Spotlight

Monsoon watch

Print edition : June 10, 2016

The monsoon at its peak over Kava village in Palakkad. A file picture. Photo: K.K. Mustafah

Fig. 1: Pre-monsoon growth of the variance of fluctuations in the weekly mean values of near-surface air temperature (T) (A) 21 days, (B) seven days; and (C) one day before the monsoon onset at the Eastern Ghats (EG). Composites are for the period 1958-2001; 700 hPa (mbar) winds (altitude about 3 km) are shown in blue lines. The boxes refer to reference grid points north Pakistan, or NP (blue) and EG (pink).

Fig. 2: Prediction of onset and withdrawal dates: case study year 2012. (a, b) Prediction of the onset date (OD); (c, d) withdrawal date (WD) of the monsoon in the EG. Time series from reference points (NCEP/NCAR data) for previous 14-year mean (black) and 2012 values for NP (blue) and the EG (red). Grey lines show time series from the NP and EG for the training period of previous 14 years. Saturation temperature Tsat and saturation humidity rhsat are marked by horizontal black solid lines.

Fig. 3: Monsoon OD and WD prediction based on T (green) and RH (orange) and measured (dark blue) (A) OD; (B) WD (NCEP/NCAR data). T: Temperature; RH: Relative humidity.

Fig. 4: Prediction of OD for 2016.

Researchers of PIK, Germany, claim that their novel method, using the Eastern Ghats and north Pakistan as the “tipping elements”, is better in predicting the onset and withdrawal of the Indian summer monsoon than the existing methods.
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