Characteristics of monsoon inversions over the Arabian Sea observed by satellite sounder and reanalysis data sets

• Published in: Atmospheric chemistry and physics Vol. 16; no. 7; pp. 4497 - 4509
• Main Authors: Dwivedi, Sanjeev, Narayanan, M. S, Venkat Ratnam, M, Narayana Rao, D
• Format: Journal Article
• Language: English
• Published: Katlenburg-Lindau Copernicus GmbH 12.04.2016; Copernicus Publications
• Subjects: Accuracy; Atmospheric data; Atmospheric Infrared Sounder; Atmospheric sounding; Data; Datasets; Global positioning systems; GPS; Humidity; Infrared instruments; Infrared interferometers; Inversions; Measuring instruments; Monsoon rainfall; Monsoons; NOAA satellites; Parameters; Radio occultation; Rain; Rainfall; Refractive index; Refractivity; Remote sensing; Satellite constellations; Satellite navigation systems; Satellite observation; Satellites; Southwest monsoon; Spaceborne remote sensing; Summer monsoon; Temperature; Temperature differences; Temperature gradients; Water temperature; Water vapor; Water vapour; Wind; Indian Ocean; Arabian Sea; India
• ISSN: 1680-7324; 1680-7316; 1680-7324
• DOI: 10.5194/acp-16-4497-2016

Monsoon inversion (MI) over the Arabian Sea (AS) is one of the important characteristics associated with the monsoon activity over Indian region during summer monsoon season. In the present study, we have used 5 years (2009–2013) of temperature and water vapour measurement data obtained from satellite sounder instrument, an Infrared Atmospheric Sounding Interferometer (IASI) onboard MetOp satellite, in addition to ERA-Interim data, to study their characteristics. The lower atmospheric data over the AS have been examined first to identify the areas where MIs are predominant and occur with higher strength. Based on this information, a detailed study has been made to investigate their characteristics separately in the eastern AS (EAS) and western AS (WAS) to examine their contrasting features. The initiation and dissipation times of MIs, their percentage occurrence, strength, etc., has been examined using the huge database. The relation with monsoon activity (rainfall) over Indian region during normal and poor monsoon years is also studied. WAS ΔT values are  ∼  2 K less than those over the EAS, ΔT being the temperature difference between 950 and 850 hPa. A much larger contrast between the WAS and EAS in ΔT is noticed in ERA-Interim data set vis-à-vis those observed by satellites. The possibility of detecting MI from another parameter, refractivity N, obtained directly from another satellite constellation of GPS Radio Occultation (RO) (COSMIC), has also been examined. MI detected from IASI and Atmospheric Infrared Sounder (AIRS) onboard the NOAA satellite have been compared to see how far the two data sets can be combined to study the MI characteristics. We suggest MI could also be included as one of the semipermanent features of southwest monsoon along with the presently accepted six parameters.