Our result indicates that the MSSD of the two progradational sequences (I and II) corresponds to azimuths of 10°–20° and 340°–350°, respectively, intuitively indicating two sequences derived from different provenance-transport systems. The Bozhong sag, a subbasin of the Bohai Bay Basin with two typical progradational sequences (I and II), provides a suitable example to analyze MSSD and test the new method. The circular format of the wind rose shows the direction the winds blew from and the length of each 'spoke' around the circle shows how often the wind blew from that direction. In accordance with similar principles of the rose diagram used in structural geology, we have developed an analytical method and a workflow for a new rose diagram of seismic-based progradational sequence angles to determine MSSD. located in the top right corner of each data map shows the general wind direction and speed for each sampling period. We have developed a more quantitative and practical way to determine the major sediment-supply direction (MSSD) using a new type of rose diagram based on seismic progradational sequence angles. To calculate the typical amount of time that the wind blows from a particular direction and certain speeds just multiply the respective frequency by the appropriate amount of time.A conventional method for identifying sediment-supply directions is to characterize the seismic progradational reflection configuration, which is based mainly on qualitative observation of numerous seismic profiles. The legend at the bottom gives additional information such as the unit (km/hr), the average wind speed for the overall hours (in this case 12.8 km/hr), and percentage of time that the winds are calm (0%), and the years and month and hours of data on which each rose was constructed. Please note the legend at the bottom of the wind rose that gives the speed categories and their associated colors. Similarly, on this spoke it can be calculated that winds blow from the southeast at speeds between 7.2 and 10.8 km/hr about 3% of the time, at speeds between 10.8 and 18 km/hr about 7% of the time, between 18 and 28 km/hr about 5% of the time. Examining winds from the southeast (the longest spoke) one can determine that approximately 1% of the time the wind blows from the southeast at speeds between 3.6 and 7.2 kilometer per hour. These wind roses also provide details on speeds from different directions. This also shows that the wind rarely blows from the northwest. This is quickly calculated by taking the sum of the frequencies of each of these directions (13+16+10=39%). In fact, the 3 spokes around the southeast direction (ESE, SE and SSE) comprise 39% of all hourly wind directions. This rose shows that the winds at Chennai during the period blow from the southeast much of the time. All wind roses shown here use 16 cardinal directions, Percentage of time that winds blow from a particular direction and at certain speed ranges. Each spoke is broken down into discrete frequency categories that show the The wind roses shown here contain additional information. It is the wind rose for Chennai, India based on three months of hourly wind data (all hours of the day). Each concentric circle represents a different frequency,Įmanating from zero at the center to increasing frequencies at the outer circles.Īn example is shown below. The length of each "spoke" around theĬircle is related to the frequency of time that the wind blows from a particular direction. Presented in a circular format, the wind rose shows the frequency of winds blowing FROM particular directions. A wind rose gives a very concise but information-laden view of how wind speed and direction are typically distributed at a particular location.