天津地处华北平原的东北部,属大陆性气候。主要气候特征是,四季分明,春季多风,干旱少雨;夏季炎热,雨水集中;秋季气爽,冷暖适中;冬季寒冷,干燥少雪。平均无霜期为196~246d,年平均降水量为520~660mm,年日照时数为2 500~2 900h。农作物以玉米、小麦、棉花、水稻、大豆和小杂粮种植为主,种植面积38.67万hm2。我市自2002年以来降雨较少,大部分水田实行了稻改旱,稻改旱后基本种植作物为棉花,棉田基 Tianjin is located in the northeast of the North China Plain, a continental climate. The main climate is characterized by four seasons, spring windy, dry and little rain; summer is hot and rainwater is concentrated; autumn is cool, moderately warm and cold; winter is cold, dry and snow-less. The average frost-free period is 196 ~ 246d, the annual average rainfall is 520 ~ 660mm, the annual sunshine duration is 2 500 ~ 2 900h. Crops to corn, wheat, cotton, rice, soybeans and small grains mainly planted area of ​​386,700 hm2. The rainfall in our city has been relatively low since 2002, and most of the paddy fields have implemented paddy-to-drought irrigation. The basic crops for paddy cultivation are cotton, cotton base