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

(Experimental NOAA/ESRL PSD and CIRES/U. of Colorado Forecast)

NEWC-LIM VERSION 3.0: New LIM, now with thermocline depth! Base period is also updated to 1982-2011. Improved forecast skill for multi-month forecast leads. Forecast of forecast skill (using pattern correlation throughout Tropics as skill measure) also included.

New forecasts running and updated daily, but archives of past forecasts/verifications before 2014 are not installed yet.

Forecasts and verifications:

Experimental forecasts of four key tropical fields, outgoing longwave radiation (OLR), 200 and 850 mb winds, and thermocline depth and sea surface temperature (SST); other variables may become available at a later date. Anomalies are averaged with a 5-day running mean and are relative to a 1982-2011 daily climatology (smoothed with a 31-day running mean). Forecast verification time is the central day of the forecast period.

Current initialization and a few selected forecast anomalies of OLR (W/m2), winds (m/s), 20 C isotherm depth (m, blue=positive), and SST (oC):

sstcl.maps

One key 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, wind, and SST anomalies into subseasonal variations including the MJO ("internal"), and longer term variations including ENSO ("coupled"). Hovmullers of the filtered datasets are updated daily; also available is an atlas of the C-LIM filtered data going back to 1982.

For a full description of the C-LIM methodology and a detailed analysis of the previous C-LIM version (v1.0), see:

  • Newman, M., P. D. Sardeshmukh, and C. Penland, 2009: How important is air-sea coupling in ENSO and MJO evolution? J. Climate, 22, 2958-2977.

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