scholarly journals A cautionary use of DCC as a solar calibration target: explaining the regional difference in DCC reflectivity

2015 ◽  
Vol 8 (3) ◽  
pp. 2409-2436
Author(s):  
M.-J. Choi ◽  
B. J. Sohn
Keyword(s):  
Regional Difference ◽  
Satellite Observation ◽  
Western Pacific ◽  
South American ◽  
Convective Clouds ◽  
Ice Water Path ◽  
Deep Convective Clouds ◽  
The Tropics ◽  
Ice Water ◽  
The Western Pacific

Abstract. This study attempted to explain why deep convective clouds (DCCs) over the western Pacific are generally darker than those found over tropical African and South American land regions. For defining 1 km pixel DCCs in this study, 205 K of Aqua-MODIS brightness temperature at 11 μm (TB11) was used as a criterion. Corresponding MODIS-measured reflectivities at 0.645 μm were examined, and an analysis of collocated Cloud Profile Radar (CPR) onboard CloudSat and Cloud Aerosol Lidar Infrared Pathfinder Satellite Observation (CALIPSO) measurements and derived cloud products was conducted. From an analysis of the four January months of 2007–2010, a distinct difference in ice water path (IWP) between the western Pacific and the two tropical land regions was demonstrated. Small but meaningful differences in the effective radius were also found. The results led to a conjecture that smaller IWP over the western Pacific than over the tropical land regions is the main cause of smaller reflectivity there. This finding suggests that regionally different reflectivity of DCCs over the tropics up to 5% on average are to be counted when those DCCs are used for the solar channel calibration.

scholarly journals Explaining darker deep convective clouds over the western Pacific than over tropical continental convective regions

2015 ◽  
Vol 8 (11) ◽  
pp. 4573-4585 ◽  
Author(s):  
B.-J. Sohn ◽  
M.-J. Choi ◽  
J. Ryu
Keyword(s):  
Single Layer ◽  
Satellite Observation ◽  
Cloud Microphysics ◽  
Western Pacific ◽  
South American ◽  
Convective Clouds ◽  
Deep Convective Clouds ◽  
Ocean Region ◽  
Ice Water ◽  
The Western Pacific

Abstract. This study attempted to explain why deep convective clouds (DCCs) over the western Pacific are generally darker than those found over tropical African and South American land regions. The western Pacific domain was further divided into its land and ocean regions to deduce the general differences in DCC characteristics between convectively active tropical land and ocean regions. DCC in this study is defined as a single-layer cloud whose thickness is greater than 15 km, and it is determined from CloudSat-measured reflectivity profiles. Corresponding MODIS-measured reflectivities at 0.645 μm were examined, along with the analysis of cloud products from Cloud Aerosol Lidar Infrared Pathfinder Satellite Observation (CALIPSO) measurements. From an analysis of the four January months of 2007–2010, a distinct difference in ice water path (IWP) between the ocean region of the western Pacific and the three tropical land regions was revealed. Distinct differences in the effective radius between land and ocean were also found. The findings lead to a conclusion that smaller IWP over the western Pacific ocean region than over the tropical land regions, which should be caused by different cloud microphysics between land and ocean, is the main cause of smaller reflectivity there.

Galaxias maculatus: An explanation of its biogeography

1996 ◽  
Vol 47 (6) ◽  
pp. 845 ◽  
Author(s):  
TM Berra ◽  
LELM Crowley ◽  
W Ivantsoff ◽  
PA Fuerst
Keyword(s):  
Gene Flow ◽  
New Zealand ◽  
Oceanic Islands ◽  
Western Pacific ◽  
Disjunct Distribution ◽  
South American ◽  
Salt Tolerant ◽  
Galaxias Maculatus ◽  
Break Up ◽  
The Western Pacific

Galaxias maculatus is a small diadromous fish found in Australia, New Zealand, South America and on some oceanic islands. Two hypotheses have been advanced to explain this widespread, disjunct distribution. McDowall promoted dispersal through the sea of salt-tolerant juveniles but Rosen and others claimed that the distribution reflected the break-up of Gondwana and subsequent drift of the southern continents. Allozyrne electrophoresis of muscle extracts of specimens of Galaxias maculatus from eastern and western Australia, New Zealand and Chile was used to test the hypothesis that populations of G. maculatus from the western Pacific and the eastern Pacific do not differ genetically. FST based on allele frequencies and genotypes was 0.14, suggesting only minor differentiation between eastern and western Pacific populations. Minor differentiation in allele frequency existed at some loci, but no fixation of alternative alleles has occurred. The populations examined appear to be part of the same gene pool, indicating that gene flow via dispersal through the sea occurs today. It is unlikely that South American and Australasian populations would be conspecific if they have exchanged no migrants since the break-up of Gondwana at the end of the Mesozoic.

scholarly journals Microphysical Processes Producing High Ice Water Contents (HIWCs) in Tropical Convective Clouds during the HAIC-HIWC Field Campaign: Evaluation of Simulations Using Bulk Microphysical Schemes

2020 ◽  
Author(s):  
Yongjie Huang ◽  
Wei Wu ◽  
Greg M. McFarquhar ◽  
Xuguang Wang ◽  
Hugh Morrison ◽  
...  
Keyword(s):  
Water Content ◽  
Ice Crystals ◽  
Field Campaign ◽  
Campaign Evaluation ◽  
Convective Clouds ◽  
Ice Water Content ◽  
Microphysical Processes ◽  
The Tropics ◽  
Ice Water ◽  
Water Contents

Abstract. Regions with high ice water content (HIWC), composed of mainly small ice crystals, frequently occur over convective clouds in the tropics. Such regions can have median mass diameters (MMDs)

scholarly journals Carbon and hydrogen isotopic ratios of atmospheric methane in the upper troposphere over the Western Pacific

2012 ◽  
Vol 12 (4) ◽  
pp. 9035-9077 ◽  
Author(s):  
T. Umezawa ◽  
T. Machida ◽  
K. Ishijima ◽  
H. Matsueda ◽  
Y. Sawa ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Isotopic Ratio ◽  
Lower Troposphere ◽  
Western Pacific ◽  
Boreal Summer ◽  
Additional Contribution ◽  
Mixing Ratio ◽  
Upper Troposphere ◽  
The Tropics ◽  
The Western Pacific

Abstract. We present the mixing ratio, δ13C and δD of atmospheric CH4 using commercial aircraft in the upper troposphere (UT) over the Western Pacific for the period December 2005–September 2010. The observed results were compared with those obtained using commercial container ships in the lower troposphere (LT) over the same region. In the Northern Hemisphere (NH), the UT CH4 mixing ratio shows high values in the boreal summer–autumn, when the LT CH4 mixing ratio reaches a seasonal minimum. From tagged tracer experiments made using an atmospheric chemistry transport model, we found that such high CH4 values are due to rapid transport of air masses influenced by CH4 sources in South Asia and East Asia. The observed isotopic ratio data suggest that CH4 sources in these areas have relatively low δ13C and δD signatures, implying biogenic sources. Latitudinal distributions of the annual average UT and LT CH4 mixing ratio intersect each other in the tropics; the mixing ratio value is lower in the UT than in the LT in the NH and the situation is reversed in the Southern Hemisphere (SH), due mainly to the NH air intrusion into the SH through the UT. Such intersection of the latitudinal distributions is observable in δD but not in δ13C, implying additional contribution of a reaction of CH4 with active chlorine in the marine boundary layer. δ13C and δD show low values in the NH and high values in the SH both in the UT and in the LT. We also observed an increase in the CH4 mixing ratio and decreases in δ13C and δD during 2007–2008 in the UT and LT over the Western Pacific, possibly due to enhanced biogenic emissions in the tropics and NH.

scholarly journals High Cloud Properties from Three Years of MODIS Terra and Aqua Collection-4 Data over the Tropics

2007 ◽  
Vol 46 (11) ◽  
pp. 1840-1856 ◽  
Author(s):  
Gang Hong ◽  
Ping Yang ◽  
Bo-Cai Gao ◽  
Bryan A. Baum ◽  
Yong X. Hu ◽  
...  
Keyword(s):  
Cloud Fraction ◽  
South Pacific Convergence Zone ◽  
Convergence Zone ◽  
Ice Clouds ◽  
High Cloud ◽  
Convective Clouds ◽  
Cloud Properties ◽  
Deep Convective Clouds ◽  
The Tropics ◽  
High Clouds

Abstract This study surveys the optical and microphysical properties of high (ice) clouds over the Tropics (30°S–30°N) over a 3-yr period from September 2002 through August 2005. The analyses are based on the gridded level-3 cloud products derived from the measurements acquired by the Moderate Resolution Imaging Spectroradiometer (MODIS) instruments aboard both the NASA Earth Observing System Terra and Aqua platforms. The present analysis is based on the MODIS collection-4 data products. The cloud products provide daily, weekly, and monthly mean cloud fraction, cloud optical thickness, cloud effective radius, cloud-top temperature, cloud-top pressure, and cloud effective emissivity, which is defined as the product of cloud emittance and cloud fraction. This study is focused on high-level ice clouds. The MODIS-derived high clouds are classified as cirriform and deep convective clouds using the International Satellite Cloud Climatology Project (ISCCP) classification scheme. Cirriform clouds make up more than 80% of the total high clouds, whereas deep convective clouds account for less than 20% of the total high clouds. High clouds are prevalent over the intertropical convergence zone (ITCZ), the South Pacific convergence zone (SPCZ), tropical Africa, the Indian Ocean, tropical America, and South America. Moreover, land–ocean, morning–afternoon, and summer–winter variations of high cloud properties are also observed.

Insights into Cloud-Top Height and Dynamics from the Seasonal Cycle of Cloud-Top Heights Observed by MISR in the West Pacific Region

2010 ◽  
Vol 67 (1) ◽  
pp. 248-261 ◽  
Author(s):  
Jung Hyo Chae ◽  
Steven C. Sherwood
Keyword(s):  
Seasonal Cycle ◽  
Environmental Stability ◽  
Weather Research And Forecasting ◽  
Change Scenario ◽  
Convective Clouds ◽  
Cloud Height ◽  
Deep Convective Clouds ◽  
Cloud Resolving Model ◽  
High Clouds ◽  
The Western Pacific

Abstract The connection between environmental stability and the height of tropical deep convective clouds is analyzed using stereo cloud height data from the Multiangle Imaging Spectroradiometer (MISR), focusing on the seasonal cycle of clouds over the western Pacific Ocean. Three peaks in cloud-top height representing low, mid-topped, and deep convective clouds are found as in previous studies. The optically thickest cloud heights are roughly 2 km higher on the summer side of the equator, where CAPE is higher, than on the winter side. Overall cloud height, however, is about the same on both sides of the equator, but ∼600 m higher in December–February (DJF) than in June–August (JJA). Because of variations in stratospheric upwelling, temperatures near the tropopause exhibit a significant seasonal cycle, mainly above 13 km. Using an ensemble of simulations by the Weather Research and Forecasting (WRF) cloud-resolving model and a simple overshooting parcel calculation, the authors show that the cloud height variation can be explained by that of near-tropopause stability changes, including influence from heights above 14 km, even though the cloud height peaks only near 12 km. This suggests that mixing above cloud top—not typically accounted for in simple models of convection—is important in setting the height of the laminar (anvil) high clouds that result. The MISR data indicate a seasonal variation in peak cloud-top temperature of ∼5 K, despite the recent proposal that cloud-top heights should track a fixed isotherm. That proposal must therefore be applied with caution to any climate-change scenario that may involve significant changes in stratospheric upwelling.

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