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• 1. [Article] The fluxes of latent and sensible heat in the marine boundary layer

  Measurements of the fluctuations of humidity, temperature and velocity were made in the marine boundary layer. The humidity fluctuations were measured with a Lyman-alpha humidiometer. Temperature fluctuations ...

  Citation × Citation Citation Abstract Copy Title: The fluxes of latent and sensible heat in the marine boundary layer Author: Phelps, George Thomas Measurements of the fluctuations of humidity, temperature and velocity were made in the marine boundary layer. The humidity fluctuations were measured with a Lyman-alpha humidiometer. Temperature fluctuations were measured with a dry thermocouple and a platinum resistance thermometer. Velocity fluctuations were measured with a three component sonic anemometer. These measurements were made from the Floating Instrument Platform (FLIP) operated by the Scripps Institution of Oceanography near San Diego in February, 1969 and during the Barbados Oceanographic and Meteorological Expedition (BOMEX) in May 1969. The data were processed by digital techniques and the various spectra, cospectra and quadspectra between the velocities, humidity and temperature were obtained. Integrals of the cospectra were produced which allowed estimates of the fluxes of latent and sensible heat to be made. The normalized spectra of humidity fluctuations in San Diego and BOMEX have similar shapes. The normalized cospectra between vertical velocity and humidity in San Diego and BOMEX have similar shapes. Universal forms for the normalized humidity spectrum and the normalized cospectrum between vertical velocity and humidity may exist. The normalized spectra of the temperature fluctuations in San Diego and BOMEX have different shapes. The differences in shapes may be related to stronger radiation effects during BOMEX than in San Diego. The normalized cospectra between vertical velocity and temperature in San Diego and BOMEX also have different shapes. It is probable that a universal form does not exist for the normalized temperature spectrum or for the normalized cospectrum between vertical velocity and temperature. Directly measured values of the latent and sensible heat fluxes were used to test the validity of the bulk aerodynamic method of predicting the latent and sensible heat fluxes from the mean wind speed and mean air-sea humidity or temperature differences. The limited results from San Diego indicate that the sensible heat flux may probably be predicted from the mean wind speed and the mean air-sea temperature difference in temperate regions. The bulk aerodynamic method was not useful for predicting the sensible heat flux in BOMEX. The observed values for the sensible heat flux were much larger than would be predicted. The latent heat flux could be predicted from the mean wind speed and the mean air-sea absolute humidity difference with a probable error of less than 20%. The validity of the formula developed by Bowen (1926) for predicting the Bowen ratio (sensible heat flux/latent heat flux) was tested with directly measured values of the Bowen ratio. It was found that in San Diego the Bowen ratio could be predicted with a probable error of 15%. The Bowen ratio predicted for BOMEX was too low by a factor of two or more. The ability to predict the Bowen ratio from the ratio of the temperature fluctuations to the humidity fluctuations in the 0.05-0.1 Hz range was investigated. The method predicted the Bowen ratio with a probable error of 15% in San Diego and 20% in BOMEX. Title: The fluxes of latent and sensible heat in the marine boundary layer Author: Phelps, George Thomas Measurements of the fluctuations of humidity, temperature and velocity were made in the marine boundary layer. The humidity fluctuations were measured with a Lyman-alpha humidiometer. Temperature fluctuations were measured with a dry thermocouple and a platinum resistance thermometer. Velocity fluctuations were measured with a three component sonic anemometer. These measurements were made from the Floating Instrument Platform (FLIP) operated by the Scripps Institution of Oceanography near San Diego in February, 1969 and during the Barbados Oceanographic and Meteorological Expedition (BOMEX) in May 1969. The data were processed by digital techniques and the various spectra, cospectra and quadspectra between the velocities, humidity and temperature were obtained. Integrals of the cospectra were produced which allowed estimates of the fluxes of latent and sensible heat to be made. The normalized spectra of humidity fluctuations in San Diego and BOMEX have similar shapes. The normalized cospectra between vertical velocity and humidity in San Diego and BOMEX have similar shapes. Universal forms for the normalized humidity spectrum and the normalized cospectrum between vertical velocity and humidity may exist. The normalized spectra of the temperature fluctuations in San Diego and BOMEX have different shapes. The differences in shapes may be related to stronger radiation effects during BOMEX than in San Diego. The normalized cospectra between vertical velocity and temperature in San Diego and BOMEX also have different shapes. It is probable that a universal form does not exist for the normalized temperature spectrum or for the normalized cospectrum between vertical velocity and temperature. Directly measured values of the latent and sensible heat fluxes were used to test the validity of the bulk aerodynamic method of predicting the latent and sensible heat fluxes from the mean wind speed and mean air-sea humidity or temperature differences. The limited results from San Diego indicate that the sensible heat flux may probably be predicted from the mean wind speed and the mean air-sea temperature difference in temperate regions. The bulk aerodynamic method was not useful for predicting the sensible heat flux in BOMEX. The observed values for the sensible heat flux were much larger than would be predicted. The latent heat flux could be predicted from the mean wind speed and the mean air-sea absolute humidity difference with a probable error of less than 20%. The validity of the formula developed by Bowen (1926) for predicting the Bowen ratio (sensible heat flux/latent heat flux) was tested with directly measured values of the Bowen ratio. It was found that in San Diego the Bowen ratio could be predicted with a probable error of 15%. The Bowen ratio predicted for BOMEX was too low by a factor of two or more. The ability to predict the Bowen ratio from the ratio of the temperature fluctuations to the humidity fluctuations in the 0.05-0.1 Hz range was investigated. The method predicted the Bowen ratio with a probable error of 15% in San Diego and 20% in BOMEX. Close

• 2. [Article] A statistical study of winds and sea water temperatures during Oregon coastal upwelling

  Citation × Citation Citation Abstract Copy Title: A statistical study of winds and sea water temperatures during Oregon coastal upwelling Author: Fisher, Carl W. Title: A statistical study of winds and sea water temperatures during Oregon coastal upwelling Author: Fisher, Carl W. Close

• 3. [Article] A comparison of eddy correlation and dissipation techniques for computing the fluxes of momentum, heat and moisture in the marine boundary layer

  The results of measurements of the fluxes of momentum, moisture and sensible heat in the marine boundary layer are described. Two techniques for obtaining the fluxes are discussed. The fluxes of these ...

  Citation × Citation Citation Abstract Copy Title: A comparison of eddy correlation and dissipation techniques for computing the fluxes of momentum, heat and moisture in the marine boundary layer Author: Paquin, James Edward The results of measurements of the fluxes of momentum, moisture and sensible heat in the marine boundary layer are described. Two techniques for obtaining the fluxes are discussed. The fluxes of these quantities are most directly obtained by the eddy correlation method, that is, by measuring the fluctuating vertical and downstream velocity (w and u), temperature (T) and humidity (q) and computing the covariances wu, wT and wq. The fluxes are also computed by obtaining a measure of the energy dissipation rate from second-order structure functions and relating the dissipation to the production of energy. To use the dissipation methods, values of universal inertial-convective subrange constants (Kolmogoroff constants) are required. Kolmogoroff constants are computed from second and third-order structure functions. Most of the data were collected on R.V. FLIP during BOMEX (Barbados Oceanographic and Meteorological Experiment) and during a pre-BOMEX trial cruise near San Diego. A small amount of additional data was collected from a site at South Beach, Oregon. The value of the Kolmogoroff constant for velocity is consistent with other recent observations. The temperature and humidity constants are found to be equal within the measurement error and have values of about 0.8. The two methods for computing the fluxes agree on average for momentum and moisture flux. The two methods do not agree for sensible heat flux during BOMEX although there is fair agreement for the San Diego data. Title: A comparison of eddy correlation and dissipation techniques for computing the fluxes of momentum, heat and moisture in the marine boundary layer Author: Paquin, James Edward The results of measurements of the fluxes of momentum, moisture and sensible heat in the marine boundary layer are described. Two techniques for obtaining the fluxes are discussed. The fluxes of these quantities are most directly obtained by the eddy correlation method, that is, by measuring the fluctuating vertical and downstream velocity (w and u), temperature (T) and humidity (q) and computing the covariances wu, wT and wq. The fluxes are also computed by obtaining a measure of the energy dissipation rate from second-order structure functions and relating the dissipation to the production of energy. To use the dissipation methods, values of universal inertial-convective subrange constants (Kolmogoroff constants) are required. Kolmogoroff constants are computed from second and third-order structure functions. Most of the data were collected on R.V. FLIP during BOMEX (Barbados Oceanographic and Meteorological Experiment) and during a pre-BOMEX trial cruise near San Diego. A small amount of additional data was collected from a site at South Beach, Oregon. The value of the Kolmogoroff constant for velocity is consistent with other recent observations. The temperature and humidity constants are found to be equal within the measurement error and have values of about 0.8. The two methods for computing the fluxes agree on average for momentum and moisture flux. The two methods do not agree for sensible heat flux during BOMEX although there is fair agreement for the San Diego data. Close

• 4. [Article] Towed thermistor chain observations in JASIN

  Citation × Citation Citation Abstract Copy Title: Towed thermistor chain observations in JASIN Author: Paulson, Clayton A., Baumann, R. J., Wagner, J., Oregon State University. School of Oceanography Title: Towed thermistor chain observations in JASIN Author: Paulson, Clayton A., Baumann, R. J., Wagner, J., Oregon State University. School of Oceanography Close

• 5. [Article] FRONTS 80 : preliminary results from an investigation of the wintertime North Pacific subtropical front

  Citation × Citation Citation Abstract Copy Title: FRONTS 80 : preliminary results from an investigation of the wintertime North Pacific subtropical front Author: Paulson, Clayton A., Niiler, Pearn P., Oregon State University. School of Oceanography Title: FRONTS 80 : preliminary results from an investigation of the wintertime North Pacific subtropical front Author: Paulson, Clayton A., Niiler, Pearn P., Oregon State University. School of Oceanography Close

• 6. [Article] Thermistor chain observations during MILDEX

  Citation × Citation Citation Abstract Copy Title: Thermistor chain observations during MILDEX Author: Levine, Murray D., Oregon State University. College of Oceanography, Simpkins, Jay, Gard, Steve R. Title: Thermistor chain observations during MILDEX Author: Levine, Murray D., Oregon State University. College of Oceanography, Simpkins, Jay, Gard, Steve R. Close

• 7. [Article] Relationship between tropical Atlantic Sea surface temperature variability and southern Indian Ocean tropical cyclones

  Recent studies have found that equatorial Atlantic sea surface temperature (SST) variability may be influencing tropical Indian Ocean climate (Kucharski 2009, Wang 2009). Due to the economic and social ...

  Citation × Citation Citation Abstract Copy Title: Relationship between tropical Atlantic Sea surface temperature variability and southern Indian Ocean tropical cyclones Author: DeBlander, Evan F. Recent studies have found that equatorial Atlantic sea surface temperature (SST) variability may be influencing tropical Indian Ocean climate (Kucharski 2009, Wang 2009). Due to the economic and social impact of tropical cyclones, it is important to investigate how an Atlantic-Indian Ocean connection may be affecting tropical cyclone behavior in the southern Indian Ocean. In this study, the International Best Track Archive for Climate Stewardship (IBTrAC) tropical cyclone database is used to derive metrics of tropical cyclone behavior, which are then compared with indices of tropical Atlantic SST variability representing Atlantic Niño, and Benguela Niño events. Changes in tropical Atlantic SSTs are found to coincide with significant differences in tropical cyclone activity for portions of the southern Indian Ocean. In addition, for these same regions, tropical Atlantic SST variability is associated with changes in large-scale atmospheric conditions, including steering flow, low level vorticity, and humidity, typically associated with tropical cyclogenesis, and tropical cyclone track. The changes in steering flow related to both indices of Atlantic SST anomaly are reproduced by an atmospheric model. The changes in steering flow are also found to be linked to changes in TC translational velocity, and TC tracking. These findings indicate a possible link between tropical Atlantic conditions and cyclone activity in the Indian Ocean mediated through a teleconnection between tropical Atlantic SSTs and large scale atmospheric conditions over the southern Indian Ocean. The teleconnection related to the Benguela Niño region of SST variability was found to consist of a Rossby wave initiated off the coast of South America, and propagating into the Indian Ocean, thereby influencing several atmospheric variables, including steering flow. The teleconnection related to the Atlantic Niño region of SST variability was not well defined, although there was some evidence of a Walker circulation anomaly extending from the equatorial Atlantic over the continent of Africa, and influencing SIO steering flow. Title: Relationship between tropical Atlantic Sea surface temperature variability and southern Indian Ocean tropical cyclones Author: DeBlander, Evan F. Recent studies have found that equatorial Atlantic sea surface temperature (SST) variability may be influencing tropical Indian Ocean climate (Kucharski 2009, Wang 2009). Due to the economic and social impact of tropical cyclones, it is important to investigate how an Atlantic-Indian Ocean connection may be affecting tropical cyclone behavior in the southern Indian Ocean. In this study, the International Best Track Archive for Climate Stewardship (IBTrAC) tropical cyclone database is used to derive metrics of tropical cyclone behavior, which are then compared with indices of tropical Atlantic SST variability representing Atlantic Niño, and Benguela Niño events. Changes in tropical Atlantic SSTs are found to coincide with significant differences in tropical cyclone activity for portions of the southern Indian Ocean. In addition, for these same regions, tropical Atlantic SST variability is associated with changes in large-scale atmospheric conditions, including steering flow, low level vorticity, and humidity, typically associated with tropical cyclogenesis, and tropical cyclone track. The changes in steering flow related to both indices of Atlantic SST anomaly are reproduced by an atmospheric model. The changes in steering flow are also found to be linked to changes in TC translational velocity, and TC tracking. These findings indicate a possible link between tropical Atlantic conditions and cyclone activity in the Indian Ocean mediated through a teleconnection between tropical Atlantic SSTs and large scale atmospheric conditions over the southern Indian Ocean. The teleconnection related to the Benguela Niño region of SST variability was found to consist of a Rossby wave initiated off the coast of South America, and propagating into the Indian Ocean, thereby influencing several atmospheric variables, including steering flow. The teleconnection related to the Atlantic Niño region of SST variability was not well defined, although there was some evidence of a Walker circulation anomaly extending from the equatorial Atlantic over the continent of Africa, and influencing SIO steering flow. Close

• 8. [Article] The weather pattern and trends associated with Gulf Stream turbulent heat loss events

  The weather pattern and trends associated with heat flux events (HFEs) over the Gulf Stream (GS) are examined as part of the CLIMODE project. A large portion of GS turbulent heat loss occurs during distinct ...

  Citation × Citation Citation Abstract Copy Title: The weather pattern and trends associated with Gulf Stream turbulent heat loss events Author: Loyd, Nicholas The weather pattern and trends associated with heat flux events (HFEs) over the Gulf Stream (GS) are examined as part of the CLIMODE project. A large portion of GS turbulent heat loss occurs during distinct synoptic scale events with a duration of one to two days. Forty percent (40%) of wintertime sensible heat loss over the CLIMODE Region (CR) (30°-42° N, 50°-70° W) occurs on 17.5% of days. The overturning convection caused by ocean surface buoyancy loss leads to a deepening mixed layer and the formation of eighteen-degree water (EDW). EDW is a homogenous slab of subtropical mode water with vertically uniform temperature and salinity characteristics. Mode water is formed in regions of large ocean-atmosphere heat exchange and serves as a potential memory source for the climate system. Analysis of sounding data acquired from a ship in the GS region in February and March of 2007 shows a distinct atmospheric vertical thermal profile during HFEs. A typical event day profile exhibits a well mixed boundary layer (BL) featuring a dry adiabatic lapse rate extending up to around 850 millibars (mb). A sharp inversion layer separates the BL from the dry free atmosphere. Satellite imagery confirms that open and closed cell cumulus cloud structures are present during events, which indicate strong surface-based instability and shallow convection. An examination of the National Centers for Environmental Prediction-National Center for Atmospheric Research (NCEP-NCAR) Reanalysis data is performed in order to understand the planetary and synoptic scale weather patterns that induce HFEs. A large 500 mb trough is present over the Western Atlantic Ocean on event days. A surface pressure couplet consisting of high (low) pressure located to the west (northeast) of the CR causes anomalous northwesterly flow that advects cold and dry continental air over the GS. Long term trends in CR Reanalysis data indicate that an increase in sea surface temperature (SST) has significantly increased autumn sensible and latent heat flux since the mid 1960s. Spring is dominated by large decadal variability in thermal and flux fields. Thus, increasing turbulent flux may not lead to greater EDW production since the increased oceanic heat loss serves to remove a seasonal thermocline which is warming over time. Global climate models (GCMs) do not adequately simulate observed CR Reanalysis period climate. The modeled trends in heat flux correlate poorly with Reanalysis. This investigation suggests important areas for potential future research including the effect of turbulent flux on atmosphere and ocean dynamics, and understanding the influence of BL entrainment on heat flux magnitude. Title: The weather pattern and trends associated with Gulf Stream turbulent heat loss events Author: Loyd, Nicholas The weather pattern and trends associated with heat flux events (HFEs) over the Gulf Stream (GS) are examined as part of the CLIMODE project. A large portion of GS turbulent heat loss occurs during distinct synoptic scale events with a duration of one to two days. Forty percent (40%) of wintertime sensible heat loss over the CLIMODE Region (CR) (30°-42° N, 50°-70° W) occurs on 17.5% of days. The overturning convection caused by ocean surface buoyancy loss leads to a deepening mixed layer and the formation of eighteen-degree water (EDW). EDW is a homogenous slab of subtropical mode water with vertically uniform temperature and salinity characteristics. Mode water is formed in regions of large ocean-atmosphere heat exchange and serves as a potential memory source for the climate system. Analysis of sounding data acquired from a ship in the GS region in February and March of 2007 shows a distinct atmospheric vertical thermal profile during HFEs. A typical event day profile exhibits a well mixed boundary layer (BL) featuring a dry adiabatic lapse rate extending up to around 850 millibars (mb). A sharp inversion layer separates the BL from the dry free atmosphere. Satellite imagery confirms that open and closed cell cumulus cloud structures are present during events, which indicate strong surface-based instability and shallow convection. An examination of the National Centers for Environmental Prediction-National Center for Atmospheric Research (NCEP-NCAR) Reanalysis data is performed in order to understand the planetary and synoptic scale weather patterns that induce HFEs. A large 500 mb trough is present over the Western Atlantic Ocean on event days. A surface pressure couplet consisting of high (low) pressure located to the west (northeast) of the CR causes anomalous northwesterly flow that advects cold and dry continental air over the GS. Long term trends in CR Reanalysis data indicate that an increase in sea surface temperature (SST) has significantly increased autumn sensible and latent heat flux since the mid 1960s. Spring is dominated by large decadal variability in thermal and flux fields. Thus, increasing turbulent flux may not lead to greater EDW production since the increased oceanic heat loss serves to remove a seasonal thermocline which is warming over time. Global climate models (GCMs) do not adequately simulate observed CR Reanalysis period climate. The modeled trends in heat flux correlate poorly with Reanalysis. This investigation suggests important areas for potential future research including the effect of turbulent flux on atmosphere and ocean dynamics, and understanding the influence of BL entrainment on heat flux magnitude. Close

• 9. [Article] The effects of an isolated mesoscale island on a stably-stratified airstream

  The perturbation of a stably-stratified flow by irregular terrain is studied utilizing a seven-layer, hydrostatic, and potential enstrophy and energy conserving primitive equation model. The Island of ...

  Citation × Citation Citation Abstract Copy Title: The effects of an isolated mesoscale island on a stably-stratified airstream Author: Kim, Jinwon The perturbation of a stably-stratified flow by irregular terrain is studied utilizing a seven-layer, hydrostatic, and potential enstrophy and energy conserving primitive equation model. The Island of Oahu, Hawaii, and the surrounding ocean area of 130 km x 100 km is chosen as the model topography. The domain is covered with a 5 km x 5 km mesh of 26 x 20 grid points in the horizontal. A cyclic boundary condition is imposed at the lateral boundaries. In order to give finer resolution to the lower atmosphere, an irregularly spaced sigma-coordinate is used in the vertical. Uniform east-north-easterly large-scale geostrophic winds up to the 400 mb level are imposed in order to represent the typical trade-wind condition. The pressure perturbation related to the mass flux divergence associated with the terrain irregularities, and the land-sea temperature difference associated with the different responses to the insolation during the daytime, are found to play a key role in determining the velocity field in the horizontal as well as in the vertical. Asymmetric surface pressure arises, due to the topographically induced vertical motion, with high pressure at the windward slope and low pressure at the downwind slope of the island. Daytime heating of the island induces low pressure on the island surface. This effect is the most significant at the lee side and inland portion of the island where the effect of cold-air advection from the ocean is minimal. At the lee side of the island the negative pressure perturbation induced by the daytime heating favors the establishment of a reverse flow toward the island, but the mountain range at the lee side of the island and prevailing tradewind prevent this low-level inflow from penetrating further inland. At the upwind side of the island, the flow field is mostly determined by topographic slope rather than by the heating of the island surface. The perturbation to the basic flow decreases rapidly upward. But a vertical cross-section of the horizontal divergence and the vertical velocity fields shows well defined wave motions up to the domain top level. The wave motions also appear downstream and upstream of the island with reduced amplitudes away from the island. These suggest the existence of hydrostatic mountain waves forced by the island contour, as was predicted by previous linear studies. The windward tilt of the wave axis shows upward propagation of wave energy, but the wave momentum flux was negligible. Title: The effects of an isolated mesoscale island on a stably-stratified airstream Author: Kim, Jinwon The perturbation of a stably-stratified flow by irregular terrain is studied utilizing a seven-layer, hydrostatic, and potential enstrophy and energy conserving primitive equation model. The Island of Oahu, Hawaii, and the surrounding ocean area of 130 km x 100 km is chosen as the model topography. The domain is covered with a 5 km x 5 km mesh of 26 x 20 grid points in the horizontal. A cyclic boundary condition is imposed at the lateral boundaries. In order to give finer resolution to the lower atmosphere, an irregularly spaced sigma-coordinate is used in the vertical. Uniform east-north-easterly large-scale geostrophic winds up to the 400 mb level are imposed in order to represent the typical trade-wind condition. The pressure perturbation related to the mass flux divergence associated with the terrain irregularities, and the land-sea temperature difference associated with the different responses to the insolation during the daytime, are found to play a key role in determining the velocity field in the horizontal as well as in the vertical. Asymmetric surface pressure arises, due to the topographically induced vertical motion, with high pressure at the windward slope and low pressure at the downwind slope of the island. Daytime heating of the island induces low pressure on the island surface. This effect is the most significant at the lee side and inland portion of the island where the effect of cold-air advection from the ocean is minimal. At the lee side of the island the negative pressure perturbation induced by the daytime heating favors the establishment of a reverse flow toward the island, but the mountain range at the lee side of the island and prevailing tradewind prevent this low-level inflow from penetrating further inland. At the upwind side of the island, the flow field is mostly determined by topographic slope rather than by the heating of the island surface. The perturbation to the basic flow decreases rapidly upward. But a vertical cross-section of the horizontal divergence and the vertical velocity fields shows well defined wave motions up to the domain top level. The wave motions also appear downstream and upstream of the island with reduced amplitudes away from the island. These suggest the existence of hydrostatic mountain waves forced by the island contour, as was predicted by previous linear studies. The windward tilt of the wave axis shows upward propagation of wave energy, but the wave momentum flux was negligible. Close