scholarly journals Climatology of the planetary boundary layer over the continental United States and Europe

2012 ◽  
Vol 117 (D17) ◽  
pp. n/a-n/a ◽  
Author(s):  
Dian J. Seidel ◽  
Yehui Zhang ◽  
Anton Beljaars ◽  
Jean-Christophe Golaz ◽  
Andrew R. Jacobson ◽  
...  
Keyword(s):  
United States ◽  
Boundary Layer ◽  
Planetary Boundary Layer

scholarly journals Aerosol optical properties in the southeastern United States in summer – Part 1: Hygroscopic growth

2016 ◽  
Vol 16 (8) ◽  
pp. 4987-5007 ◽  
Author(s):  
Charles A. Brock ◽  
Nicholas L. Wagner ◽  
Bruce E. Anderson ◽  
Alexis R. Attwood ◽  
Andreas Beyersdorf ◽  
...  
Keyword(s):  
United States ◽  
Boundary Layer ◽  
Planetary Boundary Layer ◽  
Layer Structure ◽  
Southeastern United States ◽  
Organic Aerosol ◽  
Hygroscopic Growth ◽  
Aerosol Composition ◽  
Optical Extinction ◽  
Southeastern Us

Abstract. Aircraft observations of meteorological, trace gas, and aerosol properties were made during May–September 2013 in the southeastern United States (US) under fair-weather, afternoon conditions with well-defined planetary boundary layer structure. Optical extinction at 532 nm was directly measured at relative humidities (RHs) of  ∼  15,  ∼  70, and  ∼  90 % and compared with extinction calculated from measurements of aerosol composition and size distribution using the κ-Köhler approximation for hygroscopic growth. The calculated enhancement in hydrated aerosol extinction with relative humidity, f(RH), calculated by this method agreed well with the observed f(RH) at  ∼  90 % RH. The dominance of organic aerosol, which comprised 65 ± 10 % of particulate matter with aerodynamic diameter  <  1 µm in the planetary boundary layer, resulted in relatively low f(RH) values of 1.43 ± 0.67 at 70 % RH and 2.28 ± 1.05 at 90 % RH. The subsaturated κ-Köhler hygroscopicity parameter κ for the organic fraction of the aerosol must have been  <  0.10 to be consistent with 75 % of the observations within uncertainties, with a best estimate of κ  =  0.05. This subsaturated κ value for the organic aerosol in the southeastern US is broadly consistent with field studies in rural environments. A new, physically based, single-parameter representation was developed that better described f(RH) than did the widely used gamma power-law approximation.

scholarly journals Estimating Planetary Boundary Layer Heights from NOAA Profiler Network Wind Profiler Data

2015 ◽  
Vol 32 (9) ◽  
pp. 1545-1561 ◽  
Author(s):  
A. Molod ◽  
H. Salmun ◽  
M. Dempsey
Keyword(s):  
United States ◽  
Boundary Layer ◽  
Planetary Boundary Layer ◽  
Richardson Number ◽  
Wind Profiler ◽  
Clear Sky ◽  
Hourly Temperature ◽  
Central United States ◽  
Sky Conditions ◽  
Profiler Data

AbstractAn algorithm was developed to estimate planetary boundary layer (PBL) heights from hourly archived wind profiler data from the NOAA Profiler Network (NPN) sites located throughout the central United States. Unlike previous studies, the present algorithm has been applied to a long record of publicly available wind profiler signal backscatter data. Under clear-sky conditions, summertime averaged hourly time series of PBL heights compare well with Richardson number–based estimates at the few NPN stations with hourly temperature measurements. Comparisons with estimates based on clear-sky reanalysis show that the wind profiler (WP) PBL heights are lower by approximately 250–500 m. The geographical distribution of daily maximum PBL heights corresponds well with the expected distribution based on patterns of surface temperature and soil moisture. Wind profiler PBL heights were also estimated under mostly cloudy-sky conditions, and are generally comparable to the Richardson number–based PBL heights and higher than the reanalysis PBL heights. WP PBL heights have a smaller clear–cloudy condition difference than either of the other two. The algorithm presented here is shown to provide a reliable summertime climatology of daytime hourly PBL heights throughout the central United States.

Subseasonal prediction of springtime Pacific-North American transport using upper-level wind forecasts

2021 ◽  
Author(s):  
John R. Albers ◽  
Amy H. Butler ◽  
Melissa L. Breeden ◽  
Andrew O. Langford ◽  
George N. Kiladis
Keyword(s):  
United States ◽  
Boundary Layer ◽  
Planetary Boundary Layer ◽  
Zonal Wind ◽  
North American ◽  
The United States ◽  
Anomalous Transport ◽  
Water Vapor Transport ◽  
Pacific North American ◽  
Upper Level

&lt;p&gt;Mass transport is important to many aspects of Pacific-North American climate, including stratosphere-to-troposphere transport of ozone to the planetary boundary layer, which has negative impacts on human health, and water vapor transport, which contributes to precipitation variability. Here, subseasonal forecasts (forecasts 3-6 weeks into the future) of Pacific jet variability are used to predict stratosphere-to-troposphere transport (STT) and tropical-to-extratropical moisture exports (TME) during boreal spring over the Pacific-North American region. To do this, we consider a very simple conditional probability: if 200 hPa zonal winds have a high (positive or negative) loading on a particular 200 hPa Pacific basin zonal wind pattern, then what will the corresponding shift in the probability of STT or TME be during those time periods? We first answer this question in the context of a retrospective analysis, which allows us to understand the regionality of STT and TME for different jet patterns. Then, using the retrospective results as a guide, we utilize zonal wind hindcasts from the European Centre for Medium-Range Weather Forecasts Integrated Forecasting System (taken from the S2S Prediction Project) to test whether STT and TME over specific geographic regions may be predictable for subseasonal forecast leads (weeks 3-6). For both analyses, STT and TME are taken from the ETH-Z&amp;#252;rich Feature-based climatology database, which allows us to apply a single, self-consistent measure of transport for both the retrospective (1979-2016) and hindcast (1997-2016) analysis periods.&lt;/p&gt;&lt;p&gt;We find that large anomalies in STT to the mid-troposphere over the North Pacific, TME to the west coast of the United States, and TME over Japan are found to have the best potential for subseasonal predictability using upper-level wind forecasts. STT to the planetary boundary layer over the intermountain west of the United States is also potentially predictable for subseasonal leads, but likely only in the context of shifts in the probability of extreme events. While STT and TME forecasts match verifications quite well in terms of spatial structure and anomaly sign, the number of anomalous transport days is underestimated compared to observations. The underestimation of the number of anomalous transport days exhibits a strong seasonal cycle, which becomes progressively worse as spring progresses into summer.&lt;/p&gt;

scholarly journals Effects of Implementing MODIS Land Cover and Albedo in MM5 at Two Contrasting U.S. Regions

2006 ◽  
Vol 7 (5) ◽  
pp. 1043-1060 ◽  
Author(s):  
Ismail Yucel
Keyword(s):  
United States ◽  
Boundary Layer ◽  
Land Cover ◽  
Planetary Boundary Layer ◽  
Land Surface ◽  
Surface Wind ◽  
The United States ◽  
Error Reduction ◽  
Near Surface ◽  
Temperature And Humidity

Abstract This study implements a new land-cover classification and surface albedo from the Moderate Resolution Imaging Spectroradiometer (MODIS) in the fifth-generation Pennsylvania State University–National Center for Atmospheric Research (PSU–NCAR) Mesoscale Model (MM5) and investigates its effects on regional near-surface atmospheric state variables as well as the planetary boundary layer evolution for two dissimilar U.S. regions. Surface parameter datasets are determined by translating the 17-category MODIS classes into the U.S. Geological Survey (USGS) and Simple Biosphere (SiB) categories available for use in MM5. Changes in land-cover specification or associated parameters affected surface wind, temperature, and humidity fields, which, in turn, resulted in perceivable alterations in the evolving structure of the planetary boundary layer. Inclusion of the MODIS albedo into the simulations enhanced these impacts further. Area-averaged comparisons with ground measurements showed remarkable improvements in near-surface temperature and humidity at both study areas when MM5 is initialized with MODIS land-cover and albedo data. Influence of both MODIS surface datasets is more significant at a semiarid location in the southwest of the United States than it is in a humid location in the mid-Atlantic region. Intense summertime surface heating at the semiarid location creates favorable conditions for strong land surface forcing. For example, when the simulations include MODIS land cover and MODIS albedo, respective error reduction rates were 6% and 11% in temperature and 2% and 2.5% in humidity in the southwest of the United States. Error reduction rates in near-surface atmospheric fields are considered important in the design of mesoscale weather simulations.

scholarly journals Clustering of Observed Diurnal Cycles of Precipitation over the United States for Evaluation of a WRF Multiphysics Regional Climate Ensemble

2017 ◽  
Vol 30 (22) ◽  
pp. 9267-9286 ◽  
Author(s):  
P. A. Mooney ◽  
C. Broderick ◽  
C. L. Bruyère ◽  
F. J. Mulligan ◽  
A. F. Prein
Keyword(s):  
United States ◽  
Boundary Layer ◽  
Planetary Boundary Layer ◽  
Diurnal Cycle ◽  
Regional Climate ◽  
Wrf Model ◽  
The United States ◽  
Total Precipitation ◽  
Precipitation Frequency ◽  
Diurnal Cycle Of Precipitation

The diurnal cycle of precipitation during the summer season over the contiguous United States is examined in eight distinct regions. These were identified using cluster analysis applied to the diurnal cycle characteristics at 2141 rainfall gauges over the 10-yr period 1991–2000. Application of the clustering technique provides a physically meaningful way of identifying regions for comparison of model results with observations. The diurnal cycle for each region is specified in terms of 1) total precipitation, 2) frequency of precipitation occurrence, and 3) intensity of precipitation per occurrence on an hourly basis averaged over the 10-yr period. The amplitude and phase of each element of the diurnal cycle was obtained from harmonic analysis and has been compared with the results of a 24-member multiphysics ensemble of simulations produced by the Weather Research and Forecast (WRF) Model on a region-by-region basis. Three cumulus schemes, two radiation schemes, two microphysics schemes, and two planetary boundary layer schemes were included in the ensemble. Simulations of total precipitation showed reasonable agreement with observations in regions where the diurnal cycle is directly influenced by solar radiation, (e.g., the U.S. Southeast), but they were less successful in regions where other factors influence the diurnal cycle (e.g., the central United States). The diurnal cycle of precipitation frequency and intensity showed substantial biases in the simulations of all eight regions, namely, overestimation of occurrences and underestimation of intensities. Simulations were sensitive to the cumulus and radiation schemes but were largely insensitive to either microphysics or planetary boundary layer schemes.

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