Statistical Distributions of Evaporation Ducts Over the South China Sea

Abstract

The database of evaporation ducts characteristics and meteorological parameters is constructed with about 0.2° spatial-temporal resolution in the South China Sea (SCS) between 2011 and 2020.By combining the National Centers for Environmental Prediction (NCEP) reanalysis data and the Naval Postgraduate School (NPS) model, the variation of modified refractivity M with height can be predicted. While analyzing the characteristics of the evaporation duct, five meteorological parameters need to be taken into account: the pressure and temperature at the surface, the relative humidity (RH) and temperature at 2 m above the ground and sea surface, and the wind speed data at 10 m above the surface. Meteorological datasets derived from NCEP are used as input to the algorithm; the Radio refractivity N is calculated with atmospheric temperature, pressure, and water vapor pressure. The modified refractivity M can be expressed as dM / dh=dN / dh + 0.157, where h is the height above the earth, and characteristics of the evaporation duct can be achieved. The evaporation duct height (EDH) will also be determined.We provided fifteen files include ‘Hourly Average EDH.xlsx’, ‘Monthly Average EDH.xlsx’, ‘Yearly Average EDH.xlsx’; ‘Hourly Average ASTD.xlsx’, ‘Monthly Average ASTD.xlsx’, ‘Yearly Average ASTD.xlsx’; ‘Hourly Average WS.xlsx’, ‘Monthly Average WS.xlsx’, ‘Yearly Average WS.xlsx’; ‘Hourly Average RH.xlsx’, ‘Monthly Average RH.xlsx’, ‘Yearly Average RH.xlsx’; ‘Hourly Average Meteorological Parameters In Typical Position.xlsx’, ‘Monthly Average Meteorological Parameters In Typical Position.xlsx’, and ‘Yearly Average Meteorological Parameters In Typical Position.xlsx’ in excel worksheets, users can open them with Microsoft office (office 2010 and later version).‘Hourly Average EDH.xlsx’, ‘Monthly Average EDH.xlsx’, and ‘Yearly Average EDH.xlsx’ files show the spatial and temporal statistical distribution of the average EDH as a function of hours, months, and years over the SCS (105° E ~125° E, 5° N~25° N), separately. The EDH in the SCS was divided in the grid form with 0.2° spatial resolution; the value at each grid point is derived from hourly meteorological parameters between 2011 and 2020 by NCEP databases and the NPS model. The database was constructed with hourly, monthly, and yearly statistical average values from 87672 hours of data at each grid point. And statistical results in different hours (from 0 o’clock to 23 o’clock in Beijing time, UTC +08:00), months (from Jan. to Dec.), and years (from 2011 to 2020) are classified with different sheets. The data size in each sheet is 101*101; the corresponding longitudes and latitudes are displayed in the first row and column.‘Hourly Average ASTD.xlsx’, ‘Monthly Average ASTD.xlsx’, and ‘Yearly Average ASTD.xlsx’ files show the spatial and temporal statistical distribution of the average air-sea temperature difference (ASTD) as a function of hours, months, and years over the SCS, separately. Consistent with the EDH statistical results, the data in each sheet shows corresponding ASTD in different longitudes and latitudes.Similarly, the wind speed (WS) dataset is recorded with ‘Hourly Average WS.xlsx’, ‘Monthly Average WS.xlsx’, and ‘Yearly Average WS.xlsx’ files.And the relative humidity (RH) dataset is recorded with ‘Hourly Average RH.xlsx’, ‘Monthly Average RH.xlsx’, and ‘Yearly Average RH.xlsx’ files.In addition, ‘Hourly Average Meteorological Parameters In Typical Position.xlsx’, ‘Monthly Average Meteorological Parameters In Typical Position.xlsx’, and ‘Yearly Average Meteorological Parameters In Typical Position.xlsx’ files show the average meteorological parameters (including sea surface temperature (SST), ASTD, WS, and RH) at five typical positions (including Land-sea interface, The coastal land, Taiwan Strait, Central SCS, Hainan Island) as a function of hours, months, and years, separately. The data of SST, ASTD, WS, and RH are classified with different sheets. The data size in each sheet is X*5, representing X statistical types (24 for hour, 12 for month, and 10 for year) and five typical positions. And the corresponding typical positions and statistical types are displayed in the first row and column.