Comment on acp-2022-758 - Report DOI Creative Commons
Yaping Shao

Опубликована: Дек. 13, 2022

Abstract. Mineral dust effects upon climate are strongly affected by its particle size distribution (PSD). In particular, the emitted PSD partly controls lifetime and global distribution. Despite extensive research performed on this topic over last decades, there still substantial gaps in our understanding of along with potential variability associated causes. study, we provide insights into saltation size-resolved emission process based measurements obtained during a comprehensive wind erosion field campaign that took place Moroccan Sahara September 2019 context FRontiers minerAloGical coMposition Effects upoN climaTe (FRAGMENT) project. The measurement site located remote ephemeral lake, consisting smooth hard-crusted paved sediment surface surrounded small sand dunes, is characterized strong frequent conditions, relatively low sandblasting efficiencies. Our which thoroughly analyses number mass PSDs both concentration diffusive flux (the latter typically assumed to be equivalent PSD), detects statistically significant dependencies friction velocity (u*), direction type event (regular events vs haboob events). We discuss underlying causes such variability, including effect dry deposition, an enhanced fragmentation aggregates, impact gust front. clearly identify quantify major role played deposition shaping variations, modulated direction-dependent fetch length location u*. estimates show importance relative emission, representing up ∼40 % for super-coarse particles (> 10 μm) ∼20 as ∼5 μm diameter. While attribute enhancement (reduction) submicron (supermicron) u* aggregates could play complementary yet arguably smaller role. additionally find clear differences comparison regular events, i.e., higher (lower) proportion supermicron (submicron) or values, more vigorous coarse fractions. hypothesize these due 1) horizontal (spatial) extent (which fetch), 2) moving front, where maximized, changing proximity variable and/or 3) increased resistance soil observed increases humidity outflow. finally compare predicted original recently updated version Brittle Fragmentation Theory (BFT), accounting emission. For BFT transform optical diameters geometric diameter PSDs, assuming tri-axial ellipsoids index refraction consistent measured properties campaign. obtain substantially lower (higher) PSDs. Also, above ∼2 fraction particles, despite large fraction. All all, results indicate needs adequately considered estimate PSD, even studies limited fine ranges (< μm), particularly locations long fetches.

Язык: Английский

Insights into the size-resolved dust emission from field measurements in the Moroccan Sahara DOI Creative Commons
Cristina González-Flórez, Martina Klose, Andrés Alástuey

и другие.

Atmospheric chemistry and physics, Год журнала: 2023, Номер 23(12), С. 7177 - 7212

Опубликована: Июнь 29, 2023

Abstract. The particle size distribution (PSD) of mineral dust has a strong effect on the impacts climate. However, our understanding emitted PSD, including its variability and fraction super-coarse (diameter >10 µm), remains limited. Here, we provide new insights into size-resolved emission process based field campaign performed in Moroccan Sahara September 2019 context FRontiers minerAloGical coMposition Effects upoN climaTe (FRAGMENT) project. obtained concentration diffusive flux PSDs show significant dependencies upon friction velocity (u*), wind direction type event (regular events versus haboob events). For instance, number sub-micrometre particles increases with u*, along large decrease mass dust. We identify dry deposition, which is modulated by u* fetch length, as potential cause for this PSD variability. Using resistance model constrained observations to estimate deposition thereby also flux, that could represent up ∼90 % (>10 µm) ∼65 small ∼5 µm diameter. Importantly, removing component significantly reduces compared particularly differences between regular are suspected result from smaller variable source during events, and/or an increased soil aggregates fragmentation associated observed increase relative humidity outflow. Finally, invariant estimated brittle theory, obtain substantially higher proportion super-micrometre flux. Overall, results suggest needs be adequately considered even studies limited fine coarse ranges (<10 µm).

Язык: Английский

Процитировано

8
Adhesion theory and model for air humidity impact on dust emission DOI Creative Commons
Yaping Shao

Aeolian Research, Год журнала: 2024, Номер 66, С. 100898 - 100898

Опубликована: Янв. 1, 2024

It has been suggested that air humidity influences dust emission under very dry conditions and adhesion might be the responsible process which changes binding between soil particles. The of is so far poorly understood difficult to quantify. Here, a critical examination relevant studies provided, an model proposed. Both isothermal-kinematic diffusion processes can limit liquid–water water–vapor exchange in soil, but for particle size range concerned aeolian studies, appears limiting process. shows moisture topsoil layers positively correlated with humidity, delays several hours. performance influenced by parameters particularly sensitive equilibrium content. This implies microscopic properties strongly influence adhesion. A new formulation water retention function covering entire also proposed, links pore distribution. Using relationship particle-size pore-size distributions, adhesion-affected grain estimated, defines upper particles moisture. study explains how through why low promotes finer

Язык: Английский

Процитировано

3
Insights into the size-resolved dust emission from field measurements in the Moroccan Sahara DOI Creative Commons
Cristina González-Flórez, Martina Klose, Andrés Alástuey

и другие.

Опубликована: Дек. 5, 2022

Abstract. Mineral dust effects upon climate are strongly affected by its particle size distribution (PSD). In particular, the emitted PSD partly controls lifetime and global distribution. Despite extensive research performed on this topic over last decades, there still substantial gaps in our understanding of along with potential variability associated causes. study, we provide insights into saltation size-resolved emission process based measurements obtained during a comprehensive wind erosion field campaign that took place Moroccan Sahara September 2019 context FRontiers minerAloGical coMposition Effects upoN climaTe (FRAGMENT) project. The measurement site located remote ephemeral lake, consisting smooth hard-crusted paved sediment surface surrounded small sand dunes, is characterized strong frequent conditions, relatively low sandblasting efficiencies. Our which thoroughly analyses number mass PSDs both concentration diffusive flux (the latter typically assumed to be equivalent PSD), detects statistically significant dependencies friction velocity (u*), direction type event (regular events vs haboob events). We discuss underlying causes such variability, including effect dry deposition, an enhanced fragmentation aggregates, impact gust front. clearly identify quantify major role played deposition shaping variations, modulated direction-dependent fetch length location u*. estimates show importance relative emission, representing up ∼40 % for super-coarse particles (> 10 μm) ∼20 as ∼5 μm diameter. While attribute enhancement (reduction) submicron (supermicron) u* aggregates could play complementary yet arguably smaller role. additionally find clear differences comparison regular events, i.e., higher (lower) proportion supermicron (submicron) or values, more vigorous coarse fractions. hypothesize these due 1) horizontal (spatial) extent (which fetch), 2) moving front, where maximized, changing proximity variable and/or 3) increased resistance soil observed increases humidity outflow. finally compare predicted original recently updated version Brittle Fragmentation Theory (BFT), accounting emission. For BFT transform optical diameters geometric diameter PSDs, assuming tri-axial ellipsoids index refraction consistent measured properties campaign. obtain substantially lower (higher) PSDs. Also, above ∼2 fraction particles, despite large fraction. All all, results indicate needs adequately considered estimate PSD, even studies limited fine ranges (< μm), particularly locations long fetches.

Язык: Английский

Процитировано

14
Experimental evidence of dust flux size distribution variation along two consecutive erosion seasons DOI Creative Commons
Royston Fernandes, Sylvain Dupont,

Éric Lamaud

и другие.

Aeolian Research, Год журнала: 2023, Номер 61, С. 100863 - 100863

Опубликована: Фев. 4, 2023

Язык: Английский

Процитировано

2
Impact of Dust Source Patchiness on the Existence of a Constant Dust Flux Layer During Aeolian Erosion Events DOI Creative Commons
Sylvain Dupont, Martina Klose, Mark Irvine

и другие.

Journal of Geophysical Research Atmospheres, Год журнала: 2024, Номер 129(12)

Опубликована: Июнь 11, 2024

Abstract Dust emission fluxes during wind soil erosion are usually estimated using a dust concentration vertical gradient, by assuming constant flux layer between the surface and measurement levels. Here, we investigate existence of this events recorded in Iceland Jordan. Size‐resolved were at three levels 2 4 m eddy‐covariance method. found mainly only two upper Iceland, lower being often stronger richer coarse particles, while Jordan nearly across all The dynamics could not explain absence Iceland. We show that presence stationary source patches related to humidity, created non‐uniform near surface, named roughness sublayer (DRSL), where individual plumes behind each patch interact but do fully mix. lowest level was probably located within ones above, such there emitted became spatially well‐mixed. This explains more intermittent concentration, its low correlation with concentrations particles due their deposition contribution. Our findings highlight importance estimating above blending height whose characteristics depend on patchiness caused humidity or sparse non‐erosive elements.

Язык: Английский

Процитировано

0
Comment on acp-2022-758 DOI Creative Commons
Jasper F. Kok

Опубликована: Янв. 20, 2023

Mineral dust effects upon climate are strongly affected by its particle size distribution (PSD). In particular, the emitted PSD partly controls lifetime and global distribution. Despite extensive research performed on this topic over last decades, there still substantial gaps in our understanding of along with potential variability associated causes. study, we provide insights into saltation size-resolved emission process based measurements obtained during a comprehensive wind erosion field campaign that took place Moroccan Sahara September 2019 context FRontiers minerAloGical coMposition Effects upoN climaTe (FRAGMENT) project. The measurement site located remote ephemeral lake, consisting smooth hard-crusted paved sediment surface surrounded small sand dunes, is characterized strong frequent conditions, relatively low sandblasting efficiencies. Our which thoroughly analyses number mass PSDs both concentration diffusive flux (the latter typically assumed to be equivalent PSD), detects statistically significant dependencies friction velocity (u*), direction type event (regular events vs haboob events). We discuss underlying causes such variability, including effect dry deposition, an enhanced fragmentation aggregates, impact gust front. clearly identify quantify major role played deposition shaping variations, modulated direction-dependent fetch length location u*. estimates show importance relative emission, representing up ∼40 % for super-coarse particles (> 10 μm) ∼20 as ∼5 μm diameter. While attribute enhancement (reduction) submicron (supermicron) u* aggregates could play complementary yet arguably smaller role. additionally find clear differences comparison regular events, i.e., higher (lower) proportion supermicron (submicron) or values, more vigorous coarse fractions. hypothesize these due 1) horizontal (spatial) extent (which fetch), 2) moving front, where maximized, changing proximity variable and/or 3) increased resistance soil observed increases humidity outflow. finally compare predicted original recently updated version Brittle Fragmentation Theory (BFT), accounting emission. For BFT transform optical diameters geometric diameter PSDs, assuming tri-axial ellipsoids index refraction consistent measured properties campaign. obtain substantially lower (higher) PSDs. Also, above ∼2 fraction particles, despite large fraction. All all, results indicate needs adequately considered estimate PSD, even studies limited fine ranges (< μm), particularly locations long fetches.

Язык: Английский

Процитировано

0
Reply on RC2 DOI Creative Commons
Cristina González-Flórez

Опубликована: Май 15, 2023

Abstract. Mineral dust effects upon climate are strongly affected by its particle size distribution (PSD). In particular, the emitted PSD partly controls lifetime and global distribution. Despite extensive research performed on this topic over last decades, there still substantial gaps in our understanding of along with potential variability associated causes. study, we provide insights into saltation size-resolved emission process based measurements obtained during a comprehensive wind erosion field campaign that took place Moroccan Sahara September 2019 context FRontiers minerAloGical coMposition Effects upoN climaTe (FRAGMENT) project. The measurement site located remote ephemeral lake, consisting smooth hard-crusted paved sediment surface surrounded small sand dunes, is characterized strong frequent conditions, relatively low sandblasting efficiencies. Our which thoroughly analyses number mass PSDs both concentration diffusive flux (the latter typically assumed to be equivalent PSD), detects statistically significant dependencies friction velocity (u*), direction type event (regular events vs haboob events). We discuss underlying causes such variability, including effect dry deposition, an enhanced fragmentation aggregates, impact gust front. clearly identify quantify major role played deposition shaping variations, modulated direction-dependent fetch length location u*. estimates show importance relative emission, representing up ∼40 % for super-coarse particles (> 10 μm) ∼20 as ∼5 μm diameter. While attribute enhancement (reduction) submicron (supermicron) u* aggregates could play complementary yet arguably smaller role. additionally find clear differences comparison regular events, i.e., higher (lower) proportion supermicron (submicron) or values, more vigorous coarse fractions. hypothesize these due 1) horizontal (spatial) extent (which fetch), 2) moving front, where maximized, changing proximity variable and/or 3) increased resistance soil observed increases humidity outflow. finally compare predicted original recently updated version Brittle Fragmentation Theory (BFT), accounting emission. For BFT transform optical diameters geometric diameter PSDs, assuming tri-axial ellipsoids index refraction consistent measured properties campaign. obtain substantially lower (higher) PSDs. Also, above ∼2 fraction particles, despite large fraction. All all, results indicate needs adequately considered estimate PSD, even studies limited fine ranges (< μm), particularly locations long fetches.

Язык: Английский

Процитировано

0
Reply on RC3 DOI Creative Commons
Cristina González-Flórez

Опубликована: Май 15, 2023

Abstract. Mineral dust effects upon climate are strongly affected by its particle size distribution (PSD). In particular, the emitted PSD partly controls lifetime and global distribution. Despite extensive research performed on this topic over last decades, there still substantial gaps in our understanding of along with potential variability associated causes. study, we provide insights into saltation size-resolved emission process based measurements obtained during a comprehensive wind erosion field campaign that took place Moroccan Sahara September 2019 context FRontiers minerAloGical coMposition Effects upoN climaTe (FRAGMENT) project. The measurement site located remote ephemeral lake, consisting smooth hard-crusted paved sediment surface surrounded small sand dunes, is characterized strong frequent conditions, relatively low sandblasting efficiencies. Our which thoroughly analyses number mass PSDs both concentration diffusive flux (the latter typically assumed to be equivalent PSD), detects statistically significant dependencies friction velocity (u*), direction type event (regular events vs haboob events). We discuss underlying causes such variability, including effect dry deposition, an enhanced fragmentation aggregates, impact gust front. clearly identify quantify major role played deposition shaping variations, modulated direction-dependent fetch length location u*. estimates show importance relative emission, representing up ∼40 % for super-coarse particles (> 10 μm) ∼20 as ∼5 μm diameter. While attribute enhancement (reduction) submicron (supermicron) u* aggregates could play complementary yet arguably smaller role. additionally find clear differences comparison regular events, i.e., higher (lower) proportion supermicron (submicron) or values, more vigorous coarse fractions. hypothesize these due 1) horizontal (spatial) extent (which fetch), 2) moving front, where maximized, changing proximity variable and/or 3) increased resistance soil observed increases humidity outflow. finally compare predicted original recently updated version Brittle Fragmentation Theory (BFT), accounting emission. For BFT transform optical diameters geometric diameter PSDs, assuming tri-axial ellipsoids index refraction consistent measured properties campaign. obtain substantially lower (higher) PSDs. Also, above ∼2 fraction particles, despite large fraction. All all, results indicate needs adequately considered estimate PSD, even studies limited fine ranges (< μm), particularly locations long fetches.

Язык: Английский

Процитировано

0
Comment on acp-2022-758 DOI Creative Commons
Yaping Shao

Опубликована: Дек. 13, 2022

Abstract. Mineral dust effects upon climate are strongly affected by its particle size distribution (PSD). In particular, the emitted PSD partly controls lifetime and global distribution. Despite extensive research performed on this topic over last decades, there still substantial gaps in our understanding of along with potential variability associated causes. study, we provide insights into saltation size-resolved emission process based measurements obtained during a comprehensive wind erosion field campaign that took place Moroccan Sahara September 2019 context FRontiers minerAloGical coMposition Effects upoN climaTe (FRAGMENT) project. The measurement site located remote ephemeral lake, consisting smooth hard-crusted paved sediment surface surrounded small sand dunes, is characterized strong frequent conditions, relatively low sandblasting efficiencies. Our which thoroughly analyses number mass PSDs both concentration diffusive flux (the latter typically assumed to be equivalent PSD), detects statistically significant dependencies friction velocity (u*), direction type event (regular events vs haboob events). We discuss underlying causes such variability, including effect dry deposition, an enhanced fragmentation aggregates, impact gust front. clearly identify quantify major role played deposition shaping variations, modulated direction-dependent fetch length location u*. estimates show importance relative emission, representing up ∼40 % for super-coarse particles (> 10 μm) ∼20 as ∼5 μm diameter. While attribute enhancement (reduction) submicron (supermicron) u* aggregates could play complementary yet arguably smaller role. additionally find clear differences comparison regular events, i.e., higher (lower) proportion supermicron (submicron) or values, more vigorous coarse fractions. hypothesize these due 1) horizontal (spatial) extent (which fetch), 2) moving front, where maximized, changing proximity variable and/or 3) increased resistance soil observed increases humidity outflow. finally compare predicted original recently updated version Brittle Fragmentation Theory (BFT), accounting emission. For BFT transform optical diameters geometric diameter PSDs, assuming tri-axial ellipsoids index refraction consistent measured properties campaign. obtain substantially lower (higher) PSDs. Also, above ∼2 fraction particles, despite large fraction. All all, results indicate needs adequately considered estimate PSD, even studies limited fine ranges (< μm), particularly locations long fetches.

Язык: Английский

Процитировано

0
Comment on acp-2022-758 - Report DOI Creative Commons
Yaping Shao

Опубликована: Дек. 13, 2022

Abstract. Mineral dust effects upon climate are strongly affected by its particle size distribution (PSD). In particular, the emitted PSD partly controls lifetime and global distribution. Despite extensive research performed on this topic over last decades, there still substantial gaps in our understanding of along with potential variability associated causes. study, we provide insights into saltation size-resolved emission process based measurements obtained during a comprehensive wind erosion field campaign that took place Moroccan Sahara September 2019 context FRontiers minerAloGical coMposition Effects upoN climaTe (FRAGMENT) project. The measurement site located remote ephemeral lake, consisting smooth hard-crusted paved sediment surface surrounded small sand dunes, is characterized strong frequent conditions, relatively low sandblasting efficiencies. Our which thoroughly analyses number mass PSDs both concentration diffusive flux (the latter typically assumed to be equivalent PSD), detects statistically significant dependencies friction velocity (u*), direction type event (regular events vs haboob events). We discuss underlying causes such variability, including effect dry deposition, an enhanced fragmentation aggregates, impact gust front. clearly identify quantify major role played deposition shaping variations, modulated direction-dependent fetch length location u*. estimates show importance relative emission, representing up ∼40 % for super-coarse particles (> 10 μm) ∼20 as ∼5 μm diameter. While attribute enhancement (reduction) submicron (supermicron) u* aggregates could play complementary yet arguably smaller role. additionally find clear differences comparison regular events, i.e., higher (lower) proportion supermicron (submicron) or values, more vigorous coarse fractions. hypothesize these due 1) horizontal (spatial) extent (which fetch), 2) moving front, where maximized, changing proximity variable and/or 3) increased resistance soil observed increases humidity outflow. finally compare predicted original recently updated version Brittle Fragmentation Theory (BFT), accounting emission. For BFT transform optical diameters geometric diameter PSDs, assuming tri-axial ellipsoids index refraction consistent measured properties campaign. obtain substantially lower (higher) PSDs. Also, above ∼2 fraction particles, despite large fraction. All all, results indicate needs adequately considered estimate PSD, even studies limited fine ranges (< μm), particularly locations long fetches.

Язык: Английский

Процитировано

0