Atlantic Multi-decadal Oscillation Modulates the Relationship Between El Niño-Southern Oscillation and Fire Weather in Australia
Abstract. El Niño–Southern Oscillation (ENSO) is an important driver of fire weather in Australia. The correlation between ENSO and Australian fire weather has strengthened over the recent two decades. However, the causes for this change have not been well investigated. Here, using reanalysis datasets and numerical model simulations, we show that the Atlantic Multi-decadal Oscillation (AMO) could potentially modulate the ENSO-Australian fire weather relationship. The correlation between ENSO and Australia fire weather index (FWI) increases from 0.17 to 0.70 when AMO shifts from its negative phase to its positive phase. This strengthening effect can be explained by the atmospheric teleconnection mechanisms. Specifically, the positive AMO phase, manifested as a warming North and Tropical Atlantic, generates Rossby wave trains and results in high pressures over Australia, which increases local temperature and wind speed but decreases precipitation. This signal superimposes ENSO and thus serves to enhance the ENSO effect on Australian fire weather.
Guanyu Liu et al.
Status: final response (author comments only)
RC1: 'Comment on acp-2022-858', Anonymous Referee #2, 06 Apr 2023
- AC1: 'Reply on RC1', Prof Li, 02 May 2023
RC2: 'Comment on acp-2022-858', Anonymous Referee #5, 07 Apr 2023
- AC2: 'Reply on RC2', Prof Li, 02 May 2023
RC3: 'Comment on acp-2022-858', Anonymous Referee #4, 11 Apr 2023
- AC3: 'Reply on RC3', Prof Li, 02 May 2023
RC4: 'Comment on acp-2022-858', Anonymous Referee #1, 11 Apr 2023
- AC4: 'Reply on RC4', Prof Li, 02 May 2023
RC5: 'Comment on acp-2022-858', Anonymous Referee #6, 18 Apr 2023
- AC5: 'Reply on RC5', Prof Li, 02 May 2023
- AC7: 'Reply on RC5', Prof Li, 02 May 2023
RC6: 'Comment on acp-2022-858', Anonymous Referee #3, 26 Apr 2023
- AC6: 'Reply on RC6', Prof Li, 02 May 2023
Guanyu Liu et al.
Guanyu Liu et al.
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This study states that the ENSO-Australian fire relationship can be modulated by the phase changes of AMO. Specially, Atlantic warming may induce warmer temperature and less precipitation, which serves to enhance wildfires when combined with positive ENSO phase. This result is useful in understanding the recent shift in the ENSO-Australian fire relationship and in future wildfire projection in Australia. However, to further improve this manuscript, there are a few issues and questions that need to be addressed:
1. The authors mainly looked at the AMO effect on positive ENSO-Australian fire relationship, i.e., the modulation of Australian fire weather during El Nino conditions. Could they also examine La Nina conditions? Will responses of Australian fire weather also be strengthened during La Nina?
2. While it is plausible that AMO modulates the ENSO-Australian fire relationship, another major decadal climate variability, PDO, also shifted its phase around 2000. PDO may exert an even stronger impact on Australian weather. How could the authors exclude the effect of PDO?
3. The authors only used fire weather to represent fire activities. This may not be exactly equal to the actual fire counts or emissions. It is suggested to validate the correlation between ENSO and Australian fires using other proxies such as burned area, fire counts, etc.
4. Figure S8 did not give any statistical significance test of SST anomaly, which should be presented for clarity.