BITMAP: Tracks of western disturbances transiting Pakistan and north India from various CMIP5 midHolocene experiments

• Main Authors: Hunt, Kieran, Turner, Andrew G., Shaffrey, Len C.
• Format: Dataset
• Language: English
• Published: Centre for Environmental Data Analysis (CEDA) 2019
• Subjects: Atmospheric sciences and Earth Observation Imagery; Arctic
• Online Access: https://dx.doi.org/10.5285/3a49f746dcdb4ff98e17919c84acbd20; https://catalogue.ceda.ac.uk/uuid/3a49f746dcdb4ff98e17919c84acbd20

This dataset contains tracks generated using a bespoke tracking algorithm developed within the BITMAP (Better understanding of Interregional Teleconnections for prediction in the Monsoon And Poles) project, identifying and linking upper-tropospheric vortices (described in Hunt et al, 2018, QJRMS - see linked documentation). The dataset was produced utilising data derived from from various simulation output for the WCRP Coupled Model Intercomparison Project, Phase 5 (CMIP5) 'mid-Holocene' experiment. Similar datasets were produced using various model output from the WRCP CMIP5 'Historical', 'RCP45' and 'RCP85' experiments and the ECMWF ERA-Interim reanalysis model output, also available within the parent dataset collection. The mid-Holocene period were designed to simulate the climate 6000 years ago, thus the representative date range for these data is circa 4025-4000 BC. Not all available CMIP5 mid-Holocene experiments were chosen for this dataset as the algorithm required 6-hourly output fields which were not available for all runs. Western disturbances (WDs) are upper-level vortices that can significantly impact the weather over Pakistan and north India. This is a catalogue of the tracks of WDs passing through the region (specifically 20-36.5N, 60-80E) on the 500 hPa layer. This differs from those tracks from the ECMWF Era-Interim data which were carried out on the 450-300 hPa layer. See linked documentation for details of the algorithms used. 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. For further details on the project itself see the linked Project record.