Computing resources donated by volunteers have generated the first superensemble of regional climate model results, in which the Hadley Centre Regional Model, version 3P (HadRM3P), and Hadley Centre Atmosphere Model, version 3P (HadAM3P), were implemented for the western United States at 25-km resolution. Over 136,000 valid and complete 1-yr runs...
General circulation models (GCMs) predict that the global hydrological cycle will change in response to anthropogenic warming. However, these predictions remain uncertain, in particular, for precipitation (Intergovernmental Panel on Climate Change, 2013, https://doi .org/10.1017/CB09781107415324.004). Held and Soden (2006, https://doi.org/10.1175/JCLI3990.1) suggest that as lower tropospheric water vapor concentration increases in a...
Lateral stirring is a basic oceanographic phenomenon affecting the distribution of physical, chemical, and biological fields. Eddy stirring at scales on the order of 100 km (the mesoscale) is fairly well understood and explicitly represented in modern eddy-resolving numerical models of global ocean circulation. The same cannot be said for...
Climate models predict a gradual weakening of the North Atlantic meridional overturning circulation (MOC) during the twenty-first century due to increasing levels of greenhouse gas concentrations in the atmosphere. Using an ensemble of 16 different coupled climate models performed for the Fourth Assessment Report (AR4) of the Intergovernmental Panel on...
This study investigates the exchange of momentum between the atmosphere and ocean using data collected from four oceanic field experiments. Direct covariance estimates of momentum fluxes were collected in all four experiments and wind profiles were collected during three of them. The objective of the investigation is to improve parameterizations...
Full Text:
: On the exchange of momentum over the open ocean. J. Phys. Oceanogr.,
43, 1589–1610, doi:10.1175/JPO
Highly resolved pressure measurements on the seafloor over New Jersey’s continental shelf reveal the pressure signature of nonlinear internal waves of depression as negative pressure perturbations. The sign of the perturbation is determined by the dominance of the internal hydrostatic pressure (p⁰Wh) due to isopycnal displacement over the contributions of...
Full Text:
N D U M 1151
DOI: 10.1175/2010JPO4444.1
� 2010 American Meteorological Society
The authors present inferences of diapycnal diffusivity from a compilation of over 5200 microstructure
profiles. As microstructure observations are sparse, these are supplemented with indirect measurements of
mixing obtained from (i) Thorpe-scale overturns from moored profilers, a finescale parameterization applied to
(ii) shipboard observations of upper-ocean shear, (iii) strain as...
Understanding of hydroclimatic processes in Africa has been hindered by the lack of in situ precipitation measurements. Satellite-based observations, in particular, the TRMM Multisatellite Precipitation Analysis (TMPA) have been pivotal to filling this void. The recently released Integrated Multisatellite Retrievals for GPM (IMERG) project aims to continue the legacy of...
The origin of the Pacific Decadal Oscillation (PDO), the leading mode of sea surface temperature variability for the North Pacific, is a matter of considerable debate. One paradigm views the PDO as an independent mode centered in the North Pacific, while another regards it as a largely reddened response to...
Sampling intervals of precipitation geochemistry measurements are often coarser than those required by fine-scale hydrometeorological models. This study presents a statistical method to temporally downscale geochemical tracer signals in precipitation so that they can be used in high-resolution, tracer-enabled applications. In this method, we separated the deterministic component of the...
I examine the strong co-variability between the surface divergence and vorticity and how it varies with latitude in the Pacific Ocean using surface vector winds from reanalysis and satellite scatterometer observations. This analysis was motivated in part by a significant correlation between divergence and vorticity over the global oceans that...
Lateral stirring is a basic oceanographic phenomenon affecting the distribution of physical, chemical, and biological fields. Eddy stirring at scales on the order of 100 km (the mesoscale) is fairly well understood and explicitly represented in modern eddy-resolving numerical models of global ocean circulation. The same cannot be said for...
DYNAMO and TOGA-COARE observations and reanalysis-based surface flux products are
used to test theories of atmosphere-ocean interaction that explain the Madden-Julian
Oscillation (MJO). Negative intraseasonal outgoing longwave radiation, indicating deep
convective clouds, is in phase with increased surface wind stress, decreased solar heating,
and increased surface turbulent heat flux—mostly evaporation—from...
Full Text:
of
Climate, 28(2), 597-622. doi:10.1175/JCLI-D-14-00477.1
10.1175/JCLI-D-14-00477.1
American
Density currents (i.e., cold pools or outflows) beneath marine stratocumulus clouds are characterized using 30 days of ship-based observations obtained during the 2008 Variability of American Monsoon Systems (VAMOS) Ocean–Cloud–Atmosphere–Land Study Regional Experiment (VOCALS-REx) in the southeast Pacific. An air density increase criterion applied to the Improved Meteorological (IMET) sensor...
Emerging application areas such as air pollution in megacities, wind energy, urban security, and operation of unmanned aerial vehicles have intensified scientific and societal interest in mountain meteorology. To address scientific needs and help improve the prediction of mountain weather, the U.S. Department of Defense has funded a research effort—the...
Full Text:
mountain weather. Bulletin of the American Meteorological Society,
96(11), 1945–1967. doi:10.1175/BAMS-D
The diurnal variability and the environmental conditions that support the moisture resurgence of MJO events observed during the Cooperative Indian Ocean Experiment on Intraseasonal Variability (CINDY)/DYNAMO campaign in October–December 2011 are investigated using in situ observations and the cloud-resolving fully air–ocean–wave Coupled Ocean–Atmosphere Mesoscale Prediction System (COAMPS). Spectral density and...
The dominant processes governing ocean mixing during an active phase of the Madden–Julian oscillation are identified. Air–sea fluxes and upper-ocean currents and hydrography, measured aboard the R/V Revelle during boreal fall 2011 in the Indian Ocean at 0°, 80.5°E, are integrated by means of a large-eddy simulation (LES) to infer...
DYNAMO and TOGA-COARE observations and reanalysis-based surface flux products are
used to test theories of atmosphere-ocean interaction that explain the Madden-Julian
Oscillation (MJO). Negative intraseasonal outgoing longwave radiation, indicating deep
convective clouds, is in phase with increased surface wind stress, decreased solar heating,
and increased surface turbulent heat flux—mostly evaporation—from...
Full Text:
Interaction in TOGA COARE and DYNAMO. Journal of
Climate, 28(2), 597-622. doi:10.1175/JCLI-D-14-00477.1
Little is known about mixing in the abyssal equatorial oceans in spite of its inferred importance for upwelling dense water. Here we present full-depth microstructure turbulence profiles obtained in the equatorial Pacific that show evidence for intense wind-generated abyssal mixing. Mixing was intensified over the bottom 700 m where the...
Full Text:
circulation induced by a forced-dissipated Yanai
beam, J. Phys. Oceanogr., 40(5), 1118–1142, doi:10.1175
The semidiurnal mode-1 internal tide receives 0.1-0.3 TW from the surface tide and is capable of propagating across ocean basins. The ultimate fate of mode-1 energy after long-distance propagation is poorly constrained by existing observations and numerical simulations. Here, global results from a two-dimensional semi-analytical model indicate that topographic scattering...
Observations of winds, waves, and turbulence at the ocean surface are compared with several analytic formulations and a numerical model for the input of turbulent kinetic energy by wave breaking and the subsequent dissipation. The observations are generally consistent with all of the formulations, although some differences are notable at...
Intensified diurnal tides are found along portions of the Oregon shelf (U.S. West Coast) based on analyses
of high-frequency (HF) radar surface current data and outputs of a 1-km resolution ocean circulation model.
The K₁ tidal currents with magnitudes near 0.07 m s⁻¹ over a wider part of the shelf...
Simulations from a regional climate model (RCM) as part of a superensemble experiment were compared with observations of surface meteorological variables over the western United States. The RCM is the Hadley Centre Regional Climate Model, version 3, with improved physics parameterizations (HadRM3P) run at 25-km resolution and nested within the...
Full Text:
, 28(19),
7470-7488. doi:10.1175/JCLI-D-14-00808.1
10.1175/JCLI-D-14-00808.1
American Meteorological
Subtropical marine stratus clouds regulate coastal and global climate, but future trends in these
clouds are uncertain. In coastal Southern California (CSCA), interannual variations in summer stratus cloud
occurrence are spatially coherent across 24 airfields and dictated by positive relationships with stability
above the marine boundary layer (MBL) and MBL...
Full Text:
Oceans, J. Clim., 27(2), 925–940, doi:10.1175/JCLI-D-13-00165.1.
Bellomo, K., A. Clement, T. Mauritsen, G
The decline in Barents Sea ice has been implicated in forcing the “warm-Arctic cold-Siberian” (WACS) anomaly pattern via enhanced turbulent heat flux (THF). This study investigates interannual variability in winter [December–February (DJF)] Barents Sea THF and its relationship to Barents Sea ice and the large-scale atmospheric flow. ERA-Interim and observational...
The authors investigate atmospheric internal gravity waves (IGWs): their generation and induction of global intermittent turbulence in the nocturnal stable atmospheric boundary layer based on the new concept of turbulence generation discussed in a prior paper by Sun et al. The IGWs are generated by air lifted by convergence forced...
The wind speed response to mesoscale SST variability is investigated over the Agulhas Return Current region of the Southern Ocean using the Weather Research and Forecasting (WRF) Model and the U.S. Navy Coupled Ocean–Atmosphere Mesoscale Prediction System (COAMPS) atmospheric model. The SST-induced wind response is assessed from eight simulations with...
Kelvin-Helmholtz (KH) instability, characterized by the distinctive finite-amplitude billows it generates, is an important mechanism in the development of turbulence in the stratified interior of the ocean. In particular, it is often assumed that the onset of turbulence in internal waves begins in this way. Clear recognition of the importance...
Two methods of computing the time-mean divergence and vorticity from satellite vector winds in rain-free (RF) and all-weather (AW) conditions are investigated. Consequences of removing rain-contaminated winds on the mean divergence and vorticity depend strongly on the order in which the time-average and spatial derivative operations are applied. Taking derivatives...
Over 5000 aircraft eddy-covariance measurements from four different aircraft in nine different experiments are used to develop a simple model for the friction velocity over the sea. Unlike the widely used Coupled Ocean–Atmosphere Response Experiment (COARE) bulk flux scheme, the simple model (i) does not use Monin–Obukhov similarity theory (MOST)...
Sea surface temperature (SST) variability at intraseasonal time scales across the Indonesian Seas during January 1998–mid-2012 is examined. The intraseasonal variability is most energetic in the Banda and Timor Seas, with a standard deviation of 0.4°–0.5°C, representing 55%–60% of total nonseasonal SST variance. A slab ocean model demonstrates that intraseasonal...
Cloud-resolving large-eddy simulations (LES) on a 500 km × 500 km periodic domain coupled to a thermodynamic ocean mixed layer are used to study the effect of large-scale moisture convergence M on the convective population and heat and moisture budgets of the tropical atmosphere, for several simulations with M representative...
The Luzon Strait is the generation region for strong internal tides that radiate westward into the South China Sea and eastward into the western Pacific. Intrusions of the Kuroshio and strong mesoscale variability in the Luzon Strait can influence their generation and propagation. Here, the authors use eight moorings and...
Full Text:
Luzon Strait. Journal of
Physical Oceanography, 45(6), 1574-1594. doi:10.1175/JPO-D-14-0250.1
10.1175
Previous observations and simulations suggest that an approximate 3°–5°C warming occurred at intermediate depths in the North Atlantic over several millennia during Heinrich stadial 1 (HS1), which induces warm salty water (WSW) lying beneath surface cold freshwater. This arrangement eventually generates ocean convective available potential energy (OCAPE), the maximum potential...
The life cycles of three Madden–Julian oscillation (MJO) events were observed over the Indian Ocean as part of the Dynamics of the MJO (DYNAMO) experiment. During November 2011 near 0°, 80°E, the site of the research vessel Roger Revelle, the authors observed intense multiscale interactions within an MJO convective envelope,...
Intensive sampling of the deep Mediterranean outflow 70 km W of the Strait of Gibraltar reveals a strong, tidally modulated gravity current embedded with large-amplitude oscillations and energetic turbulence. The flow appears to be hydraulically controlled at a small topographic constriction, with turbulence and internal waves varying together and increasing...
This paper investigates the mechanisms of convective cloud organization by precipitation-driven cold pools over the warm tropical Indian Ocean during the 2011 Atmospheric Radiation Measurement (ARM) Madden-Julian Oscillation (MJO) Investigation Experiment/Dynamics of the MJO (AMIE/DYNAMO) field campaign. A high-resolution regional model simulation is performed using the Weather Research and Forecasting...
The Clouds, Aerosol, and Precipitation in the Marine Boundary Layer (CAP-MBL) deployment at Graciosa Island in the Azores generated a 21-month (April 2009–December 2010) comprehensive dataset documenting clouds, aerosols, and precipitation using the Atmospheric Radiation Measurement Program (ARM) Mobile Facility (AMF). The scientific aim of the deployment is to gain...
Internal waves are often observed to break close to the seafloor topography that generates them, or from which they scatter. This breaking is often spectacular, with turbulent structures observed hundreds of meters above the seafloor, and driving turbulence dissipations and mixing up to 10,000 times open-ocean levels. This article provides...
The loss of Arctic sea ice has emerged as a leading signal of global warming. This, together with acknowledged impacts on other components of the Earth system, has led to the term “the new Arctic.” Global coupled climate models predict that ice loss will continue through the twenty-first century, with...
Internal waves of depression were observed propagating
along‐shelf and into northern Monterey Bay, California
(CA) on the inner shelf. These waves had amplitudes
approximately equal to the thermocline depth (∼4 m), and
were unstable to shear and mix the thermocline. Isopycnal
gradient spectra showed that the wave packets lead to...
Mineral dust particles have been shown to act as cloud condensation nuclei, and they are known to interact
with developing tropical storms over the Atlantic downwind of the Sahara. Once present within liquid
droplets, they have the potential to act as freezing ice nuclei and further affect the microphysics, dynamics,...
In this thesis, high resolution ocean models are used to evaluate and forecast coastal ocean variability in two different applications. In the first study, the 2-km resolution ocean circulation model for the Eastern Bering Sea is utilized to understand whether slope-interior exchange along the path of the Aleutian North Slope...
The impacts of North Atlantic Oscillation (NAO) and El Niño–Southern Oscillation (ENSO) on Great Lakes ice cover were investigated using lake ice observations for winters 1963–2010 and National Centers for Environmental Prediction reanalysis data. It is found that both NAO and ENSO have impacts on Great Lakes ice cover. The...
Lateral stirring is a basic oceanographic phenomenon affecting the distribution of physical, chemical, and biological fields. Eddy stirring at scales on the order of 100 km (the mesoscale) is fairly well understood and explicitly represented in modern eddy-resolving numerical models of global ocean circulation. The same cannot be said for...
Pressure differences across topography generate a form drag that opposes the flow in the water column, and viscous and pressure forces acting on roughness elements of the topographic surface generate a frictional drag on the bottom. Form drag and bottom roughness lengths were estimated over the East Flower Garden Bank...
Formation of cirrus clouds depends on the availability of ice nuclei to begin condensation of atmospheric water vapor. Although it is known that only a small fraction of atmospheric aerosols are efficient ice nuclei, the critical ingredients that make those aerosols so effective have not been established. We have determined...
Full Text:
. Atmos. Ocean. Technol. 20, 781 (2003).
doi:10.1175/1520-0426(2003)020<0781:POACVI>2.0.CO;2
35. C. S
A synthesis of over 2000 paleoclimate proxy records is performed via a data assimilation framework that expands upon previous efforts by implementing a suite of physically-based proxy system models, and which provides the first example of an observationally independent, multi-seasonal (DJFM, JJAS) paleoclimate reanalysis. This methodology is contrasted against previous...
In this study, uncoupled and coupled ocean–atmosphere simulations are carried out for the California Upwelling System to assess the dynamic ocean–atmosphere interactions, namely, the ocean surface current feedback to the atmosphere. The authors show the current feedback, by modulating the energy transfer from the atmosphere to the ocean, controls the...
During fall/winter off the Oregon coast, oceanographic surveys are relatively scarce because of rough
weather conditions. This challenge has been overcome by the use of autonomous underwater gliders deployed
along the Newport hydrographic line (NH-Line) nearly continuously since 2006. The discharge from the
coastal rivers between northern California and the...
Shore-based video remote sensing is used to observe and continually monitor nonlinear internal waves
propagating across the inner shelf. Month-long measurements of velocity from bottom-mounted acoustic
Doppler current profilers and temperature from thermistor chains at the 10- and 20-m isobaths are combined
with sea surface imagery from a suite of...
Full Text:
, 31(3), 714-728.
doi:10.1175/JTECH-D-13-00098.1
10.1175/JTECH-D-13-00098.1
American Meteorological
High-resolution ship-based observations of a nearly uniform stratocumulus deck in the southeast Pacific during 17 days of the 2008 VOCALS regional experiment elucidate radiation and turbulence in the marine boundary layer (MBL). A new method for prescribing observations-based cloud properties to the Rapid Radiative Transfer Model is presented and applied...
Moored observations are used to investigate the seasonal change in vertical structure of the cross-shelf
circulation at a midshelf location in the northern California Current System. A streamwise–normal coordinate
system is employed to eliminate meander- and eddy-induced biases in the cross-shelf flow that are unaccounted
for with an alternative, commonly...
Strong modulation of turbulent mixing by a westward-propagating tropical instability wave (TIW) was observed in the stratified shear layer between the equatorial undercurrent (EUC) and the surface mixed layer during October and November 2008 at 0°N 140°W. The unique deep diurnal-cycle mixing in the stratified layer beneath the equatorial cold...
The Oregon Coastal Transition Zone (OCTZ) extends several hundred
kilometers offshore where shelf flows interact with the northern California Current. A
primitive-equation numerical ocean model is used to study the upwelling circulation in this
region from 1 May to 1 November 2001. This OCTZ model obtains initial and boundary
conditions...
The spatial variability of turbulence and surface heat flux are examined for the case of small air-surface temperature difference and modest sea-surface temperature variability. As a result of nonlinearities in the bulk formula, the heterogeneity is predicted to shift the area-averaged heat flux toward more significant upward values compared to...
Interannual variation in precipitation totals is a critical factor governing the year-to-year availability of water resources, yet the connection between interannual precipitation variability and underlying event- and season-scale precipitation variability remains unclear. In this study, tropical and midlatitude precipitation characteristics derived from extensive station records and high-frequency satellite observations were...
We present observations from deployments of a microstructure turbulence instrument
(the Towed Microstructure and Auxiliary Sensor Instrument) aboard a pumping profiling
vehicle (the Lamont Pumping SeaSoar) towed behind a research vessel at the New
England shelf break front in August 2002. From these we determined coincident fine-scale
vertical eddy diffusivity...
Basin-scale superinertial oceanic tides have been observed globally to resonate with the continental shelf (e.g., the Patagonian Shelf) with a clear theoretical framework. However, the response of the shelf to atmospheric tides – another basin-scale forcing – has not been discussed. This study explores this response using a prominent S2...
In situ observations of tidally driven turbulence were obtained in a small channel that transects the crest of the Mendocino Ridge, a site of mixed (diurnal and semidiurnal) tides. Diurnal tides are subinertial at this latitude, and once per day a trapped tide leads to large flows through the channel...
The goal of the Pacific Ocean Boundary Ecosystem and Climate Study
(POBEX) was to diagnose the large-scale climate controls on regional transport
dynamics and lower trophic marine ecosystem variability in Pacific Ocean boundary
systems. An international team of collaborators shared observational and eddy-resolving
modeling data sets collected in the Northeast...
Vertical transports of plankton, momentum, heat, and turbulence are modeled. A novel integration of high resolution turbulence and biophysical modeling is used to show the influence of a Kelvin-Helmholtz instability on the vertical migration of simple gyrotactic organisms. A viscous limit on mixing driven by shear turbulence is proposed. Large...
Soil moisture is an essential climate variable influencing land–atmosphere interactions, an essential hydrologic variable impacting rainfall–runoff processes, an essential ecological variable regulating net ecosystem exchange, and an essential agricultural variable constraining food security. Large-scale soil moisture monitoring has advanced in recent years, creating opportunities to transform scientific understanding of soil...
Though numerous drought metrics have been developed by the research community, adoption of these metrics by water managers has been limited. The reasons for this vary, but some include mismatches in time scales and spatial scales between the metric supplied and the operational decisions (e.g. water managers often work within...
Summertime low clouds are common in the Pacific Northwest (PNW), but spatiotemporal patterns have not been characterized. We show the first maps of low cloudiness for the western PNW and North Pacific Ocean using a 22‐year satellite‐derived record of monthly mean low cloudiness frequency for May through September and supplemented...
We apply GENMOM, a coupled atmosphere–ocean climate model, to simulate eight equilibrium time
slices at 3000-year intervals for the past 21,000 years forced
by changes in Earth–Sun geometry, atmospheric greenhouse
gases (GHGs), continental ice sheets, and sea level. Simulated
global cooling during the Last Glacial Maximum
(LGM) is 3.8°C and...
Full Text:
Climate, 24(19), 4973–4991, doi:10.1175/2011JCLI4083.1, 2011.
Harrison, S. P., Bartlein, P. J., Brewer
Semidiurnal velocity and density oscillations are examined over the mid- and inner continental shelf near Heceta Bank on the Oregon coast. Measurements from two long-term observation networks with sites on and off the submarine bank reveal that both baroclinic velocities and displacements are dominated by the first mode, with larger...
Three mechanisms for self-induced Ekman pumping in the interiors of mesoscale ocean eddies are investigated.
The first arises from the surface stress that occurs because of differences between surface wind and
ocean velocities, resulting in Ekman upwelling and downwelling in the cores of anticyclones and cyclones,
respectively. The second mechanism...
Across-shelf transects over the eastern flank of Barrow Canyon were obtained in August 2005 with an autonomous underwater vehicle (AUV). Here, the shelf topography creates a “choke” point in which a substantial portion of Pacific inflow from the Bering Strait is concentrated within 30 km of the coast, providing an...
Collocated Moderate Resolution Imaging Spectroradiometer (MODIS) imagery and
Cloud‐Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) 532 nm
total attenuated backscatter coefficients were used to identify 50 km scale segments
for ocean regions that had only a single layer of marine stratocumulus. On the basis of
whether the underlying ocean...
Linkages between land use and its influence on the atmosphere have been a long-standing research area. For example, what is the impact of irrigated agriculture on downwind rainfall? Global-scale models show that moisture recycling is an important source of water for inland regions around the world, but they do not...
In order to better understand the general problem of satellite cloud top height
retrievals for low clouds, observations made by NOAA research vessels in the
stratocumulus region in the southeastern Pacific during cruises in 2001 and 2003 to 2006
were matched with near-coincident retrievals from the Moderate Resolution Imaging
Spectroradiometer...
The glaciated coastal mountain watersheds that drain into the Gulf of Alaska (GOA) provide a model laboratory to explore the challenges of hydrological modeling and study the impact of climate and glacier cover change on regional hydrology. The region is data-sparse and contains a complex assemblage of topography and land...
Turbulent bottom Ekman layers are among the most important energy conversion sites in the ocean. Their energetics are notoriously complex, in particular near sloping topography, where the feedback between cross-slope Ekman transports, buoyancy forcing, and mixing affects the energy budget in ways that are not well understood. Here, the authors...
Oceanic density overturns are commonly used to parameterize the dissipation rate of turbulent kinetic energy. This method assumes a linear scaling between the Thorpe length scale L[subscript]T and the Ozmidov length scale L[subscript]O. Historic evidence supporting L[subscript]T ~ L[subscript]O has been shown for relatively weak shear-driven turbulence of the thermocline;...
Assessing uncertainties in hydrologic models can improve accuracy in predicting future streamflow. Here,
simulated streamflows using the Variable Infiltration Capacity (VIC) model at coarse (1/16°) and fine (1/120°)
spatial resolutions were evaluated against observed streamflows from 217 watersheds. In particular, the adequacy
of VIC simulations in groundwater- versus runoff-dominated watersheds...
Surface tides are the heartbeat of the ocean. Because they are controlled by Earth's motion relative to other astronomical objects in our solar system, surface tides act like clockwork and generate highly deterministic ebb and flow familiar to all mariners. In contrast, baroclinic motions at tidal frequencies are much more...
Measurements that link surface conditions and climate can provide critical information on important biospheric changes occurring in the Earth system. As the direct driving force of energy and water fluxes at the surface-atmosphere interface, land surface temperature (LST) provides information on physical processes of land-cover change and energy-balance changes that...
The daytime evolution of warm cloud microphysical properties over the southeast Pacific during October–November 2008 is investigated with optical/infrared retrievals from the Tenth Geostationary Operational Environmental Satellite (GOES-10) imager. GOES-10 retrievals, produced at NASA Langley Research Center, are validated against in situ aircraft observations and with independent satellite observations. Comparisons...
Little is known about mixing in the abyssal equatorial oceans in spite of its inferred importance for upwelling dense water. Here we present full-depth microstructure turbulence profiles obtained in the equatorial Pacific that show evidence for intense wind-generated abyssal mixing. Mixing was intensified over the bottom 700 m where the...
Full Text:
, J. Phys. Oceanogr., 32 (7), 2113–2130, doi:10.1175/1520-
0485(2002)032<2113:OOBMOT>2.0.CO;2.
Moum
A comprehensive study of the Gulf of Alaska (GOA) drainage basin was carried out to improve understanding of the coastal freshwater discharge (FWD) and glacier volume loss (GVL). Hydrologic processes during the period 1980–2014 were modeled using a suite of physically based, spatially distributed weather, energy-balance snow/ice melt, soil water...
The impact of anthropogenic forcing on the probability of high mean summer temperatures being exceeded in Texas in the year 2011 was investigated using an atmospheric circulation model to simulate large ensembles of the world with 2011 level forcing and 5 counterfactual worlds under preindustrial forcing. In Texas, drought is...
Full Text:
, 2811–2832, doi:10.1175/JCLI-D-12-00270.1.
Imada, Y., H. Shiogama, M. Watanabe, M. Mori, M. Ishii, and M
In this modeling study we investigate the dynamical mechanisms controlling the spreading of the Magellan Plume, which is a low-salinity tongue that extends along the Patagonian Shelf. Our results indicate that the overall characteristics of the plume (width, depth, spreading rate, etc.) are primarily influenced by tidal forcing, which manifests...
Currently, forecasts produced by the Oregon-Washington (OR-WA) Coastal Ocean Forecast System are constrained by assimilation of only surface observations. The 4-dimensional variational (4DVAR) data assimilation (DA) algorithm is utilized to combine the model and the data, with the time-independent forecast ("background'') error covariance B. In this study, two possible improvements...
Global warming is expected to cause significant changes in the pattern of precipitation minus evaporation (𝑃 − 𝐸), which represents the net flux of water from the atmosphere to the surface or, equivalently, the convergence of moisture transport within the atmosphere. In most global climate model simulations, the pattern of...
We apply GENMOM, a coupled atmosphere–ocean climate model, to simulate eight equilibrium time
slices at 3000-year intervals for the past 21,000 years forced
by changes in Earth–Sun geometry, atmospheric greenhouse
gases (GHGs), continental ice sheets, and sea level. Simulated
global cooling during the Last Glacial Maximum
(LGM) is 3.8°C and...
The evolution of the near-inertial internal wavefield from ice-free summertime conditions to ice-covered wintertime conditions is examined using data from a yearlong deployment of six moorings on the Beaufort continental slope from August 2008 to August 2009. When ice is absent, from July to October, energy is efficiently transferred from...
In the mountains of the Western US, shifts in the timing and magnitude of snow water equivalent (SWE) over the past century are well documented and attributed to climate warming, but the magnitude of sensitivity depends on elevation. We modeled the spatial distribution of SWE and its sensitivity to climate...
The coastal region is home to many types of surface fronts that exist on a submesoscale (1-10 $km$). While in situ observations capture point or transect observations of frontal behavior subsurface, their complex spatial patterns can be well-captured using remote sensing techniques, which provide synoptic views of the ocean surface...
The role of evapotranspiration (ET) in the global, continental, regional, and local water cycles is reviewed. Elevated atmospheric CO₂, air temperature, vapor pressure deficit (D), turbulent transport, radiative transfer, and reduced soil moisture all impact biotic and abiotic processes controlling ET that must be extrapolated to large scales. Suggesting a...
The topics in this dissertation center on the snow processes that dominate mountain environments in the Western U.S. and Alaska, particularly in locations lacking long-term observational datasets or locales that are difficult to access in-person. Some are currently glacierized or have been glaciated in the recent past. Each of the...
A low-power (<10 mW), physically small (15.6 cm long × 3.2 cm diameter), lightweight (600 g Cu; alternatively, 200 g Al), robust, and simply calibrated pitot-static tube to measure mean speed and turbulence dissipation (ε ) is described and evaluated. The measurement of speed is derived from differential pressure via...
Many investigations using satellite data have determined that aerosol optical depth and cloud cover are correlated and some have interpreted the correlation as evidence of an aerosol indirect effect on clouds. This study uses in situ aircraft observations taken during the Indian Ocean Experiment (INDOEX), February–March 1999, and mostly over...
This work advances a unified approach to process-based hydrologic modeling to enable controlled and systematic evaluation of multiple model representations (hypotheses) of hydrologic processes and scaling behavior. Our approach, which we term the Structure for Unifying Multiple Modeling Alternatives (SUMMA), formulates a general set of conservation equations, providing the flexibility...
The tidally varying circulation, stratification, and salt flux mechanisms are
investigated in a shallow salt wedge estuary where fluvial and tidal velocities are large and
the steady baroclinic circulation is comparatively weak. The study integrates field
observations and numerical simulations of the Merrimack River estuary. At moderate to
high discharge...
For this project, we designed a soot modeling software to produce a full particle density function. This model uses the Direct Simulation Monte Carlo with a full conditioning particle selection method to capture soot nucleation and coagulation in a diffusion flame. We investigate the use of graphic processing units as...
In determining aerosol-cloud interactions, the properties of aerosols must be characterized in the vicinity of clouds. Numerous studies based on satellite observations have reported that aerosol optical depths increase with increasing cloud cover. Part of the increase comes from the humidification and consequent growth of aerosol particles in the moist...
The connectivity among straits of the northwest Pacific marginal seas is investigated with a primitive-equation ocean circulation model simulated for 10 years from 1994 to 2003. Over the simulation interval the temporal and spatial means and variations of the model sea surface temperature are comparable to those of the satellite...
An intermediate-complexity climate model is used to simulate the impact of an accelerated Pine Island Glacier mass loss on the large-scale ocean circulation and climate. Simulations are performed for preindustrial conditions using hosing levels consistent with present-day observations of 3000 m³ s⁻¹, at an accelerated rate of 6000 m³ s⁻¹,...