Saturday, May 2, 2015

Early note on April 2015 global

Most of the NCEP data for April global surface temperature is in. It was the coolest month so far in this warm year. As is common lately, it started cool, and only really warmed up to average (relative to current warmth). It was however, a bit warmer than last November, when GISS reported 0.63°C. March was &0.84°C. My guess for GISS in April is a bit over 0.7°C.


  1. GISS down with 0.12-0.14 should be a fair guess based on the reanalyses.
    However, My guess is more risky, I suggest 0.80 for GISS in April.
    My rationale for this somewhat crazy guess is that ERSST actually is up 0.04 in April. If we assume that Land temperatures are -0.20, SST +0.04, and give them the weight 1/3 and 2/3, the balanced global index should be down with about 0.04 compared to GISS March (0.84).

    1. Yes, that could be. We may forget that while NCEP estimates the air temperature near the surface, indices like GISS use SST. They generally move together, but not always. With that news from ERSST I would raise my guess considerably.

    2. Interesting Olof. Also plausible.

    3. FWIW, TempLS has done its first calc. 0.599, about 0.02 higher than last November. That's with all SST but not much land yet. March was 0,72. Plenty of change possible.

  2. So a TempLS value of 0.68 (down 0.04) is within reach. Good for my prediction.

    BTW, the ERSST value (+0.04 compared to March) is from this graph:
    (there is a lot of preliminary NCDC goodies in this directory)

    The reanalysis of SST show a very different picture. I digitized the one bottom down here:
    which suggested that April was 0.20 down compared with March.

    The ERSST monthly anomalies show a pronounced seasonal variation, following NH seasons. With an older base period the seasonality grows stronger, I assume
    The GISTEMP index has the oldest base period (1951-1980), hence it should be relatively more affected by ERSST seasonality.