I don't know what applied mathematics is for. If you are good at mathematical modeling or running numerical models, the field of atmospheric science is for you. The two most important tasks in atmospheric science: diagnostic analysis and weather forecast are based on numerical simulation. The Department of Atmospheric Science of Sun Yat-sen University lacks talents in this field. The situation in other schools is not clear. But at least, if I understand your major correctly, applied mathematics is in the field of atmospheric science.