Impact of ERS-2 Scatterometer wind data on Global Analysis-Forecast system

The near surface scatterometer wind data from the European remote sensing satellite ERS-2 of European space agency(ESA) became available at NCMRWF on real time basis since February 1997. An attempt has been made to assimilate this data in the global data assimilation system(GDAS) operational at NCMRWF after proper quality control to study its impact on the analysis as well as on medium range weather forecast over the tropics. For this purpose the GDAS was run for 15 days (27 May to 10 June 1998). The impact has been examined through circulation characteristics and various objective scores. The study revealed that with proper quality control the scatterometer wind data can be assimilated in real time basis, resulting in an overall improvement in performance of the analysis-forecast system.

Inter-comparison of wind measurements in the atmospheric boundary layer and the lower troposphere with Aeolus and a ground-based coherent Doppler lidar network over China

After the successful launch of Aeolus, which is the first spaceborne wind lidar developed by the European Space Agency (ESA), on 22 August 2018, we deployed several ground-based coherent Doppler wind lidars (CDLs) to verify the wind observations from Aeolus. By the simultaneous wind measurements with CDLs at 17 stations over China, the Rayleigh-clear and Mie-cloudy horizontal-line-of-sight (HLOS) wind velocities from Aeolus in the atmospheric boundary layer and the lower troposphere are compared with those from CDLs. To ensure the quality of the measurement data from CDLs and Aeolus, strict quality controls are applied in this study. Overall, 52 simultaneous Mie-cloudy comparison pairs and 387 Rayleigh-clear comparison pairs from this campaign are acquired. All of the Aeolus-produced Level 2B (L2B) Mie-cloudy HLOS wind and Rayleigh-clear HLOS wind and CDL-produced HLOS wind are compared individually. For the inter-comparison result of Mie-cloudy HLOS wind and CDL-produced HLOS wind, the correlation coefficient, the standard deviation, the scaled mean absolute deviation (MAD) and the bias are 0.83, 3.15 m s−1, 2.64 m s−1 and −0.25 m s−1, respectively, while the y=ax slope, the y=ax+b slope and the y=ax+b intercept are 0.93, 0.92 and −0.33 m s−1. For the Rayleigh-clear HLOS wind, the correlation coefficient, the standard deviation, the scaled MAD and the bias are 0.62, 7.07 m s−1, 5.77 m s−1 and −1.15 m s−1, respectively, while the y=ax slope, the y=ax+b slope and the y=ax+b intercept are 1.00, 0.96 and −1.2 m s−1. It is found that the standard deviation, the scaled MAD and the bias on ascending tracks are lower than those on descending tracks. Moreover, to evaluate the accuracy of Aeolus HLOS wind measurements under different product baselines, the Aeolus L2B Mie-cloudy HLOS wind data and L2B Rayleigh-clear HLOS wind data under Baselines 07 and 08, Baselines 09 and 10, and Baseline 11 are compared against the CDL-retrieved HLOS wind data separately. From the comparison results, marked misfits between the wind data from Aeolus Baselines 07 and 08 and wind data from CDLs in the atmospheric boundary layer and the lower troposphere are found. With the continuous calibration and validation and product processor updates, the performances of Aeolus wind measurements under Baselines 09 and 10 and Baseline 11 are improved significantly. Considering the influence of turbulence and convection in the atmospheric boundary layers and the lower troposphere, higher values for the vertical velocity are common in this region. Hence, as a special note, the vertical velocity could impact the HLOS wind velocity retrieval from Aeolus.

Wave and sedimentation simulation of jetty construction to protect estuary, case study in Batang, Indonesia

To protect the estuary from sedimentation and waves need a jetty structure. This study discusses the alternative jetty design to be simulated for waves and sediments. The research was located in Batang Regency, Central Java Province. The study objective is to simulate wave and sediment for alternative estuary protection. Preliminary data are collected include topography and bathymetry, tidal observation data that include research area. The secondary data were wind data from BMKG of Semarang Station. The wind data used was each hour data for 16 years in the years 2004 to 2019. To simulate the wave and sediment, a software MIKE was used for the two alternative design. The first alternative using 2 jetties with 100 m length and the second alternative using two jetties with addition length for east side. Based on the sediment transport simulation result, the second alternative design put less 5 cm a year then the first alternative. The evaluation based on cost, time period construction, construction methods, According to the scoring, the first alternative design will be choose to the design and construction step.

Heat island study over Madras city and neighbourhood

Based on surface temperature, humidity and wind data collected from 77 points over a period of eight days in and around Madras using mobile surveys, the heat island characteristics at Madras have been assessed. The maximum heat island intensity is seen to be about 4°C. The humidity pattern apart from showing maritime influence also indicates a minimum over the heat pocket. The mixing height is found to be more over urban area than over rural area indicating lower pollution potential over the former due to the mixing over a larger depth than in the latter.

Sequential Least-Cost Path Sailing Model for Early 17th Century South China Sea: Digitally Navigating the Selden Map of China

During the 17th century, Southeast Asia was a bustling hub of maritime commerce. The Selden Map of China depicts some of the trade routes in the area and is drawn in a way which allows their sailing durations to be measured. This information is used in the development of a sequential least-cost path sailing model that utilizes deterministic timeseries wind data. The model can be used to simulate the optimized routes and durations between any points A and B in the South China Sea. With minor modifications, the method is applicable to other time periods and geographical settings.

Study of GPS Radiosonde observation system in Goa

Meteorological Radiosonde in the past used to apply navigation system to rout to determine the upper air pressure, temperature, humidity and the wind data through Radars. In this paper GPS Radiosonde test has been recently introduced in IMD is studied. The observations taken from M2K2 Radiosonde have been discussed. GPS Radiosonde obtains wind data as well.