中国地理科学 ›› 2017, Vol. 27 ›› Issue (5): 800-809.doi: 10.1007/s11769-017-0908-4

• 论文 • 上一篇    下一篇

Identifying Sky Conditions in Iran from MODIS Terra and Aqua Cloud Products

Khodakaram HATAMI BAHMANBEIGLOU, Saeed MOVAHEDI   

  1. Faculty of Geographical Sciences and Planning, University of Isfahan, Isfahan 81746-73441, Iran
  • 收稿日期:2017-01-13 修回日期:2017-05-04 出版日期:2017-10-27 发布日期:2017-09-07
  • 通讯作者: Saeed MOVAHEDI,E-mail:S.movahedi@geo.ui.ac.ir E-mail:S.movahedi@geo.ui.ac.ir
  • 基金资助:

    Under the auspices of Faculty of Geographical Science and Planning,University of Isfahan,Doctoral Climatology Project (No.168607/94)

Identifying Sky Conditions in Iran from MODIS Terra and Aqua Cloud Products

Khodakaram HATAMI BAHMANBEIGLOU, Saeed MOVAHEDI   

  1. Faculty of Geographical Sciences and Planning, University of Isfahan, Isfahan 81746-73441, Iran
  • Received:2017-01-13 Revised:2017-05-04 Online:2017-10-27 Published:2017-09-07
  • Contact: Saeed MOVAHEDI,E-mail:S.movahedi@geo.ui.ac.ir E-mail:S.movahedi@geo.ui.ac.ir
  • Supported by:

    Under the auspices of Faculty of Geographical Science and Planning,University of Isfahan,Doctoral Climatology Project (No.168607/94)

摘要:

Clouds can influence climate through many complex interactions within the hydrological cycle. Due to the important effects of cloud cover on climate, it is essential to study its variability over certain geographical areas. This study provides a spatial and temporal distribution of sky conditions, cloudy, partly cloudy, and clear days, in Iran. Cloud fraction parameters were calculated based on the cloud product (collection 6_L2) obtained from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensors on board the Terra (MOD06) and Aqua (MYD06) satellites. The cloud products were collected daily from January 1, 2003 to December 31, 2014 (12 years) with a spatial resolution of 5 km×5 km. First, the cloud fraction data were converted into a regular geographic coordinate network over Iran. Then, the estimations from both sensors were analyzed. Results revealed that the maximum annual frequency of cloudy days occurs along the southern shores of the Caspian Sea, while the minimum annual frequency occurs in southeast Iran. On average, the annual number of cloudy and clear-sky days was 88 and 256 d from MODIS Terra, as compared to 96 and 244 d from MODIS Aqua. Generally, cloudy and partly cloudy days decrease from north to south, and MODIS Aqua overestimates the cloudy and partly cloudy days compared to MODIS Terra.

关键词: cloud fraction, sky conditions, Moderate Resolution Imaging Spectroradiometer (MODIS), Terra satellite, Aqua satellite, Iran

Abstract:

Clouds can influence climate through many complex interactions within the hydrological cycle. Due to the important effects of cloud cover on climate, it is essential to study its variability over certain geographical areas. This study provides a spatial and temporal distribution of sky conditions, cloudy, partly cloudy, and clear days, in Iran. Cloud fraction parameters were calculated based on the cloud product (collection 6_L2) obtained from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensors on board the Terra (MOD06) and Aqua (MYD06) satellites. The cloud products were collected daily from January 1, 2003 to December 31, 2014 (12 years) with a spatial resolution of 5 km×5 km. First, the cloud fraction data were converted into a regular geographic coordinate network over Iran. Then, the estimations from both sensors were analyzed. Results revealed that the maximum annual frequency of cloudy days occurs along the southern shores of the Caspian Sea, while the minimum annual frequency occurs in southeast Iran. On average, the annual number of cloudy and clear-sky days was 88 and 256 d from MODIS Terra, as compared to 96 and 244 d from MODIS Aqua. Generally, cloudy and partly cloudy days decrease from north to south, and MODIS Aqua overestimates the cloudy and partly cloudy days compared to MODIS Terra.

Key words: cloud fraction, sky conditions, Moderate Resolution Imaging Spectroradiometer (MODIS), Terra satellite, Aqua satellite, Iran