scholarly journals Failure and Redemption of Multifilter Rotating Shadowband Radiometer (MFRSR)/Normal Incidence Multifilter Radiometer (NIMFR) Cloud Screening: Contrasting Algorithm Performance at Atmospheric Radiation Measurement (ARM) North Slope of Alaska (NSA) and Southern Great Plains (SGP) Sites

Atmosphere ◽  
2013 ◽  
Vol 4 (3) ◽  
pp. 299-314 ◽  
Author(s):  
Evgueni Kassianov ◽  
Connor Flynn ◽  
Annette Koontz ◽  
Chitra Sivaraman ◽  
James Barnard
Keyword(s):  
Great Plains ◽  
Normal Incidence ◽  
North Slope ◽  
Atmospheric Radiation ◽  
Algorithm Performance ◽  
Southern Great Plains ◽  
North Slope Of Alaska ◽  
Atmospheric Radiation Measurement ◽  
Multifilter Rotating Shadowband Radiometer ◽  
Cloud Screening

scholarly journals Investigation of aerosol–cloud interactions under different absorptive aerosol regimes using Atmospheric Radiation Measurement (ARM) southern Great Plains (SGP) ground-based measurements

2020 ◽  
Vol 20 (6) ◽  
pp. 3483-3501 ◽  
Author(s):  
Xiaojian Zheng ◽  
Baike Xi ◽  
Xiquan Dong ◽  
Timothy Logan ◽  
Yuan Wang ◽  
...  
Keyword(s):  
Great Plains ◽  
Cloud Droplet ◽  
Atmospheric Radiation ◽  
Strong Light ◽  
Southern Great Plains ◽  
Aerosol Cloud ◽  
Atmospheric Radiation Measurement ◽  
The Mean ◽  
Aerosol Cloud Interactions ◽  
Absorbing Aerosols

Abstract. The aerosol indirect effect on cloud microphysical and radiative properties is one of the largest uncertainties in climate simulations. In order to investigate the aerosol–cloud interactions, a total of 16 low-level stratus cloud cases under daytime coupled boundary-layer conditions are selected over the southern Great Plains (SGP) region of the United States. The physicochemical properties of aerosols and their impacts on cloud microphysical properties are examined using data collected from the Department of Energy Atmospheric Radiation Measurement (ARM) facility at the SGP site. The aerosol–cloud interaction index (ACIr) is used to quantify the aerosol impacts with respect to cloud-droplet effective radius. The mean value of ACIr calculated from all selected samples is 0.145±0.05 and ranges from 0.09 to 0.24 at a range of cloud liquid water paths (LWPs; LWP=20–300 g m−2). The magnitude of ACIr decreases with an increasing LWP, which suggests a diminished cloud microphysical response to aerosol loading, presumably due to enhanced condensational growth processes and enlarged particle sizes. The impact of aerosols with different light-absorbing abilities on the sensitivity of cloud microphysical responses is also investigated. In the presence of weak light-absorbing aerosols, the low-level clouds feature a higher number concentration of cloud condensation nuclei (NCCN) and smaller effective radii (re), while the opposite is true for strong light-absorbing aerosols. Furthermore, the mean activation ratio of aerosols to CCN (NCCN∕Na) for weakly (strongly) absorbing aerosols is 0.54 (0.45), owing to the aerosol microphysical effects, particularly the different aerosol compositions inferred by their absorptive properties. In terms of the sensitivity of cloud-droplet number concentration (Nd) to NCCN, the fraction of CCN that converted to cloud droplets (Nd∕NCCN) for the weakly (strongly) absorptive regime is 0.69 (0.54). The measured ACIr values in the weakly absorptive regime are relatively higher, indicating that clouds have greater microphysical responses to aerosols, owing to the favorable thermodynamic condition. The reduced ACIr values in the strongly absorptive regime are due to the cloud-layer heating effect induced by strong light-absorbing aerosols. Consequently, we expect larger shortwave radiative cooling effects from clouds in the weakly absorptive regime than those in the strongly absorptive regime.

scholarly journals Comparison of Vaisala radiosondes RS41 and RS92 at the ARM Southern Great Plains Site

2015 ◽  
Vol 8 (11) ◽  
pp. 11323-11368 ◽  
Author(s):  
M. P. Jensen ◽  
D. Holdridge ◽  
P. Survo ◽  
R. Lehtinen ◽  
S. Baxter ◽  
...  
Keyword(s):  
Great Plains ◽  
Measurement Accuracy ◽  
Atmospheric Temperature ◽  
Atmospheric Radiation ◽  
Atmospheric Conditions ◽  
North Central ◽  
Southern Great Plains ◽  
The Us ◽  
Atmospheric Radiation Measurement

Abstract. In the fall of 2013, the Vaisala RS41-SG (4th generation) radiosonde was introduced as a replacement for the RS92-SGP radiosonde with improvements in measurement accuracy of profiles of atmospheric temperature, humidity and pressure. In order to help characterize these improvements, an intercomparison campaign was undertaken at the US Department of Energy's Atmospheric Radiation Measurement (ARM) Facility site in north Central Oklahoma USA. During 3–8 June 2014, a total of 20 twin-radiosonde flights were performed in a variety of atmospheric conditions representing typical midlatitude continental summertime conditions. The results suggest that the RS92 and RS41 measurements generally agree within manufacturer specified tolerances with notable exceptions when exiting liquid cloud layers where the "wet bulbing" effect is mitigated in the RS41 observations. The RS41 measurements also appear to show a smaller impact from solar heating. These results suggest that the RS41 does provide important improvements, particularly in cloudy conditions, but under most observational conditions the RS41 and RS92 measurements agree within the manufacturer specified limits and so a switch to RS41 radiosondes will have little impact on long-term observational records.

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