Michael Manyin

The Impact of Urbanization on Current and Future Coastal Precipitation: A Case Study for Houston

The approach of this study was to determine, theoretically, what impact current and future urban land use in the coastal city of Houston, Texas has on the space and time evolution of precipitation on a ‘typical’ summer day. Regional model simulations of a case study for 25 July 2001 were applied to investigate possible effects of urban land cover on precipitation development. Simulations in which Houston urban land cover was included resolved rain cells associated with the sea breeze front and a possible urban circulation on the northwest fringe of the city. Simulations without urban land cover did not capture the initiation and full intensity of the ‘hypothesized’ urban-induced rain cell. The response is given the terminology the ‘urban rainfall effect’ or URE. An urban growth model (UrbanSim) was used to project the urban land-cover growth of Houston, Texas from 1992 to 2025. A regional atmospheric-land surface model was then run with the 2025 urban land-cover scenario. Though we used a somewhat theoretical treatment, our results show the sensitivity of the atmosphere to urban land cover and illustrate how atmosphere — land interactions can affect cloud and precipitation processes. Two urban-induced features, convergence zones along the inner fringe of the city and an urban low-pressure perturbation, appear to be important factors that lead to enhanced rain clouds independently or in conjunction with the sea breeze. Simulations without the city (NOURBAN) produced less cumulative rainfall in the west-northwest Houston area than simulations with the city represented (URBAN). Future urban land-cover growth projected by UrbanSim (URBAN2025) led to a more expansive area of rainfall, owing to the extended urban boundary and increased secondary outflow activity. This suggests that the future urban land cover might lead to temporal and spatial precipitation variability in coastal urban microclimates. It was beyond the scope of the analysis to conduct an extensive sensitivity analysis of cause — effect relationships, though the experiments provide some clues as to why the rainfall evolution differs. This research demonstrates a novel application of urban planning and weather — climate models. It also raises viable questions concerning future planning strategies in urban environments in consideration of hydroclimate changes.

The effect of representing bromine from VSLS on the simulation and evolution of Antarctic ozone

We use the Goddard Earth Observing System Chemistry-Climate Model (GEOSCCM), a contributor to both the 2010 and 2014 WMO Ozone Assessment Reports, to show that inclusion of 5 parts per trillion (ppt) of stratospheric bromine (Bry) from very short-lived substances (VSLS) is responsible for about a decade delay in ozone hole recovery. These results partially explain the significantly later recovery of Antarctic ozone noted in the 2014 report, as bromine from VSLS was not included in the 2010 Assessment. We show multiple lines of evidence that simulations that account for VSLS Bry are in better agreement with both total column BrO and the seasonal evolution of Antarctic ozone reported by the Ozone Monitoring Instrument (OMI) on NASAs Aura satellite. In addition, the near zero ozone levels observed in the deep Antarctic lower stratospheric polar vortex are only reproduced in a simulation that includes this Bry source from VSLS.

Urban Induced Rainfall Modifications on Urban Hydrologic Response

Potential effects of urban areas on rainfall patterns have been increasingly studied, debated and recorded in the archived literature since 1921, when Horton o…

Modeling Urban Effects on the Precipitation Component of the Water Cycle

Precipitation is an important component of the global water cycle and a proxy for changing climate. Proper understanding and quantification of spatio-temporal precipitation variability is critical for a range of meteorological, hydrological, and climate processes. Past and current literature has presented theories and observational studies on how urbanization affects precipitation. Assessment of the urban environment’s (land use, aerosols, thermal properties) impact on precipitation will be increasingly important in ongoing climate diagnostics and prediction, global water and energy cycle (GWEC) analysis and modeling, weather forecasting, freshwater resource management, urban planning-design, and land-atmosphere-ocean interface processes. This chapter presents a review of findings and methods related to “urban rainfall effect” studies with an emphasis on numerical modeling strategies. Numerical modeling of atmosphere-land interactions enables controlled experimentation to address fundamental research questions.

Chemical Mechanisms and Their Applications in the Goddard Earth Observing System (GEOS) Earth System Model

Abstract NASAs Goddard Earth Observing System (GEOS) Earth System Model (ESM) is a modular, general circulation model (GCM), and data assimilation system (DAS) that is used to simulate and study the coupled dynamics, physics, chemistry, and biology of our planet. GEOS is developed by the Global Modeling and Assimilation Office (GMAO) at NASA Goddard Space Flight Center. It generates near‐real‐time analyzed data products, reanalyses, and weather and seasonal forecasts to support research targeted to understanding interactions among Earth System processes. For chemistry, our efforts are focused on ozone and its influence on the state of the atmosphere and oceans, and on trace gas data assimilation and global forecasting at mesoscale discretization. Several chemistry and aerosol modules are coupled to the GCM, which enables GEOS to address topics pertinent to NASAs Earth Science Mission. This paper describes the atmospheric chemistry components of GEOS and provides an overview of its Earth System Modeling Framework (ESMF)‐based software infrastructure, which promotes a rich spectrum of feedbacks that influence circulation and climate, and impact human and ecosystem health. We detail how GEOS allows model users to select chemical mechanisms and emission scenarios at run time, establish the extent to which the aerosol and chemical components communicate, and decide whether either or both influence the radiative transfer calculations. A variety of resolutions facilitates research on spatial and temporal scales relevant to problems ranging from hourly changes in air quality to trace gas trends in a changing climate. Samples of recent GEOS chemistry applications are provided.

A Model and Satellite-Based Analysis of the Tropospheric Ozone Distribution in Clear versus Convectively Cloudy Conditions

Satellite observations of in-cloud ozone concentrations from the OMI and MLS instruments show substantial differences from background ozone concentrations. We develop a method for comparing a free-running chemistry-climate model (CCM) to in-cloud and background ozone observations using a simple criterion based on cloud fraction to separate cloudy and clear-sky days. We demonstrate that the CCM simulates key features of the in-cloud versus background ozone differences and of the geographic distribution of in-cloud ozone. Since the agreement is not dependent on matching the meteorological conditions of a specific day, this is a promising method for diagnosing how accurately CCMs represent the relationships between ozone and clouds, including the lower ozone concentrations shown by in-cloud satellite observations. Since clouds are associated with convection as well as changes in chemistry, we diagnose the tendency of tropical ozone at 400 hPa due to chemistry, convection and turbulence, and large-scale dynamics. While convection acts to reduce ozone concentrations at 400 hPa throughout much of the tropics, it has the opposite effect over highly polluted regions of South and East Asia.

The effect of urbanization-induced rainfall variability on hydrologic response: Linking mesoscale meteorological model output to an urban watershed model

This paper reports the preliminary results of a study of the relative effect of urban-induced precipitation variability on the hydrological response of a large urban watershed. The study involves (1) developing a mesoscale meteorological model centered on the Houston metropolitan area to simulate urban effects on meteorological fields, particularly precipitation, (2) developing a stormwater runoff model for a large urban watershed in the Houston metropolitan area, and (3) using the simulated rainfall fields as input to the watershed model. Meteorological simulations were performed to elicit the urban effect on a case study precipitation event and the simulated rainfall fields are being used as input to the stormwater runoff model to study the differences in runoff response caused by the urban rainfall modification. This paper describes the development and verification of the models and outlines the concept of the use of the simulated rainfall fields as input to the runoff model. Results of the linkage and analysis of urban rainfall modification effect on runoff response will be presented at the conference. Background There have been several recent efforts to link mesoscale meteorological models with hydrologic models. The objectives have typically been to provide improved representation of the spatial variability of precipitation for input to hydrologic models to improve the prediction of flood magnitudes and extent and to increase the forecasting lead-time. Thielen and Creutin (1997) conducted a runoff analysis using a coupled meteorological-hydrologic model where the simulated rainfall fields served as input to the hydrologic model. In their study, TRAPPES Radiosonde data were used as input to the Clark Module meteorological model. The Clark Module uses two way interactive grid nesting, which provides the ability to use multiple resolution grid domains. Horizontal grids consisted of 9, 3, 1 and 0.5 km resolutions. The vertical resolutions of the first three grids were 250 meters and 125 meters for the finest horizontal resolution. The urban watershed area studied is located near Paris and has an approximate area of 116 km 2 . Land surface and hydraulic systems for the study area were analyzed using the CAREDAS (Calcul des Reseaux d’Assainissement) model. The CAREDAS modeling application uses two modules to estimate urban stormwater runoff. The PLUTON module uses a lumped approach to calculate rainfall-runoff transformations for subbasins. PLUTON