Analysis of Near-Surface Atmospheric Measurements Obtained During CBLAST-LOW

2006 ◽  
Author(s):  
James B. Edson
Keyword(s):  
Atmospheric Measurements ◽  
Near Surface

scholarly journals Approaches for predicting wind turbine hub-height turbulence metrics

2021 ◽  
Author(s):  
Hannah Livingston ◽  
Nicola Bodini ◽  
Julie K. Lundquist
Keyword(s):  
Wind Turbine ◽  
Control Strategies ◽  
Atmospheric Stability ◽  
Ground Level ◽  
Atmospheric Measurements ◽  
Large Variability ◽  
Near Surface ◽  
Energy Applications ◽  
Main Driver ◽  
Surface Measurements

Abstract. Hub-height turbulence is essential for a variety of wind energy applications, ranging from wind plant siting to wind turbine control strategies. Because deploying hub-height meteorological towers can be a challenge, alternative ways to estimate hub-height turbulence are desired. In this paper, we assess to what degree hub-height turbulence can be estimated via other hub-height variables or ground-level atmospheric measurements in complex terrain, using observations from three meteorological towers at the Perdigão and WFIP2 field campaigns. We find a large variability across the three considered towers when trying to model hub-height turbulence intensity (TI) and turbulence kinetic energy (TKE) from hub-height or near-surface measurements of either wind speed, TI, or TKE. Moreover, we find that based on the characteristics of the specific site, atmospheric stability and upwind fetch either determine a significant variability in hub-height turbulence or are not a main driver of the variability in hub-height TI and TKE. Our results highlight how hub-height turbulence is simultaneously sensitive to numerous different factors, so that no simple and universal relationship can be determined to vertically extrapolate turbulence from near-surface measurements, or model it from other hub-height variables when considering univariate relationships. We suggest that a multivariate approach should instead be considered, possibly leveraging the capabilities of machine learning nonlinear algorithms.

scholarly journals Climate of the Greenland ice sheet using a high-resolution climate model – Part 1: Evaluation

2010 ◽  
Vol 4 (2) ◽  
pp. 561-602 ◽  
Author(s):  
J. Ettema ◽  
M. R. van den Broeke ◽  
E. van Meijgaard ◽  
W. J. van de Berg ◽  
J. E. Box ◽  
...  
Keyword(s):  
Surface Energy ◽  
Climate Model ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Specific Humidity ◽  
Katabatic Wind ◽  
Turbulent Heat ◽  
Atmospheric Measurements ◽  
Near Surface ◽  
Downward Longwave Radiation

Abstract. A simulation of 51 years (1957–2008) has been performed over Greenland using the regional atmospheric climate model RACMO2 at a horizontal grid spacing of 11 km forced by ECMWF analysis products. To better represent processes affecting ice sheet surface mass balance, such as melt water refreezing and penetration, an additional snow/ice surface module has been developed and implemented into the surface parameterisation of RACMO2v1. The temporal evolution and climatology of the model is evaluated with in situ coastal and ice sheet atmospheric measurements of near-surface variables and surface energy balance components. The bias for the near-surface air temperature (0.9 °C), specific humidity (0.1 g kg−1), wind speed (0.3 m s−1) as well as for radiative (2.5 W m−2 for net radiation) and turbulent heat fluxes shows that the model is in good accordance with available observations. The modeled surface energy budget underestimates the downward longwave radiation and overestimates the sensible heat flux. Due to their compensating effect, the averaged 2 m temperature bias is less than −0.9°C. The katabatic wind circulation is well captured by the model.

scholarly journals The effects of snow and salt on ice table stability in University Valley, Antarctica

2017 ◽  
Vol 30 (1) ◽  
pp. 67-78 ◽  
Author(s):  
K.E. Williams ◽  
J.L. Heldmann ◽  
Christopher P. McKay ◽  
Michael T. Mellon
Keyword(s):  
Soil Column ◽  
Soil Surface ◽  
Dry Valleys ◽  
Resolution Time ◽  
Atmospheric Measurements ◽  
Near Surface ◽  
Time Marching ◽  
Saturation Vapour Pressure ◽  
Snow Model ◽  
The Antarctic

AbstractThe Antarctic Dry Valleys represent a unique environment where it is possible to study dry permafrost overlaying an ice-rich permafrost. In this paper, two opposing mechanisms for ice table stability in University Valley are addressed: i) diffusive recharge via thin seasonal snow deposits and ii) desiccation via salt deposits in the upper soil column. A high-resolution time-marching soil and snow model was constructed and applied to University Valley, driven by meteorological station atmospheric measurements. It was found that periodic thin surficial snow deposits (observed in University Valley) are capable of drastically slowing (if not completely eliminating) the underlying ice table ablation. The effects of NaCl, CaCl2 and perchlorate deposits were then modelled. Unlike the snow cover, however, the presence of salt in the soil surface (but no periodic snow) results in a slight increase in the ice table recession rate, due to the hygroscopic effects of salt sequestering vapour from the ice table below. Near-surface pore ice frequently forms when large amounts of salt are present in the soil due to the suppression of the saturation vapour pressure. Implications for Mars high latitudes are discussed.

scholarly journals Frequency and Characteristics of Inland Advecting Sea Breezes in the Southeast United States

Atmosphere ◽  
2021 ◽  
Vol 12 (8) ◽  
pp. 950
Author(s):  
Brian Viner ◽  
Stephen Noble ◽  
Jian-Hua Qian ◽  
David Werth ◽  
Paul Gayes ◽  
...  
Keyword(s):  
Sea Breeze ◽  
Dew Point ◽  
Savannah River ◽  
Atmospheric Measurements ◽  
Southeast United States ◽  
Near Surface ◽  
Sea Breezes ◽  
Synoptic Classification ◽  
Synoptic Conditions ◽  
Cloud Development

Sea breezes have been observed to move inland over 100 km. These airmasses can be markedly different from regional airmasses, creating a shallow layer with differences in humidity, wind, temperature and aerosol characteristics. To understand their influence on boundary layer and cloud development on subsequent days, we identify their frequency and characteristics. We visually identified sea breeze fronts on radar passing over the Savannah River Site (SRS) between March and October during 2015–2019. The SRS is ~150 km from the nearest coastal location; therefore, our detection suggests further inland penetration. We also identified periods when sea breeze fronts may have passed but were not visually observed on radar due to the shallow sea breeze airmass remaining below the radar beam elevation that ranges between approximately 1–8 km depending on the beam angle and radar source (Columbia, SC or Charleston, SC). Near-surface atmospheric measurements indicate that the dew point temperature increases, the air temperature decreases, the variation in wind direction decreases and the aerosol size increases after sea breeze frontal passage. A synoptic classification procedure also identified that inland moving sea breezes are more commonly observed when the synoptic conditions include weak to moderate offshore winds with an average of 35 inland sea breezes occurring each year, focused primarily in the months of April, May and June.

scholarly journals Implementation of HONO into the chemistry-climate model CHASER (V4.0): roles in tropospheric chemistry

2021 ◽  
Author(s):  
Phuc Thi Minh Ha ◽  
Yugo Kanaya ◽  
Fumikazu Taketani ◽  
Maria Dolores Andrés Hernández ◽  
Benjamin Schreiner ◽  
...  
Keyword(s):  
Climate Model ◽  
Lower Troposphere ◽  
Monitoring Network ◽  
Heterogeneous Reactions ◽  
Tropospheric Chemistry ◽  
Ozone Monitoring Instrument ◽  
Atmospheric Measurements ◽  
Cloud Particle ◽  
Near Surface ◽  
Airborne Measurements

Abstract. Nitrous acid (HONO) is an important atmospheric gas given its contribution to the cycles of NOx and HOx, but its role in global atmospheric photochemistry is not fully understood. This study, for the first time, implemented three pathways of HONO formation in the chemistry-climate model CHASER (MIROC-ESM) to explore three physical phenomena: gas-phase kinetic reactions (GRs), direct emission (EM), and heterogeneous reactions on cloud/aerosol particles (HRs). We evaluated the simulations by the atmospheric measurements from the OMI (Ozone Monitoring Instrument), EANET (Acid Deposition Monitoring Network in eastern Asia) / EMEP (European Monitoring and Evaluation Programme) ground-based stationary observations, observations from the ship R/V Mirai, and aircraft-based measurements by ATom1 (atmospheric tomography) and EMeRGe-Asia-2018 (Effect of Megacities on the Transport and Transformation of Pollutants on the Regional to Global scales). We showed that the inclusion of the HONO chemistry in the modeling process reduces the model bias against the measurements for PM2.5, NO3−/HNO3, NO2, OH, O3, and CO, especially in the lower troposphere and the North Pacific (NP) region. We found that the retrieved global abundance of tropospheric HONO was 1.4 TgN. Of the three source pathways, HRs and EM contributed 63 % and 26 % to the net HONO production, respectively. We also observed that, reactions on the aerosol surfaces contributed larger amounts of HONO (51 %) than those on the cloud surfaces (12 %). The model exhibited significant negative biases for daytime HONO in the Asian off-coast region, compared with the airborne measurements by EMeRGe-Asia-2018, indicating the existence of unknown daytime HONO sources. Strengthening of aerosol uptake of NO2 near-surface and in the middle troposphere, cloud uptake, and direct HONO emission are all potential yet-unknown HONO sources. We also found that the simulated HONO abundance and its impact on NOx-O3 chemistry are sensitive to the yield of the heterogeneous conversion of NO2 to HONO (vs. HNO3). Inclusion of HONO reduces global tropospheric NOx (NO + NO2) levels by 20.4 %, thereby weakening the tropospheric oxidizing capacity, which in turn, increases CH4 lifetime (13 %) and CO abundance (8 %). HRs on the surfaces of cloud particles, which have been neglected in previous modeling studies, are the main drivers of these impacts. This effect is particularly salient for the substantial reductions of levels of OH (40–67 %) and O3 (30–45 %) in the NP region during summer given the significant reduction of NOx level (50–95 %). In contrast, HRs on aerosol surfaces in China (Beijing) enhance OH and O3 winter mean levels by 600–1700 % and 10–33 %, respectively, with regards to their minima in winter. Overall, our findings suggest that a global model that does not consider HONO heterogeneous mechanisms (especially HRs on cloud particle surfaces) may erroneously predict the effect of HONO in remote areas and polluted regions.

scholarly journals Using near-surface atmospheric measurements as a proxy for quantifying field-scale soil gas flux

2020 ◽  
Author(s):  
Andrew Barkwith ◽  
Stan E. Beaubien ◽  
Thomas Barlow ◽  
Karen Kirk ◽  
Thomas R. Lister ◽  
...  
Keyword(s):  
Soil Gas ◽  
New Method ◽  
Horizontal Wind ◽  
Atmospheric Conditions ◽  
Field Scale ◽  
Atmospheric Measurements ◽  
Gas Flux ◽  
Near Surface ◽  
Gas Fluxes ◽  
Soil Gas Flux

Abstract. We present a new method for deriving surface soil gas flux at the field scale, which is less field-work intensive than traditional chamber techniques and less expensive than those derived from airborne or space surveys. The technique uses aspects of chamber and micrometeorological methods combined with a mobile platform and GPS to rapidly derive soil gas fluxes at the field-scale. There are several assumptions in using this method, which will be most accurate under stable atmospheric conditions with little horizontal wind flow. Results show that soil gas fluxes, when averaged across a field site, are highly comparable between the method presented and traditional chamber acquisition techniques. Atmospheric dilution is found to reduce the range of flux values under the open field-scale method, when compared to chamber derived results. Under ideal atmospheric conditions it may be possible to use the presented method to derive soil gas flux at an individual point, however this requires further investigation. The new method for deriving soil-atmosphere gas exchange at the field-scale could be useful for a number of applications including quantification of CCS leakage, diffuse degassing in volcanic and geothermal areas and greenhouse-gas emissions.

scholarly journals Climate of the Greenland ice sheet using a high-resolution climate model – Part 1: Evaluation

2010 ◽  
Vol 4 (4) ◽  
pp. 511-527 ◽  
Author(s):  
J. Ettema ◽  
M. R. van den Broeke ◽  
E. van Meijgaard ◽  
W. J. van de Berg ◽  
J. E. Box ◽  
...  
Keyword(s):  
Surface Energy ◽  
Climate Model ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Specific Humidity ◽  
Katabatic Wind ◽  
Turbulent Heat ◽  
Atmospheric Measurements ◽  
Near Surface ◽  
Downward Longwave Radiation

Abstract. A simulation of 51 years (1957–2008) has been performed over Greenland using the regional atmospheric climate model (RACMO2/GR) at a horizontal grid spacing of 11 km and forced by ECMWF re-analysis products. To better represent processes affecting ice sheet surface mass balance, such as meltwater refreezing and penetration, an additional snow/ice surface module has been developed and implemented into the surface part of the climate model. The temporal evolution and climatology of the model is evaluated with in situ coastal and ice sheet atmospheric measurements of near-surface variables and surface energy balance components. The bias for the near-surface air temperature (−0.8 °C), specific humidity (0.1 g kg−1), wind speed (0.3 m s−1) as well as for radiative (2.5 W m−2 for net radiation) and turbulent heat fluxes shows that the model is in good accordance with available observations on and around the ice sheet. The modelled surface energy budget underestimates the downward longwave radiation and overestimates the sensible heat flux. Due to their compensating effect, the averaged 2 m temperature bias is small and the katabatic wind circulation well captured by the model.

Benthic foraminiferal zonation in deep-water carbonate platform margin environments, northern Little Bahama Bank

1988 ◽  
Vol 62 (01) ◽  
pp. 1-8 ◽  
Author(s):  
Ronald E. Martin
Keyword(s):  
Deep Water ◽  
Benthic Foraminifera ◽  
Carbonate Platform ◽  
Sedimentary Facies ◽  
Depositional Environments ◽  
Near Surface ◽  
Sediment Gravity Flows ◽  
Gravity Flows ◽  
Platform Margin ◽  
Water Carbonate

The utility of benthic foraminifera in bathymetric interpretation of clastic depositional environments is well established. In contrast, bathymetric distribution of benthic foraminifera in deep-water carbonate environments has been largely neglected. Approximately 260 species and morphotypes of benthic foraminifera were identified from 12 piston core tops and grab samples collected along two traverses 25 km apart across the northern windward margin of Little Bahama Bank at depths of 275-1,135 m. Certain species and operational taxonomic groups of benthic foraminifera correspond to major near-surface sedimentary facies of the windward margin of Little Bahama Bank and serve as reliable depth indicators. Globocassidulina subglobosa, Cibicides rugosus, and Cibicides wuellerstorfi are all reliable depth indicators, being most abundant at depths >1,000 m, and are found in lower slope periplatform aprons, which are primarily comprised of sediment gravity flows. Reef-dwelling peneroplids and soritids (suborder Miliolina) and rotaliines (suborder Rotaliina) are most abundant at depths <300 m, reflecting downslope bottom transport in proximity to bank-margin reefs. Small miliolines, rosalinids, and discorbids are abundant in periplatform ooze at depths <300 m and are winnowed from the carbonate platform. Increased variation in assemblage diversity below 900 m reflects mixing of shallow- and deep-water species by sediment gravity flows.

Sign in / Sign up

Export Citation Format

Share Document