Variations Of Planetary Boundary Layer Height Research Articles

The Effect of Surface Heating Heterogeneity on Boundary Layer Height and Its Dependence on Background Wind Speed

AbstractThe planetary boundary layer height (PBLH) is a fundamental variable of the planetary boundary layer (PBL). The effect of surface heterogeneity is challenging in the PBL parameterization for numerical weather and climate models. Here we use large eddy simulation data to investigate the impact of surface heating heterogeneity on the PBLH spatial variations and mean values over a domain of typical mesoscale model grid size. It is found that this impact depends on background wind condition. Variance decomposition and Fourier spectra both reveal that for the fully developed sheared convective PBL, surface heterogeneity contributes little to the spatial variation of PBLH, except for the case with heterogeneity scale of 14.4 km. This suggests that surface heterogeneity with length scales less than ∼10 km, which is typical for mesoscale modeling, does not induce significant subgrid spatial variation of PBLH. The domain‐averaged PBLH is found to generally increase as surface heterogeneity scale decreases, until reaching the scale on the order of PBLH. The findings can be used to inform the parameterization development of PBL processes over heterogeneous surface.

Diurnal Variation of the Planetary Boundary Layer Height Observed from GNSS Radio Occultation and Radiosonde Soundings over the Southern Great Plains

Abstract The planetary boundary layer (PBL) height (PBLH) is a key physical parameter of the PBL affected by numerous physical processes within the boundary layer. Specifically, the PBLH over land exhibits large spatial and temporal variation across different geographical regions. In this study, the Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC) radio occultation (RO) profiles and high-resolution radiosonde profiles from 2007 to 2013 were analyzed to estimate the diurnal cycle of the PBLH over the Southern Great Plains (SGP) in the United States. Large variations in PBLH derived from radiosonde temperature, moisture, and refractivity are observed on seasonal scales. COSMIC RO is capable of observing diurnal and seasonal variations in the terrestrial PBLH over the SGP region. Annual mean diurnal amplitude of approximately 250 m in the terrestrial PBLH was observed, with maxima occurring at around 1500 local solar time (LST) in both the collocated radiosondes and COSMIC RO profiles. Seasonal changes in the PBLH diurnal cycles ranging from approximately 100 to 400 m were also observed. Such PBL diurnal and seasonal changes can be further incorporated into PBL parameterizations to help improve weather and climate model prediction. Significance Statement The atmospheric planetary boundary layer (PBL) and its height (PBLH) control many atmospheric processes that affect our everyday lives. Observations of the PBL are usually limited to radiosondes at limited time intervals. GNSS radio occultation (RO) provide high-vertical-resolution atmospheric observations that are ideal for PBL study. This study demonstrates that the GNSS RO is capable of capturing the diurnal and seasonal variations of the PBLH over the southern Great Plains (SGP) well as compared to the collocated radiosonde observations.

Examining the characteristics of planetary boundary layer height and its relationship with atmospheric parameters over Indian sub-continent

Planetary boundary layer plays a critical role in the monsoon circulation studies at regional scales through exchange of land surface fluxes (heat and moisture) with atmosphere. The objective of the present study is to identify the spatial variability of long-term seasonal trends of planetary boundary layer height (PBLH) over Indian subcontinent and its association with atmospheri parameters. Monthly atmospheric boundary layer height data obtained from European centre for medium range weather forecast ERA-5 reanalysis has been used for the study during 1980–2018. Statistically robust non-parametric Mann Kendall test is used to investigate the significance of trend at 95% confidence interval. From the results it has been observed that decreasing trend for PBLH is noticed during pre-monsoon and monsoon seasons over Indian region. PBLH over central and north-west India is deeper (1600–1800 m) during pre-monsoon season whereas PBLH is shallow during other seasons. Seasonal variation of PBLH shows a strong negative association with the relative humidity (r more than −0.8) whereas it shows strong positive association with surface temperature (r > 0.7) and surface zonal winds (r > 0.5) over Indian subcontinent. Evaporative fraction which acts as a dominant controlling factor for the variation in PBLH is positively associated (r > 0.7) with the PBLH during monsoon season. Decreasing trend of PBLH during monsoon season may be attributed to the decrease in latent heat flux and increase in relative humidity that results in entrap of moisture at lower levels and may enhance the formation of extreme events. Inter annual variability of PBLH over Indian subcontinent demonstrates in-phase relationship with the deficit and excess monsoon years. Further to this, PBLH is found to be strongly negatively correlated with PM2.5 (r more than −0.5) during pre-monsoon and monsoon seasons suggesting an opposite phase relationship between the two parameters.

Simulated Atmospheric Response to Four Projected Land-Use Land-Cover Change Scenarios for 2050 in the North-Central United States

AbstractLand-use land-cover change (LULCC) has become an important topic of research for the central United States because of the extensive conversion of the natural prairie into agricultural land, especially in the northern Great Plains. As a result, shifts in the natural climate (minimum/maximum temperature, precipitation, etc.) across the north-central United States have been observed, as noted within the Fourth National Climate Assessment (NCA4) report. Thus, it is necessary to understand how further LULCC will affect the near-surface atmosphere, the lower troposphere, and the planetary boundary layer (PBL) atmosphere over this region. The goal of this work was to investigate the utility of a new future land-use land-cover (LULC) dataset within the Weather Research and Forecasting (WRF) modeling system. The present study utilizes a modeled future land-use dataset developed by the Forecasting Scenarios of Land-Use Change (FORE-SCE) model to investigate the influence of future (2050) land use on a simulated PBL development within the WRF Model. Three primary areas of LULCC were identified within the FORE-SCE future LULC dataset across Nebraska and South Dakota. Variations in LULC between the 2005 LULC control simulation and four FORE-SCE simulations affected near-surface temperature (0.5°–1°C) and specific humidity (0.3–0.5 g kg−1). The differences noted in the temperature and moisture fields affected the development of the simulated PBL, leading to variations in PBL height and convective available potential energy. Overall, utilizing the FORE-SCE dataset within WRF produced notable differences relative to the control simulation over areas of LULCC represented in the FORE-SCE dataset.

Estimation of planetary boundary layer height using Suomi NPP-CrIS soundings

ABSTRACTThe study estimates planetary boundary layer height (PBLH) using temperature and humidity profiles from Cross-Track Infrared Sounder (CrIS) onboard Suomi National Polar-Orbiting Operational Environmental Satellite System Preparatory Project (SNPP). PBLH is estimated using six different methods and also using an integrated approach. PBLH estimated from SNNP-CrIS soundings by the integrated approach is compared with the PBLH values estimated using atmospheric profiles from radiosonde ascents and Constellation Observing System for Meteorology Ionosphere and Climate-radio occultation (COSMIC-RO) measurements. Analysis shows reasonable agreement of PBLH values from SNPP-CrIS soundings with those from radiosonde measurements and COSMIC-RO retrievals, thus revealing the capability of atmospheric profiles from SNNP-CrIS for the characterization of planetary boundary layer (PBL) with excellent spatial resolution and coverage. PBLH from SNNP-CrIS soundings are observed to be overestimated by around 336 m compared to the estimates from radiosonde ascends and is partly attributed to the difference in time of observations and coarse vertical resolution of the SNPP-CrIS-derived profiles. Compared to the estimates from SNPP-CrIS soundings, PBLH values from COSMIC-RO profiles are overestimated by around 596 m. Estimates from SNPP-CrIS soundings, through the integrated approach, are further used to examine the spatial and seasonal variations of PBLH over the Indian landmass. PBLH is observed highest in pre-monsoon and lowest in winter over most of the regions. Due to rainfall and associated changes in lower atmosphere and surface characteristics, PBLH is observed shallow during monsoon.

Spatial and Temporal Variation in PBL Height over the Korean Peninsula in the KMA Operational Regional Model

Spatial and temporal variations in planetary boundary layer height (PBLH) over the Korean Peninsula and its surrounding oceans are investigated using a regional grid model operated at the Korea Meteorological Administration (KMA). Special attention is placed on daily maximum mixing height for evaluation against two radiosonde observation datasets. In order to construct a new high-resolution PBLH database with 3-hour time and 10 km spatial resolution, short-term integrations with the regional model are carried out for a one-year period from June 2010 to May 2011. The resulting dataset is then utilized to explore the seasonal patterns of horizontal PBLH distribution over the peninsula for one year. Frequency distributions as well as monthly and diurnal variations of PBLH at two selected locations are examined. This study reveals specific spatiotemporal structure of boundary layer depth over the Korean Peninsula for the first time at a relatively high-resolution scale. The results are expected to provide insights into the direction for operational tuning and future development in the model boundary layer schemes at KMA.