1. Arctic weather in 1880-81

    06:05

    from Philip Brohan Added 58 0 0

    Near surface winds (vectors), pressure anomalies (contours, solid for low pressure, dashed for high), air temperature (colours, red for warm, blue for cold),and precipitation (rain and snow - black shading), from a scout run of the 20th Century reanalysis. Yellow and red dots mark the locations of the pressure observations available for assimilation - these are from version 4 of the ISPD. The red dots are the observations recovered by oldWeather.org for this period: from the ships Jeannette, Rodgers, and Corwin. Grey fog masks the areas where the reanalysis has little skill (because there are too few nearby observations) - so the weather of the period is still unknown. Rendered at NERSC (nersc.gov)

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    • Arctic weather in 1880-81

      06:05

      from Philip Brohan Added 14 0 0

      Sea-level pressure anomalies (contours, solid for low pressure, dashed for high), and near-surface air temperature anomalies (colours, red for warm, blue for cold) from a scout run of the 20th Century reanalysis. Yellow and red dots mark the locations of the pressure observations available for assimilation - these are from version 4 of the ISPD. The red dots are the observations recovered by oldWeather.org for this period: from the ships Jeannette, Rodgers, and Corwin. Grey fog masks the areas where the reanalysis has little skill (because there are too few nearby observations) - so the weather of the period is still unknown. Rendered at NERSC (http://www.nersc.gov)

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      • Montana - January 1916

        00:14

        from Philip Brohan Added 5 0 0

        Historical weather records, coupled with modern weather-forecasting technology (reanalysis.org) allow us to reconstruct past weather hour-by-hour. This video uses data from the Twentieth Century Reanalysis (esrl.noaa.gov/psd/data/20thC_Rean/ - version 2c) and shows the places where we have observations (yellow dots) sea-level pressure anomalies (contours: solid=low pressure and dashed=high), and temperature anomalies (red=unusually hot, blue=unusually cold). Created at NERSC (nersc.gov).

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        • Weather and the Jeannette

          02:00

          from Philip Brohan Added 107 0 0

          Observations from the arctic voyage of the USS Jeannette (http://en.wikipedia.org/wiki/USS_Jeannette_%281878%29) - rescued by http://oldweather.org . The map shows the route of the ship and the sea-ice for the period as used in the 20th Century reanalysis (20CR: http://esrl.noaa.gov/psd/data/20thC_Rean/). The graph shows sea-level pressure, and near-surface air temperature, as observed by the ship (red dots), as reconstructed by 20CR version 2c (not using the ships observations: light grey band), and as reconstructed by a scout version of 20CR assimilating the Jeannette's pressure observations (dark grey band). Small yellow dots mark the other observations available to the reanalyses. Rendered at NERSC (http://nersc.gov).

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          • Florence Bailey as weather observer

            00:11

            from Philip Brohan Added 46 0 0

            On January 3rd 1887, Florence Bailey (http://en.wikipedia.org/wiki/Florence_Augusta_Merriam_Bailey) noted a temperature of -26 degrees (presumably F) in her diary, which is in the Smithsonian and now being transcribed by volunteers (https://transcription.si.edu/transcribe/7430/SIA-SIA2014-03859). What caused this remarkably low temperature? Our weather records from the time, some also being rescued by volunteers (http://oldweather.org), coupled with modern weather-forecasting technology (http://reanalysis.org) allow us to reconstruct the weather of that time hour-by-hour. The video uses data from the Twentieth Century Reanalysis (http://www.esrl.noaa.gov/psd/data/20thC_Rean/ - version 2c) and shows the places where we have observations (yellow dots) sea-level pressure anomalies (contours: solid=low pressure and dashed=high), and temperature anomalies (red=unusually hot, blue=unusually cold). The high pressure over the central U.S. spreads East - bringing clear skies, northerly winds, and very low temperatures to New York state, where she was on that date. Created at NERSC (http://www.nersc.gov).

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            • Imperial Trans-Antarctic Expedition

              02:06

              from Philip Brohan Added 55 0 0

              The Imperial Trans-Antarctic Expedition (http://en.wikipedia.org/wiki/Imperial_Trans-Antarctic_Expedition), led by Sir Ernest Shackleton, failed to reach its exploration objectives, but did allow groups of scientists to spend many months in the Antarctic, where they made careful observations of the weather. The expedition records have not been published or systematically analysed, but many have been preserved in the archives of the Scott Polar Research Institute (http://www.spri.cam.ac.uk/). Red dots mark the route and observations from the Endurance, as well as sea-ice drift and boat journeys after she sank - including the voyage of the James Caird. Blue dots mark the voyage and drift of the Aurora. Black dots are from the rescue expeditions on the Emma and the Yelcho. Sea-ice estimates and background weather estimates (grey bands) are from the Twentieth Century Reanalysis version 2c (http://www.esrl.noaa.gov/psd/data/20thC_Rean/); small yellow dots mark the pressure observations available to the reanalysis. We are still missing some of the observations: Weddell-Sea party observations for 1916, Aurora temperature observations for part of 1915, and all the observations from the land-base at Cape Evans, are yet to be found. (And it's possible that records from the rescue expeditions on the Southern Sky and the Instituto de Pesca No. 1, and the Ross-Sea party relief expedition on the Aurora, still exist somewhere). Created at NERSC (http://www.nersc.gov).

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              • Shared variance in the 20CRv2c ensemble

                01:20

                from Philip Brohan Added 6 0 0

                Yellow shaded areas mark regions where the ratio of shared variance to individual ensemble menber variance in the 20CRv2c ensemble (ensemble mean variance to ensemble mean variance+spread**2) exceeds a threshold value of 0.36. (Corresponds to a correlation of 0.6 between ensemble members - a reasonable minimum threshold for 'agreement'). Darker yellow marks regions where the ratio exceeds 0.72. Variances are calculated from 6-hourly values for each of four near-surface variables. the calculation is done each month using three months of data centered on that month.

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                • ISPD version 3.2.9

                  07:48

                  from Philip Brohan Added 176 0 0

                  Observations coverage (1851-2008) in version 3.2.9 of the International Surface Pressure Databank (that used in the Twentieth Century Reanalysis version 2c). Each frame shows all the observations for 1 day and there is 1 frame every 5 days (a compromise between keeping as much detail as possible and not letting the video get too long). 24 frames/s. This dataset contains 1,399,120,833 observations over this period. Rendered at NERSC (http://nersc.gov). ISPD: https://reanalyses.org/observations/international-surface-pressure-databank

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                  • Temperature correlation between 20CRv2c and ERA20C

                    01:38

                    from Philip Brohan Added 16 0 0

                    Fraction of shared variance (r**2) in 6-hourly near-surface air temperature (T2m) anomaly between ERA20C and 20CRv2c over 1911-2010. Calculated each month over a seven-month period centred on that month. Although the plot is r**2, it's set to zero in regions where r is less than 0.

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                    • MSLP correlation between 20CRv2c and ERA20C

                      01:38

                      from Philip Brohan Added 8 0 0

                      Fraction of shared variance (r**2) in 6-hourly mean-sea-level pressure anomaly between ERA20C and 20CRv2c over 1911-2010. Calculated each month over a seven-month period centred on that month. Although the plot is r**2, it's set to zero in regions where r is less than 0.

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