Weekly Forecasts of Tropical Convection and SST using a Coupled Linear Inverse Model (C-LIM)

(Experimental NOAA/ESRL PSD and CIRES/CDC Forecast)

NEWC-LIM VERSION 1.1: updated SST dataset and more recent forecast initialization.

Forecasts:

Experimental forecasts of two key tropical fields, outgoing longwave radiation (OLR) and sea surface temperature (SST); other variables may be available soon. Anomalies are weekly averaged and relative to a 1982-2007 daily climatology (smoothed with a 31-day running mean). Forecast verification time is the central day of the forecast week.

One extra benefit of the C-LIM is that the eigenvectors of its dynamical evolution operator separate into two distinct, but nonorthogonal, subspaces: one governing the nearly uncoupled subseasonal dynamics, and the other governing the strongly coupled longer term dynamics. This results in a dynamically-based filter that, unlike bandpass or EOF-based filtering, can distinguish between variability having similar spatial structures but very different time scales due to differences between coupled air-sea and internal atmospheric dynamics. We project the tropical data onto these two subspaces, producing a real-time clean split of OLR and SST anomalies into subseasonal variations including the MJO ("internal"), and longer term variations including ENSO ("coupled"). Hovmullers of the two filtered datasets are updated daily; also available is an atlas of the C-LIM filtered data going back to 1982.

For a detailed description of the C-LIM, see:

  • Newman, M., P. D. Sardeshmukh, and C. Penland, 2009: How important is air-sea coupling in ENSO and MJO evolution? J. Climate, in press.

    Standard disclaimer: these forecasts are experimental. NOAA/PSD and CIRES/CDC are not responsible for any loss occasioned by the use of these forecasts.