TY - JOUR
T1 - Cloud fraction at the ARM SGP site
T2 - Instrument and sampling considerations from 14 years of ARSCL
AU - Kennedy, Aaron D.
AU - Dong, Xiquan
AU - Xi, Baike
N1 - Funding Information:
ARSCL and Mace PI Products were obtained from the Atmospheric Radiation Measurement (ARM) Program sponsored by the U.S. Department of Energy (DOE) Office of Energy Research, Office of Health and Environmental Research, Environmental Sciences Division. This research was primarily suported by DOE ASR program under the grant DE-SC0008468TDD. During this study, authors were also supported by NASA EPSCoR project under grant NNX11AM15A and by NASA CERES project under grant NNX10AI05G at the University of North Dakota. The authors also thank the two anonymous reviewers whose suggestions led to a clearer text.
PY - 2014/1
Y1 - 2014/1
N2 - The Atmospheric Radiation Measurement (ARM) Program Southern Great Plains (SGP) site has a rich history of actively sensed cloud observations. Fourteen years (1997-2010) of observations from the Millimeter Cloud Radar (MMCR), Micropulse Lidar (MPL), and Belfort/Vaisala Ceilometers are used to understand how instrument selection and sampling impacts estimates of Cloud Fraction (CF) at this location. Although all instruments should be used in combination for the best estimates of CF, instrument downtime limits available samples and increases observational errors, demanding that users make sacrifices when calculating CF at longer intervals relevant to climate studies. Selection of MMCR or MMCR + MPL cloud masks changes very little in the overall understanding of total CF. Addition of the MPL increases the 14-year average CF by 9 %, mainly through an increase in optically thin high clouds year-round, and mid-level clouds during the summer months. Splitting the period into two equal 7-year periods reveals negligible change in MMCR + MPL CF. For the MMCR, however, CF deceases by 6.1 %. This sudden change in CF occurs around the time the radar was upgraded, suggesting that this decrease is tied to hardware sensitivity or scanning strategy changes. Users must be cognizant of this and other issues when calculating CF from the variety of observations available at the ARM SGP site.
AB - The Atmospheric Radiation Measurement (ARM) Program Southern Great Plains (SGP) site has a rich history of actively sensed cloud observations. Fourteen years (1997-2010) of observations from the Millimeter Cloud Radar (MMCR), Micropulse Lidar (MPL), and Belfort/Vaisala Ceilometers are used to understand how instrument selection and sampling impacts estimates of Cloud Fraction (CF) at this location. Although all instruments should be used in combination for the best estimates of CF, instrument downtime limits available samples and increases observational errors, demanding that users make sacrifices when calculating CF at longer intervals relevant to climate studies. Selection of MMCR or MMCR + MPL cloud masks changes very little in the overall understanding of total CF. Addition of the MPL increases the 14-year average CF by 9 %, mainly through an increase in optically thin high clouds year-round, and mid-level clouds during the summer months. Splitting the period into two equal 7-year periods reveals negligible change in MMCR + MPL CF. For the MMCR, however, CF deceases by 6.1 %. This sudden change in CF occurs around the time the radar was upgraded, suggesting that this decrease is tied to hardware sensitivity or scanning strategy changes. Users must be cognizant of this and other issues when calculating CF from the variety of observations available at the ARM SGP site.
UR - http://www.scopus.com/inward/record.url?scp=84891663975&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84891663975&partnerID=8YFLogxK
U2 - 10.1007/s00704-013-0853-9
DO - 10.1007/s00704-013-0853-9
M3 - Article
AN - SCOPUS:84891663975
SN - 0177-798X
VL - 115
SP - 91
EP - 105
JO - Theorectical and Applied Climatology
JF - Theorectical and Applied Climatology
IS - 1-2
ER -