Andreas Münchow

University of Delaware | UDel UD · School of Marine Science and Policy

Petermann Gletscher in North Greenland features the second largest oating ice shelf in the Northern Hemisphere. is paper describes the history of its exploration and presents new ocean and glacier observations. We nd that the oating ice shelf is strongly coupled to the ocean below and to Nares Strait at time scales from tidal to interannual. Our ob...

Time series observations of velocity, salinity, pressure, and ice draft provide estimates of advective fluxes in Nares Strait from 2003 to 2009 at daily to interannual time scales. Velocity and salinity are integrated across the 36 km wide and 350 m deep channel for two distinct multi-year periods of sea ice cover. These observations indicate multi...

Petermann Gletscher, NW Greenland, drains 4% of the Greenland Ice Sheet into Nares Strait. Its floating ice shelf retreated from 81 km to 46 km length during two large calving events in 2010 and 2012. We document changes in the three-dimensional ice shelf structure from 2000 to 2012 using repeated tracks of airborne laser altimetry and ice radio-ec...

Temperature, salinity, and direct velocity observations from northern Baffin Bay are presented from a summer 2003 survey. The data reveal interactions between fresh and cold Arctic waters advected southward along Baffin Island and salty and warm Atlantic waters advected northward along western Greenland. Geostrophic currents estimated from hydrograp...

Over the last 60 years, the perception of the Arctic Ocean has changed from a hostile, sluggish, steady, ice-covered environment with little global impact to an ocean that has become increasingly accessible, apparently rapidly changing, only partly ice-covered, and connected to the global meridional overturning circulation. Our new observations dem...

Humboldt Gletscher is a 100-km wide, slow-moving glacier in north Greenland which holds a 19-cm global sea level equivalent. Humboldt has been the fourth largest contributor to sea level rise since 1972 but the cause of its mass loss has not been elucidated. Multi-beam echo sounding data collected in 2019 indicate a seabed 200 m deeper than previou...

A set of collocated, in situ oceanographic and glaciological measurements from Petermann Gletscher Ice Shelf, Greenland, provides insights into the dynamics of under-ice flow driving basal melting. At a site 16 km seaward of the grounding line within a longitudinal basal channel, two conductivity-temperature (CT) sensors beneath the ice base and a...

From 2014 through 2016 we instrumented ~80 km wide Norske Trough near 78° N latitude that cuts across the 250 km wide shelf from Fram Strait to the coast. Our measurements resolve a ~10 km wide bottom-intensified jet that carries 0.27±0.06 Sv of warm Atlantic water from Fram Strait towards the glaciers off North-East Greenland. Mean shoreward flows...

A rapid, high‐resolution shipboard survey, using a combination of lowered and expendable hydrographic measurements and vessel‐mounted acoustic Doppler current profiler data, provided a unique three‐dimensional view of an Arctic anti‐cyclonic cold‐core eddy. The eddy was situated 50‐km seaward of the Chukchi Sea shelfbreak over the 1,000 m isobath,...

Increasing ocean and air temperatures have contributed to the removal of floating ice shelves from several Greenland outlet glaciers; however, the specific contribution of these external forcings remains poorly understood. Here we use atmospheric, oceanographic and glaciological time series data from the ice shelf of Petermann Gletscher, NW Greenla...

Hydrographic data collected during five summer surveys between 2002 and 2015 reveal that the subsurface ocean near Petermann Gletscher, Greenland warmed by 0.015 +- 0.013°C yr-1. New 2015 - 2016 mooring data from beneath Petermann Gletscher's ice shelf imply a continued warming of 0.025 +- 0.013°C yr-1 with a modest seasonal signal. In 2015 we meas...

Time series observation of sea ice draft and velocity from Nares Strait between 2003 and 2012 provides new insights on the statistical properties of sea ice leaving the Arctic for the Atlantic Oceans. Median ice draft is 0.8 m, but it varies annually from 1.5 m in 2007–2008 to 0.5 m in 2008–2009. Probability density distributions of sea ice draft d...

Petermann Gletscher drains ~4% of the Greenland ice sheet (GrIS) area, with ~80% of its mass loss occurring by basal melting of its ice shelf. We use a high-resolution coupled ocean and sea-ice model with a thermodynamic glacial ice shelf to diagnose ocean-controlled seasonality in basal melting of the Petermann ice shelf. Basal melt rates increase...

Melting of the Greenland Ice Sheet represents a major uncertainty in projecting future rates of global sea-level rise. Much of this uncertainty is related to a lack of knowledge about subsurface ocean hydrographic properties, particularly heat content, how these properties are modified across the continental shelf, and the extent to which the ocean...

Intrusions of Atlantic Water cause basal melting of Greenlands marine terminating glaciers and ice shelves such as that of Petermann Glacier, in northwest Greenland. The fate of the resulting glacial meltwater is largely unknown. It is investigated here, using hydrographic observations collected during a research cruise in Petermann Fjord and adjac...

Two simplified ocean simulations are used to study circulation and transport within Nares Strait. The simulations are similar, except that one included a coupled sea ice model that effectively established a landfast ice cover throughout the simulation year. Comparison between the ocean-only and ocean-ice simulations reveals a systematic change in t...

Over the past several decades, the Beaufort Gyre has experienced changes in sea-ice freshwater accumulation and ocean stratification which has implications for long-range acoustic propagation. In this talk, acoustic propagation from the Canadian Basin to the Alaskan Beaufort Shelf is modeled using measurements of physical oceanography and sea ice....

Petermann Glacier is a ma jor glacier in northern Greenland, maintaining one of the few remaining floating ice tongues in Greenland. Monitoring programs, such as NASA’s Operation IceBridge have surveyed Petermann Glacier over several decades and have found it to be stable in terms of mass balance, velocity and grounding-line position. The future vul...

Petermann Glacier is a major glacier in northern Greenland, maintaining one of the few remaining floating ice tongues in Greenland. Monitoring programs, such as NASA's Operation IceBridge have surveyed Petermann Glacier over several decades and have found it to be stable in terms of mass balance, velocity and grounding-line position. The future vul...

This study discusses geostrophic ocean currents and fluxes through Nares Strait, one of the major straits connecting the Arctic Ocean to the North Atlantic across the Canadian polar shelf. Between 2003 and 2006, instruments were installed on subsea moorings to measure conductivity, temperature, pressure and velocity at high temporal and spatial res...

Nares Strait is a 40-km wide and 500-km long channel to the west of Greenland, that facilitates the exchange of heat and freshwater between the Arctic and Atlantic Oceans. The Canadian Archipelago Throughflow Study and its ongoing International Polar Year extension focus on the dynamics in Nares Strait for the 2003 - 2006 and 2007 - 2009 periods, r...

1] The floating ice shelf of Petermann glacier interacts directly with the ocean and is thought to lose at least 80% of its mass through basal melting. Based on three opportunistic ocean surveys in Petermann Fjord we describe the basic oceanography: the circulation at the fjord mouth, the hydrographic structure beneath the ice shelf, the oceanic he...

On 4 August 2010, about one fifth of the floating ice tongue of Petermann Glacier (also known as ``Petermann Gletscher'') in northwestern Greenland calved (Figure 1). The resulting ``ice island'' had an area approximately 4 times that of Manhattan Island (about 253±17 square kilometers). The ice island garnered much attention from the media, politi...

Petermann Glacier is major outlet glacier that drains 6% of the area of the Greenland Ice Sheet in western North Greenland. It is one of four major outlet glaciers on Greenland with a grounding line substantially below sea level (about 500m) and one of two such glaciers to retain a substantial floating tongue. The floating ice tongue of Petermann g...

1] Nares Strait to the west of Greenland facilitates the exchange of heat and freshwater between the Arctic and Atlantic Oceans. This study focuses on salinity, temperature, and density measurements from Nares Strait from a mooring array deployed from 2003 to 2006. Innovative moorings requiring novel analysis methods measured seawater properties ne...

Nares Strait is a 40-km wide and 500-km long channel to the west of Greenland that facilitates the exchange of heat and freshwater between the Arctic and Atlantic Oceans. The Canadian Archipelago Throughflow Study and its ongoing International Polar Year extension focus on the dynamics in Nares Strait for the 2003/06 and 2007/09 periods, respective...

We analyze hydrographic and current observations of an upwelling center off eastern South America on the Uruguayan coast (∼35S) and downshelf from the Rio de la Plata estuary. Our observations show that the buoyancy-driven subtidal alongshore circulation is modulated by winds. During the winter, strong upwelling-favorable local winds forced the Rio...

During 2003-06, as part of the Arctic Sub-Arctic Ocean Flux (ASOF) experiment, an array of oceansensing instruments was deployed at 80.5N latitude to investigate the flux of seawater from the Arctic Ocean via Nares Strait, the pathway to the west of Greenland. Three-year measurements of current from this experiment provide, for the first time at pe...

Observations have revealed persistent flows of relatively low salinity from the Pacific to the Arctic and from the Arctic to the Atlantic (Melling 2000). It is customary to associate fluxes of fresh-water with these flows of brine, as follows: the fresh-water flux is the volume of fresh water that must be combined with a volume of reference-salinit...

Freshwater delivered as precipitation and runoff to the North Pacific and Arctic oceans returns to the Atlantic principally via the Canadian polar shelf and Fram Strait. It is conveyed as ice or freshened seawater. Here we use detailed ship-based measurements to calculate a snap-shot of volume, freshwater, and tracer fluxes through Nares Strait, a...

The Arctic Ocean is an important link in the global hydrological cycle, storing freshwater and releasing it to the North Atlantic Ocean in a variable fashion as pack ice and freshened seawater. An unknown fraction of this return flow passes through Nares Strait between northern Canada and Greenland. Surveys of ocean current and salinity in Nares St...

1] Regression analysis of historical hydrographic data is used to determine changes in temperature and salinity in Baffin Bay for the time period from 1916 to 2003. We find two distinct sets of changes in the Baffin: First, areas affected by the Atlantic inflow to Baffin Bay show substantial and statistically significant warming trends. In the more...

Copyrighted by American Geophysical Union. Satellite observations of ice motion are combined with model estimates of low-level winds and surface wind stress to provide evidence for atmospheric control of sea-ice motion through Nares Strait, between Ellesmere Island and Greenland, during two periods in 2004. The results suggest that ice flux through...

The Canadian Archipelago constitutes one major pathway of freshwater from the Arctic Ocean into the North-Atlantic. The hypothesized freshwater flux is hypothesized to impact vertical stratification in the ocean and thus the global thermohaline circulation. While this simplification appears reasonable, it involves a number of physical processes all...

Climate change often appears dramatic when one averages the oscillatory system under investigation over short periods of its most extreme positive and negative stages and calls the difference change. While formally correct, the suggested change is often mistaken for a trend especially by the public and those not trained in the delicacies of statist...

The resounding yes may surprise Arctic researchers and old-style oceanographers, but the physics of coastal waters less than 20-m deep has been the subject of intense experimental and theoretical study over the last decade by physical oceanographers. For example, discoveries on the dynamics of (often sediment ladden) freshwater discharges into the...

The impact of buoyant discharge variations on the dynamics of coastal buoyancy-driven currents is studied using a primitive equation numerical model (SPEM5). First, variable discharge is introduced as harmonic fluctuations of the inflow velocity at the tidal (period 12 hours) and subinertial (period 10 days) frequencies. Tidal fluctuations produce...

Shipboard hydrographic and acoustic Doppler current profiler surveys conducted in August 1996 on the New Jersey inner shelf revealed a buoyant intrusion advancing southward along the coast. This buoyant intrusion originated from the Hudson estuary more than 100 km upshelf and appeared as a bulge of less saline water with a sharp across-shelf fronta...

Synoptic velocity and water mass observations obtained in 1993 provide a snapshot of the circulation over the slope of the Chukchi and East Siberian Seas. We describe flow and density fields between the 100-m and 2000-m isobaths >350 km to the north of Siberia near the date line. Strong property gradients on sloping isopycnal surfaces reflect sharp...

Near Point Conception, California, the atmospheric flow separates from the coast and a large wind stress curl results. Direct spatial wind field observations from 20 aircraft overflights in the spring of 1983 suggest that Ekman pumping of on average 4 m day21 contributes to the local dynamics. During strong and persistent upwelling events the curl-...

A three-dimensional data interpolation technique is proposed that efficiently removes tidal currents from spatial velocity surveys. The least squares method extends prior two-dimensional detiding methods to three spatial dimensions using biharmonic splines. Biharmonic splines are fitted to velocity data from acoustic Doppler current profiler (ADCP)...

Subinertial currents on a wide (;100 km), shallow (;20 m), but nevertheless vertically stratified shelf off the Atlantic seaboard of the United States are investigated at spatial scales of about 20 km in the alongshore and 10 km in the across-shore direction. During the summer of 1996 the inner shelf off New Jersey was stratified due to both temper...

During the ice-free summer season in 1995 the authors deployed and subsequently tracked 39 surface drifters to test the hypothesis that the discharge from the Kolyma River forces a buoyancy-driven coastal current from the East Siberian Sea toward Bering Strait. The obser ved mean flow is statistically significant at the 95% level of confidence, but...

During the ice-free summer season in 1995 the authors deployed and subsequently tracked 39 surface drifters to test the hypothesis that the discharge from the Kolyma River forces a buoyancy-driven coastal current from the East Siberian Sea toward Bering Strait. The observed mean flow is statistically significant at the 95% level of confidence, but...

The Santa Barbara Channel off Southern California constitutes a topographically complex channel that is open at both ends. Tidal sea level oscillations are well explained by a north- westward propagating Kelvin wave. Tidal currents vary at a multitude of topographic and temporal scales and cannot be explained by linear Kelvin wave dynamics alone. T...

We extend and interpret acoustic Doppler current profiler and conductivity-temperature-depth data collected in the summer of 1993 over Barrow Canyon in order to implement a high resolution (1.5 to 5 km) model of the Beaufort and Chukchi Seas. This paper addresses physical processes relevant to the Barrow Canyon region using common dynamica...

Analyses of data from three shipborne surveys describe the quasi-synoptic density and velocity fields near Barrow Canyon, Alaska. The canyon parallels the northwestern coast of Alaska and contains three different water masses. These are 1) warm and fresh Alaskan coastal waters that originate from the Bering Strait; 2) cold and moderately salty wate...

A towed acoustic Doppler current profiler (ADCP) system was tested. The instrument was deployed from ships of opportunity and towed at depths between 5 and 25 m. The towed system carries upward- and downward-looking ADCPs. The instrument platform is stable in most operating conditions at ship speeds up to 4.5 m s−1. Large discrepancies are found, h...

In May and June of 1990 we explored the hydrographic variability of the Delaware Estuary and the adjacent inner shelf with shipboard instruments. We found significant three-dimensional density variability both within the estuary and on the shelf. We found weak vertical stratification but strong transverse variability within the estuary, with denser...

The outflow of buoyant waters from major estuaries affects the dynamics of inner continental shelves profoundly as lateral density gradients force an alongshore current. Often the Coriolis force causes the outflow to remain trapped near the coast. We observed one such current, the Delaware Coastal Current, on the inner shelf near the Delaware Estua...

Local winds and lateral buoyancy fluxes from estuaries constitute two major forcing mechanisms on the inner continental shelf of the Mid Atlantic Bight on the eastern seaboard of the U.S.A. We report observations of the resulting coastal current that suggest a linear superposition of the wind and buoyancy forced motions. This current, which we term...

The propagation of tides from the coastal ocean into shallow estuarine waters often produces characteristic nonlinearly induced asymmetries of velocity and water level in time series. Until recently (Aubrey and Speer, 1985) a sound physical understanding of related phenomena has been difficult to obtain as flow field data are rare. Numerical studie...

As part of a comprehensive study of inner shelf dynamics in the vicinity of a major estuary, we test the performance of a shipboard acoustic Doppler current profiler (ADCP). We compare velocities from the ADCP with those from current meters located 6 and 10 m below the surface in water shallower than 30 m. We find the ADCP suitable to estimate subt...

We analysed the tidal content of current time series from 53 current meters at 31 mooring locations on the inner continental shelf in the vicinity of Delaware Bay, U.S.A. We distinguish between an astronomically forced short period flow field at diurnal and semi-diurnal frequencies and a nonlinearly generated long period tidal flow field. The latte...

Photocopy. Thesis (M.S.)--University of Delaware, 1989. Principal faculty adviser: Richard W. Garvine, Department of Marine Studies. Includes bibliographical references (leaves 75-76).

Awards: N00014-98-1-0066 and N00014-98-1-0396 (AASERT) LONG TERM GOALS Understanding across-shelf exchange and shelf dynamics due to wind and buoyancy forcing. OBJECTIVES The main objective of this project is to describe and physically explain the dominant processes active within the wide Canadian Mackenzie Canyon prior to the onset of winter freez...

Baffin Bay between Greenland and Arctic Canada contains a deep (>2000-m), isolated basin that is connected to the North Atlantic and Arctic Oceans only above 600-m. The isolation of its deep waters makes it an ideal location to monitor change. The Beford Institute of Oceanography assembled hydrographic data for this location from 1924 through 1997...

Petermann Glacier at 81 N latitude is a major outlet glacier adjacent to Nares Strait. It terminates in a long (70 km), narrow (16 km) and thin (50 m) floating tongue and has a grounding line more than 500 m below sea level. A calving event in 2010 reduced the floating area by 25% and produced a single 240 km2 ice island currently moving south in N...

Intellectual Merit This proposal seeks support to test the hypothesis that the dynamics of Nares Strait is in a state of transition as the season of landfast ice cover diminishes. To do so, we propose to analyze a comprehensive 6-year data set from an array of moored ocean current, salinity, temperature, sea level, and subsurface pressure sensors,...