Western disturbances (WDs) are upper-level vortices that can significantly impact the weather over Pakistan and north India. This collection contains a catalogue of the tracks of WDs passing through the region (specifically 20-36.5N, 60-80E) produced from various model outputs. This work was undertaken as part of the NERC funded BITMAP (Better understanding of Interregional Teleconnections for prediction in the Monsoon and Poles) project.

BITMAP was an Indo-UK-German project (NERC grant award: NE/P006795/1) to develop better understanding of processes linking the Arctic and Asian monsoon, leading to better prospects for prediction on short, seasonal and decadal scales in both regions. Recent work had suggested that the pole-to-equator temperature difference is an essential ingredient driving variations in the monsoon.

Tracks of these WDs were generated using a bespoke tracking algorithm within the project applied to data from the European Centre for Medium-Range Weather Forecasts' (ECMWF) ERA-Interim reanalysis data and model output from various experiments of the World Climate Research Programme's Coupled Model Intercomparison Project Phase 5 (WCRP CMIP5). The algorithm, described in Hunt et al, 2017, QJRMS (see linked documentation), identified and linked upper-tropospheric vortices from the data and are available within this dataset collection. Additional details of the CMIP5 tracking algorithm are available in the Hunt et al. paper 'Representation of western disturbances in CMIP5 models' paper (see linked documentation). The principal difference between the algorithm used for the ERA-Interim data and the CMIP5 data is the choice of pressure levels on which the algorithm was run: 500 hPa for the ERA-Interim data and 450-300 hPa layer for the CMIP5 data.