Observed variability of intertropical convergence zone over 1998—2018
The intertropical convergence zone (ITCZ) accounts for more than 30% of the global precipitation and its variability has a great effect on the people living in the tropical area. It is the manifestation of the Hadley circulation, tropical dynamic and thermodynamic coupling and the air-sea interactio...
| Main Authors: | , , , , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
IOP Publishing
2020-01-01
|
| Series: | Environmental Research Letters |
| Subjects: | |
| Online Access: | https://doi.org/10.1088/1748-9326/aba033 |
| _version_ | 1797747850799480832 |
|---|---|
| author | Chunlei Liu Xiaoqing Liao Juliao Qiu Yazhu Yang Xiaoli Feng Richard P Allan Ning Cao Jingchao Long Jianjun Xu |
| author_facet | Chunlei Liu Xiaoqing Liao Juliao Qiu Yazhu Yang Xiaoli Feng Richard P Allan Ning Cao Jingchao Long Jianjun Xu |
| author_sort | Chunlei Liu |
| collection | DOAJ |
| description | The intertropical convergence zone (ITCZ) accounts for more than 30% of the global precipitation and its variability has a great effect on the people living in the tropical area. It is the manifestation of the Hadley circulation, tropical dynamic and thermodynamic coupling and the air-sea interaction. Therefore, it is essential to understand the changes and variability of the ITCZ, including its position and intensity. Using observed precipitation from GPCP and TRMM 3B43, as well as the ERA5 reanalysis data, we examine the ITCZ variations over the global and seven regions from 1998–2018. These data sets show consistent ITCZ climatology and inter-annual variability. Except over Atlantic and eastern Pacific where ITCZ stays in the northern hemisphere, the ITCZ crosses the equator after equinoxes over other sections. There is no overall significant shift of annual mean ITCZ position over the globe and seven regions, except over the America section where the GPCP data show a significant increase trend of 0.8° decade ^−1 and over the western Pacific section where ERA5 data show a significant decrease trend of −1.2° decade ^−1 . The ITCZ positions over the globe and Africa are related to both ENSO and NAO, while ITCZ position over eastern Pacific is significantly affected by ENSO and the Atlantic ITCZ is mainly related to NAO. Except for the western Pacific, all other sections are significantly related to local meridional surface temperature gradient, particularly over America, Atlantic and eastern Pacific. The meridional gradient variation of the vertically integrated moist static energy has generally good agreement with the shift of the intertropical convergence zone, particularly for the seasonal climatology over the Africa region. The relationship between ITCZ position and intensity shows complicated patterns, with positive correlation over the globe, but different correlations over different sections. The two observed data sets are more or less consistent, but ERA5 shows discrepancies over some sections. It is also found that the local meridional temperature gradient has more influences on the ITCZ positions than the global one. |
| first_indexed | 2024-03-12T15:56:33Z |
| format | Article |
| id | doaj.art-3fb8605133ff493dbccf59820e90bbe7 |
| institution | Directory Open Access Journal |
| issn | 1748-9326 |
| language | English |
| last_indexed | 2024-03-12T15:56:33Z |
| publishDate | 2020-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | Environmental Research Letters |
| spelling | doaj.art-3fb8605133ff493dbccf59820e90bbe72023-08-09T14:53:00ZengIOP PublishingEnvironmental Research Letters1748-93262020-01-01151010401110.1088/1748-9326/aba033Observed variability of intertropical convergence zone over 1998—2018Chunlei Liu0https://orcid.org/0000-0002-6663-452XXiaoqing Liao1Juliao Qiu2Yazhu Yang3Xiaoli Feng4Richard P Allan5https://orcid.org/0000-0003-0264-9447Ning Cao6Jingchao Long7Jianjun Xu8SIMM, Guangdong Ocean University , Zhanjiang, People’s Republic of China; Department of Meteorology, University of Reading , Reading RG6 6BB, United KingdomSIMM, Guangdong Ocean University , Zhanjiang, People’s Republic of ChinaSIMM, Guangdong Ocean University , Zhanjiang, People’s Republic of ChinaSIMM, Guangdong Ocean University , Zhanjiang, People’s Republic of ChinaSIMM, Guangdong Ocean University , Zhanjiang, People’s Republic of ChinaDepartment of Meteorology, University of Reading , Reading RG6 6BB, United Kingdom; National Centre for Earth Observation , Reading, United KingdomSIMM, Guangdong Ocean University , Zhanjiang, People’s Republic of ChinaSIMM, Guangdong Ocean University , Zhanjiang, People’s Republic of ChinaSIMM, Guangdong Ocean University , Zhanjiang, People’s Republic of ChinaThe intertropical convergence zone (ITCZ) accounts for more than 30% of the global precipitation and its variability has a great effect on the people living in the tropical area. It is the manifestation of the Hadley circulation, tropical dynamic and thermodynamic coupling and the air-sea interaction. Therefore, it is essential to understand the changes and variability of the ITCZ, including its position and intensity. Using observed precipitation from GPCP and TRMM 3B43, as well as the ERA5 reanalysis data, we examine the ITCZ variations over the global and seven regions from 1998–2018. These data sets show consistent ITCZ climatology and inter-annual variability. Except over Atlantic and eastern Pacific where ITCZ stays in the northern hemisphere, the ITCZ crosses the equator after equinoxes over other sections. There is no overall significant shift of annual mean ITCZ position over the globe and seven regions, except over the America section where the GPCP data show a significant increase trend of 0.8° decade ^−1 and over the western Pacific section where ERA5 data show a significant decrease trend of −1.2° decade ^−1 . The ITCZ positions over the globe and Africa are related to both ENSO and NAO, while ITCZ position over eastern Pacific is significantly affected by ENSO and the Atlantic ITCZ is mainly related to NAO. Except for the western Pacific, all other sections are significantly related to local meridional surface temperature gradient, particularly over America, Atlantic and eastern Pacific. The meridional gradient variation of the vertically integrated moist static energy has generally good agreement with the shift of the intertropical convergence zone, particularly for the seasonal climatology over the Africa region. The relationship between ITCZ position and intensity shows complicated patterns, with positive correlation over the globe, but different correlations over different sections. The two observed data sets are more or less consistent, but ERA5 shows discrepancies over some sections. It is also found that the local meridional temperature gradient has more influences on the ITCZ positions than the global one.https://doi.org/10.1088/1748-9326/aba033ITCZ position variabilityprecipitationmeridional temperature gradientmoist static energyobservations |
| spellingShingle | Chunlei Liu Xiaoqing Liao Juliao Qiu Yazhu Yang Xiaoli Feng Richard P Allan Ning Cao Jingchao Long Jianjun Xu Observed variability of intertropical convergence zone over 1998—2018 Environmental Research Letters ITCZ position variability precipitation meridional temperature gradient moist static energy observations |
| title | Observed variability of intertropical convergence zone over 1998—2018 |
| title_full | Observed variability of intertropical convergence zone over 1998—2018 |
| title_fullStr | Observed variability of intertropical convergence zone over 1998—2018 |
| title_full_unstemmed | Observed variability of intertropical convergence zone over 1998—2018 |
| title_short | Observed variability of intertropical convergence zone over 1998—2018 |
| title_sort | observed variability of intertropical convergence zone over 1998 2018 |
| topic | ITCZ position variability precipitation meridional temperature gradient moist static energy observations |
| url | https://doi.org/10.1088/1748-9326/aba033 |
| work_keys_str_mv | AT chunleiliu observedvariabilityofintertropicalconvergencezoneover19982018 AT xiaoqingliao observedvariabilityofintertropicalconvergencezoneover19982018 AT juliaoqiu observedvariabilityofintertropicalconvergencezoneover19982018 AT yazhuyang observedvariabilityofintertropicalconvergencezoneover19982018 AT xiaolifeng observedvariabilityofintertropicalconvergencezoneover19982018 AT richardpallan observedvariabilityofintertropicalconvergencezoneover19982018 AT ningcao observedvariabilityofintertropicalconvergencezoneover19982018 AT jingchaolong observedvariabilityofintertropicalconvergencezoneover19982018 AT jianjunxu observedvariabilityofintertropicalconvergencezoneover19982018 |