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EPJ Web Conf., Volume 237, 2020 The 29th International Laser Radar Conference (ILRC 29), This study focuses on the distribution of ozone (O₃) concentration near the Chesapeake Bay, USA (hereafter CB) by integrating observations and model simulations. The motivation of this work is to understand reasons causing the horizontal and vertical distribution of pollutants (mainly O₃) near the CB. The O₃ exceedance over the CB happens very frequently during summer and the Maryland Department of Environment intends to find out the reasons in order to make policy-related decision. The observation data used in this study are from the Ozone Water-Land Environmental Transition Study-2 (OWLETS-2) field campaign, including observations from O₃ lidar, Doppler wind lidar, ozonesonde. The mesoscale model employed is Weather Research and Forecasting model coupled with chemistry (WRF-Chem) version 3.9.1. The anthropogenic emission dataset is from National Emission Inventory 2011 (NEI-2011), including various emission species, e.g., CO, NOₓ, SO₂, NH₃, PM₂.₅, PM₁₀, etc. The meteorological initial and boundary conditions are from the Northern American Regional Reanalysis (NARR) dataset, which is a high-resolution combined model and assimilated dataset from the National Centers for Environmental Prediction (NCEP). There are several findings of this study based on the model simulations and ground-based observations. Actually, at the beginning of study, we considered two different versions of anthropogenic emissions from NEI-2005 and NEI-2011 developed by the Environment Protection Agency (EPA). EPA added the anthropogenic emissions over CB from boats and ships while updating from NEI-2005 to NEI-2011. For model performance evaluation, we employed AirNow surface hourly O₃ mixing ratio diurnal variation and compared it with model simulations. For instance, at Essex site near Baltimore City, observed O₃ has a strong diurnal variation, with minimum (25 ppbv) just after sunrise (05:00 EST), and with maximum (75 ppbv) around afternoon (15:00 EST). Even the model simulation has a good agreement with the observation, it underestimates the mean O₃ mixing ratio by about 15-20 ppbv. Both the surface and 700 mb level horizontal spatial distribution of O₃ indicate the higher O₃ concentration over the north-middle CB, with surface O₃ mixing ratio of 40-50 ppbv and 700 mb level O₃ mixing ratio of 60 ppbv, which means the surface O₃ was lifted up after production. The vertical profiles of wind of both model and Doppler wind lidar match very well, indicating that the model captured the vertical variation of wind. However, the vertical profiles of O₃ from model simulation, ozonesonde, and O₃ lidar suggests that model simulation underestimated the O₃ from surface to 4.5 km. In addition, the model simulation captured the vertical mixing of O₃ from surface to 2 km, while misses the O₃ variation above 2 km. In order to study the influence of bay breeze on the O₃ small scale transport, three vertical cross sections through the CB from west to east at the northern, middle, and southern CB. The results show that higher O₃ concentration above the CB. The bay breeze over the southern CB is stronger than the northern CB. The planetary boundary layer height over the CB is dramatically lower than the surrounding land in the day, which contributes to the surface higher O₃ concentration over the CB.

Water vapor advection is an important diagnostic parameter for initiation and sustenance of convective systems. This variable has traditionally been explored with balloon soundings or models, but lidar provides a unique opportunity to continuously resolve spatial and temporal evolution of water vapor transport with relatively high resolution. In this study we utilize co-located Doppler wind lidars and water vapor lidars (DIAL and Raman) at multiple sites to investigate water vapor advection. A case of nocturnal convection in the Great Plains is analyzed with these observations and compared to the North American Mesoscale Forecast System (NAM) operational forecast model.

The 28th International Laser Radar Conference (ILRC 28), Rain evaporation significantly contributes to moisture and heat cloud budgets. In this paper, we illustrate an approach to estimate the median volume raindrop diameter and the rain evaporation rate profiles from dual-wavelength lidar measurements. These observational results are compared with those provided by a model analytical solution. We made use of measurements from the multi-wavelength Raman lidar BASIL.

The National Weather Service (NWS) is investigating the potential of utilizing the Automatic Surface Observing System’s (ASOS) cloud base height indicator, the Vaisala CL31 ceilometer, to profile aerosols in the atmosphere. Field test sites of stand-alone CL31 ceilometers have been established, primarily, around the Washington DC metropolitan area, with additional systems in southwest USA and Puerto Rico. The CL31 PBL project examines the CL31 data collected for data quality, mixing height retrieval applicability, and its compliment to satellite data. This paper reviews the topics of the CL31 data quality and mixing height retrieval applicability.

The 28th International Laser Radar Conference (ILRC 28), Results from the PECAN (Plains Elevated Convection at Night) campaign are discussed. In particular, the utility of simple backscatter lidars/ceilometers in quantifying atmospheric dynamics parameters and variables as well as evolution of the lower tropospheric dynamics are made. Cases of bore wave dynamics and the potential of these events in lofting of low level, moist, airmass and its consequence in thunderstorm initiation are made. A suite of thermodynamic profiling instruments are combined and compared to describe and visualize lower tropospheric dynamic evolution.

The 28th International Laser Radar Conference (ILRC 28), A low-level jet (LLJ) is a prominent wind speed peak in the lower troposphere. Nocturnal LLJs have been shown to transport and mix atmospheric constituents from the residual layer down to the surface, breaching quiescent nocturnal conditions due to high wind shear. A new fuzzy logic algorithm combining turbulence and aerosol information from Doppler lidar scans can resolve the strength and depth of this mixing below the jet. Conclusions will be drawn about LLJ relations to turbulence and mixing.