Comparison of Satellite Cloud Image and Radar of Precipitation Process on July 31st,2007

Based on the data of satellite cloud image and Doppler radar,the rainstorm process from July 31st,2007 to August 1st,2007 in Liaoning was analyzed.The precipitation in Fushun and Haicheng was more than 100 mm,and 6 h precipitation in Fushun and Dandong was more than 50 mm.Through the analysis of strong precipitation period,the structure of clouds had a little decline from the stage of development to maturity.The gray value and gradient degree around were both larger in the center of heavy precipitation.

High Performance of Imaging Extraction for Infrared Satellite Cloud Image

The isotherm is an important feature of infrared satellite cloud images (ISCI), which can directly reveal substantial information of cloud systems. The isotherm extraction of ISCI can remove the redundant information and therefore helps to compress the information of ISCI. In this paper, an isotherm extraction method is presented. The main aggregate of clouds can be segmented based on mathematical morphology. T algorithm and IP algorithm are then applied to extract the isotherms from the main aggregate of clouds. A concrete example for the extraction of isotherm based on IBM SP2 is described. The result shows that this is a high efficient algorithm. It can be used in feature extractions of infrared images for weather forecasts.

Computer Identification of Multispectral Satellite Cloud Imagery

A dynamic clustering method based on multispectral satellite imagery to identify the different features is described. The channel combinations selected are for the different purposes in classification. Several cases are presented using the polar-orbiting satellite imageries.

A Method of Identifying Thunderstorm Clouds in Satellite Cloud Image Based on Clustering

In this paper,the clustering analysis is applied to the satellite image segmentation,and a cloud-based thunderstorm cloud recognition method is proposed in combination with the strong cloud computing power.The method firstly adopts the fuzzy C-means clustering(FCM)to obtain the satellite cloud image segmentation.Secondly,in the cloud image,we dispose the‘high-density connected’pixels in the same cloud clusters and the‘low-density connected’pixels in different cloud clusters.Therefore,we apply the DBSCAN algorithm to the cloud image obtained in the first step to realize cloud cluster knowledge.Finally,using the method of spectral threshold recognition and texture feature recognition in the steps of cloud clusters,thunderstorm cloud clusters are quickly and accurately identified.The experimental results show that cluster analysis has high research and application value in the segmentation processing of meteorological satellite cloud images.

Comparison of Satellite and Ship Observations for Total Cloud Amount

The data series of monthly clouldiness over global ocean from COADS was compared with that of from satellite Nimbus-7 during April 1979 to March 1985. The correspondence between them is good. Both the two methods of observation can provide useful information of the distribution of cloudiness and the two data sets can be mutually complementary.

Transport Layer Optimization for Cloud Computing Applications via Satellite： TCP Noordwijk＋

Cloud computing can significantly improve efficiency in Internet utilization and data management.Several cloud applications(file sharing,backup,data up/download etc.) imply transfers of large amount of data without real-time requirements.In several use-cases cloud-computing solutions reduce operational costs and guarantee target QoS.These solutions become critical when satellite systems are utilized,since resources are limited,network latency is huge and bandwidth costs are high.Using satellite capacity for cloud-computing bulk traffic,keeping acceptable performance of interactive applications,is very important and can limit the connectivity costs.This goal can be achieved installing in the Set Top Box(STB) a proxy agent,to differentiate traffic and assign bandwidth according to priority,leaving spare capacity to bulk cloud computing traffic.This aim is typically reached using a specific QoS architecture,adding functional blocks at network or lower layers.We propose to manage such a process at transport layer only.The endpoint proxy implements a new transport protocol called TCP Noordwijk+,introducing a flow control differentiation capability.The proxy includes TPCN+ which efficiently transfers low-priority bulk data and handles interactive data,keeping a high degree of friendliness.The outcomes of Ns-2simulations confirm applicability and good performance of the proposed solution.

Man-Computer Interactive Method on Cloud Classification Based on Bispectral Satellite Imagery

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RESEARCH ON SATELLITE IMAGE PROCESSING AND RECOGNITION WITH PARALLEL ALGORITHM

Using the method of mathematical morphology,this paper fulfills filtration,segmentation and extraction of morphological features of the satellite cloud image.It also gives out the relative algorithms,which is realized by parallel C programming based on Transputer networks.It has been successfully used to process the typhoon and the low tornado cloud image.And it will be used in weather forecast.

Estimation of Cloud Motion Using Cross-Correlation

This paper describes the estimation of cloud motion using lag cross-correlation. In order to compute the lag cross correlation, the Bayes Decision method is used first to identify cloud and surface of earth. Then cloud motion vectors are retrieved at a subset of points through multiple applications of a cross-correlation analysis. An objective analysis is used to define displacement at every satellite pixel throughout the domain and smooth the local inconsistencies. Cloud motions are then produced with a backward trajectory technique by using these displacement vectors.

ANALYSIS OF AMBIENT FIELDS AND SATELLITE IMAGERY CHARACTERISTICS OF EFFECT OF BAY OF BENGAL STORMS ON LOW- LATITUDE PLATEAU

Based on the composite analysis method, 12 rainstorms triggered by Bay of Bengal storms (shortened as B-storms hereafter) across the whole province of Yunnan were studied, and some interesting results of rain and circulation characteristics influenced by the storms were obtained for low-latitude plateau. Usually, when a rainstorm weather occurs in low-latitude plateau, the B-storm center locates in the central, east or north parts of the Bay of Bengal. At the same time, the subtropical high ridge moves to 15°N– 20°N and the west ridge point moves to the Indo-china Peninsula from the South China Sea and the low-latitude plateau is controlled by southwest air streams coming from the front of the trough and the periphery of the subtropical high. The southwest low-level jet stream from the east side of the bay storm has great effect on heavy rains. On the one hand, the southwest low-level jet stream is playing the role of transporting water vapor and energy. On the other hand, the southwest low-level jet stream is helpful to keep essential dynamical condition. From the analysis of the satellite cloud imagery, it is found that mesoscale convection cloud clusters will keep growing and moving into the low-latitude plateau to cause heavy rains when a storm forms in the Bay of Bengal.

Analysis on A Heavy Rain to Rainstorm Weather Process in Liaoning Province

By using the synoptic chart,the physical quantity field,the satellite cloud image and the meteorological elements in the single station,a typical heavy rain to rainstorm weather process which occurred in Liaoning during August 18-20 in 2009 was comprehensively analyzed.The results showed that this process was a weather process which was affected by the upper trough and the subtropical high.Baikal Lake split cold air and Hetao cold air shifted eastward and formed the vortex.The subtropical high extended westward,lifted northward,and the warm wet airflow in the edge cut in.The low-altitude jet stream accelerated the transportation of water vapor,and several active meso-scale convective cloud clusters which appeared in 588 line periphery in the right side of high-altitude jet stream outlet gradually merged with the westerlies system.It caused that the strong mixed precipitation process occurred.

Diagnosis of An Infrequent Regional Hail Weather Course in Gansu

Based on routine weather charts, numerical predication products and satellite cloud images, the causes of an infrequent regional hail weather process occurred in east of Gansu on Aug. 2, 2006 were diagnosed and analyzed. The results showed that the hail weather process occurred at the abnormal large-scale circulation leading the system to west. When the cold trough, which was separated by the north cold vortex, moved southward through Hetao and then intersected with 300 hPa jet stream and the surface cold front, that led to the strong convection. There were strong upward motion and unstable stratification in hail area, three MCS in satellite cloud, and a character of formed arch shape echo on radar echo charts.

Local Spiral Curves Simulating Based on Hough Transformation and Center Auto-Locating of Developing Typhoon

In the developing phase of typhoon formation, the spiral belt partly emerges in satellite cloud images. This research starts from images and moves on to graphics and then to representation and recognition. Following this route, local spiral cloud belt is segmented from the raw images using image segmentation, the spiral information is extracted using mathematic morphology, and local spiral curves are detected using Hough transformation. The problem of center locating of developing typhoon has finally been solved through a search algorithm of spiral curve. For No. 99082008 cloud image, the result produced by the algorithm in this paper is at 122..3 degree west longitude, 117.5 degree north latitude. The real typhoon center location was at 122.4 degree west longitude, 18 degree north latitude.

Analysis of the Rainstorm Falling Zone in Guangxi during Influence Period of the 0906 Typhoon "Molave"

[ Objective] The research aimed to analyze rainstorm falling zone in Guangxi during influence period of the 0906 typhoon ＂ Molave＂. [ Method] For the heavy precipitation falling zone in southern and central parts of Guangxi after 0906 typhoon ＂ Molave＂ landed, 500 hPa circula- tion, physical quantity field, satellite cloud chart and terrain effect were analyzed. [ Result] 500 hPa subtropical high caused asymmetry of the ＂Me- lave＂ circulation, playing a key role for the strong precipitation falling zone in Guangxi. Physical quantity field analysis pointed out that after ＂ Me- lave＂ landed, water vapor convergence center was in southeast Guangxi, providing adequate moisture condition for the heavy precipitation in south- ern and central parts of Guangxi. The maximum positive vorticity center appeared at the middle and low layers in southern and central parts of Guangxi for a long time. At 200 hPa, there was a maximum divergence center. At 700 hPa, there was a maximum convergence center. High-level divergence and low-level convergence created conditions for heavy precipitation in the region. From satellite cloud chart, the heavy precipitation fall- ing zone related to asymmetric structure of the ~ Molave＂. In addition, uplifting effect of the terrain was conducive to occurrence of the large precipi- tation. [ Conclusion] The research provided reference for reduction and prevention of this kind of heavy precipitation.

Study on Causes of a Local Heavy Rainstorm Process in Shandong Province

Based on conventional meteorological observation data, NECP 1°×1° reanalysis data, precipitation data from automatic weather stations on the ground, FY- 2E satellite cloud images, and so forth, the circulation background, formation mechanism and features of a satellite cloud image of a local heavy rainstorm process in Shandong Province during August 8-9 in 2010 were analyzed. The results showed that the slow eastward movement of short-wave trough at middle and high latitudes, the stable maintenance of the subtropical high and ground cyclone, and the strong development of extra low-level southeast flow were large-scale circulation back- grounds of occurrence of the rainstorm; the rainstorm generated under the effects of mesoscale echo clusters or echo belts and mesoscale convective cloud clusters; precipitation mainly happened in periods when convective cloud clusters generated, developed and matured, and short-time heavy precipitation mainly appeared in the west, southwest and south of convective cloud clusters; extra low-level southeast flow was very conducive to the occurrence of short-time heavy precipitation; mesoscale convective systems rose in the whole troposphere, and the constant enhancement of low-level θse frontal zone provided favorable unstable energy for the occurrence of convective heavy rainfall.

Aerosol-cloud-precipitation interactions:A challenging problem in regional environment and climate research

Aerosols affect clouds in two broad ways： （i） presence of more number of aerosols leads to formation of more smaller droplets, and reduces coalescence, resulting in brighter clouds that reflect more solar energy back to space, hence they contribute to cooling of the Earth＇s surface and （ii） numerous smaller cloud droplets tend to reduce precipitation and change the extent of cloud cover and increase cloud lifetime and albedo. One of our recent studies on aerosols over the lndo-Gangetic Plains （IGP） relative to the pristine oceans to the south of Indian Ocean showed that highly absorbing aerosols could potentially lead to the revival of active condition preceded by long break. The absorption of solar radiation by aerosols such as black carbon and desert dust produces surface cooling and local stabilization of lower atmosphere. This stability effect is overcome by the enhanced moisture convergence due to the meridional gradient of aerosol-induced heating. In some other studies, we showed association between cloud thickness and cloud to sub-cloud ratio （SCR）, aerosol variability （in terms of aerosol optical depth and aerosol index） and monsoon precipitation and climate over regional scale. This paper provides an overview of some salient results that have been obtained from the studies conducted, using the ground- and space-based active and passive remote sensing techniques, at the Indian Institute of Tropical Meteorology （IITM）, Pune, India in the recent decade.