Mid-Tropospheric Cyclones (MTCs) are moist synoptic systems with middle tropospheric vorticity maxima and little or no signature in the lower and upper troposphere. Apart from a few case studies over South Asia, the occurrence of MTCs in other parts of the tropics has not been explored. Here, we present MTC statistics over the globe (50 N - 50 S) using 20 years of MERRA-2 reanalysis data and compare them with monsoon lows, depressions, and tropical cyclones (together referred to as lower troposphere cyclones; LTCs). Automatic cyclone center detection on the 600 hPa geopotential height field is used to detect synoptic cyclone centers. Based on vertical profiles of vorticity, the detected systems are classified as MTCs or LTCs. We find that synoptic mid-level moist vorticity maxima are not limited to South Asia and are found over most of the globe’s monsoonal regions. Apart from South Asia (Arabian sea, Bay of Bengal, and South China sea), MTCs are observed over the west and central Africa, eastern and western Pacific during the boreal summer. In the boreal winter, regions that support MTCs include northern Australia, the southern Indian Ocean, and South Africa. All these regions show monthly, as well as inter-annual variability in MTC and LTC activity. In particular, most regions show high MTC center density early in the monsoon and relatively high LTC activity during respective primary monsoon months. In both hemispheres, MTCs are more prevalent nearer to the equator and usually coincide with regions of cross-equatorial low-level monsoon flow. LTCs, on the other hand, are more common further polewards, usually within the monsoon trough itself. Finally, the global tropical probability distribution of the difference between middle and lower level vorticity versus the height of peak vorticity is bimodal; one peak corresponds to MTCs at about 600 hPa while the second 900 hPa corresponds to LTCs. Thus, tropical moist cyclonic systems naturally tend to reside in either the MTC or LTC category.
