| 摘要: | 雲與降水均在水文循環中扮演重要角色，然在十大雲種中，積雨雲對水文循環有更直接的影響，一旦持續發展形成降水後，則易為短延時之強降雨進而造成災害。前人研究中，已知在不同的降水形態下，雲的垂直結構及雲微物理均呈現不同的特性。因此本研究將嘗試以衛星觀測資料，來瞭解大氣深對流中之雲核心（DCC）結構，分別探討其雲的微物理性質與地面降水的關係，以及大氣熱力動力狀態。
本研究使用2014年6月~2016年5月之24個月全球CloudSat/CPR與日本JAXA GSMaP全球降水產品，將二者進行時空匹配後，發現全球有三大主要DCC好發區（東南亞地區（SEA）、非洲中部（AF）及亞馬遜盆地（（AZ）。研究結果指出DCC的發展高度與降雨率呈正相關，此外在對流層中，冰晶數量濃度（INC）、冰晶有效半徑（IRe）、相對溼度（RH）以及垂直上升氣流的垂直分佈顯示參數值越明顯時會有較大的降雨率，這表明這些雲微物理參數及相關大氣狀態能為直接或間接影響降雨率的敏感因素。
分析在對流層5-10 km間之中層高度DCC結構後發現，發生強降水的DCC，其IRe粒徑大於無降水的粒徑，且降雨率和IRe之間的顯著敏感高度區間在7至9 km。同時也發現，RH的變化也會影響粒徑和降雨率，並且於此高度區間，當較大雲滴粒徑（IRe>120 μm）的佔比大於50％時，發生強降雨率的機率為最高。於對流層13-14 km間之高度區間中，INC與降雨率則具有關連。於此高度中，當INC>450 L-1時容易出現大雨，而INC<400 L-1時則容易為弱降水甚至無降水情形。
更進一步分析全球三大好發區的資料後發現，DCC環境特性具有區域性環境特徵，其中SEA因海陸地形影響，水氣量豐沛，上升運動旺盛，因此DCC之環境特性會比其他兩區域更強。而SEA於對流層5-8 km高度其大冰晶粒徑分布比AF和AZ所佔比例較大；對流層高層中，冰晶濃度大小隨降雨率開始變化分界點於SEA為12 km，AF和AZ則為11 km。
;Both clouds and precipitation play an important role in the hydrological cycle. Among the ten major cloud species, Cumulonimbus (Cb) might have strong relationship between its internal structure and precipitation. In the development of Cbs, it is typically associated with the formation of severe precipitation. Therefore, it leads several natural disasters like flash flooding and lightening with intense rainfall in a short duration. From previous study, both the vertical structure and microphysical properties of cloud present different characteristics in the various types of precipitation. This study will focus on the use of satellite observation data to understand the relationship between the structure of deep convective core (DCC) and the microphysical properties of cloud and precipitation.
We analyzed 24 months global collocated CloudSat/ CPR, JAXA GSMaP precipitation data to identify three frequent DCC regions. The results show the developing height of DCC has positive correlation with the rain rate. The vertical distribution of the ice number concentration (INC), ice effective radius (IRe), relative humidity (RH) along with vertical updraft velocity in the troposphere reveal the larger values that are associated the heavier rain rate, which suggests these are important and sensitive factors to the severe rain rate.
In the mid-level of troposphere (5-10 km in altitudes), the representative cloud parameter is the IRe. The particles size of heavy precipitation is larger than non-precipitation. The biggest difference between the rain rate and IRe is the most significant in the altitudes between 7 and 9 km. At the same time, the change in RH affects the particle size and rain rate as well. At this height, the percentage of IRe > 120 μm is greater than 50 ％, and there is a higher probability of heavy rain rate occurrence; in the upper level is the INC. The height of 13-14 km is the key to discuss the INC and rain rate. When the INC > 450 L-1 is prone to heavy rain rate, while INC < 400 L-1 is prone to weak precipitation or non-precipitation. As a result, the vertical velocity, RH, convective height, IRe, INC and precipitation are known to be closely related to this study.
After further analysis of the data from the three DCC developing regions in the world, it was found that the environmental characteristics of DCC have regional environmental characteristics. Among them, SEA is affected by the shape of the sea and the land, water vapor is abundant, and the updraft is strong, therefore, the environmental characteristics of DCC will be stronger than the other two regions. SEA has a large IRe distribution ratio of AF and AZ in 5-8 km. In the upper troposphere, the INC begins to change with rain rate which is 12 km in SEA, and 11 km in AF and AZ. |
