Sensitivity of Low-Level Jets to Land-Use and Land-Cover Change over the Continental U.S.

Nikolic, Jovanka; Zhong, Shiyuan; Pei, Liang; Bian, Xindi; Heilman, Warren E.; Charney, Joseph J.

doi:10.3390/atmos10040174

Cited by 10 publications

(6 citation statements)

References 35 publications

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“…Both the frequency of NOI and LLJs present increasing trends before 2012 and decreasing trends thereafter, which was likely related to urbanisation. Previous studies have shown that urbanisation has large effects on the frequency of LLJs by changing surface conditions (roughness and soil moisture) and further affecting the turbulence and geostrophic wind speed (McCorcle, 1988;Fast and McCorcle, 1990;Kallistratova, 2008;Nikolic et al, 2019;Ziemann et al, 2019). Kallistratova (2008) and Nikolic et al (2019) pointed out that negative correlation was found between urban areas and the frequency of LLJs.…”

Section: Long-term Trends Of Noi Eventsmentioning

confidence: 98%

Quantitative impacts of vertical transport on the long-term trend of nocturnal ozone increase over the Pearl River Delta region during 2006–2019

You

Jia

et al. 2023

Atmos. Chem. Phys.

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Abstract. The Pearl River Delta (PRD) region in southern China has been subject to severe ozone (O3) pollution during daytime and anomalous nocturnal O3 increase (NOI) during nighttime. In this study, the spatiotemporal variation of NOI events in the PRD region from 2006 to 2019 is comprehensively analysed, and the role of vertical transport in the occurrence of NOI events is quantified based on observed surface and vertical O3 and the fifth-generation European Centre for Medium-Range Weather Forecasts (ECMWF) reanalysis (ERA5) dataset. The results show that the average annual frequency of NOI events in the whole PRD region during the 14 year period is estimated to be 53 ± 16 d yr−1, with an average of 58 ± 11 µg m−3 for the nocturnal O3 peak (NOP) concentration. Low-level jets (LLJs) are the main meteorological processes triggering NOI events, explaining on average 61 % of NOI events. Annual NOI events exhibit an upward trend before 2011 (4.70 d yr−1) and a downward trend thereafter (−0.72 d yr−1), which is consistent with the annual variation of LLJs (r=0.88, p<0.01). Although the contribution of convective storms (Conv) to NOI events is relatively small with an average value of 11 %, Conv-induced NOI events steadily increased at a rate of 0.26 d yr−1 during this 14 year period due to the impact of urbanisation. Seasonally, a relatively higher frequency of NOI events is observed in spring and autumn, which is consistent with the seasonal pattern of LLJs and maximum daily 8 h average (MDA8) O3. Spatially, NOI events are frequent in the eastern PRD, which agrees well with the spatial distribution of the frequency of LLJs and partially overlaps with the distribution of MDA8 O3 concentration, suggesting that vertical transport plays a more important role in NOI events than daytime O3 concentration. The Weather Research and Forecasting (WRF) model coupled with the Community Multiscale Air Quality (CMAQ) model and the observed vertical O3 profiles are further applied to illustrate the mechanisms of NOI formation caused by LLJs and Conv. The results confirm that both LLJs and Conv trigger NOI events by inducing downdrafts with the difference being that LLJs induce downdrafts by wind shear, while Conv by compensating downdrafts. Through observational and modelling analysis, this study presents the long-term (2006–2019) trends of NOI events in the PRD region and quantifies the contribution of meteorological processes for the first time, emphasising the importance of vertical transport, as well as daytime O3 concentration for the occurrence of NOI events.

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Section: Long-term Trends Of Noi Eventsmentioning

confidence: 98%

Quantitative impacts of vertical transport on the long-term trend of nocturnal ozone increase over the Pearl River Delta region during 2006–2019

You

Jia

et al. 2023

Atmos. Chem. Phys.

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“…Given the central role of GPLLJs in modulating regional hydroclimate and in the context of potential ongoing changes to GPLLJ frequency over time (e.g., Cook et al 2008; Barandiaran et al 2013;Nikolic et al 2019), subseasonal UC:C GPLLJ event ratios are deserving of a more careful and complete analysis. Moreover, both C and UC jets, in their own different ways, affect wind energy potential and severe weather generation (e.g., Arritt et al 1997;Berg et al 2015;Reif and Bluestein 2017).…”

mentioning

confidence: 99%

The Role of Upper-Level Coupling on Great Plains Low-Level Jet Structure and Variability

Burrows

Ferguson

Bosart

2020

Journal of the Atmospheric Sciences

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The Great Plains (GP) southerly nocturnal low-level jet (GPLLJ) is a dominant contributor to the region’s warm season (May–September) mean and extreme precipitation, wind energy generation and severe weather outbreaks—including mesoscale convective systems. The spatiotemporal structure, variability, and impact of individual GPLLJ events are closely related to their degree of upper-level synoptic coupling, which varies from strong coupling in synoptic trough/ridge environments to weak coupling in quiescent, synoptic ridge environments. Here, we apply an objective dynamic classification of GPLLJ upper-level coupling and fully characterize strongly coupled (C) and relatively uncoupled (UC) GPLLJs from the perspective of the ground-based observer. Through composite analyses of C and UC GPLLJ event samples taken from the CERA-20C, we address how the frequency of these jet types, as well as their inherent weather- and climate-relevant characteristics, including: wind speed, direction, and shear; atmospheric stability, and precipitation, vary on diurnal and monthly timescales across the southern-, central-, and northern sub-regions of the GP. It is shown that C and UC GPLLJ events have similar diurnal phasing, but the diurnal amplitude is much greater for UC GPLLJs. C GPLLJs tend to have a faster and more elevated jet nose, less low-level wind shear, and enhanced CAPE and precipitation. UC GPLLJs undergo a larger inertial oscillation (Blackadar mechanism) for all sub-regions, and C GPLLJ have greater geostrophic forcing (Holton mechanism) in the southern and northern GP. The results underscore the need to differentiate between C and UC GPLLJs in future seasonal forecast and climate prediction activities.

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“…More details about the model configuration and physical parameterizations were given in Nikolic et al . (2019). A comparison of the RCM simulation of 2011 LULC with gridded climate analysis (Supporting Information) indicates that the simulation captured reasonably well the observed magnitude and spatial distribution of climate elements across CONUS.…”

Section: Methodsmentioning

confidence: 99%

Will land use land cover change drive atmospheric conditions to become more conducive to wildfires in the United States?

Zhong

Wang

Sciusco

et al. 2021

Intl Journal of Climatology

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The increase in wildfire risk in the United States in recent decades has been linked to rapid growth of the wildland-urban interface and to changing climate. While there have been numerous studies on wildfires and climate change, few have separately assessed the impact of climate response to land-use-land-cover change (LULCC) on wildfires. In this study, we analyse two 10-year regional climate simulations driven by the current (2011) and future (2100) land-use-land-cover patterns to assess modifications by the projected LULCC to the frequency and severity of fire-prone atmospheric conditions described by two fire weather indices, the Canadian Forest Fire Weather Index and the Hot-Dry-Windy Index. The simulation corresponding to future land-use-land-cover pattern yields higher surface temperature and vapour pressure deficit and lower precipitation compared to the simulation with the current pattern in areas where urbanized landscapes replace forests and grasslands, such as along the Piedmont and outside the Chicagoland region, while in areas where croplands replace forests, such as the southeast Coastal Plains, the results are reversed. These changes to local and regional atmospheric conditions lead to longer fire seasons and more extreme fire-weather conditions in much of the eastern United States, specifically in the Southeast and Ohio River Valley where significant urban expansion is projected by the end of the century. Whereas in Southern California where some highly flammable shrublands will be replaced by urban or crop lands, fire-prone atmospheric conditions are likely to be less frequent and less extreme in the future. However, much of California moves towards a yearround fire season under the projected LULCC. The results suggest that by altering atmospheric conditions, LULCC may play an important role in determining fire regime, but the effects are highly heterogeneous and regionalized.

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Sensitivity of Low-Level Jets to Land-Use and Land-Cover Change over the Continental U.S.

Cited by 10 publications

References 35 publications

Quantitative impacts of vertical transport on the long-term trend of nocturnal ozone increase over the Pearl River Delta region during 2006–2019

Quantitative impacts of vertical transport on the long-term trend of nocturnal ozone increase over the Pearl River Delta region during 2006–2019

The Role of Upper-Level Coupling on Great Plains Low-Level Jet Structure and Variability

Will land use land cover change drive atmospheric conditions to become more conducive to wildfires in the United States?

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