One year of CNR-IMAA multi-wavelength Raman lidar measurements in coincidence with CALIPSO overpasses: Level 1 products comparison

We investigate the seasonality in aerosols over the Southeastern United States using observations from several satellite instruments (MODIS, MISR, CALIOP) and surface network sites (IMPROVE, SEARCH, AERONET). We find that the strong summertime enhancement in satellite-observed aerosol optical depth (AOD) (factor 2–3 enhancement over wintertime AOD) is not present in surface mass concentrations (25–55% summertime enhancement). Goldstein et al. (2009) previously attributed this seasonality in AOD to biogenic organic aerosol; however, surface observations show that organic aerosol only accounts for ∼35% of fine particulate matter (smaller than 2.5 μm in aerodynamic diameter, PM_2.5) and exhibits similar seasonality to total surface PM_2.5. The GEOS-Chem model generally reproduces these surface aerosol measurements, but underrepresents the AOD seasonality observed by satellites. We show that seasonal differences in water uptake cannot sufficiently explain the magnitude of AOD increase. As CALIOP profiles indicate the presence of additional aerosol in the lower troposphere (below 700 hPa), which cannot be explained by vertical mixing, we conclude that the discrepancy is due to a missing source of aerosols above the surface layer in summer

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“…Other studies have also found good agreement between CALIOP and ground-based lidar measurements (e.g., Mamouri et al, 2009;Mona et al, 2009).…”

Section: Satellite Observationsmentioning

confidence: 78%

Aerosol loading in the Southeastern United States: reconciling surface and satellite observations

Ford

Heald

2013

Atmos. Chem. Phys.

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“…Since the launch of CALIPSO, several studies have been conducted validating the CALIOP data products (Mona et al, 2009;Mamouri et al, 2009;Kim et al, 2008). Some promising results were also published by McGill et al (2007) qualitatively comparing measurements from CALIOP to the Cloud Profiling Lidar (CPL) deployed on the ER-2 aircraft.…”

Section: Introductionmentioning

confidence: 86%

“…In clear sky conditions, Mona et al (2009), found CALIOP to bias slightly low in the free troposphere and very low in the PBL (below 2.5 km). Pappalardo et al (2010) show similar results from comparisons between several EARLINET lidars and CALIOP with similar results.…”

Section: Discussionmentioning

confidence: 99%

“…Therefore, a subset of the 86 flight comparison dataset was considered with tighter constraints on temporal separation of HSRL and CALIOP. In this subset, only HSRL data within 45 min of the CALIOP closest point of approach were considered, which is slightly larger than the 30 min criterion used by Mona et al (2009). Furthermore, because clouds are highly variable in the atmosphere both HSRL and CALIOP data were screened for clouds at all altitudes using both the CALIOP VFM and HSRL cloud detection routine (detected as sharp gradients in the raw signals using a three point Haar wavelet covariance transform, Gamage and Hagelberg, 1993), as well as a manual inspection to ensure that only cloud-free profiles were used in the comparison.…”

Section: Altitude Dependence Of the Caliop 532 Nm Total Attenuated Bamentioning

confidence: 99%

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Assessment of the CALIPSO Lidar 532 nm attenuated backscatter calibration using the NASA LaRC airborne High Spectral Resolution Lidar

et al. 2011

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To better assess the range of conditions under which CALIOP data products are produced, these validation flights were conducted under both daytime and nighttime lighting conditions, in multiple seasons, and over a large range of latitudes and aerosol and cloud conditions. This paper presents a quantitative assessment of the CALIOP 532 nm calibration (through the 532 nm total attenuated backscatter) using internally calibrated airborne HSRL underflight data and is the most extensive study of CALIOP 532 nm calibration. Results show that HSRL and CALIOP 532 nm total attenuated backscatter agree on average within 2.7% ± 2.1% (CALIOP lower) at night and within 2.9% ± 3.9% (CALIOP lower) during the day, demonstrating the accuracy of the CALIOP 532 nm calibration algorithms. Additionally, comparisons with HSRL show consistency of the CALIOP calibration before and after the laser switch in 2009 as well as improvements in the daytime version 3.01 calibration scheme compared with the version 2 calibration scheme. Potential biases and uncertainties in the methodology relevant to validating satellite lidar measurements with an airborne lidar system are Correspondence to: R. R. Rogers (raymond.r.rogers@nasa.gov) discussed and found to be less than 4.5% ± 3.2% for this validation effort with HSRL. Results from this study are also compared with prior assessments of the CALIOP 532 nm attenuated backscatter calibration.

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“…Therefore, in the following we compare the attenuated backscatter coefficient available from all the instruments, and different calibration techniques according to the availability of the raw signals. The attenuated backscatter coefficient β is calculated using the Raman lidar retrieval of extinction for the MUSA lidar is defined as (Mona et al, 2009):…”

Section: Comparison Of Lidar and Ceilometer Attenuated Backscatter Comentioning

confidence: 99%

Ceilometer aerosol profiling versus Raman lidar in the frame of the INTERACT campaign of ACTRIS

et al. 2015

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Abstract. Despite their differences from more advanced and more powerful lidars, the low construction and operation cost of ceilometers (originally designed for cloud base height monitoring) has fostered their use for the quantitative study of aerosol properties. The large number of ceilometers available worldwide represents a strong motivation to investigate both the extent to which they can be used to fill in the geographical gaps between advanced lidar stations and also how their continuous data flow can be linked to existing networks of the more advanced lidars, like EARLINET (European Aerosol Research Lidar Network).In this paper, multi-wavelength Raman lidar measurements are used to investigate the capability of ceilometers to provide reliable information about atmospheric aerosol properties through the INTERACT (INTERcomparison of Aerosol and Cloud Tracking) campaign carried out at the CNR-IMAA Atmospheric Observatory (760 m a.s.l., 40.60 • N, 15.72 • E), in the framework of the ACTRIS (Aerosol Clouds Trace gases Research InfraStructure) FP7 project. This work is the first time that three different commercial ceilometers with an advanced Raman lidar are compared over a period of 6 months. The comparison of the attenuated backscatter coefficient profiles from a multiwavelength Raman lidar and three ceilometers (CHM15k, CS135s, CT25K) reveals differences due to the expected discrepancy in the signal to noise ratio (SNR) but also due to changes in the ambient temperature on the short and midterm stability of ceilometer calibration. Therefore, technological improvements are needed to move ceilometers towards operational use in the monitoring of atmospheric aerosols in the low and free troposphere.

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One year of CNR-IMAA multi-wavelength Raman lidar measurements in coincidence with CALIPSO overpasses: Level 1 products comparison

Cited by 84 publications

References 32 publications

Aerosol loading in the Southeastern United States: reconciling surface and satellite observations

Aerosol loading in the Southeastern United States: reconciling surface and satellite observations

Assessment of the CALIPSO Lidar 532 nm attenuated backscatter calibration using the NASA LaRC airborne High Spectral Resolution Lidar

Ceilometer aerosol profiling versus Raman lidar in the frame of the INTERACT campaign of ACTRIS

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