patrickbdevaney/mia9 · Datasets at Hugging Face

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MOI Marsh-to-Ocean Index
MSL Mean Sea Level
NAVD88 North American Vertical Datum of 1988
NGVD29 National Geodetic Vertical Datum of 1929
NTDE National Tidal Datum Epoch
RES Renewable Energy Source
RCP Representative Concentration Pathway
UNESCO United Nations Educational, Scientific and Cultural Organization
USGS United States Geological Survey
Appendix A. Datum and Water Level Conversions
A tidal datum [35] provides a geodetic link between ocean water level and a land-based
elevation reference such as the North American Vertical Datum of 1988 (NAVD88). The National
Tidal Datum Epoch (NTDE) in the United States is a 19-year period over which tidal datums
specific to each tide gauge are determined. The current NTDE for the United States is 1983–2001,
and sea level rise projections are referenced to the midpoint of this period (1992) consistent with
design procedures determined by the U.S. Army Corps of Engineers and NOAA’s National Climate
Assessment [36]. Common tidal datums include Mean Sea Level (MSL), Mean High-Higher Water
J. Mar. Sci. Eng. 2017, 5, 31 19 of 26
(MHHW) and Mean Low-Lower Water (MLLW), as defined by the National Oceanic and Atmospheric
Administration [35]. As sea level rises, tidal datum elevations also, rise and a new tidal datum is
established every 20–25 years to account for sea level change and vertical adjustment of the local
landmass [37].
Kopp et al. [9] assumed a water level reference of mean sea level starting at year 2000; however,
the mean sea level datum at the Vaca Key tide gauge, which can be referenced to NAVD88, is with
respect to the National Tidal Datum Epoch (NTDE) centered on 1992. To reference the Kopp projection
to NAVD88, we must first account for sea level rise at the tide gauge from 1992–2000. We quantified
this sea level rise at Vaca Key with an empirical mode decomposition resulting in value of 1.4 cm. This
sea level rise offset is added to the Kopp projections to account for the fact that their projections start
in the year 2000, but that the NTDE mean sea level at Vaca Key is referenced to 1992.
Next, we convert the projections with respect to the NTDE mean sea level datum to the NAVD88
geodetic datum of the topographic elevations. Table A1 lists the NTDE and NAVD88 elevations at the
Vaca Key tide gauge [38], where we find that the NAVD88 datum is 25.1 cm above the NTDE MSL
datum. In other words: MSL referenced to NAVD88 is equal to the NAVD88 datum elevation minus
25.1 cm. We therefore subtract 25.1 cm from all projected water levels with respect to mean sea level in
order to reference them to the NAVD88 datum.
Table A1. Elevations on station datum in meters at Vaca Key, FL (NOAA station: 8723970). Tidal datum
epoch: 1983–2001.
Datum Value Description
NAVD88 1.182 North American Vertical Datum of 1988
MHHW 1.072 Mean Higher-High Water
MHW 1.040 Mean High Water
MSL 0.931 Mean Sea Level
MLW 0.822 Mean Low Water
MLLW 0.775 Mean Lower-Low Water
STND 0.000 Station Datum
Finally, we apply the sea level rise projections with respect to NAVD88 to current mean sea level,
which is not at zero elevation NAVD88. As above, we note that the NTDE (1992) mean sea level at
Vaca Key is −25.1 cm NAVD88, while the current sea level in Florida Bay averaged over 2008–2015
is −14.8 cm NAVD88 (Appendix C). The difference of 10.3 cm reflects sea level rise from 1992–2015
and any local influences of dynamic height between Vaca Key and the three stations where mean sea
level was estimated.
Putting this all together, the elevation of −14.8 cm NAVD88 is the starting elevation of the sea
level projections, as shown in Figure 2 and Appendix B. The projections from Kopp et al. [9], which
have been converted to NAVD88, are then added to this base sea level elevation to predict future mean
sea level in Florida Bay.
The cautious reader might consider that there has been a double accounting of sea level rise, 1.4 cm
representing the change from 1992–2000 and 10.3 cm for sea level rise from 1992–2015. However, these
are two independent adjustments. The 1.4-cm adjustment was solely for the purpose of referencing
the Kopp projections to the mean sea level datum (NTDE), which was then referenced to NAVD88,
a datum conversion independent of the projection starting time. The 10.3-cm accounts for the fact that
we choose 2015 as the starting point of the projections. Had we selected year 2000 as the starting point,
then the 1.4 cm datum conversion would still apply, while the adjustment to a starting sea level of 2000
would be less than the 10.3 cm determined for a 2015 start time.
Appendix B. Tabulated Sea Level Rise Projection
Sea level rise in cm NAVD88 from Kopp et al. [9] at Vaca Key. Values between decades
(2010, 2020, etc.) have been interpolated with a cubic spline. Low is the 50th percentile of the RCP 8.5
J. Mar. Sci. Eng. 2017, 5, 31 20 of 26
projection; high the 99th percentile. An offset of 1.4 cm has been added to account for sea level rise
from 1992–2000 to convert the Kopp projections starting in 2000 to the NTDE MSL datum of 1992.
The NAVD88 datum is 25.3 cm above the NTDE MSL, so that 25.3 cm has been subtracted to convert
NTDE MSL to NAVD88. The projections have been offset to match observed mean sea level over the
period 2008–2015 in Florida Bay of −14.8 cm NAVD88 (Appendix C).
Table A2. Sea level rise in cm NAVD88 from Kopp et al. [9].
Year Low High Year Low High Year Low High Year Low High
2015 −14.8 −14.8 2045 6.8 18 2075 35.8 76.6 2105 68.3 159.9
2016 −14.2 −13.8 2046 7.7 19.6 2076 36.9 79 2106 69.5 162.7
2017 −13.6 −12.8 2047 8.6 21.1 2077 38 81.5 2107 70.8 165.4
2018 −12.9 −11.8 2048 9.6 22.8 2078 39.2 84 2108 72 168.3
2019 −12.3 −10.8 2049 10.5 24.4 2079 40.3 86.5 2109 73.2 171.2
2020 −11.6 −9.8 2050 11.4 26.2 2080 41.4 89.2 2110 74.4 174.2
2021 −10.9 −8.9 2051 12.3 27.9 2081 42.6 91.8 2111 75.6 177.2
2022 −10.2 −7.9 2052 13.2 29.7 2082 43.7 94.5 2112 76.7 180.3
2023 −9.5 −6.9 2053 14.1 31.6 2083 44.8 97.2 2113 77.9 183.5
2024 −8.8 −5.9 2054 15 33.5 2084 45.9 100 2114 79 186.8
2025 −8.1 −4.9 2055 15.9 35.4 2085 47.1 102.8 2115 80.1 190.1
2026 −7.4 −3.9 2056 16.8 37.3 2086 48.2 105.6 2116 81.2 193.4
2027 −6.7 −2.9 2057 17.7 39.3 2087 49.3 108.5 2117 82.2 196.8
2028 −6 −1.9 2058 18.6 41.2 2088 50.3 111.3 2118 83.3 200.2
2029 −5.3 −0.9 2059 19.5 43.2 2089 51.4 114.2 2119 84.4 203.7
2030 −4.6 0.2 2060 20.4 45.2 2090 52.4 117.2 2120 85.4 207.2
2031 −3.9 1.2 2061 21.4 47.1 2091 53.4 120.1
2032 −3.2 2.2 2062 22.3 49 2092 54.4 123
2033 −2.6 3.2 2063 23.3 51 2093 55.4 125.9
2034 −1.9 4.3 2064 24.3 52.9 2094 56.3 128.9
2035 −1.2 5.3 2065 25.3 54.9 2095 57.3 131.8
2036 −0.5 6.4 2066 26.3 56.9 2096 58.3 134.7
2037 0.2 7.6 2067 27.3 58.9 2097 59.3 137.6
2038 0.9 8.7 2068 28.3 60.9 2098 60.3 140.5
2039 1.6 9.9 2069 29.4 63 2099 61.3 143.3
2040 2.4 11.2 2070 30.4 65.2 2100 62.4 146.2

MOI Marsh-to-Ocean Index

MSL Mean Sea Level

NAVD88 North American Vertical Datum of 1988

NGVD29 National Geodetic Vertical Datum of 1929

NTDE National Tidal Datum Epoch

RES Renewable Energy Source

RCP Representative Concentration Pathway

UNESCO United Nations Educational, Scientific and Cultural Organization

USGS United States Geological Survey

Appendix A. Datum and Water Level Conversions

A tidal datum [35] provides a geodetic link between ocean water level and a land-based

elevation reference such as the North American Vertical Datum of 1988 (NAVD88). The National

Tidal Datum Epoch (NTDE) in the United States is a 19-year period over which tidal datums

specific to each tide gauge are determined. The current NTDE for the United States is 1983–2001,

and sea level rise projections are referenced to the midpoint of this period (1992) consistent with

design procedures determined by the U.S. Army Corps of Engineers and NOAA’s National Climate

Assessment [36]. Common tidal datums include Mean Sea Level (MSL), Mean High-Higher Water

J. Mar. Sci. Eng. 2017, 5, 31 19 of 26

(MHHW) and Mean Low-Lower Water (MLLW), as defined by the National Oceanic and Atmospheric

Administration [35]. As sea level rises, tidal datum elevations also, rise and a new tidal datum is

established every 20–25 years to account for sea level change and vertical adjustment of the local

landmass [37].

Kopp et al. [9] assumed a water level reference of mean sea level starting at year 2000; however,

the mean sea level datum at the Vaca Key tide gauge, which can be referenced to NAVD88, is with

respect to the National Tidal Datum Epoch (NTDE) centered on 1992. To reference the Kopp projection

to NAVD88, we must first account for sea level rise at the tide gauge from 1992–2000. We quantified

this sea level rise at Vaca Key with an empirical mode decomposition resulting in value of 1.4 cm. This

sea level rise offset is added to the Kopp projections to account for the fact that their projections start

in the year 2000, but that the NTDE mean sea level at Vaca Key is referenced to 1992.

Next, we convert the projections with respect to the NTDE mean sea level datum to the NAVD88

geodetic datum of the topographic elevations. Table A1 lists the NTDE and NAVD88 elevations at the

Vaca Key tide gauge [38], where we find that the NAVD88 datum is 25.1 cm above the NTDE MSL

datum. In other words: MSL referenced to NAVD88 is equal to the NAVD88 datum elevation minus

25.1 cm. We therefore subtract 25.1 cm from all projected water levels with respect to mean sea level in

order to reference them to the NAVD88 datum.

Table A1. Elevations on station datum in meters at Vaca Key, FL (NOAA station: 8723970). Tidal datum

epoch: 1983–2001.

Datum Value Description

NAVD88 1.182 North American Vertical Datum of 1988

MHHW 1.072 Mean Higher-High Water

MHW 1.040 Mean High Water

MSL 0.931 Mean Sea Level

MLW 0.822 Mean Low Water

MLLW 0.775 Mean Lower-Low Water

STND 0.000 Station Datum

Finally, we apply the sea level rise projections with respect to NAVD88 to current mean sea level,

which is not at zero elevation NAVD88. As above, we note that the NTDE (1992) mean sea level at

Vaca Key is −25.1 cm NAVD88, while the current sea level in Florida Bay averaged over 2008–2015

is −14.8 cm NAVD88 (Appendix C). The difference of 10.3 cm reflects sea level rise from 1992–2015

and any local influences of dynamic height between Vaca Key and the three stations where mean sea

level was estimated.

Putting this all together, the elevation of −14.8 cm NAVD88 is the starting elevation of the sea

level projections, as shown in Figure 2 and Appendix B. The projections from Kopp et al. [9], which

have been converted to NAVD88, are then added to this base sea level elevation to predict future mean

sea level in Florida Bay.

The cautious reader might consider that there has been a double accounting of sea level rise, 1.4 cm

representing the change from 1992–2000 and 10.3 cm for sea level rise from 1992–2015. However, these

are two independent adjustments. The 1.4-cm adjustment was solely for the purpose of referencing

the Kopp projections to the mean sea level datum (NTDE), which was then referenced to NAVD88,

a datum conversion independent of the projection starting time. The 10.3-cm accounts for the fact that

we choose 2015 as the starting point of the projections. Had we selected year 2000 as the starting point,

then the 1.4 cm datum conversion would still apply, while the adjustment to a starting sea level of 2000

would be less than the 10.3 cm determined for a 2015 start time.

Appendix B. Tabulated Sea Level Rise Projection

Sea level rise in cm NAVD88 from Kopp et al. [9] at Vaca Key. Values between decades

(2010, 2020, etc.) have been interpolated with a cubic spline. Low is the 50th percentile of the RCP 8.5

J. Mar. Sci. Eng. 2017, 5, 31 20 of 26

projection; high the 99th percentile. An offset of 1.4 cm has been added to account for sea level rise

from 1992–2000 to convert the Kopp projections starting in 2000 to the NTDE MSL datum of 1992.

The NAVD88 datum is 25.3 cm above the NTDE MSL, so that 25.3 cm has been subtracted to convert

NTDE MSL to NAVD88. The projections have been offset to match observed mean sea level over the

period 2008–2015 in Florida Bay of −14.8 cm NAVD88 (Appendix C).

Table A2. Sea level rise in cm NAVD88 from Kopp et al. [9].

Year Low High Year Low High Year Low High Year Low High

2015 −14.8 −14.8 2045 6.8 18 2075 35.8 76.6 2105 68.3 159.9

2016 −14.2 −13.8 2046 7.7 19.6 2076 36.9 79 2106 69.5 162.7

2017 −13.6 −12.8 2047 8.6 21.1 2077 38 81.5 2107 70.8 165.4

2018 −12.9 −11.8 2048 9.6 22.8 2078 39.2 84 2108 72 168.3

2019 −12.3 −10.8 2049 10.5 24.4 2079 40.3 86.5 2109 73.2 171.2

2020 −11.6 −9.8 2050 11.4 26.2 2080 41.4 89.2 2110 74.4 174.2

2021 −10.9 −8.9 2051 12.3 27.9 2081 42.6 91.8 2111 75.6 177.2

2022 −10.2 −7.9 2052 13.2 29.7 2082 43.7 94.5 2112 76.7 180.3

2023 −9.5 −6.9 2053 14.1 31.6 2083 44.8 97.2 2113 77.9 183.5

2024 −8.8 −5.9 2054 15 33.5 2084 45.9 100 2114 79 186.8

2025 −8.1 −4.9 2055 15.9 35.4 2085 47.1 102.8 2115 80.1 190.1

2026 −7.4 −3.9 2056 16.8 37.3 2086 48.2 105.6 2116 81.2 193.4

2027 −6.7 −2.9 2057 17.7 39.3 2087 49.3 108.5 2117 82.2 196.8

2028 −6 −1.9 2058 18.6 41.2 2088 50.3 111.3 2118 83.3 200.2

2029 −5.3 −0.9 2059 19.5 43.2 2089 51.4 114.2 2119 84.4 203.7

2030 −4.6 0.2 2060 20.4 45.2 2090 52.4 117.2 2120 85.4 207.2

2031 −3.9 1.2 2061 21.4 47.1 2091 53.4 120.1

2032 −3.2 2.2 2062 22.3 49 2092 54.4 123

2033 −2.6 3.2 2063 23.3 51 2093 55.4 125.9

2034 −1.9 4.3 2064 24.3 52.9 2094 56.3 128.9

2035 −1.2 5.3 2065 25.3 54.9 2095 57.3 131.8

2036 −0.5 6.4 2066 26.3 56.9 2096 58.3 134.7

2037 0.2 7.6 2067 27.3 58.9 2097 59.3 137.6

2038 0.9 8.7 2068 28.3 60.9 2098 60.3 140.5

2039 1.6 9.9 2069 29.4 63 2099 61.3 143.3

2040 2.4 11.2 2070 30.4 65.2 2100 62.4 146.2