在過去的研究中，全球暖化下的哈德里胞(Hadley Cell)變化在氣候模式以及再分析資料中相差不小。因此本研究使用最接近觀測以及最廣泛使用的再分析資料來源(ERA-Interim, ERA5, JRA-55, CFSR跟CFSRv2)，研究1979到2018年哈德里胞的邊界、寬度、強度的變化，並比較各筆資料中的哈德里胞季節變化、年際變化、以及長期變化趨勢。我們發現全球暖化下的哈德里胞有明顯擴張趨勢，但是其強度變化則在各筆資料沒有一致表現。根據前人的理想化哈德里胞理論，哈德里胞的擴張有可能為副熱帶地區的對流層高度跟副熱帶地區的大氣穩定度增加造成。
本研究也透過ERSST v5的海溫資料，來了解大範圍熱帶海洋變異對區域性的哈德里胞影響。從聖嬰現象(El Nino-Southern Oscillation)模態的迴歸圖來說，我們可以看到南美洲跟印度洋區域型哈德里胞減弱，以及中東太平洋區域型哈德里胞增強。我們也從全球暖化模態的迴歸圖發現，全球暖化下西太平洋、東北太平洋跟大西洋的區域型哈德里胞強度增強最為明顯。

In previous studies, the difference between the Hadley Cell (HC) trend between Global Climate Models and reanalysis datasets is significant; therefore, we will focus on the HC trend presented in the near observational data, the reanalysis data. Our study of the HC will be done using the most popular reanalysis atmospheric datasets (ERA-Interim, ERA5, JRA-55, CFSR and CFSRv2 reanalysis), and will be used to examine the long-term variability, seasonal cycle, interannual variability of HC extent, width, and intensity from 1979 to 2018. Our results show that the HC has a consistent expanding trend; however, this is not the case with the HC strength trend. The HC expansion is also found to be correlated with the increase of subtropical tropopause height and subtropical gross static stability.
This study also uses ERSST v5 SST data to understand how large-scale SST modes influence the local HC. From the El Nino-Southern Oscillation (ENSO) regression map, we found that HC shows a decrease in intensity at South America and Indian Ocean during warm phases of ENSO, while the local HC intensity of the central and eastern Pacific increases. We also found that the Global Warming mode shows a local HC intensification at the western Pacific, northeastern Pacific and Atlantic Ocean specifically.

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