scholarly journals Estimation of aerosol direct radiative effects over the mid-latitude North Atlantic from satellite and in situ measurements

1999 ◽  
Vol 26 (12) ◽  
pp. 1731-1734 ◽  
Author(s):  
R. W. Bergstrom ◽  
P. B. Russell
Keyword(s):  
North Atlantic ◽  
In Situ Measurements ◽  
Radiative Effects

scholarly journals Net radiative effects of dust in the tropical North Atlantic based on integrated satellite observations and in situ measurements

2018 ◽  
Vol 18 (15) ◽  
pp. 11303-11322 ◽  
Author(s):  
Qianqian Song ◽  
Zhibo Zhang ◽  
Hongbin Yu ◽  
Seiji Kato ◽  
Ping Yang ◽  
...  
Keyword(s):  
Particle Size ◽  
Refractive Index ◽  
Dust Particle ◽  
North Atlantic ◽  
In Situ Measurements ◽  
Radiative Properties ◽  
Radiative Effects ◽  
Tropical North Atlantic ◽  
Holistic Understanding

Abstract. In this study, we integrate recent in situ measurements with satellite retrievals of dust physical and radiative properties to quantify dust direct radiative effects on shortwave (SW) and longwave (LW) radiation (denoted as DRESW and DRELW, respectively) in the tropical North Atlantic during the summer months from 2007 to 2010. Through linear regression of the CERES-measured top-of-atmosphere (TOA) flux versus satellite aerosol optical depth (AOD) retrievals, we estimate the instantaneous DRESW efficiency at the TOA to be -49.7±7.1 W m−2 AOD−1 and -36.5±4.8 W m−2 AOD−1 based on AOD from MODIS and CALIOP, respectively. We then perform various sensitivity studies based on recent measurements of dust particle size distribution (PSD), refractive index, and particle shape distribution to determine how the dust microphysical and optical properties affect DRE estimates and its agreement with the above-mentioned satellite-derived DREs. Our analysis shows that a good agreement with the observation-based estimates of instantaneous DRESW and DRELW can be achieved through a combination of recently observed PSD with substantial presence of coarse particles, a less absorptive SW refractive index, and spheroid shapes. Based on this optimal combination of dust physical properties we further estimate the diurnal mean dust DRESW in the region of −10 W m−2 at TOA and −26 W m−2 at the surface, respectively, of which ∼ 30 % is canceled out by the positive DRELW. This yields a net DRE of about −6.9 and −18.3 W m−2 at TOA and the surface, respectively. Our study suggests that the LW flux contains useful information on dust particle size, which could be used together with SW observations to achieve a more holistic understanding of the dust radiative effect.

In situ measurements of the NOxdistribution and variability over the eastern North Atlantic

1999 ◽  
Vol 104 (D13) ◽  
pp. 16021-16032 ◽  
Author(s):  
H. Ziereis ◽  
H. Schlager ◽  
P. Schulte ◽  
I. Köhler ◽  
R. Marquardt ◽  
...  
Keyword(s):  
North Atlantic ◽  
In Situ Measurements ◽  
Eastern North Atlantic

scholarly journals Spatiotemporal changes in aerosol properties by hygroscopic growth and impacts on radiative forcing and heating rates during DISCOVER-AQ 2011

2021 ◽  
Vol 21 (15) ◽  
pp. 12021-12048
Author(s):  
Daniel Pérez-Ramírez ◽  
David N. Whiteman ◽  
Igor Veselovskii ◽  
Richard Ferrare ◽  
Gloria Titos ◽  
...  
Keyword(s):  
In Situ Measurements ◽  
Water Soluble ◽  
Hygroscopic Growth ◽  
Radiative Effects ◽  
Heating Rates ◽  
Airborne Measurements ◽  
Lidar Measurements ◽  
Cooling Effects ◽  
Aerosol Hygroscopicity

Abstract. This work focuses on the characterization of vertically resolved aerosol hygroscopicity properties and their direct radiative effects through a unique combination of ground-based and airborne remote sensing measurements during the Column and Vertically Resolved Observations Relevant to Air Quality (DISCOVER-AQ) 2011 field campaign in the Baltimore–Washington DC metropolitan area. To that end, we combined aerosol measurements from a multiwavelength Raman lidar located at NASA Goddard Space Flight Center and the airborne NASA Langley High Spectral Resolution Lidar-1 (HSRL-1) lidar system. In situ measurements aboard the P-3B airplane and ground-based Aerosol Robotic Network – Distributed Regional Aerosol Gridded Observational Network (AERONET-DRAGON) served to validate and complement quantifications of aerosol hygroscopicity from lidar measurements and also to extend the study both temporally and spatially. The focus here is on 22 and 29 July 2011, which were very humid days and characterized by a stable atmosphere and increasing relative humidity with height in the planetary boundary layer (PBL). Combined lidar and radiosonde (temperature and water vapor mixing ratio) measurements allowed the retrieval of the Hänel hygroscopic growth factor which agreed with that obtained from airborne in situ measurements and also explained the significant increase of extinction and backscattering with height. Airborne measurements also confirmed aerosol hygroscopicity throughout the entire day in the PBL and identified sulfates and water-soluble organic carbon as the main species of aerosol particles. The combined Raman and HSRL-1 measurements permitted the inversion for aerosol microphysical properties revealing an increase of particle radius with altitude consistent with hygroscopic growth. Aerosol hygroscopicity pattern served as a possible explanation of aerosol optical depth increases during the day, particularly for fine-mode particles. Lidar measurements were used as input to the libRadtran radiative transfer code to obtain vertically resolved aerosol radiative effects and heating rates under dry and humid conditions, and the results reveal that aerosol hygroscopicity is responsible for larger cooling effects in the shortwave range (7–10 W m−2 depending on aerosol load) near the ground, while heating rates produced a warming of 0.12 K d−1 near the top of PBL where aerosol hygroscopic growth was highest.

scholarly journals Detecting moisture transport pathways to the subtropical North Atlantic free troposphere using paired H<sub>2</sub>O-<i>δ</i>D in situ measurements

2016 ◽  
Vol 16 (7) ◽  
pp. 4251-4269 ◽  
Author(s):  
Yenny González ◽  
Matthias Schneider ◽  
Christoph Dyroff ◽  
Sergio Rodríguez ◽  
Emanuel Christner ◽  
...  
Keyword(s):  
North Atlantic ◽  
In Situ Measurements ◽  
Back Trajectory ◽  
Free Troposphere ◽  
Night Time ◽  
Humid Air ◽  
Transport Pathways ◽  
Air Masses ◽  
Dry Convection

Abstract. We present two years of in situ measurements of water vapour (H2O) and its isotopologue ratio (δD, the standardized ratio between H216O and HD16O), made at two remote mountain sites on Tenerife in the subtropical North Atlantic. We show that the data – if measured during night-time – are well representative for the lower/middle free troposphere. We use the measured H2O-δD pairs, together with dust measurements and back trajectory modelling for analysing the moisture pathways to this region. We can identify four principally different transport pathways. The air mass transport from high altitudes and high latitudes shows two different scenarios. The first scenario brings dry air masses to the stations, as the result of condensation events occurring at low temperatures. The second scenario brings humid air masses to the stations, due to cross-isentropic mixing with lower-level and more humid air during transport since last condensation (LC). The third pathway is transportation from lower latitudes and lower altitudes, whereby we can identify rain re-evaporation as an occasional source of moisture. The fourth pathway is linked to the African continent, where during summer, dry convection processes over the Sahara very effectively inject humidity from the boundary layer to higher altitudes. This so-called Saharan Air Layer (SAL) is then advected westward over the Atlantic and contributes to moisten the free troposphere. We demonstrate that the different pathways leave distinct fingerprints on the measured H2O-δD pairs.

scholarly journals In situ measurements of cloud microphysical and aerosol properties during the break-up of stratocumulus cloud layers in cold air outbreaks over the North Atlantic

2018 ◽  
Vol 18 (23) ◽  
pp. 17191-17206 ◽  
Author(s):  
Gary Lloyd ◽  
Thomas W. Choularton ◽  
Keith N. Bower ◽  
Martin W. Gallagher ◽  
Jonathan Crosier ◽  
...  
Keyword(s):  
Boundary Layer ◽  
North Atlantic ◽  
In Situ Measurements ◽  
Cold Air ◽  
The North ◽  
The North Atlantic ◽  
Break Up ◽  
The Uk ◽  
Cold Air Outbreaks

Abstract. A key challenge for numerical weather prediction models is representing boundary layer clouds in cold air outbreaks (CAOs). One important aspect is the evolution of microphysical properties as stratocumulus transitions to open cellular convection. Abel et al. (2017) have shown, for the first time from in situ field observations, that the break-up in CAOs over the eastern Atlantic may be controlled by the development of precipitation in the cloud system while the boundary layer becomes decoupled. This paper describes that case and examines in situ measurements from three more CAOs. Flights were conducted using the UK Facility for Airborne Atmospheric Measurements (FAAM) British Aerospace-146 (BAe-146) aircraft in the North Atlantic region around the UK, making detailed microphysical measurements in the stratiform boundary layer. As the cloudy boundary layer evolves prior to break-up, increasing liquid water paths (LWPs) and drop sizes and the formation of liquid precipitation are observed. Small numbers of ice particles, typically a few per litre, are also observed. Eventually LWPs reduce significantly due to loss of water from the stratocumulus cloud (SC) layer. In three of the cases, aerosols are removed from the boundary layer across the transition. This process appears to be similar to those observed in warm clouds and pockets of open cells (POCs) in the subtropics. After break-up, deeper convective clouds form with bases warm enough for secondary ice production (SIP), leading to rapid glaciation. It is concluded that the precipitation is strongly associated with the break-up, with both weakening of the capping inversion and boundary layer decoupling also observed.

scholarly journals Estimation of the oceanic pCO<sub>2</sub> in the North Atlantic from VOS lines in-situ measurements: parameters needed to generate seasonally mean maps

2007 ◽  
Vol 25 (11) ◽  
pp. 2247-2257 ◽  
Author(s):  
C. Jamet ◽  
C. Moulin ◽  
N. Lefèvre
Keyword(s):  
North Atlantic ◽  
Mixed Layer Depth ◽  
Chlorophyll Concentration ◽  
In Situ Measurements ◽  
High Pco2 ◽  
Physical Parameters ◽  
Data Set ◽  
The North ◽  
The North Atlantic

Abstract. Automated instruments on board Volunteer Observing Ships (VOS) have provided high-frequency pCO2 measurements over basin-wide regions for a decade or so. In order to estimate regional air-sea CO2 fluxes, it is necessary to interpolate between in-situ measurements to obtain maps of the marine pCO2. Such an interpolation remains, however, a difficult task because VOS lines are too distant from each other to capture the high pCO2 variability. Relevant physical parameters available at large scale are thus necessary to serve as a guide to estimate the pCO2 values between the VOS lines. Satellites do not measure pCO2 but they give access to parameters related to the processes that control its variability, such as sea surface temperature (SST). In this paper we developed a method to compute pCO2 maps using satellite data (SST and CHL, the chlorophyll concentration), combined with a climatology of the mixed-layer depth (MLD). Using 15 401 measurements of surface pCO2 acquired in the North Atlantic between UK and Jamaica, between June 1994 and August 1995, we show that the parameterization of pCO2 as a function of SST, CHL and MLD yields more realistic pCO2 values than parameterizations that have been widely used in the past, based on SST, latitude, longitude or SST only. This parameterization was then used to generate seasonal maps of pCO2 over the North Atlantic. Results show that our approach yields the best marine pCO2 estimates, both in terms of absolute accuracy, when compared with an independent data set, and of geographical patterns, when compared to the climatology of Takahashi et al. (2002). This suggests that monitoring the seasonal variability of pCO2 over basin-wide regions is possible, provided that sufficient VOS lines are available.

scholarly journals Spatiotemporal changes in aerosol properties by hygroscopic growth and impacts on radiative forcing and heating rates during DISCOVER-AQ 2011

2021 ◽  
Author(s):  
Daniel Pérez-Ramírez ◽  
David N. Whiteman ◽  
Igor Veselovskii ◽  
Richard Ferrare ◽  
Gloria Titos ◽  
...  
Keyword(s):  
In Situ Measurements ◽  
Water Soluble ◽  
Hygroscopic Growth ◽  
Radiative Effects ◽  
Heating Rates ◽  
Airborne Measurements ◽  
Lidar Measurements ◽  
Cooling Effects ◽  
Aerosol Hygroscopicity

Abstract. This work focuses on the characterization of vertically-resolved aerosol hygroscopicity properties and their direct radiative effects through a unique combination of ground-based and airborne remote sensing measurements during the DISCOVER-AQ 2011 field campaign in the Washington D.C. – Baltimore metropolitan area. To that end, we combined measurements from a multiwavelength Raman lidar located at NASA Goddard Space Flight Center and the airborne NASA Langley HSRL-1 lidar system. In-situ measurements on board the P-3B airplane and ground-based AERONET-DRAGON served to validate and complement quantifications of aerosol hygroscopicity from lidar measurements and also to extend the study both temporally and spatially. The focus here is on the 22nd and 29th of July, 2011 which were very humid days and characterized by a stable atmosphere and increasing relative humidity with height in the planetary boundary layer (PBL). Combined lidar and radiosonde measurements allowed the retrieval of the Hänel hygroscopic growth factor which agreed with that obtained from airborne in-situ measurements, and also explained the significant increase of extinction and backscattering with height. Airborne measurements also confirmed aerosol hygroscopicity throughout the entire day in the PBL and identified sulfates and water soluble organic carbon as the main species of aerosol particles. The combined Raman and HSRL-1 measurements permitted the inversion for aerosol microphysical properties revealing an increase of particle radius with altitude consistent with hygroscopic growth. Aerosol hygroscopicity was identified as the main reason to explain aerosol optical depth increases during the day, particularly for fine mode particles. Lidar measurements were used as input to the libRadtram radiative transfer code to obtain vertically-resolved aerosol radiative effects and heating rates under dry and humid conditions, and the results reveal that aerosol hygroscopicity is responsible for larger cooling effects in the shortwave range (7–10 W/m2 depending on aerosol load) near the ground, while heating rates produced a warming of 0.12 K/day near the top of PBL where aerosol hygroscopic growth was highest.

scholarly journals In-Situ Measurements of Cloud Microphysical and Aerosol Properties during the Breakup of Stratocumulus Cloud Layers in Cold Air Outbreaks over the North Atlantic

2018 ◽  
Author(s):  
Gary Lloyd ◽  
Thomas W. Choularton ◽  
Keith N. Bower ◽  
Martin W. Gallagher ◽  
Jonathan Crosier ◽  
...  
Keyword(s):  
Boundary Layer ◽  
North Atlantic ◽  
Weather Prediction ◽  
In Situ Measurements ◽  
Cold Air ◽  
The North ◽  
The North Atlantic ◽  
The Uk ◽  
Cold Air Outbreaks

Abstract. A key challenge for numerical weather prediction models is representing boundary layer clouds in Cold Air Outbreaks. One important aspect is the evolution of microphysical properties as stratocumulus transitions to open cellular convection. Abel et al. (2017) has for the first time from in-situ field observations shown that the breakup in cold air outbreaks over the eastern Atlantic may be controlled by the development of precipitation in the cloud system while the boundary layer becomes decoupled. This paper describes that case and examines in-situ measurements from 3 more cold air outbreaks. Flights were conducted using the UK FAAM BAe-146 aircraft in the North Atlantic region around the UK making detailed microphysical measurements in the stratiform boundary layer. As the cloudy boundary layer evolves prior to breakup, increasing liquid water paths, drop sizes and the formation of liquid precipitation is observed. Small numbers of ice particles are also observed. Eventually LWPs reduce significantly due to loss of water from the Sc cloud layer. In 3 of the cases, aerosols are removed from the boundary layer across the transition. This process appears to be similar to those observed in warm clouds and pockets of open cells in the subtropics. After breakup, deeper convective clouds form with bases warm enough for secondary ice production, leading to rapid glaciation. It is concluded that the precipitation is strongly associated with the break-up, with both weakening of the capping inversion and boundary layer decoupling also observed.

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