Low-Level Jet Climatology from Enhanced Rawinsonde Observations at a Site in the Southern Great Plains

1997 ◽  
Vol 36 (10) ◽  
pp. 1363-1376 ◽  
Author(s):  
C. David Whiteman ◽  
Xindi Bian ◽  
Shiyuan Zhong
Keyword(s):  
Great Plains ◽  
Southern Great Plains ◽  
Low Level ◽  
Low Level Jet ◽  
A Site

scholarly journals The Low-Level Jet over the Southern Great Plains Determined from Observations and Reanalyses and Its Impact on Moisture Transport

2015 ◽  
Vol 28 (17) ◽  
pp. 6682-6706 ◽  
Author(s):  
Larry K. Berg ◽  
Laura D. Riihimaki ◽  
Yun Qian ◽  
Huiping Yan ◽  
Maoyi Huang
Keyword(s):  
Great Plains ◽  
Moisture Transport ◽  
Department Of Energy ◽  
Radiosonde Data ◽  
Southern Great Plains ◽  
Low Level ◽  
Convective Clouds ◽  
Atmospheric Radiation Measurement ◽  
Low Level Jet ◽  
Regional Reanalysis

Abstract This study utilizes six commonly used reanalysis products, including the NCEP–Department of Energy Reanalysis 2 (NCEP2), NCEP Climate Forecast System Reanalysis (CFSR), ECMWF interim reanalysis (ERA-Interim), Japanese 25-year Reanalysis Project (JRA-25), Modern-Era Retrospective Analysis for Research and Applications (MERRA), and North American Regional Reanalysis (NARR), to evaluate features of the southern Great Plains low-level jet (LLJ) above the U.S. Department of Energy’s Atmospheric Radiation Measurement Program (ARM) Climate Research Facility (ACRF) Southern Great Plains site. Two sets of radiosonde data are utilized: the six-week Midlatitude Continental Convective Clouds Experiment (MC3E) and a 10-yr period spanning 2001 through 2010. All six reanalyses are compared to MC3E data, while only the NARR, MERRA, and CFSR are compared to the 10-yr data. The reanalyses are able to represent most aspects of the composite LLJ profile, although there is a tendency for each reanalysis to overestimate the wind speed between the nose of the LLJ (at approximately 900 mb) and a pressure level of 700 mb. There are large discrepancies in the number of LLJs observed and derived from the reanalysis, particularly for strong LLJs, leading to an underestimate of the moisture transport associated with LLJs. When the 10-yr period is considered, the NARR and CFSR overestimate and MERRA underestimates the total moisture transport, but all three underestimate the transport associated with strong LLJs by factors of 1.4, 2.0, and 2.7 for CFSR, NARR, and MERRA, respectively. During MC3E there were differences in the patterns of moisture convergence and divergence, but the patterns are more consistent during the 10-yr period.

scholarly journals The Synergistic Relationship between Soil Moisture and the Low-Level Jet and Its Role on the Prestorm Environment in the Southern Great Plains

2010 ◽  
Vol 49 (4) ◽  
pp. 775-791 ◽  
Author(s):  
John D. Frye ◽  
Thomas L. Mote
Keyword(s):  
Soil Moisture ◽  
Great Plains ◽  
Convective Available Potential Energy ◽  
Rank Correlation ◽  
Reanalysis Dataset ◽  
Synoptic Type ◽  
Southern Great Plains ◽  
Low Level ◽  
Convective Parameter ◽  
Low Level Jet

Abstract Changes in low-level moisture alter the convective parameters [e.g., convective available potential energy (CAPE), lifted index (LI), and convective inhibition (CIN)] as a result of alterations in the latent and sensible heat energy exchange. Two sources for low-level moisture exist in the southern Great Plains: 1) moisture advection by the low-level jet (LLJ) from the Gulf of Mexico and 2) evaporation and transpiration from the soils and vegetation in the region. The primary focus of this study is to examine the spatial distribution of soil moisture on a daily basis and to determine the effect it has on the convective parameters. The secondary objective is to investigate how the relationship between soil moisture and convective parameters is altered by the presence of an LLJ. The soil moisture data were obtained through newly developed procedures and advances in technology aboard the Tropical Rainfall Measuring Mission Microwave Imager. The convective parameter data were obtained through the North American Regional Reanalysis dataset. The study examined seven warm seasons (April–September) from 1998 to 2004 and found that the convective environment is more unstable (CAPE > 900 J kg−1, LI < −2°C) but more strongly capped (CIN > 70 J kg−1) on days with an LLJ present. Spearman’s rank correlation analysis showed a less stable atmosphere with increased soil moisture, after soil moisture reached 5%, on most days. Additional analysis determined that on all synoptic-type days the probability of reaching various thresholds of convective intensity increased as soil moisture values increased. The probabilities were even greater on days with an LLJ present than on the days without an LLJ present. An examination of four days representing each synoptic-type day indicates that on the daily scale the intensity of the convective environment is closely related to the high soil moisture and the presence of an LLJ.

Understanding the influence of ENSO on the Great Plains low-level jet in CMIP5 models

2017 ◽  
Vol 51 (4) ◽  
pp. 1537-1558 ◽  
Author(s):  
James F. Danco ◽  
Elinor R. Martin
Keyword(s):  
Great Plains ◽  
Cmip5 Models ◽  
Low Level ◽  
Low Level Jet

scholarly journals Supplementary material to "On the assessment of the moisture transport by the Great Plains low-level jet"

2018 ◽  
Author(s):  
Iago Algarra ◽  
Jorge Eiras-Barca ◽  
Gonzalo Miguez-Macho ◽  
Raquel Nieto ◽  
Luis Gimeno
Keyword(s):  
Great Plains ◽  
Moisture Transport ◽  
Low Level ◽  
Supplementary Material ◽  
Low Level Jet

scholarly journals Future changes in the climatology of the Great Plains low-level jet derived from fine resolution multi-model simulations

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
Ying Tang ◽  
Julie Winkler ◽  
Shiyuan Zhong ◽  
Xindi Bian ◽  
Dana Doubler ◽  
...  
Keyword(s):  
Great Plains ◽  
Model Simulations ◽  
Low Level ◽  
Low Level Jet ◽  
Fine Resolution

scholarly journals Impacts of Modifications to a Local Planetary Boundary Layer Scheme on Forecasts of the Great Plains Low-Level Jet Environment

2018 ◽  
Vol 33 (5) ◽  
pp. 1109-1120 ◽  
Author(s):  
David E. Jahn ◽  
William A. Gallus
Keyword(s):  
Boundary Layer ◽  
Wind Speed ◽  
Planetary Boundary Layer ◽  
Great Plains ◽  
Potential Temperature ◽  
Specific Humidity ◽  
Low Level ◽  
Stable Conditions ◽  
Pbl Scheme ◽  
Low Level Jet

Abstract The Great Plains low-level jet (LLJ) is influential in the initiation and evolution of nocturnal convection through the northward advection of heat and moisture, as well as convergence in the region of the LLJ nose. However, accurate numerical model forecasts of LLJs remain a challenge, related to the performance of the planetary boundary layer (PBL) scheme in the stable boundary layer. Evaluated here using a series of LLJ cases from the Plains Elevated Convection at Night (PECAN) program are modifications to a commonly used local PBL scheme, Mellor–Yamada–Nakanishi–Niino (MYNN), available in the Weather Research and Forecasting (WRF) Model. WRF forecast mean absolute error (MAE) and bias are calculated relative to PECAN rawinsonde observations. The first MYNN modification invokes a new set of constants for the scheme closure equations that, in the vicinity of the LLJ, decreases forecast MAEs of wind speed, potential temperature, and specific humidity more than 19%. For comparison, the Yonsei University (YSU) scheme results in wind speed MAEs 22% lower but specific humidity MAEs 17% greater than in the original MYNN scheme. The second MYNN modification, which incorporates the effects of potential kinetic energy and uses a nonzero mixing length in stable conditions as dependent on bulk shear, reduces wind speed MAEs 66% for levels below the LLJ, but increases MAEs at higher levels. Finally, Rapid Refresh analyses, which are often used for forecast verification, are evaluated here and found to exhibit a relatively large average wind speed bias of 3 m s−1 in the region below the LLJ, but with relatively small potential temperature and specific humidity biases.

scholarly journals A Modified Framework for Quantifying Land–Atmosphere Covariability during Hydrometeorological and Soil Wetness Extremes in Oklahoma

2019 ◽  
Vol 58 (7) ◽  
pp. 1465-1483 ◽  
Author(s):  
Ryann A. Wakefield ◽  
Jeffrey B. Basara ◽  
Jason C. Furtado ◽  
Bradley G. Illston ◽  
Craig. R. Ferguson ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Great Plains ◽  
Hot Spot ◽  
Extreme Rainfall ◽  
Southern Great Plains ◽  
Low Level ◽  
Oklahoma Mesonet ◽  
Humidity Index ◽  
Grid Points ◽  
Regional Reanalysis

AbstractGlobal “hot spots” for land–atmosphere coupling have been identified through various modeling studies—both local and global in scope. One hot spot that is common to many of these analyses is the U.S. southern Great Plains (SGP). In this study, we perform a mesoscale analysis, enabled by the Oklahoma Mesonet, that bridges the spatial and temporal gaps between preceding local and global analyses of coupling. We focus primarily on east–west variations in seasonal coupling in the context of interannual variability over the period spanning 2000–15. Using North American Regional Reanalysis (NARR)-derived standardized anomalies of convective triggering potential (CTP) and the low-level humidity index (HI), we investigate changes in the covariance of soil moisture and the atmospheric low-level thermodynamic profile during seasonal hydrometeorological extremes. Daily CTP and HI z scores, dependent upon climatology at individual NARR grid points, were computed and compared to in situ soil moisture observations at the nearest mesonet station to provide nearly collocated annual composites over dry and wet soils. Extreme dry and wet year CTP and HI z-score distributions are shown to deviate significantly from climatology and therefore may constitute atmospheric precursors to extreme events. The most extreme rainfall years differ from climatology but also from one another, indicating variability in the strength of land–atmosphere coupling during these years. Overall, the covariance between soil moisture and CTP/HI is much greater during drought years, and coupling appears more consistent. For example, propagation of drought during 2011 occurred under antecedent CTP and HI conditions that were identified by this study as being conducive to positive dry feedbacks demonstrating potential utility of this framework in forecasting regional drought propagation.

scholarly journals Climatic factors contributing to long-term variations of fine dust concentration in the United States

2017 ◽  
Author(s):  
Bing Pu ◽  
Paul Ginoux
Keyword(s):  
Great Plains ◽  
The United States ◽  
Dust Concentration ◽  
Dust Particles ◽  
Positive Trend ◽  
Fine Dust ◽  
Low Level ◽  
Low Level Jet ◽  
Long Term Variations

Abstract. High concentration of dust particles can cause respiratory problems and increase non-accidental mortality. Studies found fine dust (with aerodynamic diameter less than 2.5 microns) is an important component of the total PM2.5 mass in the western and central U.S. in spring and summer and has positive trends. This work examines factors influencing long-term variations of fine dust concentration in the U.S. using station data from the Interagency Monitoring Protected Visual Environments (IMPROVE) network during 1990–2015. The variations of the fine dust concentration can be largely explained by the variations of precipitation, surface bareness, and 10 m wind speed. Moreover, including convective parameters such as convective inhibition (CIN) and convective available potential energy (CAPE) better explains the variations and trends over the Great Plains from spring to fall. While the positive trend of fine dust concentration in the Southwest in spring is associated with precipitation deficit, the increasing of fine dust over the central Great Plains in summer is largely associated with an enhancing of CIN and a weakening of CAPE, which are related to increased atmospheric stability due to surface drying and lower troposphere warming. The positive trend of the Great Plains low-level jet also contributes to the increasing of fine dust concentration in the central Great Plains in summer via its connections with surface winds and CIN. Summer dusty days in the central Great Plains are usually associated with a westward extension of the North Atlantic subtropical high that intensifies the Great Plains low-level jet and also results in a stable atmosphere with subsidence and reduced precipitation.

scholarly journals Impacts of Gulf of Mexico SST Anomalies on Southern Plains Freezing Precipitation: ARW Sensitivity Study of the 28–30 January 2010 Winter Storm

2016 ◽  
Vol 55 (1) ◽  
pp. 119-143 ◽  
Author(s):  
Esther D. Mullens ◽  
Lance M. Leslie ◽  
Peter J. Lamb
Keyword(s):  
Gulf Of Mexico ◽  
Great Plains ◽  
Sensitivity Study ◽  
Ice Storm ◽  
Storm Events ◽  
Winter Storm ◽  
Southern Plains ◽  
Southern Great Plains ◽  
Low Level ◽  
Ice Storms

AbstractIce storms are an infrequent but significant hazard in the U.S southern Great Plains. Common synoptic profiles for freezing precipitation reveal advection of low-level warm moist air from the Gulf of Mexico (GOM), above a shallow Arctic air mass ahead of a midlevel trough. Because the GOM is the proximal basin and major moisture source, this study investigates impacts of varying GOM sea surface temperature (SST) on the thermodynamic evolution of a winter storm that occurred during 28–30 January 2010, with particular emphasis on the modulation of freezing precipitation. A high-resolution, nested ARW sensitivity study with a 3.3-km inner domain is performed, using six representations of GOM SST, including control, climatological mean, uniform ±2°C from control, and physically constrained upper- and lower-bound basin-average anomalies from a 30-yr dataset. The simulations reveal discernable impacts of SST on the warm-layer inversion, precipitation intensity, and low-level dynamics. Whereas total precipitation for the storm increased monotonically with SST, the freezing-precipitation response was more varied and nonlinear, with the greatest accumulation decreases occurring for the coolest SST perturbation, particularly at moderate precipitation rates. Enhanced precipitation and warm-layer intensity promoted by warmer SST were offset for the highest perturbations by deepening of the weak 850-hPa low circulation and faster eastward progression associated with enhanced baroclinicity and diabatic generation of potential vorticity. Air-parcel trajectories terminating within the freezing-precipitation region were examined to identify airmass sources and modification. These results suggest that GOM SST can affect the severity of concurrent ice-storm events in the southern Great Plains, with warmer basin SST potentially exacerbating the risk of damaging ice accumulations.

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