Parameterization of clear sky effective emissivity under surface-based temperature inversion at Dome C and South Pole, Antarctica

2013 ◽  
Vol 25 (5) ◽  
pp. 697-710 ◽  
Author(s):  
Maurizio Busetto ◽  
Christian Lanconelli ◽  
Mauro Mazzola ◽  
Angelo Lupi ◽  
Boyan Petkov ◽  
...  
Keyword(s):  
Inversion Layer ◽  
Lower Troposphere ◽  
Longwave Radiation ◽  
Ground Level ◽  
Temperature Inversion ◽  
Maximum Temperature ◽  
South Pole ◽  
Effective Emissivity ◽  
Clear Sky ◽  
Good Proxy

AbstractFor most parts of the year the Antarctic Plateau has a surface temperature inversion with strength c. 20 K. Under such conditions the warmer air at the top of the inversion layer contributes more to the clear sky atmospheric longwave radiation at surface level than does the colder air near the ground. Hence, it is more appropriate to relate longwave irradiance (LWI) to the top of the inversion layer temperature (Tm) than to the ground level temperature (Tg). Analysis of radio soundings carried out at Dome C and South Pole during 2006–08 shows that the temperature at 400 m above the surface (T400) is a good proxy for Tm and is linearly related to Tg with correlation coefficients greater than 0.8. During summer, radiosonde measurements show almost isothermal conditions, hence T400 still remains a good proxy for the lower troposphere maximum temperature. A methodology is presented to parameterize the clear sky effective emissivity in terms of the troposphere maximum temperature, using ground temperature measurements. The predicted LWI values for both sites are comparable with those obtained using radiative transfer models, while for Dome C the bias of 0.8 W m-2 and the root mean square (RMS) of 6.2 W m-2 are lower than those calculated with previously published parametric equations.

scholarly journals Methodology for determining multilayered temperature inversions

2015 ◽  
Vol 8 (5) ◽  
pp. 2051-2060 ◽  
Author(s):  
G. J. Fochesatto
Keyword(s):  
Temperature Profile ◽  
Large Scale ◽  
Error Function ◽  
Inversion Layer ◽  
Lower Troposphere ◽  
Temperature Inversion ◽  
Linear Interpolation ◽  
Pollution Dispersion ◽  
Thermal Inversion ◽  
Temperature Inversions

Abstract. Temperature sounding of the atmospheric boundary layer (ABL) and lower troposphere exhibits multilayered temperature inversions specially in high latitudes during extreme winters. These temperature inversion layers are originated based on the combined forcing of local- and large-scale synoptic meteorology. At the local scale, the thermal inversion layer forms near the surface and plays a central role in controlling the surface radiative cooling and air pollution dispersion; however, depending upon the large-scale synoptic meteorological forcing, an upper level thermal inversion can also exist topping the local ABL. In this article a numerical methodology is reported to determine thermal inversion layers present in a given temperature profile and deduce some of their thermodynamic properties. The algorithm extracts from the temperature profile the most important temperature variations defining thermal inversion layers. This is accomplished by a linear interpolation function of variable length that minimizes an error function. The algorithm functionality is demonstrated on actual radiosonde profiles to deduce the multilayered temperature inversion structure with an error fraction set independently.

scholarly journals The Innovative Method of Purifying Polluted Air in the Region of an Inversion Layer

2021 ◽  
Vol 9 ◽  
Author(s):  
F. Jędrzejek ◽  
D. Gryboś ◽  
J. Zyśk ◽  
J. Leszczyński ◽  
K. Szarłowicz ◽  
...  
Keyword(s):  
Air Pollution ◽  
Natural Convection ◽  
Shock Waves ◽  
Inversion Layer ◽  
Ground Level ◽  
Temperature Inversion ◽  
Vertical Movement ◽  
Vertical Movements ◽  
Innovative Method ◽  
High Concentrations

Formation of the inversion layer causes a lack of vertical movement of the atmosphere and the occurrence of long-lasting high concentrations of pollution. The new invention makes use of shock waves, created by explosions of a mixture of flammable gases and air. These shock waves destroy the structure of the temperature inversion layer in the atmosphere and restore natural convection. Restoring vertical movements within the atmosphere causes a reduction in air pollution at the ground level. The system was tested at full technical scale in the environment. Preliminary effects indicate an average 24% reduction in PM10 concentration in the smog layer at ground level up to 20 m, with the device operating in 11-min series consisting of 66 explosions. It was also shown that the device is able to affect a larger area, at least 4 km2.

scholarly journals Radiosonde-Observed Vertical Profiles and Increasing Trends of Temperature and Humidity during 2005–2018 at the South Pole

Atmosphere ◽  
2019 ◽  
Vol 10 (7) ◽  
pp. 365 ◽  
Author(s):  
Min Xu ◽  
Yubin Li ◽  
Qinghua Yang ◽  
Andrew E. Gao ◽  
Bo Han ◽  
...  
Keyword(s):  
Inversion Layer ◽  
Lower Troposphere ◽  
Specific Humidity ◽  
Radiosonde Data ◽  
Vertical Profiles ◽  
South Pole ◽  
The South ◽  
Yearly Average ◽  
Temperature And Humidity ◽  
Increasing Trends

The vertical profiles and trends of temperature and humidity at the South Pole up to 10 km above mean sea level (amsl) were investigated by using radiosonde data collected from March 2005 to February 2018. During an average year between 2005 and 2018, the highest (lowest) temperature in the lower troposphere was approximately −25 °C (−60 °C) in December (July) at a height of about 500 m above the surface (at the surface). A temperature inversion layer above the surface was found during the whole year but was weaker during the summer, while the inversion layers at the tropopause (about 8 km amsl) mostly disappeared during spring and winter. General warming trends were found at all heights and months, but in a few heights and months cooling trends still occurred (e.g., in September below 7 km amsl). Nevertheless, seasonal and yearly averaged temperatures all presented warming trends: 1.1, 1.3, 0.6, 1.5 and 1.1 °C/decade at the surface, and 0.7, 1.0, 0.3, 0.3 and 0.6 °C/decade for the layer average from the surface to 10 km amsl, for spring, summer, autumn, winter, and yearly average, respectively. Most of the water vapor was confined in the lowermost 3 km of the atmosphere with a maximum of 0.35 g kg−1 in December at a 200 m height above surface, and the specific humidity had the similar characteristic of annual cycle and inversion layers as the temperature. At heights below 5 km amsl, increasing trends of specific humidity larger than 0.02 g kg−1/decade occurred during summer months, including the late spring and early autumn, and the annual mean showed an increasing trend of about 0.01–0.02 g kg−1/decade. Meanwhile, above 5 km amsl, the trends became small and generally less than 0.02 g kg−1/decade in all the months, and beyond 7 km amsl the specific humidity remained almost invariant due to its small moisture content as compared with lower levels. From the surface to 10 km amsl, the specific humidity averaged trends of 0.0062, 0.019, 0.0013, 0.002 and 0.007 g kg−1/decade for spring, summer, autumn, winter and yearly average, respectively.

scholarly journals Comparison between Satellite Water Vapour Observations and Atmospheric Models’ Predictions of the Upper Tropospheric Thermal Radiation

2011 ◽  
Vol 2011 ◽  
pp. 1-15
Author(s):  
J. R. Dim ◽  
T. Y. Nakajima ◽  
T. Takamura ◽  
N. Kikuchi
Keyword(s):  
Water Vapour ◽  
Lower Troposphere ◽  
Satellite Observations ◽  
Department Of Energy ◽  
Atmospheric Models ◽  
Effective Emissivity ◽  
Upper Troposphere ◽  
Clear Sky ◽  
Low Clouds ◽  
The Impact

Atmospheric profiles (temperature, pressure, and humidity) are commonly used parameters for aerosols and cloud properties retrievals. In preparation of the launch of the Global Change Observation Mission-Climate/Second-Generation GLobal Imager (GCOM-C/SGLI) satellite, an evaluation study on the sensitivity of atmospheric models to variations of atmospheric conditions is conducted. In this evaluation, clear sky and above low clouds water vapour radiances of the upper troposphere obtained from satellite observations and those simulated by atmospheric models are compared. The models studied are the Nonhydrostatic ICosahedral Atmospheric Model (NICAM) and the National Center for Environmental Protection/Department Of Energy (NCEP/DOE). The satellite observations are from the Terra/Moderate Resolution Imaging Spectroradiometer (Terra/MODIS) satellite. The simulations performed are obtained through a forward radiative transfer calculation procedure. The resulting radiances are transformed into the upper tropospheric brightness temperature (UTBT) and relative humidity (UTRH). The discrepancies between the simulated data and the observations are analyzed. These analyses show that both the NICAM and the NCEP/DOE simulated UTBT and UTRH have comparable distribution patterns. However the simulations’ differences with the observations are generally lower with the NCEP/DOE than with the NICAM. The NCEP/DOE model outputs very often overestimate the UTBT and therefore present a drier upper troposphere. The impact of the lower troposphere instability (dry convection) on the upper tropospheric moisture and the consequences on the models’ results are evaluated through a thunderstorm and moisture predictor (the K-stability index). The results obtained show a positive relation between the instability and the root mean square error (RMSE: observation versus models). The study of the impact of convective clouds shows that the area covered by these clouds increases with the humidity of the upper troposphere in clear sky and above low clouds, and at the same time, the error between the observations and the models also increases. The impact of the above low clouds heat distribution on the models is studied through the relation between the low clouds cover and their effective emissivity. The models’ error appears to be high at midrange effective emissivity clouds.

scholarly journals Ice nucleating particles over the Eastern Mediterranean measured by unmanned aircraft systems

2017 ◽  
Vol 17 (7) ◽  
pp. 4817-4835 ◽  
Author(s):  
Jann Schrod ◽  
Daniel Weber ◽  
Jaqueline Drücke ◽  
Christos Keleshis ◽  
Michael Pikridas ◽  
...  
Keyword(s):  
Transport Model ◽  
Eastern Mediterranean ◽  
Lower Troposphere ◽  
Ground Level ◽  
Ice Nucleation ◽  
Unmanned Aircraft ◽  
Unmanned Aircraft Systems ◽  
Saharan Dust ◽  
Cloud Formation ◽  
Aircraft Systems

Abstract. During an intensive field campaign on aerosol, clouds, and ice nucleation in the Eastern Mediterranean in April 2016, we measured the abundance of ice nucleating particles (INPs) in the lower troposphere from unmanned aircraft systems (UASs). Aerosol samples were collected by miniaturized electrostatic precipitators onboard the UASs at altitudes up to 2.5 km. The number of INPs in these samples, which are active in the deposition and condensation modes at temperatures from −20 to −30 °C, were analyzed immediately after collection on site using the ice nucleus counter FRIDGE (FRankfurt Ice nucleation Deposition freezinG Experiment). During the 1-month campaign, we encountered a series of Saharan dust plumes that traveled at several kilometers' altitude. Here we present INP data from 42 individual flights, together with aerosol number concentrations, observations of lidar backscattering, dust concentrations derived by the dust transport model DREAM (Dust Regional Atmospheric Model), and results from scanning electron microscopy. The effect of the dust plumes is reflected by the coincidence of INPs with the particulate matter (PM), the lidar signal, and the predicted dust mass of the model. This suggests that mineral dust or a constituent related to dust was a major contributor to the ice nucleating properties of the aerosol. Peak concentrations of above 100 INPs std L−1 were measured at −30 °C. The INP concentration in elevated plumes was on average a factor of 10 higher than at ground level. Since desert dust is transported for long distances over wide areas of the globe predominantly at several kilometers' altitude, we conclude that INP measurements at ground level may be of limited significance for the situation at the level of cloud formation.

scholarly journals The global 3-D distribution of tropospheric aerosols as characterized by CALIOP

2013 ◽  
Vol 13 (6) ◽  
pp. 3345-3361 ◽  
Author(s):  
D. M. Winker ◽  
J. L. Tackett ◽  
B. J. Getzewich ◽  
Z. Liu ◽  
M. A. Vaughan ◽  
...  
Keyword(s):  
Lower Troposphere ◽  
Aerosol Extinction ◽  
Transport Pathways ◽  
3 Dimensional ◽  
Clear Sky ◽  
Tropospheric Aerosol ◽  
Vertical Distributions ◽  
Dimensional Distribution ◽  
Level 3 ◽  
Sky Conditions

Abstract. The CALIOP lidar, carried on the CALIPSO satellite, has been acquiring global atmospheric profiles since June 2006. This dataset now offers the opportunity to characterize the global 3-D distribution of aerosol as well as seasonal and interannual variations, and confront aerosol models with observations in a way that has not been possible before. With that goal in mind, a monthly global gridded dataset of daytime and nighttime aerosol extinction profiles has been constructed, available as a Level 3 aerosol product. Averaged aerosol profiles for cloud-free and all-sky conditions are reported separately. This 6-yr dataset characterizes the global 3-dimensional distribution of tropospheric aerosol. Vertical distributions are seen to vary with season, as both source strengths and transport mechanisms vary. In most regions, clear-sky and all-sky mean aerosol profiles are found to be quite similar, implying a lack of correlation between high semi-transparent cloud and aerosol in the lower troposphere. An initial evaluation of the accuracy of the aerosol extinction profiles is presented. Detection limitations and the representivity of aerosol profiles in the upper troposphere are of particular concern. While results are preliminary, we present evidence that the monthly-mean CALIOP aerosol profiles provide quantitative characterization of elevated aerosol layers in major transport pathways. Aerosol extinction in the free troposphere in clean conditions, where the true aerosol extinction is typically 0.001 km−1 or less, is generally underestimated, however. The work described here forms an initial global 3-D aerosol climatology which we plan to extend and improve over time.

scholarly journals Regional background O<sub>3</sub> and NO<sub>x</sub> in the Houston-Galveston- Brazoria (TX) region: A decadal-scale perspective

2016 ◽  
Author(s):  
Loredana G. Suciu ◽  
Robert J. Griffin ◽  
Caroline A. Masiello
Keyword(s):  
Spatial Scales ◽  
Lower Troposphere ◽  
Principal Component ◽  
Ground Level ◽  
Ambient Air ◽  
Regional Background ◽  
Time Period ◽  
Decadal Scale ◽  
Many Sources ◽  
Local Emissions

Abstract. Ozone (O3) in the lower troposphere is harmful to people and plants, particularly during summer, when photochemistry is the most active and higher temperatures favor local chemistry. Because of its dependence on the volatile organic compounds (VOCs) to nitrogen oxides (NOx) ratio, ground-level O3 is difficult to control locally, where many sources of these precursors contribute to its mixing ratio. In addition to local emissions, chemistry and transport, larger-scale factors also contribute to local O3 and NOx. These additional contributions (often referred to as "regional background") are not well quantified within the Houston-Galveston-Brazoria (HGB) region, impeding more efficient controls on precursor emissions to achieve compliance with the National Ambient Air Quality Standards for O3. In this study, we estimate regional background O3 and NOx in the HGB region and quantify their decadal-scale trends. We use four different approaches based on principal component analysis (PCA) to quantify background O3 and NOx. Three of these approaches consist of independent PCA on both O3 and NOx for both 1-h and 8-h levels to compare our results with previous studies and to highlight the effect of both temporal and spatial scales. In the fourth approach, we co-varied O3, NOx and meteorology. Our results show that the estimation of regional background O3 has less inherent uncertainty when it was constrained by NOx and meteorology, yielding a statistically significant temporal trend of −0.69 ± 0.27 ppb y−1. Likewise, the estimation of regional background NOx trend constrained by O3 and meteorology was −0.04 ± 0.02 ppb y−1. Our best estimates of 17-y average of season-scale background O3 and NOx were 46.72 ± 2.08 ppb and 6.80 ± 0.13 ppb, respectively. Regional background O3 and NOx both have declined over time in the HGB region. This decline is likely caused by a combination of state of Texas controls on precursor emissions since 2007 and the increase in frequency of flow from the Gulf of Mexico over the same time period.

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