An optimum initial manifold for improved skill and lead in long-range forecasting of monsoon variability

• Published in: Theoretical and applied climatology Vol. 144; no. 3-4; pp. 1161 - 1170
• Main Authors: Gouda, K. C., Joshi, S., Bhat, Nagaraj
• Format: Journal Article
• Language: English
• Published: Vienna Springer Vienna 01-05-2021; Springer; Springer Nature B.V
• Subjects: Aquatic Pollution; Atmospheric Protection/Air Quality Control/Air Pollution; Atmospheric Sciences; Climate science; Climatology; Earth and Environmental Science; Earth Sciences; Ensemble forecasting; Forecasting; General circulation models; Long-range forecasting; Manifolds; Methodology; Monsoon forecasting; Monsoons; Original Paper; Resolution; Waste Water Technology; Water Management; Water Pollution Control; Wind
• ISSN: 0177-798X; 1434-4483
• DOI: 10.1007/s00704-021-03589-x

Using an initial manifold approach, an ensemble forecast methodology is shown to simultaneously increase lead and realizable skill in long-range forecasting of monsoon over continental India. Initial manifold approach distinguishes the initial states that have coherence from a collection of unrelated states. In this work, an optimized and validated variable resolution general circulation model is being adopted for long-range forecasting of monsoon using the multi-lead ensemble methodology. In terms of realizable skill (as against potential) at resolution (~60km) and lead (2–5 months) considered here, the present method performs very well. The skill of the improved methodology is significant, capturing 9 of the 12 extreme years of monsoon during 1980–2003 in seasonal (June–August) scale. Eight-member ensemble-average hindcasts carried out for realizable skill with lead of 2 (for June) to 5 (for August) months and an optimum ensemble is presented.