The INCOMPASS field campaign combines airborne and ground measurements of the 2016 Indian monsoon, towards the ultimate goal of better predicting monsoon rainfall. The monsoon supplies the majority of water in South Asia, but forecasting from days to the season ahead is limited by large, rapidly developing errors in model parametrizations. The lack of detailed observations prevents thorough understanding of the monsoon circulation and its interaction with the land surface: a process governed by boundary‐layer and convective‐cloud dynamics. INCOMPASS used the UK Facility for Airborne Atmospheric Measurements (FAAM) BAe‐146 aircraft for the first project of this scale in India, to accrue almost 100 h of observations in June and July 2016. Flights from Lucknow in the northern plains sampled the dramatic contrast in surface and boundary‐layer structures between dry desert air in the west and the humid environment over the northern Bay of Bengal. These flights were repeated in pre‐monsoon and monsoon conditions. Flights from a second base at Bengaluru in southern India measured atmospheric contrasts from the Arabian Sea, over the Western Ghats mountains, to the rain shadow of southeast India and the south Bay of Bengal. Flight planning was aided by forecasts from bespoke 4 km convection‐permitting limited‐area models at the Met Office and India's NCMRWF. On the ground, INCOMPASS installed eddy‐covariance flux towers on a range of surface types, to provide detailed measurements of surface fluxes and their modulation by diurnal and seasonal cycles. These data will be used to better quantify the impacts of the atmosphere on the land surface, and vice versa. INCOMPASS also installed ground instrumentation supersites at Kanpur and Bhubaneswar. Here we motivate and describe the INCOMPASS field campaign. We use examples from two flights to illustrate contrasts in atmospheric structure, in particular the retreating mid‐level dry intrusion during the monsoon onset.

In recent years, the upper air radiosounding system based on Global Positioning System (GPS) is used as an effective method. GPS receiving device in a Radiosonde improves observation accuracy, allowing simplification of ground equipment. To get improved quality of upper air data, ten stations have been upgraded with new upper air systems based on GPS. This paper describes the upper air radiosounding system that adopts the GPS. After the introduction of GPS Radiosonde in the network at 10 places, data quality has improved substantially at these stations, which has been validated by National Centre for Medium Range Weather Forecasting (NCMRWF) and European Centre for Medium-Range Weather Forecasts (ECMWF). In all cases the quality change has been remarkable and as a result black list tag is removed by ECMWF for the Indian GPS stations.

This paper describes the carbon humidity sensors manufactured in IMD using the material available in the Indian market. These are used in the IMD MK-IV radiosondes for taking routine upper air observation in the network.

India Meteorological Department (IMD), the National Meteorological / Hydrological system (NMHS) of India, has established GUAN standard radiosounding systems at 6 stations at its regional head quarters namely New Delhi, Mumbai, Kolkata, Chennai, Nagpur and Guwahati using high quality radiosounding system during August 2015. These stations have been equipped with M/s GRAW radiosondes, Germany make,  high quality GPS based radiosounding system model No GS-E along with DFM-09 radiosondes. Based on their performance of one year, IMD requested GCOS secretariat through Secretary General,  WMO, for inclusion of these station into GUAN network. IMD’s claim was discussed and approved by Atmospheric Observation Panel on Climate (AOPC-22), Exeter, UK, 27-31st March 2017. Since then, the performance has been closely monitored and found that these stations are fully compliant for the commitments to be made by the WMO Member for inclusion of a radiosounding station into the GUAN network. All the 6 stations have achieved minimum observational requirements like Nos. of sounding in a month, soundings observed beyond minimum requirement of 100 hPa level, and in most of the cases approach up to the target requirement of 5 hPa level.  The RMS departures in case of geo-potential height, observed temperatures and wind vectors have been found well within the minimum requirements (MRQs) and very near to the target requirements (TRQs)-which establishes the accuracies of observed data. The biases observed in monthly climatological averages are observed within the MRQs and approaching to the TRQs. These stations actually fulfilled the essential minimum requirements of radiosounding observations for a GUAN standard radiosounding station, with respect to all the parameters of observation, and very closely approaching the target requirements of GUAN standard radiosounding observatories continuously. The network has sustained without a break since the establishment, performing well meeting all the standards, and committed for continuation.

No abstract