited, whereas significant relationships between THgP and TSS were common across watersheds. Total suspended solids was strongly correlated with the percentage of agricultural land in watersheds. Particle enrichment of Hg (mass Hg/mass TSS) was highly variable, but distinctly higher in US tributaries likely due to higher TSS in Canadian tributaries associated with higher urban and agricultural land cover. MeHg was largely associated with the aqueous phase, and MeHg as a fraction of THg was positively correlated to percent open water coverage in the watershed. Wetland cover was positively correlated to THg and MeHg concentrations, while urban land cover was only related to higher THgP.

Sympatric Ixodes-tick species: pattern of distribution and pathogen transmission within wild rodent populations

The generalist tick Ixodes ricinus is the most important vector for tick-borne pathogens (TBP), including Borrelia burgdorferi sensu lato, in Europe. However, the involvement of other sympatric Ixodes ticks, such as the specialist vole tick I. trianguliceps, in the enzootic circulations of TBP remains unclear. We studied the distribution of I. ricinus and I. trianguliceps in Central Finland and estimated the TBP infection likelihood in the most common rodent host in relation with the abundance of the two tick species. Ixodes trianguliceps was encountered in all 16 study sites whereas I. ricinus was frequently observed only at a quarter of the study sites. The abundance of I. ricinus was positively associated with open water coverage and human population density around the study sites. Borrelia burgdorferi s. l.-infected rodents were found only in sites where I. ricinus was abundant, whereas the occurrence of other TBP was independent of I. ricinus presence. These results suggest that I. trianguliceps is not sufficient, at least alone, in maintaining the circulation of B. burgdorferi s. l. in wild hosts. In addition, anthropogenic factors might affect the distribution of I. ricinus ticks and, hence, their pathogens, thus shaping the landscape of tick-borne disease risk for humans.

Energetic implications of floodplain wetland restoration strategies for waterfowl

Modifications of the Illinois River and associated tributaries have resulted in altered hydrologic cycles and persistent river‐floodplain connections during the growing season that frequently impede the establishment of hydrophytic vegetation and have reduced value for migratory waterfowl and other waterbirds. To help guide floodplain restoration, we compared energetic carrying capacity for waterfowl in two wetland complexes along the Illinois River under different management regimes during 2012–2015. The south pool of Chautauqua National Wildlife Refuge (CNWR) was seasonally flooded due to a partial river connection and managed for moist‐soil vegetation. Emiquon Preserve was hydrologically isolated from the Illinois River by a high‐elevation levee and managed as a semipermanently flooded emergent marsh. Semipermanent emergent marsh management at Emiquon Preserve produced 5,495 energetic use‐days (EUD)/ha for waterfowl and other waterbirds across wetland cover types and years, and seasonal moist‐soil management at CNWR produced 6,199 EUD/ha in one of 4 years. At Emiquon Preserve, the aquatic bed cover type produced 9,660 EUD/ha, followed by 5,261 EUD/ha in moist‐soil, 1,398 EUD/ha in persistent emergent, 1,185 EUD/ha in hemi‐marsh, and 12 EUD/ha in open water cover types. At CNWR, the annual grass and sedge cover type produced 7,031 EUD/ha, followed by 5,618 EUD/ha in annual broadleaf and 1,305 EUD/ha in perennial grass cover types. Restoration of floodplain wetlands in isolation from frequent flood pulses during the growing season can produce hemi‐marsh and aquatic bed vegetation communities that provide high‐quality habitat for waterfowl and which have been mostly eliminated from large river systems in the Midwest, U.S.A.

Skillful spring forecasts of September Arctic sea ice extent using passive microwave sea ice observations

AbstractIn this study, we demonstrate skillful spring forecasts of detrended September Arctic sea ice extent using passive microwave observations of sea ice concentration (SIC) and melt onset (MO). We compare these to forecasts produced using data from a sophisticated melt pond model, and find similar to higher skill values, where the forecast skill is calculated relative to linear trend persistence. The MO forecasts shows the highest skill in March–May, while the SIC forecasts produce the highest skill in June–August, especially when the forecasts are evaluated over recent years (since 2008). The high MO forecast skill in early spring appears to be driven primarily by the presence and timing of open water anomalies, while the high SIC forecast skill appears to be driven by both open water and surface melt processes. Spatial maps of detrended anomalies highlight the drivers of the different forecasts, and enable us to understand regions of predictive importance. Correctly capturing sea ice state anomalies, along with changes in open water coverage appear to be key processes in skillfully forecasting summer Arctic sea ice.

Conversion of tundra to exposed peat habitat by snow geese (Chen caerulescens caerulescens) and Ross’s geese (C. rossii) in the central Canadian Arctic

The region south of Queen Maud Gulf in Canada’s central Arctic now annually harbors several million nesting and non-breeding Ross’s (Chen rossii) and lesser snow geese (C. caerulescens caerulescens). Here, and in other Arctic and Subarctic areas, abundant goose populations have been demonstrated to have impacted biomass and composition of vegetative communities. We applied the classification scheme that Didiuk and Ferguson (Land cover mapping of Queen Maud Gulf Migratory Bird Sanctuary, Nunavut. Environment Canada, Ottawa, 2005) used on 1986–1992 Landsat Imagery to produce a habitat map for 2011 of the eastern portion of the Queen Maud Gulf Bird Migratory Bird Sanctuary (QMGMBS). We used a Geographic Information System for change detection between 1988 and 2011 and found a > fivefold increase in area of exposed peat habitat from 269 to 1373 km2 in our 36,370 km2 study area. About 323 km2 (24) % of the area classified as exposed peat in 2011 was previously wet sedge meadow, a preferred feeding habitat of geese, and which declined from 2856 to 1488 km2 (−48 %) in our study area. Combined open water categories declined from 9688 to 7960 km2 (−18 %), suggesting that some of the reduction in wet sedge meadow could have been caused by drawdown. However, of the 1981 km2 of open water that was lost between 1988 and 2011, only 142 km2 (7 %) was classified as exposed peat and 250 km2 (13 %) as active deposits, while 171 km2 (9 %) was classified as wet sedge meadow. Of the remaining open water coverage that was lost, 118 km2 (6 %) was classified as hummock or graminoid tundra, 459 km2 (23 %) as moss-lichen or lichen-heath tundra, and 764 km2 (39 %) as low shrub tundra/shrub thicket. Approximately 562 km2 (41 %) of exposed peat in 2011 was formerly moss-lichen and lichen-heath tundra, upland habitats commonly used by nesting snow geese and Ross’s geese. By 2011, the proportion of ground covered by exposed peat habitat surrounding the four largest known colonies of light geese, all in the eastern half of QMGMBS, was strongly linked to the amount of previously vegetated habitat (i.e., potential exposed peat), and was inversely related to distance from colony perimeters. About 50 % of the spatial variance in coverage by exposed peat was explained by nearness to nesting by large concentrations of light geese. While some increase in exposed peat was likely a result of drier conditions in 2011 compared to 1988, spatial patterns of habitat change suggest that much of the increase in exposed peat was likely a result of intensive foraging in wet sedge meadow habitat and nest-building activities in tundra habitats by high densities of snow geese and Ross’s geese. Of the 269 km2 of exposed peat originally identified in 1988, only 55 km2 of it was still classified as exposed peat in 2011, but detailed ground studies will be required to determine at what rate exposed peat habitats revert back to wet sedge meadow and other vegetated tundra. We recommend comparison of habitat changes in areas with and without large populations of lesser snow geese and Ross’s geese to better assess changes caused by geese in relation to any change that may result from changes in hydrology over time.

King Rail (Rallus elegans) Nesting and Brood-Rearing Ecology in a Managed Wetland in Oklahoma, USA

Abstract. The King Rail (Rallus elegans) is a secretive marsh bird of conservation concern. Reproductive success is thought to be a limiting factor for the inland migratory population. Reproductive effort of King Rails was studied in southeastern Oklahoma, USA, from 2010–2012 using surveys, radio-telemetry, nest searching and brood observations. During 2011–2012, 27–29 King Rail territories were documented. Ten nests were located between the first week in April and the first week in July with a mean clutch size of 10.3 (SE = 0.80). Water depth at nests was shallow (< 15 cm), and nest sites were in locations with more visual obstruction, more microtopographic variation, and more woody stems, while open water cover was less than at random sites. Nine broods were followed and were found to use rearing sites that were in deeper water and had a greater percent of tall emergent vegetation and more woody vegetation than random sites. Brood size dropped from an average of nine to two chicks by the second week. We...

Regional melt-pond fraction and albedo of thin Arctic first-year drift ice in late summer

Abstract. The paper presents a case study of the regional (≈150 km) morphological and optical properties of a relatively thin, 70–90 cm modal thickness, first-year Arctic sea ice pack in an advanced stage of melt. The study combines in situ broadband albedo measurements representative of the four main surface types (bare ice, dark melt ponds, bright melt ponds and open water) and images acquired by a helicopter-borne camera system during ice-survey flights. The data were collected during the 8-day ICE12 drift experiment carried out by the Norwegian Polar Institute in the Arctic, north of Svalbard at 82.3° N, from 26 July to 3 August 2012. A set of &gt; 10 000 classified images covering about 28 km2 revealed a homogeneous melt across the study area with melt-pond coverage of ≈ 0.29 and open-water fraction of ≈ 0.11. A decrease in pond fractions observed in the 30 km marginal ice zone (MIZ) occurred in parallel with an increase in open-water coverage. The moving block bootstrap technique applied to sequences of classified sea-ice images and albedo of the four surface types yielded a regional albedo estimate of 0.37 (0.35; 0.40) and regional sea-ice albedo of 0.44 (0.42; 0.46). Random sampling from the set of classified images allowed assessment of the aggregate scale of at least 0.7 km2 for the study area. For the current setup configuration it implies a minimum set of 300 images to process in order to gain adequate statistics on the state of the ice cover. Variance analysis also emphasized the importance of longer series of in situ albedo measurements conducted for each surface type when performing regional upscaling. The uncertainty in the mean estimates of surface type albedo from in situ measurements contributed up to 95% of the variance of the estimated regional albedo, with the remaining variance resulting from the spatial inhomogeneity of sea-ice cover.

Evaluation of the Interactive Multisensor Snow and Ice Mapping System (IMS) for monitoring sea ice phenology

We present an evaluation of the Interactive Multisensor Snow and Ice Mapping System (IMS) for monitoring northern hemisphere sea ice phenology. Analysts utilize a variety of datasets to manually derive the daily extent of snow, ice, water and land, available at both 24 and 4km. The 4km IMS product was assessed for 2004–2008 against several previously established melt/freeze algorithms using Scatterometer Image Reconstruction (SIR) SeaWinds/QuikSCAT (QuikSCAT) backscatter (σ°), Advanced Microwave Scanning Radiometer for the Earth Observing System (AMSR-E) brightness temperature (TB) measurements, data from the Special Sensor Microwave/Image data (SSM/I) and sea ice concentrations derived from DMSP Special Sensor Microwave/Imager–Special Sensor Microwave Imager Sounder (SSMI–SSMIS) data (NASATeam dataset). The resolution possible with the 4km IMS product allows for better spatial representation of sea ice along the coastlines, the ice edges and in the narrow channels of the Canadian Arctic Archipelago as compared to the microwave products. IMS detects open water earlier and freeze onset later than the automated microwave products, and also allows for the detection of opening, and the subsequent closing, of leads that the other datasets are unable to detect. Using RADARSAT-1 imagery for evaluation, IMS is shown to outperform the other datasets for the timing and extent of the first open water detection. IMS identified between 17 and 53% greater open water coverage than the other datasets in the narrow channels of the Northwest Passage (Barrow Strait). In order to further the use of IMS for sea ice applications, we derived two new spatial datasets using the full record of IMS data (4km: 2004–present, 24km: 1997–present): melt duration to open water (duration from melt onset detected with SSM/I passive microwave until open water detected by IMS) and first year ice cover duration (duration from freeze onset until open water, both detected by IMS).

Remote-sensing evaluation of the relationship between urban heat islands and urban biophysical descriptors in Jinan, China

Global warming and climate change have gained more and more attention because the global mean surface temperature has increased since the late 19th century. With the progress of rapid urbanization, Jinan city has witnessed a significant urban thermal environment change. To investigate the relationship between urban heat islands and urban biophysical descriptors, the city’s biophysical properties along with land surface temperature (LST) in 1992 and 2011 were retrieved from the Landsat TM images. Additionally, three thematic indices were employed to extract the features of the impervious surface, water, and vegetation, respectively. The correlation and spatial overlay of these land surface features were then analyzed. The results show that the Jinan region has witnessed very fast urban sprawl. The total impervious surface area of the region in 2011 was 134.7% more than that in 1992. This increase significantly reduced the vegetation and open water coverage in the urban area. Simultaneously, the expansion of impervious surfaces was accompanied by an increased urban heat island (UHI) ratio index, which increased from 0.43 in 1992 to 0.55 in 2011, showing that the UHI in Jinan has developed from a weak level to a significant level over the 19-year period. The quantitative analysis between LST and indices revealed that impervious surfaces have a positive exponential relationship with LST, while the water and vegetation are both negatively correlated with temperature. A multifactor analysis also indicated that the contribution of impervious surfaces to the LST could equal or even exceed that of the sum of vegetation and water.

Seroepidemiology ofCoxiella burnetiiin Wild White-Tailed Deer (Odocoileus virginianus) in New York, United States

Coxiella burnetii is an environmentally resistant bacterium that has been reported in wildlife populations. Frequent contact on pasture between white-tailed deer (Odocoileus virginianus) and cattle has been reported by farmers in the Northeast U.S., and transmission of C. burnetii is thought to occur between wild deer and domestic livestock such as cows, sheep, and goats. Blood samples were collected from white-tailed deer throughout New York State in 2009 and 2010 and examined for anti-C. burnetii phase II antibodies via indirect microimmunofluorescence assays. Exploratory spatial cluster analysis revealed a lack of significant clustering of C. burnetii-seropositive deer. Logistic regression analysis revealed a significant association between the C. burnetii serostatus of deer and sex, percent agriculture, shrub, and forest cover, and townships with more than 10 bovine herds. A lack of significant association was revealed between the serostatus of deer and the year of sampling, soil type, percent wetland and open water cover, total annual precipitation, and townships with more than two sheep or goat herds. Because four different land cover types were associated with a higher probability of C. burnetii seropositivity, it is likely that land cover is not a discriminating factor in C. burnetii exposure. This is probably because C. burnetii environmental contamination is widespread and not localized to certain cover types. The social behavior of male deer may contribute to the lack of spatial clustering. Bucks typically travel over greater distances, which leads to a greater variety of encountered environments and a greater chance for exposure to C. burnetii. Because increasing agricultural land cover and townships with greater than 10 bovine herds are associated with an increased probability of diagnosing a seropositive deer, it appears likely that transmission of C. burnetii between domestic livestock and white-tailed deer may occur.

A Geographic Model to Assess and Limit Cumulative Ecological Degradation from Marcellus Shale Exploitation in New York, USA

Davis, J. B., and G. R. Robinson. 2012. A geographic model to assess and limit cumulative ecological degradation from Marcellus Shale exploitation in New York, USA. Ecology and Society 17(2): 25. https://doi.org/10.5751/ES-04822-170225

Wintertime CO2fluxes in an Arctic polynya using eddy covariance: Evidence for enhanced air-sea gas transfer during ice formation

[1] Between Nov. 1 2007 and Jan. 31 2008, we calculated the air-sea flux of CO2, sensible heat, and water vapor in an Arctic polynya system (Amundsen Gulf, Canada) using eddy covariance equipment deployed on the research icebreaker CCGS Amundsen. During this time period, Amundsen Gulf was a dynamic sea ice environment composed primarily of first year ice with open water coverage varying between 1–14%. In all cases where measurements were influenced by open water we measured CO2 fluxes that were 1–2 orders of magnitude higher than those expected under similar conditions in the open ocean. Fluxes were typically directed toward the water surface with a mean flux of −4.88 μmol m−2 s−1 and a maximum of −27.95 μmol m−2 s−1. One case of rapid outgassing (mean value +2.10 μmol m−2 s−1) was also observed. The consistent patten of enhanced gas exchange over open water allows us to hypothesize that high water-side turbulence is the main cause of these events. Modification of the physical and chemical properties of the surface seawater by cooling and brine rejection may also play a role. A rough calculation using an estimate of open water coverage suggests that the contribution of these events to the annual regional air-sea CO2 exchange budget may make the winter months as important as the open water months. Although high, the uptake of CO2 fits within mixed layer dissolved inorganic carbon budgets derived for the region by other investigators.

Shortwave broadband black-sky surface albedo estimation for Arctic sea ice using passive microwave radiometer data

[1] A new remote sensing method to estimate the optical broadband black-sky surface albedo using passive microwave radiometer data has been developed. In this research, the Advanced Very High Resolution Radiometer (AVHRR) based shortwave broadband black-sky albedos processed using the algorithms of the new surface broadband albedo CM-SAF product SAL, and the Advanced Microwave Scanning Radiometer (AMSR-E) microwave data from the National Snow and Ice Data Center, Boulder, Colorado, have been employed. To analyze the correspondence between AVHRR-based optical albedo and microwave brightness temperature, AMSR-E frequencies of 6.9, 18.7, and 36.5 GHz have been tested by fitting a third-degree polynomial curve to the SAL albedo and the AMSR-E data points. The best correlation occurs in 6.9 GHz vertical polarization brightness temperature (R2 = 0.92). To illustrate and compare the spatial variabilities of the SAL and AMSR-E albedos of the sea ice during the melting and refreezing period, maps of 13 weeks have been prepared of both albedos from June to August 2007. The albedo time series from AMSR-E and AVHRR data are calculated for the combined sea ice and open water cover for the Northern Hemisphere as a whole, and for six specific sea ice regions: the Arctic Ocean, the Kara and Barents Seas, the Greenland Sea, the Labrador Sea, Hudson Bay, and the Canadian Archipelago. The standard errors between the optical and passive microwave estimates varied from about 0.001 (Greenland Sea) to 0.04 (Canadian Archipelago) being 0.013 on the average in absolute units. The relative standard errors are then smaller than 5% in most of the regions.

Using ALOS/PALSAR and RADARSAT-2 to Map Land Cover and Seasonal Inundation in the Brazilian Pantanal

The Brazilian Pantanal is a large continuous tropical wetland with large biodiversity and many threatened habitats. The interplay between the distribution of vegetation, the hydrology, the climate and the geomorphology nourishes and sustains the large diversity of flora and fauna in this wetland, but it is poorly understood at the scale of the entire Pantanal. This study uses multi-temporal L-band ALOS/PALSAR and C-band RADARSAT-2 data to map ecosystems and create spatial-temporal maps of flood dynamics in the Brazilian Pantanal. First, an understanding of the backscattering characteristics of floodable and non-floodable habitats was developed. Second, a Level 1 object-based image analysis (OBIA) classification defining Forest, Savanna, Grasslands/Agriculture, Aquatic Vegetation and Open Water cover types was achieved with accuracy results of 81%. A Level 2 classification separating Flooded from Non-Flooded regions for five temporal periods over one year was also accomplished, showing the interannual variability among sub-regions in the Pantanal. Cross-sensor, multi-temporal SAR data was found to be useful in mapping both land cover and flood patterns in wetland areas. The generated maps will be a valuable asset for defining habitats required to conserve the Pantanal biodiversity and to mitigate the impacts of human development in the region.

Tracking palustrine water seasonal and annual variability in agricultural wetland landscapes using Landsat from 1997 to 2005

AbstractWetlands densely populate the ecoregion transecting the center of the Prairie Pothole Region (PPR) known as the Missouri Coteau and epicenter to the most productive waterfowl‐breeding habitat in North America. These palustrine, depressional basin waters vacillate with regional drought and deluge, so surface water fluctuations over time modulate wetland productivity, habitat, and water quality functions. Models predict formidable effects of climate change on glacial basin surface waters, yet large‐scale, long‐term observation data are lacking to compare against predicted changes. Current, optical‐based water detection models do not delineate marsh vegetation from shallow, turbid, high‐chlorophyll waters common to the region. We developed a palustrine wetland spectral model for tracking open surface waters using Landsat imagery, which we evaluated for a 2500 km2 landscape that estimates seasonal and annual open water variability for thousands of individual wetlands in the Missouri Coteau ecoregion. Detection accuracy of 96% was achieved for water bodies greater than a half‐pixel in size. We identified shifts in the distribution of water permanence classes within and between years for waters emerging in spring, mid‐summer, and late summer from 1997 to 2005 and identified a maximum of 19 047 basins with open water (12% of the landscape) populating 2500 km2. For the 2005 growing season, we observed only 8757 basins with open water (6% of the landscape) for the same area. Declines were greatest for water bodies detected only in spring, suggesting a loss of those wetlands functioning to recharge groundwater stores early in the season and a high sensitivity to observed reductions in snowfall. If landscape factors driving open water coverage and wetland density are similar for the entire Missouri Coteau, we estimate the number of basins containing at least a pixel of water for this region declined from 577 600 to 266 000 between 1997 and 2005.

Sea ice concentration estimates from satellite passive microwave radiometry and openings from SAR ice motion

Openings in the Arctic Ocean ice cover from small‐scale sea ice motion fields are compared with open water fractions retrieved from satellite passive microwave observations. We find very little agreement between the results. Passive microwave retrieval algorithms seem to be insensitive to small areas of open‐water in winter leads. Variability in the passive microwave retrievals is mostly due to anomalous and persistent regions of lower ice concentration where no openings are found. Between January and April of 1998, openings cover ∼0.3 ± 0.1% of the total area within the perennial ice zone. This is smaller, in one instance ten times, than the open water fraction from the passive microwave retrievals. Previous bounds of open water coverage of the ice cover imposed on climate simulations based on uncertainties in passive microwave retrievals (±4 − 7%) are too high and the over‐estimated open water fraction on model results should be re‐examined.

Airborne observations of summertime surface features and their effect on surface albedo during FIRE/SHEBA

Aircraft observations of the arctic surface were obtained during the recent Surface Heat Budget of the Arctic Ocean (SHEBA) and FIRE Arctic Clouds Experiment. A series of images were created from a downward looking video camera that was mounted on the underside of a research aircraft as it flew in the vicinity of the SHEBA camp, which drifted with the pack ice in the Beaufort and eastern Chukchi Seas. These data are processed to determine the distribution of melt ponds and open water during five flights in July 1998. Melt pond and open water coverage vary between 25–34% and 5–9%, respectively. Coincident observations of albedo derived from upward and downward looking broadband shortwave radiometers indicate that the albedo decreased through July until the last week, when the albedo began to rise. Pond fraction was observed to vary inversely with albedo through July. By relating the areal coverage of the surface features to the observed surface albedo, mean albedos of 0.26, 0.07, and 0.60 are found for melt ponds, open water, and pack ice, respectively.