A recently developed dropsonde atmospheric profiling system (High Definition Sounding System (HDSS)) manufactured by Yankee Environmental Systems (YES, Inc.) and a new generation of expendable digital dropsondes (XDD) will also be dropped from the NASA DC-8. These dropsondes will be used to supplement and confirm the detailed measurements made by DAWN. The combination of DAWN and dropsonde measurements will produce previously unobtained horizontal and vertical coverage. In addition, the dropsonde will be especially important in areas of opaque clouds where the DAWN will have difficulty making measurements.