Geodetic data records (GDRs) from the GEOSAT Exact Repeat Mission (ERM) from 07 March 1989 to 09 April 1989 (NODC Accession 8900145)

This accession contains one month of geodetic data records (GDRs) from the GEOSAT Exact Repeat Mission (ERM) for the time period of March 07, 1989 to April 09, 1989. Parameters include: time, orbit, latitude/longitude, and sea surface height. Corrections to the data include: sea level, wind and wave data, tides, dry and wet troposphere, ionosphere, height bias, altimeter crossover differences, altimeter sea surface measurement, and spacecraft orientation. These data were submitted by the U.S. Navy via National Oceanic Service.

The US Navy Geosat (Geodetic Satellite) radar altimeter mission lasted for nearly 5 years (March 1985 to January 1990) and collected approximately 750 million measurements of sea level, wave height, and wind speed over the global oceans. During the Geodetic Mission (March 1985 to September 1986), the satellite did not repeat its ground track for the duration of the mission. The orbit of the satellite was changed in early October 1986 to begin the Exact Repeat Mission (ERM) which lasted from November 8, 1986 until the satellite quit functioning in January 1990. During the ERM, the satellite repeated its ground track every 17 days. Data were initially processed by the Johns Hopkins University Applied Physics Laboratory in Laurel, MD in coordination with the NOAA/NOS Satellite Altimeter Group. Data products were transferred to the NOAA National Oceanographic Data Center (NODC) for distribution. Data products are archived at the NODC.

本数据集收录了1989年3月7日至1989年4月9日期间，GEOSAT精确重复任务（Exact Repeat Mission, ERM）产生的一个月大地测量数据记录（Geodetic Data Records, GDRs）。包含的参数包括：时间、轨道、经纬度以及海面高度。数据校正项包括：海平面校正、风浪数据校正、潮汐校正、干/湿对流层校正、电离层校正、高度偏差校正、高度计交叉轨迹差异校正、高度计海面测量校正以及航天器姿态校正。该数据集由美国海军通过国家海洋局（National Oceanic Service, NOS）提交。
美国海军Geosat（大地测量卫星）雷达高度计任务总时长近5年（1985年3月至1990年1月），在全球海洋范围内采集了约7.5亿次海平面、浪高及风速的测量数据。在大地测量任务阶段（1985年3月至1986年9月），卫星在轨运行期间未重复地面轨迹。1986年10月初，卫星轨道进行调整，正式启动精确重复任务（ERM），该任务自1986年11月8日启动，直至卫星于1990年1月停止运行。在ERM任务阶段，卫星每17天重复一次地面轨迹。数据最初由位于马里兰州劳雷尔市的约翰·霍普金斯大学应用物理实验室，与NOAA/NOS卫星高度计团队协作处理完成。后续数据产品移交至NOAA国家海洋数据中心（National Oceanographic Data Center, NODC）进行分发，目前所有数据产品均存档于该中心。