Vertical distribution of aerosol optical properties based on aircraft measurements over the Loess Plateau in China

2015 ◽  
Vol 34 ◽  
pp. 44-56 ◽  
Author(s):  
Junxia Li ◽  
Xingang Liu ◽  
Liang Yuan ◽  
Yan Yin ◽  
Zhanqing Li ◽  
...  
Keyword(s):  
Optical Properties ◽  
Vertical Distribution ◽  
Loess Plateau ◽  
Aircraft Measurements ◽  
The Loess Plateau ◽  
Aerosol Optical Properties

scholarly journals Vertical distribution of soil available phosphorus and soil available potassium in the critical zone on the Loess Plateau, China

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Hanyang Tian ◽  
Jiangbo Qiao ◽  
Yuanjun Zhu ◽  
Xiaoxu Jia ◽  
Ming’an Shao
Keyword(s):  
Vertical Distribution ◽  
Loess Plateau ◽  
Clay Content ◽  
Exponential Model ◽  
Critical Zone ◽  
Available Phosphorus ◽  
Soil Core ◽  
The Loess Plateau ◽  
Deep Soil ◽  
Soil Available Phosphorus

AbstractSoil available phosphorus (SAP) and soil available potassium (SAK) are important elements in the growth of plants. However, limited data are available regarding the vertical distribution of SAP and SAK in deep soil profiles. In this study, we investigated the vertical variations in SAP and SAK in the critical zone on the Loess Plateau (50–200 m), China, by using classical statistical and geostatistical methods. The soil samples were collected from the top of the soil profile down to the bedrock by soil core drilling at five typical sites. SAP decreased throughout the profile. Whereas the SAK exhibited an increasing trend at all sites. The mean SAP concentration ranged from 0.94 to 32.56 mg kg–1 at the sampling sites and the SAK concentration ranged from 44.51 to 229.31 mg kg–1. At all of the sampling sites, SAK was significantly positively correlated with the depth and clay content, but there was a significantly negative correlation between the SAK and the sand content. The exponential model could fit most variograms of SAP and SAK at all sampling sites. The results obtained in this study to improve our comprehension of the SAP or SAK distribution conditions on the Loess Plateau, which is important for reasonable fertilizer application and vegetation planting practices.

scholarly journals Statistical evaluation of aerosol retrievals from AERONET using in-situ aircraft measurements

2011 ◽  
Vol 11 (10) ◽  
pp. 29003-29054 ◽  
Author(s):  
A. R. Esteve ◽  
J. A. Ogren ◽  
P. J. Sheridan ◽  
E. Andrews ◽  
B. N. Holben ◽  
...  
Keyword(s):  
Optical Properties ◽  
Asymmetry Parameter ◽  
Statistical Evaluation ◽  
Single Scattering ◽  
Single Scattering Albedo ◽  
Aircraft Measurements ◽  
Aerosol Optical Properties ◽  
Total Light ◽  
The One

Abstract. Aerosol optical properties were measured by NOAA's Airborne Aerosol Observatory over Bondville, Illinois, during more than two years using a light aircraft. Measured properties included total light scattering, backscattering, and absorption, while calculated parameters included aerosol optical depth (AOD), Ångström exponent, single-scattering albedo, hemispheric backscatter fraction, asymmetry parameter, and submicrometer mode fraction of scattering. The in-situ aircraft measurements are compared here with AERONET measurements and retrievals of the aerosol optical properties at the same location. The comparison reveals discrepancies between the aerosol properties retrieved from AERONET and from in-situ aircraft measurements. These discrepancies are smaller for the AOD, while the biggest discrepancies are for the single-scattering albedo, hemispheric backscatter fraction, and asymmetry parameter. Possible sources of discrepancy between the AOD measured by AERONET and the one calculated from the in-situ aircraft measurements are investigated. The largest portion of the AOD discrepancy is likely due to an incorrect adjustment to ambient RH of the scattering coefficient. Another significant part (along with uncertain nephelometer truncation corrections) may come from the possibility that there might be less aerosol below the lowest flight altitude or that the aircraft inlet excludes aerosol particles larger than 5–7 μm diameter.

scholarly journals Quantifying the sensitivity of aerosol optical properties to the parameterizations of physico-chemical processes during the 2010 Russian wildfires and heatwave

2020 ◽  
Author(s):  
Laura Palacios-Peña ◽  
Philip Stier ◽  
Raquel Lorente-Plazas ◽  
Pedro Jiménez-Guerrero
Keyword(s):  
Optical Properties ◽  
Relative Humidity ◽  
Vertical Distribution ◽  
Dry Deposition ◽  
Linear Response ◽  
Convective Transport ◽  
The Other ◽  
Aerosol Optical Properties ◽  
Other Hand ◽  
Non Linear

Abstract. The impact of aerosol-radiation and aerosol-clouds interactions on the radiative forcing is subject to large uncertainties. This is caused by the limited understanding of aerosol optical properties and the role of aerosols as cloud condensation/ice nuclei (CCN/IN). On the other hand, aerosol optical properties and vertical distribution are highly related and their uncertainties come from different processes. This work attempts to quantify the sensitivity of aerosol optical properties (i.e. aerosol optical depth; AOD) and their vertical distribution (using the extinction coefficient, backscatter coefficient, and concentrations species profiles) to key processes. In order to achieve this objective sensitivity tests have been carried out, using the WRF-Chem regional fully coupled model by modifying the dry deposition, sub-grid convective transport, relative humidity and wet scavenging. The 2010 Russian heatwave/wildfire episode has been selected as case study. Results indicate that AOD is sensitive to these key processes in the following order of importance: 1) modification of relative humidity, causing AOD differences up to 0.6; 2) modification of vertical convection transport with AOD differences around  0.4; and 3) the dry deposition with AOD differences up to −0.35 and 0.3. Moreover, these AOD changes exhibit a non-linear response. Both, an increase and a decrease in the RH result in higher AOD values. On the other hand, both, the increase and offset of the sub-grid convective transport lead to a reduction in the AOD over the fire area. In addition, a similar non-linear response is found when reducing the dry deposition velocity; in particular, for the accumulation mode where the concentration of several species increases (while a decrease might be expected). These non-linear responses are highly dependent on the equilibrium of the thermodynamics system sulphate-nitrate-SOA (secondary organic aerosol). In this sense, small changes in the concentration of one species can strongly affect others, finally affecting aerosol optical properties. Changes in this equilibrium could come from modifications in relative humidity, dry deposition or vertical convective transport. By itself, dry deposition also presents a high uncertainty influencing the AOD representation.

scholarly journals Quantifying the sensitivity of aerosol optical properties to the parameterizations of physico-chemical processes during the 2010 Russian wildfires and heatwave

2020 ◽  
Vol 20 (16) ◽  
pp. 9679-9700
Author(s):  
Laura Palacios-Peña ◽  
Philip Stier ◽  
Raquel Lorente-Plazas ◽  
Pedro Jiménez-Guerrero
Keyword(s):  
Optical Properties ◽  
Relative Humidity ◽  
Vertical Distribution ◽  
Dry Deposition ◽  
Nonlinear Response ◽  
Convective Transport ◽  
The Other ◽  
Aerosol Optical Properties ◽  
Other Hand ◽  
The Impact

Abstract. The impact of aerosol–radiation and aerosol–cloud interactions on the radiative forcing is subject to large uncertainties. This is caused by the limited understanding of aerosol optical properties and the role of aerosols as cloud condensation/ice nuclei (CCN/IN). On the other hand, aerosol optical properties and vertical distribution are highly related, and their uncertainties come from different processes. This work attempts to quantify the sensitivity of aerosol optical properties (i.e. aerosol optical depth; AOD) and their vertical distribution (using the extinction coefficient, backscatter coefficient, and concentrations' species profiles) to key processes. In order to achieve this objective, sensitivity tests have been carried out, using the WRF-Chem regional fully coupled model by modifying the dry deposition, sub-grid convective transport, relative humidity, and wet scavenging. The 2010 Russian heatwave–wildfires episode has been selected as case study. Results indicate that AOD is sensitive to these key processes in the following order of importance: (1) modification of relative humidity, causing AOD differences of up to 0.6; (2) modification of vertical convection transport with AOD differences around −0.4; and (3) the dry deposition with AOD absolute differences of up to −0.35 and 0.3. Moreover, these AOD changes exhibit a nonlinear response. Both an increase and a decrease in the RH result in higher AOD values. On the other hand, both the increase and offset of the sub-grid convective transport lead to a reduction in the AOD over the fire area. In addition, a similar nonlinear response is found when reducing the dry deposition velocity; in particular, for the accumulation mode where the concentration of several species increases (while a decrease might be expected). These nonlinear responses are highly dependent on the equilibrium of the thermodynamics system sulfate–nitrate–SOA (secondary organic aerosol). In this sense, small changes in the concentration of one species can strongly affect others, finally affecting aerosol optical properties. Changes in this equilibrium could come from modifications in relative humidity, dry deposition, or vertical convective transport. By itself, dry deposition also presents a high uncertainty influencing the AOD representation.

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