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.

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 Tropical deep convective life cycle: Cb-anvil cloud microphysics from high-altitude aircraft observations

2014 ◽  
Vol 14 (23) ◽  
pp. 13223-13240 ◽  
Author(s):  
W. Frey ◽  
S. Borrmann ◽  
F. Fierli ◽  
R. Weigel ◽  
V. Mitev ◽  
...  
Keyword(s):  
Life Cycle ◽  
High Altitude ◽  
Potential Temperature ◽  
Cloud Microphysics ◽  
Mature Stage ◽  
Convective System ◽  
Ice Crystal ◽  
Convective Clouds ◽  
Tropical Tropopause ◽  
Deep Convective Clouds

Abstract. The case study presented here focuses on the life cycle of clouds in the anvil region of a tropical deep convective system. During the SCOUT-O3 campaign from Darwin, Northern Australia, the Hector storm system has been probed by the Geophysica high-altitude aircraft. Clouds were observed by in situ particle probes, a backscatter sonde, and a miniature lidar. Additionally, aerosol number concentrations have been measured. On 30 November 2005 a double flight took place and Hector was probed throughout its life cycle in its developing, mature, and dissipating stage. The two flights were four hours apart and focused on the anvil region of Hector in altitudes between 10.5 and 18.8 km (i.e. above 350 K potential temperature). Trajectory calculations, satellite imagery, and ozone measurements have been used to ensure that the same cloud air masses have been probed in both flights. The size distributions derived from the measurements show a change not only with increasing altitude but also with the evolution of Hector. Clearly different cloud to aerosol particle ratios as well as varying ice crystal morphology have been found for the different development stages of Hector, indicating different freezing mechanisms. The development phase exhibits the smallest ice particles (up to 300 μm) with a rather uniform morphology. This is indicative for rapid glaciation during Hector's development. Sizes of ice crystals are largest in the mature stage (larger than 1.6 mm) and even exceed those of some continental tropical deep convective clouds, also in their number concentrations. The backscatter properties and particle images show a change in ice crystal shape from the developing phase to rimed and aggregated particles in the mature and dissipating stages; the specific shape of particles in the developing phase cannot be distinguished from the measurements. Although optically thin, the clouds in the dissipating stage have a large vertical extent (roughly 6 km) and persist for at least 6 h. Thus, the anvils of these high-reaching deep convective clouds have a high potential for affecting the tropical tropopause layer by modifying the humidity and radiative budget, as well as for providing favourable conditions for subvisible cirrus formation. The involved processes may also influence the amount of water vapour that ultimately reaches the stratosphere in the tropics.

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 Comparing the impact of environmental conditions and microphysics on the forecast uncertainty of deep convective clouds and hail

2020 ◽  
Vol 20 (4) ◽  
pp. 2201-2219
Author(s):  
Constanze Wellmann ◽  
Andrew I. Barrett ◽  
Jill S. Johnson ◽  
Michael Kunz ◽  
Bernhard Vogel ◽  
...  
Keyword(s):  
Sensitivity Analysis ◽  
Environmental Conditions ◽  
Vertical Wind Shear ◽  
Environmental Parameters ◽  
Cloud Microphysics ◽  
Heating Rates ◽  
Dimensional Parameter ◽  
Convective Clouds ◽  
Deep Convective Clouds ◽  
The Impact

Abstract. Severe hailstorms have the potential to damage buildings and crops. However, important processes for the prediction of hailstorms are insufficiently represented in operational weather forecast models. Therefore, our goal is to identify model input parameters describing environmental conditions and cloud microphysics, such as the vertical wind shear and strength of ice multiplication, which lead to large uncertainties in the prediction of deep convective clouds and precipitation. We conduct a comprehensive sensitivity analysis simulating deep convective clouds in an idealized setup of a cloud-resolving model. We use statistical emulation and variance-based sensitivity analysis to enable a Monte Carlo sampling of the model outputs across the multi-dimensional parameter space. The results show that the model dynamical and microphysical properties are sensitive to both the environmental and microphysical uncertainties in the model. The microphysical parameters lead to larger uncertainties in the output of integrated hydrometeor mass contents and precipitation variables. In particular, the uncertainty in the fall velocities of graupel and hail account for more than 65 % of the variance of all considered precipitation variables and for 30 %–90 % of the variance of the integrated hydrometeor mass contents. In contrast, variations in the environmental parameters – the range of which is limited to represent model uncertainty – mainly affect the vertical profiles of the diabatic heating rates.

scholarly journals Why Was the August Rainfall Pattern in the East Asia–Pacific Ocean Region in 2016 Different from That in 1998 under a Similar Preceding El Niño Background?

2019 ◽  
Vol 32 (18) ◽  
pp. 5785-5797 ◽  
Author(s):  
Dong Chen ◽  
Ya Gao ◽  
Huijun Wang
Keyword(s):  
Pacific Ocean ◽  
El Niño ◽  
El Nino ◽  
Southern China ◽  
Western Pacific ◽  
Asia Pacific ◽  
Western Pacific Ocean ◽  
El Niño Event ◽  
Ocean Region ◽  
The Western Pacific

AbstractPrevious studies have noted that a strong El Niño event occurring in the preceding winter will result in westward stretching of the western North Pacific subtropical high (WPSH) in the following summer, causing anomalously high precipitation in the Yangtze–Huaihe River basin and anomalously low precipitation in southern China. The winters preceding the summers of 1998 and 2016 featured strong El Niño events, which, along with the El Niño event of 1982, represented the strongest El Niño events since 1950. Under these similar El Niño event backgrounds, the July precipitation anomaly in 2016 was similar to that in 1998, but the August precipitation anomalies in the two years featured opposite distributions. According to the atmospheric circulation analysis, we found that an anomalous ascending motion appeared over the Indian Ocean, while an anomalous descending motion appeared over the Pacific Ocean in August 1998. In addition, the WPSH stretched westward over southern China. However, the atmospheric circulation distribution in August 2016 was the opposite of that in 1998, and the WPSH was divided into eastern and western parts by the anomalous western Pacific cyclone. Further analysis showed that the number of tropical cyclones and typhoons over the western Pacific Ocean increased significantly in August 2016, and their activities were concentrated in the South China Sea (SCS)–southern China region and the western Pacific Ocean, resulting in the division of the WPSH. Therefore, the numbers, tracks, and strengths of tropical cyclones and typhoons were responsible for the differences in the anomalous precipitation distributions over the East Asia–Pacific Ocean region between August 2016 and August 1998.

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