Abstract
Abstract. Subseasonal forecasts of opportunity (SFOs) for precipitation over
southwest Asia during January–March at lead times of 3–6 weeks are
identified using elevated expected forecast skill from a linear inverse
model (LIM), an empirical dynamical model that uses statistical
relationships to infer the predictable dynamics of a system. The expected
forecast skill from this LIM, which is based on the atmospheric circulation,
tropical outgoing longwave radiation, and sea surface temperatures, captures
the predictability associated with many relevant signals as opposed to just
one. Two modes of variability, El Niño–Southern Oscillation (ENSO) and
the Madden–Julian Oscillation (MJO), which themselves are predictable
because of their slow variations, are related to southwest Asia
precipitation SFOs. Strong El Niño events, as observed in 1983, 1998,
and 2016, significantly increase the likelihood by up to 3-fold of an SFO 3–4 and 5–6 weeks in advance. Strong La Niña events, as observed in 1989, 1999, 2000, also significantly increase the likelihood of an SFO at those same lead times. High-amplitude MJO events in phases 2–4 and 6–8 of greater than one standardized departure also significantly increase the
likelihood of an SFO 3–4 weeks in advance. Predictable atmospheric
circulation patterns preceding anomalously wet periods indicate a role for
enhanced tropical convection in the South Pacific convergence zone (SPCZ)
region, while suppressed convection is observed preceding predictable dry
periods. Anomalous heating in this region is found to distinguish wet and
dry periods during both El Niño and La Niña conditions, although the atmospheric circulation response to the heating differs between each ENSO phase.
Funder
United States Agency for International Development
Reference59 articles.
1. Agrawala, S., M. Barlow, H. Cullen, and Lyon, B.: The drought and humanitarian crisis in central and southwest Asia: A climate perspective, IRI Special Rep. 01–11, 24 pp., https://doi.org/10.7916/D8NZ8FHQ, 2001.
2. Albers, J. R. and Newman, M.: A priori identification of skillful
extratropical subseasonal forecasts, Geophys. Res. Lett., 46, 12527–12536,
https://doi.org/10.1029/2019GL085270, 2019.
3. Albers, J. R. and Newman, M.: Subseasonal predictability of the North
Atlantic Oscillation, Environ. Res. Lett., 16, 044024, https://doi.org/10.1088/1748-9326/abe781, 2021.
4. Albers, J. R., Newman, M., Hoell, A., Breeden, M. L., Wang, Y., and Lou, J.:
The February 2021 Cold Air Outbreak in the United States: a Subseasonal
Forecast of Opportunity, B. Am. Meteorol. Soc., https://doi.org/10.1175/BAMS-D-21-0266.1, online first, 2022.
5. Barlow, M., Cullen, H., and Lyon, B.: Drought in central and southwest Asia:
La Niña, the warm pool, and Indian Ocean precipitation, J. Climate, 15,
697–700, https://doi.org/10.1175/1520-0442(2002)015<0697:DICASA>2.0.CO;2, 2002.
Cited by
4 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献