Occurrence of shallow cold flows in the winter atmospheric boundary layer of interior of Alaska

Fochesatto, G. J.; Mayfield, John A.; Starkenburg, D. P.; Gruber, Matthew A.; Conner, James F.

doi:10.1007/s00703-013-0274-4

Cited by 17 publications

(16 citation statements)

References 43 publications

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“…Those authors further proposed that topography surrounding Fairbanks supports gravity wind drainage to the south. Drainage flows into the basin surrounding Fairbanks are closely linked to local cold spells (Fochesatto et al, 2013).…”

Section: Extreme Cold Temperaturesmentioning

confidence: 99%

Evaluation of synoptic‐scale patterns during extreme temperature and precipitation events in Alaska

DeLaFrance

McAfee

2019

Intl Journal of Climatology

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Synoptic‐scale patterns associated with daily temperature and precipitation extremes in Alaska are identified and evaluated for daily variability in order to understand consistency in forcing mechanisms associated with extreme events as well as the tendency for each pattern to produce an extreme event. Daily station data at five locations for the 29‐year period from 1982 to 2010 are used. The widely recognized ClimDex indices are used to identify extreme high temperature, low temperature, and single‐day precipitation events. Pressure patterns during extreme events are evaluated seasonally for summer (JJA) and winter (DJF) at mean sea level pressure, 700 and 500‐hPa geopotential heights. Temperature extremes are largely characterized by synoptic‐scale patterns associated with substantial warm and cold air advection, and precipitation extremes are associated with moisture advection from the North Pacific. Extreme warm and cold temperature events are generally associated with more consistent daily synoptic‐scale patterns than precipitation. Considerable dissimilarities among daily synoptic‐scale patterns associated with extreme events based on location, type of extreme event and season highlight the need for careful consideration in the practice of applying synoptic‐scale forcing patterns to forecast or downscale extreme weather events in Alaska.

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Section: Extreme Cold Temperaturesmentioning

confidence: 99%

Evaluation of synoptic‐scale patterns during extreme temperature and precipitation events in Alaska

DeLaFrance

McAfee

2019

Intl Journal of Climatology

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“…Sensible heat flux was measured locally (i.e., ecosystem scale) by means of and eddy-covariance (EC) instrument and processed considering signal distortions under all weather conditions [27] and, at landscape scale, based on a large aperture scintillometer (LAS) [28][29][30].…”

Section: Field Experimentsmentioning

confidence: 99%

Evapotranspiration in Northern Agro-Ecosystems: Numerical Simulation and Experimental Comparison

Ruairuen¹,

Fochesatto²,

Bittelli³

et al. 2017

Current Perspective to Predict Actual Evapotranspiration

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Evapotranspiration and near-surface soil moisture dynamics are key-entangled variables regulating flux at the surface-atmosphere interface. Both are central in improving mass and energy balances in agro ecosystems. However, under the extreme conditions of high-latitude soils and weather pattern variability, the implementation of such coupled liquid and vapor phase numerical simulation remain to be tested. We consider the nonisothermal solution of the vapor flux equation that accounts for the thermally driven water vapor transport and phase changes. Fully coupled flux model outputs are compared and contrasted against field measurements of soil temperature, heat flux, water content, and evaporation in a subarctic agroecosystem in Alaska. Two welldefined hydro-meteorological situations were selected: dry and wet periods. Numerical simulation was forced by time series of incoming global solar radiation and atmospheric surface layer thermodynamic parameters: surface wind speed, ambient temperature, relative humidity, precipitation, and soil temperature and soil moisture. In this simulation, soil parameters changing in depth and time are considered as dynamically adjusted boundary conditions for solving the set of coupled differential equations. Results from this evaluation give good correlation of modeled and observed data in ) during the dry period. On the other hand, a poor agreement was obtained in the radiative fluxes and turbulent fluxes during the wet period due to the lack of representation in the radiation field and differences in soil dynamics across the landscape.

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“…In addition to sonic anemometers, SC is also equipped with four cup anemometers, and both domains employ air temperature and humidity sensors at multiple heights. During the IOP, a Doppler acoustic sounder (sodar) was deployed to characterize the mesoscale flow common to both domains [ Mayfield and Fochesatto , ; Fochesatto et al ., ; Malingowski et al ., ].…”

Section: Selection Of Cases Site Characteristics and Instrumentationmentioning

confidence: 99%

Temperature regimes and turbulent heat fluxes across a heterogeneous canopy in an Alaskan boreal forest

et al. 2015

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We evaluate local differences in thermal regimes and turbulent heat fluxes across the heterogeneous canopy of a black spruce boreal forest on discontinuous permafrost in interior Alaska. The data were taken during an intensive observing period in the summer of 2013 from two micrometeorological towers 600 m apart in a central section of boreal forest, one in a denser canopy (DC) and the other in a sparser canopy, but under approximately similar atmospheric boundary layer (ABL) flow conditions. Results suggest that on average 34% of the half-hourly periods in a day are nonstationary, primarily during night and during ABL transitions. Also, thermal regimes differ between the two towers; specifically between midnight and 0500 Alaska Standard Time (AKST) it is about 3°C warmer at DC. On average, the sensible heat flux at DC was greater. For midday periods, the difference between those fluxes exceeded 30% of the measured flux and over 30 W m À2 in magnitude more than 60% of the time. These differences are due to higher mechanical mixing as a result of the increased density of roughness elements at DC. Finally, the vertical distribution of turbulent heat fluxes verifies a maximum atop the canopy crown (2.6 h) when compared with the subcanopy (0.6 h) and above canopy (5.1 h), where h is the mean canopy height. We argue that these spatial and vertical variations of sensible heat fluxes result from the complex scale aggregation of energy fluxes over a heterogeneous canopy.

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Occurrence of shallow cold flows in the winter atmospheric boundary layer of interior of Alaska

Cited by 17 publications

References 43 publications

Evaluation of synoptic‐scale patterns during extreme temperature and precipitation events in Alaska

Evaluation of synoptic‐scale patterns during extreme temperature and precipitation events in Alaska

Evapotranspiration in Northern Agro-Ecosystems: Numerical Simulation and Experimental Comparison

Temperature regimes and turbulent heat fluxes across a heterogeneous canopy in an Alaskan boreal forest

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