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MAPPING A HUMAN MAPPING A HUMAN DISCOMFORT INDEX OVER DISCOMFORT INDEX OVER
SOUTH AFRICA SOUTH AFRICA What Does the Future hold What Does the Future hold
Compared with the Present?Compared with the Present?Compared with the Present?Compared with the Present?
Roland Schulze & Nicholas DavisRoland Schulze & Nicholas Davis
Centre for Water Resources Research
University of KwaZulu-Natal
Pietermaritzburg, South Africa
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Human Comfort / DiscomfortHuman Comfort / Discomfort1. The concept of human comfort is based on criteri a of the energy balance between human body and its environment
0 = M ± R ± Cv ± Cd − Ewhere
M is the metabolic heat, R the heat exchange by radiation,Cv the heat exchange by convection, Cv the heat exchange by convection, Cd the heat exchange by conduction and E the heat losses by evaporation.
2. Human body thermal balance consists of maintaini ng the body’s temperature between 36.5 °C and 37°C, with increases or decreases in the body’s temperature producing discomfort
3. If the body’s temperature > 40 °C blood circulation problems appear, and > 41–42 °C coma or total collapse can occur
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HumanHuman Discomfort Indices …1Discomfort Indices …1The three most significant climatic variables for comfort are:
1. Humidity , which controls evaporation and plays an important role at high temperatures where perspiration is the cooling mechanismperspiration is the cooling mechanism
2. Wind , which speeds up evaporation by convection
3. Temperature , as the main heat gain source, as a surrogate of solar radiation
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Human Discomfort Indices …2Human Discomfort Indices …2
In the present work we use Thom’s (1959) Human
Many Human Discomfort Indices have been developed over the years, e.g.Siple and Passel (1945); Brooks (1950); Buettner (1954); The American Society of Heating and Air Conditioning Engineers (1955); Tanenbaum and Sohar (1960); Olgyay (1963) Landsberg (1964); Terjung (1966); Jaureguiand Soto (1967); Watson and Labs (1983), Vinje’s index (1993)
In the present work we use Thom’s (1959) Human Discomfort Index, TDI … a formulation using a combination of air temperature, T (°C) and relative humidity, RH:
TDI (°C) = T − 0.55 ∗∗∗∗ (1 − 0.01 ∗∗∗∗ RH) ∗∗∗∗ (T − 14.5)
Required for this are temporal & spatial databases of daily maximum & minimum temperatures and RH
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Requirement 1 Requirement 1 Databases of Databases of Daily Daily
Maximum / Minimum Maximum / Minimum Temperatures and Relative Temperatures and Relative Temperatures and Relative Temperatures and Relative Humidity Over South Africa Humidity Over South Africa
at Timeat Time --Steps & Local Steps & Local Resolutions that MatterResolutions that Matter
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Development of a Daily Development of a Daily Temperature Temperature Database for SADatabase for SA
1. Methodology1. Methodology
Schulze & Maharaj, 2004
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Examples of Derivatives from the Daily Examples of Derivatives from the Daily Temperature DatabaseTemperature Database
Schulze, 2008
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Verification: July
y = 0.8957x + 0.0206R2 = 0.84
0.0
0.5
1.0
1.5
2.0
2.5
Est
imat
ed
Vap
our
P
ress
ure
(kP
a)
Verification: January
y = 1.0384x - 0.0679R2 = 0.83
0.0
0.5
1.0
1.5
2.0
2.5
0.0 0.5 1.0 1.5 2.0 2.5Observed Vapour Pressure (kPa)
Est
imat
ed V
aapo
ur
Pre
ssur
e (k
Pa)
ea (Pa) = 610.78 x 10(17.269 Ta / (237.3 + Ta)
e (P ) = f (latitude, longitude, distance from
RH (%) = Actual vapour pressure X 100Saturated vapour Pressure
= ed /ea. 100
Determination of Daily Determination of Daily Maximum & Minimum Maximum & Minimum
Relative Humidity over SARelative Humidity over SA
0.0
0.0 0.5 1.0 1.5 2.0 2.5Observed Vapour Pressure (kPa)
ed (Pa) = f (latitude, longitude, distance from sea, altitude, daily temperature range)(Schulze and Chapman, 2008)
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Requirement 2 Requirement 2 Spatial Databases at Spatial Databases at
Local Resolutions that Local Resolutions that Local Resolutions that Local Resolutions that MatterMatter
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Spatial Database to Model Fluxes & Spatial Database to Model Fluxes & Flows at the Local Scales that MatterFlows at the Local Scales that Matter
5 838 Relatively Homogeneous 5 838 Relatively Homogeneous (Interlinked) (Interlinked) QuinariesQuinaries
QnCDBQnCDB: Each with a 50 Year : Each with a 50 Year Record of DAILY Rainfall, Record of DAILY Rainfall,
Schulze & Horan, 2010 Schulze et al., 2010
FLOWPATH CONFIGURATION WHEN MODELLING ATQUINARY CATCHMENT SCALE
QC V11A
V11A 1 V11A 2 V11A 3
QC V11C
V11C 1 V11C 2 V11C 3
QC V11D
V11D 1 V11D 2 V11D 3
Flowpath
Quaternary Catchment Outlet
External Quaternary Catchment
Internal Quaternary Catchment
Procedure: Jenks’ Optimisation using Procedure: Jenks’ Optimisation using Natural Breaks in AltitudeNatural Breaks in Altitude
Record of DAILY Rainfall, Record of DAILY Rainfall, TTmaxmax, , TTminmin , , RHRHmaxmax, , RHRHminmin , , RRss, , EEpp--mm; Plus Soils and Land ; Plus Soils and Land Cover Attributes & DAILY Cover Attributes & DAILY
RunoffRunoff
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Results 1Results 1The Human Discomfort The Human Discomfort
Index Under Present Index Under Present Climatic ConditionsClimatic ConditionsClimatic ConditionsClimatic Conditions
The MidThe Mid --Day (Day (TTmaxmax , , RHRHminmin ) Mid) Mid--Summer Summer (January) Discomfort Situation (January) Discomfort Situation
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Classes of Comfort / Discomfort by Classes of Comfort / Discomfort by ThomsThoms’ Human ’ Human Discomfort Index: January MidDiscomfort Index: January Mid --day day Discomfort Index: January MidDiscomfort Index: January Mid --day day
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Results 2 Results 2 The Human Discomfort The Human Discomfort Index Under Projected Index Under Projected
Future Climatic Future Climatic Future Climatic Future Climatic ConditionsConditions
The MidThe Mid --Day (Day (TTmaxmax , , RHRHminmin ) Mid) Mid--Summer Summer (January) Discomfort Situation (January) Discomfort Situation
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Downscaling: GCM Downscaling: GCM -- LocalLocal
Forcing: Emission Scenarios Forcing: Emission Scenarios
Initial ConditionsInitial Conditions
Global Climate Global Climate
Models (GCMs)Models (GCMs)
(e.g. HadCM3, (e.g. HadCM3,
ECHAM5, ~200 km)ECHAM5, ~200 km) Regional Climate Regional Climate Models (RCMs) or Models (RCMs) or
statistical downscalingstatistical downscaling
(~25 km)(~25 km)
Impact Impact
ModelsModels
(~5 km)(~5 km)
Hewitson, 2010Hewitson, 2010
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GCMsGCMsCGCM3/T47(no DF) (CA)CNRM - CM3 (FR)ECHMA5/MPI - OM (DE)GISS - ER (US)
QUICKFLOW
INTERCEPTION
PRECIPITATION
TOPSOIL
SURFACE LAYER
Downscaling by CSAG to Downscaling by CSAG to > 2 600 rainfall stations> 2 600 rainfall stations
Downscaling to > 400Downscaling to > 400temperature stationstemperature stations
•• Final selectionFinal selection•• Assignment to Assignment to QnCQnC•• Precipitation adjustmentPrecipitation adjustment•• 5 838 x 3 x 5 files of daily P5 838 x 3 x 5 files of daily P
•• Final selectionFinal selection•• Assignment to QnCAssignment to QnC•• Lapse rate adjustmentLapse rate adjustment•• 5 838 x 3 x 5 files of daily5 838 x 3 x 5 files of daily
TTmxdmxd , T, Tmndmnd , R, RSS, E, EPP--MM
METHODOLOGYMETHODOLOGY
GISS - ER (US)IPSL - CM4 (FR)
Present 1971 - 90Intermediate 2046 - 65Distant Future 2081 - 00
RUNOFF
GROUNDWATER STORE
INTERMEDIATE STORE
SUBSOIL
TOPSOIL
QC V11A
V11A 1 V11A 2 V11A 3
QC V11C
V11C 1 V11C 2 V11C 3
QC V11D
V11D 1 V11D 2 V11D 3
. . .
Assigning Homogeneous Assigning Homogeneous Response ZonesResponse Zones
5 838 Interlinked 5 838 Interlinked QuinariesQuinaries
SoilsSoilsLand CoverLand Cover
Climate FilesClimate Files
Lumsden et al., 2010 Schulze et al., 2011
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GCMsGCMsCGCM3/T47(no DF) (CA)CNRM - CM3 (FR)ECHMA5/MPI - OM (DE)GISS - ER (US)IPSL - CM4 (FR)
CHANGE CHANGE ANALYSESANALYSES
Temperature Temperature Related Related AnalysesAnalyses
Rainfall Rainfall Related Related AnalysesAnalyses
Hydrological / Hydrological / HydroHydro--EcolEcol AnalysesAnalyses AgriculturalAgricultural
AnalysesAnalyses
Annual Temperature StatisticsMonthly Temperature StatisticsFrost DaysCold SpellsHeat WavesClimate ZonesValidation Studies Human Discomfort Index
Annual Rainfall StatisticsMonthly Rainfall StatisticsSeasonality and ConcentrationThreshold Rainfalls ExceededShifts in Timing of Rains > ThresholdsShort and Long Duration Design PMeteorological Droughts (S, M, M, / A, M)Validation Studies
IPSL - CM4 (FR)
Present 1971 - 90Intermediate 2046 - 65Distant Future 2081 - 00
AnalysesAnalysesAnnual Runoff/Streamflow StatsCardinal Month StatsThresholds of Streamflows Exceeded Potential EvaporationSoil MoisturePeak Discharge; Sediment YieldHydrological Droughts (Sev, Mod, Mld, / An, Mo)Shifts in Timing of Streamflows > Thresholds1 - 7 Day Design Stormflows (2, 5, 10, 20, 50, 100 yr RP)Env Flows: Indicators of Hydrological AlterationEnvironmental Flows: Water TemperatureEstuarine ResponsesLand Use / CC Dynamics: Mgeni CatchmentCase Studies: Durban; Cape Town; Waterberg,
Blyde, Olifants-Doorn, Berg Socio -Economic Studies: Berg, Mgeni
2nd Order Analyses- Heat Units - Chill Units
3rd Order Analyses- Pests /Diseases (Ch/CM/El/Ea/SbR/OF)- Crops (Mz, Wh, So, Sb Sc)- Pastures (Ec, Kik)- Crops - Horticulture- Production Forestry (Am, Eg, Pp)- Primary Production- Irrigation Requirements
Vegetation Dynamics re Climate Ch Case Studies: Blyde, Olifants-Doorn
Schulze, 2011; 2012
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How do How do Outputs Outputs
from from Different Different
GCMs GCMs Compare Compare
in the in the Control Control Period? Period?
19711971--19901990
Category: Too hot Category: Too hot and humid, and humid,
midmid --day Januaryday January
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Projected Projected IncreasesIncreases into into the Future in Days in the Future in Days in
January which are January which are too Hot / Humid for too Hot / Humid for
Human ComfortHuman Comfort1971 - 1990
2046 - 2065
2081 - 2100
GCM: ECHAM5/MPI-OM
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How do How do Projected Projected Outputs Outputs
from from Different Different
GCMs GCMs Compare Compare into the into the into the into the Future? Future?
2046 2046 -- 20652065
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Projected Projected DecreasesDecreases into into the Future in Days in the Future in Days in
January which are January which are Partially ComfortablePartially Comfortable
1971 - 1990
GCM: ECHAM5/MPI-OM
2046 - 2065
2081 - 2100
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Concluding ThoughtsConcluding Thoughts1. GCMs give consistent results on increases in
mid -summer human discomfort 2. Many sectors could be affected by this, e.g.
Tourism industry Building design City planning Construction industry Construction industry Agricultural workers Medical aid Sporting codes
3. Further work could be extended to Cold discomfort indices Livestock heat stress indices ….
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