Compiled historical daily temperature and precipitation data for selected 210 U.S. cities

Compiled historical daily temperature and precipitation data for selected 210 U.S. cities.
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Cities were selected based on lengths of existing climate records, which start at least earlier than 1900. However, cities may miss substantial amounts of data during their periods of record.
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Each file provides available historical daily maximum and minimum temperature and daily precipitation data for one U.S. city. File was named by the city's current active weather station ID (GHCN ID).
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Each city may include records from one or multiple stations. Listed latitude and longitude for each city are from the city's current active weather station.
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Daily maximum and minimum temperature and daily precipitation were acquired from Applied Climate Information System (ACIS), developed by the NOAA Northeast Regional Climate Center (NRCC).
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The historical observations from ACIS belong to Global Historical Climatological Network - daily (GHCN-D) datasets.
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The included stations were based on NRCC’s “ThreadEx” project, which combined daily temperature and precipitation extremes at 255 NOAA Local Climatological Locations, representing all large and medium size cities in U.S. (Owen et al. 2006).
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See included README file for more information.<br>

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Other datasets from the same project can be accessed at: https://kilthub.cmu.edu/projects/Use_of_historical_data_to_assess_regional_climate_change/61538<br>

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ACIS database for historical observations: http://scacis.rcc-acis.org/<br>

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Additionally, GHCN-D datasets can also be accessed at: https://www.ncei.noaa.gov/data/global-historical-climatology-network-daily/
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Station information for each city can be accessed at: http://threadex.rcc-acis.org/
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- 2022 January updated -
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1. Temperature and precipitation records for 2021 were added (using values from GHCN-D at: https://www.ncei.noaa.gov/data/global-historical-climatology-network-daily/).
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- 2022 September updated - 
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Note that this dataset will no longer be updated. Future updates may be provided at: YuchuanLai.com.
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- 2021 January updated -
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1. Temperature and precipitation records for 2020 were added (using values from GHCN-D at: ftp://ftp.ncdc.noaa.gov/pub/data/ghcn/daily/).
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- 2020 January updated -
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1. Temperature and precipitation records for 2019 were added (using values from GHCN-D at: ftp://ftp.ncdc.noaa.gov/pub/data/ghcn/daily/).
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2. *CITY_ID*.csv files were already filled the missing values (represented with NA) to make to continuous time series from start of record to the end of 2019. *CITY_ID*_fill.csv files from the older version were deleted.
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- 2019 June updated -
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1. Baltimore (USW00093721) data for 2018 was updated (previously 2018 data appeared to be NA). Original files for Baltimore were removed.
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2. The GHCN ID for Baltimore was updated to be the ID for Baltimore-Washington International AP. city_info file was updated accordingly.

本数据集汇编了精选的210座美国城市的历史逐日气温与降水数据。
城市遴选标准为现有气候记录时长，要求记录起始年份不早于1900年。不过部分城市在其记录周期内可能存在大量数据缺失情况。
每个文件对应一座美国城市的可用历史逐日最高气温、最低气温与降水数据，文件名采用该城市当前活跃气象站的编号（GHCN ID）命名。
单座城市的数据集可包含单个或多个气象站的观测记录，列表中给出的城市经纬度取自该城市当前活跃气象站的坐标。
逐日最高气温、最低气温及降水数据源自美国国家海洋和大气管理局（NOAA）东北区域气候中心（NRCC）开发的应用气候信息系统（ACIS）。
ACIS中的历史观测数据隶属于全球历史气候学网络逐日数据集（GHCN-D）。
本数据集涵盖的气象站源自NRCC的“ThreadEx”项目，该项目整合了255个美国NOAA地方气候站点的逐日气温与降水极值数据，覆盖美国所有大中型城市（Owen等，2006年）。
详细信息请参阅附带的README文件。

本项目的其他数据集可通过以下链接获取：https://kilthub.cmu.edu/projects/Use_of_historical_data_to_assess_regional_climate_change/61538

历史观测数据的ACIS数据库：http://scacis.rcc-acis.org/

此外，全球历史气候学网络逐日数据集（GHCN-D）亦可通过以下链接获取：https://www.ncei.noaa.gov/data/global-historical-climatology-network-daily/

各城市的气象站信息可通过以下链接获取：http://threadex.rcc-acis.org/

——2022年1月更新——
1. 新增2021年气温与降水记录（数据取自GHCN-D，来源链接：https://www.ncei.noaa.gov/data/global-historical-climatology-network-daily/）。

——2022年9月更新——
请注意，本数据集将不再更新，后续更新内容将发布于YuchuanLai.com。

——2021年1月更新——
1. 新增2020年气温与降水记录（数据取自GHCN-D，来源链接：ftp://ftp.ncdc.noaa.gov/pub/data/ghcn/daily/）。

——2020年1月更新——
1. 新增2019年气温与降水记录（数据取自GHCN-D，来源链接：ftp://ftp.ncdc.noaa.gov/pub/data/ghcn/daily/）。
2. 所有*CITY_ID*.csv文件已补全缺失值（以NA标识），以形成从记录起始至2019年末的连续时间序列，旧版本中的*CITY_ID*_fill.csv文件已被移除。

——2019年6月更新——
1. 更新了巴尔的摩市（USW00093721）2018年的观测数据（此前该年份数据显示为NA），原巴尔的摩市数据文件已被移除。
2. 巴尔的摩市的GHCN ID已更新为巴尔的摩-华盛顿国际机场气象站的编号，配套的city_info文件已同步更新。