CHAPTER 1 UPPER-AIR OBSERVATIONS

CHAPTER 1 UPPER-AIR OBSERVATIONS INTRODUCTION In this chapter, we discuss the different types of upper-air observations in addition to the primary upper- air observation equipment used by the Navy and Marine Corps. We also discuss how to identify information in the various upper-air code forms. Finally, we discuss the TEMP and PILOT codes that are used to disseminate upper-air observation data and the records that are maintained for each observation. UPPER-AIR OBSERVATIONS LEARNING OBJECTIVES: Recognize the uses of upper-air observation data. Identify the different types of upper-air observations. Determine which types of upper-air observations are conducted by Navy and Marine Corps observers. Identify the publications that govern upper-air observations and observation codes. During an upper-air sounding, special instruments measure different atmospheric elements in the lower two layers of the atmosphere. These layers are the troposphere and the stratosphere (fig. l-l). A meteorological transmitter, known as a radiosonde, is attached to a balloon and is tracked by ground equipment. The radiosonde contains sensors that transmit pressure, temperature, and relative humidity data to a receiver as the balloon ascends into the atmosphere. Wind information can also be determined by tracking the balloon’s movement via radio signal or optically. The information is processed, encoded, and then transmitted over automated weather networks. Upper-air observations are often referred to as upper-air soundings. The National Weather Service, U.S. Air Force, and the U.S. Navy’s meteorological and oceanographic forecast centers run primary upper-air forecast programs twice a day based on data received from the 0000Z and 1200Z upper-air soundings. The computer programs can use data up to 12 hours old. All observations, regardless of the observation time, are 1-1 used if received within 12 hours after the observation. Additionally, all transmitted observations, even those not used in forecasting programs, are automatically entered in the upper-air climatic data base at the National Climatic Data Center in Asheville, North Carolina. This data is used extensively in atmospheric research. Locally, upper air observations provide an immediate vertical profile of the atmosphere and are invaluable as a forecast tool, particularly for severe weather and general aviation forecasts. NAVY/MARINE CORPS UPPER-AIR PROGRAMS Upper-air observations are conducted aboard many naval ships and at many naval and Marine Corps stations. Aircraft carriers (CVs) and most amphibious ships (LCC, LHA, LHD, LPHs) routinely conduct upper-air observations primarily for operational support. This support includes weather forecasts as well as refractivity forecasts. Some sites located on islands or in remote areas are designated Synoptic Upper-air Observation Sites. These activities routinely conduct u p p e r - a i r o b s e r v a t i o n s t o s u p p o r t W o r l d Meteorological Organization (WMO) data collection requirements, as well as operational commitments. Mobile Environmental Teams (MET) use portable equipment aboard ship and at remote shore sites to conduct upper-air observations in support of operational and research requirements. Marine Corps Meteorological Mobile Facility (MMF) members also use portable equipment and meteorological vans to conduct upper-air observations to support forces on temporary deployments. Normally, all upper-air observations from ships, designated Synoptic stations, and remote land locations are encoded and transmitted. Special observations conducted for training at shore stations may be encoded but are not usually transmitted. NOTE: In this chapter, we use altitude and height only by the strictest definition: height is the vertical measurement or approximation above the ground level (AGL); altitude is the vertical measurement or approximation above mean sea level (MSL). Most