The interaction between urbanization and aerosols during a typical winter haze event in Beijing

Abstract. Aerosols cause cooling at the surface by reducing shortwave radiation, while urbanization causes warming by altering the surface albedo and releasing anthropogenic heat. The combined effect of the two phenomena needs to be studied in depth. The effects of urbanization and aerosols were investigated during a typical winter haze event. The event, which occurred in Beijing from 15 to 22 December 2016, was studied via the Rapid-Refresh Multiscale Analysis and Prediction System – Short Term (RMAPS-ST) model. The mechanisms of the impacts of aerosols and urbanization were analyzed and quantified. Aerosols reduced urban-related warming during the daytime by 20 % (from 30 % to 50 %) as concentrations of fine particulate matter (PM2.5) increased from 200 to 400 µg m−3. Conversely, aerosols also enhanced urban-related warming at dawn, and the increment was approximately 28 %, which contributed to haze formation. Urbanization reduced the aerosol-related cooling effect by approximately 54 % during the haze event, and the strength of the impact changed little with increasing aerosol content. The impact of aerosols on urban-related warming was more significant than the impact of urbanization on aerosol-related cooling. Aerosols decreased the urban impact on the mixing-layer height by 148 % and on the sensible heat flux by 156 %. Furthermore, aerosols decreased the latent heat flux; however, this reduction decreased by 48.8 % due to urbanization. The impact of urbanization on the transport of pollutants was more important than that of aerosols. The interaction between urbanization and aerosols may enhance the accumulation of pollution and weigh against diffusion.

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The interaction between urbanization and aerosols during the typical haze event

10.5194/acp-2020-303 ◽

2020 ◽

Author(s):

Miao Yu ◽

Guiqian Tang ◽

Yang Yang ◽

Shiguang Miao ◽

Yizhou Zhang ◽

...

Keyword(s):

Heat Flux ◽

Multiscale Analysis ◽

Sensible Heat Flux ◽

Mixing Layer ◽

Short Term ◽

Haze Event ◽

Mixing Layer Height ◽

Haze Formation ◽

Impact Of Urbanization ◽

The Impact

Abstract. The interaction between aerosols and urbanization during the haze event was investigated using the Rapid-Refresh Multiscale Analysis and Prediction System-Short Term (RMAPS-ST). The mechanisms of the impacts of aerosols and urbanization were also analyzed and quantified. Aerosols reduce urban-related warming during the daytime, and the warming decreased by 30 to 50 % as the concentration of PM2.5 increased from 200 to 400 µg·m−3. Aerosols enhance the urban-related warming at dawn, with an increase of approximately 28 %, which is important for haze formation. Urbanization reduced the aerosol-related cooling effect by approximately 54 % during the haze event, and the strength of the impact changed little with increasing aerosol content. The impact of aerosols on urban-related warming is more significant than the impact of urbanization on aerosol-related cooling. Aerosols decreased the urban-impact on the mixing layer height by 148 % and on the sensible heat flux by 156 %. Furthermore, the aerosols decreased the latent heat flux, and the impact was reduced by 48.8 % by urbanization. The impact of urbanization on the transport of pollutants is more important than that of aerosols. The interaction between urbanization and aerosols may enhance the accumulation of pollution and weigh against diffusion.

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Numerical Evaluation of the Impact of Urbanization on Summertime Precipitation in Osaka, Japan

Advances in Meteorology ◽

10.1155/2015/379361 ◽

2015 ◽

Vol 2015 ◽

pp. 1-11 ◽

Cited By ~ 13

Author(s):

Hikari Shimadera ◽

Akira Kondo ◽

Kundan Lal Shrestha ◽

Ken Kitaoka ◽

Yoshio Inoue

Keyword(s):

Land Use ◽

Heat Flux ◽

Urban Areas ◽

Sensible Heat Flux ◽

Wrf Model ◽

Temporal Distribution ◽

Urban Land Use ◽

Sensible Heat ◽

Impact Of Urbanization ◽

The Impact

This study utilized the Weather Research and Forecasting (WRF) model version 3.5.1 to evaluate the impact of urbanization on summertime precipitation in Osaka, Japan. The evaluation was conducted by comparing the WRF simulations with the present land use and no-urban land use (replacing “Urban” with “Paddy”) for August from 2006 to 2010. The urbanization increased mean air temperature by 2.1°C in urban areas because of increased sensible heat flux and decreased mean humidity by 0.8 g kg−1because of decreased latent heat flux. In addition, the urbanization increased duration of the southwesterly sea breeze. The urbanization increased precipitation in urban areas and decreased in the surrounding areas. The mean precipitation in urban areas was increased by 20 mm month−1(27% of the total amount without the synoptic-scale precipitation). The precipitation increase was generally due to the enhancement of the formation and development of convective clouds by the increase in sensible heat flux during afternoon and evening time periods. The urbanization in Osaka changes spatial and temporal distribution patterns of precipitation and evaporation, and consequently it substantially affects the water cycle in and around the urban areas of Osaka.

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Evaluation of the Surface Urban Energy and Water Balance Scheme (SUEWS) at a Dense Urban Site in Shanghai: Sensitivity to Anthropogenic Heat and Irrigation

Journal of Hydrometeorology ◽

10.1175/jhm-d-18-0057.1 ◽

2018 ◽

Vol 19 (12) ◽

pp. 1983-2005 ◽

Cited By ~ 6

Author(s):

Xiangyu Ao ◽

C. S. B. Grimmond ◽

H. C. Ward ◽

A. M. Gabey ◽

Jianguo Tan ◽

...

Keyword(s):

Heat Flux ◽

Water Balance ◽

Land Surface ◽

Sensible Heat Flux ◽

Anthropogenic Heat ◽

Urban Site ◽

Continuous Irrigation ◽

Anthropogenic Heat Flux ◽

Urban Energy ◽

The Impact

Abstract The Surface Urban Energy and Water Balance Scheme (SUEWS) is used to investigate the impact of anthropogenic heat flux QF and irrigation on surface energy balance partitioning in a central business district of Shanghai. Diurnal profiles of QF are carefully derived based on city-specific hourly electricity consumption data, hourly traffic data, and dynamic population density. The QF is estimated to be largest in summer (mean daily peak 236 W m−2). When QF is omitted, the SUEWS sensible heat flux QH reproduces the observed diurnal pattern generally well, but the magnitude is underestimated compared to observations for all seasons. When QF is included, the QH estimates are improved in spring, summer, and autumn but are poorer in winter, indicating winter QF is overestimated. Inclusion of QF has little influence on the simulated latent heat flux QE but improves the storage heat flux estimates except in winter. Irrigation, both amount and frequency, has a large impact on QE. When irrigation is not considered, the simulated QE is underestimated for all seasons. The mean summer daytime QE is largely overestimated compared to observations under continuous irrigation conditions. Model results are improved when irrigation occurs with a 3-day frequency, especially in summer. Results are consistent with observed monthly outdoor water use. This study highlights the importance of appropriately including QF and irrigation in urban land surface models—terms not generally considered in many previous studies.

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The impact of broadleaved woodland on water resources in lowland UK: II. Evaporation estimates from sensible heat flux measurements over beech woodland and grass on chalk sites in Hampshire

Hydrology and Earth System Sciences ◽

10.5194/hess-9-607-2005 ◽

2005 ◽

Vol 9 (6) ◽

pp. 607-613 ◽

Cited By ~ 12

Author(s):

J. Roberts ◽

P. Rosier ◽

D. M. Smith

Keyword(s):

Heat Flux ◽

Energy Balance ◽

Excellent Agreement ◽

Sensible Heat Flux ◽

Late Summer ◽

Eddy Correlation ◽

Sensible Heat ◽

Flux Measurements ◽

Shallow Soils ◽

The Impact

Abstract. The impact on recharge to the Chalk aquifer of substitution of broadleaved woodland for pasture is a matter of concern in the UK. Hence, measurements of energy balance components were made above beech woodland and above pasture, both growing on shallow soils over chalk in Hampshire. Latent heat flux (evaporation) was calculated as the residual from these measurements of energy balances in which sensible heat flux was measured with an eddy correlation instrument that determined fast response vertical wind speeds and associated temperature changes. Assessment of wind turbulence statistics confirmed that the eddy correlation device performed satisfactorily in both wet and dry conditions. There was excellent agreement between forest transpiration measurements made by eddy correlation and stand level tree transpiration measured with sap flow devices. Over the period of the measurements, from March 1999 to late summer 2000, changes in soil water content were small and grassland evaporation and transpiration estimated from energy balance-eddy flux measurements were in excellent agreement with Penman estimates of potential evaporation. Over the 18-month measurement period, the cumulative difference between broadleaved woodland and grassland was small but evaporation from the grassland was 3% higher than that from the woodland. In the springs of 1999 and 2000, evaporation from the grassland was greater than that from the woodland. However, following leaf emergence in the woodland, the difference in cumulative evaporation diminished until the following spring.

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Seasonal Surface Air Temperature and Precipitation in the FSU Climate Model Coupled to the CLM2

Journal of Climate ◽

10.1175/jcli3470.1 ◽

2005 ◽

Vol 18 (16) ◽

pp. 3217-3228 ◽

Cited By ~ 16

Author(s):

D. W. Shin ◽

S. Cocke ◽

T. E. LaRow ◽

James J. O’Brien

Keyword(s):

Heat Flux ◽

Air Temperature ◽

Climate Model ◽

Initial Conditions ◽

Sensible Heat Flux ◽

Surface Air Temperature ◽

Community Land Model ◽

Temperature And Precipitation ◽

The Impact ◽

Convective Scheme

Abstract The current Florida State University (FSU) climate model is upgraded by coupling the National Center for Atmospheric Research (NCAR) Community Land Model Version 2 (CLM2) as its land component in order to make a better simulation of surface air temperature and precipitation on the seasonal time scale, which is important for crop model application. Climatological and seasonal simulations with the FSU climate model coupled to the CLM2 (hereafter FSUCLM) are compared to those of the control (the FSU model with the original simple land surface treatment). The current version of the FSU model is known to have a cold bias in the temperature field and a wet bias in precipitation. The implementation of FSUCLM has reduced or eliminated this bias due to reduced latent heat flux and increased sensible heat flux. The role of the land model in seasonal simulations is shown to be more important during summertime than wintertime. An additional experiment that assimilates atmospheric forcings produces improved land-model initial conditions, which in turn reduces the biases further. The impact of various deep convective parameterizations is examined as well to further assess model performance. The land scheme plays a more important role than the convective scheme in simulations of surface air temperature. However, each convective scheme shows its own advantage over different geophysical locations in precipitation simulations.

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Evaluation of Noah-MP Land-Model Uncertainties over Sparsely Vegetated Sites on the Tibet Plateau

Atmosphere ◽

10.3390/atmos11050458 ◽

2020 ◽

Vol 11 (5) ◽

pp. 458

Author(s):

Guo Zhang ◽

Fei Chen ◽

Yueli Chen ◽

Jianduo Li ◽

Xindong Peng

Keyword(s):

Heat Flux ◽

Organic Matter ◽

Soil Organic Matter ◽

Tibetan Plateau ◽

Sensible Heat Flux ◽

Limiting Factors ◽

Tibet Plateau ◽

The Tibetan Plateau ◽

Annual Total ◽

The Impact

The water budget and energy exchange over the Tibetan Plateau (TP) region play an important role on the Asian monsoon. However, it is not well presented in the current land surface models (LSMs). In this study, uncertainties in the Noah with multiparameterization (Noah-MP) LSM are assessed through physics ensemble simulations in three sparsely vegetated sites located in the central TP. The impact of soil organic matter on energy flux and water cycles, along with the influence of uncertainties in precipitation are explored using observations at those sites during the third Tibetan Plateau Experiment from 1August2014 to31July2015. The greatest uncertainties are in the subprocesses of the canopy resistance, soil moisture limiting factors for evaporation, runoff (RNF) and ground water, and surface-layer parameterization. These uncertain subprocesses do not change across the different precipitation datasets. More precipitation can increase the annual total net radiation (Rn), latent heat flux (LH) and RNF, but decrease sensible heat flux (SH). Soil organic matter enlarges the annual total LH by ~26% but lessens the annual total Rn, SH, and RNF by ~7%, 7%, and 39%, respectively. Its effect on the LH and RNF at the Nagqu site, which has a sand soil texture type, is greater than that at the other two sites with sandy loam. This study highlights the importance of precipitation uncertainties and the effect of soil organic matter on the Noah-MP land-model simulations. It provides a guidance to improve the Noah-MP LSM further and hence the land-atmosphere interactions simulated by weather and climate models over the TP region.

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A Test Study of an Energy and Mass Balance Model Application to a Site on Urumqi Glacier No. 1, Chinese Tian Shan

Water ◽

10.3390/w12102865 ◽

2020 ◽

Vol 12 (10) ◽

pp. 2865

Author(s):

Puyu Wang ◽

Zhongqin Li ◽

Christoph Schneider ◽

Hongliang Li ◽

Alexandra Hamm ◽

...

Keyword(s):

Heat Flux ◽

Mass Balance ◽

Sensible Heat Flux ◽

Shortwave Radiation ◽

Balance Model ◽

Mass Balance Model ◽

Sensitivity Testing ◽

Glacier Surface ◽

Precipitation Decrease ◽

Tian Shan

In this study, energy and mass balance is quantified using an energy balance model to represent the glacier melt of Urumqi Glacier No. 1, Chinese Tian Shan. Based on data from an Automatic Weather Station (4025 m a.s.l) and the mass balance field survey data nearby on the East Branch of the glacier, the “COupled Snowpack and Ice surface energy and Mass balance model” (COSIMA) was used to derive energy and mass balance simulations during the ablation season of 2018. Results show that the modeled cumulative mass balance (−0.67 ± 0.03 m w.e.) agrees well with the in-situ measurements (−0.64 ± 0.16 m w.e.) (r2 = 0.96) with the relative difference within 5% during the study period. The correlation coefficient between modeled and observed surface temperatures is 0.88 for daily means. The main source of melt energy at the glacier surface is net shortwave radiation (84%) and sensible heat flux (16%). The energy expenditures are from net longwave radiation (55%), heat flux for snow/ice melting (32%), latent heat flux of sublimation and evaporation (7%), and subsurface heat flux (6%). The sensitivity testing of mass balance shows that mass balance is more sensitive to temperature increase and precipitation decrease than temperature decrease and precipitation increase.

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Urban signals in high-resolution weather and climate simulations: role of urban land-surface characterisation

Theoretical and Applied Climatology ◽

10.1007/s00704-020-03294-1 ◽

2020 ◽

Vol 142 (1-2) ◽

pp. 701-728

Author(s):

Denise Hertwig ◽

Sue Grimmond ◽

Margaret A. Hendry ◽

Beth Saunders ◽

Zhengda Wang ◽

...

Keyword(s):

Heat Flux ◽

Land Cover ◽

Sensible Heat Flux ◽

Urban Land ◽

Heat Fluxes ◽

Anthropogenic Heat ◽

Urban Surface ◽

City Centre ◽

Sensible Heat ◽

Climate Simulations

Abstract Two urban schemes within the Joint UK Land Environment Simulator (JULES) are evaluated offline against multi-year flux observations in the densely built-up city centre of London and in suburban Swindon (UK): (i) the 1-tile slab model, used in climate simulations; (ii) the 2-tile canopy model MORUSES (Met Office–Reading Urban Surface Exchange Scheme), used for numerical weather prediction over the UK. Offline, both models perform better at the suburban site, where differences between the urban schemes are less pronounced due to larger vegetation fractions. At both sites, the outgoing short- and longwave radiation is more accurately represented than the turbulent heat fluxes. The seasonal variations of model skill are large in London, where the sensible heat flux in autumn and winter is strongly under-predicted if the large city centre magnitudes of anthropogenic heat emissions are not represented. The delayed timing of the sensible heat flux in the 1-tile model in London results in large negative bias in the morning. The partitioning of the urban surface into canyon and roof in MORUSES improves this as the roof tile is modelled with a very low thermal inertia, but phase and amplitude of the grid box-averaged flux critically depend on accurate knowledge of the plan-area fractions of streets and buildings. Not representing non-urban land cover (e.g. vegetation, inland water) in London results in severely under-predicted latent heat fluxes. Control runs demonstrate that the skill of both models can be greatly improved by providing accurate land cover and morphology information and using representative anthropogenic heat emissions, which is essential if the model output is intended to inform integrated urban services.

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Parameterization of Urban Sensible Heat Flux from Remotely Sensed Surface Temperature: Effects of Surface Structure

Remote Sensing ◽

10.3390/rs11111347 ◽

2019 ◽

Vol 11 (11) ◽

pp. 1347 ◽

Cited By ~ 2

Author(s):

Jinxin Yang ◽

Massimo Menenti ◽

E. Scott Krayenhoff ◽

Zhifeng Wu ◽

Qian Shi ◽

...

Keyword(s):

Heat Flux ◽

Surface Temperature ◽

Sensible Heat Flux ◽

Effective Resistance ◽

Three Dimensions ◽

Sensible Heat ◽

Wall Surface ◽

Surface Temperatures ◽

Flux Parameterization ◽

The Impact

Sensible heat exchange has important consequences for urban meteorology and related applications. Directional radiometric surface temperatures of urban canopies observed by remote sensing platforms have the potential to inform estimations of urban sensible heat flux. An imaging radiometer viewing the surface from nadir cannot capture the complete urban surface temperature, which is defined as the mean surface temperature over all urban facets in three dimensions, which includes building wall surface temperatures and requires an estimation of urban sensible heat flux. In this study, a numerical microclimate model, Temperatures of Urban Facets in 3-D (TUF-3D), was used to model sensible heat flux as well as radiometric and complete surface temperatures. Model data were applied to parameterize an effective resistance for the calculation of urban sensible heat flux from the radiometric (nadir view) surface temperature. The results showed that sensible heat flux was overestimated during daytime when the radiometric surface temperature was used without the effective resistance that accounts for the impact of wall surface temperature on heat flux. Parameterization of this additional resistance enabled reasonably accurate estimates of urban sensible heat flux from the radiometric surface temperature.

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Analysis of a 3 year meteorological record from the ablation zone of Morteratschgletscher, Switzerland: energy and mass balance

Journal of Glaciology ◽

10.3189/172756500781832657 ◽

2000 ◽

Vol 46 (155) ◽

pp. 571-579 ◽

Cited By ~ 66

Author(s):

J. Oerlemans

Keyword(s):

Heat Flux ◽

Sensible Heat Flux ◽

Longwave Radiation ◽

Solar Radiation Pressure ◽

Turbulent Energy ◽

Snow Accumulation ◽

Shortwave Radiation ◽

Glacier Surface ◽

The Mean ◽

Snow Temperature

AbstractSince 1 October 1995, an automatic weather station has been operated on the tongue of Morteratschgletscher, Switzerland. The station stands freely on the ice, and sinks with the melting glacier surface. It is located at 2100 m a.s.l., and measures air temperature, wind speed and direction, incoming and reflected solar radiation, pressure and snow temperature. A sonic ranger, mounted to stakes drilled into the ice, measures surface height from which melt rates and snow accumulation can be derived. In this paper the data for the period 1 October 1995 to 30 September 1998 are used to evaluate the surface energy balance. The turbulent energy fluxes are calculated with the bulk method. The turbulent exchange coefficient Ch is used as a control parameter. With Ch = 0.00127 the calculated melt equals the observed melt, which is 17.70 m w.e. over the 3 years. When averaged over the time when melting occurs (i.e. 35% of the time), the mean surface heat flux equals 191 W m−2. Net shortwave radiation contributes 177 W m−2, net longwave radiation −25 W m−2, the sensible-heat flux 31 W m−2 and the latent-heat flux 8 W m−2.

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